text: Category:Subject:Microeconomics

title: Category:Subject:Microeconomics


text: Shelf:Microeconomics/ancestry

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Shelf:Microeconomics/ancestry


text: Category:Shelf:Microeconomics

title: Category:Shelf:Microeconomics


text: Category:Shelf:Microeconomics/all books

title: Category:Shelf:Microeconomics/all books


text: Classical Nahuatl/Printable version

title: Classical Nahuatl/Printable version


text:
Oberon/ETH Oberon/Tutorial/Mouse

Using the mouse and the keyboard

[ Text | Contents | Index | Master index ]

This is a usage tutorial. Hardware, configuration and functionality are addressed in the mouse page and keyboard page.

Tutorial objective
Theory on the mouse operation with practical drill using a three-key, a two-button mouse or even a single button mouse as is used by Macintosh systems. The terms "key" and "button" are used interchangeably in the literature or in advertisements. We have chosen to use the term "key" for the mouse device, because "button" designates an element (called a gadget) of the graphical user interface in the Gadgets System. Estimated time: 40 minutes.

Using the mouse and the keyboard
Oberon is controlled by a 3-key mouse. Physical movement of the mouse on a flat surface translates into movement of a mouse cursor on the plane of the display. This cursor has the shape of an arrow, the tip of which is named mouse focus. The focus designates the object on which the mouse actions described below will operate. There are three mouse actions of importance: clicking, dragging and interclicking. Clicking: pressing a key and releasing it, without moving the mouse. Exercise this: only a tiny portion of the tutorial is visible right now. To continue reading what follows, move the mouse focus into the scroll bar (at the left) at the height of this line and click the left mouse key. If you have a Macintosh single button mouse, click that button. The text will scroll forward, but you will learn more about scrolling very soon. Dragging: pressing a key and holding it down while moving the mouse. Interclicking: simply pressing a key or dragging on a key, and pressing one of the other two keys, until finally all keys are released (in any order). The first key pressed determines the action, and the second key pressed modifies it.

Mouse varieties
Oberon is fine-tuned toward a 3-key mouse and a large number of functions can be activated by single mouse key clicks and interclick combinations. Not only have most Macintoshes a single button mouse, but many IBM compatible PCs have a two-button mouse, so that the missing mouse keys have to be emulated by keyboard keys. If you are using such a PC, with Windows use the left Ctrl key as a substitute for the missing middle mouse key, but with Native Oberon use the left Alt key. If you are using a Macintosh, use the left control key as middle mouse key and the alt key as right mouse key.

Scrolling
In most cases, the extent of a document such as this tutorial (in its two-dimensional space) is bigger than the viewer frame (Note: Oberon uses "viewer" where other systems use "window"). Thus, you will want to move the document relative to the viewer to gain access to invisible portions. This process is called scrolling and is performed with the mouse when the mouse focus is positioned in the scroll bar located at the left of the viewer.

The scroll bar features a position mark which is adjusted at each scroll operation. The relative position of this mark in the scroll bar is the same as the relative position of the first visible line in the entire text.

To exercise scrolling, position the cursor in the scroll bar and verify by yourself that (watch the position mark adjusting itself):
 * Dragging on the left key tracks lines: lines are underlined as the cursor moves up or down. On release, the last line tracked will appear at the top. Clicking the left key moves the respective line to the top. Known as scroll forward.
 * Dragging on the right key tracks lines: lines are underlined as the cursor moves up or down. On release, the last line tracked will appear at the bottom. Clicking the right key moves the respective line to the bottom. Known as scroll backward. This adjustment is termed tracking lines.

The following interclick actions are also defined:
 * Pressing the middle key and interclicking the left key scrolls to the end of the document. Known as scroll to bottom.
 * Pressing the middle key and interclicking the right key scrolls to the beginning of the document. Known as scroll to top.

Finally, clicking the middle mouse key scrolls the document so that the top line in the viewer has the same relative position in the document as the mouse focus in the scroll bar. Consequently, the position mark moves to the mouse focus. Also known as absolute positioning.

Select - Mouse Right key - MR
Text and objects are selected through clicking or dragging on the right mouse key. On the display, selected objects are visually characterized, typically in reverse video. Moving the mouse focus and clicking the right key again clears the existing selection and starts a new one. The selection may be removed altogether by hitting the Esc key on the keyboard, or the F2 key with Native Oberon.

Select each of the following letters or calendar object in succession: A B C.

A larger piece of text is selected by first moving the mouse cursor to the start of the desired selection and then dragging on the right mouse key. On the display, the selected area is shown in reverse video and adjusted continuously as the mouse is moved. This adjustment is termed tracking the selection. The selection process is completed when the mouse key is released. Notice that carriage return characters contained in a selection are revealed by the reverse video.

Select the following text from here ->Selected text stretch which goes on and on and on and on and on and on<- to here.

Now learn to improve the selection process: select several lines of text by first moving the mouse vertically and then horizontally left or right as need be. Clear the selection.

Selecting a line: The text stretch from the mouse cursor to the left edge of the viewer is selected if the right mouse key is clicked two times without moving the mouse. It is not necessary for the two clicks to be in quick succession. Select this line entirely including the full stop.

Note: Double clicking or clicking a key twice in rapid succession as is known from other systems is not used in Oberon.

Point - Mouse Left key - ML
Below you see a small viewer which might receive typed characters at explicitely designated points. This leads to the concept of the insertion point which is made visible with the caret symbol. The tip at the top is the caret focus which determines the insertion point: when a character is typed on the keyboard, it is inserted at the right of the caret, and the caret moves one place to the right. The character at the left of the caret is removed by hitting the Backspace key (<-). The caret then moves one place to the left. Also a copied text selection (you will soon learn how this is done) appears to the right of the caret. The viewer with the caret is called the focus viewer. The focus viewer is unique.

Move the mouse cursor inside the viewer below and set the caret in place by clicking the left mouse key. Moving the mouse focus and clicking the left key again moves the caret to a new point.

While dragging on the left key, the caret is tracked, that means it jumps from character to character or from object to object, trying to follow the cursor. This adjustment is termed tracking the caret. Try even to drag the cursor below and around the viewer. You clearly see that the focus viewer does not change.

The focus viewer will only change after you click the left mouse key outside of that small viewer. Interestingly enough, if you click here in this viewer, the caret's shape changes.

In desktops and panels the insertion point of a gadget is made visible by another caret symbol. Place an insertion point of that shape approximately here -> <-. You will have noticed that the caret focus at the center of the cross can be adjusted pixel-wise.

A third caret symbol is used in text fields like this one. Set the caret with a left mouse key click. This sets the focus point inside the text field. Text may be inserted and edited according to the rules described in Editing with the mouse, though it is limited to a single line (ending with a carrier return). Have you noticed that the focus viewer is unique?

Execute - Mouse Middle key - MM
Definition: an Oberon command is denoted by a character string having the following structure: Module.Procedure (or briefly M.P) where Procedure is the name of a procedure exported by a module named Module written in Oberon.

In Oberon a text is taken literally: a sequence of characters. If this sequence is to be interpreted as a command, it is not necessary for the characters to be in a special place, that is in a command line. In a text viewer like this one, a command and its parameters may appear anywhere and may be executed by pointing at the command name with the mouse cursor and clicking the middle mouse key. While the middle mouse remains pressed, the word pointed at with the mouse cursor is underlined. On release of the key, Oberon tries to execute the command. In an ETH Oberon system, MM on System.Time and watch the additional line appear in the Oberon.Log.

The last line in the log now displays: System.Time dd.mm.yy hh:mm:ss

You will like to use a simple and lean expression such as 'click on ....' (a command or a word) instead of this emphatic but equivalent 'when the mouse focus is positioned on this command, click the middle mouse key and the command will be executed'.

When dragging on the middle key, words are tracked; that is, each new word pointed at is underlined. This adjustment is termed tracking words. The same holds true when graphical objects flow within the text stream.

Try it with this color picker which will enlarge and shrink again.

Cancelling a mouse action
When a wrong key is pressed, pressing all keys cancels any action that would otherwise be initiated. The same holds true for an interclick.

Editing with the mouse and the keyboard
We have learned the primary functions of the left (point) and the right (select) mouse keys in a text editor. Further editing actions may be controlled by interclicks.

The following standard actions are provided:

While tracking the selection (dragging on the right key):

 * interclicking the left key deletes the selection (equivalent to cut in other editors) or
 * interclicking the middle key copies the selection to the caret location on release of the right key.

While tracking the caret (dragging on the left key):

 * interclicking the middle key copies the most recent selection to the caret or
 * interclicking the right key copies the attributes of the character to the right of the caret to the most recent selection.

Verify all these assertions by yourself using the text editor appearing below as playground. Set the caret in place and copy a few characters including these -> A B C D with different font and color attributes. Insert also text via the keyboard. Now go!

You should observe the caret's movement (one place to the right) for each character typed on the keyboard and more important still, after having copied a text portion to the caret. Chaining further text portions intermixed with keyboard input is made easy. Likewise the caret is ideally positioned after you have deleted a text portion.

Editing, i.e. inserting, deleting or copying text at the caret, has a side-effect: the selection is removed.

When typing text, the text scrolls up to show what is being typed. If the end of a text is visible and text is inserted at the end, the text scrolls to show the new end of the text.

Now copy (or type) a few words in the next two tiny text viewers and observe the following:

 * 1) Text may be selected in both: the selection is not unique.
 * 2) Of all the selections only one is the most recent selection.
 * 3) If a viewer contains a selection, typing an additional character or copying a selection to that viewer clears the selection.

Thus remember this: to copy the same text stretch at different places in a viewer, place the text to copy in a separate viewer, select it and insert it repeatedly at the caret with a left + middle interclick.

Note: The two variants of the "copy selection" correspond to the well-known copy-and-paste used in other text editors. Oberon does not have a cut-and-paste operation.

Once the caret is set, the four arrow keys (left, right, up, down) are used to move the caret to the previous or to the next character or line. The Page Up and Page Down keys are used to scroll one page up or down respectively. By default, pressing the ENTER key does auto-indentation. Pressing ENTER, starts a new paragraph. The same number TAB or space characters found at the beginning of the previous paragraph is inserted at the beginning of the new paragraph.

