﻿40 Correspondence — Prof. A. JS. Green. 



of these objects radiating their heat more rapidly than the sur- 

 rounding air, and because they are solid forms presented to a liquid 

 at the moment of crystallization, the feathers of the hoar frost ex- 

 tending to windward as each particle of water is driven by the breeze 

 and frozen upon it. 



So in a stream of water at the freezing-point, the stones at the 

 bottom no doubt radiate their heat more rapidly than the surround- 

 ing medium, and particle after particle of water assumes its crystalline 

 form on coming in contact with the solid, thus forming tubular 

 masses in the direction of the stream. 



124, WiNCHEAP, Canterbury. S. GordoN McDakin. 



PROF. NORDEXSKIOLD ON EECUREENT GLACIAL PERIODS. 



Sir, — Prof. Judd has told us repeatedly of late, not without some 

 flourish of trumpets, how completely Prof. Nordenskiold has de- 

 molished Mr. Croll and his theory of the causes of glacial epochs. 

 Now from my youth up 1 have been backward in my reading, and 

 have had an unconquerable aversion to books, and never read any- 

 thing myself, if I can get a kind friend to read it for me, and tell 

 me what it is about. So I have not yet read Prof Nordenskiold ; ^ 

 Prof Judd is evidently thoroughly well up in him, and he would be 

 doing a great kindness to myself, and perhaps others who are equally 

 ignorant and lazy, if he would send you a short article giving Prof. 

 Nordenskiold's facts and arguments. Prof. Judd says these do not 

 support Mr. Croll's theories ; but what I especially want to know is, 

 whether there is anything in them that tells against the generally 

 received views on the subject. 



Yorkshire College of Science, Leeds. A. H. Green. 



Dec. 9th, 1876. 



GLACIAL ORIGIN OF LAKES. 



Sib, — I have to ask for space for a reply to the courteous letters of 

 Mr. Bonney and of my friend Mr. Judd. 



Mr. Bonney's letter is mainly explanatory of his position, which 

 several circumstances — unnecessary to detail — combined to render 

 somewhat ambiguous. I think comparison would tend to show that 



1 The paper by Prof. Nordenskiold especially referred to by Prof. Judd, is " On 

 the Former Climate of the Polar Regions," being an address by Prof. Nordenskiold 

 delivered at the Anniversary Meeting of the Royal Swedish Academy of Sciences, 

 March 31, 1875, and translated and printed in full in the Geological Magazine, 

 1875, Dec. IT. Vol. 11. p. 525. The passage quoted by Prof. Judd appears at p. 531, 

 but the whole paper is well worthy of perusal ; as is also his paper " On the Geology 

 of Icefiord and Bell Sound, Spitzbergen," Geological Magazine for 1876, pp. 16, 

 63, 118, 255. Perhaps Prof. Green will "get a kind friend to read them for him." 

 Nordenskiold's " Expedition to Greenland" also appeared in the Geol. Mag., 1872, 

 Yol. IX. pp. 289, 355, 409, 449, 516, and has some good materials in it bearing on 

 the former climate and the extinct floras. Many of our readers, when oppressed with 

 the wearisome effort to master the contents of our monthly issue, will cordially sympa- 

 thize with Prof. Green, and wish for a mental digester and Assimilator (like the 

 Artificial Stomach in the Loan Collection) into which, as into a "Papin's Digester," 

 they might put their heavy reading, and so get therefrom the extractum aeusorum in 

 a concentrated form. Till this invention is patented. Prof. Green has hit upon a 

 happy expedient: " Get a kind friend to tell you what it is about" ! — Edit. Geol. Mag. 



