574 Proceedings of the Royal Society 
having an equal mean temperature, even though of small extent, 
and at a very short distance from one another, have an equal 
amount of range, and that the places on the earth’s surface in 
which these two conditions of equal mean annual temperature and 
equal annual range are the same, are very few and far between. 
Again, to show the variations of range in the same latitude, 
some of the parallels of the northern hemisphere have been opened 
out, as the isotherms were in the former instance, on both sides 
of the first meridian, and the range on each point projected up 
from these as before, giving curves analagous to that shown below 
the southern hemisphere of the accompanying range chart. 
One of the peculiarities shown by the curves thus produced, is that 
of the smallness of the range on seas and lakes, and the great amount 
on the land surface of the globe, as also the very immediate in- 
crease of range from some coasts towards the interior of the land. But 
by far the most interesting and curious feature presented by this 
diagram, or indeed by the whole subject, is that of the difference in 
the amount of range on the opposite coasts of continents and seas. 
In the temperate regions, and even to some distance beyond 
these into the torrid zone and the arctic regions, the range on coasts 
facing west is invariably less than that of coasts facing east , in the 
same latitude , and this holds good not only in the case of great seas 
and land masses, but also on the shores of inland seas and lakes. 
The comparison of the range at a few places in the same latitudes, 
but on the opposite coasts of the continents, given in the following 
tables, may serve to show the great amount of this difference. 
In North America — 
Latitude N. 
West Coast. 
Range. 
East Coast. 
Range. 
Difference of 
Range. 
67° 
Sitka, . . . 
23° 
( Port Nelson, \ 
< Hudson Bay, ) 
o 
o 
CO 
42° 
( Nain, Labrador, 
62° 
29° 
43° 
Port Orford, 
11° 
Boston, . . 
44° 
33° 
37° 30' 
San Francisco, 
8° 
( Richmond, ) 
\ Virginia, . ; 
40° 
32° 
32° 30' 
San Diego, Cali- ) 
fornia, . . ^ 
to 
f-* 
o 
( Charleston, S. ) 
} Carolina, . ) 
31° 
10° 
Mean Difference, 
. . . 
29° 
