462 Climate of the Glacial Period. [October, 
the axis of Jupiter proves that there is nothing impossible 
in the supposition that that of the earth may also have 
been perpendicular to the plane of its orbit. The immediate 
effect would be the equalisation of night and day all over the 
world. With twelve hours’ sunshine and twelve hours’ 
darkness the seasons would disappear, or rather every 
parallel of latitude would have but one. At the equator 
alone would the sun rise dire¢tly overhead at noon. In the 
temperate zones would reign perpetual summer; within the 
Arctic circle perpetual spring. In Central Europe sub- 
tropical vegetation might then flourish. In North Green- 
land the sun every day would rise to a height of 20° above 
the horizon. 
The forms of the continents were very much the same as 
they are now. It is probable that the Gulf Stream exercised 
the same sort of influence as it does at present on the climate 
of the North Atlantic, and it is significant of that influence 
that the most northern Early Tertiary forests have been 
found in Spitzbergen, whose shores it now laves. The 
flora of North Greenland suggests that a branch of the 
Gulf Stream also flowed up along its western coast. With 
twelve hours’ sunshine, ice could not accumulate in Baffin’s 
Bay, and it is not improbable that some of the warm surface 
currents of the ocean then found a passaget hrough Davis’s 
Strait towards the Pole. Under such circumstances the 
west coast of Greenland might have its mean temperature 
raised as much as Prof. Heer thinks is necessary. During 
the day twelve hours’ sunshine would give it the heat of a 
mild summer’s day, and at night the warm currents flowing 
past its shores would prevent the occurrence of frost. The 
sequoia and the magnolia might then flourish and perfect 
their fruits in North Greenland; and even at Spitzbergen 
the Gulf Stream might cause frost to be unknown ; but there 
the sun would rise to such a small altitude that the climate 
would not be warm enough excepting for hardy northern 
trees. 
Whilst the cold of the Glacial period and the heat of the 
Early Tertiary period might thus be caused by a great increase 
or a great decrease respectively of the obliquity of the ecliptic, 
the extreme point to which the ice reached southwards, as in 
America, and that to which vegetation reached northwards, 
as in Spitzbergen, were both due to geographical conditions 
still in existence. In both periods we have evidence that the 
isothermal lines were deflected far northwards by the Gulf 
Stream, and that the east coast of America was much 
colder than the west coast of Europe. The evidence is 
