TKENCHING AND STJBSOILING. 



67 



nF is the resistance to be overcome, that is to say the 

 traction of the plough which we may designate as R ; 

 y 



is the speed of this resistance, which we may designate 



by 0, and we may write : 



FV k = R v. 



Let us notice that we lose a certain quantity of motive 

 power F x Y, for the co-efficient k is less than unity, but the 

 intermediate mechanism offers the enormous practical advan- 

 tage of enabling us to obtain, with the most advantageous 

 speed of the animal, a traction R of the plough as high as is 

 desired, on the condition, however, of diminishing the speed 

 v of the latter proportionately. We may recall the popular 

 expression " What is gained in power is lost in speed" 

 ' The mechanism used may be a gearing winding drum or 

 a capstan. 



According to Ferrouillat, Desforges relates.* (See page 18.) 



J. C. Loudon (Encyclopedia of Agriculture, 1831) men- 

 tions a mole-plough invented by Adam Scott, and improved 

 by Lumbert, of Gloucestershire ; this implement, penetrat- 

 ing very deeply into the soil, was hauled by a capstan 

 worked by four men or by a horse. 



The capstan was improved by Weir, of Oxford-street, 

 London. The figure in London's work gives a fairly 

 accurate idea of those in actual use.f We give, on account 

 of its historical interest, the Fig. 29, which shows one of 

 these capstans hauling a mole-plough. 



Fig 1 . 29. Lumbert's Mole-plough. 



* Rapport sur le concours special dt treuils a Narbonne, 1888. 



t See Loudon's Encyclopedia of Agriculture, 8th edition, 1883, page 401, 



