Originally published with the full title: Q. F. F. Q. S. Dissertatio physica de sono quam annuente numine divino jussu magnifici et sapientissimi philosophorum ordinis pro vacante professione physica ad d. 18. febr. a. MDCCXXVII. in auditorio juridico hora 9. publico eruditorum examini subjicit Leonhardus Eulerus A. L. M. respondente adolescente Ernesto Ludovico Burcardo, phil. cand. Basileae, typis E. & J. R. Thurnisiorum, fratrum.
Euler wrote Dissertatio as part of applying to the Physics chair of the University of Basel at the age of 20 (it was customary to present a paper of one's research, to demonstrate that one might be of service to the institution). It was well-received, and was reprinted in 1751 in a collection of papers edited by Albrecht von Haller in Gottingen. (Euler did not get the job and instead left for a position at the Saint Petersburg Academy, where he spent most of his working life). In this essay, Euler first explains his theory of what makes up the atmosphere; the basis of his theory lies in the theory of elasticity of the teacher he had before Johann Bernoulli. He also states without proof a formula for the speed of propagation and derives from it numerical values of the correct order of magnitude for air.