﻿CONTENTS OF VOL. XXXVIII. FIFTH SERIES. 



NUMBEE CCXXXIL— SEPTEMBER. 



Dr. J. Webster Low on the Velocity of Sound in Air, Gases, 



and Vapours for Pure Notes of different Pitch 249 



Mr. F. W. Hill on the Hatchet Planimeter 265 



Prof. John Perry on Magnetic Shielding by a Hollow Iron 



Cylinder : Simplest Case 270 



Mr. S. Skinner on the Clark Cell when Producing a Current . . 271 

 Mr. B. Moore on a Eelation between the Surf ace-Tension and 



Osmotic Pressure of Solutions 279 



Lord Eayleigh on the Minimum Current audible in the 



Telephone 285 



Lord Eayleigh : An Attempt at a Quantitative Theory of the 



Telephone 295 



Mr. E. C. C. Baly and Prof. William Eamsay : Experiments 



on the Eelations of Pressure, Volume, and Temperature of 



Earefied Gases. (Plate XL) 301 



Notices respecting New Books : — 



Prof. J. A. Ewing's Steam-Engine and other Heat- 



Engines 327 



Heat of Dissociation according to the Electrochemical Theory, 



by H. Ebert 332 



Alterations of the Electrical Eesistance of Aqueous Solutious 



and of Galvanic Polarization with Pressure, by Bruno 



Piesch 336 



NUMBEE CCXXXIIL— OCTOBEE. 



Mr. F. L. 0. Wadsworth on Fixed- Arm Spectroscopes. 



(Plates VIII.-X.) 337 



Dr. J. McCowan on the Highest Wave of Permanent Type . 351 

 Prof. J. J. Thomson on the Velocity of the Cathode-Eays . . 358 

 Lord Eayleigh on the Amplitude of Aerial Waves which are 



but just Audible 365 



Mr. C. Chree on the Eelation between the Coefficients of 



Pressure in Thermometry 371 



Prof. Henry Crew and Mr. Eobert Tatnall on a New Method 



for Mapping the Spectra of Metals 379 



Mr. L. E. Wilberforce on the Vibrations of a Loaded Spiral 



Spring 386 



Mr. W. C. Dampier Whetham on the Velocities of the Ions 



and the Eelative Ionization-Power of Solvents 392 



Mr. Eollo Appleyard on Dielectrics 396 



Lord Kelvin on the Eesistance of a Fluid to a Plane kept 



moving uniformly in a direction inclined to it at a small 



angle 409 



Eev. J. F. Blake on " Densities in the Earth's Crust " 413 



