324 POPULAR LECTURES AND ADDRESSES. 



" by means of the transference of the polar ice from 

 " one hemisphere to the other." 



I wish you to notice particularly the last sen- 

 tence of that note, for it is to that my attention 

 has been called by your secretary. I was quite 

 unaware that by this statement I had placed 

 myself under any obligation, but it so turns out. 

 A friend suggests that the quotation marks as 

 supplied to that last sentence be here deleted, 

 and the passage given as Mr. Croll's own. Mr. 

 Croll may well have adopted it, for after quoting 

 my note he at once proceeds to carry out the 

 intention which I expressed in the concluding 

 sentence. For myself I can only say that I am 

 now trying to fulfil my obligation, though I feel I 

 can throw but little additional light on the sub 

 ject. Nor do I need to do so : it is quite un- 

 necessary for me to carry out the intention, since 

 Mr. Croll has done it with all the means that 

 occurred to him as bearing on former estimates, in 

 regard to this very important and difficult subject. 



With regard to the effect on sea-level Mr. ('roll's 

 principle, as set forth in pp. 368-369 of his book, is 



