REFERRING to Sir James Jeans's letter in NATURE of Jan. 17, p. 89, I may say that I fully acknowledged in my paper of November 1929 (Mon. Not. Roy. Ast. Soc., 90, p. 20) that Sir James was the first to recognise the principle that the mass M and luminosity L of a star are independent variables as regards steady state considerations. On p. 53 of that same paper (a page of which Jeans himself quotes in another connexion) I made a general reference of obligation to his work. In my last paper (Mon. Not. Roy. Ast. Soc., 91) I build on Jeans's permanent contributions to science in three places, mentioning him by name (pp. 4, 9, 51). I could not, however, adduce any of the specific results of his theory of stellar equilibrium in support of my conclusions, for they are totally different; and I could not contrast his results with mine without venturing to discuss his mathematics.