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Full text of "The dentaphone : a new scientific invention, which enables the deaf to hear by the sound-vibrations conveyed through the medium of the teeth, and the deaf and dumb to hear and learn to speak"

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Scientific Invention, 

£he Deaf to (Hear 


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The Deaf#Dumb to Hear#Learn to Speak 










We submit in this Pamphlet a short Description of the Denta- 
phone, and its Mode of Action, together with a Sketch of the 
Mechanism of the Healthy Ear. We have added, besides, Press 
Notices, selected from leading Secular and Religious News- 
papers in various Parts of the Country, with Testimonials 
from Professional Men of High Standing in their several Pro- 
fessions and in the Community at large. 

A careful Perusal of the following Pages will give the 
Reader some Conception of the Great Merits of this Remark- 
able Invention, though, to realize fully its Immense Impor- 
tance to a 'Large Class of Sufferers, it must he seen in Opera- 
tion, enabling the Deaf to Hear Distinctly, aud the Deaf and 
Dumb to Hear and Learn Spoken Language* 


Ordinary Conversational Size, - - - $8.00 
Large Size, for Operas, Concerts, Etc., - 12.00 

The Conversational Dentaphone, which is the one commonly used, in Size and Shape 
very much resembles an Old-fashioned Silver Watch. It weighs less than Two Ounces, 
and when not in use is very conveniently carried in an ordinary Watch-pocket. 

The Dentaphone of either Size is sent by mail or Express, Prepaid, 
to any part of the United States or Canada, on Receipt of Price. 

Parties who desire to Order by Express, C. O. I>., are required to 
pay all Express Charges. 

Owing to its small Size and Weight, the Dentaphone is most con- 
veniently sent by Mail. 

Send Money by Post-office Order, Registered Letter, Draft, or 
Express. Give yonr Name and Post-office Address in Full. 

-A. d. dross 


2S7 Vine Street, CINCINNATI, O. 



A New Scientific Invention, 








287 Vine Street, Cincinnati, O. 


Copyrighted, 1879, °y The American Dentaphone Company. 



For many years various inventors have been engaged in devising some 
means whereby the deaf could be relieved from their infirmity, and enabled 
to hear spoken words and readily carry on conversation with those around 
them.. One device has succeeded another, each only leaving the sufferer 
more disappointed than the last, until finally he has given up all hopes of 
relief, or, as in certain cases, is compelled to fall back on the use of the 
clumsy, old-fashioned ear-trumpet. In a large number of instances, how- 
ever, even the ear-trumpet could not be used, as the defect in the hearing 
was of such a nature that the sound vibrations, however intensified by an 
ear-trumpet or other device, could not be transmitted through the ear to the 
nerves of hearing. Under these circumstances no advance seemed possible 
in the way of enabling the deaf to hear, and those who best understood 
the difficulties to be overcome could give no hopes of success. 

The wonderful accuracy with which the Phonograph and the Telephone 
registered and reproduced the human voice, taken in connection with the 
fact that the nerves of hearing could be reached directly through the teeth 
and bones of the face and head, led to the conclusion that if some instru- 
ment could be devised sensitive enough to gather up the delicate sound- 
vibrations that make up spoken words, and convey them to the teeth, this 
problem of enabling the deaf to hear would be solved. The DentaphOne 
is the final result of a long series of experiments in this direction; and 

that it is a complete success is at once evident, not only to the deaf using 
it, but also to any other person who will, for the time, render himself deaf 
by muffling the head, or closing the ears and standing at a long distance 
from the speaker. 


The Dentaphone, like other important inventions, is comparatively simple 
in its details, though yielding such remarkable results. In size and shape 
the instrument very much resembles an old-fashioned silver watch, and 
weighs but little over an ounce and a half. It consists, in brief, of a 
chambered box, in which is secured an exceedingly delicate, easily vibrating 
diaphragm. The size and shape of the chambers, the material and con- 
struction of the diaphragm, etc., have been determined by experiment, as, 
indeed, has every detail pertaining to the instrument. In the diaphragm 
and chambers consist the essential parts of the Dentaphone, all other points 
being of minor importance. 

