122 
gradually re-admitted into the receiver, 
in proportion as the-communication is ~ 
restored between the vibrating metal 
and the surrounding atmosphere, the 
stroke of the clapper becomes audible, 
tilt what is called the sound of the bell, 
is as distinctly perceptible as if the 
glass of the receiver had not inter- 
vened. Such glass, in reality, (from 
the contact of air within and without) 
becoming only another medium for the 
transmission of those aerial pulses, which 
are thus demonstrated to be the efficient 
causes of the impression on the audi- 
tory nerve. 
Or Vocat Sounps IN PARTICULAR. 
— But whatever philosophy may be 
able to demonstrate, concerning the 
simplicity and uniformity of the proxi- 
mate cause of sounds, it is sufficiently 
obvious, to the most popular percep- 
tion, that the varieties and modifications 
of those sounds are infinite: nor is it 
less demonstrable, that such varietiés 
depend, in the first instance, upon the 
nature and force of the. remote and 
primarily impelling cause (such for 
example as the quality and momentum 
of the clapper, in the experiment al- 
luded to—as, whether it be wood, lead, 
iron, or other substance, impelled by a 
stronger or a weaker power, &c.)—in the 
second place, on the texture and vibra- 
tory power of the medium. of contact 
and resistance (as the metalic structure, 
for example, the size and composition 
‘of the cup of the bell); and in the third 
place, upon a variety of circumstances 
which affect the diffusion of the original 
vibration ;—and which, in reality, by 
means of sympathetic or secondary im- 
pulses, produce a certain complication 
of vibrations, more or less intricate, 
though manifesting, in many instances, 
an apparently simultaneous effect: such, 
for example, when the receiver was un- 
exhausted, would be the probably sono- 
rous vibration of the glass in the above 
experiment: such are the fibrous vibra- 
tions of the sound boards, &c., of musi- 
cal instruments, which respond to the 
vibrations of the strings and modify the 
respective tones. 
if such be the nature and complica- 
tion of sounds in general, it remains to 
be inquired—What is- the specific na- 
ture of vocal sounds in particular ? 
ways render this experiment, in some de- 
gree, imperfect. But as the sound is al- 
ways less perceptible in proportion as the 
exhaustion of the receiver is comparatively 
complete, the force of the conclusion is not 
invalidated by such imperfection. 
Post-Office Establishment. 
(Mar. I, 
Vocat Sounps are the effects of spe- 
cific vibrations produced, in the first 
instance, by the action and re-action of 
certain organs of the animal throat on 
portions of the atmospheric air, expelled 
by specific impulse from the lungs. 
This is, I believe, the simplest form 
of definition that can be applied to the 
origin and nature of the sounds of voice ; 
and it may therefore answer our pur- 
pose so far as to be initiatory to more 
minute elucidation; but it is, in fact, 
too simple to be instructively accurate 
in the explanation of the complicated 
phenomena to which it refers. The 
tunable voice does not depend upon 
the organs of the throat alone; the 
vibrations, in their passage to the ear, 
are complicated and modified by the more 
minuté vibrations of certain other organs, 
to which, either from necessity or volition, 
the primary impulses are communicated ; 
as, also, by the responses of certain other 
vibratory portions of the animal frame, 
brought into unison (by their tension and 
position) with such impelling organs. 
Orcans or Voice.—From this defi- 
nition, thus explained, two important 
questions properly arise—1l. What are 
the Organs of Impulse and Contact, and 
those of sympathetic Response and Com- 
plication, in the human subject, by which 
vocal sounds are produced? 2, How 
far can man be defective in these, and 
yet be competent to the ordinary functions 
of vitality ? 
The first, if satisfactorily answered, 
will necessarily lead to practical con- 
clusions of considerable importance, 
respecting the means by which the ex- 
ercise of the faculty of speech may be 
' facilitated and improved. The second 
will, at least, enable us to ascertain, 
under what circumstances, the defects 
of utterance are referable to physical 
nature; and how far they are to be 
regarded as beyond the hope of remedy 
from education and exertion. 
It is to the former that we must con- 
fine ourselves in the first instance. The 
latter will come under consideration 
in a more advanced stage of the dis- 
cussion. 
(To be continued ). 
=the 
To the Editor of the Monthly Magazine. 
Sir: 
eae universally-acknowledged con- 
venience, and general approbation 
bestowed upon the economy of the 
Post-office establishment of Great Bri- 
tain, will, doubtless, not only justify the 
insertion, in your Magazine, of the'ac- 
companying 
