Stone sawing: machine, slaves or skilled workers?

"The commissioners first sent to Charleston where there was reportedly a working stone sawing machine. With one horse one man could work four saws. In October 1796 a contractor tried to get it to work, but some brass fittings were wrong, and no one really knew how to run it. So the commissioners ordered their overseer Bennett Mudd, to have "four negro laborers sawing freestone at President's house." They had no particular slaves in mind, any four would do. There are no payrolls in the records showing if any were employed or if they got extra wages like the slave sawyers got."

Quote from Slave Labor in the Capital, page 94

Because I could not find any payrolls nor any other mention of the stone sawing machine, I didn't speculate in the book on who did the bulk of stone sawing. Since the quality of the stone work was so important, I assume that skilled stone cutters or stone carvers prepared the stone before the masons set it, but it seems the initial cutting of the facing stone could be done by machines or unskilled laborers.

Leonard Harbaugh who signed the letter below seemed to have been the contractor most familiar with machines. He sold cranes to the commissioners when he first came to the project in 1792. He came to the city from Baltimore where slaves were used but in payrolls submitted to commissioners when he built the executive office in 1800, he only listed a few slave laborers and no skilled slave workers. Of course, those buildings were made with bricks. Unfortunately his letter gives no hint about whose labor a successful stone cutting machine would replace and we don't know if the commissioners' order for four slaves to saw stone was an effort to replace free laborers or supplement a crew of slaves already sawing stone. By the way, the only workers ever depicted working on the Capitol were a stone cutter and stone sawyer, both depicted as white. You can see that in the background illustration of this blog.