From Erasmus Darwin7
ALS: American Philosophical Society
Lichfield Jan. 24, 74
I have inclosed a medico-philosophical Paper which I should take it as a Favour if you will communicate to the royal Society, if you think it worthy a Place in their Volum, otherwise must desire you to return it to the Writer.
I have another very curious Paper containing Experiments on the Colours seen in the closed Eye after having gazed some Time on luminous Objects, which is not quite transcribed, but which I will also send you, if you think it is likely to be acceptable to the Society at this Time, but will otherwise let it lie by me another year.8 I hope you continue to enjoy your Health, and that I shall sometime again have the pleasure of seeing you in Staffordshire, and am, dear sir your affectionate Friend
NB. If Dr. Franklin is not in England, I hope the Person intrusted to read his Letters will return the inclosed Papers to Dr. Darwin at Lichfield Staffordshire, which will be gratefully acknowledged.
Addressed: For / Dr. Benj. Franklin / Craven Street / Strand / London
Notation: Dr. Darwin
7. BF’s long-time acquaintance and intermittent correspondent. For his most recent extant letter see above, XIX, 210–12.
8. The medicophilosophical paper, entitled “Experiments on Animal Fluids in the Exhausted Receiver,” was read before the Royal Society the following March and published in Phil. Trans., LXIV (1774), 344–9. The unfinished paper was, we assume, an early form of one in which Darwin apparently collaborated with his son Robert: “New Experiments on the Ocular Spectra of Light and Colours,” ibid., LXXVI (1786), 313–48, reprinted in Erasmus Darwin’s Zoonomia; or, the Laws of Organic Life (2 vols., London, 1794–96), I, 534–66. For the evolution of this paper see Robert E. Schofield, The Lunar Society of Birmingham … (Oxford, 1963), pp. 272–4.