showing the distance in yards ot infantry. An exterior ringy

is graduated fur showing the distance in yards of cavalry. By

means of interior teeth t>' on the flange h engaging pinions c c

: on the screw-pins (/ d\ two wires are caused to approach or re-

i cede from each other ; when the>e exactly coincide with the

extremities of tlie object, the number beneath the index o, upon

the scales 6, indicates the distance if infantry be observed, or

upon /"if the object be cavalry, g g' are the tield-lenses, and k

I is theobject-gia.HS.

1 Rochon's double-image telescope has within its tube a prism
1 of Iceland spar a mineral possessing the power of double re-
I fraction), which diviiles the pencil of rays into two pencils di-
verging from each other at a determinate angle. This prism is,
by hieans of a rack and pinion, movable from end to end of the
tube. It is moved back or forth nntil the edges of the two
images formed by the prism are in exact contact, when an in-
dex on the slide indicates the distance according
to a scale engraved on the outer surface of the
tube.

The binocular marine-glass of M. Lorieux, of
Paris, is designed to determine distances by the
angle subtended by an object of known dimen-
sions. It comprises two telescojies, the axes of
which may be thrown out of parallelism by an angular
! movement around an axis joining the two eye-pieces. This
1 forms a double image of the object, which appears single when
the two tubes are piirallel. One of these images will appear
directly over the other; and when their edges are in contact, the
angular distance between the two tubes is equal to that sub-
tended by the object at the eye of the observer, whence the
distance is readily inferred.

Another form of telemetric marine-glass by the same optician
I has a vertical plate on each siJe of the axis of the object-glass
of the telescope These are made to approach to or recede from
each other by means of a right-handed screw on one side, and
a left-handed screw on the other, the distance of the object be-
ing inferred from the distance apart of the two plates when
their ejges exactly coincide with the extremities of the object.
In later constructions of this instrument, the edges of the platte
I are placed horizontally, as being generally more convenient.
I The prism- telemeter consists of two prisms connected by a
j measuring-chain or tape-line, serving as a base for the triangle
1 which determines the distance. The two observers face each
other. The difference in the apparent direction of the object^
as viewed by reflection in the prisms, indicates by a scale at-
tached thereto the distance of the object.
The telemetricai telescope of Captain Gautier, of the French
\ artillery, indicates the distance of an object by the angles formed
' by it at two different stations successively. The object is
viewed by reflection from a prism which causes a known devia-
tion, 3°, in its apparent direction, and from two opposite mir-
rors, all in the tube of the instrument.
An electric telemeter fur ascertaining the distances of objects
I in motion has been invented by Captain Kocziczka, of the
Austrian engineer corps.

Two points of observation at a known distance apart are con-
nected by a telegraph-wire. At each station is a telescope,
I parallel to the axis of which, and turning with it, is a long thin
needle. A second needle turns on a point representing the
other station, and is connected with the wire therefrom. When
I an object is observed simultaneously at each station, the angle
I formed by the two needles — one following the motion of its
I own telescope, and the other that of the telescope at the other
I station, with which it is electrically connected — fixes the
position of the object on a plat of the country placed on the
table on which the instrument is mounted.

An instrument analogous to this was devised by the Archduke
Leopold, to determine the proper time to explode a torpedo
when an enemy's vessel passes over it. If a scries of torpedoes
be arranged in a straight line, one station is placed on the pro-
longation of this line, while tbe other commands a cross view
of it. When a vessel passes over this line, the observer at the
I first station touches a key, which closesa circuit passing through
both stations. The second
observer, having his tele-
scope, which is provided
with a metallic arm that
touches succe.'yiively a .series
of terminals communicat-
ing with the conductors,
will, at the same moment,
by the movement of the
telescope, bring this arm in
contact with the insulated
wire belonging to a torpedo,
if the vessel passes directly
over it. exploding the charge.

Balbreck's telemetric double-telescopeconsists of a square
tube or box, pivoted on a ball and socket joined at the
top of a tripod, and containing two mirrors turning on
vertical pivots. Thc^^e mirrors are partly silvered and
partly transparent, and are provided with tangent screws,
each carrying a divided circle with an index, by which the
amount of movement may be read. Two telescopes enter



TELEPHONE.



2514



TELEPHONE.



the tube at right angles from opposite directions ; one at each
end just beyotid the uiirrors. A rectangular glass prism is placed
at t.ie focus in the angle to change the direction of the rays.
The distance between the centers of the mirrors is one metre.
Openings are made in the side-' of tlie box opposite t.iu mirrors
to a luiit light from the obji^et to be observed.

