CONTENTS OF Wm^.— Fourth Series. 



XXXIX. On a Method of detecting the Phases of Vibration in the 

 Air surrounding a Sounding Body, and thereby measuring directly 

 in the vibrating air the lengths of its Waves and exploring the form 

 of its Wave-surface. By Alfred M. Mayer, Ph.D.&c, Professor 

 of Physics in the Stevens Institute of Technology, Hoboken, N. J., 

 United States page 321 



XL. Notes on Bessel's Functions. By the Hon. J. W. Strutt, late 

 Fellow of Trinity College, Cambridge 328 



XLI. Fluorescent Relations of certain solid Plydrocarbons found 

 in Coal-tar and Petroleum Distillates. By Hfis^Ry Mortok-, Ph.D., 

 President of the Stevens Institute of Technology^ U. S 345 



XLII. 0» the Nutrition of Muscular and Pulmonary Tissues in 

 Health and when affected with disease from Phthisis. By William 

 Marcet, M.D., F.R.S 349 



XLIII. On the Connexion of the Second Proposition of the Me- 

 chanical Theory of Heat with Hamilton's Principle. By R. Clausius. 365 



XLIV. On some Points in the Chemistry of Acid-manufacture. 

 By H. A. Smith, Junior Assistant in the Laboratory of Owens Col- 

 lege, Manchester 370 



XLV. On an Experimental Determination of the Relation between 

 the Energy and Apparent Intensity of Sounds of diiFerent Pitch. Bv 

 R. H. M. BosANQUET, M.A., F.C.S., F.R.A.S., Fellow of St. John's 

 College, O.'iford 381 



XLVI. Notices respecting New Books: — The Orbs around us: a 

 Series of familiar Essays on the Moon and Planets, Meteors and 

 Comets, the Sun, and coloured Pairs of Suns. By Richard A. 

 Proctor, B.A. (Camb.). — The Geometry of Conies. — Part L By C. 

 Taylor, M.A., &c. — The Laws of the Winds prevailing in Western 

 Europe.—Part L By W. Clement Ley 388-392 



XLVII. Proceedings of Learned Societies : — 



Royal Society : — The Hon J. W. Strutt on the Reproduction 

 of Diffraction-gratings by means of Photography . 392 



XL VIII. Intelligence and Miscellaneous Articles :— 



Or the Anomalous Dispersion exhibited by certain Substances, 



by M. J. L. Soret .v 395 



On the Measurement of the Intensity of Currents by means of 



the Electrometer, by M. E. Branly 396 



On the Specific Heat of Hydrogenium, by James Dewar,F.R.S.E, 400 



* 



It is requested that all Communications for this Work may be addressed, 

 post-paid, to the Care of Messrs. Taylor and Francis, Printing Ofl&ce, Red 

 Lion Court, Fleet Street, London. 



