980 



The Shrawardixe Tractor Trials, 1921. [Feb., 



appreciated. Empirically it is possible to evolve a mouldboard 

 for a greater speed by increasing the length and pitch of the 

 breast. The result would be the same quality of work at a 

 greater speed. It is not,, however, suggested that this would 

 solve the problem, the magnitude of which is fully appreciated. 

 In fact, before any really good design can be evolved it will be 

 first necessary to carry out experiments on the relations between 

 the design of cultivation implements and their effect on the soil. 

 Investigation will have to be made on the lines of the effect of 

 resistance in relation to such factors as speed, type of soil, 

 moisture content, coupled with laboratory experiments into co- 

 hesion, plasticity and relative motion of soil particles over the 

 mouldboard. the inversion of the furrow slice and other factors. 



The problem is not one which concerns the tractor alone. It 

 is by no means certain that the tractor represents more than a 

 transitory method of applying power to agriculture. In many 

 ways it is a clumsy and unsatisfactory unit, consuming in trans- 

 porting its own bulk energy which should be employed in cultiva- 

 tion. A cheap and easily operated system of cable cultivation, 

 whether by using internal combustion engines or electricity, 

 crude oil or coal, may very well displace tractors : but the ques- 

 tion of speed is as vital here as anywhere. We have been 

 informed that with steam cable sets the economical speed for 

 ploughing is about 3J miles an hour, and that this is the limit 

 because of the unsatisfactory nature of the work performed at 

 higher speeds : but the ultimate survival of any system will 

 depend upon the extent to which use is made of any special 

 advantage which it offers. 



Implements. — Little can be said of the actual performances of 

 the implements, since the data collected do not take one very far, 

 and the conditions were far from normal. The implement which 

 attracted most attention was the Kansomes sub-soiling plough. 

 It was to be regretted that the work done in the first field it 

 entered was neither a satisfactory nor a typical exhibition. An 

 attempt was made to sub-soil unnecessarily deep and a tine was 

 employed which appeared to be too wide — although upon this 

 point no definite opinion can be expressed without more experi- 

 mental data than are at the moment at the command of the 

 writers : the result, however, was that a heavy clay sub-soil was 

 inverted. Better work was performed in rather lighter land, 

 where a less arduous task was attempted : but far better work, 

 indeed, from a mechanical point of view, perfect work has since 

 been performed by this implement at a drainage demonstration 



