I send, herewith, the little pamphlet I mentioned in my Letter a few days since. I am in hopes it may amuse thee a few hours, & that thou wilt favor me with thy opinion of the principles I have laid down, & of the utility of my invention. The numerous & expensive experiments which I have made on this subject, shall be, in due time, detailed for some Literary or philosophical Society. I have a high opinion of this invention—& so confident am I of its ingenuity & usefulness, that I almost, persuaded myself to presume on dedicating the pamphlet to my Hond Friend, the late President Jefferson. If I had done so, should I have done wrong? Or would my venerrable friend have objected to it? Please distribute the spare copies, at thy discretion. I much regret that I could not have seen thee; & I hope thy goodness will excuse me, if I ask; should I never see thee, some small trifle as a memento. With the most cordial & respectful esteem, thy grateful, obliged