6th. Do not allow ropes to be struck, or trampled on, when the weight is suspended.
7th. The men should stand as safe as the proper performance of the various duties will permit.
8th. In pulling a rope, the men ought to place themselves in a right line, and haul together. The most advantageous position for pulling is down a slope, or in a descending position.
COMBINATION OF PULLEYS.
A leading block is a fixed pulley, which alters the direction of the power, but does not increase it: Power = Weight. On account of friction the power must exceed the weight a little, in order to raise it.
Vide plate, Mechanics, [Fig. 1.]
A whip is one moveable pulley, which increases the power without altering the direction.
Power = ½ weight (or 2 to 1).—Vide [Fig. 2.]
A whip upon whip will afford the same purchase as a tackle having a single and double block, and with much less friction.