“I have thus shown in what manner one can imagine that light propagates successively by spherical waves.”

“About 1678, Huygens constructed a cylinder and fitted it with a piston, with a weight of some 1600 lbs., which he forced up for five or six feet by means of a thimbleful of powder, in a gentle manner, and the return of which to the bottom of the cylinder lifted ‘into the air’ four or five boys who held on to the rope. Huygens appears to have rested satisfied with exhibiting this engine, and registering it in the Academy, but Papin, who had brought a copy of his treatise to Boyle, was employed by the latter, and for about three years was continually engaged with air-pumps and his private invention of the ‘digester’. Papin oscillated between London and Paris for a few years, and twice held an appointment under the Royal Society, introducing many remarkable inventions to their notice. About 1687, he was appointed Professor of Mathematics, at Marburg, and appears to have taken up the gunpowder and air-engine, which he had become familiar with whilst assistant to Huygens. Papin published his account of his experiments in the Acta Eruditorum, and in that periodical for 1690 appears the description of his famous memoir in which the suggestion of a vacuum produced under a piston by the condensation of steam was first suggested. Huygens himself acknowledged the ‘inconveniences’ of attempting to produce a series of vacua by exploding gunpowder, and as Papin says, ‘he, therefore, endeavored to attain the same end in another way’, and he ‘at once saw’ (after making some experiments) that ‘machines could be constructed in which water, by the help of a moderate heat, and at little cost, might produce that perfect vacuum which could by no means be obtained by the aid of gunpowder’. Papin proceeded to describe the construction which, amongst many he had devised, seemed ‘most suitable’, and he concluded by proposing to apply the power thus obtained for drawing water or ore from mines, for discharging iron bullets to a great distance, for propelling ships against the wind, and for a number of other purposes; but—and this is an important point in apportioning him his place on the roll—he does not appear to have constructed any successful engines, although Figuier gives an imaginative picture of the destruction of Papin's steamboat in 1695 by the bargemen of the Seine. Saussure and Pean give the credit of this act to the boatmen on the borders of the Hessian territory.”

— Anon (1881), “The History of the Steam Engine: Overview of Galloway’s The Steam Engine and its Inventors” [6]

“About this time Huygens had as his assistant Denis Papin, a Frenchman who later worked with Boyle in England. With Papin, Huygens in 1673 experimented on gunpowder as a source of mechanical energy. There is a possibility that Huygens had considered some kind of atmospheric engine as early as 1660 when he talked with Pascal about the ‘force of water rarefied in cannons’. In these experiments of 1673, we can see the forerunner of Papin's atmospheric engine, which did in fact employ steam in place of gunpowder. Papin was later, through the interest of the Landgrave of Hesse, appointed professor at the university of Marbourg and it was here that he developed the atmospheric engine which gave Newcomen his clue. In exchange for Papin, as one might say, Oldenburg sent over to Huygens the wealthy young amateur Walter von Tschirnhaus, a friend of Spinoza and Leibnitz. He belonged to a class which had early supported the new scientific.”

— Arthur Bell (1947), Christiaan Huygens [11]

“The famous controversy between Newton’s emission theory and Huygens’ wave theory of light is also a phantom problem of science.”

— Max Planck (c.1947), Scientific Autobiography (pg. 59)

“Huygens calculated that a single pound of gunpowder could raise 3,000 pounds a distance of thirty feet. In a 1673 experiment he managed to lift a weight using a small cylinder.”

— Jack Kelly (2009), Gunpowder (pg. 118)

“Saw Chapelain, Conrart, Roberval. Didn’t find Carcavy. The duc de Roannez came to see me, and Pascal later. Talked about the force of steam in their cannon and about flying. I showed them my telescopes.”

— Christiaan Huygens (1660), Journal Entry, Dec 13 [12]

“In all of [Descartes'] physics, I find almost nothing to which I can subscribe as being correct.”

— Christiaan Huygens (c.1660) (Ѻ)