I 10

Sir I s a a c Newton’s Book I.

earth bears so vast a proportion to the greatest length, to whichwe can throw bodies, that this obliquity does not merit anyregard. From the sequel of this discourse it may indeed becollected, what line the body being thrown thus would befound to describe, allowance being made for this obliquity ofthe earth’s action \ This is the discovery os Sir Is. Newton;but has no use in this place. Here it is abundantly sufficientto consider the body as moving in a parabola.

90 . The line, which a projected body describes, beingthus known, practical methods have been deduced fromhence for directing the shot of great guns to strike any ob-ject desired. This work was first attempted by Galileo,and soon aster farther improved by his scholar Torricelli;but has lately been rendred more complete by the greatMr. Cotes, whose immature death is an unspeakable loss tomathematical learning. If it be required to throw a bodyfrom the point A (in fig. yo. ) so as to strike the point B ;through the points A, B draw the straight line C D, and erectthe line AE perpendicular to the horizon, and cs sour timesthe height, from which a body must fall to acquire the velo-city, wherewith the body is intended to be thrown. T hroughthe points A and E describe a circle, that shall touch the lineC D in die point A. Then from the point B draw the lineB F perpendicular to the horizon, intersecting the circle in thepoints G and H. This being done, if the body be projecteddirectly towards either of these points G or H, it shall fall up-on the point B; but with this difference, that, is it be thrown

- From B II. Ch. 3. 111