To William Thompson   18 February [1846?]¹

Sir

I am much obliged for your kindness in sending me the note on the Atlantic Dust, as in case I ever get many more facts together, I may perhaps publish an additional note.—

With respect to the migration of Birds, it would be a sincere pleasure to me to aid, even in the smallest degree, one whose writings I have for several years been accustomed to read with much pleasure & instruction; but I really have nothing to say: I apprehend Forbes alluded to a mere speculation of mine (not grounded on facts & therefore quite useless to anyone) that birds probably followed lines of now lost & sunken land. I merely alluded to this notion of mine, when talking with Forbes on his views on the distribution of plants on land since subsided.— In some future year I intend publishing on the variation of plants & animals in the domestic & natural state, & I shall then (I fear) not be able to refrain from some speculations on this & allied subjects, but, as I have said, I really have no facts, or speculations of sufficient importance to be at all worth communicating in detail.— I am sorry that you sh^d. have had the trouble of writing for nothing; but may I be permitted to hope that our communication on paper may some day lead to our personal acquaintance.

I shall look forward with interest to your work containing your observations: I beg to remain, dear Sir | Your faithfull & obed: sevt. | C. Darwin