I recieved last night yours of the 3d. the volumes of the Oiseaux de Buffon which I possess are bound in that kind of binding which has been most common in France for many years, spotted, the leaves red on the edge, and double lettered on red.   the two pieces you sent me on printing & the polytypage are so curious, & on so interesting an art, that I propose to keep them with your leave. I knew Hoffman well, went often to see his works, & was intimate with the Abbé Rochon having myself tried several of his processes; so that the facts in that portion of the history are well known to me.   I presume you recieved my letter of Apr. 29. Accept my salutations.