698. Q.—­What is the amount of power necessary to drive cotton mills?

A.—­An indicator or actual horse power will drive 305 hand mule spindles, with proportion of preparing machinery for the same; or 230 self-acting mule spindles with preparation; or 104 throstle spindles with preparation; or 10-1/2 power looms with common sizing.  The throstles referred to are the common throstles spinning 34’s twist for power loom weaving, and the spindles make 4000 turns per minute.  The self-acting mules are Robert’s, about one half spinning 36’s weft, and spindles revolving 4800 turns per minute; and the other half spinning 36’s twist, with the spindles revolving 5200 times per minute.  Half the hand mules were spinning 36’s weft, at 4700 revolutions, and the other half 36’s twist at 5000 revolutions per minute.  The average breadth of the looms was 37 inches, weaving 37 inch cloth, making 123 picks per minute,—­all common calicoes about 60 reed, Stockport count, and 68 picks to the inch.  To take another example in the case of a mill for twisting cotton yarn into thread:—­In this mill there are 27 frames with 96 common throstle spindles in each, making in all 2592 spindles.  The spindles turn 2200 times in a minute; the bobbins are 1-7/8 inches diameter, and the part which holds the thread is 2-3/16 inches long.  In addition to the twisting frames the steam engine works 4 turning lathes, 3 polishing lathes, 2 American machines for turning small bobbins, two circular saws, one of 22 and the other of 14 inches diameter, and 24 bobbin heads or machines for filling the bobbins with finished thread.  The power required to drive the whole of this machinery is 28-1/2 horses.  When all the machinery except the spindles is thrown off, the power required is 21 horses, so that 2592, the total number of spindles, divided by 21, the total power, is the number of twisting spindles worked by each actual horse power.  The number is 122.84.

699. Q.—­What work will be done by a given engine in sawing timber, pressing cotton, blowing furnaces, driving piles, and dredging earth out of rivers?

A.—­A high pressure cylinder 10 inches diameter, 4 feet stroke, making 35 revolutions with steam of 90 to 100 lbs. on the square inch, supplied by three cylindrical boilers 30 inches diameter and 20 feet long, works two vertical saws of 34 inches stroke, which are capable of cutting 30 feet of yellow pine, 18 inches deep, in the minute.  A high pressure cylinder 14 inches diameter and 4 feet stroke, making 60 strokes per minute with steam of 40 lbs. on the square inch, supplied by three cylindrical boilers without flues, 30 inches diameter and 26 feet long, with 32 square feet of grate surface, works four cotton presses geared 6 to 1, with two screws in each, of 7-1/2 inches diameter and 1-5/8 pitch, which presses will screw 1000 bales of cotton in the twelve hours.  Also one high pressure cylinder of 10 inches diameter and 3 feet stroke, making 45 to 60 revolutions per