ON ICE AS AN AGENT OF GEOLOGIC CHANGE. 171 



Report of the Committee appointed to get cut and prepared Sections 

 of Mountain- Limestone Corals for Photographing. The Committee 

 consists 0/ Henry Woodward^ F.G.S., Dr. Duncan, F.R.S., Pro- 

 fessor Harkness, F.R.S., and James Thomson, F.G.S. (Reporter). 



The operations of this Committee have been carried on indefatigably during 

 the past year ; the results are very promising, but much additional work 

 must be performed before any satisfactory conclusions can be arrived at. 



"VVe have cut several hundred sections, but many of them have been so 

 crushed and fractured, that they are absolutely useless for our purpose ; 

 thus in one lot of eighty-seven we found only two specimens sufficiently per- 

 fect to be of any use ; this is to be regretted, as it is desirable to select as 

 perfect specimens as possible for photographing, and also for the use of Dr. 

 Duncan for describing in the Transactions of the Palseontological Society. 



Those cut, and partly cut, consist of the following genera : — Cyathophyllum, 

 Cyclojjhi/llum, CUsiophyllum, and allied forms, LonsdaVia, Zephrentis, Am- 

 plencu^, Michelinia, i^yringojjora, Lithostrotion and its varieties. 



The time and labour involved in superintending the cutting, examining, 

 and finishing those which are sufficiently perfect, will explain the impossibi- 

 lity of producing this year so complete a set as we could have wished. 

 However, we have been sufficiently successful to warrant us in saying that 

 with those made, and others in readiness to make, we wiU be able to produce 

 in another year a very full set of plates. 



With the plates already finished we have been trying a number of experi- 

 ments in photography ; finding that by the usual process the colour fades by 

 exposure to light, we went to Newcastle and examined Mr. Swan's carbon 

 process ; and, being satisfied that it was an improvement, we left three plates 

 with him, and we now exhibit the results, satisfactory in two of them, while 

 the other has some defects ; we are, however, in hopes that soon we wiU be 

 able to produce fac-similes on zinc or copper plates. Mr. Swan has been 

 trying experiments for that purpose, and he is in hopes of being successfid. 

 If so, we will be able to produce them in any number, and at such a mode- 

 rate price that they will be available for ordinary publishing purposes. If 

 not successful, we expect to be able, by the carbon process, to produce sets 

 of plates which wiU. be placed in a few of the principal Museums when com- 

 pleted. 



Report on Ice as an Agent of Geologic Change. By a Committee, 

 consisting of Professor Otto Torell, Professor Ramsay, LL.D., 

 F.R.S., and H. Bauerman, F.G.S. (Reporter). 



We are of opinion that the work already done in the investigation of the 

 phenomena connected with ice is not sufficient to enable us to prepare a 

 Keport showing the precise effect of " ice as an agent of geologic change ;" 

 but enough has been done to show in part the manner in which the subject 

 may be followed, for the purpose of obtaining information as to the quanti- 

 tative action of glaciers, both as regards their erosive and transporting 

 powers. 



First. We would select a well-known glacier-region, such as the Alps, 

 and there for preliminary investigation fix on a large glacier, simple in 

 structure and easily accessible, such, for example, as the lower glacier of the 