Sounds caused by the human voice, musical instruments, etc., etc., im- 
pinge on the delicate diaphragm of the Dentaphone and throw it into vibra- 
tion, exactly as the same sounds would cause the drum of the healthy ear 
to vibrate. These vibrations of the diaphragm are increased in intensity by 
the peculiar construction of the chambers of the instrument, and are then 
conveyed to the mouth-piece in contact with the teeth. From the upper 
teeth the vibrations are conveyed through the bony framework of the head 
to the auditory nerve inclosed in the inner ear, thus producing the sensation 
of hearing. 

Just as the Phonograph or Telephone records or transmits every sound 
with the utmost accuracy, so the Dentaphone receives and transmits every 
modulation of the speaker's voice, until it is heard as clearly as by the 
ordinary healthy ear. 


In order to thoroughly understand the working of the Dentaphone, it is 
desirable to give a short sketch of the healthy ear, and the ordinary pro- 
cess of hearing. The perfect ear consists of three chambers or divisions, 
called respectively the outer, middle and inner ear, and marked A, B and 

Sectional Diagram of the Three Chambers of the Ear. 

C in the accompanying diagram. The outer ear is about an inch and a 
quarter long, and communicates directly with the outside air. Between the 
outer and the middle ear is a thin partition or membrane called the ear- 
drum (E). To the inside of the ear-drum is attached the first of a series 
or chain of small bones (F) which run across the middle ear or chamber, 
from the ear-drum to a similar thin membrane which separates the middle 

from the inner ear. The outer and middle divisions or chambers of the 
ear contain air, and the middle ear. communicates with the upper and back 
part of the throat by a small tube marked D in the diagram. The inner 
chamber of the ear, which is firmly imbedded in the bony structure of the 
skull, contains a thin, watery liquid in which are floating the fine ends or 
filaments of the auditory nerve, which is the nerve of hearing. Now, in 
the process of hearing, when a sound is made, the vibrations of the out- 
side air strike against the ear-drum and set it in vibration. This vibration 
is communicated to the chain of small bones in the middle ear and from 
them to the inner membrane separating the middle from the inner ear. 
The vibrations of this membrane, are imparted to the liquid of the inner ear, 
and the vibrations of this liquid acting on the fine extremities of the audi- 
tory nerve floating in it, constitute hearing. ■ From this it will be seen that 
hearing is nothing more nor less than the vibrations of the outside air, which 
are communicated to the outer and inner ear, and finally to the auditory 

Now it is evident that if any of these parts described are diseased, the 
sound-vibrations will be conveyed imperfectly or not at all, and deafness is 
the result. In certain cases, the use of an ear-trumpet, by increasing the 
sound-vibrations, may enable them to be conveyed with more force through 
the ear; but it is also clear that, in other cases, the membranes, bones, etc., 
of the ear may be so disordered as to render them incapable of conveying 
any sound-vibrations. For instance, the outer chamber may be closed up; 
or the ear-drum so thickened that it will not vibrate; or it may be entirely 
destroyed by disease; or the chain of bones may be diseased or removed; or 
the tube leading to the throat may be closed; in all these cases constituting 
forms of disease in which the hearing may be much impaired or entirely 

The success of the Dentaphone in all these and similar cases depends on 
the fact that the sound-vibrations, instead of being conveyed by the diseased 
ear to the liquid in the inner chamber containing the auditory nerves, are 
conveyed directly from the teeth through the bones of the head. As the in- 

strument gathers up the sound-vibrations on its delicate diaphragm and con- 
veys them to the teeth, and, as there is a solid bony connection between the 
teeth and the inner ear, all sounds, including spoken words, are conveyed to 
the auditory nerve and heard just as clearly as by the healthy ear. As the 
ear has nothing to do with the process, it is plain that the degree of deaf- 
ness has little effect on the readiness with which every thing is heard. 


