naan 
line of 22° Reaumur, or 811° Fahrenheit, which had been formed in the Carib- 
bean Sea in May, now embraces the whole of that sea and the entire Gulf of 
Mexico. In the southern hemisphere the curves have become extremely 
flat ; and even the difference between the east and west sides of South America 
is less sensible. The cooling effect produced by the melted drift-ice has 
undergone a considerable diminution. 
In July the extreme temperatures manifest themselves; within the elon- 
gated space enclosed by the isothermal of 24° Reaumur, a space enclosed 
by an isothermal of 26° Reaumur, or 901° Fahrenheit, has been formed, 
including Nubia and Southern Arabia. ‘These are the countries of which 
Hagi Ismael says the earth is fire and the wind flame. But in Western 
India also the temperatures have become since May extraordinarily high. 
The Afghans say, ‘‘Great God, why needest thou have made Hell when 
there is Ghizni?” It is no wonder therefore that the S.E. trade in the. 
form of a S.W. monsoon follows up the retreating N.E. trade to the foot of 
the Himalaya. In Europe and Asia the isothermals have overpassed the 
circular form (2. e. coincidence with the parallels of latitude), and begin to he 
convex in the interior of the continent. The thermic normal, enclosing a 
space warmer than the normal condition, includes all Asia, Europe, and Africa 
down to the equator; only Scotland and Ireland belong to the proper sea 
climate, as do also Labrador, Canada, New North and South Wales, and the 
margin of coast from California up to the mouth of the Mackenzie River. 
In the warm space of the Mexican Gulf, we find no traces of temperature 
so high as those of Africa and Hindostan; Maracaybo only reaches 24° 
Reaumur, or 86° Fahrenheit. The thermal limit between the northern and 
southern hemispheres is a little advanced towards the north in this part of 
the globe, but on the eastern side it touches the northern tropic in several 
places. 
The longitudinal axis of the isothermals runs westward from the Aleutian 
Islands towards Baflin’s Bay, but the issues of the Icy Sea, the Karian Gate, 
and Barrow’s and Behring’s Straits, draw out the circular form of the 
isothermal surrounding the pole into a more nearly triangular shape. . As 
in North America the isothermals have moved laterally, their concavities 
having advanced from the interior to the east coast, while in Europe and Asia 
the concave form has been changed into a convex one, their July course in 
the greater part of North America, in Europe, and in Asia is perpendicular 
to the direction which they follow in January. In the southern hemisphere, 
the isothermals, from 12° to 1° Reaumur, or from 59° to 34°°2 Fahrenheit, 
are thickly crowded and extremely flat. 
In August, in the old continent the east side of Nova Zembla alone resists 
the still continuing tendency of the curves to become more convex, and 
hence they assume two characteristic convexities, one at Spitzbergen, and the 
other beyond the mouth of the Lena. But on the coast of Greenland, as the 
cold in the high north already begins to increase, the drifting of ice to the 
southward is lessened, and the east coasts of North America are thus per- 
mitted to retain more of tle heat they receive, and the isothermal curves 
become fiatter. 
In September this is the case in a still greater degree ; and as the cold from 
New Siberia now begins to invade the continent of Asia, the convex summits 
are similarly flattened. This therefore is the season when the distribution of 
temperature over the globe is most regular, even America forming no ex- 
ception. Now begins the Indian summer, “ the time which the Great Spirit 
of the Red-skin sends to him that he may follow the chase.” The same 
ON THE MONTHLY ISOTHERMAL LINES OF THE GLOBE. 95 
is 
‘ats 
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