In the 1830s, an upholsterer and cabinetmaker named Theodore Alexander Robert Jupe was awarded British Patent No. 6788 for an expandable table design. The round six-seater table contained a particularly ingenious mechanical mechanism that must have astonished citizens of the Georgian era. Before we get into the mechanism, have a look at the table from overhead:
Round Dining Table by Robert Jupe from M.S. Rau Antiques on Vimeo.
Here's what's funny: In my opinion, the auctioneer actually uses the table mechanism incorrectly! Watch the footage from 0:21 to 0:27, and you'll see he turns the table counterclockwise to separate the wedges, which is correct. But after adding the inserts, at 0:44 to 0:48 he rotates the table clockwise to tighten the leaves. I feel he has missed the most important point of the table's mechanism, which is called a Capstan mechanism. Watch the CG animation below to understand how it works:
As you can see, a Capstan mechanism is designed to turn rotary motion into linear motion. As the outer portion of the table is rotated, the central hub does not move, and those curved arms attached to it thus force the triangular-topped pieces to move outwards along the track. However, because of the precise length of the arms, the amount of travel built into the table and the overall geometry of the mechanism, a neat trick is accomplished: Once a certain amount of rotation is achieved, the arms stop pushing outwards, and start pulling inwards.
In other words, I believe that Jupe designed the table so that the rotation happens all in one direction. The user spins the table counterclockwise until the arms reach their maximum extension, at which point s/he drops the inserts in. S/he then continues rotating the table counterclockwise, and the over-rotation of the table acting on the arms then snugs the parts up, by pulling inwards and eating up the clearance.
If Jupe had designed the table to be used in the manner in which the auctioneer operates it, there would have been no need to design in the elegant reverse motion that the arms achieve towards the end of the rotation. He could have saved himself some trouble and simply designed the table to provide maximum clearance between the leaves at the end of its rotation, providing room for the user to drop the extensions in, then required the user to turn the table backwards to snug it up.
That less-elegant solution would probably be acceptable to 99% of designers. But in my opinion it wasn't acceptable to Jupe. It's a shame the auctioneer missed one of those seemingly little design details that I believe the builder considered important.
Again, this is just my opinion. If any of you have, say, degrees in mechanical engineering, I'm particularly curious to hear your thoughts.