16 



that a, by turning round on the moon's axis, occupies at the mo- 

 ment at which each quarter point of the orbit reaches the moon, 

 always the very position rehitively to the orbit and the radius- 

 vector that it would occupy, were the orbit to stand still and the 

 moon to revolve, with her face always looking south, which 

 astronomers say, would be the result of revolving in her orbit 

 without turning round on her axis. Just lift the diagram, and 

 turn it round in the proper direction, and this will be seen at 

 once. It is, indeed, perfectly undeniable, and confutes beyond 

 the possibility of redemption the ridiculous blunder that has so 

 long disfigured the most perfect of the sciences. 



To say, therefore, that the moon's presentation of the same 

 point of circumference constantly to the earth, is the consequence 

 of her rotation, implies nothing less absurd than an orbital revo- 

 lution of the earth itself, round about the moon's axis, at the 

 very time the moon is rotating about the relatively fixed earth ! 

 For, if the moon rotate with the same face constantly to the 

 earth, the earth, to keep her in countenance, must inevitably 

 rotate also, and in the same direction, round about the moon's 

 axis, as if she, (the earth,) were only a part of the moon's cir- 

 cumference, or an outlying member attached by an inflexible 

 radius. It might be possible for the two bodies to revolve, like 

 the binary stars, about one common axis situate between them, 

 and such, I believe, is the fact ; but for them to revolve about 

 each other's axis, at one and the same time, is perfectly impos- 

 sible ; yet nothing less than this perfect impossibility is required 

 to support the received doctrine of the moon's rotation. But, 

 perfectly impossible as it is, no less great men than Galileo 

 and Laplace have both jumped at once to this conclusion, 

 as the only discoverable means of getting out of the dilemma 

 occasioned by the parallelism which we have now discussed and 

 accounted for. The perfect impossibility of the earth's and the 

 moon's simultaneous revolutions about each other may be demon- 

 strated by the experimenter's taking a rod or stick, with a ball on 

 each end, and making the two balls revolve about each other, if he 

 can. One of them may be made to revolve round about the other 

 at rest, and both may be made to revolve simultaneously about 

 an axis between them at some intermediate part of the stick ; but 

 to make them revolve simultaneously round each other, he will 

 soon find to be perfectly impossible. Yet, in the face of this 

 utter impossibility, the great Laplace scruples not to say, that a 

 person in the centre of the moon, supposed transparent, and re- 

 volving about the earth without rotating on his, or her, own axis, 

 that is to say, preserving the parallelism we have spoken of, 

 would see the earth and her visual ray revolve about himi that is. 



