P. E. Chase on the distribution of Heat over the Earth. 69 
mined by the direct heat of the sun, is at all times toward that 
int of the earth’s surface at which the sun is vertical, and we 
may readily believe that that tendency should be proportional 
to the distance, measured on a great circle of the earth, throug 
which the air would be obliged to move in order to reach the 
sub-solar point. This distance evidently varies as the are of the 
sun’s zenith-distance. 
Jan. 28352 Feb, 30-873 Mar. 39°049 Apr. 49°744 May 60902 June 69°780 
July 75-640 Aug. 71-154 Sept. 65°43 Oct, 53:922 Nov, 42350 Dec. 32°132 
Averaging the temperature at equal intervals from January 
(taking the mean temperature of Dec. and Feb., of Nov. and 
March, &c,), we get the following results. 
Months from Jan. 0 1 a 3 4 5 
Average temp, 28'352 31-502 40699 51°888 63-272 70767 75640 
Monthly diff, 8450. 12347 «28481 «84920 42-495 47288 
Ratio-of do. me 497 738 897 +~—«:1'000 
Be ls oes cues agen es a EE 
tance, 
The second of the above series of ratios (that of the differ- 
ences in the arcs of the sun’s zenith-distance) is based upon the 
ollowing estimate of the average monthly increase of solar alti- 
tude at all places in the temperate zones. 
Mos. from winter solstice, 1 i‘ 2 - : i ot aie “7 
— of solar canst pm ae 5 ee 45 931 1-000 
If we allow about 24 days for the cumulative effects of increas- 
ing heat and cold, these ratios become properly com arable with 
the monthly ratios of temperature-variation, as In the following 
table, which is compiled from the works of Dove and Guyot. 
é 4 : 
time, mos, 1 2 3 5 
Ratios of sines, 076 284 645 784 846 TF 
eae | 069 -255 500 745 ‘931 I 
N. Hemisphere, 076 259 ‘512 “763 935 1 
8. isph O11. 281.- 588. 168 938 : 
Arctic region, O71 231 479 “133 934 : 
Europe, 069 239 ‘501 “738 ae 
Asi “097 274 +535 a 
N. America, “055 «279 94 441. 917 se 
8. America, 017 275 ‘501 : 
Afri 088 ‘267 7 2 
Australia, 81-313 «618s "801-918 § 