In observing, the box is turned until the object seen by re-
flection i* brought into coincidence with the central line ot the
telescope at the other end. Through the transparent part of
this mirror the object wid be seen by reHectiou, but not on the
central line. It i-i brougiit into coincidence with this by means
of the tan.;cDt screw. Tne box is now revolved 18U-, and the
object vie.ved through the other telescope, and adjustments
made similar to those tirst described, the box being turned as
before, bnnginij; the second image again to coincide with the
first. The divided circie of the first mirror will then show very
nearly the true parallHX ; a correction is, however, necessary if
very accurate results are desired

The telemeter of Captain Oautier.of the French army {Fig.
625'>), consists of a tube «, having an opening b at oni- side, and
containing two mirrors set normally at an angle of 45°, one of




Gautier's Telemeter.



which (c) is fixed, and the other (d) admits of slight movement
by means of a thumb-screw e. A ring /turning on the axis of
the instrument carries a prism, through which an object may
be viewed by direct vision.

In measuring distances, the observer selects a distant and
well-defined object nearly at right angles to that whose distance
is to be determined, and having brought the zero or " infinity "
lino on the ring opposite an arrow-mark on the tube, he views
the first object or " natural signal " by direct vision through
the eye-tube g-, looking over both the mirrors and tlirough the
prism. By turning the screw e, the image of the object whose
distance is souglit, and the rays from which, passing through
the opening 6, are rcdected from c to (/, and thence to tlie eye,
is brought into coincilence with the natural signal. lie then
steps back a certain distance, say 20 yards, on the prolongation
of the line pa.^sing through this tirst station and the luitural
signal. This distance, which serves as a base line, should not
be less than ^ joo of that of the station from the object whose
distance is sought. The reflected image wid no longer coincide
with the "natural signal'' seen by direct vision through the
prism. By turning the ring f the prism is revolved until its
refractiou ugain causes the two images to coincide. The ring
is provided with a graduated scale containing a series of factors
by which the length of the base must be multiplied in order to
obtain the distance of the object. That factor which stands
opposite the arrow on the tube is the proper multiplier.

These factors are derived by a simple calculation, from the
trigonometrical properties of a triangle supposed to be right-
angled at the second station. Should the first and second sta-
tions, however, not be precisely in line with the natural signal,
a cori'ectiou may be applied, depending on tiie amount of this
angular variation; but this correction is so small, within the
Iimit.5 of angular measui'ement, as to be neglected in ordinary
practice.

The ring may, on the same principle, by assuming one or
more invariable base-lines, be so graduated as to give the dis-
tance directly in yard.s or metres. See also Wilson's United
States patent", September 29, 1868, No. 82,669.

Tel'e-phone. An instninient for conveying sig-
iiaLs liy souiul. It may consist of a steam-wliislle, a
fog-truinpL't, or other audible alarm. The term, un-
til lately^ ha.s been particularly applied to a signal
adapted for nautical or railroad use, in which a body
of compressed air is releaseil from a narrow orifice
and divided upon a .shar]> edge, in the manner of a
steam-whi.stle.

Tlie term is now acipiiring a different signification.

The subject of the number of vibrations per second, as con-
stituting a given note, has been considered under Musrc,
Pitch, Pipe, etc, : and the mode of counting the vibrations
under Sirsn. The vibrnscope is another instrument invented
by Duhamel for the same purpose. See also Metronome ;
Tonometer.

Articulate sounds are accompanied by the expul-
sion of air from the mouth, which impulses vary in



quantity, pressure, and in the degi"ee of suddenness
with which thi*y connnence and terminate.

An instrument which will record these impulses
ha.s been termed by its inventor, Leon Scott, a
phonaultxjraphf or j^h-onograph, and by Jlr. liarlow
a togograph; the pressure of the air in speaking is
directed against a membrane which vibrates and car-
ries with it a delicate marker, which traces a line on
a traveling ribbon. The excursions of the tracer are
great or small from the base line, which represents
the (piiet membrane, according to the force of the
impulse ; and are prolonged according to the dura-
tion of the pressure, diiferent articulate sounds vary-
ing greatly in their length as well as in intensity ;
farther, another great ditference in them consists in
the relative abruptness of the rising and falling in-
tlections, which make curves of various shapes, of
even or irregular shape. The smoothness orrugged-
ness of a sound has thus its own graphic char-
acter, independent both of its actual intensity and
its length.

