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The Analysis of SoundA 
PART I .—The Experimental Analysis of Sound in Air and Water : Some Experiments 
towards a Sound Spectrum. By Guy Barlow, D.Sc, (Wales, Lond., Birm.), 
F.Inst.P., Lecturer in Physics in the University of Birmingham, and H. B. Keene, 
D.Sc. (Birm.), F.Inst.P., Lecturer in Physics in the University of Birmingham. 
PART II .—The Theory of Analysis of an Electric Current by Periodic Interruption . 
By G. Barlow, D.Sc. 
Communicated by Sir Oliver Lodge, F.R.S. 
Received April 6,—Read June 23, 1921. 
PART I.— THE EXPERIMENTAL ANALYSIS OF SOUND IN AIR AND WATER : 
SOME EXPERIMENTS TOWARDS A SOUND SPECTRUM. 
Contents. 
Introduction. 
Apparatus . 
Analysis op a Current. 
(1) Simple Harmonic Current . 
(2) Close Pair of Simple Harmonic Currents—Resolving Power . 
(3) Current Containing Harmonic Series . 
(4) Complex Current . 
Analysis of Sound in Air. 
(«) Magnetophone Receiver . 
(1) Bowed fork, (2) Voice, (3) Organ Pipe, (4) Struck Fork, (5) Diaphragms, (6) Resonators 
(b) Carbon Microphone Receiver . 
(1) Pure Tones .. 
(2) Note from Harmonical . 
(3) Complex Sound .-. 
(4) “ Background ” Experiments . 
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* The experiments described in this paper are published with the permission of the Admiralty. They 
form part of an investigation carried out by the authors in the Physics Department of the University of 
Birmingham during the years 1916 and 1917, at the suggestion of Sir 0. Lodge on behalf of the Board of 
Invention and Research. 
VOL. CCXXII.—A 598. 
u 
[Published February 21, 1922. 
