‎"EULER, LEONARD. - ON THE ISOCHRONE PROBLEM.‎
‎De innumerabilibus Curuis tautochronis in in Vacuo. (On the innumerable tautochrone curves in a vacuum). (+) Curva Tautochrona in Fluido resistentiam faciente secundum Quadrata cerilitatum. (Tautochrone curves in a fluid making a second resistance pr...‎

‎(Petropoli, St. Petersburg, Typis Academiae, 1735). 4to. No wrappers. In: ""Classes Prima continens Mathematica. Commentarii Academiae Scientiarum Imperialis Petropolitanae"", Tomus IV ad Annum 1729. The whole section of ""Mathematica""offered. Pp 1-118 pp. and 10 engraved plates. Euler's papers: pp. 49-67 a. 2 engraved plates. Pp. 67-89 a. 1 engraved plate. Wide-margined, clean.‎

Reference : 50850

‎Both first editions and some of the earliest mathematical papers by Euler. The first paper is a masterful work, in which Euler first establishes a surprisingly simple geometric condition for tautochronic curves, and then shows how to generate such curves, both analytic and algebraic, starting from the familiar cycloid "" the next paper extends the analysis to a resistive medium where the resistance is in proportion to the square of the speed. - Enestroem E12 and E13.The section (Mathematica) also contains papers by Jacob Hermann, Christopher Maier, G.W. Krafft and Daniel Bernoulli ""Problema astronomicum inneniendi altitudinem poli,...."", pp. 89-94.‎