XVI. Functions of Positive and Negative Type, and their Connection ivith the Theory 



of Integral Equations. By J. MERCER, B.A., Trinity College, Cambridge. 

 Communicated by Prof. A. R FORSYTE, Sc.D., LL.D., F.R.S. . . page 415 



XVII. The Spectrum of Magnesium Hydride. By A. FOWLER, A.R.C.S., F.K.A.S., 

 Assistant Professor of Physics, Imperial College of Science and Technology, 

 South Kensington. Communicated by Prof. H. L. CALLENDAR, M.A., LL.D., 

 F.R.S. 447 



Index to Volume 479 



