50 THE MASSACHUSETTS SOCIETY 



agricultural society of that place. One or two communica- 

 tions were received from him by the Massachusetts society 

 at this period, and after he became finally domiciled in this 

 State he was a frequent correspondent. He, also, was an 

 observer and student of the plough, but bestowed the re- 

 sults of his thinking in conversation, and in letter writing 

 to friends, as opportunity might invite, without distinctly 

 claiming to be a discoverer of new principles of plough 

 construction, nor attempting anything concrete in that line. 

 In one of his letters he wrote thus : 



My employments in the war of the Revolution having 

 caused me to take my family to Philadelphia, I remained 

 there after its termination. During four years I lived in 

 the country and paid some attention to husbandry. One 

 day, learning to hold a plough (a good Pennsylvania plough 

 of that period), I observed that the earth, which was moist 

 enough to be adhesive, filled the hollow of the mould-board 

 and assumed a straight line from its fore-end near the 

 point of the share, to its upper projecting hind corner, and 

 that it maintained that same straight line. It then struck 

 me that this straight line should exist in every mould-board 

 and direct its curvature. 



At a subsequent period when in Philadelphia, visiting 

 Mr. John B. Bordley, vice president of the Philadelphia 

 Agricultural Society, he handed me a small model of a 

 mould-board which Mr. Jefferson had left with him. At 

 first glance I saw the straight line before mentioned govern- 

 ing its form, and, asking Mr. Bordley 's daughter, then at 

 her needle, for a piece of thread, I stretched it from the 

 lower fore part of the mould-board to its right upper over- 

 hanging fore corner. u Here," I said, to Mr. Bordley, 

 " is the principle on which this mould-board is formed." 



I have given this detail to explain the opinion I now ex- 

 press, that the straight line therein described is essential to 

 the form of the mould- board of the least resistance. 

 Around this line the curvature should be formed. And, 

 by placing the lower edge or bottom of the mould-board on 

 a level floor, if another straight line be laid transversely on 

 the fore end or point of the mould-board and moved regu- 

 larly back on its face, in a plane perpendicular to the hori- 

 zon, it will touch the mould-board in its whole breadth, 

 throughout its whole length, provided the curvature be 



