In 1634 Descartes wrote to Mersenne :

let me tell you about an experiment that was published not long ago in Leurechon’s Mathematical Games. It involves a large cannon placed on flat ground, pointing straight up at the sky, and fired.

Is Leurechon’s original description of this experiment still available to us?


1 Answer 1


Yes, it is.

See Jean Leurechon (1591–1670), jesuit, professor of Mathematics from 1614 to 1627 and then professor of theology.

He published : Récréation mathématique: Composée de plusieurs problèmes plaisants et facétieux : En feict d'Arithméticque, Géométrie, Méchanicque, Opticque, et autres parties de ces belles sciences, Pont-à-Mousson, 1624 (reprinted 1626).

See : 86. Probleme des Canons, page 108&on; page 110 :

A ce compte, dira quelqu'un, le Canon pointé droict au zenith deburoit tirer pòus fort, qu'un toute autre posture. [...] Mais pour moy qui trouve de la difficulté à croire cette experience, ...

The English translation was published in 1633 under the name of Laurechon's student : Hendrick Van Etten.

Descartes reference is in his letter to Mersenne, dated April 1634.

Descartes discuss the movement of Earth, with reference to Galileo's condemnation.

The issue is about possible experimental verification of Earth's movement; specifically about the fall on ground of a stone thrown vertically. Descartes asks to Mersenne about "an experiment that was published not long ago in Leurechon’s book"

The author of the book says that the experiment has already been performed many times, and the cannon-ball didn’t once fall back to the ground. Many might think this quite incredible, but I don’t judge it to be impossible, and I think it’s well worth looking into.


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