When sewing machines in factories were powered by central steam engines and transmission belts, they were particularly difficult to operate since, unlike a machine driven by a treadle or electric motor, there were only two speeds: stopped and full on. The operator had to be absolutely sure everything was lined up and ready to go before engaging the clutch that drove the machine. One could, with the clutch disengaged, turn the machine manually, but that was the only alternative to full speed.
I watched that last night before seeing your post. It’s probably weird that it made me think of this song
Here’s a video of restoring and using a 1920’s Merrow overlock-stitch serger. It’s nearly silent and mostly sped-up. It shows taking it apart, cleaning it with kerosene, toothbrush and compressed air, putting it back together, lubricating, threading and using it. It has a rather complicated Victorian-era mechanism, with two rotary cams with complex profiles that guide the threads. Threading is comically complicated.
Merrow had been in business as the prototypical New England knitting mill for 30 years before Joseph M. Merrow invented the overlock-stitch machine in 1868. He continued to run the company for 79 years, until his death in 1947 at age 98. My grandmother and her sisters were his grandnieces. Their trust sold their shares to another branch of the family 20 years ago. Owen and Charlie Merrow, also 4-g’nephews of J.M. Merrow have run the company since then, with great success.