Marker * and marked viewer - F1
Some Oberon commands take a star character "*" as (usually first) parameter. Prior to the execution of such a command, the user must mark the viewer or the object that should be used by the command as one of its parameters. Marking is done by moving the mouse cursor inside the viewer or the object and by hitting the F1 key on the keyboard. That point is made visible by a star-shaped marker (Warning: this marker is a fake, it belongs to this text).

The viewer containing the marker focus (the center of the pattern) in its frame boundary is said to be marked.

The marker is unique: if it is set, an attempt to place another one will erase the old one.

To convince yourself try this: set the caret in a free area of a desktop (that is how the work surface on your display is called in Oberon) with a left mouse key click, mark this viewer (F1) and click on this command -> Icons.InsertIcon *

An icon captioned "Mouse.html" appears at the insertion point. You should by now know how to delete the icon: set the mouse focus on the icon and interclick right + left mouse keys.

Removing all marks - Esc
Hitting the Esc key on the keyboard, or the F2 key with Native Oberon, removes all the selections, the caret (do you remember the 3 shapes?) and the (star-shaped) marker

Note that hitting the Esc key makes the marker invisible only: the viewer, which displayed the marker just before, remains the marked viewer. To verify this assertion, set the caret in a free area of the desktop as you did earlier, and click on -> Icons.InsertIcon *. Delete the icon which just appeared.

Caution: The marker is fixed to the screen, not to the viewer. Therefore, it is good practice to set the marker explicitly if it has a significance in a subsequent action.

Using the keyboard
In Oberon, the principal role of the keyboard is to enter text. The caret must be visible in one of the viewers.The following table shows the character set that is used by the Oberon System. Between 20X and 7FX (second, third and fourth rows) lie the standard ASCII characters. They are produced with the respective labelled keys, including the use of SHIFT. The collection of accented characters, appearing in some country alphabets, are also defined. They appear in the fifth row.

Some combinations of keyboard input can be used to create the accented characters: press and release the accent key first, then press the appropriate letter. Accent keys, which also are known as nonescaping keys or dead keys, are intended to be used only in conjunction with other keys. To create the accent character by itself, press the accent key, then the Spacebar.

You can always use this ASCII character table to insert accented characters and any other represented character into a document directly without the help of the keyboard. Refer to ASCIITab.

PC with Oberon System 3 for Windows
The Ctrl key is used to produce the German umlaut characters:

With a German keyboard, if the appropriate keyboard driver is installed, ä, ö, ü, Ä, Ö, Ü and ß can also be typed directly.

Additionally to character keys there is a small number of command keys, as follows:

 * F1: mark a viewer as the destination of a command.
 * Esc: remove all marks (neutralize).

In a Windows environment, Oberon commands cannot be interrupted with Ctrl-Break. This is due to the cooperative multitasking strategy of Windows 3.1. The only way to stop Oberon is by using Ctrl-Alt-Del. Windows might be clever enough to kill only the Oberon program; sometimes it is not.

MacOberon

 * F1 or Enter on the keypad: Mark viewer.
 * esc: Remove all marks (neutralize).
 * num-lock: insert a text style at the caret in a text.

What's next?
Choose a tutorial among those included in this distribution. You should know that there is a lot more to say about using the mouse in the usage page of Prof. Wirth and in Introduction to Gadgets.

Index
[ A | C | D | E | F | I | L | M | P | R | S | T ]

A

absolute positioning

C

cancel caret focus caret caret caret clicking copy attributes copy selection over to caret copy selection to caret copy-and-paste

D

delete selection dragging

E

editing Esc key Esc key execute

F

F1 key F2 key F2 key focus viewer

I

insertion point interclicking

L

left mouse key

M

marked viewer marker focus marker middle mouse key most recent selection mouse actions mouse cursor mouse focus

P

point position mark

R

relative positioning right mouse key

S

scroll backward scroll bar scroll forward scroll to bottom scroll to top scrolling selection

T

tracking lines tracking the caret tracking the selection tracking words

Revised on 23 Nov, 1996 Installed on 30 05 1997

title: Oberon/ETH Oberon/Tutorial/Mouse


text: ANTFARM/Printable version

title: ANTFARM/Printable version


text: Paper Mario: The Thousand-Year Door/Printable version


text: Making an Island/Printable version

title: Making an Island/Printable version


text:
Using an Abacus/Modern division

Euclidean division
If we consider two natural numbers $$a$$ and $$b$$, the division of $$a$$ by $$b$$ (indicated as $$a/b$$ or $$a \div b$$) answers the question of how many times the number $$b$$ is contained in number $$a$$. Number $$a$$ in $$a/b$$ is called the dividend and $$b$$ the divisor. The answer is called the quotient.

Let's take $$a=1225$$ and $$b=35$$ as an example. There is no simpler way to proceed to answer the question than by repeated subtraction counting the number of times we subtract the divisor from the dividend. We can do it directly on the abacus using a column as counter:

Thus we discover that the number $$35$$ is contained exactly $$35$$ times in $$1225$$, since we cannot continue to subtract $$35$$ without starting to deal with negative numbers. Therefore, in this example, the quotient is: $$ q = 35 $$.

As we can see, in this case we can write $$1225 = 35 \times 35$$ or

$$a = q \times b$$

which we cannot expect in the general case. If we repeat the process with $$a = 1240$$, we would see that after subtracting $$35$$ times $$35$$ we would have $$15$$ left on the abacus, from which we cannot continue subtracting $$35$$ without entering negative numbers. Therefore we have that $$1240 = 35 \times 35 + 15$$; that is, the result of dividing $$1240$$ by $$35$$ is a quotient of $$35$$ leaving a remainder of $$15$$. In general we will have:

$$a = q \times b + r$$

where:
 * $$a$$: dividend
 * $$b$$: divisor
 * $$q$$: quotient
 * $$r$$: remainder

In the case that the remainder is zero, the dividend is a multiple of the divisor.

This is the concept of Euclidian division for natural numbers to which the division of numbers with decimal fractions can be reduced.

Some improvements: Chunking methods
The procedure followed in the previous section is the simplest possible conceptually, but it is extraordinarily long and inefficient. Instead of starting directly by subtracting the divisor $$b$$ ($$35$$) from the dividend, let's start by asking what power of 10 times the divisor we can subtract from the dividend; in our case: can we subtract 3500, 350, or only 35? Clearly we can subtract 350 and we will start subtracting 350 chunks, and when we cannot continue, we will start subtracting 35 chunks as follows:

Which has been a lot faster (We have intentionally reduced the distance between the counter and the dividend as much as possible. This obscures the process somewhat but brings us closer to what we will routinely do with the modern division method. Please study the above calculation carefully using your own abacus). Let's continue from here looking for even more efficiency.

If we can easily double the divisor and retain it in memory, we can shorten the operation by subtracting one or two times the divisor chunks.

Or even better if we can build a table like the one below by doubling the divisor three times :

which is somewhat shorter and, clearly, nothing could be faster than having a complete multiplication table of the divisor

Multiplication table
then

There is no doubt, this is an optimal division method, nothing can be faster and more comfortable ... once we have a chunk table like the one above. But calculating the chunk table is time consuming and requires paper and pencil to write it and this extra work would only be justified if we have a large number of divisions to do with the same common divisor.

In 1617 John Napier, the father of logarithms, presented his invention to alleviate this problem consisting of a series of rods, known as Napier's Bones, with the one-digit multiplication table written on them and that could be combined to get the multiplication table of any number. For example, in our case

There is no doubt that such an invention spread to the East and was used in conjunction with the abacus, but this use must be considered as exceptional; not everyone had Napier bones close at hand. Another tool is needed and that tool is the traditional 1-digit multiplication table that is learned by heart and that we are going to use as an approximation to the specific multiplication table of the divisor (the one used above), this table will guide us to choose the digit of the quotient that we must try.

It should be noted that the above procedures do not exhaust the possibilities of the chunking methods. If you read The Definitive Higher Math Guide on Integer Long Division article, you will be amazed at the variety of division methods that can be performed.

Modern vs. traditional division
The modern method of division is so called because throughout the first half of the 20th century its use has displaced that of the traditional method, but in fact it is much older than this, having been displaced by it in the 13th century. A characteristic of the modern method is the use of the 1-digit multiplication table both as a guide to the choice of the interim quotient figure that we have to try and for the calculation of the chunk that we have to subtract from the dividend.

By comparison, the traditional method uses both a special division table as a guide for the interim quotient figure and the multiplication table for calculating the chunk to subtract.

The main reason why the modern method began to displace the traditional method in Japan after the Meiji Restoration is that it can be learned more easily and quickly by those who already know how to divide with paper and pencil, since it does not require memorization of the complex division table. On the other hand, the traditional method makes the division a completely automated process, without the need to think, one only has to follow the rules to obtain the result, which allows the operation to be carried out without any mental fatigue. If you are interested in this topic you can consult the Wikibook: Traditional Abacus and Bead Arithmetic.

Key point of division with the abacus
One of the key points of learning abacus is to be aware that this instrument allows us to correct some things very quickly and without leaving traces, which makes the abacus an instrument especially suited to trial and error procedures. This is specially useful in the case of division. So, if we have to divide 634263÷79283, instead of busting our brain trying to find the correct quotient figure, we simply choose an approximate provisional or interim figure by simplifying the original problem to 63÷7 and test it by trying to subtract the chunk (interim quotient digit)✕79283 from the dividend; one of the following will occur:

 * The interim quotient digit is correct
 * that is, we can subtract the chunk (interim quotient digit) ✕ (divisor) without entering negative numbers but we cannot subtract the quotient one more time because the remainder is less than the divisor.

 * It is insufficient and we must revise it up
 * we can subtract the chunk (interim quotient digit) ✕ (divisor) without entering negative numbers but we can still subtract the quotient one more time because the remainder is greater/equal than the divisor. We add one to the interim quotient and subtract the divisor again from the remainder.

 * It is excessive and we must revise it down
 * this is the most complex and error-prone situation. We usually discover too late (in the middle of the chunk subtraction) that the interim figure is excessive and we need to go back, subtract one from the quotient, and restore the dividend/remainder by adding what has been subtracted in excess before we can continue.

