50 Report on Trials of Plows. 



Jefferson's generating line; one end of a twelve-inch rule carried 

 along from b to d', Fig. 49, and the other end along e c, Fig. 18, 

 will describe the twist of his mould-board in the air. The twist 

 of Small's mould-board is obtained by extending the cord d' b, 

 and suffering the slack to fall by its own gravity, when it will 

 assume the curve d' o b. One end of the ruler being carried 

 from b through o, along to d ', Fig. 49, and the other along the 

 line e c, Fig. 18, will describe in the air the twist of Small's 

 mould-board. By the substitution of a curved line for a straight 

 one, Small obtains a wider wing without making the fore part of 

 the plow too blunt, and thus insures the result so highly coveted 

 by the British plowman, of giving a high sharp crest to the 

 furrow. It is difficult to imagine any practical purpose which is 

 obtained in giving concavit}'^ to the parts above the transit line in 

 the fore part, and below it in the hind part of Small's plow. The 

 zero line o o, it wall he seen, makes a very small angle with the 

 line which at first was the bottom of the furrow slice, but which 

 has now assumed a vertical position, and hence there is a corres- 

 pondingly small tendency to break off or abrade the corner y, 

 which, when finally deposited, forms the crest. The angle thus 

 formed with the lower face of the furrow slice is much smaller 

 than in the Rotherham plow, which had a tendency to break off 

 the crest, and it is to this circumstance more than its superior 

 lightness and its improved mechanical construction that the great 

 popularity of Small's plow was owing. 



The next improvement in the plow" was made by Mr. Wilkie, 

 of Uddingstone, near Glasgow. We have used the word " improve- 

 ment;" we had better have used the word alteration, for until 

 this day it is not fairly settled that it is really better than Small's. 

 It is noAV generally known as the Lanarkshire Plow. The body 

 frame, which in Small's plow, Fig. 28, is made of cast iron, is 

 made of malleable iron in the Lanarkshire; the two arms, b and 

 c, instead of being bolted to the frame are welded to it, and form 

 prolongations from the beam and left handle. The bridle, coulter 

 and some other parts show trifling variations of form, but nothing 

 diflers in principle from Small's, except that it is provided with 

 two very useful appendages, which should be attached to all 

 plows, as they save much time, and their presence will induce 

 the plow^nan to temper his irons and keep the plow in nuieh 

 better condition for work than he Avould do in their absence. 



