ALS: American Philosophical Society
Passy. Monday March 29.—79.
I am extreamly sorry that I could not be present at your curious Experiments on Saturday, and that indispensible Business will prevent my waiting on you to-morrow: I shall be at liberty the rest of the Week, if some other day may be convenient to you; and will then attend them with Pleasure, being very sensible of the honour done me in your obliging Invitation. — I am, with great Esteem, Sir, Your most obedient & most humble Servant