To Charles Lyell [28 November 1859]1
Ilkley Wells House | Otley Yorkshire
My dear Lyell
After all your trouble I am truly ashamed to give more. But I have not a Book here— Will you tell me from Principles how many kinds of footprints of supposed Birds feet have been found in the N. American Sandstone. My memory says 37 or 39 but this must be mistake.2 I can make good sentence leading to those suggested by you about Birds bones, in place of fossil Whale.—3 Merely write number on slip & send it me & excuse me.—
I am making great progress in sheets for 2d. Edit, correcting slightly but not adding from want of my fuller M.S.
Yours very truly | C. Darwin
Asks how many kinds of supposed birds’ footprints were found in North American sandstone.
Making progress on second edition of Origin.