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II. On the Mean Height of the Surface-Elevations, and other 

 Quantitative Results of the Contraction of a Solid Globe 

 through Cooling ; regard being paid to the existence of a level of 

 no strain, as lately announced by Mr. T. Mellard Reade and 

 by Mr. C. Davison. By Rev. 0. Fishee, M.A., F.G.S* 



IN an article "which was published in the ' Philosophical 

 Magazine ' for February last, I calculated the mean 

 height of the elevations which might have been formed by 

 the cooling of a solid earth upon the " too highly favourable " 

 hypothesis that the whole cubical contraction of the crust was 

 thrown into the vertical dimension, and that each elementary 

 shell consequently retained its original horizontal extension, 

 which, rendering it too large to fit its new position due to the 

 contraction of the matter interior to it, caused the compression 

 by which that particular shell contributed its share towards 

 the surface-elevations. Upon summing these, the resulting 

 mean value appeared to be too small to account for the 

 existing elevations having been caused by contraction of 

 the crust through cooling merely. 



Mr. T. Mellard Reade had, however, already pointed out 

 what was the truer conception of a cooling globe ; but at the 

 time I had not read his bookf . Afterwards Mr. 0. Davison 

 independently, as I happen to know, arrived at the same 

 conclusion with Mr. Reade ; and in the paper in which 

 he communicated it to the Royal Society in April of this 

 year he criticised my February article as " losing its force," 

 in consequence of the hypothesis not according with the more 

 true conception. In the ' Philosophical Magazine ' for No- 

 vember I think I have made it clear that, inasmuch as I had 

 based an argument upon the effects of contraction being too 

 small according to a certain hypothesis, my argument could 

 not, as Mr. Davison supposed, " lose its force " in consequence 

 of his having offered a better and truer hypothesis, which 

 led to the conclusion that mine did not make the effects of 

 contraction small enough. 



In the same article 1 promised a calculation of the mean 

 height of the elevations, which could be formed upon the new 

 and better hypothesis. This I now send, suggesting that, 

 before reading it, it would be well . to refer to the unmathe- 

 matical article of November. 



We now follow the new hypothesis, that the earth has 



* Communicated by the Author. 



t The Origin of Mountain Ranges (London : Taylor and Francis, 1886), 

 Chap. XI. 



