THE TIDAL WAVE ON THE OFF SIDE OF THE EARTH. 179 



complex and difficult; and that the well-known figure of 

 high water under the moon, where the moon drags the water 

 away from the earth, and another high water on the opposite 

 side where the moon drags the earth away from the water, is 

 responsible for not a little misconception." I entirely agree. 



The last work to which I shall refer is by Sir George 

 H. Darwin on The Tides* I had hoped that I should have 

 here a clear and intelligible theory of the origin of the second 

 tidal wave on the side opposite from the moon, but in this I 

 have been disappointed. The cause of this may, I admit, lie 

 with myself, but from the statement made on this subject by 

 Mr. A. R. Hinks — who cannot have been ignorant of Darwin's 

 investigations — I gather that he also was unable to accept his 

 reasoning, otherwise he would have quoted him with approval. 

 Darwin's reasoning is certainly obscure, and I venture to say 

 incorrect, as he makes the moon's attraction to act in opposite 

 directions on opposite sides of the earth at the same time. 

 This I cannot admit.f Further references are unnecessary ; 

 and as there seems to be no generally recognized explanation 

 available, this is my apology for offering one. Before proceed- 

 ing further, I may here state explicitly that I do not consider 

 the direct attraction of the moon to have any appreciable 

 influence on the formation of the antipodal tide wave. This 

 will appear in the sequel. 



Proposed Solution of the Problem. — Let us take the simplest 

 •of possible representations of our globe — an orange. This 

 fruit consists of an enclosing rind formed of a solid but flexible 

 material resting on a semi-fluid interior. Squeeze the orange 

 between the finger and thumb, with the result that the fruit 

 will bulge outward at both the intermediate sides between the 

 points of pressure. To compare small things with great is a 

 favourite expression, and may be used in the present case if it 

 can be shown that the lateral pressure on the orange has its 

 counterpart in the lateral pressure exercised by the moon 

 in the case of the globe, of which we must now consider the 

 structure. 



T/ie Structure of the Globe. — The globe consists of a solid, but 

 flexible, envelope called " the crust," of variable and unknown 



* Third edition (1911). The substance of lectures delivered in 1897, 

 at the Lowell Institute, Boston. 



t The reader is referred to chapter 5, p. 94, on " The tide generating 

 force," and figs. 22 and 23, pp. 103 and 108. Darwin's views are repeated 

 in the Encyclopedia Britannica, 11th edition, article "Tides," with great 

 elaboration. 



N 2 



