The following are fair approximate rules: Cotton openers. 1 horse-power per 1000 lbs. cotton delivered. Cotton pickers, 3 horse-power per 1000 lbs. cotton delivered. Cotton cards, 1/20 horse-power per lb. cotton delivered per day, and, at 125 revolutions per minute, 0.12-1/2 horse-power. Cotton cards, best practice, 1/40 horse-power per revolution per minute. Railway heads, breakers, 1 horse-power per each 10 yards per minute. Railway heads, finishers, 0.001 horse-power per revolution per minute. Drawing-frames, 0.002 horse-power per revolution per minute. Spindles, 0.005 horsepower per spindle per 1000 revolutions. Damp weather adds 10 or 12 per cent; methods of banding may make equally great variations. Looms require from 0.1 to 0.25 horse-power each. Pickers take 4 to 6 horse-power. Cloth shears from 3 to 4 horsepower.