From Thomas Coleman Martin
King & Queen [County] Octr 16 1797
I have the honor to acknowledge the receipt of your Letter of the 3d instant and it will afford me great satisfaction if the answer I am giving shall contribute to yours.
I have invented a machine for seperating the grain from the straw of wheat & other small grain which bears but a small degree of analogy either to the Scotch machine or Mr Bookers as I had no knowledge of either at the time of this invention.
The plan of this machine is so simple that its workmanShip would fall within the compass of twenty dollars and as it has no bands & but few wheels it cannot easily be disordrd—of corse in case of an accident (which is hardly possible) it would be easily repair’d.
The first I invented is worked by water by the help of the shaft of a small ⟨tred⟩ mill the upper stone of which is removed for the purpose. Sixteen square inches of water under a pressure of six feet discharged upon a ⟨sub⟩ mill wheal of two feet diameter is sufficient to give one machine the requisite velocity. The force bestowed by this power is competent to the geting out in great perfection three bushells of wheat in seven minutes with three hands to attend the machine. But as this is the effect of a first essay I can venture to assert that the same power is adequate to a greater degree of execution.
This discovery has been so recently carried into execution that I have not yeat been able to apply for a patent though it is my purpose to do so nor have I fully satisfied myself how far it may answer if worked by a horse or hand. An experiment however which I have made in the latter mode encourages me to hope that, in this way also the machine may be of considerable utility.
This machine is as small as to be quite portable in a common wagon and therefore a house of very small dimentions will suffice—any barn whatsoever is abundantly sufficient to work it in.
As it would be hardly possible that a compleat idea of the machine could be colected from a ritten discription I will not trouble you with one—permit me only to observe that the chief complexity of it is comprised in four plain cogwheels the larger of which is three feet diameter and a perpetual screw of easy imitation.
Altho I purpose to apply for a patent yet as the good of mankind was my chief motive for turning my thoughts to this and other semilar objects so I have made no secret of my efforts nor of the results arising from them Here the machine has been submited to ⟨an⟩ discriminate examination as that which it could say for itself would have most influence towards bringing it into general use And if upon farther examination it should prove itself worthy of your patronage it will greatly incourage my hope of haveing contributed towards the publick good. I am with all due respect Sir yr mot obt Servt
Tho. C. Martin