1874.] On the Pneumatic Action accompanying Articulation. 277 



April 16, 1874. 

 JOSEPH DALTON HOOKER, C.B., President, in the Chair. 



The Presents received were laid on the table, and thanks ordered for 

 them. 



The following Papers were read : 



I. " On the Pneumatic Action which accompanies the Articulation 

 of Sounds by the Human Voice, as exhibited by a Recording 

 Instrument." By W. H. BARLOW, F.R.S., V.P.Inst.C.E. 

 Received February 23, 1874. 



All articulated sounds made by the human voice are accompanied by 

 the expulsion of air from the mouth ; and in a series of articulated 

 sounds the air is ejected in impulses which vary in quantity and pres- 

 sure, and in the degree of suddenness with which they commence and 

 terminate. 



It appeared to me that it would be interesting and probably useful, as 

 tending to elucidate the process and effects of articulation, to construct 

 an instrument which should record these pneumatic actions by diagrams, 

 in a manner analogous to that in which the indicator-diagram of a steam- 

 engine records the action of the engine. 



In considering a suitable form of recording instrument, the conditions 

 to be met were : first, that the pressures and quantities were very vari- 

 able, some of them being extremely small ; and, secondly, that the im- 

 pulses and changes of pressure follow each other occasionally with great 

 rapidity. 



It was therefore necessary that the moving parts should be very light, 

 and that the movement and marking should be accomplished with as little 

 friction as possible. 



The instrument I have constructed consists of a small speaking- 

 trumpet about 4 inches long, having an ordinary mouthpiece connected 

 to a tube | an inch in diameter, the other end of which is widened out 

 so as to form an aperture of 2| inches diameter. 



' This aperture is covered with a membrane of goldbeater's skin or thin 

 gutta percha. 



A spring which carries the marker is made to press against the mem- 

 brane with a slight initial pressure, to prevent as far as practicable the 

 effects of jar and consequent vibratory action. 



A very light arm of aluminium is connected with the spring and holds 

 the marker ; and a continuous strip of paper is made to pass under the 

 marker in the same manner as that employed in telegraphy. 



The marker consists of a small fine sable brush placed in a light tube 

 of glass T \j- of an inch in diameter. The tube is rounded at the lower 

 end, and pierced with a hole about ^ of an inch in diameter. Through 

 this hole the tip of the brush is made to project, and it is fed by colour 



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