Distribution of Heat over the Globe, S6S 
which is as it were the isothermal equator, and that in America 
and Asia through 78° of west, and 102° of east longitude, the 
torrid zone commences more to the south of the tropic of Can- 
cer, or that it there presents temperatures of less intensity. An 
attentive examination of the phenomena proves that this is not 
the case. Whenever we approach the torrid zone below the 
parallel of 80°, the isothermal lines I?ecome more and more 
parallel to one another, and to the earth’s equator. The great 
colds of Canada and Siberia do not extend their action to the 
equatorial plains. If we have long regarded the Old World as 
warmer between the tropics than the new world, it is, firsts Be- 
cause till 1760, travellers used thermometers of spirit of wine, 
coloured, and affected by light ; 2c?, Because they observed it 
either under the reflection of a wall, or too near the ground, 
and when the atmosphere was filled with sand ; and, 3c?, Be- 
cause in place of calculating the true mean^ they used only 
the thermometric maximum and minimum. GcK)d observa- 
tions give. 
Old World. 
Lat. 
Mean Temp. 
New World. 
Lat. 
IMean Temp. 
Senegambia, 
15° 0 
79^07 
Cumana, 
10° 27 ' 
81°.86 
Madras, 
13 5 
80 .42 
Antilles, 
17 0 
81.05 
Batavia, 
6 12 
80 .42 
Vera Cruz, 
19 11 
78.08 
Manilla, 
14 36 
78 .08 
Havannah, 
23 10 
78 .08 
The mean temperature of the equator cannot be fixed be- 
yond 8H°. Kir wan values it at 84°, but only two places of the 
earth were known, viz. Chandernagor and Pondicherry, to 
\vhich old travellers attributed annual temperatures above 81°J. 
At Chandernagor, in latitude 21°,6, the mean temperature, ac- 
cording to Cotte, is 91°.9, but the Jesuite Boudier marked only 
the days when the thermometer was above 98°. 6, and below 
57°.2. And at Pondicherry, in latitude 11° 55', the mean tem- 
perature, according to Cotte, is 85°.3, and according to Kirwan, 
88” ; but M. de Cossigny observed with a spirit-of-wine thermo- 
meter. 
The distribution of heat over different parts of the year differs, 
not only according to the decrease of the mean annual tempera- 
tures, but also in the same isothermal line. It is this unequal 
division of the heat which characterises the two systems of 
chmate of Europe and Atlantic America. Under the torrid 
zone, a small number of months are warmer in the Old World 
than in the New, At Madras, for example, according to Dr 
