70 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 1 7, 



those of which the positions have been previously discussed, — the iso- 

 thermals of 32°, and the three succeeding it to the north. 



The approximate positions of the winter isothermals on the south 

 of that of 32°, and in the northern hemisphere, may be easily inferred 

 in like manner. It is not necessary here to discuss them in detail. 



Let us now take the July isothermals for the northern hemisphere. 

 In Asia there would seem to be no reason why they should diifer 

 materially in the present case from the actually existing lines. West 

 of the meridian of 60° E. the two lines of 36°-5 and 41°, delineated 

 on Dove's map, are manifestly affected by the Gulf-stream. The next 

 to the south, that of 4 5°* 5, together with the two succeeding lines, 

 follow the inflection of the northern coast of Scandinavia, and must 

 be considered as influenced in a small degree by the same cause. If 

 we place them a little more southward, but still allowing for the ten- 

 dency of the slight northern projection of the continent in that re- 

 gion to inflect these summer isothermals to the north, their positions 

 will be approximately correct for our supposed case. Further west 

 we must destroy the southward inflections produced by the Atlantic, 

 and continue the isothermals almost directly west to the most north- 

 ern points through which the existing ones pass respectively in the 

 north-western part of N. America, about the meridian of 130° or 

 140° of W. long. 



Again, the isothermals still more to the south may be considered 

 as unafl'ected by the filling up of the Atlantic, at the points at which 

 they meet the meridians of 60° E. long, (that of the Ural Mountains), 

 and at those of 100° to 120° W. long. Straight lines joining these 

 respectively would represent the isothermals of the intermediate space 

 independently of merely local variations. 



Taking the same places as before, we have the following results in 

 the case before us for their temperatures : — 





At present. 



Differ- 

 ence. 



Old and New 



Continents 



united. 



Differ- 

 ence. 



The Alps. 

 Temperature for January 



38F.1 

 73 1 

 55-5 



38F,\ 

 61 / 

 49-5 



36-5 F.\ 



56 



46-25 



30F.\ 

 52 J" 



39 



o 



35 

 23 

 19-5 

 22 



iIf.\ 



75 J 

 44-5 



-7F.1 

 66-5 / 

 29-75 



-22F.1 

 62 1 

 20 



-25F.\ 

 53 J 



14 



61 

 73-5 



84 



78 



„ „ July 



Mean annual temperature..., 



Snowdon. 

 Temperature for January 



.. Julv 



Mean annual temperature 



Northern Extremity of Scotland. 

 Temperature for January 



„ July 



Mean annual temperature 



Centre of Iceland. 



Tiilv 



Mean annual temperature (deduced "1 

 from the monthly temperatures). J 