The results of the experiments quoted in another part of this pamphlet 
from the New York Herald, Cincinnati Enquirer, etc., show that the Denta- 
phone will be extensively used in educating the deaf and dumb to under- 
stand spoken language. By beginning with simple words, and in every 
case encouraging the deaf and dumb person to repeat them, it is surprising 
what rapid progress is made in a few days' practice. One of the most in- 
telligent of the pupils of the Franklin Street School, on hearing the word 
'George pronounced through the Dentaphone, for the first time, attempted to 
repeat it, and gave with clearness and distinctness the sound Aurge, 
being exactly the same as George with the G imperfectly given. When we 
reflect that in this case, the sounds had never been heard before, and the 
vocal organs had never been trained, the success is extremely surprising. 
Any person who has noticed the facility with which the deaf and dumb learn 
to understand what is said, by merely watching the lips of the speaker, can 
readily comprehend the wonderful results obtained by the use of the 

In a great many instances children, whose hearing is defective, hear words 
imperfectly, consequently, do not learn to speak, and are mistakably supposed 
to be deaf and dumb. In such cases the Dentaphone is successfully used, 
and the greater distinctness with which every thing is heard, enables the 
child to readily understand and use spoken language. 



Though an excellent substitute for an ear-trumpet, and one which will 
inevitably displace every form of the latter very inconvenient instrument, the 
Dentaphone is a great deal more than this. The Dentaphone not merely 
receives the sounds spoken into it, but it gathers on its sensitive dia- 
phragm and transmits to the auditory nerves sounds coming from a dis- 
tance, such as ordinary conversation, the voice of public speakers, the 
music of concerts, operas, etc., etc., and, in short, is a complete substitute 
for the healthy ear. 

Indeed, no one familiar with the construction of the ear can fail to be 
Struck by the close likeness which the Dentaphone, with its sensitive dia- 
phragm, chambers and mouth-piece, bears to the outer and middle ear, the 
ear-drum and its attached chain of bones. In this, as elsewhere in our 
most important discoveries, we often come at last to find that we have but 
been imitating the methods of Nature. 


Many persons fear that the Dentaphone can not be used with artificial 
teeth. This mistake arises from a misconception of the manner in which 
the sounds are conveyed from the teeth to the ear. With this process the 
nerves of the teeth have nothing whatever to do, the vibrations being trans- 
mitted entirely through the bony framework of the face and head; and 
hence, so long as artificial teeth are properly in their place, they conduct the 
sounds just as well as would the natural teeth. 


In using the Dentaphone the deaf person simply holds the instrument in 
the hand, and it is of no importance whether it is held close to the mouth 
or with the hand resting on the knee, or in any other convenient position, 
as the conductor connecting the mouth-piece may be so lengthened or 
shortened as to allow the instrument to be held wherever it is most com- 
fortable for the person using it. Thu<5 it will be seen that, in addition to 
its small size, which makes it convenient to carry in an ordinary watch- 
pocket, the ease and comfort with which the Dentaphone is used render it 
entirely unobjectionable to many persons who would be too sensitive to 
carry an ordinary ear-trumpet. 


We insert here a few testimonials which have been selected mainly on 
account of the high social and professional standing of the gentlemen giving 
them. These, with the newspaper extracts which follow them, will, we believe, 
enable the Intelligent reader to form a just estimate of the great merits of 
this new scientific discovery. 

From Rev. ISAAC ERRETT, Editor of The Christian Standard. 

Office of the Christian Standard, October 4th, 1879. 
Allow me to say that the experiments and tests made with the Dentaphone satisfy 
me that it is all that it is claimed to be. 