Therefore, the process of obtaining a digit of the quotient has two phases: Once we have found the correct figure, we will generally have a non-zero remainder that will act as a dividend if we want to extend the division to the next digit of the quotient.
 * 1) Choose an interim quotient digit.
 * 2) Test if it is correct and modify it if not.

We will see all of this throughout the examples that follow, but first, we need a few words about how to organize the division on the abacus.

Modern division arrangement
The dividend is the active term with which we are going to work in the abacus, the divisor is inactive and remains unchanged during the operation, in fact it is not essential to enter it in the abacus but it is recommended, especially for beginners. As in the case of multiplication, there are two styles to place dividend and divisor on the abacus, each with its advantages and disadvantages.

Traditional Chinese arrangement
The divisor goes to the far right of the abacus while the dividend is to the left, leaving at least two columns free to its left.

Traditional Japanese arrangement
The divisor goes to the extreme left of the abacus while the dividend is to its right, leaving at least four free columns between the two terms.

In this book we will use the Japanese style for the examples, but feel free to try both.

Placing the quotient figure
The interim quotient figure is placed in one of the two columns directly to the left of the dividend. To decide which one we need to compare the divisor with an equal number of the first digits of the dividend, adding zeros to its right if necessary; call this the working dividend:
 * Working dividend greater than or equal to the divisor
 * this means that the divisor goes into the working dividend and the quotient, i.e. the number of times the divisor goes into the working dividend, is arranged in the second column to the left of the first digit of the dividend
 * Example: 827÷46, 82, the working dividend, is greater than 46, then the interim quotient goes to the second column to the left of dividend. Multiplication table suggest us using 2 as interim quotient (simplify 827÷46 to 8÷4)

 * {| class="wikitable" style="font-family:Courier; line-height: 1.10em;"

! Abacus !! Comment
 * + 827÷46
 * ABCDEFGHIJKLM
 * 46   827
 * 46 2 827
 * Place interim quotient 2 in E
 * }
 * 46 2 827
 * Place interim quotient 2 in E
 * }
 * Place interim quotient 2 in E
 * }

 * Working dividend smaller than the divisor
 * this means that the divisor does not go into the working dividend. In this case, we need to include the next digit of the dividend, or a zero if there are no more left, in our working dividend, and the quotient, the number of times the divisor goes into this expanded working dividend, is arranged in the column directly to the left of the first digit of the dividend
 * Example: 18÷467, 180 is less than 467, then the working dividend is 1800 and the interim quotient goes to the first column to the left of dividend. Multiplication table suggest us using 4 as interim quotient after simplifying 1800÷467 to 18÷4.

 * {| class="wikitable" style="font-family:Courier; line-height: 1.10em;"

! Abacus !! Comment
 * + Caption text
 * ABCDEFGHIJKLM
 * 467   18
 * 467  418
 * Place interim quotient 4 in G
 * }
 * 467  418
 * Place interim quotient 4 in G
 * }
 * Place interim quotient 4 in G
 * }

Examples
You should start by doing exercises with single-digit divisors and later try divisors with two, three, etc. figures. With one-digit divisors you should never have to revise up or down. For example you can divide 123456789 by the digits 2, 3, ..., 9. Let's see the division by 9 here.

Example: 123456789÷9 = 13717421

 * Please read the "->" symbol as: "the multiplication table suggests using ...".
 * As you will see, in all cases except the last one, the working dividend is less than the divisor and we need to expand it to two digits.

123456789 is a curious number, it is precisely the product of 9 by 13717421, a large prime!

Example: 1225÷35 = 35 Two-digit divisor. Revising down and up
Note: We have subtracted 4 × 3 = 12 from FGH, but if the correct quotient digit is 3, we should have subtracted 3 × 3 = 9, so we subtracted 3 in excess (just the first digit of the divisor). We must return this excess before continuing.

Now, suppose that after our "bad experience" revising down the first figure of the quotient, and in an excess of prudence, we choose 4 as as the second interim quotient instead of 5 as suggested by the multiplication table. Then we continue this way:

Example 1÷327
So far we have considered divisions between natural numbers with quotients and remainders as well as natural numbers, but we can operate with decimal numbers exactly as we do in written calculation with long division. For example, let's find the inverse of 327; that is, 1/327 in an abacus with 13 columns.

We have obtained $$3058$$ as the first digits of $$1/327$$, but $$ 1/327 \approx 1/300 = 1 / (3 \cdot 100) = (1/3) \cdot 0.01 \approx 0.33 \cdot 0.01 = 0.0033 $$ so our result is actually $$0.003058$$. See below the rule to find the unit rod of the division.

Example: 634263÷79283 = 7,999987..., a tricky case
Finally let's get the first digit of the quotient of this especially malicious division

There is no doubt that in this case rounding the divisor 79283 to 80000 would have given us better results since 63÷/8 suggests using 7 (the correct figure) as the interim quotient digit.

The unit rod and decimals
The counterpart of the rule to find the unit rod of multiplication is the following rule for division:

The following table shows the $$ n $$ values for some divisors:

Example: 1/327 (we have seen it above)

Multiplication and division as inverse operations
In written calculations we can always review our calculation to make sure that we have not made mistakes and that the result obtained is correct. In calculations with the abacus this is not possible since the abacus does not keep memory of the past and of intermediate results. We can resort to some sanity tests such as casting nines or elevens out, but the traditional way of checking the results with the abacus has been either to repeat the calculations or to undo the calculations.

Undoing additions and subtractions is as simple as starting from the result and subtracting what we have added, adding what we have subtracted; If we do both the calculation and the verification correctly, we should end up with a reset abacus. To verify a multiplication we will use division and, reciprocally, to verify a division we will use multiplication, adding the remainder if there is one. After doing this we will return the abacus to its starting state with the two original operands in their initial positions. Let's see an example:

It has been suggested in this book to use the number 123456789 for your first exercises in both multiplication and division by a single digit. Try combining them with the reverse operation; for example: divide 123456789 by 9 to get 13717421 and multiply this result by 9 to get 123456789 back to the same starting position on the abacus. Or start by multiplying 123456789 by 9 to get 1111111101 and then divide by 9 to get back to where you started. Try all the digits from 2 to 9.

External resources
Exercise sheets

title: Using an Abacus/Modern division


text: Bus Operation in the United Kingdom/Printable version


text: Android/Printable version

title: Android/Printable version


text:
Old English/Authentic Old English Phrasing

This page should contain and comment only on attested historical Old English phrasing, ideally derived from Old English natural prose, but poetry examples may also be included. Glossings of Latin phrases may also be included if necessary, so long as there is no reason to suspect that the Old English translation given might be unnatural. Glossings are especially acceptable as supporting evidence to phrases that are also attesting in natural prose. Specific quotes of historical Old English passages should be used, with their text and document information included. Interpretative commentary, including cultural commentary, may also be given.

Aren't you just doing well for yourself!
"Hū færst þū lā!" - "How you are getting along indeed!" (literal)/"Aren't you just doing well for yourself!" (more idiomatic)

Hello
The best-attested positive colloquial greeting on encountering someone in OE, is:

"Ƿes hāl" - "Be well"

There are a number of other attestations of the same or very similar phrases.

Note that in Late West Saxon, imperative forms of "bēon" came to be preferred over "ƿesan".

"Bēo gesund" - "Be well" (to one person; it is given as a translation of Latin ave and salve)

From this we can easily deduce in West Saxon Old English:

"Bēoð hāle/ġesunde." - "Be well/hello" (to more than one person)

And in Anglian Old English and perhaps also in earlier West Saxon Old English:

"Ƿesað hāle." - "Be well/hello" (to more than one person)

Note that in Beowulf line 2418, we find:

"Gesæt ða on næsse niðheard cyning, þenden hælo abead heorðgeneatum, goldƿine Geata."

English: "The adversity-hardened king, treasure-friend of the Geats, then sat on the headland, while be bade health to his hearth-companions."

This is suggestive that this greeting, and other similar greetings, was a normal greeting in Old English (as well, it is glossed, as explained above, for a common Latin greeting - evidently, Ælfric thought it was the right translation for such a normal greeting). Although, exactly what weight it had, is not fully clear. It may not necessarily have been said just as frequently as "hello" in Modern English. It may have embodied literal well-wishes for someone's health, and felt more "meaningful" than the Modern English "hello". It is notably absent from Ælfric's Colloquoy on Occupations, which might suggest that it was only reserved for meaningful greetings of well-being; or might it reflect that it is not a thoroughly authentic portrayal of Old English social norms.

Method 1
"Hū mæġ hē?" - "How is he?"

The answer, in the same text on the same page, is:

"Hi cƿædon þæt he ƿel mihte" - "They said that he was well."

Taking these as a precedent, you could also say:

"Hū meaht þū?" - "How are you?" to one person.

"Hū magon ġit"?" - "How are you?" to two people.

"Hū magon ġē?" - "How are you?" to 3 or more people.

"Iċ mæġ ƿel." - "I am well."

"Hē mæġ ƿel." - "He is well."

"Ƿē magon yfle." - "We are poorly."

And so forth.

Note that "magan" can mean "have strength". So, there may be an implication that it is asking about someone's physical health, or overall health, rather than more trivial niceties.

There is no evidence that this was used a trivial conversational question in Old English as in Modern English, but it is an authentic phrase, and it has the correct meaning.

Method 2
"Hū eart þū nū?" - "How are you now?"

Which is answered in the same text by:

"He him andsƿarode & cƿæð: oð ðis ic ƿæs sƿiðe yfle, ac nu ic eom sƿiðe ƿel, forþon þe todæg ic onfeng þam gemanan, þe ic ær fram asceaden ƿæs." - "He answered him and said: until now I was very poorly, but now I am very well, because today I joined the fellowship which I was previously excluded from."

The nature of the answer shows clearly that this question applied to fluctuating conditions which could change from day to day, and applied to emotional state as well as physical health.

Note that the word of condition (ƿel, yfle) is an adverb, not an adjective.

From this we can derive the following phrasings:

"Hū eart þū?" - "How are you?" (to one person)

"Hū ƿǣron ġit?" - "How were you two?"

