[1530] 
XXIV.—ON THE ARTICULATION OF THE HUMAN VOICE, 
AS ILLUSTRATED BY THE LOGOGRAPH... By. W... H. 
BARLOW, F.z.8., v.P. INsTITUTE OF Cly1L ENGINEERS. 
[Read March 18, 1878.] 
The instrument called the Logograph was described in a Paper 
read before the Royal Society in April, 1874. 
It is constructed so as to exhibit, diagrammatically, the effects 
of those pneumatic actions which accompany the production of 
articulated sounds. 
It is also capable of showing the presence and duration of 
vowel sounds, or of the vibratory action which accompanies them. 
The pneumatic effect is shown by the movement of the marker 
from its normal position. 
The vowel sound is made apparent by a rapid vibratory 
movement of the marker, occasioned by the vibratory action of 
those organs which operate in the production of sound. 
The instrument consists uf a small speaking-trumpet, about 
four inches long, fastened into a wooden frame which will stand 
on an ordinary table, in a convenient position to be spoken into 
by a person sitting at the table. The mouthpiece of the trumpet 
may be of the ordinary form and material, or made elastic by 
Indian rubber. 
The other end of the trumpet is widened out to an aperture of 
about 21 inches diameter, 
The accompanying figure shows the working part of tue instru- 
ment in plan, 
a, a, », b, is the speaking-trumpet of which 6, b, is the mouth- 
piece. 
Scien. Proc. R.D.S, Vou. 1, Pt. 11. M 
