Improvements in and connected with Electric Testing Apparatus.
Year: 1890

page_text: Date of Application, 8th Aug., 1890
Complete Specification Left, 8th May, 1891-Accepted, 15th Aug., 1891
PROVISIONAL SPECIFICATION.
Improvements in and connected with Electric Testing Apparatus.
ARTHUR ALBERT DAY, A.K.C. A.I.E.E. Electrical Engineer 60 Queen
Victoria Street E.C. HERBERT JOHN DOWSING Electrical Engineer 4 Queen
Victoria Street E.C. do hereby declare the nature of this invention to be as
follows:-
:-
Our invention consists of a new & improved form of portable electrical testing
instrument or instruments combined in one case. It usually consists of a box in
which is contained a suitable battery, a variable resistance, standard resistance
galvanometer, standard cell or cells, connections for forming a Wheatstone bridge
with keys & switches. An electric lamp may also be attached.
The instruments may be connected
following
iti
various ways among others the
1st. The battery galvanometer & key coupled in circuit with two terminals for
showing a current through & generally useful to the purposes of a detector.
2nd. The same as in No. 1 but with the variable resistance capable of being
introduced as a rheostat.
3rd. The battery, galvanometer, standard resistance & variable resistance,
coupled up as Wheatstone bridge for measuring resistances or for other purposes in
which the Wheatstone bridge combination can be used.
4th. The battery, galvanometer, variable resistance, standard cell, for the purpose
of comparing potentials by Poggendorff's or Clarkes method that is to be used as a
potentiometer.
5th. The battery coupled up with a small incandescent lamp for use as a portable
lamp, with flexible cord attachment for same.
H. J. DOWSING.
ARTHUR A DAY.
COMPLETE SPECIFICATION.
Improvements in and connected with Electric Testing Apparatus.
We ARTHUR ALBERT DAY A.K.C. A.I.E.E., Electrical Engineer, of 60 Queen
Victoria Street in the City of London, E.C. and HERBERT JOHN DOWSING,
Electrical Engineer, of 4 Queen Victoria Street in the City of London, E.C.
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 :-
The object of our invention is to provide in a compact portable form an apparatus
for use in electrical testing having a very wide range of application. Instruments
at present in use for taking electrical tests are usually made for one class of testing
only, and as a consequence when electrical measurements of various kinds have to
be made a number of instruments are necessarily employed.
In our invention we arrange various parts necessary for carrying out our object
in a convenient manner whereby instruments suitable for different uses in electrical
practice are immediately available wherein certain parts are used in common in the
constitution of the respective instruments instead of requiring those parts to be
separately provided for each, thereby forming one instrument, which is capable of
In order
being used in different ways and thus replacing a number of instruments.
to prevent the complication usually experienced in making connections for the
instruments at present in use we so arrange our compound instrument that all

page_text: connections communicating between one part of the instrument and another shall
be internal or self-contained so, that the operator, has simply to connect the parts to
be tested to the externally accessible terminals provided for that purpose.
In order to obviate the necessity of calculations as required with instruments at
present in use we so arrange and balance the various parts of our improved
apparatus that most of the results of the tests or measurements can be read off, in
direct figures from the scale, which is conveniently arranged for reading, thus
obviating the necessity of calculations required by the arbitrary or proportional
figures obtained from the instruments usually employed for testing purposes. The
improved apparatus is particularly adapted for the requirements of unskilled
persons. The apparatus is capable of being housed in a box of small and very
portable dimensions.
Fig. 1 is a general perspective elevation of the apparatus with the lid swung back
on its hinges so as to disclose the various parts, consisting of external case W, W, W,
galvanometer G, with detachable controlling magnet V, circular sliding scale Z,
contact keys d¹ & m', switches q & n, portable lamp L, with switch for same S also
terminals 3 & 4, standard cell contacts c¹ & c.
Fig. 2 is a plan view of the upper part of the instrument ( Fig. 1) carrying the
various working parts consisting of galvanometer G, circular sliding scale Z
provided with two sets of graduations one graduated into equal parts in the
ordinary manner the other graduated to show the proportion between the resistances
on either side of the sliding contact I, fixed circular disc carrying slide wire (parts
dotted) & pointer X, contact keys d' & ', switches P & N, light switch S
dotted circle O showing position occupied by standard resistance, standard cell
contacts c¹ & c², & case W, W, W.
Fig. 3 is a front view of the case in section with the lid shown in dotted
lines, W, W, W, the case, circular sliding scale Z, dotted lines showing the position
of frame of galvanometer QQ, galvanometer glass G.
.
