Improvements in the Construction of Electric Testing Apparatus.
Year: 1886

page_text: Date of Application, 17th Feb., 1886.
Complete Left, 16th Nov., 1886.
Complete Accepted, 7th Jan., 1887.
Improvements in the Construction of Electric Testing Apparatus.
I, JOHN SMITH RAWORTH of 24 Brazenose Street, Manchester in the County of
Lancaster, Engineer, do hereby declare the nature of my invention for IMPROVEMENTS
IN THE CONSTRUCTION OF ELECTRIC TESTING APPARATUS to be as follows:-
My invention consists in certain improvements in the construction of galvanometers
and detectors whereby their cost is reduced, their efficiency and handiness increased
and their repairs rendered both easy and inexpensive. In constructing my improved
galvanometer and my improved detector, I attach the various working parts
to the dial plate as usual, and I make the positive and negative connections to two
insulated studs or bosses also fixed to the dial plate. I place the said working parts
either vertically or horizontally in a box of timber or other suitable material, in which
guides are provided so that the dial plate may slide easily into or out of its place. The
piece of glass to cover the dial is also arranged to slide in similar guides. I mako the
box with contact springs of metal for the positive and negative studs or bosses
to press against so that the sliding into its place of the dial plate and the working
parts attached thereto, or the closing of the box will make the necessary
connections with the external terminals. In constructing the deflecting coils of my
improved galvanometer and of my improved detector, I propose to dispense with the
frames or bobbins on which the coils are usually wound by winding the wire on a
mandril or former, representing the usual bobbin, with shellac or other insulating
varnish or adherent material, which will make the bobbin sufficiently stiff and solid
without the use of a permanent bobbin or frame. I propose to render my improved
galvanometer and my improved detector more efficient for the ordinary purposes of
testing by inserting in the box with either of them, or by inserting in a box attached
to the box which contains either of them, one or more voltaic cells so that the
instrument may be always ready in a very portable and convenient form for making
any tests which are usually made with a galvanometer and battery or detector and
battery. I also propose to cover the face of the dial with a lid or cover hinged to the
box at its lower edge when the dial is vertical, which lid or cover will protect the dial
from injury when out of use and will carry a mirror, which when set at an angle of
about forty five degrees with the dial will enable the user to see the movements
of the needle when the instrument is placed on some support below the level of the
user's eye.
In the above statement a "detector" is supposed to differ from a "galvanometer'
only in the accuracy or exactitude of its indications.
"
TATTY Arr
TTתזזית

page_text: COMPLETE SPECIFICATION.
Improvements in the Construction of Electric Testing Apparatus.
I, JOHN SMITH RAWORTH, late of 24, Brazenose Street, Manchester, in the County
of Lancaster, but now of 112 Belvedere Road, Lambeth in the County of Surrey,
Engineer, do hereby declare the nature of this invention, and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
My invention consists in certain improvements in the construction of galvanometers
and detectors whereby their cost is reduced, their efficiency and handiness are
increased, and repairing thereof is rendered both easy and inexpensive..
In constructing my improved galvanometer and my improved detector, I attach
the various working parts to the dial plate as usual, and I make the positive and
negative connections to two insulated studs or bosses also fixed to the dial plate.
I place the said working parts either vertically or horizontally in a box of wood
or other suitable material, in which guides are provided so that the dial plate may
slide easily into or out of its place. The piece of glass to cover the dial is also
arranged to slide in similar guides. I make the box with contact springs of metal
for the positive and negative studs or bosses to press against so that the sliding into
place of the dial plate and the working parts attached thereto, or the closing of the
box will make the necessary connections with the external terminals. In constructing
the deflecting coils of my improved galvanometer and of my improved detector,
propose to dispense with the frames or bobbins on which the coils are usually wound
by winding the wire on a mandril or former, representing the usual bobbin, with
shellac or other insulating varnish or adherent material, which will make the bobbin
sufficiently stiff and solid without the use of a permanent bobbin or frame.
I propose to render my improved galvanometer and my improved detector more
efficient for the ordinary purposes of testing by inserting either in the box containing
the same, or in a box attached thereto, one or more voltaic cells, so that the instrument
may be always ready for use, and form a very portable and convenient apparatus for
making any tests which are usually made with a galvanometer and battery or detector
and battery. I also propose to cover the face of the dial with a lid or cover, hinged to
the box at its lower edge when the dial is vertical, which lid or cover will protect the
dial from injury when out of use. The lid or cover carries a mirror, which when set
at an angle of about forty five degrees with the dial will enable the user to see the
movements of the needle when the instrument is placed on a support below the level
of the user's eye.
In this specification a "detector" is supposed to differ from a "galvanometer "
only in the accuracy or exactitude of its indications, and it is to be understood that
the same construction of instrument can be used either as a galvanometer or as a
detector.
Referring to the accompanying sheet of drawings, Fig. 1 is a front elevation,.
Fig. 2 a side elevation, and Fig. 3 a plan with the cover removed of electric testing...
apparatus according to this invention. Fig. 4 is a side elevation, and Fig. 5 a view

page_text: as seen from the rear of the galvanometer or testing apparatus withdrawn from its
containing box or case. Fig. 6 is a diagrammatic view illustrating the electric con-
nections of the apparatus.
1 is a dial plate arranged to slide vertically in guides 2 in a box or case 3. To the
dial plate are secured insulated studs or bosses 4 and 5 to which are electrically
connected the ends of the galvanometer coil 6 which is constructed as hereinbefore
described, and is provided with needles in the usual manner. 7 is the glass front of
the apparatus; it is arranged to slide vertically, in the guides 2. 8 and 9 are metallic
contact springs or pieces against which the studs or bosses 4 and 5 respectively bear
when they are in place within the box or case 3. 10 and 11 are terminal screws in
electrical connection with the contact pieces 8 and 9 respectively. 12, 12 are two
voltaic cells constituting a galvanic battery enclosed within the box or case 3. The
positive and negative terminals of the battery are connected respectively to the
contact piece 9 and a terminal screw 13. 14 is an additional terminal screw
between which and the contact piece 8, a resistance 15 may or may not be introduced,
as desired, but to the use of such a resistance I lay no claim, as it forms no part of
iny invention.
16 is a lid or cover hinged at 17 to the lower side of the box or case 3;
it is provided with a mirror 18 for the purpose before mentioned.
This lid or
cover being closed against the front of the box or case 3 will serve to protect the
glass 7 when the apparatus is not in use.
The method of using the apparatus with or without the galvanic battery 12 and
with or without the resistance 15 will be readily understood from the diagrammatic view
Fig. 6 without further description. As will be understood, the divisions on the dial
may be either such as required in the case of a galvanometer, or such as required in
the case of a detector, according as the instrument is employed as the one or as the
other.
Having now particularly described and ascertained the nature of the said invention
and in what manner it is to be performed, I declare that what I claim is :-
The improved electric testing apparatus constructed, arranged, and operating sub-
stantially, as hereinbefore described with reference to and shown in the drawings
annexed, whether used with or without the battery 12, and whether with or without
the fixed resistance 15.
JOHN S. RAWORTH,
W. Lloyd Wise,
46, Lincoln's Inn Fields, London, W.C.,
Agent for the Applicant,