142 



Wheel and Swing Ploughs, 



which should be retained at right angles to the perpendicular ; and 

 to remedy which, unskilful ploughmen bear unequally on the 

 stilts, which produces a lateral pressure landwards, and conse- 

 quently a great amount of friction along the whole of the left-side 

 plane of the plough. However small may be the efforts of the 

 ploughman to keep his plough swimming fair/' those efforts 

 must be attended mth increased resistance, and consequently with 

 increased exertion of the horses. 



It is not pretended that in a wheel-plough none of these irre- 

 gularities of motion exist ; on the contrary, the dynamometer shows 

 them to be very considerable, but less in degree than in the swing- 

 plough. The oscillations of the index of a dynamometer are, as 

 might be expected, very great when applied to a plough. The 

 point of a ploughshare may be readily supposed, at one instant^ to 

 have burst a sod, which, opening and being raised upwards, offers 

 for several inches but a trifling resistance to its progress ; it again 

 meets the obstacle, which is again overcome. It is similar with 

 roots, stones, and other varying impediments, and thus at every 

 step of the horse (whose motion is also a series of impulses) the 

 draught, as exhibited by the dynamometer, is continually and 

 largely varying. 



These are effects arising from the nature of animal force and of 

 the soil ; they are necessarily commion to both ploughs, but appear 

 to be augmented in the swing, compared with the wheel-plough, 

 and sufficiently account for the diminished draught of the latter 

 as shown in the Table of Experiments. 



In order to satisfy myself more particularly as to the draught 

 of ploughs, I requested the Messrs. Ransome, of Ipswich, who 

 are the most extensive manufacturers of ploughs in the kingdom, 

 to furnish me with the opportunity of ascertaining the fact in 

 respect of those implements which they themselves had con- 

 structed. A stubble-field, of a sandy loam, was selected ; partly 

 up and down hill, and partly on a level. The ploughs, all by the 

 same maker, were set to the same gauge, viz., furrows 6 inches 

 deep and 10 wide, drawn by a pair of horses abreast, and held by 

 the best men that could be procured, who were occasionally changed 

 from one plough to another. The instrument employed to test 

 them was a draught- dynamometer, on Regnier's principle, and 

 which had previously been proved, by the suspension of weights, 

 to register with accuracy. This dynamometer consists of two flat 

 plates of steel, of a curved form, and increasing in thickness towards 

 the ends, which unite into solid cylindrical loops, the curved sides 

 of the plates being placed opposite to each other, and the whole 

 forming an entire elliptic spring. On the application of this 

 instrument as a link in the line of draught, the oval becomes 

 lengthened in proportion to the degree of force acting on the loops 