The deaf will find in it a means of relief which they have never enjoyed from the 
use of the ordinary ear-trumpet. I am, Yours respectfully, 


From Dr. WM. A. ROTHACKER, Professor of Anatomy in 
Cincinnati College of Medicine and Surgery, and Pathologist 
to Cincinnati Hospital. 

408 Race St., Cincinnati, September 26th, 1879. 

I have had the pleasure of observing the experiments made with the Dentaphone, 
and I have used the instrument myself. It acts by conduction of sound through the 
teeth and bones of the face. When a person speaks, even at the distance of twenty or 
thirty feet away, the sound causes a vibration of the diaphragm of the instrument, 
which vibration is communicated to the teeth through the mouth-piece. When I 
stopped my ears so that I could not even hear the voice of the speaker, I heard 
distinctly every thing that was said when using the Dentaphone. 

I have no doubt that the Dentaphone will in time supersede every form of that 
very inconvenient instrument, the ear-trumpet, and I believe aurists can make use of it 
in diagnosis of diseases of the ear. WILLIAM A. ROTHACKER. 


From J. WM. JOHNSON, Attorney-at-Law, of Moulton, 
Johnson and Levy, Lawyers. 

Cincinnati, October 2d, 1879. 

I am glad to express my satisfaction with the result of the experiments made with 
the Dentaphone. 

Being compelled myself to use a speaking tube or trumpet, I am able to form a 
better comparison than one whose hearing faculties are unimpaired. 

Though the Dentaphone you had was an imperfect one [Note. — This testimonial 
was written before the Dentaphone was perfected, the instrument used being a rude 
model of wood.] I could hear as well with it as with the trumpet, and its more con- 
venient form and size commend itself to favor upon sight. 

I would certainly advise all deaf persons to obtain one, whether they use a trumpet 
or not, and doubtless it will prove serviceable where, in many instances, the trumpet 
would not. Very respectfully yours, 


From Professor R. P. MacGREGOR, Principal Deaf Mute 


Franklin Street School, Cincinnati, October 1, 1879. 
The very interesting experiments made with the Dentaphone on the pupils of my 
department resulted as follows: 

The majority of them could hear sounds and described them as differing from one 
another in intensity. Some of them who had learned to speak before losing their hear- 
ing attempted to repeat the sounds as conveyed to them by the instrument, and with 
fair success. 

. As a means to enable the deaf to hear the Dentaphone is of great efficacv, etc., etc. 

R. P. MacGREGOR. . 

From Dr. ED. S. McLEOD. 

Corner State and Jackson Sts., Chicago, October 1st, 1879. 
I am highly pleased with the Dentaphone which you were kind enough to send me. 
The experiments made with it are sufficient to satisfy the most skeptical that not only 
the deaf and partially deaf can be made to hear, but that congenital mutes may be 
taught by spoken words instead of by signs. The small size and neatness of your in- 
strument render it a very convenient substitute for the clumsy ear-trumpet which it is 
sure to displace. No other invention with which I am acquainted can confer such a 
benefit upon any portion of humanity as your invention places within reach of the 
deaf. Very truly, 

ED. S. McLEOD, M. D. 

1 1 


533 Sycamore St., Cincinnati, October ioth, 1879. 

In the experiments which I had the pleasure of witnessing in the Deaf and Dumb 
School a few days ago, I observed that those who could never hear or distinguish 
sounds of any kind, immediately perceived the different sounds produced by different 
words, but of course could not recognize them, never having heard them before. The 
deaf mutes whose hearing had been lost within a few years, could hear and distinguish 
words quite readily. Those who could not hear unless spoken to very loudly close to 
the ear could, with the Dentaphone, readily hear the ticking of a watch, and at a dis- 
tance of twenty feet could readily hear and understand ordinary conversation. 

This instrument will in a short time displace altogether the clumsy ear-trumpet, and 
will be used by all suffering from deafness in every degree. 



The following extracts have been selected from a great number of press 
notices, secular and religious, which appeared in the leading newspapers of the 
country at the time of the invention of the Dentaphone. 

