ClipArt ETC
"A muffle furnace, employed for annealing, hardening, and tempering." —Encyclopedia Britannica, 1910

Automatic Oil Muffle Furnace

"A muffle furnace, employed for annealing, hardening, and tempering." —Encyclopedia Britannica,…

Seal, with a shovel and hoe on it.

True-temper seal

Seal, with a shovel and hoe on it.