"Ƿē ƿǣron yfle." - "We were poorly."

"Iċ eom ƿel." - "I am well."

And so forth.

There is no evidence this was used as a trivial conversational question in Old English, but it has the correct meaning, and it is an authentic phrase.

Method 1
"Hū eald eart þū?" - "How old are you?"

"Ic eom tyn geara eald." - "I am ten years old."

Method 2
"Hū fela ƿintra hafast/āhst þū (on yldo)?" - "How many winters do you have (in age)?"

"Ic āh/hæbbe sixtȳn ƿintra (on yldo)." - "I have sixteen winters (in age)."

Note that this method likely specifies exact number of winters a person has lived through. Winters were a notable method of measuring age, because winter was a harsh time of year - children, sick, and elderly would be more likely to die during the hardship of winter.

It could easily be adapted to the more popular modern metric of "years", simply by replacing "ƿintra" - "winters/of winters (quantitative)", with "ġēara" - "years/of years (quantitative)".

Method 1
"Mē/Mec hyngreð" - "I'm hungry" (literally, "I'm hungering" or "It's making me hungry.")

Note that "mec" would be used in early Anglian dialects; but "mē" would be used in West Saxon (and possibly later Anglian dialects).

Method 2
"Iċ hyngriġe" - "I'm hungry" (literally, "I'm hungering").

Method 3
"Iċ eom hungriġ/hungrigu" - "I'm hungry"

Note that "hungriġ" would be said by a man, "hungrigu" by a woman.

What's the matter?/What is it?
"Hƿæt is þē, mīn hlāford?" - "What's the matter, my lord?"

Note that all usage examples suggest a context of consternation, more or less similar to "What's the matter?" However, the literal meaning of the phrase, "What do you have?", is very neutral, and so is suggestive that the question could probably be used to inquire about any particular circumstance or object of attention that is relevant to someone. For example, if someone seemed unusually happy, it would likely also be fine to say "Hƿæt is þē?" - "What's up with you?" However, the context of consternation would be one prominent use case.

This seems to be a literal translation of Latin "Quid tibi est?", and as such, it may well not reflect colloquial Old English. However, it is grammatically correct; and there are various other Old English phrasings which are similar and related in meaning. In the worst case, it was not colloquial, but nevertheless most likely did not sound too strange to Old English ears.

We can easily derive:

"Hƿæt is inc?" - "What's the matter?/What's up with you?" (to 2 people)

"Hƿæt is ēoƿ?" - "What's the matter?/What's up with you?" (to 3 or more people)

Method 1
"Hƿæt hāttest þū?" - "What are you called?"

"Iċ hātte Iōhannes." - "I am called John."

Note that the verb in "þū hāttest" - "you are called" and "iċ hātte" - "I am called" and "hēo/hē hātte" - "she/he is called", is a special, archaic passive form integral to the world, which is only applicable to the verb "hātan" - "to call". The active form of the verb, e.g. "þū hātest", means "you call" rather than "you are called". This unique archaic passive form could also be in the past tense. Other verbs use the gerund "ƿesan" - "to be" or the verb "ƿeorðan" - "to become", with the past participle, to express the passive.

Method 2
"Hƿæt is þīn nama?" - "What is your name?"

"Mīn nama is Mǣðhilde" - "My name is Matilda."


text:
User talk:2600:100C:B047:2095:6868:FCF4:8650:6977

Stalking


text: User talk:185.65.253.102

title: User talk:185.65.253.102


text: Beginners Guide to Ladino/Printable version


text: Cosmetic Science/Printable version

title: Cosmetic Science/Printable version


text: Ceramicware Defects Handbook/Printable version


text:
Heliciculture/History

 Snail cultivation or Heliciculture  is a branch of agriculture known since Roman times. In the ancient world snails were called cochlea, like the Latin word for a kind of spoon, which is what their shells were used for. The Roman were very much after the tasty snails, had them picked up in Liguria and fattened in cochlearia - snail gardens, until they could be prepared as food. For example served in milk they were popular because of their stimulating effect, as Pliny and Varro write about the snail.

The Roman Empire's area of influence increasing so did the distribution of snails and snail recipes until into the furthest regions of Europe and the Mediterranean. Snail shells often are found in ancient kitchen waste heaps that are excavated around former Roman settlements. Even today the snail Helix pomatia is called the Roman snail, as it was most probably in Roman times, that it was introduced on the British Isles.

That should not lead to the assumption that the consumption of snails had not a much older history. Today it is though that the common brown garden snail (Cornu aspersum) had already been introduced to the British Isles long before the Romans, in Celtic times, from France. Greeks, Phoenicians and other pre-Roman cultures in the Mediterranean have certainly consumed snails and other molluscs. Sea food in general, but also terrestrial snails are until today a constant part of Mediterranean cuisine.

The Middle Ages brought with them another way of looking at snails and heliciculture. Snails have got the crucial advantage to be neither fish nor meat, so they could be eaten during the time of Lent. Consequently most monasteries also had a snail garden, where the monks could keep the tasty snails, to eat them with an equally monasterial hump of beer.

At that time, though, the monks were not the only people to eat snails. Snails as well were food for the poor. Snails were for free, they could be picked in nature, and they were (and are today) very nutritive and rich. That is probably how snail gardens came into existence in the German region of the Swabian Mountains, from where they have been described until the last century.

In addition to own consumption trade soon was another option. Especially the fat lid snails were sold on the markets as a natural conserve. One or the other hilarious story was apt to arise, for example the story goes that once some farmers set off to the market with a wagon full of lid snails to be sold. On the way to the market they naturally stopped at the one or other pub, which last so long that by the time the farmers finally reached the market, the snails had woken up and left the wagon. Together with trade, of course, also came cultivation. Where for own consumption it was sufficient to pick up the snails, keep them in snail gardens to fatten them and then eat especially the fat lid snails, for a successful trade, snails had to be fatter, tastier and better than all others. From that time came also the idea to feed the snails with a diet of special herbs that gave them an especially fine taste.

There was also a place in that time's medicine for snails. It was well known, that a cure against cough and other breast problems could be produced from snails, as well as a remedy against consumption.

The success of Swabian snail merchants speaks volumes: On the waterway down the Danube River up to 500 tonnes of lid snails in barrels were transported by special transport boats, the Ulm boxes, to Vienna. There the snails were sold on the markets and the way back (600 kilometres at least) was covered on foot, together with the children, inevitable to the famous Viennese charm. There was a roaring trade with snails between Swabia and Vienna until well into the 18th century.

Later the main target of snail trade moved towards Paris, where snails could be transported overland. Even in 1908 the Swabian village of Guttenstein alone sold 4 millions of snails to Paris at a price of 4 to 5 marks per thousand.

While lid snails accompanied Napoleon's columns on their campaigns as natural conserves, the coming up of modern conservation techniques at the beginning of the 20th century put an end to the Swabian snail trade. Today snails are mostly imported from Eastern Europe or even from Africa and Asia.

Snails today are though to be an haute cuisine delicacy. Peasant recipes like snail dumplings, snail sausages or snails with horseradish and cabbage from 18th and 19th century Austria today are forgotten. A proverb from Styria tells, though, that a man was especially capable in the bedchamber, provided he had eaten snails before. This probably should not be forgotten.

But even today there is a future for the trade in snails. In France snails never lost their role as a meal for everyone. In the Germany, Switzerland and Austria - in the South more than in the North - snails win back a certain importance. Rural restaurants in Swabia, but also one or the other star chef rediscovered historical recipes or invented their own. So it happens there are "snails marinated with shrimps on rocket and baked tomatoes" (from the restaurant Krone (the crown) in Nersingen-Unterfahlheim).

title: Heliciculture/History


text:
Heliciculture/Economic Impact

In the United States of America
U.S. imports of snails were worth more than $4.5 million in 1995 and came from 24 countries. This includes preserved or prepared snails and snails that are live, fresh, chilled, or frozen. Major exporters to the U.S. are France, Indonesia, Greece and China. The U.S. exported live, fresh, chilled, or frozen snails worth $55,000 to 13 countries; most were shipped to Japan, the Netherlands, and the United Kingdom. Individual statistics are not available for U.S. exports of prepared or processed snails from the U.S. Department of Commerce.

title: Heliciculture/Economic Impact


text:
Heliciculture/List of Edible Snails

Edible land snails range in size from about one millimeter long to the giant African snails, which occasionally grow up to 312mm (1 foot) in length. "Escargot" most commonly refers to either Helix aspersa or to Helix pomatia, although other varieties of snails are eaten. Achatina fulica, a giant African snail, is sliced and canned and passed off on some consumers as escargot. Terms such as "garden snail" or "common brown garden snail" are rather meaningless since they refer to so many types of snails, but they sometimes mean H. aspersa.

 * Helix aspersa Muller is also known as the French "petit gris," "small grey snail," the "escargot chagrine," or "La Zigrinata." The shell of a mature adult has four to five whorls and measures 30 to 45mm across. It is native to the shores of the Mediterranean and up the coast of Spain and France. It is found on many British Isles, where the Romans introduced it in the first century A.D. (Some references say it dates to the Early Bronze Age.) In the early 1800's the French brought it into California where it has become a serious pest. These snails are now common throughout the U.S. It was introduced into several Eastern and Gulf states even before 1850 and, later introduced into other countries such as South Africa, New Zealand, Mexico, and Argentina. H. aspersa has a life span of 2 to 5 years. This species is more adaptable to different climates and conditions than many snails, and is found in woods, fields, sand dunes, and gardens. This adaptability not only increases H. aspersa's range, but it also makes farming H. aspersa easier and less risky.

 * Helix pomatia Linne measures about 45mm across the shell. It also is called the "Roman snail," "apple snail," "lunar," "La Vignaiola," the German "Weinbergschnecke," the French "escargot de Bourgogne" or "Burgundy snail," or "gros blanc." Native over a large part of Europe, it lives in wooded mountains and valleys up to 2,000 meters (6,000 feet) altitude and in vineyards and gardens. The Romans may have introduced it into Britain. Immigrants introduced it into the U.S. in Michigan and Wisconsin. Many prefer H. pomatia to H. aspersa for its flavor and its larger size, as the "escargot par excellence."

