From James Rumsey
London Octr. 4th 1789.
I have by the august packet, received a letter from one of the gentlemen, whome I am connected with in America, informing me that the Rumseian Society was upon the point of trying an Experiment, near Philadelphia, with my improved Barkers mill upon a large scale; and from the account I have receivd of the hight of the water, that is to work it, the dementions of the machine, and the purposes it is intended for; I am Sure it cannot Succeed, evin in a tollerable manner; my not knowing the quantity of motion, and force, that they want to produce, puts it out of my power, here, to Say how much they will be deficiant of makeing the application to the best advantage; I only know, that the purposes the mill are for (grinding Snuff &c.) requires too Slow a motion for my Barkers mill to Exert its powers to advantage, in the manner they are about to apply it. Its Excellence consists in moveing with great Velocity (in proportion to the head of water that turns it) without thereby looseing much of its power; it follows then, that its moveing Slow will not give it power, in proportion to what it will loose, by restraining it from motion yet nearly the Same quantity of water will be Expanded, that would if it moved five times as fast; which probably may be about the Velocity it ought to move with, in the above mentioned Experiment. The philosophy of this mill is not yet much known. Of Course the bad Success of this Experiment will Carry Conviction to the public, that it Cannot become usefull, and may make bad impressions upon the minds of my friends with respect to my other inventions; Especially as my Opponants will not fail to Set every misfortune that my Schemes meet with, in the most disadvantageous point of view; It is therefore Sir, that I have taken the liberty of troubleing you with this account, of what I Expect will be the fate of the Rumseian Societys Experiment of my Barkers mill; that my friends in Amirica, to whome you may be good enough to Communicate the contents of this letter, may Suspend their opinions respecting the utility of that mill, untill I have an opportunity of makeing an Experiment with it, under my own direction, when I doubt not of makeing it perform all that I promised the public to Expect from it.
In all next week I Expect to try my Vessel, and am Very Sorry that it was not in my power to get it ready, before you left Europe.
You have my best wishes for a pleasant Voige, and your Safe arival in Amirica. I am Sir with the greatest Esteem, y[our] much obliged friend, and Obt. hbl. Servt.,
RC (DLC); addressed and postmarked as in Trumbull’s letter, preceding; endorsed as received at Cowes 9 Oct. 1789 and so recorded in SJL.