Correspondence — Mr. C. Callaway — Mr. Mc James. 141 



history not less varied and extended than that of tlie entire PalEeozoic 

 era — and which he believes are in all cases of Pre-Cambrian date. 



Dr. Hunt was the principal organizer and first Secretary of the 

 International Committee for a Geological Congress ; the first meeting 

 of which was held at Paris in 1878, and the second at Bologna in 

 1881, at both of which he took an active part as one of the Vice- 

 Presidents, and by his cordiality and good fellowship, backed by 

 ability and knowledge, contributed much to the maintenance of a 

 good understanding among the representatives of all the English- 

 speaking nations gathered at Bologna. His work did not end a*-. 

 Bologna, and on his way home he, first at Paris (Compte-rendu 

 sommaire Soc. Geol. France, Nov. 7, 1881), and afterwards in 

 London (Abst. Proc. Geol. Soc. Nov. 16, 1881), gave an account of 

 his recent examination of the metamorphic rocks of Italy and 

 Germany, and his views as to their correlation with the older 

 crystalline rocks of America and Britain. He also brought before 

 the Philosophical Society of Cambridge his matured views with 

 regard to the distribution of extremely attenuated matter through 

 interstellar space (Proc. Camb. Phil. Soc. Nov. 28, 1881), pointing 

 out that practically the same idea had been suggested by Newton in 

 his earlier work, and had taken more definite shape in later editions. 

 The University of Cambridge conferred on him the Honorary Degree 

 of LL.D., and we hope that this new tie may unite our spirited 

 scientific ally more closely to us, and insure a not too long deferred 

 return to our shore. — Cantab. 



THE TOERIDON SANDSTONE. 



Sir, — I shall be obliged if you will allow me to correct an 

 important misprint which occurs in the abstract of the debate on 

 my paper on the Torridon Sandstone at the Geological Society, 

 Dec. 21st. In my reply, I am represented as saying that north- 

 east of Queenaig the sandstone passes " imconformably " under the 

 quartzite. This contradicts my main conclusion. For "unconform- 

 ably " read " conformably." 



Wellington, Salop, Bee. 31, 1881. C. CallawaT. 



EATE OF DENUDATION OF THE LAND BY EIVEES. 



Sir,— Mr. Tylor seems to have made a slip in his calculations. 

 3^ is not 729 but 243. This makes Mr. Tylor's results three times 

 too much. The 3000 years, of Mr. Tylor's sixth paragraph, will 

 thus become 9000 ; the mean denudation not nine but three inches 

 a year ; and the annual rise of the sea-level one inch only. 



In paragraph five — •' the supposed period of 729 years " is pro- 

 bably a printer's error. 



I am unable to follow Mr. Tylor's reasoning, and shall be glad 

 of some information on the subject. For instance : 



1. Where can I find Mr. Tylor's "formula of the increase of 

 velocity of water at the same slope " ? 



2. Where some account of the " Pluvial Period " ? 



