78 W. Hopkins on Changes of Climate. 
. 14. The next case I have proposed for discussion is that in 
which the Gulf-stream should exist, with a barrier of land con- 
necting Scotland with Iceland, and that island with Greenland. 
Since this barrier would intercept the influx of the Gulf-stream 
into the North Sea, it would very much reduce the temperature 
there, and in all the northern parts of Scandinavia. On_ the 
other hand, the waters of the Gulf-stream, being now confined 
to the northern part of the Atlantic, would considerably raise the 
temperature of that region. According to our preceding esl 
mate, the present increase of mean annual temperature due to the 
Gulf-stream is as follows :— Hi 
18°F. _ in Iceland ; 7°-5 F. at Snowdon ;__ 
~ 129-25 F. in the north of Scotland; 3° F. atthe Alps. _ 
. The mean annual temperature on the south coast of Iceland is 
now about 402. It is, I think, probable that this might be raised 
by 4° or 5° in the case supposed, which would make it approxi 
mate to the mean annual temperature of the English Channel. 
‘This effect on the mean temperature would be due principally to 
the effect on the winter temperature. If this latter were increa 
6° or 7°, and the summer temperature 2° or 3°, the January tem 
perature would be nearly uniform (or the January isothermal - 
would run nearly north and south) from Iceland to the latitude 
of the Alps or central France. The January isothermal of 32° 
now runs north and south through an equal extent of latitude 
rom a point several degrees north of the Arctic circle to the south= 
ern shore of the German Ocean. On the north of the barrier, 01 
the contrary, the variation of temperature would be more rapid 
than at present. | 
15, The next supposed case is that in which the whole Atlan-_ 
tic, from the equator northward to Greenland, Iceland and the 
North Cape, should be converted into land. In this case the! 
would be no reason why the isothermals should not preserve theif 
parallelism, with the exception of merely local deviations, from 
points near the east coast of Asia to corresponding points near the 
west coast of North America. Let us first consider the January 
isothermal of 32° FP. in the northern hemisphere. "os 
_ If we take this line as drawn independently of the disturbing 
influence of the Galf-stream, but supposing the Atlantic still 10 
exist, it is characterized by a northward inflection as it approaches 
the Atlantic, due to the influence of that ocean. In the present 
case there Is ho reason for that inflection, and we may assume 
isothermal to pass nearly in a straight line from the Black Sea 10 
the point where the actual isothermal of 32° F’. meets the coast 
of America. This will render its course nearly a straight line be- 
tween the opposite coast.of the single continent into which the 
two existing continents would be united in the case we are con- 
