AGRICULTURAL ENGINES. 57 



he had so far progressed in 1813 as to construct thrash- 

 ing machines, portable agricultural engines, and steam- 

 ploughs to be moved by wheels as in locomotives ; 

 reaping, sowing, and other work, was also in future to 

 be the work of the steam-engine. 



A drawing by Trevithick having as usual neither 

 name, date, nor scale, nor writing of any kind, but the 

 watermark in the paper is 1813 illustrates his ideas 

 expressed to Sir Charles Sinclair in 1812: "It is my 

 opinion that every part of agriculture might be per- 

 formed by steam." The thrashing and grinding engines 

 were at work, and the tormenting harrowing engine 

 was probably designed for bringing under steam culti- 

 vation the extensive commons referred to. In those 

 days, before the practice of underground drainage, the 

 surface of cultivated land was thrown into furrows, or 

 a series of small hills and vales, the latter acting as the 

 surface drain for carrying off the water. 



Suppose the first step in cultivating a common to be 

 the breaking of the soil, and throwing it into uniform 

 lines of rise and fall that facilitated drainage without 

 inconveniencing the tillage, what better machine could 

 have been devised than Trevithick's ? A combination 

 of the modern tormentor and harrow loosened the 

 ground to the required depth, which was then, by a 

 revolving wheel with spades, thrown on one side, re- 

 sulting in uniform lines of ridges and hollows. The 

 steam-shoveller was removed, or the tormentor irons 

 raised, when 'only the harrow was required. 



The absence of the ordinary shafts at the front end 

 of the framing indicates that the spade-tormentor was 

 not to be drawn by horses, but whether by a locomo- 

 tive or by a fixed engine is not self-evident. 



