224 CONSTRUCTION OF MACHINES. [Chap. 11.

Make the pulleys 24 inches in diameter, as thick asthe strap is wide, and half an inch higher in the middlethan at the sides, to make the strap keep on; give thema motion of 25 revolutions in a minute, and put on a sheet-iron bucket for every 15 inches; then 125 buckets willpass per minute, which will carry 162 quarts, and hoist300 bushels in an hour, and 3600 bushels in 12 hours.If you wish to hoist faster, make the strap wider, thebuckets larger in proportion, and increase the velocityof the pulley, but not to above 35 revolutions in a minute,nor place more buckets than one for every 12 inches;otherwise, they will not empty well. A strap of 5 inches,with buckets 6 inches long, and of a width and propor-tion suiting the strap, (4i inches wide,) will hold 1,8quarts each; and 35 revolutions of the pulley will pass175 buckets, which will carry 315 quarts in a minute,and 590 bushels in an hour. If the strap be 4 incheswide, and the wooden buckets 5 inches deep, and inproportion to the strap, they will hold ,8 of a quart:then, if there be one for every 15 inches, and the pul-ley makes 27 revolutions in a minute, it will hoist 200bushels in an hour. Where there is a good garner toempty the wheat into, this is the size they are commonlymade, and is sufficient for unloading wagons.

Plate VI., Fig. 6, represents the gudgeon of the lowerpulley; fig. 7, the gudgeon for the shaft on which theupper pulley is fixed. Fix both the pulleys in theirplaces, but not firmly, so that a line, stretched from onepulley to the other, will cross the shafts or gudgeons atright angles. This must always be the case to make thestraps work fairly. Put on the strap with the buckets;draw it tightly, and buckle it; put it in motion, and if itdo not keep fairly on the pulleys, their position may bealtered a little. Observe how much the descending strapswags by the weight of the buckets, and make the caseround it so curved, that the points of their buckets willnot rub in their descent, which will cause them to wearlong and work easily. The side boards need not be madecrooked in dressing out, but may be bent sufficiently bysawing them half way, or two-thirds, through* beginning