After drilling and blasting, large stones called mill blocks were brought to the stone cutting shed and sawn into even slabs for sidewalk pavement or smooth building stones. A heavy iron frame held a gang of several sheet metal saws, and an engine powered by compressed air drew the gang back and forth, slowly cutting each block into several thin slabs. A mixture of water and steel filing constantly washed over the block, providing teeth for the smooth-edged saws, and the water drained down the sluiceway between the concrete slabs and into the river. Four gangs of saws worked around the clock in this stone sawmill, and some later machines cut as much as 8 inches per hour in Bedford, Indiana, limestone and from 2 to 3 inches per hour in granite.