 * Otala lactea or Helix lactea is sometimes called the "vineyard snail," "milk snail," or "Spanish snail." The shell is white with reddish brown spiral bands and measures about 26 to 35mm in diameter. Many think it tastes better than H. aspersa.

 * Iberus alonensis--the Spanish "cabretes" or "xona fina"--measures about 30mm across the shell.

 * Cepaea nemoralis--Helix nemoralis, the "wood snail," or the Spanish "vaqueta,"-- measures about 25mm across the shell. It inhabits Central Europe and was introduced into and inhabits many U.S. states, from Massachusetts to California and from Tennessee to Canada. Its habitat ranges widely from woods to dunes. It mainly eats dead plant material, but it likes nettles and buttercups and will eat dead worms and dead snails.

 * Cepaea hortensis, or Helix hortensis, the "garden snail," measures about 20mm across the shell and has distinct dark stripes. It is native to central and northern Europe. Introduced into Maine, Massachusetts, and New Hampshire in colonial times, it never became established in these states. Its habitat varies like C. nemoralis, but C. hortensis is found in colder and wetter places than nemoralis. Their smaller size and some people's opinion that snails with striped shells do not taste as good make hortensis and nemoralis less popular.

 * Otala punctata or Archelix punctata, called "vaqueta" in some parts of Spain, measures about 35mm across the shell.

 * Otala vermiculata--also called Eobania v. or Helix v., the "vinyala," "mongeta," or "xona"--measures about 25mm. It is found in Mediterranean countries and was introduced into Louisiana and Texas.

 * Helix lucorum, sometimes called "escargo turc," measures about 45mm across the shell. It is found in central Italy and from Yugoslavia through the Crimea to Turkey and around the Black Sea.

 * Helix adanensis comes from around Turkey.

 * Helix aperta measures about 25mm. Its meat is highly prized. It is native to France, Italy, and Mediterranean countries and has become established in California and Louisiana. Sometimes known as the "burrowing snail," it is found above ground only during rainy weather. In hot, dry weather, it burrows three to six inches into the ground and becomes dormant until rain softens the soil.

 * Theba pisana--also called the "banded snail"or the "cargol avellanenc"--measures about 20mm and lives on dry, exposed sites, usually near the sea. Native to Sicily, it has been spread to several European countries, including England. This snail is a serious garden pest and is the "white snail" that California once eradicated by using flamethrowers to burn off whole areas. In large numbers, up to 3,000 snails per tree, it can ravage a garden in 24 hours and a citrus or other crop in a couple of nights.

 * Sphincterochila candidisima or Leucochroa candidisima, the "cargol mongeta," or "cargol jueu" measures about 20mm.

 * Achatina fulica, one of several giant African snails, grows up to 326mm (one foot) long. Its origin is South of the Sahara in East Africa. This snail was purposely introduced into India in 1847. There was an unsuccessful attempt to establish it in Japan in 1925. It has been purposely and accidentally transported to other Pacific locations and was inadvertently released in California after World War II, in Hawaii, and later in North Miami Florida in the 1970's. In many places, it is a serious agricultural pest that causes considerable crop damage. Also, due to its large size, its slime and fecal material create a nuisance as does the odor that occurs when something like poison bait causes large numbers to die. The U.S. has made considerable effort to eradicate Achatina. The U.S. Department of Agriculture (USDA) bans the importation of, and it is illegal to possess, live giant African snails.

"There is no such thing as the giant African or West African snail since there are many genera containing numerous species. . . . For instance, the giant snail in Ghana is taken to mean Achatina Achatina (Linne), but in Nigeria this might refer to Arachachatina Marginata (Swainson), and in East Africa to Achatina fulica Bodich. There are, therefore, several giant land snails in Africa, and not just one species." (3)

title: Heliciculture/List of Edible Snails


text:
Heliciculture/Mating and Egg Laying

General
Snails are hermaphrodites. Although they have both male and female reproductive organs, they must mate with another snail of the same species before they lay eggs. Some snails may act as males one season and as females the next. Other snails play both roles at once and fertilize each other simultaneously. When the snail is large enough and mature enough, which may take several years, mating occurs in the late spring or early summer after several hours of courtship. Sometimes there is a second mating in summer. (In tropical climates, mating may occur several times a year. In some climates, snails mate around October and may mate a second time 2 weeks later.) After mating, the snail can store sperm received for up to a year, but it usually lays eggs within a few weeks. Snails are sometimes uninterested in mating with another snail of the same species that originated from a considerable distance away. For example, a H. aspersa from southern France may reject a H. aspersa from northern France.

Helix Pomatia
Snails need soil at least 2 inches deep in which to lay their eggs. For H. pomatia, the soil should be at least 3 inches deep. Keep out pests such as ants, earwigs, millipedes, etc. Dry soil is not suitable for the preparation of a nest, nor is soil that is too heavy. In clay soil that becomes hard, reproduction rates may decrease because the snails are unable to bury their eggs and the hatchlings have difficulty emerging from the nest. Hatchability of eggs depends on soil temperature, soil humidity, soil composition, etc. Soil consisting of 20% to 40% organic material is good. Keep the soil 65 F to 80 F, best around 70. Maintain soil moisture of 80%. One researcher removes eggs immediately after they are deposited, counts them, then keeps them on moist cotton until the eggs hatch and the young start to eat. Snails lose substantial weight by laying eggs. Some do not recover. About one-third of the snails will die after the breeding season.

H. pomatia eggs measure about 3 mm in diameter and have a calcareous shell and a high yolk content. H. pomatia lays the eggs in July or August, 2 to 8 weeks after mating, in holes dug out in the ground. (Data varies widely on how long after mating snails lay eggs.) The snail puts its head into the hole or may crawl in until only the top of the shell is visible; then it deposits eggs from the genital opening just behind the head. It takes the snail 1 to 2 days to lay 30 to 50 eggs. Occasionally, the snail will lay about a dozen more a few weeks later. The snail covers the hole with a mixture of the slime it excretes and dirt. This slime, which the snail excretes to help it crawl and to help preserve the moisture in its soft body, is glycoprotein similar to eggwhite.

Fully-developed baby H. pomatia snails hatch about 3 to 4 weeks after the eggs are laid, depending on temperature and humidity. Birds, insects, mice, toads and other predators take a heavy toll on the young snails. The snails eat and grow until the weather turns cold. They then dig a deep hole, sometimes as deep as 1 foot, and seal themselves inside their shell and hibernate for the winter. This is a response to both decreasing temperature and shorter hours of daylight. When the ground warms up in spring, the snail emerges and goes on a binge of replacing lost moisture and eating.

Helix Aspersa
H. aspersa eggs are white, spherical, about 3 mm in diameter and are laid 5 days to 3 weeks after mating. (Data varies widely due to differences in climate and regional variations in the snails' habitats.) H. aspersa lays an average of 85 eggs in a nest that is 1- to 1 1/2-inches deep. Data varies from 30 to over 120 eggs, but high figures may be from when more than one snail lays eggs in the same nest.

In warm, damp climates, H. aspersa may lay eggs as often as once a month from February through October, depending on the weather and region. Mating and egg-laying begin when there are at least 8 hours of daylight and continue until days begin to get shorter. In the United States, longer hours of sunlight that occur when temperatures are still too cold will affect this schedule, but increasing hours of daylight still stimulate egg laying. If warm enough, the eggs hatch in about 2 weeks, or in 4 weeks if cooler. It takes the baby snails several more days to break out of the sealed nest and climb to the surface. In a climate similar to southern California's, H. aspersa matures in about 2 years. In central Italy, H. aspersa hatches and emerges from the soil almost exclusively in the autumn. If well fed and not overcrowded, those snails that hatch at the start of the season will reach adult size and form a lip at the edge of their shell by the following June. If you manipulate the environment to get more early hatchlings, the size and number of snails that mature the following year will increase. In South Africa, some H. aspersa mature in 10 months, and under ideal conditions in a laboratory, some have matured in 6 to 8 months. Most of H. aspersa's reproductive activity takes place in the second year of its life.

Achatina fulica
By contrast, one giant African snail, Achatina fulica, lays 100 to 400 elliptical eggs that each measure about 5 mm long. Each snail may lay several batches of eggs each year, usually in the wet season. They may lay eggs in holes in the ground like H. pomatia, or lay eggs on the surface of a rocky soil, in organic matter, or at the base of plants. In 10 to 30 days, the eggs hatch releasing snails about 4 mm long. These snails grow up to 10mm per month. After 6 months, the Achatina fulica is about 35mm long and may already be sexually mature. Sexual maturity takes 6 to 16 months, depending on weather and the availability of calcium. This snail lives 5 or 6 years, sometimes as many as 9 years.

title: Heliciculture/Mating and Egg Laying


text:
Heliciculture/Growth

Within the same snail population and under the same conditions, some snails will grow faster than others. Some will take twice as long to mature. This may help the species survive bad weather, etc., in the wild. However, a snail farmer should obviously select and keep the largest and fastest maturing snails for breeding stock. Sell the smaller snails. By selecting only the largest, the average size of the snail may increase significantly in only a couple of generations. Most of the differences in growth are probably due to environmental factors including stocking density. However, to whatever extent these differences are genetic, you might as well breed large, fast-growing snails instead of small, slower-growing ones.

Several factors can greatly influence the growth of snails including: population density; stress [snails are sensitive to noise, light, vibration, unsanitary conditions, irregular feedings, being touched, etc.]; feed; temperature and moisture; and the breeding technology used.

H. aspersa requires at least 3% to 4% calcium in the soil (or another source of calcium) for good growth. Most snails need more calcium in the soil than H. aspersa. Low calcium intake will slow the growth rate and cause the shell to be thinner. Calcium may be set out in a feeding dish or trough so the snails can eat it at will. Food is only one calcium source. Snails may eat paint or attack walls of buildings seeking calcium, and they also will eat dirt.

A newborn's shell size depends on the egg size since the shell develops from the egg's surface membrane. As the snail grows, the shell is added onto in increments. Eventually the shell will develop a flare or reinforcing lip at its opening. This shows that the snail is now mature; there will be no further shell growth. Growth is measured by shell size, since a snail's body weight varies and fluctuates, even in 100% humidity. The growth rate varies considerably between individuals in each population group. Adult size, which is related to the growth rate, also varies, thus the fastest growers are usually the largest snails. Eggs from larger, healthier snails also tend to grow faster and thus larger.

