From Benjamin Franklin to the Marquis Turgot, 1 May 1781
To the Marquis Turgot6
AL (draft): University of Pennsylvania Library; copy: Library of Congress
Passy May 1. 1781
Sir,
I did intend when in London to have published a Pamphlet, describing the new Stove you mention, and for that purpose had a Plate engrav’d of which I send you an Impression.7 But I have since been too much engag’d in Affairs to execute that Intention. Its Principle is that of a Syphon revers’d, operating on Air in a manner somewhat similar to the Operation of the common Syphon on Water. The Funnel of the Chimney is the longer Leg, the Vase is the shorter. And As in the common Syphon, the Weight of Water in the longer Leg is greater than that in the shorter Leg, and thus in Descending permits the Water in the shorter Leg to rise, by the Pressure of the Atmosphere: So in this Aerial Syphon, the Levity of the Air in the longer Leg being greater than that in the Shorter, it rises & permits the Pressure of the Atmosphere to force that in the shorter to descend. This causes the Smoke to descend also, & in passing through burning Coals, it is kindled into Flame, thereby heating more the Passages in the Iron Box whereon the Vase which contains the Coals is plac’d and retarding at the same time the Consumption of the Coals. On the left hand of the Engraving you see the Machine put together and plac’d in a Niche built for it in a common Chimney. On the right hand the Parts (except the Vase) are shown separately. If you should desire a more particular Explanation, I will give it to you vivâ voce, whenever you please. I think with you that it is capable of being us’d to Advantage in our Kitchens, if one could overcome the Repugnance of Cooks to the using of new Instruments & new Methods. With great Respect, I have the honour to be Sir,8
M. le Marquis de Turgot
6. In answer to his of April 25: XXXIV, 574.
7. This was the same engraving that BF had sent to Morand in 1778: XXVII, 507n. He had it engraved in 1773 when he intended, as he says here, to publish a description of it. BF first mentioned the stove in a letter to Dubourg of Jan. 22, 1773, characterizing it as little more than a curiosity since it required a degree of fussing that ordinary servants could not be expected to perform. Dubourg published this section of BF’s letter in Œuvres de M. Franklin; this explains why the two recent inquiries (this one of Turgot’s, and the one summarized in XXXIV, 69) both mention the problem of servants. BF sent Dubourg the first known copy of the engraving; see XX, xvii–xviii, 25–6, and especially p. 251 and facing (where it is reproduced).
8. On Sept. 20 BF purchased another kind of stove from the inventor, M. Nivert. This was one of the “Nouveaux fourneaux économiques et portatifs,” a portable cooking stove which had been described in the Gaz. de Santé of Oct. 1, 1780. Nivert had this article reprinted as a broadside on March 13, 1781, and furnished BF with a copy, as well as his two-page set of printed instructions. The stove had features of both a Dutch oven and a steam cooker; as many as three cooking vessels (of glass, porcelain, pottery, or crystal) could be used simultaneously. The two broadsides mentioned above, as well as Nivert’s receipt for 60 l.t. 15 s., are at the APS.