Barlow's lns;o^raph, described in the London " Popular
Science Review," Vol XIII. page 278, eC seq., consists of a
small speaking-trumpet, having an ordinary mouth-piece con-
nected to a tube, the other end of which is widened out and
covered with a thin membrane of gold-beater's .>-kin or gutta-
percha. A spring presses slightly against the nieuibraue, and
has a light arm of aluminium, which carries the marker, con-
sistiug of a small sable brush inserted in a glass tube cont;uning
a colored liquid. An endless strip of paper is caup* d to traverse
beneath the pencil, and is marked with an irregular curved line,
the elevations and depres-

Fig. 6257.



Grrman r jiro/nn*jed
Trombone



sions of wiiich correspond
to the force, duration, and
other characteristics of the
vocal impulse. The lines
thus traced exhibit remark-
able uniformity when the
same phrases are successive-
ly pronounced.

Fig. 6257 shows curves ob-
tained by Mr. Charles A.
Morey by the interposition
of a light lever between the
membrane and the smoked
glass, which is drawn along
beneath the style, whose excursions are much magnified by the
lever. The curves show respectively the tongue trill or Ger-
man r prolonged, the mark

produced by the .<;ound of a » Fig. 6258.

trombone, and by the sound '
of 00 in mood. See "Ameri-
can Journal of Science and
Arts," August, 1874, pages
130. 131.

Fig. 6258 shows a tmcing
from the utterance of the
word " incomprehensibili-
ty," with dilTerent degrees
of effort. It will be noticed
that while a certain varia-
tion occurs due to the ener-
gy, each sound preserves a
specific character.

Fig. 6259 shows in the up
per portion the effect of
words of quantity which re()uire a large volume of air, and oro
maintained a relatively louger time than the more explosive .or
intense Icind.

The lower diagram is what the tracer wrote when the familiar
stanza from " Hohenlinden " was repeated.

A much more delieate instiunient for obtaining
sonorous vibrations has been made bv Trofessor A.
Graham Bell and Clarence J. Blake, M. P., of Pios-
ton, Ma.ss. (June, 1S74), by using the i/innbrana
tifmpani of the human eai- as a phonautograph. Dr.
Blake's mode of exposing the middle ear without
injuring the o.s.sicnlfc or the delicate tymjtanic mem-
brane is described at length in the " 15o.ston Medi-
cal and Surgical Journal," February 4, 1875, pages
121-123.

The stapes was removed, and a short style of hay substituttjd
of about the same weight, so as to increase the amplitude of the
vibrations and afford means of ob^1ining tracings upon smoked
glass, as in the phonautograph experiments. The membrane ia
kept moist by a mixture of glycerine and water, and the speci-



oo in inood



Lines obtained by the Phonauto-
graph.



Jncnmprth tii nihility
Logogrnphic Curves.



TELEPHONE.



2515



TELEPHONE.



Fig. 6259.




And /urio'ds ettry charffer nfighd,

3b join the dreadful retxlry.
Logograp/tic Cnrt-fx.

men attached to a perpendicular bar sliding in an upright post,
and moved by a ratchet-wheel. To the upright is attached,
horizontally, a metallic stage ?ix inches in length, upon which
slides a carriage with a gla^s plate, and having a regular move-
ment given to it by wheel and cord. A bell-shaped mouth-
piece is inserted in the external auditory meatus and luted in
position.

The vibrations of the membrane due to a musical tone sound-
ed in the belt may be observed by means of a ray of light
thrown upon small specula of foil attached to the malieuSj in-
cus. or to ditterent portions of the mfmi/'ana tympani, or may be
recorded on smoked

glass by a style fas- Rg. 6260.

tened to the descend-
ing proces.s of the
tnnllfus or' incus by
means of glue, in a
line with the long axis
of the prnce.-s'', and
extending downward,
so as to reach the
plateof smoked glas«,
which is moved at a
right angle to the ex-
cursion of the style;
the latter then traces




a wave - Hoe corre-
sponding to thcch-ir-
acterand pitch of the
musical tone sounded
into the ear.