Dryness inhibits growth and even stops activity. When it becomes too hot and dry in summer, the snail becomes inactive, seals its shell and estivates (becomes dormant) until cooler, moister weather returns. Some snails estivate in groups on tree trunks, posts, or walls. They seal themselves to the surface thus sealing up the shell opening.

title: Heliciculture/Growth


text:
Heliciculture/Farming Snails

Successful snail culture requires the correct equipment and supplies, including: snail pens or enclosures; devices for measuring humidity (hygrometer), temperature (thermometer), soil moisture, and light (in foot candles); a weight scale and an instrument to measure snail size; a kit for testing soil contents; and a magnifying glass to see the eggs. You also may need equipment to control the climate (temperature and humidity), to regulate water (e.g., a sprinkler system to keep the snails moist and a drainage system), to provide light and shade, and to kill or keep out pests and predators. Some horticultural systems such as artificial lighting systems and water sprinklers may be adapted for snail culture. You will have better results if you use snails of the same kind and generation. Some recommend putting the hatchlings in another pen.

Four Systems of Snail farms:
 * Outdoor Pens.
 * In buildings with a controlled climate.
 * In closed systems such as plastic tunnel houses or "greenhouses."
 * In addition, snails may breed and hatch inside in a controlled environment and then (after 6 to 8 weeks) may be placed in outside pens to mature.

Climate: A mild climate (59-75 F) with high humidity (75% to 95%) is best for snail farming, though most varieties can stand a wider range of temperatures. The optimal temperature is 70 F for many varieties. When the temperature falls below 45 F, snails hibernate. Under 54 F the snails are inactive, and under 50 F, all growth stops. When the temperature rises much above 80 F or conditions become too dry, snails estivate. Wind is bad for snails because it speeds up moisture loss, and snails must retain moisture.

Moisture: Snails need damp, not wet, environments. Although snails need moisture, you must drain wet or waterlogged soil to make it suitable for them. Similarly, rainwater must run off promptly. Snails breathe air and may drown in overly wet surroundings. A soil moisture content of 80% of capacity is favorable. In the hours of darkness, air humidity over 80% will promote good snail activity and growth.

Ninety-nine percent of snail activity, including feeding, occurs in the cool, dark nighttime, with peak activity taking place 2 to 3 hours after darkness begins. The cooler temperature stimulates activity, and the nighttime dew helps the snail move easily. They hide in sheltered places during most of the day. If necessary, use misting sprayers, like those used for plant propagation, in dry climates to maintain adequate humidity and moisture levels.

Soil: Use a good medium soil that has neither a lot of sand nor too much clay. Snails cannot dig into hard, dry clay, and soils with too much sand or too little water. Soil that contains 20% to 40% organic matter is good. The soil should be similar to that of a garden in which green, leafy vegetables thrive. If your snail farm contains plants, keep them wet and properly care for them. Regularly remove any weeds. Neutralize soil that is too acidic with lime to make it suitable (at about pH 7). Besides the pH value of the soil, calcium must be available either from the soil or another readily available source, since snail shells are 97% to 98% calcium carbonate. If in doubt, you can add a little ground limestone. One researcher treats the soil with polyacrylamide at the rate of 12.5cc of a 160-g M.A./one preparation in 250cc of water per kilogram of dry soil. This stabilization treatment helps the soil structure resist washing. This allows regular cleaning without destroying the crumb structure of the soil that is beneficial for egg laying.

Snails dig in soil and ingest it. Good soil favors snail growth and provides some of their nutrition. Lack of access to good soil may cause fragile shells even when the snails have well-balanced feed; the snails growth may lag far behind the growth of other snails on good soil. Snails will often eat feed, then go eat dirt. Sometimes, they will eat only one or the other. This may be one reason that you should not crowd too many snails into too small a pen. The soil, unless frequently changed, will become fouled with mucus and droppings. Chemical changes also may occur in the soil. A mixture of peat, clay, compost, CaCO3 at pH 7 makes a very good soil. Leaf mold at pH 7 works almost as well. Organic matter in the soil seems as important as carbonates. Soils that are richest in exchangeable calcium and magnesium stimulate growth best. Usable carbonates and total calcium are important. Calcium may be added to the soil at the rate of 10 pounds per 100 square feet. Calcium may also be set out in a feeding dish or trough so the snails can eat it at will.

title: Heliciculture/Farming Snails


text:
Heliciculture/Pens and Enclosures

The U.S. Animal and Plant Health Inspection Service (APHIS) Standards for Snail-Rearing Facilities were revised March 2001 and are available at the USDA website

Enclosures for snails are usually long and thin instead of square. This allows you to walk around (without harming the snails) and reach in the whole pen. The enclosure may be a trough with sides made of wood, block, fiber cement sheets, or galvanized sheet steel. Cover it with screen or netting. The covering will confine the snails and keep out birds and other predators. Fences or walls are usually 2-feet high plus at least 5 inches into the ground. Fencing made of galvanized metal or hard-plastic sheets helps keep out some predators. A cover will protect against heavy rain. Shade (which may be a fine mesh screen) on warm winter days helps keep the snails dormant. Use 5 mm mesh or finer for pen screens or fences. Pens containing baby snails will need a finer mesh.

Snails like hiding places, especially during the warm daytime. For example, purchase plastic soil drainage pipes from the local garden center, split them in two lengthwise, and stack one layer one way and the next layer at a right angle. This will provide shelter and will increase by 50% the number of snails you can put in the pen.

A sprinkler system will ensure moisture when needed. Turn it on at sunset. If turned on early in the day, the moisture may drive snails out into hot sunshine. Monitor temperature and humidity using a thermometer and a hygrometer.

Although you can use fencing for the enclosure's sides, the bottom, if not the ground or trays of dirt, must be a surface more solid than screening. A snail placed in a wire-mesh-bottom pen will keep crawling, trying to get off the wires and onto solid, more comfortable ground.

Preventing escapes: In an open pen, curve the top of the fences inward in a half circle to confine the vineyard snail. H. aspersa will escape from such an open pen, so you could use an electric fence to contain them. [The electric fence top has two or more thin wires that are 2 to 4 mm apart. Each wire carries the opposite charge of the wire next to it. Use a battery or transformer to supply 4 to 12 volts to the wire. A snail will get a mild shock and retract when it crawls over a wire and touches a second wire.]

Another technique to confine snails is to bend the fence top inward into a sharp "V" shape with about a 20 degree angle. The snail's shell will hit the bent-back part of the screen before he can reach up and start crawling on it. This blocks him, and the angled screen automatically compensates for the size of the snail.

Another alternative, especially handy for solid wall enclosures, is to attach to the wall a horizontal piece of screen that projects inward several inches over the enclosure. Make the screen with material like nylon monofilament that is moderately stiff and springy yet easily flexible. On the inside edge of the screen, remove the cross fibers until you've created a fringe several inches wide. As the would-be escapee crawls on the underside of the screen and moves out onto the fringe, his weight pulls several individual fibers down. One by one, another fiber gets away from the snail and springs back up out of reach. Eventually the snail is dangling by a thread. He then falls because the surface area is not big enough to crawl on.

Since snails usually will not cross a copper band, another solution is to top the fence with 3-inch-wide (or wider) copper band. You could bend the band so that part of it faces inward and is parallel to the pen floor. If the band is placed too close to the ground, rain may wash soil against the copper and leave a residue that may enable the snail to cross it. Also, be sure to bury the bottom of the fence deep enough into the ground so that the snails don't dig under it.

Pens with gardens: An alternate method is to make a square pen with a 10-foot-square garden in it. Plant about six crops, e.g., nettles and artichokes, inside the pen. The snails choose what they want to eat. If it has not rained, turn sprinklers on for about 15 minutes at dusk, unless the snails are dormant. A disadvantage to this method is that, if the snails are not mature at the end of the year, it is difficult to replant fresh plant crops in the pens.

Plastic tunnels make cheap, easy snail enclosures, but it is difficult to regulate heat and humidity. The tunnel will be 10 to 20 warmer than the outside, and snails become dormant as the temperature climbs above 80 F.

Indoor pens: With snails raised indoors under controlled conditions, reproduction varies according to the geographic origin of the breeding stock. For example, one researcher found that H. aspersa snails from Brittany seem to do better indoors than snails from another region. To breed snails indoors, keep the temperature at 70 F. and the relative humidity at 80% to 90%; some sources say 95%. Another source recommends 75% humidity by day and 95% at night. The Center for Heliciculture once recommended 65-75% humidity during the day and 85-95% at night at 68 F. In any event, avoid humidity higher than 95% (some say 90%) for any length of time. Excessive humidity can kill snails. Optimum temperature and relative humidity depend on several things, including the snail variety and even where breeding stock was gathered. For H. aspersa, the optimum temperature for hatching eggs seems to be 68 F at 100% relative humidity. The second best temperature/humidity combination depends on where the snails came from and results can drop drastically to 0% hatching at 62.6 F and 100% humidity. Err on the side of a few degrees warmer or a small percentage dryer. Do not keep the soil wet when the humidity is maintained at 100%, as the eggs will absorb water, swell up, and burst.

Use fluorescent lights to give artificial daylight. Different snails respond differently to day length. The ratio of light to darkness influences activity, feeding, and mating andegg-laying. Eighteen or more hours of light apparently stimulate H. aspersa growth, while less than 12 hours inhibit it. Some snail species may associates the long hours of light with the start of summer--the peak growing season. Eighteen hours of daylight also appear optimal for breeding (mating and egg laying), but snails will breed in darkness.

Breeding boxes and cages: Snails can be bred in boxes or cages stacked several units high. Use an automatic sprinkler system to provide moisture. Breeding cages should have a feed trough and a water trough. Plastic trays that are a couple of inches deep are adequate; deeper water troughs increase the chance of snails drowning in them. These trays may be set on a bed of small gravel. Fill small plastic pots, e.g., flower pots about 3 inches deep, with sterilized dirt (or a loamy pH neutral soil) and set them in the gravel to give the snails a place to lay their eggs. Remove and replace each pot after the snails lay eggs. (Set one pot inside another so that you can easily lift one out without shifting the gravel.)

