SECT, ix.] OF STEAM ENGINES. 283 



winnowing grain, chaff-cutting, grinding bones for manure, and to grinding corn 

 for fatting cattle and for family uses. 



The boiler may be further applied to steam food for cattle. No other objects 

 occur to me, except to notice, that for drainage in fenny districts, and for irrigation 

 in others, it is worthy of the landowner's consideration, whether its application 

 would or would not repay the expense. 1 



588. THRASHING. Thrashing machines to be driven by a steam engine are 

 made from four to six horse power ; and the usual proportions are, 



The feeding rollers 35 to 37i revolutions per minute, diameter 3* inches. 



Straw rakes 30 revolutions per minute, diameter 3i feet. 



Drum 300 revolutions per minute, diameter 3| feet. 



The drum has four beaters faced with strong iron plate ; and a cylindric frame 

 with four sets of teeth, five inches long, attached to its circumference, forms the 

 straw rake. 2 



The breadth of the machine, or length of the rollers to receive the feed, is 

 limited by the width to which one feeder can attend in a proper manner, and 

 about from four to five feet is the range: the thickness of the feed cannot be 

 materially altered from that which gives the best effect; and therefore there is 

 only the velocity in which the power can be altered beyond the small change in 

 width. The quantity of wheat thrashed by a machine four feet in breadth varies, 

 according to its quality, from twelve to twenty-four Winchester bushels per hour, 

 and from sixteen to thirty bushels of oats per hour. 



The power required is 100,000 Ibs. raised one foot per minute when for thrash- 

 ing, and 133,000 raised one foot per minute when winnowing machinery is also 



1 By a single engine, (art. 411.) 280,000 cubic feet of water may be raised one foot high by 

 one bushel of coals, and for any other height divide 280,000 by the height in feet. It will require 

 an engine of one horse power to work eleven hours and a half per day, to raise that quantity 

 daily. The expense will be about .8 per annum for each horse power, to return the first cost, 

 and pay for the renewals and repairs of the engine ; the fuel is one bushel of coals per day for 

 each horse power ; and one man and boy will attend an engine of ten or twelve horse power, 

 and also partly to the distribution of the water: the quantity required for an acre would 

 be about 500 cubic feet per day, and therefore an engine of ten horse power would supply 

 560 acres, if it had to be raised ten feet, at a cost which in few cases could exceed ten 

 shillings per acre if continued for six months per year. On proper lands for the purpose, the 

 return would be ample, and a more perfect mode of applying water to land will very probably 

 be discovered. 



2 The straw advances so that each inch receives three strokes of the beaters ; and the stroke 

 should be made with a velocity of about 55 feet per second, or the beater should move at 

 the rate of 3300 feet per minute; these conditions being attended to, the parts may be, in other 

 respects, arranged as the engineer pleases. 



