48 W. Dennis on the Temperature, &c. 
other they both conspire to produce the same result. The cold 
of winter not being, like summer heat, produced by the sun 
but by radiation or loss of heat in spite of the sun’s influence, 
(a point that seems not to have been sufficiently attended to by 
some writers,) it happens that the two conditions referred to 
have a different relation to each other in the two opposite sea- 
sons, being as just stated opposed to each other in the one case 
while in the other both contribute towards the same result. 
hus in our northern winter not only is the sun near its mini- 
mum distance throughout the whole period in which the princi- 
pal reduction of temperature takes place and during which it is 
most rapid, but the period itself is materially shortened. For 
these combined influences there seems to be no effective com- 
pensation, and it can hardly be doubted that the present arrange- 
ment gives to our northern winters a character very considera- 
bly different from that which they would present were the posi- 
tion of the line of apsides reversed. It is remarked by Her- 
schel, in reference to the southern summer, that “ j.th is too 
considerable a fraction of the whole intensity of sunshine not to 
aggravate in a serious degree the sufferings of those who are 
exposed to it.” But in this case not only is the winter reduction 
of temperature counteracted by the addition of this ‘considerable 
fraction’ to the supply, but the é’me of rapid reduction is shortened 
by about jth of its whole amount. Under these circumstances 
In the southern winter the two conditions also combine, but 
their joint effect in this case takes the opposite direction. The 
cooling process by which the temperature is gradually reduced 
at this season has its rate increased by the increased distance of 
the sun, and the time during which this high rate continues 18 
extended. While therefore the effect of the present position of 
the earth’s orbit is to make the winters of the north milder, 1ts 
tendency to make those of the southern hemisphere more S8é- 
vere is equally decided: and could a comparison of the two be 
instituted on the basis of actual observation under conditions 
any tolerable degree similar the contrast would doubtless be 
iking:> But <i : 
com n impracticable. The small portions of 
the two continents extending into the south temperate zone are 