As the gla.«s plates
present plane sur-
faces, and a-« the point
of the vibniting style
sweeps through the
segment of a circle,
the curves obtained



The Membrane oftke Tympanum used as a Phonnulosii-ftp'i



iare apt to be discontinuous, especially when the amplitude is
great. To obviate this difficulty, a sheet of glass is employed
having a curvci surface, the concavity being presented to the
' style. The sheet of glass is a section of a cylinder whose semi-
' diameter is equivalent to the length of the style. In this way
, the point of the style never leaves the surface of the gla.«s, and
I the curve resulting from its vibration is continuous. The car-
bon film is preserved by pouring collodion upon it ; as soon as
\ this is dry. the film may be tloated off with water and placed
; upon a plane sheet of glass, or upon paper, and varnished in
the ordinary way.

See the following works : " Use of the Membrana Tympani as
a Phonautograph and Logograph, with Plates," Archive for
Ophthalmology and Otology, lS7(i. " Use of the Membrana
Tympani as a Phonautograph and Logograph," Boston Med.
and Surg. Journal, Feb., 1S75. " Mechanical Value of the Dis-
tribution of Weight in the Ossicula,"' Trans. Am. Otological
Society, 1874.
' Another step in the direction of the conveyance of .«ound con-
sists in connecting a uienibrane in a uiouth-trumpet by means
of a fine cord with a similar membrane in a trumpet appHed to
the ear of a person at a considerable distance, say in another
room. The sounds are audible, not merely as to pitch, but are
recognizable as articulate sounds. The writer knew an ofiicer
' who was with Nel.<-on at Copenhagen, who was wounded so that
his hearing was destroyed. He was in the habit of placing a
music-box against his teeth, or holding in his teeth a string
whose other end was shut tightly between the lid and the box.
Ue said he htarri very well.

The experiment of connecting distant sounding-boards, so
that one is made to vibrate in unison with the other, is familiar ;
' indeed, the synchronous vibration may be obtained even by the
vibrations of the atmosphere, as when the sounds of a piano are
repeated by those of a guitar which has been tuned in unison
and stood up in the corner of the room. This is even more
palpable wheu the guitar is laid upon the piano top.

"There is an experiment, first made by \\'heatstone, where
the music of a piano is transferred from its sound-board, through
a thin wooden rod, across several silent rooms -in succession,
and poured out at a distance from the instrument. The strings
of the piano vibrate, not singly, but ten at a time. Every
string subdivides, yielding not one note, but a dozen. All these
vibrations and subvibrations are crowded together into a bit of
deal not more than a quarter of a square inch in cross section.
Yet no note is lost. Each Tibration asserts its individual rights ;
and all are, at last, shaken forth into the air by a second sound-
board, against which the distant end of the rod presses. Thought
ends in amazement wheu it seeks to realize the motions of that
rod as the music flows through it." — Prof. Ttsdall.Iu •' Mar-
tineau and Materialism."

From the mechanical transmission of sounds by
the air, string, or wooden rod, we pass by a decided
step to devices by wiiicli vibrations are made to pro-
duce rapiil contacts and breaks of an electric circuit,
and tlius become means of transmitting tones ; and,
conversely, to means of making rapid contacts, so as
to set matter vibrating, and causing it to generate
musical tones.

The knowledge that the pitch of tone depended upon the
rapidity of vibration was well known to Pythagoras : the gener-
ation of sound by motion is familiar in the vibration of strings

■ and wires in the iEolian harp, and the sound of the wind in a

i tube. The tuning fork is so proportioned that it produces
sounds of but one pitch, while its timbre depends on the qual-

' ity of its material, and its intensity upon the amplitude of its

; Tibrationg,

Besides the tone generated by the agitation of the atmos-
phere, it was observed as long ago as Vi^, by the Canon Gottoin
de Coma, that an iron wire of at least 10 yanls in length, when
stretched in the open air, spontaneously gives forth a sound
nnder the influence of certain variations in the state of the
atmosphere, the effect being due to the tninsmission of atmos-
pheric electricity. This transmission does not in fact occur in

, a continuous manner like that of a current, but rather by a

i series of discharges.

Mr. Beatson ha-s proved that the discharge of a Leyden jar
through an iron wire causes this wire to produce a sound if the
discharge is firet passed through a moist conductor, such as a

, wet string or animal tissue.

Professor Page in America, De la Kive in France, Gassiot in
London, and Marriah in Birmingham, discovered that rods of
iron placed in the interior of a helix through which a current
of electricity is passed give out decided sounds at the moment
when the circuit is made or broken.

Reis applied this discoverj' in his telephone. By causing the
circuit to be made and broken very rapidly, a musical note was
emitted by a rod placed in a helix traversed by the current.

