W. Hopkins on Changes of Climate. 77 
of 639-5 F., which passes immediately south of London, seems 
not to feel it in any sensible degree. ‘This isothermal, therefore, 
and all those to the south of it may be considered to have the 
same positions in our hypothetical ease as in the existing one. 
Those immediately on the north of the isothermal of 63°-5 must 
necessarily be approximately parallel to it. We observe also, as 
these lines approach the coast of America, they suffer an anoma- 
lous deflection to the south, due, I imagine, to the polar current 
setting. southwards along that coast from Davis’s Straits, the 
warm season being that in which this cold current would be 
most felt. 1 have drawn the isothermals for our supposed case, 
as independent of these anomalous deviations, and such as their 
actual positions on the east and west of the region of these irreg- 
ular influences obviously indicate. It would hence appear, that 
the Gulf-stream has no sensible influence on the July temperature 
of Loudon, or of places in western Europe further to the south. 
13. We are now prepared to estimate the effect produced by the 
Gulfstream on the mean annual temperature of any assigned 
place. The following are the approximate numerical values of 
the temperatures for January and July, and the mean annnal tem- 
Perature, considered as the mean of those two temperatures, for 
"Me Alps, Snowdon, the northern extremity of Scotland, and cen- 
terof Iceland ; both for the present time, and for our hypothetical 
case, in which, it will be recollected, the configaration of land and 
Sea IS Supposed to be the same as at present, but the Gulf-stream not 
to exist. The temperatures are all determined by Dove’s map. 
: At present, | ~ 4 Without i ets 
H ut in Difference. 
ee eile eo 
‘! @)\ THE ALPS. Rn CE Cree ey. : 
F ¥ °o " 
Temperature for January $3 38 st gee “4 F. t 39 
Pete. Siete” uly gt, 1S re 
Mean annual temperature, . , 555 ae 53:5 
es ea eNOWnEN... ~ ; | 
Temperature for January, . ; | 38 Ft © 23 F. di 
M OPS ides Ne HR Vy: ae es 61. i ba ° 
annual temperature, .  , 495 , 42 
NORTHERN EXTREMITY OF BOOTLAND. }}) 2) 
Temperature ¢ for January, . | 868 -F. 12 3 ii 
Mas a dele, coociiact eh aoe Lid 56 
j- "Annual temperature, . . | 46-25 34 
Re ; OF ICELAND, 
Temperature for January, . . | 30 i 92 —4 vo 50 
Vean, ee eer 52 46 
Mean a pti . . . . . 41 pai 
a" smnual temperature,* | 2 | 39 
er cone eat 
* SGA? RES ada om the f the monthly temperatures. TI an annus 
from tho nes above ivan foe the cihier cases is almost identical with those deduced 
be ae Monthly temperatures, ‘The discrepancy of 3° in the ease of Iceland may 
attributed to local li ray 
