2 72 THE POPULAR SCIENCE MONTHLY. 



effect, drawn away from the waters on the far side of her, and thus, 

 the water being left behind, a tide is produced on this side, as well as 

 on the side at which the force of gravity acts directly. That so great 

 an absurdity could have been accepted so long by our writers of text- 

 books, is truly marvelous. It is, indeed, so contrary to all known 

 facts and laws of physics that, if no other influence were felt by the 

 waters at the far side of the earth than attraction, there would be 

 just the opposite effect produced to that alleged by this absurd 

 hypothesis. This can be demonstrated by actual experiment, and as 

 conclusively as any other fact coming within the reach of experimen- 

 tal philosophy. It has been proved experimentally that all bodies ou 

 the surface of the earth at midnight are heavier than at any other 

 hour of the twenty-four; and that when new moon occurs at midnight, 

 this increase of weight or gravity felt by matter on this part of the 

 surface of the earth is still greater. Now, if this theory were correct, 

 attraction would produce just the opposite effect; that is, matter 

 would weigh less at midnight than at other hours of the twenty-four. 

 On the side of the earth facing the sun and moon, the weight of bodies 

 is diminished, as it should be, according to the theory which I propose 

 to establish in this article. 



The truth of this fact is very easily accounted for. Suppose the 

 earth were placed in such a position, in space, that she could not 

 feel any of the sun's attraction, nor that of any other body. Then 

 gravity would be equal on all parts of the earth's surface, on the sup- 

 position of its being a perfect sphere and at rest. But now bring her 

 within the attractive influence of the sun. Then all particles of mat- 

 ter on the earth's surface most remote from the sun would feel the 

 force of gravity of both the sun and the earth ; and these two forces 

 would act in the same direction and in the same straight line, directed 

 through the centre of the earth to the centre of the sun. On the side 

 facing the sun, these two forces would also act in the same straight 

 line, but in opposite directions. Hence a decrease of Aveight on one 

 side and an increase thereof on the opposite side of the earth. The 

 same result follows between the earth and moon under a similar suppo- 

 sition. It is therefore not true that the least amount of attraction is 

 felt by the waters of the earth at that part of her surface most remote 

 from the sun or from the moon. It is indeed true that the sun and 

 moon have less power of attraction on the particles of matter at this 

 pai't of the earth's surface than they have on particles of matter facing 

 them. But, as attraction diminishes as the square of the distance in- 

 creases, this attractive force of these two bodies on any part of the 

 earth's surface is not near so great as that of the earth herself on such 

 part of her surface. Therefore, as these remote particles feel the 

 attraction of sun and moon plus the attraction of the earth herself, 

 they are drawn with greater force toward the centre of the earth than 

 any other particles. Consequently, it cannot be true that the whole 



