78 Scientific Gleanings. 



Owen, for the determination of their generic and specific charac- 

 ters ; but Dr. Falconer seems already to have recognized among 

 . them seven or eight distinct genera, some of them marsupial, and 

 others probably placental, of the insectivorous order. I may also 

 notice, as a matter of great palaeontological interest, the recent 

 discovery of a new Ossiferous Cave, near Brixham, in Devonshire, 

 of which some account is to be brought before us durino this 

 meeting. The past year has been fruitful in palaeontological re- 

 search i. 



The subject of the motion of glaciers is one of interest to 

 geologists, for unless we understand the causes of such motion, 

 it will be impossible for us to assign to former glaciers their proper 

 degree of efficiency in the transport of erratic blocks, and to dis- 

 tinguish between the effects of glacial and of floating ice, and 

 those of powerful currents. An important step has recently been 

 made in this subject by the application of a discovery mnVle by 

 Faraday, a few years ago, that if one lump of ice be laid upon 

 another, the contiguous surfaces being sufficiently smooth to insure 

 perfect contact, the two pieces in a short time will become firmly 

 /the temperature of the atmosphere in which they are placed be 

 many degrees above the freezing temperature. Dr. Tyndall has 

 the merit of applying this fact to the explanation of certain glacial 

 phenomena. There are two recognized ways in which the motiou 

 of a glacier takes place : one by the sliding of the whole glacial 

 mass ever the bed of the valley in which it exists ; and the other 

 by the whole mass changing its form in consequence of the pres_ 

 sure and tension to which it is subjected. The former mode of 

 progression is that recognized by the sliding theory ; the second 

 is that recognized by what has been termed the viscous theory of 

 Prof. Forbes. The viscous theory appeared to be generally recog- 

 nized. Still, to many persons it seemed difficult to reconcile the 

 property of viscosity with the fragility and apparent inflexibility 

 and inextensibility of ice itself. On the other hand, if this pro- 

 perty of viscosity, or something of the kind, were denied, how 

 could we account for the fact of the different fragments, into 

 which a glacier is frequently broken, becoming again united into 

 one continuous mass ? Dr. Tyndall has, I conceive, solved the 

 difficulty. Glacial ice, unlike a viscous mass, will bear very little 

 extension. It breaks and cracks suddenly ; but the separate pieces 

 when subsequently squeezed together again become by regelation 

 (as it is termed) one continuous mass. After some general re- 



