Mat 17, 1918] 



SCIENCE 



487 



5. Observers in the belt of totality are re- 

 quested to take the magnetic reading every 

 thirty seconds during the inten'al, 10 minutes 

 before and 10 minutes after the time of to- 

 tality, and to read temperature also every 

 thirty seconds, between the magnetic readings. 



It is hoped that full reports will be for- 

 warded as soon as jwssible for publication in 

 the journal of Terrestrial Magnetism and At- 

 mospheric Electricity. 



Louis A. B.\uer 



Washingtok, 

 May 8, 1918 



PROGRESSIVE DEGLACIATION AND THE 

 AMELIORATION OF CLIMATE 



Ix SciEXCE of March 1, 1918,^ Professor 

 Mather criticizes the interpretation of the 

 writer regarding the corroborating evidence of 

 Antarctic deglaciation as being indicative of 

 the amelioration of climate which has been a 

 cumulative, although variable, process since 

 the culmination of the Ice Age. This retreat 

 of Antarctic glaciation is not the only record 

 upon which the writer based his interpreta- 

 tion. He also used " the greater and still more 

 impressive evidence of the comparatively re- 

 cent uncovering of temperate land areas." ^ 

 Professor Mather appears to dissent also from 

 the opinions of Scott,^ Shackleton,* Taylor,' 

 Ferrar" and David." 



These authorities, with every other explorer 

 of these regions, make especial mention of the 



1 ■ ' Diminution of the Antarctic Ice Cap and the 

 Amelioration of Climate, ' ' Sciexce, N. S., Vol. 47, 

 No. 1200, pp. 218-19. 



7 Geographical Journal, Vol. XLIII., pp. 622- 

 623. 



2 Science, N. S., Vol. 46, No. 1200, pp. 639-40. 



3 ' ' The Voyage of the Discovery, ' ' Vol. II., pp. 

 416, 423, 424, 425. National Antarctic Expedi- 

 tion, 1900-1904, Vol. 1, p. 94. Scott 's Last Expe- 

 dition, Vol. II., p. 204. 



*Ib., pp. 286, 288. 



5 Address to Commonwealth Club, November 17, 

 1916. 



6 National Antarctic Expedition, Vol. I., 1900- 

 1904, Report of H. T. Ferrar, A.M., F.G.S., geolo- 

 gist of the Expedition. 



marked extent of the deglaciation which has 

 recorded its extent from "south pole to Ant- 

 arctic circle" (David). 



Professor Mather would also wait for ob- 

 servations extending over centuries and omits 

 to make note of the progressive deglaciation of 

 temperate latitudes which has legibly recorded 

 itself for several hundred centuries, within 

 which time the glacial lake beds of Canada 

 have become one of the world's richest grain 

 fields. This evidence is more impressive and 

 conclusive than the vast evidences in Ant- 

 arctica where " the ice is everywhere retreat- 

 ing " (Scott). 



Nor do discussions as to whether this de- 

 glaciation is due to wet or dry glaciers or to a 

 possible decrease in precipitation add anything 

 of moment to the great facts pointing to an 

 amelioration of the climate of the earth so that 

 it " is now warmer than it was during the 

 episodes of extensive glaciation characterizing 

 the Pleistocene Ice Age," this being due to the 

 rewarming under solar control inaugurated at 

 the culmination of that age. 



The vrriter does not agree with the idea that 

 the present distribution and development of 

 climates is " abnormal," but holds that it is 

 in the orderly development of climates passing 

 from the conditions of " geological climates " 

 into those of solar control ; and also holds that 

 present climatic tendencies and zonal control 

 no more point to a possible return to the non- 

 zonal distribution and control of geological 

 climates than the present developments of life 

 point to a redevelopment of the extinct orders 

 of life of previous ages. 



As to the climatic influence of carbonic acicl 

 generated by the combustion of fuels, carbonic 

 acid has two narrow bands of almost complete 

 absorption in that part of the spectrum limit- 

 ing the wave-lengths emitted by the earth. 

 These bands are at 4.5m and 14.7m. The first 

 is in a region of very slight terrestrial radia- 

 tion and therefore unimportant; the second is 

 in a region of strong vapor absorption and 

 there is sufficient water vapor in the air to 

 completely cover this field. Since " the effi- 

 ciency of the water vapor is several times that 



