From George Gabriel Stokes   28 May 1863

Lensfield Cottage Cambridge | 28 May 1863

My dear Tyndall,

I return you your paper¹ by book post, partly to let you see a few trifling alterations, but mainly with reference to a point in p 11.

“Precipitate the act of condensation” p. 8 struck me as very odd immediately after the use of precipitation in its technical (i.e. meteorological) sense. On first reading I expected “water” or “vapour” instead of “the act” to follow precipitation.

Now for p. 11, there is no reference given. I referred to Leslie’s² book on heat,³ but it is weary work to hunt out a single sentence in a book without an index or even table of contents. So I was unable to judge from the context what Leslie’s views might have been. But it is to me perfectly inconceivable that Leslie should have supposed that the vapour acted by its pressure. I feel pretty sure either that “pressure” was a misprint for “presence”, or, which is more probable, that as we frequently speak of tension (a most unhappy substitute for pressure) of aqueous vapour as a measure of, or rather mode of expressing, its quantity, so here Leslie used pressure as tantamount to quantity.

An eminent man is not to be lightly charged with a bit of utter nonsense. If the context supports the charge, well; but I think the reference should be given to enable the reader to judge <Hereafter LT Transcript Only> for himself. But if my suggestion seems to you correct or probably so, the passage should be altered.

Thank you for your article in the Phil. Mag.⁴

Yours very truly | G. G. Stokes

Proof by book post.

RI MS JT/1/S/232

RI MS JT/1/TYP/4/1387