Improvements in or relating to Combined Astatic and Dead Beat Galvanometers, especially for Use on Board Ship.
Year: 1896

page_text: Date of Application, 1st May, 1896
Complete Specification Left, 29th Jan., 1897-Accepted, 6th Mar., 1897
Improvements in or relating to Combined Astatic and Dead Beat
Galvanometers, especially for Use on Board Ship.
I, THOMAS CLARK of 66 Jerningham Road, Hatcham, London, S.E.
Electrician, do hereby declare the nature of this invention to be as follows:-
This invention relates to galvanometers of any suitable character-especially
for use at sea-in which a dead beat or damping effect is produced or a damper
used as for instance in galvanometers such as described in my application (jointly
with Thomas Edwin Weatherall) for Patent dated 2nd November 1894,
No. 21013.
Now my present invention consists in combining with the damper suitable magnets
mounted in any suitable manner thereon advantageously at the extreme ends of
said damper but according to my present invention the damper must be of such a
size or the position of these magnets thereon must be such that said magnets will
respectively be in a suitable position relative to the position of the coils and these
said magnets are magnetised in opposite directions i.e. as opposite poles.
Two such oppositely magnetised magnets will usually be found sufficient for
obtaining the object of my present invention i.e. one at each end of the damper.
Four coils (or other suitable number of coils) may be used as in the well-
known shore astatic galvanometer-a suitable opening being left between the top
and bottom coils for the mirror space; or my present improvements may be
applied to or arranged and mounted in-the galvanometer in any other suitable
manner.
By this invention when alteration of the direction of the ship's head takes place
the shifting of the zero of the instrument is obviated i.e. the needle (or equivalent)
of the instrument will not be deflected from such cause but remains at zero while
the ship swings or turns completely (or partly) round.
Furthermore by this invention the instrument acts much better and is made
very much more sensitive than the ordinary shipboard galvanometer heretofore
in use.
In such instruments for use at sea it is very important that means should be
provided for controlling and adjusting the instrument and counteracting or
controlling the influences which necessarily exist on board ship and the provision
of such means constitutes an important part of my present invention as follows:-
1. For choking or damping the effect of the earth's magnetism from or upon
the instrument (i.e. from or upon the controlling and system magnets etc.) I provide
rings bands or devices to completely encircle or surround the coils for instance one
such ring or device to completely surround the top pair of coils and another such
device to similarly surround the bottom pair of coils and either or both of these
magnetic damping rings may advantageously be adjustable vertically or otherwise
for instance the top damping ring or rings may have mounted thereon a cross-head
or frame of brass or non-magnetic material by which same is suspended (within the
casing) and any suitable adjusting device arranged to raise and lower same for
instance a screw (with milled head) passing loosely through a fixed guide or
support on the casing and screwing into an internally screw-threaded socket or
hole in said frame or cross-head supporting said damping ring-a set screw being
Price 8d.1.
.

page_text: also advantageously arranged to bind or hold said adjusting screw in the required
position.
These damping rings or devices are of soft annealed iron suitable for the purpose
of choking or damping the earth's magnetism or protecting the instrument from
the latter and may be of sufficient size thickness depth or shape for this purpose
and if desired instead of using one ring only in each case any number of same may
be used concentric or otherwise.
Instead of making the lower damping ring or rings adjustable (or in addition
thereto) I may provide means for raising or lowering the astatic system bodily
with respect to the coils so as to obtain a very fine and accurate degree of magnetic
balance cr adjustment and for this purpose I may use a pivoted lever on one end of
which rests or is connected to-the bottom of the astatic system and a very fine
threaded screw (with an adjusting-nut or milled head) on or connected to the other
end of said lever whereby a very very fine adjustment can be had.
2. Movable control magnets are arranged oppositely opposed on opposite sides
of the coils (the south pole of the control magnet in each case being proximate to
the north pole of the astatic system magnet and vice versa) and meaus provided for
causing them to simultaneously and equally approach towards or recede from the
astatic system thereby decreasing or increasing the co-efficiency of the instrument
as required.
3. The centre of each coil may have a hollow core for the insertion of soft iron
either in a bundle of wire or in other form to increase the co-efficiency of the
instrument as desired.
The ordinary zero adjusting magnet may be fixed in any suitable position within
the aforesaid soft iron rings.
Dated this 1st day of May 1896.
Improvements in or relating to Combined Astatic and.Dead Beat
Galvanometers, especially for Use on Board Ship.
1, THOMAS CLARK of 66, Jerningham Road, Hatcham, London, S.E.
Electrician, 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 :-
This invention relates to galvanometers of any suitable character especially
for use at sea-in which a dead beat or damping effect is produced or a damper
used as for instance in galvanometers such as described in ny application (jointly
with Thomas Edwin Weatherall) for Patent dated 2nd November 1894
No. 21043.
Now my present invention consists in combining with the damper suitable
magnets mounted in any suitable manner thereon advantageously at the extreme
ends of said damper but according to my present invention the damper must be of
such a size or the position of these magnets thereon must be such that said magnets
will respectively be in a suitable position relative to the position of the coils and
these said magnets are magnetised in opposite directions i.e. as opposite poles.
Two such oppositely magnetised magnets will usually be found sufficient for
obtaining the object of my present invention i.e. one at each end of the damper..
Four coils (or other suitable number of coils) may be used as in the

