The Dallas daily herald. [volume] (Dallas, Tex.) 1873-1887, 1881-08-02

WIRE, battery, u condenser, an interfupter
or circuit breaker and a telephone. The
ends of primary or inducing coil arc cons
nec'ed with poles Of battery and in s,me
circuit are a eondenser.and small interIupler
whose vibrating tongue opens and closes the
circuit with great rspidity. TIE ends Of the
secondary coil on which the current is 10 be
induced are carried TO The binding posts of a
Bell telephone. When connections have all
thus been made the secondary coil is laid on
the primary or inducing coil, so that their
respective circumterences exactly coincide.
The circuit breaker IL then set In motion ..and
rapidly interrupted. The current through
the primary coil Induces another current of
higher intensity in secondary coil, as Is does
so a loud musical sound Il heard 10 the tele-
phone with which The Sec
ondary coil is connected Az
long as the 'curreat is maintained, and the
circumference of the two coils are kept in
exact coincident. the musical note in the
telephone does not change lis pitch or in
,ensity. If however the erperimenter slides
the upper coil along an inch or 20 upon the
lower their circumferences no longer cor
respond, and the intensity Of the musical
tone Is diminished. and Just in proportion as
the centres of tho fat coils are separated by
greater or lees distance the intensity of musi-
cal tone Is lessened or increased. When the
upper coil has been sldden over the lower
80 that they simply overlap the centre Of one
corresponding nearly with the point OF
circumference of other, the musical tone in
the telephone ceases II the upper coil ia
pushed little further to ono eide, so that II
overlsps still less tone, 1t 10 again heard. By
delicate manipulation " Is pos
sible to adjust the centres Of
the overlapping coils at such distance one
from tho other, that q perfect balance is
brought about, and when this is the case the
telephone mskes no sound whatever. Tho
entries of overlapping cols can not then be
moved either towards or away from one
another without causing tho telephone to
break its silence. When the coils are thus
balanced, the telephone is mute. II IL found
that what may be called the area of coinci-
dence, or In other words the area OF oveil p.
pil q parts of the two fiat coils, has become
highly sensitive to the approach of metal,
and msnitests its sensitvness by low note
in the telephone As loug as metal Ia kept
away from this area, the telephone remains
silent, but If piece of lead, for example,
brought within distance Of four or five
inches from the overlapping part of the
coils, there may be heard IN the telephone
faint but clearly perceptible note which be,
comes louder and louder rs the metal ap-
proaches the sepsityre surface and throws the
coils more and more out of balance. 1t will
readily be seen that under the guidance Of
the telephone the small area bounded by
the intersection circumference OF the
overlapping coils can be placed easily
| hon lat NhsN n
metal embedded In The body, provided the
metal does not le 10 great depth. As
soon hs the balance OF the coils begin TO feel
the disturbance csused by their approach to
the embedded bullet the telephone announces
the fact by faint, continuous musical note
and this note grows louder and loud'r, VIII 0
the overlapping parts Of the coil are directly
above the disturbing metal, when the
sound reaches It's maximum for convenience
of application 10 the body. The coils used
by Professor Bell, this morning, are
mounted in rectangular piece of walnut,
about seven inches in length by four in
breadth with screw posts st the corners for
wires and a handle at the back, by which 1t
could be held.
following is Professor Bells repsrt to the
surgeons upon to.day's experiment:
LA v.
W.sbiry,oo n. q Auyustist. ,ssl,
10 s me sn'geons In Attendance upon fresioen'
"""ou
GENTLEMEN; i; l peg 70 submit, lor your
information, q oIieI s'a'ement Oh Tue iesulss
obtained WIN .he new iolm inoue'lon
balance ID 'ne elper'men.s msue % .nls morn .L.
ing lor zoe purpose 0i me loestion Vi rue rue
ouiies III 'ne person ., ,he pIes,uen: ino
insuument was W.eu lor seh.,HV.hesS
several umes curing 'ne course Oh eiPeii'
menls, ana ~ was lounu 70 -
respond wen 70 sne preeeh's'ion ol
the nNHeheo pu'let : uEushce oi soou, i1ur
lnches rom me cons. Wneh 'ne % plorlhg
COILS were passed over 'na' part OF lne aodo-
men wbeie sonoroqs spos was oose,veo,ln
the experiment OF Ju'y zotn, ieeGie tone
was pefcelveo' out tne eject waa aualple ano
ior eousloerAo'e o'slsnSe arounu 'ns spos
tne sounos were LOO Iseole 70 90 enIreIy
Satisfactory. as nso reason 10 expec'
rom ,ne extreme sensnlVebess o, lns lnstfq-
menS mere was more nnarseu 'n'ce' Ia u
orler 10 ascertain whe'ner s,miia. founos