NOMOS. 139 



and to cause a corresponding wave on the 

 opposite side of the earth by drawing the 

 land beneath the water at that part, and 

 that the moon plays a greater part in this 

 process than the sun, for reasons which factory. 

 will have to be alluded to presently has long been 

 allowed to be insufficient to account for all the phe- 

 nomena. Nor is the amendment of Laplace that 

 the discrepancy between the theory and the facts 

 is mainly owing to the friction of the tidal wave 

 upon the bed of the sea and against the coasts 

 sufficient to meet the exigencies of the case. Indeed, 

 the simple truth is, that the more we know of the 

 tides the more we are dissatisfied with either theory 

 or amendment. 



If the tides be caused in this way, it may be 

 asked, how is it that they are strongest on the coasts 

 of great continents, and feeblest in mid- Onegreat 

 ocean? The usual height of the tides objection to, 



the present 



around the great continents is from ten to theory of the 

 twelve feet; whereas at St. Helena it is 

 not more than three feet, and at the majority of the 

 islands in the centre of the Pacific the tides are 

 scarcely perceptible. Indeed, at a comparatively 

 small distance from land, if this land be a small 

 island, we cease to have any evidence of tides. But 

 this is the very reverse of what is required by 

 theory; for according to theory we should expect 

 the highest tides in mid-ocean, where there is more 

 water to raise and where there are fewer impediments 

 to the free motion of the tidal wave. 



Again, if the tides are caused by a great wave 



