226 SIR HENEY H. HOWOETH^ D.C.L., F.R.S._, ON ICE OE WATER. 



meiit, and I had to fall back on the theory of the vis a tergo 

 arising from the enormous accumulation of snow over the area 

 of the central axis of dispersion, supplemented by Tyndall's 

 views of the molecular movement arising from the diurnal 

 melting and re-gelation of the ice in the Ijody of the glacier 

 itself. I should add that the flanks and summit of Bray 

 Head are strewn with boulders of limestone, granite and other 

 rocks foreign to this neighbourhood, the sources of which 

 can be determined in several localities over the Central Plain. 



With these examples I conclude my essay and criticism. 

 There are many points on which I agree with the author ; as, 

 for example, the estimate of al30ut 10,000 years (or less) for 

 the glacial period advocated by Gilbert, Upham and Prestwich ; 

 but I fail to find that he has grasped the full significance of the 

 phenomena presented by the Post-Tertiary Ice Age, or that he 

 has recognised the changes of level which the crust has under- 

 gone during that period, or the eftects resulting Irom these 

 changes. 



On reading over this paper again alter the interval since it 

 was written, I am sensible that it is far from being a sufficiently 

 comprehensive review of the work of Sir Henry Howorth. 

 Even the points dealt with w^ould, with advantage, hiive 

 merited a more extended consideration. But I hope it will be 

 admitted that I have endeavoured to meet the questions on 

 which we differ in a fair and courteous manner. For my own 

 part, no one dislikes controversy more than myself. 



Discussion. 



The Chairman. — I am sure we are immensely interested in this 

 review. Although we have not all had time to master the book, 

 of which this is a review, still we have had the pleasure of hearing 

 Professor Hull set forth his deductions of the evidences of the 

 river valleys underneath the sea through the submarine plateaus, 

 and he has most ably proved his points. I now call upon any who 

 have remarks to make to S2)eak to us on this subject. I hope we 

 shall have a very interesting discussion. I regret the absence of 

 ♦Sir Henry Howorth. 



Mr. PiLKlNGTON, M.Inst.C.S., having discussed the subject at 

 some length. 



