394 SCIENTIFIC RECORD FOR 1884. 



ciers of New Zealand, showing that the present glaciers are as large 

 and extend to as low levels as those in Norway, while the mean temper- 

 ature of New Zealand is 11° C, as compared with 3° in Norway. The 

 cause of this glaciation is considered to be the greater humidity of air 

 and more' copious rain and snow of New Zealand, due to the greater 

 expanse of water in the southern hemisphere. The author considers 

 that the glacial period in New Zealand, during which the sounds in the 

 southwest coast were scooped and not filled up with dehris but since 

 which time the present small rapidly increasing alluvial deposits have 

 all accumulated, must therefore have been very recent. [A greater 

 exijanse of water in the northern hemisphere with a north polar conti- 

 nent would similarly give us higher temperatures and heavier gla- 

 ciers. {jS'ature, xxx, p. 651.) 



438. E. Hill, of Cambridge, England, has given a mathematical in- 

 vestigation of the efiect of fluctuations of solar heat and terrestrial ra- 

 diation upon terrestrial temperatures, and especially upon the glacial 

 epoch. He shows that the temperatures of the continents are now lower 

 under the present periodical change from day to night and from sum- 

 mer to winter than they would be if precisely the same quantity of heat 

 were communicated to them continuously and uniformly. The same is 

 also shown for the ocean ; periodical changes in the transmitted heat 

 increase the evaporation but diminish the radiation. An increase in 

 the amplitudes of these heat variations will exaggerate the increase or 

 diminution of the mean values of evaporation, &c. An increase in the 

 eccentricity of the earth's orbit exaggerates these amplitudes, and there- 

 fore lowers the mean annual temperature in the one hemisphere and in- 

 creases it in the other, also increasing the evaporation in the one hemi- 

 sphere and diminishing it in the other. Increased evaporation may 

 increase the snowfall. This is, therefore, possibly appreciable in con- 

 nection with the glacial epoch as discussed by Hill in the Geological 

 Magazine, November, 1881. {Z. 0. G. M., xix, p. 260.) 



439. W. F. Stanley maintains the improbability of the theory that 

 former glacial periods in the northern hemisphere were due to eccen- 

 tricity of the earth's orbit and to its winter perihelion. He quotes Fer- 

 rel and Hann to show that the mean temperature of the southern hem- 

 isphere is now equal to if not higher than the northern, although the 

 northern is the most glaciated, so that, whatever may be the relative po- 

 siticm of the earth's orbit and axis, it could have no more influence than 

 now lire vails. He explains glaciation as a local phenomenon, dependent 

 ujion the distribution of land and water and attending changes in aerial 

 and oceanic currents. {Nature, xxx, p. 526.) 



440. A. Blytt, by the study of the distribution of the plants of Scan- 

 dinavia at the present time and at the time of the formation of the peat- 

 bogs, concludes that since the glacial epoch the climate has experienced 

 periodical changes, in that dry continental periods have interchanged 

 with moist insular climates. These periodical climatic changes he traces 



