162 



Report on Trials of Plows. 



Increase. 



PLOWS. 



Between , Between 



4 and 6 in . 



Per cent. 



Of Fergusson's . 

 Of Beverstone's 

 Of Barrowman's 

 Of Barrett's.... 



Average . . . 



21.21 



25.92 

 12.19 

 58.18 



29.37 



6 and 81 in, 



Per cent. 



50.00 

 88.23 

 32.01 



56.94 



Average 

 per cent. 



35.50 

 57.07 

 22.40 

 58.18 



43.31 



The average increase of power for each inch in depth ot Fer- 

 guson's plow was 7.90 per cent, or 84 pounds; Beverstone's plow 

 was 12.68 per cent, or 115 pounds; Barrowman's plow was 4.98 

 per cent, or 62 pounds; Barrett's plow was 12.92 per cent, or 103 

 pounds. Average, 9,62 per cent, or 91 pounds. 



Our own experiments on this point were very meagre, on 

 account of the mistake in sending ofl* the dynamometer heretofore 

 alluded to, but as the subject is of so much importance we give 

 them here. The experiment w^as made in a very hard soil, with 

 gravel indurated in the cla}^, and all the plowing was deeper than 

 any previous plowing, so that in each case the plow went into 

 soil which had never been disturbed before. The plow used was 

 Holbrook's No. 100; furrow ten inches wide. At 8^ inches deep, 

 659 pounds; at 10^ inches deep, 753 pounds — increase, 94 pounds; 

 at 12^ inches deep, 801 pounds — increase, 48 pounds. The aver- 

 age increase of power for each inch of depth in this case is 35 

 pounds, or 5.38 per cent. 



We can most fully corroborate the correctness of Mr. Pusey's 

 remark, that this is a very difficult experiment to make. It is 

 hard to preserve the exact depth of one inch more or less; some- 

 times it will run up or down considerably more than an inch. 

 Sometimes when plowing at a given depth the share will encounter 

 a mass of roots which resist very greatly, while in plowing an 

 inch deeper we do not encounter these obstacles, and the plow at 

 that depth does not appear to draw as heavily as it did when 

 plowing an inch shallower. Owing to these inequalities in the 

 texture of the soil at different depths, we need not expect to meet 

 with any very regular law of progression in the draught in the 

 indications of any particular table; but by having recourse to 

 averages, the indications of a uniform law of increase begin to 

 develop themselves sufficiently to assure us that when a sufficient 



