364 THE RENEWAL OF ANTARCTIC EXPLORATION. 



ditions.* A party of well-equipped ol)server.s — who siionkl spend a 

 winter on the Antaretic continent— would doubtless bring back valua- 

 ble int'ormation for the discussion of this interesting problem, such as 

 serial temperatures from borings in the ice cap, both \ ertically and hori 

 zontally, the temperature of the eartlfs surface beneath the ne, whether 

 or not water runs away from under the glaciers, as well as observations 

 concerning the appearance of the ni)per surface ot the ice tields and 

 the motion of tne ice over the land. 



Our knowledge of the meteorology of the Antarctic regions is limited 

 to a few observations during tlie summer months in very restricted 

 localities, and is therefore most imperfect. One of the most remarka- 

 ble features in the meteoroU)gy of the globe is the low atmospheric 

 pressure, maintained in all seasons, in the Southern Hemisphere south 

 of latitude 40'^ south, with its inevitable attendant of strong westerly 

 winds, large ram and snow-fall, all round the globe in these latitudes. 

 The observations hitherto made point to the existence over certain parts 

 of these latitudes of a mean pressure of 29'00 inches and under, — as 

 for example to tlie southeast of the Falkland Islands and to the south 

 east of New Zealand. 



On the other hand, in the Arctic regions there is in the winter months 

 no such system of low jnessure in similar latitudes, but instead there 

 are two systems of low pressure, having a mean of 2!»'50 inches, which 

 are absolutely restricted to the northern portions of the Atlantic and 

 Pacific oceans. Over tlie rest of the Arctic regions proper tlu^ mean 

 atmosi)heric pressure exceeds 30-0(> inches, being, roughly speaking, 

 about the same as the mean pressure of London. In accordance with 

 this distribution of pressure, observations show that nortiierly winds 

 immensely preponderate over Arctic and sub- Arctic regions. The 

 large number of meteorological observations made during tiie ])resent 

 century in the high latitudes of the Northern Hemisphere idace these 

 tacts in the clearest light, and they are admirably lepresented by Dr. 

 Buclian in his new isobaric charts winch accompany the ClKdioif/cr 

 repoit. 



In the Nortiiern Hemisphere the land almost completely surrounds the 



" See Murray op. 'it., p. .535: 1886. The motion of glaciers is oltcn compared to 

 tliat of rivers and of viscous bodies; but these couiparisous are not strictly correct, 

 and may sometimes be misleadiiijf. T!ie jiecuiiarity of ice motion and its erosive 

 po^Yer appear to bo largely due to the fact tliat its melting or frerziug i)oiut varies 

 with temi)erature and pressure. The pre.<sure being uuequally distributed through- 

 out the glacier, minute crystals of ice are melted -where the pressure is greatest; the 

 resulting water occujjying less S])acc, regelation at once takes place, and where the 

 ice is wholly compact and crystalline jiressurc is exerted in all directions, motion 

 taking place in the path of least resistance. The immense thickness of ice some- 

 times invoked does not seem necessary to account for the erosive effects produced by 

 ghiciers. The stratified apjiearance of the southern icebergs is evidently due to the 

 constant melting and regelation which go on throughout the ice cap; in the deeper 

 parts of the bergs tbe.se layers are not tliicker than wafers, and where the ice is 

 Avholly crystalline the layers disappear altogether. 



