138 TEAR-BOOK OP FACTS. 



of water. Four such ice caverns are found in Switzerland and the 

 neighbouring portion of France ; one being near Besancon. The 

 bottom of the latter cave is covered with ice about a hundred feet 

 square and about a foot thick. There is but one opening to the 

 cave, and so no chance for the circulation of air. The water trickles 

 from the roof or flows in at the mouth, and the cold air which settles 

 in the cave, and freezes all its moisture, maintains its place through 

 the summer by reason of its greater specific gravity, so that the ice 

 wastes very slowly even in the hottest weather. Professor Loomis 

 gave a list of eight such " ice-houses" in different parts of Europe. 

 Similar cases exist in America. On the western bank of Lake 

 Champlain, near the village of Port Henry, is an ice mine which has 

 been extensively worked for many years. There are fifteen such 

 places in the United .States. The phenomenon of frozen wells is ex- 

 plained in the same way ; but to secure a frozen well, it is necessary 

 that the water should not be changed. It is only the fact that the 

 water in most wells is constantly changing, that prevents all of 

 them from presenting this phenomenon. Professor Loomis pro- 

 duced a list of about thirty frozen wells, the most remarkable of 

 which are, one in Tioga, New York, 77 feet deep ; one in Ware, 

 Massachusetts, 38 feet deep; one in Brandon, Vermont, 34 feet 

 deep ; six in Oswego, New York, from 16 to 30 feet ; and one in 

 Prattsburg, New York, 25 feet. 



TRANSMISSION OF RADIANT HEAT THROUGH GASEOUS BODIES. 



Professor Tyndall, in a note communicated to the Boyal 

 Society, states that he has experimented with several Gases and 

 Vapours, and has, in all cases, obtained abundant proof of calorific 

 absorption. Gases vary considerably in their absorptive power — 

 probably as much as liquids and solids. Some of them allow the 

 beat to pass through them with comparative facility, while 

 other gases bear the same relation to the latter that alum does to 

 other diathcrinanous bodies. 



Different gases are thus shown to intercept radiant heat in dif- 

 ferent degres. Dr. Tyndall has made other experiments, which 

 prove that the self-same gas exercises a different action upon 

 different qualities of radiant heat. — (See the paper by Professor 

 Tyndall, in Year- Book vf Facts, lSuO, p. 139.) 



CONDUCTION OF HEAT BY GAS1N. 



Professor ]\I.u. xrs, in a paper on this subject, observes: — The 

 simplest mode of ascertaining whether a gas conducts heat, consists 

 in warming it from above, and observing the action of a thermometer 



placed within. It might lie objected to this method, that even with 



beating from above, currents in the u'as migbtbe formed, and that 

 thereby the temperature indicated by the thermometer in various 

 gases might be different without any difference in oonductibility. 



There is one method of t^ttWg this objection, lor if. in f;ut, a 

 gas can conduct heat, the temperature assumed by :- thermometer in 

 a space heated from above must be lower when the conducting sub- 



