1811.] On the Antilunar Tide. 207 



increasing distance ; for all this follows, of necessity, from the 

 general law. But this does not appear to be the effect inferred hy 

 M. M*Laurin, in the passage first above qvioted. Indeed it is ma- 

 nifest that such a position could have been of no use to his theory 

 of the moon's orbit and the antilunar tide. For tirese principlet 

 depend for their effects on absolute separation and increased dist- 

 ance. What then is the Newtonian principle ? It can he nothings 

 short of this, Tliat an endeavour or tendency to separate two bodies, 

 is equal to an uclual separation, and equally diminishes their mi'.tual 

 gravities. Therefore, that an endeavour to separate the earth and 

 moon, or the inferior surface of the earth, from the incumbent 

 waters, will diminish the gravity of the mnon and of the waters. 

 The expression " endeavour to separate" is certainly a vague one. 

 Supposing that the sun may be considered as endeavouring to dra\T 

 the earth towards him, and that his endeavours with respect to the 

 earth and moon in certain situations may not be equally vigorous, 

 it is clear that the separation is not liis object. It would only he a 

 consequence of his action being unequally applied, and wt)uld at 

 best be an insignificant consequence. But whatever the sun's en- 

 deavours might do, if they were successful, certainly they can 

 effect nothint; when thev are unsuccessful. The endeavour to draw 

 both the earth and the moon towards him is completely counter- 

 acted by the centrifugal force ; and therefore as the main circum- 

 stance, of whicii the separation would be merely a consequent, 

 does not happen, it is certain the consequent cannot liappen. 

 There being no separation, the endeavour to separate can produce 

 no effect. 



It will he said indeed that the earth and moon do actually fall 

 to each oth6r and to the sun, because they fall from the tangents 

 of their curves. This however is a fallacy. If one of these 

 bodies fell from the tangent, and the otiier did not, then, as there 

 would be an actual separation, tiicre would be a diminution of gra- 

 vity, though not such a diminution as v/ould support the disputed 

 theory. But as the two sides of the earth and the moon do ail fall 

 from the tangents of tlieir orbits ; and do not, in fact, fall away 

 from each other, their relative situritier's and gravities remain un- 

 altered. But there is another fact in the relative situation of these 

 bodies, equally conclusive against such effects being produced, by 

 the circumstance of the cartii falling frcrh the tangent of its orbit. 

 The eccentricity of the earth's orbit is so small, that it is always 

 concave to the stm : when the moon is in opposition therefure, the 

 eartli is falling ft om her, and not towards iicr; it being impossible 

 for a body to move in opposite directions at one and the same time, 

 and the earth at that lime, as \i\ all times, falling from a tangent 

 towards the, sun. Wc come then, to tl-.is general result, that 

 even were the earth and moon to fall freely to the sun, no other 

 effect M'ould be piodured oti tiieir gravities, than that produced by 

 the general l.iw, which diminishes their gravities invi rsely as the 

 wjuarc of tlicir intj'i;asjng distances; and that as these bi dies do 



