Smoke jack

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A smoke-jack is a jack which gets its energy from a column of rising air or smoke. It is typically used to turn a spit in a cooking fire.

A Treatise of Mechanics^[1] describes it this way:

Smoke-jack is an engine used for the same purpose as the common jack; and is so called from its being moved by means of the smoke, or rarefied air, ascending the chimney, and striking against the sails of the horizontal wheel which being inclined to the horizon, is moved about the asix of the wheel AB (plate XXI. fig 1.), together with the pinion C, which carries the wheels D and E; and E carries the chain F, which turns the spit. The wheel AB should be placed in the narrow part of the chimney, where the motion of the smoke is swiftest, and where also the greatest part of it must strike uupon the sails. --The force of this machien depends on the draught of the chimney, and the strength of the fire.

Smoke-jacks are sometimes moved by means of spiral flyers coiling about a vertical axle; and at other times by a vertical wheel with sails like the float-boards of a mill: but the abhove is the more customary construction.

Smoke-jacks were used an example of a technology (together with clockwork and others) that was attainable with contemporary technology by Wilkins in his Mathematical Magick (1648).

Pepys makes mention of a smoke-jack in his diary ^[2] entry for 1660-11-12:

The last night I should have mentioned how my wife and I were troubled all night with the sound of drums in our ears, which in the morning we found to be Mr. Davys’s jack, but not knowing the cause of its going all night, I understand to-day that they have had a great feast to-day.

[edit] References

1. ^ A Treatise of Mechanics: Theoretical, Practical, and Descriptive (1826) By Olinthus Gregory
2. ^ Monday 12 November 1660 (Pepys' Diary)