Very rare fourth edition of the commentary of Claude Mydorge (1585-1647) on the Récreations mathématiques by "H. van Etten" (Jean Leurechon). Mydorge corrected the numerous mistakes made by Leurechon in these mathematical diversions and "added several physical experiments... as well as comments that he claimed were intended only for his friends". Several of examples and comments by Mydorge, also appear in the works of his friend Descartes, making it "reasonable to conclude that many of the other mechanical problems discussed by Mydorge in this work were also known to Descartes... and one can easily imagine Descartes as one of the friends participating in the discussions of these problems alluded to in the prefatory remarks" (Hattab).
The "diversions" consist of numerous problems for which a mathematical solution is presented, most of them illustrated by a woodcut. For instance, Mydorge (following Leurechon) informs the reader how to make water in a glass boil without fire, "to make a door open from both sides; ... to build a bridge all round the earth which will not fall when its supports are removed; to keep all the water in the world in the air without a single drop falling to earth". The third chapter, on fireworks, contains even more spectacular problems, such as "if all the gunpowder in the world were put in a globe of glass or paper and set on fire all at once, what would happen? Nothing, since the pressure would be equal in every direction" (Thorndike).
Binding soiled and spine with a few holes; lower part loose in binding. First 50 pages creased; several marks and thumbing throughout. A fair, probably well-used copy. Worldcat (1 copy); for Mydorge: DSB IX, pp. 598-599; Hattab, Descartes on forms and mechanisms, pp. 90-92; Thorndike VII, pp. 593-594.