VOL. XLI.J PHILOSOPHICAL TRANSACTIONS. 323 



what difference would arise, if the clocks were fixed on a more solid floor, he 

 placed them, exactly in the same manner as in the last experiment, on the stone 

 pavement under the piazzas of the Royal Exchange, and stuck the piece of 

 wood between them, as before ; and setting N" ) a going, the only difference 

 was, that it was 1 5 minutes before N° 2 was set a going, and N° 1 continued 

 going near half an hour before it stopped. 



From these experiments Mr. E. thinks it plainly appears, that the pendulum 

 which is put in motion, as it moves towards either side of the case, makes the 

 pressure on the feet of the case to be unequal, and, by its weight, occasions a 

 small bearing or motion in the case on that side towards which the pendulum is 

 moving; and which, by the interposition of any solid body, will be communi- 

 cated to the other clock, whose pendulum was left at rest. The only objection 

 to this, he conceives, is the different effects which the two pendulums seemed 

 to have on each other. But this he hopes to explain to satisfaction. -^ 



For, notwithstanding these different effects, he soon found, by several 

 experiments, that the two clocks mutually affected each other, and in the same 

 manner, though not with equal force ; and that the varieties observed in their 

 actions on each other, arose from the unequal lengths of their pendulums 

 only. 



For, on moving one of the clocks to another part of the room, and setting 

 them both a going, he found that N° 2 gained of N° 1, about l™ 36* in 24 

 hours. Then fixing both against the rail, as at first, he set them a going, and 

 made the pendulums to vibrate about 4° ; but he soon observed that of N" 1 to 

 increase, and that of N° 2 to decrease ; and in a short time it did not describe 

 an arch large enough to keep the wheels in motion. In a little time after it 

 began to increase again, and in a few minutes it described an arch of 2°, and 

 the clock went. Its vibrations continued to increase for a considerable time, 

 but it never vibrated 4°, as when first set a going. While the vibrations of 

 N° 2 increased, those of N° 1 decreased, till the clock stopped, and the pen- 

 dulum did not describe an arch of more than 1° 30'. It then began to increase 

 again, and N" 2 decreased, and stopped a second time, but was set a going 

 again, as before. After this N° 1 stopped a second time, and the vibrations 

 continued to decrease till the pendulum was almost at rest. It afterwards in- 

 creased a small matter, but not sufficiently to set the work a going. But N*^ 2 

 continued going, its pendulum describing an arch of about 3". 



Finding them to act thus mutually and alternately on each other, Mr. E. set 

 them both a going a second time, and made the pendulums describe as large 

 arches as the cases would permit. During this experiment, as in the former, he 

 sometimes found the one, and at other times the contrary pendulum to make 



T T 2 