page_text: well-known shore astatic galvanometer-a suitable opening being left between the
top and bottom coils for the mirror space; or my present improvements may be
applied to or arranged and mounted in-the galvanometer in any other suitable
manner.
By this invention when alteration of the direction of the ship's head takes place
the shifting of the zero of the instrument is obviated or so greatly reduced as to
be practically obviated i.e. the needles (or equivalent) of the instrument will not
be deflected from such cause but remain at zero or practically at zero while the
ship swings or turns completely (or partly) round.
Furthermore by this invention the instrument acts much better and is made
very much more sensitive than the ordinary shipboard galvanometer heretofore
in use.
In such instruments for use at sea it is very important that means should be
provided for controlling and adjusting the instrument and counteracting or
controlling the influences which necessarily exist on board ship and the provision
of such means constitutes an important part of my present invention as follows:-
1. For choking or damping the effect of the earth's magnetism from or upon the
instrument (i.e. from or upon the controlling and system magnets, etc.) I provide
rings bands or devices to encircle or surround the coils for instance one such ring
or device to completely surround the top pair of coils and another such device to
similarly surround the bottom pair of coils and either or both of these magnetic
damping rings may advantageously be adjustable vertically or otherwise for instance
the top damping ring or rings may have mounted thereon a cross-head or frame of
brass or non-magnetic material by which same is suspended (within the casing)
and any suitable adjusting device arranged to raise and lower same for instance a
screw (with milled head) passing loosely through a fixed guide or support ou the
casing and screwing into an internally screw-threaded socket or hole in said frame
or cross-head supporting said damping ring-a set screw being also advantageously
arranged to bind or hold said adjusting screw in the required position.
These damping rings or devices are of soft annealed iron suitable for the purpose
of choking or damping the earth's magnetism or protecting the instrument from
the latter and may be of sufficient size thickness depth or shape for this purpose
and if desired instead of using one ring only in each case any number of same may
be used-concentric or otherwise.
Instead of making the lower damping ring or rings adjustable (or in addition
thereto) I may provide means for raising or lowering the astatic system bodily
with respect to the coils so as to obtain a very fine and accurate degree of magnetic
balance or adjustment and for this purpose 1 may use a pivoted lever on one end of
which rests or is connected to the bottom of the astatic system and a very fine
threaded screw (with an adjusting nut or milled head) on or connected to the other
end of said lever whereby a very very fine adjustment can be had.
2. Movable control magnets are arranged oppositely opposed on opposite sides of
the coils (the south pole of the control magnet in each case being proximate to the
north pole of the astatic system magnet and vice versa) and means provided for
causing them to simultaneously and equally approach towards or recede from the
astatic system or coils thereby decreasing or increasing the co-efficiency of the
instrument as required.
If desired either above or below the poles of these control magnets (or in lieu
of the latter) and in a position to intercept some of the lines of force between the
system magnets and the aforesaid control magnets there may be placed a magnet
or magnets adjustable or otherwise singly or in pairs so arranged as to give a ready
means of rendering the system magnets astatic or alternatively or in addition to
the foregoing a soft iron body or bodies may be arranged to obtain the same
result.
3. The centre of each coil may have a hollow core for the insertion of soft iron
either in a bundle of wire or in other form to increase the co-efficiency of the
instrument as desired.
"

