A History of the Growth of the Steam-Engine

by Robert Henry Thurston

The first mine-engine, erected in 1712 at Griff, was 22 inches in diameter, and the second and third engines were of similar size. That erected at Ansthorpe was 23 inches in diameter of cylinder, and it was a long time before much larger engines were constructed. Smeaton and others finally made them as large as 6 feet in diameter.

In calculating the lifting-power of his engines, Newcomen’s method was “to square the diameter of the cylinder in inches, and, cutting off the last figure, he called it ‘long hundredweights;’ then writing a cipher on the right hand, he called the number on that side ‘odd pounds;’ this he reckoned tolerably exact at a mean, or rather when the barometer was above 30 inches, and the air heavy.” In allowing for frictional and other losses, he deducted from one-fourth to one-third. Desaguliers found the rule quite exact. The usual mean pressure resisting the motion of the piston averaged, in the best engines, about 8 pounds per square inch of its area. The speed of the piston was from 150 to 175 feet per minute. The temperature of the hot-well was from 145° to 175° Fahr.

Smeaton made a number of test-trials of Newcomen engines to determine their “duty”—i. e., to ascertain the expenditure of fuel required to raise a definite quantity of water to a stated height. He found an engine 10 inches in diameter of cylinder, and of 3 feet stroke, could do work equal to raising 2,919,017 pounds of water one foot high, with a bushel of coals weighing 84 pounds.

One of Smeaton’s larger engines, erected at Long Benton, was 52 inches in diameter of cylinder and of 7 feet stroke of piston, and made 12 strokes per minute. Its load was equal to 71∕2 pounds per square inch of piston-area, and its effective capacity about 40 horse-power. Its duty was 91∕2 millions of pounds raised one foot high per bushel of coals. Its boiler evaporated 7.88 pounds of water per pound of fuel consumed. It had 35 square feet of grate-surface and 142 square feet of heating-surface beneath the boilers, and 317 square feet in the flues—a total of 459 square feet. The moving parts of this engine weighed 81∕2 tons.

Smeaton erected one of these engines at the Chasewater mine, in Cornwall, in 1775, which was of very considerable size. It was 6 feet in diameter of steam-cylinder, and had a maximum stroke of piston of 91∕2 feet. It usually worked 9 feet. The pumps were in three lifts of about 100 feet each, and were 163∕4 inches in diameter. Nine strokes were made per minute. This engine replaced two others, of 64 and of 62 inches diameter of cylinder respectively, and both of 6 feet stroke. One engine at the lower lift supplied the second, which was set above it. The lower one had pumps 181∕2 inches in diameter, and raised the water 144 feet; the upper engine raised the water 156 feet, by pumps 171∕2 inches in diameter. The later engine replacing them exerted 761∕2 horse-power. There were three boilers, each 15 feet in diameter, and having each 23 square feet of grate-surface. The chimney was 22 feet high. The great beam, or “lever,” of this engine was built up of 20 beams of fir in two sets, placed side by side, and ten deep, strongly bolted together. It was over 6 feet deep at the middle and 5 feet at the ends, and was 2 feet thick. The “main centres,” or journals, on which it vibrated were 81∕2 inches in diameter and 81∕2 inches long. The cylinder weighed 61∕2 tons, and was paid for at the rate of 28 shillings per hundredweight.

By the end of the eighteenth century, therefore, the engine of Newcomen, perfected by the ingenuity of Potter and of Beighton, and by the systematic study and experimental research of Smeaton, had become a well-established form of steam-engine, and its application to raising water had become general. The coal-mines of Coventry and of Newcastle had adopted this method of drainage; and the tin and the copper mines of Cornwall had been deepened, using, for drainage, engines of the largest size.

Some engines had been set up in and about London, the scene of Worcester’s struggles and disappointments, where they were used to supply water to large houses. Others were in use in other large cities of England, where water-works had been erected.

Some engines had also been erected to drive mills indirectly by raising water to turn water-wheels. This is said by Farey to have been first practised in 1752, at a mill near Bristol, and became common during the next quarter of a century. Many engines had been built in England and sent across the channel, to be applied to the drainage of mines on the Continent. Belidor[32] stated that the manufacture of these “fire-engines” was exclusively confined to England; and this remained true many years after his time. When used for the drainage of mines, the engine usually worked the ordinary lift or bucket pump; when employed for water-supply to cities, the force or plunger pump was often employed, the engine being placed below the level of the reservoir. Dr. Rees states that this engine was in common use among the collieries of England as early as 1725.

The Edmonstone colliery was licensed, in 1725, to erect an engine, not to exceed 28 inches diameter of cylinder and 9 feet stroke of piston, paying a royalty of £80 per annum for eight years. This engine was built in Scotland, by workmen sent from England, and cost about £1,200. Its “great cost” is attributed to an extensive use of brass. The workmen were paid their expenses and 15s. per week as wages. The builders were John and Abraham Potter, of Durham. An engine built in 1775, having a steam-cylinder 48 inches in diameter and of 7 feet stroke, cost about £2,000.

Smeaton found 57 engines at work near Newcastle in 1767, ranging in size from 28 to 75 inches in diameter of cylinder, and of, collectively, about 1,200 horse-power. Fifteen of these engines gave an average of 98 square inches of piston to the horse-power, and the average duty was 5,590,000 pounds raised 1 foot high by 1 bushel (84 pounds) of coal. The highest duty noted was 7.44 millions; the lowest was 3.22 millions. The most efficient engine had a steam-cylinder 42 inches in diameter; the load was equivalent to 91∕4 pounds per square inch of piston-area, and the horse-power developed was calculated to be 16.7.