A Hastener was a half-shell device open at the front. At the top of the device inside, you’d hang a piece of meat on a spit. The meat would hang down vertically, and be rotated automatically by a clockwork mechanism . You’d set the device on the floor at the front of the hearth, with the open half facing the hearth and the fire. The inside of the shell would act as a reflector for the heat from the fire. The bottom of the shell would catch the fat as it dripped. The back has a door in it, that you can open to check on the progress of the meat, without having to turn the whole, very hot device around.
Clockwork Spits were used for hanging meat to cook vertically from in front of or by a fire.
The spit would be on a chain, coming down out of a cylinder. You’d wind the clockwork mechanism inside with a key. The mechanism would turn and rotate the meat hanging down from it.
Between the clockwork mechanism and the actual spit below it would often be a spoked wheel on which you could put pieces of fat that would drip down onto the meat to baste it.
Some people had horizontal wall brackets mounted by a fireplace, that would swing out and back in place when not in use; you’d hang a clockwork spit off of them.