Early application of kinetic theory of gases to star clusters

This is a case of working by analogy to apply successful work from one field, the kinetic theory of gases, to another field, the distribution of stars in globular clusters. The origin of the analogy lies in Henri Poincaré reading a vague suggestion by Lord Kelvin and recognizing the interest and potential value of this suggestion. The result is the application of mechanics to the dynamics of clusters with very many stars. A good idea, even a very clever good idea, still takes significant work to elaborate in all its implications. Here we see assumptions that lead to partial success in providing a relation between the density of stars in a cluster and the distance from the center. Partial success motivated work using assumptions that were less restrictive. We follow the assumptions and work through 1916, when work paused for many years.