Year: 1889

page_text: We FRANCIS HENRY NALDER, HERBERT NALDER, CHARLES WILLIAM SCOTT
CRAWLEY and ALFRED SOAMES, all of the Firm of Nalder Brothers and Company,
of 132 Horseferry Road, Westminster, Electrical Engineers, 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 :-
Our invention has reference to instruments for measuring electricity known as
ammeters and voltmeters.
It consists in so arranging the piece generally called the cock-piece that carries
the pivot of the moving system that the pivot shall be in a vertical line passing
through the centre of the dial and that the instrument shall present a perfectly
symmetrical appearance notwithstanding that the pivot is excentric with regard to the
coil or solenoid. It is of great advantage for balancing to have the soft iron needle
and the pointer in the same straight line and this can always be done without injuring
the appearance of the instrument because the coil can be placed in any excentric
position with respect to the needle. We preferably have the pointer and the needle in
one plane passing through the axis of the needle and balance them; the sensibility of
the instrument then depends solely on the position of the gravity bob on its rod or on the
weight and length of the rod itself, or on the spring if a spring be employed; this is
a great convenience, especially in gravity instruments, when the instrument has
to be adjusted to read to any particular number of volts or ampères at the top of
the scale.
The invention further consists in forming the needle of one or more pieces of
soft iron wire set in a brass holding piece and secured therein by pinching this
piece. A very soft iron needle can easily be produced in this form; if the needle
is united to a holding piece by soldering, the heat tends to harden the iron.
The invention comprises the attachment of the bobbin to the face of the instrument
only, and for this purpose it may either be secured thereto by screws or be made in
one piece therewith. With this attachment of the bobbin to the face only the
fitting together of the parts of the instrument is very much simpler than when
the bobbin is attached to the base of the instrument as it has hitherto been.
whole of the case including the face is preferably made from a single spinning.
The

page_text: The accompanying drawings represent an instrument in which our improvements
are embodied. Figure 1 is a front view, Figure 2 a section on the line -x of Figure 1.
Figure 3 is a view of the "cock-piece" as seen from the back or under side and
with the pointer at the centre of the scale. Figure 4 is a partial side view of
the needle with its holding piece, pivot and pointer, and Figure 5 a plan of the
cock-piece.
b is
a is the base of the instrument formed of wood or other suitable material.
the metallic case and c the face, these parts being made from a single spinning dis
the bobbin which is shown as secured to the face c by screws. The bobbin is not
attached to the base a. e is the coil and ffare the terminals. g is the dial. A is the
cock-piece composed of a disc or plate with flange i extending around so much of it as
is not required for the play of the pointer; it is secured to the face c by screws and
when in place covers the opening through which the parts which it carries are inserted
in such a way as to present a perfectly symmetrical appearance, that is to say there is
no visible appearance of excentricity. kkare the points forming the pivot of the
moving system, the points being connected by a spindle or arbor ; this pivot is in a
vertical line passing through the centre of the dial, but is excentric with regard to the
coil e.
m is the soft iron needle and n the pointer; these are in one plane passing
through the axis or pivot k and they are balanced. is the gravity bob and g its rod
on which it is adjustable. The needle m is formed of three pieces of soft iron wire set
in a brass holding piece which is pinched so as to fix the wires. Three pieces of wire
are shown but the number of pieces is optional.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim in respect of instruments for measuring electricity is :-
1. Arranging the cock-piece so that the pivot of the moving system is in a vertical
line passing through the centro of the dial and excentric with regard to the coil
or solenoid while the instrument presents a perfectly symmetrical appearance sub-
stantially as set forth.
2. A needle formed of one or more pieces of soft iron wire set in a holding piece
and fixed by pinching the latter upon them as set forth.
3. Attaching the bobbin to the face of the instrument only, as set forth.
4. The improved instrument hereinbefore described.