From Richard Owen   Oct 11th 1864

British Museum, | October 11^th 1864.

My dear Tyndall,

I derive so much pleasure & profit from a study of your writings that I must thank you for kindly adding your 4^th. Memoir on Heat,¹ and the Paper on the Conformation of the Alps,² to my Series.

Your brain, physiologically speaking, is now at its best, & that it may long continue there is the hope & wish of.

Yours sincerely | R. Owen

RI MS JT/1/O/3