1884. S5 Trans. N. V. Ac. Set. 



for luxuriance and variety, was found one species, Libocedrtis decurrens 

 (Heer), which is yet hving with the redwoods of California ; and 

 another yet remains on the Andes of Chili, while a third, according to 

 Dr. Gray, is the common taxodium or cypress of our Southern States. 

 In Gree'nland, lat. 70°, were found magnolias and zamias.* All the 

 teachings of palaeontology, especially as to the earlier periods, are 

 that there were then no zones of climate, and that there were warm 

 arctic seas all the year round. The evenness of temperature is most 

 extraordinary. Such a flora and fauna cannot exist where there are 

 great variations of temperature. Yet in these same regions, the sun, 

 if the earth's axis was inclined as now, was shut out for more than four 

 months, while for four other months it poured down without cessation. 

 Were a four months' night to settle down now upon the torrid zone, 

 the accumulated heat would soon be radiated into space, and when 

 the sun returned, no living thing would remain to greet it. 



It will help us to realize the enormous effect, if we remember that the 

 cold of our winters in our own latitude is due simply to the change from 

 long days of summer to the short ones of winter, plus the change in 

 altitude of the sun ; but how much greater would be the cold if the sun 

 went for four months below the horizon. 



It may be said that the cold was mollified by the latent heat of the 

 surrounding ocean, and by the influence of oceanic currents. But the 

 same capacity for giving off heat exists now, and the same currents 

 still flow ; yet in Spitzbergen, a not large island, surrounded by a broad 

 expanse of water, the cold is most intense. The specific heat of water 

 has not diminished ; so far as that is concerned, the ocean does as 

 much now as then to make the winters there mild, unless there is less 

 warm current. The effective cause of Gulf and other streams was 

 then, as now, the difference in temperature between low and high 

 latitudes. If that were nothing, there would be no current at all. A 

 small difference would produce some current, a greater difference would 

 produce a more rapid one. And this is true whether the currents are 

 due directly to this cause, or indirectly, through the medium of aerial 

 currents. In geological times the difference of temperature was much 

 less than it is to-day ; hence it seems within the bounds of truth to 

 say that the ocean currents then were no greater than they are now. 



Whatever warmth-producing influences existed in Spitzbergen and in 

 other high latitudes, their effect was no greater in winter than in sum- 

 mer. Admitting it to have been as great — a matter of reasonable 

 doubt — the temperature, as the days grew shorter, must have fallen 

 until it reached a point at which the loss of heat by radiation into 



* Dana's Man. Geol., revised ed., pp. 514 and 526. 



