440 The Phcenojnena of Gravitation proved to he proximate 



ILLUSTRATION. 

 3) C 



If a ball be projected from A perpendicularly towards D, and 

 A be supposed to be on the deck of a ship, which is moving at 

 any given rate, from the part A towards the part B ; then the 

 ball, instead of ascending to the point of space at D, will, with- 

 out material error, move in the diagonal AC, by the compound 

 forces which, in the same time, would have carried it to D or F ; 

 and in descending it will fall to the deck at B, to which the 

 point A, in the interim, has advanced. It has in truth performed, 

 instead of an apparent perpendicular, the two sides of the tri- 

 angle, or the curve ACB ; and instead of falling at the point of 

 space A, whence it was projected, it has advanced with the ship, 

 and fallen at the point of space B, to which A has advanced; 

 and in falling has respected the ship, and not the point of space, 

 or the earth at A. It was not however attracted by the ship, 

 but merely impelled in the diagonal by the motion of the ship, 

 in which it previously participated. 



These cases fully illustrate the principle for which I contend ; 

 but, of course, the relations and powers of the ship, and man 

 moving on the moving earth, are included within the more ex- 

 tensive relations and powers operating in Nature, in the pro- 

 digious forces generated by the annual and diurnal motions of 

 our planet. The case of a body thrown upward from a ship in 

 motion, merely shows that, in falling, it obeys a law growing out 

 of the motion of the ship ; in like manner as bodies projected 

 from the earth, or falling tow^ards it, obey a similar law of motion 

 growing out of similar motions of the earth. The law in both 

 cases is a mere result of the composition of motion, and not an 

 effect of any occult or mysterious power. 



These examples, and others that might be adduced, serve, 

 however, to prove the exact analogy of the powers, the ph;eno- 

 inena, and the results. No experiments in physical philosophy 

 seem to afford more conclusive analogical proofs of doctrines re- 

 lative to any natural operations, which are too vast to be viewed 

 by man on their great scale. 



The recognition oi" the principles of this paper may be ex- 

 pected to lead to more precision in the doctrines of projectiles. 

 Many incomprehensible irregularities in Dr. Hutton's and Mr. 

 Robins's experiments on gunnery may be found to arise from the 

 contrariety, opposition, or neutrality, of the direction of the ro- 

 tary 



