In justice to the favor you rendered me towards prosecuting my invention for propelling boats, I take occasion to inform you, that, after deliberate and correct experiments—(done however with imperfect works, and yet intended to be improved, and altered, even as to mode) I find the effect by hand, with the single stroke only, to justify the expected utility of the highest power that can be applied. I have produced a simple and sufficient resistance, and it only requires an equable and adequate force to render the invention publicly useful. The steam engine is my aim—and tho’ it has been objected to as applied to navigation, upon the principle of Boulton and Watts’s engine, as racking the vessel, yet that very objection may be entitled to a credit when fairly considered. I rather suppose that the failures heretofore have arisen from the modes of applying that power rather than that the power should be condemned. Surely Force is the primary object, and as surely can the strength of works be created sufficiently to withstand injury from that power.—Besides—my invention possesses the advantage of the alternate or successive resistance, so as to counteract the shock occasioned by the vacuum in the Engine, and perhaps only a partial resistance to meet with.—Be it however as it may, as regards the piston engine, I hope that some late inventions in steam, and others that are in progress to be matured, shortly, will produce that easy flow of power so much to be desired.—By the single stroke I have produced from 5 Miles to 5 and a half per hour, according to wind and weather and other circumstances—and by the adoption of an equable and durable force, allowing for additional resistance arising from increased velocity (if it is to be admitted in this case) I make up my mind that I can go 9 miles per hour, if not more, which will be sufficient to surmount the most of our currents to advantage. Until I can get a steam Engine to work, I shall rest my experiments.

I should do injustice to Doctor Thornton were I not to express a firm hope that he will succeed in a late idea he has hit upon with respect to steam.

I am Sir, with gratitude and respect, Your most obedient and humble Servant