June 22, 1906.] 



SCIENCE. 



931 



curred in India, Australia and South 

 Africa in the later coal-forming stages of 

 the Paleozoic era, the areas even lapping 

 upon the Tropics of Cancer and Capricorn ; 

 yet figs and magnolias have grown in 

 Greenland since. We are thus compelled 

 to face oscillations ranging from subtrop- 

 ical congeniality within the polar circles 

 to glaciation in low latitudes, and these in 

 alternating succession, while none of the 

 oscillation was permitted to swing across 

 the narrow limital lines of organic endur- 

 ance. There is little doubt that the ocean 

 is one of the most potential agencies in con- 

 trolling these oscillations and it is one of 

 its climatic functions that invites our pres- 

 ent attention. The carbonation of the 

 ocean is subject to wide variations and the 

 rapidity of this seems to be dependent 

 chiefly on deep-sea circulation. In an en- 

 deavor to estimate the rate of this, it was 

 found that the agencies that worked in op- 

 posite directions in promoting deep-sea cir- 

 culation were very nearly balanced, whence 

 sprang the suggestion that if their relative 

 values were changed as much as geologic 

 data imply, the direction of the deep-sea 

 circulation might be changed, and that this 

 might throw important light on some of 

 the strange features of geologic climates. 



The abysmal circulation is now domi- 

 nated by polar agencies, as shown by the 

 low temperature of the bottom waters even 

 beneath the tropics. Cold waters creep 

 slowly along the depths from the polar 

 seas equatorward, where they gradually 

 rise to the surface and return on more 

 superficial routes. 



The several influences of the winds, of 

 atmospheric transfer of water, of differ- 

 ences in salinity and of differences of tem- 

 perature, including freezing and thawing, 

 were then discussed. Charts of the exist- 

 ing temperatures and salinities showed a 

 close struggle between these opposing 

 agencies. More saline but warmer waters 



both overlie and underlie less saline but 

 colder waters. Computation of salinity- 

 effects and temperature-effects also indi- 

 cates a very close balance between the op- 

 posing agencies. 



Now in the majority of geological periods 

 the evidence of life indicates the absence 

 of very low temperatures in the polar re- 

 gions. Hence the inference that, at such 

 periods, the balance would lie on the side 

 of salinity and that therefore the deep 

 oceanic circulation would be actuated by 

 the dense waters of the evaporating tracts. 

 These are supposed to have slowly de- 

 scended and crept poleward, where they 

 rose to the surface and gave their warmth 

 to the atmosphere. Aided by the en- 

 shrouding mantle of vapors that must have 

 arisen from such a body of water, it is con- 

 ceived that the mild temperatures requisite 

 for the maintenance of the recorded life 

 through the polar nights may have been 

 thus maintained. 



Elementary Species in Agriculture: Pro- 

 fessor Hugo de Vries, of Amsterdam, 

 Holland. 



An International Southern Observatory: 



Professor Edv^akd C. Pickering, of 



Cambridge, Mass. 



A plan, possessing some novel features, 

 for a telescope of the largest size was pro- 

 posed, in which the best location, form of 

 instrument, cost, administration and dis- 

 cussion of results were considered in turn. 

 The best location in the world is desired, 

 and is probably in South Africa, west of 

 Bloemfontein, or in Peru. The relative 

 advantages of reflectors and refractors 

 were compared, with the conclusion that a 

 reflector of seven-feet aperture and forty- 

 five-feet focal length would be the best. 



The great observatories of the world have 

 each a plant costing two or three hundred 

 thousand dollars, and an annual income of 



