WCP2881

[1]

Graveley

Huntingdon

9 Aug 1907

Dear D^r Wallace

I have tried hard to understand Lowell's¹ paper but have not succeeded. I can follow his arguement, but am stumped by his figures on p. 169. He does not make his meaning clear. For instance, he writes .20 x .50 x .50 = 60 percent, which is not true, because the product is really 5 per cent. It is not a misprint of 60 for 5, because 60 gives his result correct, but how he gets his .20 x. 20 x .50 beats me.

His table on the same page for the "heat received on the surface of the Mars and the earth" is all important but I cannot make it out how he gets the numbers 64 and 41.5. Granted that these are correct, I find the same value for the temperature of Mars that he does, viz. 72^o Fah.

He says that the albedo of the earth is 0.75, equal to that of Jupiter, while [2] the albedo of cloud is 0.72. It seems to me that the unclouded portion of the earth cannot reflect as much as the upper surface of cloud, so that the average must be less than 72.

Again, Jupiter being wholly enveloped in cloud, which the earth is not, the albedo of the earth must be less than that of Jupiter. But he makes it the same.

There is an article upon Mars in this month’s "Fortnightly" by Heward. He disagrees with Lowell, but does not refer to that paper in the Phil. Mag.

Believe me | sincerely yours | Osmond Fisher² [signature]

He make [sic] the albedo of [illeg.] more than the albedo of cloud!