After the snails have laid their eggs, put the pots in a nursery where the eggs will hatch. Keep the young snails in the nursery for about 6 weeks. Then move them to a separate pen as young snails do best if kept with other snails of similar size. Eight hours of daylight is optimal for young snails.

The following is an example of starting H. pomatia in boxes: Build wooden boxes measuring 25 by 35cm and 25cm high. Cut a 6cm-diameter hole (to drain excess moisture) in the bottom and cover the hole with plastic screening, well secured. Cover a frame with plastic screening to create the box lid. The lids either must open or be removable. Keep the boxes on shelves so they are easily accessible. Fill the boxes one-third full with loose, uncompacted garden soil baked to kill all organisms (insects, nematodes, bacteria, etc.). [Use soil that does not have fertilizer or chemicals in it.] Partially cover the soil with moss, but leave enough room for the snails to crawl around on the dirt. Sprinkle water on the moss.

Move to boxes (three per box) those snails in the outdoor pen that are starting to make holes in which to lay their eggs. After the snails lay eggs, return them to the outside pen. The soil in the boxes must not dry out. Always keep the moss slightly moist. Too much moisture is dangerous, however, as the eggs may swell up and burst. The eggs hatch in about 25 days, but the baby snails remain in the egg "shells." They then work their way out of the nest for about 10 additional days before they appear on the moss and on the sides of the box. Snails on the wood sides of the box are in danger of drying out and must be carefully removed and put on the moss. Shells are very fragile at this time.

Feed the baby snails tender lettuce leaves (Boston type, but head type is probably just as good.) [This description does not include a water trough, but the authors assume there is one. The snails should have water available.]

Three weeks after the snails appear on the moss, carefully remove the baby snails and put them together in a temporary container. Carefully remove the moss and dirt, watching for any more baby snails. Replace the dirt and moss with fresh (sterilized/baked) dirt and fresh moss. Count and return the snails to the box.

The young snails can be kept over winter in these boxes. Stack the boxes in a cool room protected from frost. The room should never get colder than 32 F nor warmer than 37.4 F. Snails will become active again the following spring when the temperature rises above 41 F. Feed them for 4 weeks. They should now average about 8 mm. Move them to a pen, carefully clean and dry the boxes, and prepare the boxes for the new season. H. pomatia matures in 18 months to 4 years.

Mixed system: A variation of the method above is to let the snails lay the eggs in the outdoor pen, then carefully transfer the eggs to the boxes. [The other steps are the same.] In the pen, look for snails that have dug holes and are in them laying eggs. The tip of their shell will be visible. Stick a marker in the ground next to the hole. When the snail is finished and leaves, use a garden trowel to dig up the eggs and move them. This task is difficult. The eggs can be both physically damaged and covered with dirt.

Example: Five stages of snail raising

Some who raise H. aspersa separate the five stages: reproduction, hatching, young, fattening, and final fattening.

In a typical example, the breeding box has concrete sides, soil with earthworms (to cleanse the soil) on the bottom, vegetation, curved tiles to provide shelter, feeders, and a chicken waterer. Mosquito netting or screening covers the top. These breeding boxes may be outside, or you may get better results when the boxes are inside a greenhouse--as long as the greenhouse does not get too hot or too dry. One researcher reported that in outdoor boxes, each breeder snail had about seven young. In greenhouses, each breeder snail had about 9 to 12 young. The researcher felt that under better weather conditions than those he had that year, each adult breeder snail would have produced 15 young snails.

Fattening pens may be outside or in a greenhouse. High summer temperatures and insufficient moisture cause dwarfing and malformations of some snails. This is more a problem inside greenhouses if the sun overheats the building. A sprinkler system (e.g., a horticultural system or common lawn sprinklers) can supply moisture. Make sure excess water can drain.

Fattening pens may contain 2-foot by 3-foot pieces (or other convenient size) of heavy plastic sheets, hung from boards resting on a rack that lets the tips of the plastic sheets just touch the ground. The plastic sheets are about 4 inches apart. The sheets give the snails a resting and hiding place. Feeders may be located on the rack that supports the plastic sheets.

Put a layer of coarse sand and topsoil with earthworms on the fattening pen's bottom. The worms help clean up the snail droppings.

You can put snails that hatched the previous summer in a chilled room for hibernation over winter. Then, about the 1st of April, (adjusted for your local climate), move them to the final fattening pen. If you have several fattening pens, put the smaller snails in one, medium in another, large in another. Do not exceed one-third pound of H. aspersa snails per square foot of pen. Since snails lose weight when they estivate in summer, some growers do not stock pens by weight but by count. For H. aspersa, 10 to 12 snails per square foot is about the maximum.

Breeding pens can be set up just like the fattening pens or the fattening pens can be used as breeding pens after you harvest the mature snails. Harvest some snails and leave some to breed.

title: Heliciculture/Pens and Enclosures


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Heliciculture/Cannibalism by Hatchlings

The first snails to hatch eat the shells of their eggs. This gives them needed calcium for their shells. They may then begin eating unhatched eggs. If the snail eggs are kept at the optimum temperature, 68 F (for some varieties), and if none of the eggs lose moisture, most eggs will hatch within 1 to 3 days of each other. Cannibalism also will be low. If hatching extends over a longer period, cannibalism may increase. Some eggs eaten are eggs that were not fertile or did not develop properly, but sometimes, properly developing embryos might be eaten. A high density of "clutches" of egg masses increases the rate of cannibalism, as other nearby egg masses are more likely to be found and eaten. Snail egg has 12 to 20 times the protein of salad. The protein helps the baby snails start developing quickly and be healthier. Snail egg is an excellent starter food for newly hatched snails, but they tend to only eat eggs of their own species.

title: Heliciculture/Cannibalism by Hatchlings


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Heliciculture/Gathering Snails

Besides farming snails, it is possible to gather them free from artichoke, kiwifruit, avocado, and citrus growers in some areas. The growers might pick the snails for you for a fee. In citrus groves where copper bands have been placed around the tree trunks, the snails will crawl up the tree to feed on the leaves. They will stop when they come to the copper band and will remain there for days. The snails gathered just below the band are easy to pick off.

Snails gathered in the wild to stock a snail farm may have a high mortality rate as they adjust to the new conditions. These snails may have consumed poison baits, agricultural chemicals, or poisonous plants (e.g., nightshade); therefore, you should not immediately use them. Put them in a pen and feed them for at least 3 days to purge their system of any toxins and to give them a chance to die if they have consumed a lethal dose. If they are still healthy after 3 or 4 days, they should be O.K.. Withhold all food, except water, for the last 1 to 2 days.

title: Heliciculture/Gathering Snails


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Heliciculture/Feeding

Feeding season is April through October, (or may vary with the local climate), with a "rest period" during the summer. Do not place food in one small clump so that there is not enough room for all the snails to get to it. Snails eat solid food by rasping it away with their tongues. Feeding activity depends on the weather, and snails may not necessarily feed every day. Evening irrigation in dry weather may encourage feeding since the moisture makes it easier for the snails to move about.

Put the breeding snails in the breeding pens in April or early May. Feed until mid June when mating begins and the snails stop feeding. Snails resume eating after they lay eggs. Once snails have laid their eggs, you can remove the adult snails. This leaves more food and less crowding for the hatchlings.

Snails of the same species collected from different regions may have different food preferences. Some foods that snails eat are: Alyssum, fruit and leaves of apple, apricot, artichoke (a favorite), aster, barley, beans, bindweed, California boxwood, almost any cabbage variety, camomile, carnation, carrot, cauliflower, celeriac (root celery), celery, ripe cherries, chive, citrus, clover, cress, cucumbers (a favorite snail food), dandelion, elder, henbane, hibiscus, hollyhock, kale, larkspur, leek, lettuce (liked, and makes good snails), lily, magnolia, mountain ash, mulberry, mums, nasturtium, nettle, nightshade berries, oats, onion greens, pansy, parsley, peach, ripe pears, peas, petunia, phlox, plum, potatoes (raw or cooked), pumpkins, radish, rape, rose, sorrel, spinach, sweet pea, thistle, thornapple, tomatoes (well liked), turnip,wheat, yarrow, zinnia. They will eat sweet lupines, but will reject bitter lupines and other plants with high quinolizidine alkaloids. Snails also avoid plants that produce other defensive chemicals, defensive stem hairs, etc.

Snails usually prefer juicy leaves and vegetables over dry ones. If you feed snails vegetable trimmings, damaged fruit, and cooked potatoes, promptly remove uneaten food as it will quickly spoil. You may supply bran that is wet or sprinkle dry bran over leafy vegetables. The diet may consist of 20% wheat bran while 80% is fruit and vegetable material. Some growers use oats, corn meal, soybean meal, or chicken mash. Laying mash provides calcium, as does crushed oyster shells. Snails also may eat materials such as cardboard (but do not purposely feed it to them); they can eat through shipping cartons and escape. Snails may sometimes eat, within a 24-hour period, food equal to 10%, and occasionally as much as 20%, of their body weight. Active snails deprived of food will lose more than one-third of their weight before they starve to death--a process that takes 8 to 12 weeks. Estivating snails can survive much longer.

Supply calcium at least once a week if it is not available in the soil. It should not contain harmful salts or be so alkaline as to burn the snails. Mix calcium with wet bran or mashed potatoes and serve on a pan; this will keep any leftover food from rotting on the ground.

Some researchers use chicken mash for feed. You can cut a plastic pipe in half lengthwise to make two troughs which can be used as feeders for mash. Mix laying mash (used for egg-producing hens) into the feed to provide calcium for the snails' shells. Commercial chicken feeding mash is around 16% to 17% protein, from fish meal and meat meal, making it good for growing snails. Supplying mash to hatchlings might reduce cannibalism. Two feeds that snails like and that promote good growth are: (A) broiler finisher mash consisting of 7% broiler concentrate, 58% corn, 16% soya, 18% sorghum, 7 % limestone flour (40% Ca); and (B) chicken feed (pellets) for layers consisting of 5% layer concentrate, 10%, corn, 15% soya, 20% sorghum, 44% barley, 6% limestone flour (40%Ca).

