Philadelphia June 16th 1808
When you have a leisure moment, I would take the liberty of requesting you to examine the enclosed design for a reaping machine, and to give me your opinion of the merits of the principle upon which it is founded.
My knowledge of agricultural subjects is so limited, that I feel diffident of introducing to the public notice a machine of this nature, before I receive the advice and opinion of such persons as are capable, both from their knowledge of mechanics & their application to agriculture, to give them; I would therefore Sir crave your indulgence while I solicit of you to gratify this my desire;—I feel the greater boldness to do this not only from having experienced your attentions in many instances already, but from a consciousness of the pleasure you will take to patronise whatever tends to the improvement of the highly beneficial art of agriculture.—It cannot but be admitted, that a machine of this description would prove a valuable acquisition to the rural economy for every one, the most superficially acquainted with agriculture knows the labor attached to the reaping of grain &c. & farmers are but too sensible sometimes of the difficulty of procuring hands to complete the reaping of their corn fields in season.—The possession of this machine would almost make the farmer independent of this extraneous labor. I am well aware that there are some situations which will oppose the operation of this machine, or at least render it difficult to be used, for instance in very hilly, stumpy, ridgy or uneven land, perhaps more so in ridgy land, which if the case, the evil will work its own remedy in time, as there is no absolute necessity generally to plant grain under this disadvantage.
The drawings which accompany this letter present only one method by which it is purposed to give the proper action to the scythes, viz, by a complete & undisturb’d revolution—There are two other methods, which from my not having time to digest them properly, I have not drawn, but which I will mention here, as perhaps you may approve of them under particular circumstances;—the first of these proposes, by a certain arrangement of machinery to put only one scythe into operation, and to give it such action as to resemble that, which is the result of human exertion—This method as well as the preceding, throws the action of the scythes entirely without or beyond the frame of the machine, there fore they are applicable to the reaping of grain, & the latter may be used for grass also—The last method that I think of at present & which is only applicable to grass, is to include the works entirely within the running wheels, let their distance &c be what they may.—The chief disadvantage attached to this is, that the horse or person that draws the machine is first obliged to pass over the grass to be cut, or if the machine goes before or is pushed by the power the grass will suffer the same fate, of being trodden upon.—
But as the machine I have drawn is of the most simple construction, I would beg leave to draw your attention particularly to the principle upon which it is founded, as if it possesses merit, such improvements may be made upon the arrangement of the parts as to suit almost every exigency—
The references on the same paper of the drawings are so much in detail, that it is scarcely necessary for me to enlarge further here. I will conclude after a few more remarks—
When the machine is to be put into operation, (as it can cut only on one side) it commences acting on the outside of the grain; while it is performing a revolution or circuit of the field, there must be a path prepared, before it takes another circuit, else the grain that has been cut down would be injured; this can be done by the sheaf binders.—I have represented 4 knives or scythes, but in this design 2 are quite sufficient; the sweep of one of the scythes is laid down very correctly, and where it makes a revolution, it is marked by a colour’d circle—
Anticipating the favorable reception of this communication and hoping your time will admit your indulging me with a reply, I have the honor to subscribe myself with sentiments of unfeigned respect and gratitude
Dear Sir yours
DLC: Papers of Thomas Jefferson.