IMPROVEMENTS INI
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by John Rowlands Edwards at the Office
of the Commissioners of Patents on the 7th February 1879.
'
JOHN ROWLANDS EDWARDS, of Liverpool, in the County of Lancaster, Super-
IMPROVEMENTS IN AND APPERTAINING
intending Engineer of Postal Telegraphs.
TO SOUNDERS FOR TELEGRAPHIC PURPOSES."
The object of this Invention is to introduce improvements in that class of instru-
ments known as "sounders," both double and single, which shall be actuated
directly by the line current, thereby rendering unnecessary the intervention of a
relay and local battery power, as in the case of the ordinary "Morse" sounder and
Bright's "bell instrument," and thus simplifying and economizing the means of tele-
graphic communication.
The acoustic telegraph possesses great advantages over the visual telegraph, and
my double sounder can be advantageously used in the place of the old single needle
instrument.
First. The single form of the instrument consists of a suitable stand carrying a
permanent magnet, preferably of approximately horse shoe form, one pole being
made preferably longer than the other and placed uppermost. Below this long pole
I fix an electro magnet having a soft iron core passing through the long pole of the
permanent magnet, and magnetized by it, and made in two parts capable of being
adjusted at any required distance from each other by a screw or its equivalent
carried on a bracket on the long pole of the magnet or otherwise.
Below the shorter pole of the permanent magnet I place another electro magnet,
with an iron core capable of being adjusted in regard to its height above the coil
by adjusting screw or otherwise below. It will thus be seen that the iron cores of
the electro magnets face each other, with a space between them capable of being
adjusted at will.
A soft iron armature carrying at its outer end the brass hammer for striking the
sound plate, bell, or drum in the usual way is hinged or pivoted to the short pole of
the permanent magnet and magnetized by it.
The various connections are of course coupled up to the switch or key and battery,
as will be well understood.
In working the instrument a current passing through the coils of the electro
magnets reverses the polarity of the core of the upper electro magnet, releasing the
armature, which besides falling by its own gravity is attracted by the opposite pole

page_text: of the lower electro magnet, striking the sound plate or bell, and the frequency of
the sound is attained by operating the key in the ordinary way.
The lower electro magnet pole is not affected by the permanent magnet, as it is
magnetized by the line current only when passing.
"No reacting spring to raise the vibrating armature is needed, as the permanent
magnet magnetizing-the-pole-or-core-of-the upper electro magnet supports the
armature directly the line current is off, and this degree of magnetism is regulated as
described by having the upper core in two parts adjustable to each other.
Second. Instead of single instruments, as described, they can be duplicated in
-details,-using-two-coils.above-and-below, and-two-vibrating-armatures and magnets,
the principle being the same.
In this case the direction of the coils.in. one of the two instruments combined.in
one is the reverse of the other; consequently one current will sound one bell, -the
reverse current the other (differently sounding bell).