WCP566

[1]

[in ARW’s hand] Answd

10, AMPTON ROAD,

EDGBASTON,

BIRMINGHAM.

13 Dec^r 1907

Dear Sir

I thank you very much for the copy of your book¹ which you have very kindly sent me. I received it just as I left home & had the pleasure of reading it while I was away. I do not think that Lowell² could possibly answer your case against him if he was in a position to consider argument. But I doubt whether he is in such a position. His [2] belief is a crank & quite beyond reasoning.

I am sending you a copy of my Phil Mag³ paper. It translates into symbols much of your temperature argument. The lower temperature in elevated regions appears to come out from the alternation of day & night in a more or less satisfactory way.

The one point on which I do not feel convinced is the Johnstone Stoney⁴ argument that there is no water [3] vapour. The temperature of mars [sic] being too low, the molecular velocity is very much decreased & the vapors may be therefore retained. It seems to me still possible that the "snow caps" are ice crystals. But I do not think there an ever be melting. There may be sublimation & redeposition as hoar frost. This would I believe take place even at very low temperatures.

Again thank you for your book & for the pleasure which I have had reading it.

I remain | Yours faithfully | JH Poynting⁵ [signature]