DESCRIPTION OF PLATES. 



PLATE II. 



Fig. 15. The ball A, revolving round the point B, and being drawn towards it 

 by means of the thread B C, with a force variable at pleasure, its velocity may be 

 observed to vary according to its distance from the point B. P. 29. 



Fig. 16. The curve A B C D E is an ellipsis ; F and G are its foci, A D its greater 

 axis, and C E its lesser axis. P. 29. 



Fig. 17. The horizontal range, A B, of a body projected at an elevation of 45, 

 is greater than A C or A D, the ranges of bodies projected with the same velocity at 

 a greater or less elevation. If the parallel lines E F, G H, be always as the squares 

 of A E, A G, the curve A F H will be a parabola ; and such is the path of a pro- 

 jectile. P. 31. 



Fig. 18. The path of a ball moving swiftly through the atmosphere nearly resem- 

 bles the curve A B. P. 31. 



Fig. 19. The ball A, having descended along the groove A B, describes the para- 

 bola B C, passing through the rings D, E. P. 31. 



Fig. 20. The cylinder A, loaded at the axis, descends along an inclined plane 

 more rapidly than the cylinder B, loaded with an equal weight at the circumference. 

 P. 33. 



Fig. 21. The balls A, B, C, descend along the planes A D, B E, C F, of equal 

 height, in times proportional to their lengths. The upper surfaces of the slips A D, 

 B E, C F, are slightly grooved. P. 33. 



Fig. 22. The balls A, B, C, descend in equal times along the chords A D, B D, 

 CD. P. 33. 



Fig. 23. The same ball, descending from equal heights, at A, B, or C, by differ- 

 ent paths, will rise to the same height at D on the opposite side of E. P. 34. ,'. 



Fig. 24. The thread A B, playing between the cycloidal cheeks A C, A D, de- 

 scribes the cycloid C E D ; and the balls B, F, descending from any two points of the 

 curve, will meet at E, in the same time that the ball G falls from a point nearly of 

 A E above A. The space described by the pendulum in descending is always pro- 

 portional to the height HI, to which a body setting out from E, and revolving 

 uniformly in a circle, will rise in the same time. The circle E I lies without the 

 cycloid C E D, and is somewhat less inclined to the horizon at equal distances from 

 E. P. 35. 



Fig. 25. The ball A, descending from B in the curve B A, arrives at C before the 

 ball D, moving in a right line on the plane B C. P. 36. 



Fig. 26. The balls A, B, C, being made to revolve by means of the whirling table, 

 they are always found in the same horizontal plane. The joint connecting them with 

 the axis is represented at D, as seen from above. P. 36. 



Fig. 27. The equal vibrations, represented by A B, C D, compose, when united, 

 the circular revolution, A E B : the unequal vibrations A B, F G, compose the ellipsis 

 A H B ; the place of the body being always ascertained by combining the versed sines 

 of two circular arcs increasing uniformly. P. 37. 



Fig. 28. The balls A, B, as" their revolution becomes more rapid, fly out, and the 

 point C is depressed. P. 37. 



Fig. 29. The mass of the body A being 1, and that of B 2, and A C being twice 

 B C, C is the centre of inertia [gravity]. P. 40. 



Fig. 30. The balls A and B are suspended by long threads, which allow them to 

 move in the arcs AC, B D ; the ball A is perforated in a horizontal direction, and 

 contains a spiral spring, which is confined by the thread E, and being set at liberty 

 by burning this thread, strikes the ball B, so as to cause each of the balls to move 

 through an arc, of which the chord is proportional to the weight of the other ball. 

 P. 40. 



