|Title page of German physicist Rudolf Clausius' 1857 "On the Nature of the Motion which we call Heat" which launched both kinetic theory and statistical mechanics.|
Dining room anecdote
See main: Thermodynamics anecdotesIn this paper, Clausius supposedly deduced the average speed of particles to be moving in the neighborhood of 300 to 1,000 meters per second (modern values often cite 500-meters per second or 1,200-mph). This calculation drew a quick response from Dutch meteorologist Christoph Ballot who argued that if he were seated in a long dining room and the butler brought in dinner, it would be some moments before the smell of the food would reach his nose.  A response to this objection by Clausius resulted in the development of the concept of themean free path. 
In 1856, a year prior to Clausius' paper, German chemist and physicist August Kronig published his "A General Theory of Gases", which outlined a simple gas-kinetic model that considered the translational motion of the particles.  This paper seems to have spurred Clausius into his publication, as Clausius comments that in Kronig's paper he recognizes some of his own views.
In 1860, Irish physicist James Maxwell published his “Illustrations on the Dynamical Theory of Gases”, an elaboration of Clausius’ paper, taking into account not only the average speeds of particles, but a graph of the distribution of speeds of the particles at any given temperature. In 1868, Austrian physicist Ludwig Boltzmann published a more convincing physical explanation of the formula Maxwell had derived. Boltzmann would go on to initiate statistical mechanics, by furthering his work in this same area .
1. Clausius, Rudolf. (1857), "Über die Art der Bewegung, die wir Wärme nennen", Annalen der Physik, 100:353–379; trans. “On the Nature of the Motion which we call Heat” (PDF), Philosophical Magazine (1857), 14:108-27.
2. Lindley, David. (2001). Boltzmann’s Atom: the Great Debate that Launched a Revolution in Physics (pgs. 17-18). The Free Press.
3. Krönig, August. (1856), "Grundzüge einer Theorie der Gase" (A General Theory of Gases), Annalen der Physik, 99: 315-322.
4. Lindley, David. (2001). Boltzmann's Atom: the Great Debate that Launched a Revolution in Physics (pgs. 24-25). The Free Press.
5. Buys-Ballot, Christoph. (1858). “Ueber die Art von Bewegung welche wir Warme und Elektrizitat nennen” (“On the Kind of Motion we Call Heat and Electricity”), Ann. Phys. 103: 240.
6. Clausius, Rudolf. (1859) . “On the Mean length of the Paths described by the Separate Molecules of Gaseous Bodies on the Occurrence of the Molecular Motion: together with some other remarks upon the mechanical theory of heat”, Phil. Mag. 17:81-91.
● Harmon, Joseph E. and Gross, Alan G. (2007). The Scientific literature: a Guided Tour (The Nature of Heat, pgs. 108-10). University of Chicago Press.