Fig. 4 vertical section of parts adjacent to and supporting the slide wire
resistance vs. the frame of the box W, W, W, circular revolving scale Z revolving
on spindle Y which is fixed to circular disc X carrying slide wire, X being screwed
to a partition in the case.
་ ་ ་ས
Fig. 5 is the face elevation of the slide wire scale disc Z shewing screw heads for
fixing in brass bearing on which it revolves (shown in Fig. 4).
Fig. 6 is a plan view of the slide wire disc, pointer & scale disc, showing slide
wire disc X with slide wire E, E, and pointer also revolving scale disc Z.
Figs. 7 & 8 are two edge views of the roller contact maker & parts of the slide
wire & scale discs taken at different angles, roller contact maker T shown in
Fig. 8 with spring for making good contact, slide wire disc X & slide wire E; E,
revolving scale Z.
Fig. 9 is a side view partly in section of the galvanometer and parts for bringing
ts needles into operative position, frame of the galvanometer QQ attached to
underneath of top carrying rest of parts, galvanometer G, pivot of galvanometer b,
arrangement for unshipping galvanometer needle when the controlling magnet is
screwed off a, controlling magnet V.
Fig. 10 is a side view taken at right angles to Fig. 9. showing the same parts as
in Fig. 9.
Fig 11. is a plan view of the dial plate of the galvanometer G showing part of
scale & galvanometer needle.
Fig. 12 is an under side view of the frame of galvanometer Q Q.
Fig. 13 is a side view of one of the switches for putting the battery, or
an
nstrument or other part of the apparatus into operation, back contact P switch
ever, contacts i top of case u.
Fig. 14 is a plan of Fig. 13 the lettering is the same.
4

page_text: contacts springs for opening or closing the battery or galvanometer circuits or like
use d' press button contact u top of case.
Fig. 16 is the lower part of Fig. 15 showing contact springs.
Fig. 17 is the sectional elevation of lamp switch S showing plug contacts S¹ & S',
top of box u.
Fig. 18 is the plan of switch contacts S¹ & S
Fig. 19 plan of top of plug of switch S.
Fig. 20 shews side view of charging terminals shown as 5 & 6 on Fig. 22.
covered with ebonite y' to prevent short circuiting, & case u.
Fig. 21 side view of the ordinary terminals 1, 2, 3, 4, Fig. 22 used for connecting
the instruments to the various cables batteries etc. to be tested, top of terminal y³,
case W.
Fig. 22 is a diagram showing the various switches keys, resistances standard cell
or cells & other parts & the way in which they are connected up to the battery in
order to make the combinations herein described.
Fig. 23 to 33 show detailed diagrams illustrative of the various uses to which
differently arranged combinations of parts of the apparatus can be put & selection
of connection adopted for that particular use. When the apparatus is required to
be used for the following purposes the connections as named are brought into use.
Fig. 23. As Wheatstone bridge or to measure an unknown resistance. The
unknown resistance is connected to terminals 1 and 2 and connection is made from
1 through galvanometer key d² and back contact d to galvanometer terminal y';
through galvanometer and from galvanometer terminal to slide contact hon
resistance R. From terminal 2 connection is made to switch contact k, through
back contact to battery terminal «; also from terininal 2 to resistance R
at, through resistance and from to contact of bridge switch, through
back contact n to contact of battery key m² through key and from m¹ to
battery terminal b. Also from slide resistance terminal 72 to resistance at o¹
through resistance and from o² to galvanometer key contact d key..
Fig. 24. As detector or single galvanometer and battery. Circuit to be tested is
connected to terminals 2 and 3. Connection is then made through the instrument
from 2 to battery terminal a through battery B and from terminal to battery
key back contact m' through key and from contact m² back contact n of switch
through detector contact j to galvanometer terminal through galvanometer and
from terminal y through back contact d' of galvanometer key to terminal 3.
Fig. 25. As detector and rheostat. Circuit to be tested to be connected to
terminals 2 and 3. Connection is then made through the instrument from terminal 2
through contact k switch back contact g to battery terminal a through battery and
from through battery key m' and from contact m² through switch n and from
contact to wire resistance at 3 through the whole or part of resistance R off
contact to galvanometer terminal through galvanometer and from g' through
back contact of galvanometer key d to terminal 3.
Fig 26. As standard resistance. Circuit to be connected to terminals 3 and 4,
connection is then made through the instrument from 3 to back contact of
galvanometer key a' through galvanometer key and from contact d² to standard
resistance terminal o², through resistance and from o¹ to terminal 4.
Fig. 27. As galvanometer alone. Circuit to be connected to terminals 3 and 6
connection is then made through the instrument from 6 to back contact of battery
key m through key to back contact of switch, through switch N and from detector
contact j to galvanometer terminal 2 through galvanometer and from g¹ through
back contact of galvanometer key to terminal 3.
