CONTENTS (continued). 



February 20, 1879. 



PAGE 



I. On Electrical Insulation in High Vacua. By William Crookes, F.R.S. 347 



II. On the Keversal of the Lines of Metallic Yapours. No. IV. By G-. D. 

 Liyeing, M.A., Professor of Chemistry, and J. Dewar, M.A., F.E.S. , 

 Jacksonian Professor, University of Cambridge . . . . 352 



February 27, 1879. 



I. Studies in Acoustics. I. On the Synthetic Examination of Vowel Sounds. 



By William Henry Preece and Augustus Stroh. Plates 6, 7 . . 358 



II. On the Reversal of the Lines of Metallic Vapours. No. V. By Gr. D. 

 Ll vein G, M.A., Professor of Chemistry, and J. Dewar, M.A., F.R.S., 

 Jacksonian Professor, University of Cambridge ..... 367 



List of Presents . . . 372 



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