CHAPTER XVIII.

AGRICULTURAL ENGINES; LOSS OF PAPERS.

Sir Christopher Hawkins's thrashing machine, 1812--Report of three wise men--Cost of horse and steam power--Wheal Liberty engine--Sir John Sinclair and the Board of Agriculture--Cost of engine--Power of engine--Welsh locomotive--Trevithick on steam agriculture--West Indies engine--Horse-power--Trevithick on patents--Engines in charge of labourers--Teapot--Detail of agricultural engine--Lord Dedunstanville's thrashing machine--Plymouth Breakwater locomotive--Wheal Prosper engine--Wheal Alfred engine--Steam-plough--Cultivation of commons--Combined steam-tormentor, narrower, and shoveller--Mr. Rendal's thrashing machine--Cost and work performed by thrashing engines--Their durability--Bridgenorth engine--Trevithick's drawings light the tires 36-68