Page:Newton's Principia (1846).djvu/359

 theory to describe in 8″ 12‴. But by the experiment it described a space of 220 feet. The difference is insensible.

By like calculations applied to the other globes full of air, I composed the following table.

. 14. Anno 1719, in the month of July, Dr. Desaguliers made some experiments of this kind again, by forming hogs' bladders into spherical orbs; which was done by means of a concave wooden sphere, which the bladders, being wetted well first, were put into. After that being blown full of air, they were obliged to fill up the spherical cavity that contained them; and then, when dry, were taken out. These were let fall from the lantern on the top of the cupola of the same church, namely, from a height of 272 feet; and at the same moment of time there was let fall a leaden globe, whose weight was about 2 pounds troy weight. And in the mean time some persons standing in the upper part of the church where the globes were let fall observed the whole times of falling; and others standing on the ground observed the differences of the times between the fall of the leaden weight and the fall of the bladder. The times were measured by pendulums oscillating to half seconds. And one of those that stood upon the ground had a machine vibrating four times in one second; and another had another machine accurately made with a pendulum vibrating four times in a second also. One of those also who stood at the top of the church had a like machine; and these instruments were so contrived, that their motions could be stopped or renewed at pleasure. Now the leaden globe fell in about four seconds and ¼ of time; and from the addition of this time to the difference of time above spoken of, was collected the whole time in which the bladder was falling. The times which the five bladders spent in falling, after the leaden globe had reached the ground, were, the first time, 14¾″, 12¾″, 14$$\scriptstyle \frac{5}{8}$$″, 17¾″, and 16$$\scriptstyle \frac{7}{8}$$″; and the second time, 14½″, 14¼″, 14″, 19″, and 16¾″. Add to these 4¼″, the time in which the leaden globe was falling, and the whole times in which the five bladders fell were, the first time, 19″, 17″, 18$$\scriptstyle \frac{7}{8}$$″, 22″, and 21$$\scriptstyle \frac{1}{8}$$″; and the second time, 18¾″, 18½″, 18¼″, 23¼″, and 21″. The times observed at the top of the church were, the first time, 19$$\scriptstyle \frac{3}{8}$$″, 17¼″, 18f¾″ 22$$\scriptstyle \frac{1}{8}$$″, and 21$$\scriptstyle \frac{5}{8}$$″; and the second time, 19″, 18$$\scriptstyle \frac{5}{8}$$″, 18$$\scriptstyle \frac{3}{8}$$″, 24″, and 21¼″. But the bladders did not always fall directly down, but sometimes fluttered a little in the air, and waved to and fro, as