(Continued from page 3 of cover.) 



VOLUME 57. 



1. K.ENT, Norton A. 6u»d Taylor, Lucien B. — The Grid Structure in Eichelon Spectrum 



Lines, pp. 1-18. December, 1921. $.75. 



2. LoTKA, Alfred J. — The General Conditions of Validity of the Principle of Le Gbatelier. 



pp. 19-37. January, 1922. $.75. 



