My dear D^r Gilbert

I sh^d. be the most ungrateful of men, if I were not greatly pleased by your letter. I beg you to thank M^r. Lawes most cordially for his most kind invitation.¹ It would have given me real pleasure to have accepted it, & I have always felt much curiosity to inspect the very interesting work at Harpenden; but in truth I have not strength enough to visit at any house. All that I could do, w^d. be to come to Harpenden & be introduced to M^r. Lawes, which I sh^d. very much like, walk about for an hour & see your plots & then return to London for the night— As it is we shall not leave this place until next month.² Therefore I must forego this to me great pleasure.

Once again allow me to thank heartily M^r Lawes & yourself for your most kind proposal, & believe me, dear D^r. Gilbert | Yours very sincerely | Charles Darwin