Tuesday, 22 November 2011

A View up the President's Chimney

A few weeks ago I was at Mt. Vernon in Virginia, the home of George Washington, where I spoke at a really excellent conference on the subject of Dining with the Washingtons. The curatorial staff were kind enough to give me a private tour of the house and its associated buildings. I found the kitchen rooms particularly interesting and was allowed to explore the inside of the flu belonging to the large fireplace where Mrs Washington's enslaved kitchen staff roasted George's dinner. I was interested to see that the smoke jack mechanism which powered the spits was still in situ. Although I have seen many of these mechanisms in the UK, this was the first American one dating from the eighteenth century that I have ever had the opportunity to inspect. 

Unlike most of the surviving British examples, where the gearing comes out onto the front of the chimney breast, the Mt Vernon smoke jack is housed entirely in the flu with the jack chains which turn the spits hanging directly down the chimney. It is of a type that once must have been common in Britain before roasting began to be more commonly carried out in front of raised coal burning ranges rather than before a down hearths fuelled with wood. All photographs courtesy of Mt. Vernon.

The inglenook in the Mt Vernon kitchen with a pastry oven to the right
Looking vertically up the Mt Vernon kitchen flu, the smoke jack turbine and its gearbox can be clearly seen. The rectangular  sheet of iron is the cover for the gearbox. These boxes were usually filled with oil in which the worm and worm wheel turned. The oil was changed once a year.
There are two metal pulleys running two jack chains, so two horizontal 
spits could be rotated at the same time.

As far as I know this is the earliest English depiction of a smoke jack. From John Wilkins Mathematical Magick. (London: 1648).  However, this movement includes a contrate wheel and lantern pinion rather than the worm and wheel in the Mt. Vernon smoke jack.
The Italians were the first to document smoke jacks. Leonardo de Vinci illustrated one in about 1487. The image above was published in Scappi's Opera. (Venezia: 1570). That ice cream must have melted very quickly with all the heat.

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