Lifting the stone
Once quarry workers split granite into large blocks in the pit, they used cranes called “guy derricks” to lift the stones destined for the cutting shed and grout piles. About a half dozen derricks operated in and around the quarry pit at any given time. A large permanent derrick served the incline railway that moved blocks down to the cutting shed. Other derricks were temporary and were relocated as work progressed.
HOW A DERRICK WORKED
A guy derrick had a vertical timber mast supported by guy wires radiating out from the top to anchors in the surrounding rock. A wooden boom, angling up from the base of the mast, rose and fell in a vertical plane. When the boom was placed directly over a stone block to be moved, a wire rope with lifting hooks was lowered and attached to the block. The boom and hooks could be independently raised and lowered by wire ropes and pulleys. The boom itself rotated 360 degrees by means of a “bull wheel” at the bottom of the mast. The wire ropes used to move the boom and hook were wrapped around rotating winch drums on a hoist engine near the derrick.
Operating a derrick took teamwork: an engineer ran the hoist, a derrickman at the pit edge oversaw activity and gave hand signals to the engineer, and a rigger in the pit hooked up the heavy loads.
When the quarry opened in the 1890s, derrick winches were powered by “donkey engines,” a type of stationary, coal-fired steam hoist engine. As part of the Grenci & Ellis mid-1920s improvements, at least one derrick was converted to run on an 80-horsepower electric motor.