High-quality black-and-white photographs of large old machines and tools

[old kodger]

It looks like he is blowing compressed air at it. Does anybody know why?

I'm not sure in this instant, but I do know that to make toughened glass they heat it and quickly cool the surface which makes the outside shrink causing a tension In the plate, which is why, if you try to cut toughened glass it will shatter because you've released the tension in a local area.