From THE NEW YORK HERALD, September 28th, 1879. 

(CINCINNATI GAZETTE, September 25th , 1879.) 

Experiments made with a new instrument for conveying sounds to the deaf. 

A well-known gentleman of Cincinnati has for some time past been 
experimenting with a new invention called the Dentaphone, which is in- 
tended to supplant the old ear-trumpet for use by the deaf. The Dentaphone 
consists of a small electro-microphone. * * * The manner of working 
the instrument is very simple, and can be briefly described as follows : 
* - * * xhe theory advanced is that the sound is conveyed through the 
.nerves of the teeth and the bones of the face to the auditory nerve, which, 
owing to some defection of the ear caused by disease, is not approachable 


through the usual channel to the brain. Some very interesting tests of the 
Dentaphone were made at the Deaf and Dumb Department attached to the 
Third Intermediate School yesterday morning. * * * 

Among others was one of a bright looking colored girl who was entirely 
deaf. The experimenter talked to her at a distance of about twenty-five 
feet, and she repeated after him every thing which he said. Another was a 
little girl who had been deaf and dumb from birth. Using the mute alpha- 
bet, she informed the teacher in charge that she could hear that one state- 
ment of the gentleman was made in a louder tone of voice than another, 
but that she could not understand what he said, never having been able to 
hear such sounds before. 


{September ijth, /Sy<p.) 

It was found that the partially deaf could hear distinctly with the outer 
ears entirely closed. In one of the experiments a man totally deaf, who 
had not heard any sounds for forty years, said the sounds were distinct, 
pleasant and seemed familiar. 


[September 26th , i8jg.) 

A new invention by a gentleman of this city, has, within the past week, 
been exhibited at the office of the Herald and Presbyter, of the Christian 
Standard, at the Franklin Street Public School and at various other places ; 
and has been tried on persons of all degrees of deafness, enabling them in 
every case to hear distinctly. The Dentaphone, as it is called, consists of 
a small chambered box, peculiarly made, and containing a delicate vibrat- 
ing diaphragm. * * * In one experiment in the office of the Herald 
and Presbyter, on a well-known clergyman, who has been deaf for years, 
every thing said in the room in an ordinary tone of voice was heard with 
the utmost readiness and clearness; and it was amusing to observe how 
quickly he heard and replied to some remarks made about his deafness 
which were not intended for him to hear. In other cases those who had 
not heard with distinctness for years, seemed to regain the lost sense per- 
fectly while using the Dentaphone. 



(October Jth, 1879.) 

A well-known gentleman of this city has invented a simple instrument 
which promises to revolutionize our ideas of the mechanism of hearing, and 
bring comfort and happiness to the many sufferers from deafness through- 
out the land. By it not only the deaf, and partially deaf, are enabled to 
hear, but the hearing is even said to improve under the use of the instru- 
ment, so as in certain cases to encourage hopes of the final restoration of 
the sense. Persons of all grades and degrees of deafness have been ex- 
perimented upon, and in every case with the same result, viz.: that the deaf 
person could carry on conversation and distinctly hear every thing that was 
said to him when using the instrument, though ordinarily so deaf that with- 
out it he might be unable to recognize the loudest words spoken. One 
object of the inventor has been to make the Dentaphone of such a size that 
it can be conveniently carried, and so well has this been succeeded in, that 
the completed Dentaphone measures about two inches across and about an 
inch in thickness. Being so compact, and much in shape like a watch, it 
can readily be carried in the vest pocket when not in use; and many of 
our citizens who have hitherto carried the clumsy ear-trumpet, are rejoicing 
in the prospect of discarding them for this more convenient, as well as much 
more effective, invention. * * * 


(September 27th, 1879.) 

