tlon to her orbit and its centre, no part of her circumference pass- 

 ing the one or crossing the other during the whole revolution, 

 so as to shew the indispensable signs of rotation, or whirling 

 round on an axis. And to make the matter worse, it is alleged 

 that every " vicissitude of succession" in the parts of the moon's 

 circumference, with respect to the earth, might be produced 

 loithout rotation^ thereby completely confounding and running 

 counter to the great lexicographer's definition, as well as to com- 

 mon sense. By " rotation," or turning round on an axis, is 

 universally understood to be meant the fact of a body's moving 

 all the parts of its circumference round about an axis within it- 

 self, presenting them all in succession on every side of that axis, 

 and making them all in their turn pass a straight line, real or ima- 

 ginary, connecting that axis with a given point outside, perpendicu- 

 lar to the body's line of motion ; or, in other words, crossing the 

 line of motion at right angles; such as, in the moon's case, the ra- 

 dius-vector that connects her axis with the centre of her orbit, and 

 which, if her orbit were a perfect circle, would be always perpendi- 

 cular to her line of motion, and cross her orbit at right angles, at 

 whatever point of that orbit the moon might be for the time ; or, 

 as in the case of a common wheel, a rod crossing it diametrically, 

 perpendicular to the road or rail along which it is moving, or a 

 wheel moving in a frame with which its axis is connected by a 

 cross bar. But, when the moon rotates^ as is maintained, so 

 far is she from moving all the parts of her circumference round 

 about her axis, presenting them all in turn on every side of that 

 axis, and making them in succession pass her radius-vector or 

 cross-bar, that, on the contrary, she keeps them all invariably 

 on the same side of her axis, and the same three points of her cir- 

 cumference severally attached to the radius- vector, and to the orbit 

 at either side, 90° from that radius ; while the inner end of the 

 radius-vector is virtually attached to a fixed point which never 

 changes its place, so far at least as the moon is concerned. If 

 the radius were loose, so as to be at liberty to move past the or- 

 bit's centre, it might be considered as virtually a portion of the 

 moon's substance, and consequently as partaking of all the moon's 

 movements; and, in that case, there might be some show, but only 

 a show, of truth in the allegation. But when it is considered that 

 the radius is, on the contrary, virtually a part of the centre of the 

 orbit itself, merely an extension or expansion of that centre, and 

 nothing more than the representative of the several points of its 

 circumference in succession at the place where the moon passes 

 them, even the show of truth is gone, and the doctrine stands forth 

 in its glaring absurdity. Moreover, astronomers affirm, that if 

 the moon were to move the parts of her circumference backwards, 

 or from east to west, across the orbit outwards in that direction, 