Fig. 28. As voltmeter. Circuit to be connected as in Figure 27 and connections
made through the instrument. in like manner but extra resistance can be inserted in
circuit at terminal 3 and galvanometer graduated to read E.M.F. (electro motive
force).

page_text: Fig. 29. As firing battery. Circuit connection is made to terminals 5 and 6
which are connected through to battery terminal 5 through battery to terminal 6
(these terminals are also used to charge battery when exhausted).
Fig. 30. As portable lamp. One terminal of lamp L is connected to lamp
switch through switch and from s to battery terminal a'. Other terminal of
lamp is connected to battery terminal a². Lamp L can be fixed in lid or to an
attachment on outside of box when portable light is required.
Fig. 31. As potentiometer. (1) Circuit connection is made to terminals 2 and 4
connection is then made from 2 through standard cell C to potentiometer key P and
from p to galvanometer terminal through galvanometer and from g² to sliding
contact on resistance R. Also from terminal 2 to resistance terminal through
resistance R and from 2 to terminal 4.
Fig. 32. As potentiometer. (2) Circuit connected to terminals 2 and 4 con-
nection is made through the instrument as in (1) through standard cell and
galvanometer to sliding contact ; also from 2 through potentiometer switch
contact and back contact 7 to battery terminal a. Also from 2 to slide wire
resistance contact through resistance R and from to bridge contact through
switch and from back contact N to battery contact M2 through key and from M
to battery terminal ; also from 2 to terminal 4.
Fig. 33. As potentiometer. (3) Circuit is connected to terminals 2 and 4
connection is made from 2 through the instrument to slide resistance terminal r
through resistance R and from to bridge contact 1, through switch and from n to
battery contact m² through key m to battery terminal . Also from resistance R
at to terminal 4, also from sliding contact through galvanometer to contact i of
potentiometer switch thence to p and from there to terminal a² of battery.
In the top of the box we fix a specially wound galvanometer (G) which is
connected from ' to ' thence to terminal 3 from g' to the potentiometer key pl;
also from g² to sliding contact over the resistance wire R from g₁ to i;
potentiometer contact from g² to detector contact j.
Referring to Fig. 22 the following indicate the connections.
Slide wire resistance. Connected through, to terminal 2; and to switch
contact being the nominal position of rest for the switch bar through ² to
terminal 4 and to standard resistance at o¹. Also, from to switch contact /.
Standard cell connected through to contact p2 and through c² to terminal 2.
Standard resistance connected through O¹ to and switch contact ; from O'
to terminal 1 and also contact .
Lamp switch S from S' to battery terminal a'; S' through lamp L to contact
battery terminal a².
Galvanometer key d to galvanometer terminal g', also to potentiometer key ';
through standard resistance and scale wire and galvanometer G; also to contact
potentiometer switch at through standard resistance and scale wire, and
galvanometer G also to terminal 3.
Contact to standard resistance O'; also to terminal 1.
Battery key to contact, the battery terminal
contact of switch N;
; also contact m² to back
Potentiometer switch P connected through contact 7 to battery terminal a³ ;
through contact k to slide wire terminal and also terminal 2; from contact i to
galvanometer terminal gland potentiometer key p'.
Also from contact i through galvanometer and slide wire to resistance O and
contact to galvanometer key d and terminal 3.
Bridge switch N. from back contact a to battery key m² contact / to standard
resistance terminal o' and slide wire terminal from contact j to galvanometer
terminal g, and slide contact h.
Battery from terminal a to negative terminal 5; also to lamp switch contact s¹
terminal a through lamp L to switch terminal S'; terminal &¹ to battery key back
contact m² and positive terminal 6.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. In means or apparatus for use in making clectrical tests the combination
or arrangement in one portable instrument or enclosure of the various instru-
mentalitics set forth, or the substantive portion thereof, with the electrical
connections therefor adapted to be selected and used according to requirement, all
as and for the purposes hereinbefore described.
2. The combination or arrangement in one compact portable case or instrument,
of various apparatus for use in electrical testing operations of various kinds;
including a battery, a galvanometer, a standard resistance, variable resistance
standard cell with suitable switches, keys and terminals (and an electric lamp if
required) so as to economise and effect combination of electrical connections,
substantially as set forth.
3. The combination of instrumentalities for use in performing electrical testing
operations of various kinds so arranged and combined that the parts required for a
particular operation and the connections therefor required may be separately
brought into use in manner and for the purposes substantially as hereinbefore
set forth.
Dated the 9th day of Nov 1801
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicants.