NOMOS. 143 



when the sun and moon are on opposite sides of the 

 earth. They show, indeed, that the influence of the 

 sun is similar to that of the moon, only far feebler 

 in degree. It is, indeed, very difficult to look at 

 these diagrams, and suppose that these tides are 

 caused by the attraction of the sun and moon. This 

 is obvious ; but it is not so obvious what Another 

 other conclusion is to be drawn from 

 them. After what has been said, how- 

 ever, the question naturally arises whe- b J ections - 

 ther the moon may not act upon the earth J^^fJ 

 in the same manner as the sun, and cause mediately 



. . -IT. under the 



a bulging out in the region underlying 

 the moon, and in the region diametrically 

 opposed to this ; and whether the tides 

 are caused, not by a change of level in the rise out of 



J & the water in 



water, but by a change of level in the obedience to 



11 mi j i A i l the ex ?an- 



land. This is the question which na- sive action of 

 turally arises under the circumstances. water ^ain- 

 Now it is obvious that such a theory mgitsievei. 

 will not have to contend against the three difficulties 

 which have just been considered. In the first place, 

 it is quite intelligible that the tides should be high 

 on the coasts of great continents, and wanting, or 

 but very feeble, in mid-ocean; for if the land expands 

 in proportion to the extent of surface exposed to 

 the heat, then it may be supposed that the alter- 

 nate expansions and shrinkings of a continent will 

 be greater than those of an island, and that, conse- 

 quently, the tides will be greater around a continent 

 than around an island. In the second place, it is 

 equally intelligible that, instead of following the 