De la Rive found that exactly similar sounds were produced
where the intermittent current was passed through the iron
rod it.self ; and Professor Bell has produced similar effects by
passing the current through retort carbon, plumbago, German-
silver wire, and platinum wire.

In fact, the intermittent current occasions a molecular Tibra-



TELEPHONE.



2516



TELEPHONE.



tion in the conductor throui;h which it is passed, whatever may
be the inateri.-il of which it is niude, inid this vibration may be
rendered audible by foiling up the conduetint;-wire and apply-
ing it to the car ; as, for instance, an empty helix of copper
wire, through which a discontinuous current is pusscd.

In tlie electro-magnetic telej)bone of Kirpatli, the telephone
sending-instrinuent consists of an open funnel in which the
tone is sounded, and a diaphragm of tliin el:u<tic membrane,
which is set in vibration by tlie tone, and which by its vibra-
tions continually makes and breakj^ the electiie circuit. The
number of breaks in a second corresponds with the number of
vibrations belonging to the
Fig. 6201- tone sounded (see Pipe,

jiagelTOS); and since tlie
current passes at the otlier
end of the line through a
helix around a soft iron
bar, this bur is magnetized
and demagnetized, alter-
nately, a^ many times in
a second as there are
vibrations in the
tone sounded at
tlie sending -in-
strument At each
demagnetisation,
a longitudi nal
shrinkage of the
bar occurs, and a
resulting sound ;
this is rendered
hiore audible by
placing thi* bar on
a delicate sound-
ing-board, which
partakes of tlie
vibrations sy n -
clironously with
those of the ori-
ginal membrane,
and n-producea
the same sound.

Fig. ♦J2lU shows
one of Ueis's tel-'
ephones, used by Legat in his experiments upon Tetephonie..
The discontinuous current, produced by the osi-illating lever
which vibrates in concert with the membrane on the end of the
trumpet, is passed tijrough an electro-magnet (shown beneath),
60 as to occasion vibration iu its armature, which is attached to
a sounding-board.

Fig. 6262 priucipuUy differs from the other in its receiving-
instrument. The intermittent current traverses a coil surround-

Fig. 6262.




iifiA'5 Telephone.




Reis's Telephone.

ing a rod of iron, occasioning a molecula- vibration in the iron.
The resulting sound is rendered more inten.^e by placing the
rod and helix upon a sounding board

Another form of receiving-instrument is thus described by
De la Rive: —

■' The most brilliant sound is that which is obtained by
stretching upon a sounding-board well-annealed wires, ' o-i or
-'^n of an inch in diameter and from 3 to feet in length. They
are placed in the axis of one or several bobbins, the wires of
which are traversed by electric currents, and they produce an
assemblage of sounds, the efTect of which is surprising, and
which greatly resembles that to which several church-bells give
rise when vibrating harmonically in the distance "

De la Rive mentions one or two rhrntnmes or circiiit-hren/cer^,
forms of apparatus employed by him in his experiments upon
the production of sound telegraphically, for the purpose of
making and breaking the circuit very rapidly.

Fig. 6263 is simply a toothed wheel so arranged as to make
and break contact with a spring resting against the edge. By
giving tlie wheel a movement upon its axis, we cause the plate
to leap from one tooth to another ; each leap produces a rup-
ture in the circuit, which is closed again immediately after-
ward. The musical tone given out l)y the plate, when we liave
no other means of mcasuriu>^ it, ^ivcs us exactly the number of



times that the circuit has been opened and closed, that is to
say, interrupted, in a second.

Fig. 6264 is another Ibrm of rheotome used by De la Rive,
consisting of four net-dies
arranged ujion a horizontal Fig. 6264.

rod, so as to dip into mer- _

eury alternately when the
axis is caused to revolve.

62&3.





De la liii-e^s
tiheolome.



De la Rict-'s Cirruil-Bnaker or
Wieototne.



The two needles are inserted perpendicularly and parallel with
each otlier, and so arranged that when they are )mnier>ed
simutaneously in two capsules filled with mercury, and insu-
lated from each other, the circuit is closed : and when they are
not innnersed, it is ojien. A clockwork movement, or simply a
wijich moved by the hand, gives a rotatory movement to the
axis; whence it follows that iu a given time — a second, for
example— the circuit may be closed or interrupted a great
number of times.

Attention has long since been directed to the utilization for
telegraphic purposes of the means afforded and effects elicited