Washington May 23. 05.
I called yesterday at the Patent office to enquire respecting Macomb’s mill according to the request in your letter of the 15th. inst. there is a drawing of it, but no model; and no copy can be permitted to be taken from the office till the patent expires, which will be on the 28th. of August next. it is really nothing more than a bad edition of Barker’s mill, which no mode hitherto devised has been able to make equal to the grinding of grain. the horizontal wheel, with vertical laddle-boards in the edge, & a horizontal spout striking them is better than Barkers, but the same horizontal wheel of the size of a tub wheel, with laddle boards in the edge at the windmill angle (54° ¾) with a vertical spout is probably better; but whether either of them is equal to the tub wheel has not been sufficiently tried. none of them will do but where there is a waste of water. where that is scant, the breast or overshot wheel (according as the fall admits) is far preferable to all of them. should particular reasons continue your preference of Macomb’s wheel, you can at present only get the instructions from him, paying, I presume his patent price. but who or where he is, I know not. if you wait however till August I will have you furnished with a drawing. your application to me needs no apology. tho not so much master of my time for the service of my friends as formerly I am not entirely forbidden that privilege: and in availing myself of it for you, I am gratified by renewing antient recollections, and sentiments of unchanged esteem. present me in the spirit of early affections to mrs Hylton, and Accept yourself assurances of my constant friendship & respect.
DLC: Papers of Thomas Jefferson.