The greatest height at which visible clouds ever exist does not exceed ten miles.
Air is about eight hundred and fifteen times lighter than water.
The pressure of the atmosphere upon every square foot of the earth amounts to two thousand one hundred and sixty pounds. An ordinary sized man, supposing his surface to be fourteen square feet, sustains the enormous pressure of thirty thousand two hundred and forty pounds.
The barometer falls one-tenth of an inch for every seventy-eight feet of elevation.
The violence of the expansion of water when freezing is sufficent to cleave a globe of copper of such thickness as to require a force of 27,000 pounds, to produce the same effect.
During the conversion of ice into water one hundred and forty degrees of heat are absorbed.
Water, when converted into steam, increases in bulk eighteen hundred times.
In one second of time--in one beat of the pendulum of a clock light travels two hundred thousand miles. Were a cannon ball shot toward the sun, and were it to maintain full speed, it would be twenty years in reaching it--and yet light travels through this space in seven or eight minutes.
Strange as it may appear, a ball of a ton weight and another of the same material of an ounce weight, falling from any height will reach the ground at the same time.
The heat does no increase as we rise above the earth nearer the sun, but decreases rapidly until, beyond the regions of the atmosphere, in void, it is estimated that the cold is about seventy degrees below zero. The line of perpetual frost at the equator is 15,000 feet altitude; 13,000 feet between the tropics; and 9,00 to 4,000 between the latitudes of forty degrees and forty-nine degrees.
At a depth of forty-five feet under ground, the temperature of the earth is uniform throughout the year.
In summer time, the season of ripening moves northward at the rate of about ten miles a day.
The human ear is so extremely sensitive that it can hear a sound that lasts only the twenty-four thousandth part of a second. Deaf persons have sometimes conversed together through rods of wood held between their teeth, or held to their throat or breast.
The ordinary pressure of the atmosphere on the surface of the earth is two thousand one hundred and sixty-eight pounds to each square foot, or fifteen pounds to each square inch; equal to thirty perpendicular inches of mercury, or thirty-four and a half feet of water.
Sound travels at the rate of one thousand one hundred and forty-two feet per second--about thirteen miles in a minute. So that if we hear a clap of thunder half a minute after the flash, we may calculate that the discharge of electricity is six and a half miles off.
Lightning can be seen by reflection at the distance of two hundred miles.
The explosive force of closely confined gunpowder is six and a half tons to square inch.