Leonhard Euler, most sagacious mathematician, to the author
This work is a portion of a letter written by Euler to Johann Bernoulli (dated 18 October 1740), and appears as the frontispiece to Bernoulli's Hydraulica. An English translation is available as part of Carmody and Kobus's combined English translation of Daniel Bernoulli's Hydrodynamica and Johann Bernoulli's Hydraulica. A translation of the next portion of the letter is available in Hunter Rouse's preface to the work (p. X).
Original Source Citation
Lausanne & Geneva: Marcum-Michaelem Bousquet, Volume 4, pp. 389.
Opera Omnia Citation
Series 2, Volume 12, pp.1-1.