532 //. T. Ferrnr—T/ic Antarctic Ice-cap. 



wbicli would by its own pressure liquefy its sole if the temperature 

 were 1 degree Fall, below its normal melting-point, and therefore 

 the limiting thickness of 1,G00 feet is far above the maximum for ice 

 resting on land at the melting-point of ice. 



At the "Discovery's" Winter Quarters, under the shadow of 

 Mount Erebus, latitude 77^ 51' S., longitude 166'^ 45' E., the mean 

 annual temperature was — 4G° F.,' and hence the point where 

 a temperature of 32° F. would be found must be below the surface. 

 Whether this point be well below the sole of the thickest ice has not 

 been determined, but as the glaciers are practically stationary their 

 ice must be out of reach of this temperature. A series of observations 

 of the temperature of glacier ice at fixed depths was made. The 

 observations were commenced in April, alter the temperature of the 

 ice had begun to fall, and extended throughout the following Winter 

 and Summer, until the month of February, when the ensuing fall of 

 temperature due to the increasing cold began. The highest 

 temperature recorded at a depth of six feet was — 9° C, and the 

 lowest — 24-4:'^C. 



The large difference between the maximum and minimum 

 temperatures recorded below the ice and the lag caused by the 

 six feet of ice would seem to show that the point which is not 

 influenced by seasonal variations is still deeper down. Now if we 

 take a value once adopted by a British Association Committee for 

 the earth's mean temperature gradient, we get a rise of 1° F. for 

 every 64 feet increase of depth. 'I'herefore, for a rise of 3G Fahrenheit 

 degrees (our mean annual temperature below the freezing-point) the 

 32° F. isothermal would be at least 2,300 feet below the surface. 

 On the inland ice Captain Scott's observations show temperatures 

 of 10°, 15°, or even 20° below those registered simultaneously at 

 Winter Quarters. Therefore the mean annual temperature on the 

 inland ico would be below the mean at Winter Quarters and the 

 32° F. isothermal surface proportionally lower down. 



Von Drygalski's results point to the same conclusion, but it must 

 De remembered — (a) that some of his temperatures were recorded 

 from crevasses which were open to the air and to water during the 

 Summer thaw ; {h) that in Greenland during Summer the air 

 temperature remains above the freezing-point of ice for several 

 weeks, and often rises 8 or 10 degrees above that point. 



Professor Schwarz does not seem wholly in favour of the view 

 that a warmei- climate in the Antarctic would produce a thickening 

 of the ice-cap, sufficient to exceed the physical limit.- The German 

 Antarctic Expedition and other earlier expeditions which remained 

 near the Antarctic Circle record a great snowfall as compared with 

 that experienced by the British Expedition in higher latitudes. 



1 All the temperatures quoted are our uncorrected values. Reference should 

 he made to the "Discovery" Eeports on Geology and Meterolojjy, which are to be 

 published by the British Museum (Natural History) and the Meteorological Office 

 respectivelv. 



■ Tyudall: "Heat a Mode of Motion," 1898, 11th edition, p. 231 ff. ; "The 

 Forms of Water," 1892, 11th edition, p. 154. 



