Correspondence — Mr. F. A. Bather — Rev. Br. Irving. 141 



therms) must move upwards into new deposits as tliey are laid 

 down. This is duly acknowledged in chap. vii. and credited to 

 Babbage, who, I believe, has priority; but should the use of a natural 

 law in building up a theory disentitle the theoriser to the full right 

 of property in his own theory ? 



It is said, " What's in a name? " To which I answer, A great deal 

 that is bad when it is vague and misleading and perpetuates errors 

 and misconceptions. T. Mellard Reade. 



Park Corner, Blundellsands, Fel>. 9tk, 1891. 



CRINOIDAL STEMS IN OEDOVICIAN OF SWEDEN. 

 Sir, — I am glad to have elicited from Dr. Holm such intei'esting 

 information about the crinoid stems that he has found in the Leptasna- 

 kalk of the Lissberg. But I am sorry that my remark has given 

 rise, perhaps not unnaturally, to some misunderstanding. Dr. Holm 

 in his original notice says two things: — First, that the rock is 

 "chiefly composed of corals, cystids, and crinoid stems ;" secondly, 

 that he himself has found there " crinoid stems belonging to at least 

 two species." Now I never doubted that so experienced a palteon- 

 tologist as Dr. Holm had very good reasons for this latter statement ; 

 his letter shows how sufficient those reasons were. Nor did I " with- 

 out having seen a single one of them," venture to assert that all the 

 stem-fragments belonged to Cystidea. 1 was indeed well aware of 

 the sessile nature of the majority of the Cystidea from this locality. 

 But, remembering as I did how often stems undoubtedly cystidean 

 had been referred to Crinoids, and knowing that not a single Crinoid 

 had been recorded from the Ordovician. of Sweden, though 23 species 

 of Cystidea showed the possibility of their preservation, I merely 

 wished, as indeed I still wish, to suggest that some of these ossicles 

 might have pertained to the long and exceedingly crinoid-like stem 

 of Caryocrimis. So inevitable did this seem that, though I did not so 

 far forget either myself or Dr. Holm's very valuable works as to call 

 .him a mere collector, still I did express myself in a manner which 

 now seems to me to need an apology, and this I trust, Sir, you will 

 here permit me to offer. F. A. Bather. 



5 Feb. 1891. 



MOTION OF LAND-ICE. 



Sir, — As I have paid some attention to Glaciers,^ I should like to 

 make a few remarks on the paper by Mr. Goodchild on " The Motion 

 of Land-ice " in the Geol. Mag. for January last, pp. 19-22. 



1. The expansion and contraction of ice for changes of temperature 

 below 0° C. and under a pressure of one atmosphere is but an example 

 of the general law for solids, which has been recognized for many 

 years in physical science ; and the power of ice to resist tensile 

 strain is (as Helmholtz has pointed out) so small as to furnish an 

 explanation of the formation of crevasses, though these are not by 

 any means always produced by contraction due to lowering of 

 temperature. But this very property of ice shows that contraction 



^ Q.J.G.S. vol. xxxix. pp. 62-71, " Oa the Mechanics of Glaciers"; also 

 'Nature,' vol. xxvii, pp. 553, 554, " On Solar Eadiation and Glacier-motion." 