A gentleman of this city has invented an instrument which has been 
tested in th- office of the Herald and Presbyter, the Christian Standard and 
the Franklin Street school house, on the deaf and dumb, and with the most 
surprising results. What spectacles are to the near-sighted the Dentaphone 
is to the deaf, and enables them to hear every thing spoken in their 
vicinity in an ordinary tone of voice with wonderful clearness and dis- 
tinctness. The instrument has been tested in every imaginable way and 
with uniformly satisfactory results, and clergymen, scientists and physicians, 
who have seen the Dentaphone in operation, pronounce it the most admira- 
ble and useful invention of the age for the relief of the deaf, and im- 
mensely superior to any ear-trumpet or other device hitherto used for a 
similar purpose. 



{September 24th, 1879. ) 

There seems to be no limit to the number and importance of inventions 
of the present day. First the phonograph and the telephone, for recording 
and transmitting sound; then the microphone, for intensifying it; and now 
the Dentaphone, by which the deaf can hear through their teeth. The 
Dentaphone is the invention of a gentleman of this city, and was tested a 
few days ago in the office of the Herald and Presbyter. * * * 

The deaf person simply holds the instrument — which is of such a size 
that it can be readily carried in the vest pocket — in the hand, with the 
mouth-piece against the teeth of the upper jaw, and hears what is said 
without any aid from the outer ear. Any one can, by closing the ears and 
standing at a distance from the speaker, test the instrument, the spoken 
words being heard with remarkable clearness and distinctness. The Denta- 
phone, as the new invention is called, will be on exhibition in our city in 
the course of a week or so, and is already exciting much interest, particu- 
larly among the deaf and their friends. 


(September 23th, 1879.) 

Its test in the Deaf Mute School yesterday. 

There was an interesting test made yesterday afternoon of the Dentaphone 
in the room of the deaf mutes in the Franklin Street school. * * * 

The sound enters through the instrument on the principle of the micro- 
phone, is conducted to the teeth-piece, and thence through the teeth to the 
auditory nerve. It was the purpose to test the instrument and see whether 
a sound could be conducted to a deaf mute. * * * These all heard to 
a greater or less degree, according to the nature of their deafness. In the 
case of one little girl, who could not distinguish words unless shouted into 
her ear, the Dentaphone was used with success, and she heard and by signs 
repeated short words spoken in an ordinary tone of voice. * * - * A 
colored girl, who was entirely deaf, but who was not mute, heard distinctly 
words spoken in an ordinary tone and repeated them. * * * 


(September 2 h /th, 1879.) 

A new invention by a gentleman of this city has been tested in our office 
this week. By it the deaf are enabled to hear through the medium of the 
teeth. The principle of the invention is that the vibrations of sound-waves 
striking on a diaphragm, set it in motion, and this motion is conveyed 
through the teeth and the bones of the head to the nerves of hearing. 
The Dentaphone can be made small enough to be carried in a watch fob. 
* * * In the Standard office the experiment was fairly made, and a 
person with stopped ears, * * * could hear what was said in an ordi- 
nary tone at a distance of thirty feet. This instrument will be on exhibition 
in this city in a few days, and it is sure to attract general attention. * * * 


(September 2jth 9 i8fg.) 

This wonderful invention is the handiwork of a well-known gentleman of 
this city. * _.# * The degree of deafness does not seem to affect the 
clearness of sound heard through the Dentaphone, as the outer ear is entirely 
foreign to the process used. Those, who for years have carried an ear- 
trumpet, on testing the Dentaphone, express themselves as highly pleased 
and are desirous of immediately discarding the clumsy ear-trumpet for this 
more convenient and effective invention. 