Pellets are fine for larger snails, but mash is better for younger ones. Partially crush pellets if you feed them to young snails. Snails do not grow well if rabbit pellets are their primary diet. Snails show a distinct preference for moist feed. Ensure easy access to enough water if you feed snails dry mash.

Be sure to frequently clean the feed and water dishes. The amount of feed a snail eats depends very much on air humidity and on the availability of drinking water. You can serve clean drinking water in a shallow container to reduce the risk of the snail drowning. Some types of chicken waterers may be suitable. Other factors (e.g., temperature, light intensity, food preferences versus food supplied, etc.) also affect feeding. A compromise, until you find the optimum feed, is to feed half green vegetable material and half chicken feed/grain/animal protein.

Young H. aspersa readily eats milk powder. Its rapid rate of assimilation promotes rapid growth.

title: Heliciculture/Feeding


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Heliciculture/Diseases and Pests

Basic common sense hygiene may prevent the spread of disease or otherwise improve the health and growth rate of snails. For example, remove and replace food daily to prevent spoilage. Earthworms added to the soil will help keep the pen clean.

Snails have many natural predators, including members of all major vertebrate groups, carnivorous snails, ground beetles, leeches and even predatory caterpillars.Parasites, nematodes, trematodes, fungi, and microarthropods may attack snails, and such problems can spread rapidly when snail populations are dense. The bacterium Pseudomonas aeruginosa causes intestinal infections that can spread rapidly in a crowded snail pen. The second disease is caused by the fungus Fusarium, which parasitises their eggs of Helix aspersa. The affected eggs turn reddish-brown and development stops. This disease is commonly referred to as 'rosy eggs disease'.

Watch for predators such as: rats, mice, moles, skunks, weasels, birds, frogs and toads, lizards, walking insects (e.g., some beetle and cricket varieties), some types of flies, centipedes, and even certain cannibalistic snail varieties (such as Strangesta capillacea).

title: Heliciculture/Diseases and Pests


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Heliciculture/Population and Density

Population density also affects successful snail production. Pens should contain no more than six to eight fair-sized snails per square foot, or about four large H. pomatias; or figure one kilogram per square meter (about .2 pounds of snail per square foot), which automatically compensates for the size of the snails. If you want them to breed, best results will occur with not more than eight snails per square meter (.8 snails per square foot). Some sources say that, for H. pomatia to breed, .2 to .4 snails per square foot is the maximum.

Snails tend not to breed when packed too densely or when the slime in the pen accumulates too much. The slime apparently works like a pheromone and suppresses reproduction. On the other hand, snails in groups of about 100 seem to breed better than when only a few snails are confined together. Perhaps they have more potential mates from which to choose. Snails in a densely populated area grow more slowly even when food is abundant, and they also have a higher mortality rate. These snails then become smaller adults who lay fewer clutches of eggs, have fewer eggs per clutch, and the eggs have a lower hatch rate. Smaller adult snails sell for less. Dwarfing is quite common in snail farming and is attributable mainly to rearing conditions rather than heredity factors. Crowding snails is false economy. A recommended rate for H. aspersa is not more than one-third pound per square foot of soil surface for snails that weigh more than 1 gram and not more than .2 pound per square foot for snails that weigh less. (One ounce is about 28 grams.)

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Heliciculture/Shipping Snails

Shipment Selection
Select only active snails for canning, processing or shipping. An inactive snail may be sick or dying. It is best to ship live snails (laws permitting) while dormant, between late Fall and early March, although it is then difficult to be sure they are "active." Inspect each snail to be sure it looks healthy. Put them in a container packed in ice to keep the temperature near (but not below) freezing to keep the snails dormant. When the weather warms up and the snails are active, they cannot be packed so closely in cartons. As live animals, you must handle them humanely. Some sources say not to ship live snails (H. pomatia) after June begins, as they no longer have good flavor. H. aspersa has a fragile shell until it matures and forms a lip, so immature snails are not commercially desirable.

Shipment Preparation
Snails tend not to eat during shipping. Do not provide food, as it will spoil and may make the snails sick or die. Purge the snails' digestive tracts to ensure that they are clear of grit or previously-eaten food. Three or 4 days before transporting, put the snails in a separate container without dirt or other kinds of food. Feed the snails cornmeal or bran for several days. As it passes through the digestive tract, it will clean out previously-eaten food. Stop feeding, but continue to supply water. Clean the pens and snails several times a day to keep out mucus and fecal matter.

Shipping Packages
Shipping cartons must have air holes, preferably screened to prevent escape or injury to the snails. Be careful not to injure snails with wires or staples when closing the carton. Also remember, snails can push upward against a barrier with a force equal to several times their own weight. Enough snails may cause the carton lids to pop off and may even loosen nails.

title: Heliciculture/Shipping Snails


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Heliciculture/Turning Snails into Escargot

Snails are mature when a lip forms at the opening of their shell. Before they mature, their shells are more easily broken, making them undesirable. For H. aspersa, commercial weight is 8 grams or larger.

The nutrient composition of raw snails (per 100 grams of edible portion), according to information from the nutrient databank of France, is:

 * Energy (kcal): 80.5
 * Water (g): 79
 * Protein (g): 16
 * Available carbohydrates (g): 2
 * Fiber (g): 0
 * Fat (g): 1
 * Magnesium (mg): 250
 * Calcium (mg): 170
 * Iron (mg): 3.5
 * Vitamin C (mg): 0

Snails are washed, steamed, shelled, then washed in a vinegar- (or lemon juice) and water-solution before they are canned. Producing a quality canned product is somewhat tricky, and you must take care to prevent food poisoning. To prepare live snails for cooking, remove the membrane, if any, over the shell opening. Soak the snails in enough water to cover them. (Add 1/2-cup salt or 1/4-cup vinegar for every 50 snails.) Mucus will turn the water white. Change the water several times during the 3- to 4-hour soaking. Rinse several times or under running water until no mucus remains. Put snails in cold water and bring to a boil. Boil about eight minutes, then drain and plunge the snails into cold water. Drain. With a needle or small fork, pick the snails out of their shells. Remove the intestine and cut off all black parts. (Some cooks also cut off the head, tail, and all "cartilage or gristle.") Prepare according to your recipe. An alternate method is: Wash the snails well in clear water. Drop into boiling salt water (to which you may add lemon juice and/or herbs), and cook--about 10-15 minutes--until you can easily remove the snails from their shells. Drain and rinse.

Prepare the giant African snail by breaking away the shell, then cutting the foot away from the rest of the body. The traditional way to remove the slime is to rub wood ashes on the snail, then wash the snail (or part of the snail) under running water, then repeat until no slime remains. You may substitute substances like flour (to which you may add salt and vinegar) for ashes. Cut up the foot into convenient-sized pieces. [You may dehydrate the leftover visceral mass, crush it up with the shell, and mix it in poultry feed to make up 10% of your snail feed.] Another source says put the live snails in boiling water for 30 minutes to kill them and to make removal from the shell easy. During boiling, the snails will release a large quantity of mucus. Data varies, but 28% to 46% of the live weight of Achatina is shell.


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Heliciculture/Restrictions and Regulations in the United States

The same snails that some people raise or gather as food also are agricultural pests that cause considerable crop damage. Introduced slug and snail varieties tend to be worse pests than native species, probably due in part to the lack of natural controls. Snail pests attack crops ranging from leafy vegetables to fruits that grow near the ground, such as strawberries and tomatoes, to citrus fruits high up on trees.

The Federal Plant Pest Act defines a plant pest as "any living stage (including active and dormant forms) of insects, mites, nematodes, slugs, snails, protozoa, or other invertebrate animals, bacteria, fungi, other parasitic plants or reproductive parts thereof; viruses; or any organisms similar to or allied with any of the foregoing; or any infectious substances, which can directly or indirectly injure or cause disease or damage in or to any plants or parts thereof, or any processed, manufactured, or other products of plants..." The Animal and Plant Health Inspection Service (APHIS) categorizes giant African snails as a "quarantine significant plant pest." The United States does not allow live giant African snails into the country under any circumstances. It is illegal to own or to possess them. APHIS vigorously enforces this regulation and destroys or returns these snails to their country of origin.

Since large infestations of snails can do devastating damage, many states have quarantines against nursery products, and other products, from infested states. Further, it is illegal to import snails (or slugs) into the U.S. without permission from the Plant Protection and Quarantine Division(PPQ), Animal Plant Health and Inspection Service, U.S. Department of Agriculture. APHIS also oversees interstate transportation of snails. Anyone who plans to "import, release, or make interstate shipments of" snails, must complete APHIS's PPQ Form 526, Application and Permit to Move Live Plant Pests and Noxious Weeds. Submit the form to your State regulatory official. The state will process the request and make a recommendation to APHIS who will then make a decision.

Information on Plant Pest Permits is available at APHIS's web site.

The Food and Drug Administration (FDA) regulates the canning of low-acid foods such as snails. According to FDA, "establishments engaged in the manufacture of Low-acid or Acidified Canned Foods (LACF) offered for interstate commerce in the United States are required. . .to register their facility. . .and file scheduled processes for their products with" the FDA. This does not refer to fresh products. For appropriate forms, contact: LACF Registration Coordinator, HFS-618, Food and Drug Administration, Center for Food Safety and Applied Nutrition, 200 C Street, S.W., Washington, D.C. 20204. Telephone: (202) 205-5282. FAX: (202) 205-4758 or (202) 205-4128.

Improper canning of low-acid meats, e.g., snails, involves a risk of botulism. When canning snails for home consumption, carefully follow canning instructions for low-acid meats to prevent food poisoning.

State laws also may apply to imports into certain states and to raising snails in a given state. Your state also may want to inspect and approve your facility. Thus anyone who plans to raise snails also should check with their State's Agriculture Department.


text: Heliciculture/Printable version

title: Heliciculture/Printable version


text: Vegan and vegetarian phrases/Printable version


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Wikibooks:Collections/Upper digestive system

 * Learning anatomy/Mouth


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User:TimeEngineer/sandbox

Introduction

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text: Template:Kosher Cookbook

title: Template:Kosher Cookbook