Comparative Value of different kinds of Parrot Coal, §fc, 228 



lower part, of the oval glacier^ for which I have taken that of 

 the Rhone as a type ; whilst many of the tributary glaciers of 

 Grindelwald and the Jungfrau bear ample testimony to the 

 general fact, that the structure of glaciers is developed during 

 their progression, and after their primitive stratification has 

 been annihilated, by their being projected in avalanches over 

 appalling precipices. 



To these brief notes, I have only to add one interesting dis^ 

 covery, though of a somewhat local importance, which I made 

 at Chamouni. The ancient lateral moraine of the Glacier des 

 Bois is acknowledged by De Saussure, and all subsequent 

 writers, to be found in the barrier of debris which crosses the 

 valley of Chamouni, at Les Tines ; but very feeble traces have 

 (I believe) been observed of -the corresponding lateral moraine 

 of the left bank of the glacier, excepting those J^etween the 

 Chalet of Montanvert, and the descent of La Filia. I have 

 ascertained, however, that a good part of the ascent to the 

 Montanvert, and especially near the chalets of Planaz, passes 

 over a vast accumulation of debris, whose nature corresponds 

 to that of the granites of the central chain, and which lies to 

 an immense thickness against the rocky slopes of the valley, 

 at the foot of the Aiguille de Blaitiere. The resistance offered 

 by this mass of debris to the progress of the torrents, which 

 descend from the glaciers of Grepau and Blaitiere towards 

 the Arve, has diverted their course in a direction parallel to 

 that of the valley of Chamouni, and it was the observation of 

 this singularity which led me to the detection of the moraine 

 first-mentioned, which I could hardly believe had escaped me 

 so long. 



On the Comparative Value of different kinds of Parrot Coal, or 

 Candle Coal, for yielding Gas, and on the Illuminating 

 Pofvers of Gas at Different Distances frotn the Manufactory, 

 By Andrew Fyfe, M.D., F.R.S.E., F.R.S.S.A. (Commu- 

 nicated by the Royal Scottish Society of Arts.)* 



Having for some time past been extensively engaged in con- 

 ducting experiments with the view of ascertaining the illumi- 

 nating power of gas from different kinds of parrot coal, and, 



* Read before the Society, 8th Janiiary 1844. 