( September 28 th , 1879 • ) 

The deaf and partially deaf can, when holding the Dentaphone in the 
hand, hear distinctly what is said to them in an ordinary tone of voice by 
any person in the room, and carry on conversation so readily that their 
deafness can scarcely be noticed. In experiments made on the deaf it was 
found that those who had lost their hearing for years readily heard and un- 
derstood, and many who have carried ear-trumpets are waiting the com- 
pletion of this invention to discard them forever. * * * 


The preceding pages will, we believe, give the reader as accurate and 
perfect an idea of the construction and mode of action of the Dentaphone, 
as it is possible to obtain from any written description. We have taken 
pains, besides, to collect and present the opinions of well-known profes- 
sional men, and of the various leading newspapers, and we believe a care- 
ful perusal of this pamphlet will furnish the reader with the desired 
information in almost every case. If there should be any points omitted 
we will be glad to supply them, and invite correspondence in regard to 
them at any time. 

The directions for using the Dentaphone are very simple, and every in- 
strument sent out is accompanied by full instructions as to its use in all 
ordinary cases; also, as to the proper mode of employing it in educating 
children with defective hearing, the deaf and dumb, etc., etc. 

We are constantly in receipt of letters containing inquiries as to the size 
and weight of the Dentaphone, its liability to get out of order, etc. This 
information the preceding pages will supply, though we may here repeat: 

In size and shape the Dentaphone much resembles an old-fashioned silver 
watch, and weighs less than two ounces. The construction is so simple that 
it is impossible for it to get out of order unless intentionally injured or broken. 


Ordinary Conversational Size, - $8.00 

Large Size for Operas, Concerts, etc. - 12.00 

Either size is sent by mail or express, prepaid, on receipt of 
price. Parties ivho desire to order by express, C O. D., must pay 
all express charges. 

From its small size and weight the Dentaphone is most con- 
veniently sent by mail. 

Send money by Post-office Order, Registered Letter, Draft or 
Express. Write your name and address in full* Address 


387 Vine Street, CINCINNATI, O. 

Special Notice. 

^ ♦ 

The Dentaphone is constantly on exhibition at the 
office of the AMERICAN DENTAPHONE COMPANY, and is daily seen 
and tested by Persons of all Degrees of Deafness, as 
well as by Physicians, Scientists, Members of the Bar 
and of the Press; and all agree in pronouncing it one 
of the niost valuable inventions of the century for the 
relief of a large class of sufferers. The Deaf and their 
friends, as well as the general public, are cordially 
invited to visit our office and see the Dentaphone in 

Persons who are not Deaf can test the Dentaphone 
by closing the ears with the fingers and standing at a 
long distance from the speaker, when every word spoken 
in a low tone of voice is heard with the utmost distinct- 
ness. In this way persons who can not possibly visit 
our office for themselves, can often have the opinion 
of a reliable friend as to the effectiveness of the Denta- 

It is expected that in a few months the Dentaphone 
will be in extensive use in every part of the country, 
and persons who have Deaf friends can be assured that 
in bringing this invention to their notice, they are 
rendering them a service that should secure life-long 
gratitude in return. 


The DENTAPHONE displaces Every Form of Ear-Trumpet. 
It does so because it is much more convenient to use. 
It does so because it is much more effective 
It does so because it is more than an Ear -Trumpet, acting 
perfectly where an Ear-Trumpet is of little or no service. 

While the Ear -Trumpet, by intensifying sounds, may so injure 
the ear that, after a time, a larger and more powerful Trumpet 
has to be used; with the Dentaphone, on the contrary, the 
perception of sounds becomes better, and the longer the in- 
strument is used, the more perfectly is every thing heard. 

U^TTor the efficacy of the Dentaphone in enabling the 
Deaf to Hear, see Reports of Rev. Isaac Errett, of Drs. Roth- 
acker and McLeod, of J. M. Johnson, Attorney-at-Law, who 
has himself carried an Ear-Trumpet for several years ; also 
of various leading Newspapers, both Secular and Religious. 

IPjrTor experiments on the Deaf and Dumb, see Reports 
of Prof. MacGregor, Principal of the Deaf-Mute School ; of 
Dr. John Shaller, who was present at these experiments, and 
also of Cincinnati Enquirer and Gazette, the latter quoted in 
the New York Herald. 

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