IMPROVEMENTS IN MICROPHONES
Year: 1884

page_text: I ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex
Engineer do hereby declare the nature of this Invention for "IMPROVEMENTS IN
MICROPHONES" and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
The object sought to be attained by this Invention is to render the microphone
constructed in accordance therewith exceedingly sensitive and this to a higher
degree than has heretofore been practicable. Moreover when the apparatus has
been once adjusted it is not liable to get out of order again it is moreover so
solidly constructed that it will bear heavy shocks without injury.
The advantages offered by the said Invention have been fully demonstrated by
experiments, even if a person speaks softly and at some distance from the apparatus
the words are clearly and distinctly transmitted over considerable distances.
The apparatus as shewn in the Drawings consists substantially of the following
parts:
.d are wooden crosspieces upon which are fixed vibrating strings fff of copper
or the like.
fff wires of copper or the like formed into helices so as to form vibrating
strings.
m m slides glued or fastened to the lateral walls or sides of the casing.
E. F hollow resonant box.
g. wooden frame or crosspiece supporting the vibrating strings ƒƒ f.
n. n. bottom of the resonant box.
1. 1 grooved longitudinal carriers serving for bearing the carbon cylinders k.
k longitudinal carbon cylinders.
h transverse carbon cylinders.
¿ improved induction coil.
The Drawings represent in
Fig. 1 elevation of the casing one side of the (outside view).
Fig. 2 top view.
Fig. 3 plan of the bottom of the box opened.
Fig. 4 section on line A. B Fig. 1.
Fig. 5 ton view of the resonant box

page_text: .
Fig. 6 section on line K. L of Fig. 5.
Fig. 7 section on line P. q Fig. 6.
Fig. 8 plan of the bottom of the box.
Figs: 1. 2. 3. 4. 5. 6 and 8 show an apparatus of suitable dimensions drawn to
about half size and Fig. 7 is drawn to about full size thereof.
The induction coil is more carefully made and stronger than heretofore.
Petroleum-black or smoke is used for covering the inside of the resonant box.
The number of transverse carbons & their shape and also their arrangement may
be varied and also manner of actuating them with relation to the longitudinal
carbons k.
The longitudinal carbons have exterior grooves notches, cells, sockets or
perforations for receiving the ends of the transverse carbon cylinders h.
2. The apparatus embodying this Invention may be made in various sizes and
shapes and be employed in telegraphic and telephonic lines.
Having now described the said Invention as communicated to me by my foreign
correspondent I claim
1) The construction of the box or casing.
2) The arrangement of the carbons and the manner of joining the longitudinal
and transverse carbons.
3) The resonant box E. F.
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4) The use of petroleum black (smoke) for covering the interior of the
resonant box.
5) The use of vibrating wires turned spirally and made of copper and the like.
6) The use of a greater or less number of transverse carbons in the apparatus
the arrangement and shape whereof may be varied as well as the manner of placing
them in connection with the longitudinal carbons k.
7) The providing in the longitudinal carbons k. of exterior grooves. notches cells
sockets or perforations for receiving the ends of transverse carbons h.
Dated this 3rd day of March 1884.
ALFRED J. BOULT.