Architonnerre
The Architonnerre (Architronito) was a steam-powered cannon, a description of which is found in the papers of Leonardo da Vinci dating to the late 15th century, although he attributes its invention to Archimedes in the 3rd century BC. Leonardo's description was hidden amongst his papers until it was rediscovered by Étienne-Jean Delécluze of the French Institute in 1838 and published in the magazine "L'Artiste" in 1841, well after the modern high pressure steam engine had been independently invented. Description of operation. The following is the most likely means of operation from the description given. Leonardo's  own description. Account from the "Nelson Examiner and New Zealand Chronicle", 1842: The Steam-Engine. – M. Delecluze has lately made a discovery among the manuscripts of Leonardo da Vinci, carrying back a knowledge of the steam-engine to at least as far back as the 15th century. He has published in the "Artiste" a notice on the life of Leonardo da Vinci, to which he adds a fac-simile of a page from one of his manuscripts, and on which are five sketches with the pen, representing the details of the apparatus of a steam-gun, with an explanatory note  upon what he designates under the name of the " "Architonnerre"," and of which note the following is a translation : – " Invention of Archimedes. – The "Architonnerre" is a machine of fine copper, which throws balls with a loud report and great force. It is used in the following manner : – One third of this instrument contains a large quantity of charcoal fire. When the water is well heated, a screw at the top of the vessel which contains the water must be made quite tight. On closing the screw above, all the water will escape below, will descend into the heated portion of  the instrument, and be immediately converted into a vapour so abundant and powerful, that it is wonderful to see its fury and hear the noise it produces. This machine will carry a ball of a talent in weight." It is worthy of remark that Leonardo da Vinci – far from claiming the merit of this invention for himself or the men of his time – attributes it to Archimedes. The weight of the cannonball is described as one talent. A Roman talent was , although the amount varied across the ancient world by a few kilos.