Smoke jack

Smoke jacks, belong to a family of jacks, which are essentially mechanisms to roast meat over fires, also known roasting jacks. First seen in Switzerland in 1581 AD, whilst earlier sketches have also been found in Italy and as early as 1480 Leonardo Da Vinci famously sketched a design for an airscrew operated smoke-jack. The smoke jack was essentially a set of upturned windmill vanes, placed in the chimney flue, the rising hot air from the fire turned the blades, which was connected to a set of gears to a spindle that rotated a spit which was mounted over the fire to give even roasting. It might be said that smoke jack was one of the earliest inventions converting rising heat energy into mechanical power for a practical use.

Whilst early human turned spits would have been used in the 1st Century, a variety of different ways to mechanically drive the spits appeared over time with the smoke jack being just one; Steam jacks, were driven by steam, bottle jacks or clock jacks,were driven by weights and springs and jacks from the Tudor period even used dogs running on a treadmill as power source. In April 1749 AD, on the banks of the Schukyhkill, Benjamin Franklin held an infamous ‘electric picnic’ in which he tried to rotate his smoke jack using a new power source called electricity. " a turkey was killed for our dinner by electric shock, and roasted by the electrical jack before a fire kindled by the electric bottle’, and the health’s of all his colleagues were ‘drunk in electrified bumpers under the discharge of guns from the electrical battery’.

The modern term for such a rotating spit is a rotisserie.

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