30 POPULAR LECTURES AND ADDRESSES. 



inside the supposed friction-strap. The amount 

 of each of these forces constituting the supposed 

 couple holding back the equatorial friction-strap, 

 would be equal to the weight of two million tons, 

 according to the hypothesis and calculations taken 

 from the Rede Lecture (Cambridge, May, 1866) 

 on the " dissipation of energy," in the abstract 

 appended to the present article. This hypothesis 

 supposes II H' to be inclined to OM, at an angle 

 of 45, the position in which, with a given amount 

 of protuberance, the tidal retardation of the 

 earth's rotation would be a maximum : having 

 been assumed for the purpose of estimating a 

 superior limit to the conceivable amount of the 

 influence in question. The resulting retardation 

 would be the same as if the earth had (as a 

 common "terrestrial globe,") pivots at the North 

 and South poles, each half an inch diameter, and 

 resisting forces were applied tangcntially to these 

 pivots, amounting in all to four thousand million 

 million tons force. With the same supposed 

 degree of protuberance in the luni-tidal spheroid, 1 



1 Tliis is such as would make the average amount of rise of tide 



