340 W. Hopkins on Changes of Climate. 
Europe respectively could not, according to this theory, be eract- 
ly synchronous. Assuming, as we have done, the Gulf-stream 
to have existed during the supposed changes of level of the North 
American and European continents, it must have exerted its 
warming influence in the more northern latitudes, either as a di- 
rect current along the flanks of the Rocky Mountains, or as a re- 
flected one on the western coasts of Europe. The cold due to 
the absence of its influence in both these regions could not be 
strictly simultaneous, although belonging to the same geological 
r 
iod. This is an essential conclusion of the theory. I know 
lantic, and a similar difficulty must attach to the hypothesis of a 
shallow sea-bottom. The continuity of the northern anne 
e 
to avoid the far more difficult hypothesis just mentioned. J 
A note will be found towards the close of this volume on the isothermal ome 
illustrating this paper, issued with our March number. 
