Physical Processes in Gaseous Nebulae. IV. The Mechanistic and Equilibrium Treatment of Nebular Statistics.

The statistical equilibrium of nebulae has been discussed in the past from two points of view. H. H. Plaskett employed a mechanistic argument, where the captures in a given level are subdivided according to the probabifity of transitions to lower levels and are followed through successive transitions down to the ground level. Carroll criticized Plaskett's treatment and developed equations on an equilibrium argument. We have shown that the two points of view, when properly applied, lead to the same result; and we have derived the necessary equations, which will lead to a deterniina- tion of electron temperature