450 SCIENTIFIC EECORD FOR 1882. 



of the Caucasus. Thus the difference of mean temperatures at the lower 

 end of glaciers reaches as much as fully 20°. Besides, we see that, pro- 

 vided the quantity of rain and snow is great, glaciers descend as low as 

 212 meters above sea-level in a country (Is'ew Zealand) which has the 

 latitude of IS^ice and the mean temjjcrature of Vienna and Brussels — that 

 is, higher than Geneva, Odessa, and Astrachan — whilst the average tem- 

 perature of its winter is higher than that at Florence. Further, Dr. 

 Woeikoff discusses the rather neglected influence of large masses of snow 

 upon the temperature of a country during summer, and by means of a 

 very interesting calculation he shows how much the temperature of 

 summer in higher latitudes is below what it ought to be in consequence 

 of heat received from the sun, and vice versa in winter, these differences 

 being due on the one side to the refrigerating power of snow, and on the 

 other side to the heating power of ocean currents. In a following j)aper 

 he i)roposes to discuss the other causes which might have influenced the 

 climate of different parts of the earth during the glacial period. (Na- 

 ture^ August, 1881, XXIV, p. 364.) 



Woeikofl" contributes to the Zeitschrift fur Erdkunde a second memoir 

 on the climates favorable to glacier formation, in which he clearly indi- 

 cates the principal orographical and meteorological principles involved, 

 in accordance with the recent progress of meteorology. A cursory glance 

 over the present condition of our globe shows us that cold alone will not 

 produce permanent snow and glaciers when vapor of water is deficient. 

 There areno permanent snows nor glaciers in the Yerkhojansk Mountains 

 in Northeast Siberia, yet at the foot of them the mean annual temj)era- 

 ture is below 4° F., and that of January below— 56° F. The reason is 

 that the snowfall is but small, and thus the snow is easily melted in 

 summer. In New Zealand, on the contrary, owing to the enormous snow- 

 fall in the mountains, glaciers descend to about 700 feet above sea-level 

 on the west side (lat. 43° S.). 



At this height the mean annual temperature must be about 50° F., 

 and snowfall and frost are of rare occurrence even in winter.. The great 

 importance of an abundant supply of vapor being admitted, and thus 

 the necessity of surfaces covered by sea, what temperature of the surface 

 of the seas is the most favorable to the production of glaciers 1 This 

 depends certainly on the height above sea-level where the n6v6 is formed ; 

 but so far as we consider lowlands and moderate heights — say, below 

 6,000 feet — the surface temperature of the water should not very much 

 exceed the freezing point, otherwise the vapor evaporated from the 

 sea and condensed on the surrounding lands will be rain and not snow ; 

 thus contributing rather to melt the existing snow and not to form new 

 snow-layers. For lowlands and very small elevations a temperature 

 of the surrounding seas of about 32° F. is that which is most favorable 

 to the formation of snow, and if the last is falling in sufiQcient quanti- 

 ties to form permanent snow and glaciers. 



The deeper and opener the seas are, the better, for such seas do not 