page_text: '
The ordinary zero adjusting magnet may be fixed in any suitable position within
the aforesaid soft iron rings.
Referring to the accompanying drawings which illustrate a galvanometer
according to my present invention:-
Fig. 1 is a front elevation of the instrument without any of the "adjustments
shown therein.
Fig. 2 is a front view of said jacket detached from the instrument with the slide
shown therein in dotted lines.
Fig. 3 is side elevation of Fig. 2.
Fig. 4 is side elevation of the instrument i.e. at right angles to Fig. 1 the same
parts being removed as in Fig. 1.
Fig. 5 is a plan of the instrument-the same parts being removed as in Figs. 1
and 4.
Fig. 6 is a local view of the back of the coils showing adjustable control magnets
and means of adjusting same.
Fig. 7 is a local plan view of the said means for adjusting the said control
magnets.
Fig. 8 is a plan of the upper damping ring and its means of supporting and
vertically adjusting same, Fig. 9 being a view of the same in elevation, and Fig. 10
a local view of the screw by which same is adjusted and locked in position.
Fig. 11 is a plan of the mechanism below the instrument used for raising or
lowering the astatic system bodily.
Fig. 12 is a side elevation of said mechanism shown in Fig. 11-applied to the
vulcanite base B.
Similar letters of reference indicate corresponding parts throughout.
A is the base or pedestal for instance mahogany on which the instrument is
mounted.
B is disc or plate of vulcanite or other suitable insulating material.
CC are the coils carried on the uprights or supports D fixed to the plate B.
E is space provided between the coils C for the jacket F (Figs. 2 and 3) to
fit into.
G is the slide which is constructed and arranged within said jacket in a similar
manner to that described in the said Patent No. 21043 of 1894 only according to
my present invention two separate and oppositely magnetised magnets G₁ are
provided on the "damper" G* towards the extreme ends thereof at a distance apart
equal to the distances of the centres of the coils and coinciding with said centres
-as shown.
G' is the ordinary mirror.
H H are the adjustable control magnets arranged on opposite sides of the
coils C.
HH' are movable arms carrying said magnets H H at the outer ends thereof
while the inner end of each said arm has a flange H2 thereon with a screw-threaded
opening therethrough through which the adjusting screw I passes.
Said adjusting screw 1 is formed with a right and left handed screw thread
thereon while about midway of the length of said screw I same is journalled in
the bearing J fixed to the frame of the instrument a collar I¹ being fixed on said
screw I on either side of said bearing J so as thus to hold said screw in position
but free to be revolved.
Thus it will be seen that by turning the milled head 1* in one direction thereby
the two arms Hand with same the magnets H H are simultaneously caused to
approach the coils C and by turning said milled head 1* in the opposite direction
thereby said magnets are simultaneously moved away from said coils C.
Lis the case or cover enclosing the coils C etc.
M is upper damping ring, and
N is lower damping ring.
33

page_text: (see Fig. 10) this latter passes up through the top of the case L and is screw-...
threaded and has the milled nut Q thereon by revolving which latter said pin is
raised or lowered and thus the damping ring Mis raised or lowered and when thus
adjusted as desired can be there fixed by a set screw or otherwise held or adjusted
as desired.
The lower damping ring N may be made adjustable in any desired manner-for
instance simply by screw clumps or set screws (not shown) passed through or
otherwise secured to the case L.
It will thus be seen that these damping rings M and N respectively encircle
the coils C and are adjustable relatively thereto as and for the purposes
hereinbefore specified.
R is lever. pivotted at R' to a bearing S fixed to the base B or other fixed part
of the instrument and at one end of this arm or lever R same is acted on by the
screw T with milled head T¹ thereon this screw being screwed through the fixed
bridge U attached to the base or some fixed part of the instrument.
When the pivotted lever R (see Figs. 11 and 12) is thus depressed at one end.
by the screw T it follows that the other end Rx of said lever R is thereby elevated
and is so formed and arranged that this said end R* comes directly under and
against the lower end of the jacket F (Fig. 2) below the coils C and thus a very
delicate adjustment of the said jacket and the "system" therein is obtained.
The lever R is of such a length and so arranged as to extend to a couvenient
point (advantageously outside the case L) for the milled head T¹ to be operated.
If desired other equivalent or suitable means may be used for adjusting the astatic
system bodily as aforesaid.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I.
claim is :-
1. In galvanometers of the character described-the arrangement and com--
bination therein of four or more coils such as C with two or more magnets such
as G'on a damper or damping device such as G* the latter being suspended at both
ends and either with or without means to adjust the slide containing said damper
vertically substantially in the manner and for the purposes hereinbefore set forth.
2. In galvanometers of the character described-the arrangement and com--
bination therein of four or more coils such as C and damping rings or devices such
as M and N adapted to be adjusted relatively to said coils C substantially in the
manner and for the purposes hereinbefore set forth.
3. In galvanometers of the character described-the arrangement and com-
bination therein of four or more coils such as C with two or more magnets such
as G' on a damper or damping device such as G* the latter being suspended at
both ends and damping rings or devices such as M and N adapted to be adjusted
relatively to said coils C substantially in the manner and for the purposes
hereinbefore set forth.
4. In galvanometers of the character described-the arrangement and com-
bination therein of two or more control magnets such as H and H* mounted on
independent supports and means to cause same to simultaneously and equally
approach towards or recede from the coils C substantially in the manner and for
the purposes hereinbefore described.
5. In galvanometers of the character described-the arrangement and com-
bination therein of four or more coils such as C with two or more magnets such
as G' on a damper or damping device such as G* the latter being suspended at
both ends and damping rings or devices such as M and N adapted to be adjusted
relatively to said coils C and two or more control magnets such as H and H*
mounted on independent supports and means to cause same to simultaneously and
equally approach towards or recede from the said coils C substantially in the
manner and for the purposes herein before set forth.
6. Galvanometers constructed and operating substantially in the manner and

page_text: for the purposes herein before described and illustrated in the drawings hereunto
annexed.
Dated this 28th day of January 1897.
TONGUE & BIRKBECK,
Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.