Improved Means for Facilitating the Adjustment of Compasses, Protractors, and similar Instruments.
Year: 1890

page_text: Date of Application, 29th Sept., 1890
Complete Specification Left, 29th June, 1891-Accepted, 29th Sept., 1891
PROVISIONAL SPECIFICATION.
Improved Means for Facilitating the Adjustment of Compasses,
Protractors, and similar Instruments.
I, EDWIN OADES, of Wokingham, in the County of Berks, Auctioneer and
Surveyor do hereby declare the nature of this invention to be as follows:-
My invention relates to the adjustment of compasses, protractors and similar
instruments and comprises the improvements hereinafter set forth.
An important feature of my said invention consists in the provision of improved
means for effecting the fine adjustment of a compass or instrument for measuring
distances, the coarse adjustment thereof having been previously made by hand in
the usual manner.
My said invention is also advantageously applicable to calipers, protractors or
devices for laying down or measuring angles, and to similar instruments.
In carrying my said invention into practice I provide a compass having a third.
or supplementary leg. Two of the said legs are formed of corresponding lengths
and with suitable points, and the third or supplementary leg is formed shorter than
the other two. The said short or supplementary leg is placed on the outside and
is provided with a curved bar or quadrant passing through suitable holes provided
in the other or long legs of the said compass, which latter are so arranged to be
capable of sliding or moving freely thereon. The outside long leg of the said
compass, or that furthest from the said short or supplementary leg thereof, is
provided moreover with a thumb screw adapted to engage in one or other of holes
or recesses in the said curved bar or quadrant, or with other suitable means for
securing or fixing the said leg upon the quadrant and, thus maintaining the said
long leg firmly in position at any desired distance apart from the short or
supplementary leg. The middle long leg or that nearest to the short or supple-
mentary leg to which the quadrant is secured, is so arranged in combination with
the said short or supplementary leg that it can be moved for fine dividing by means
of a slide block or plate arranged to slide freely thereon and by a Vernier plate
having a Vernier scale and connected with the said slide block by means of a
suitable micrometer screw. A thumb or clamping screw or other means is provided
for locking or securing the said slide block in position whilst the fine adjustment of
the Vernier plate is effected by means of the said micrometer screw. I provide
moreover, a suitably graduated scale upon the middle long key or that nearest the
above mentioned short or supplementary leg. The adjacent edges of the said legs,
or of either of them against which the said slide block and Vernier plate bear are
formed slightly inclined inwards or towards the pivot point, so that any movement
of the slide block on the short or supplementary leg or of the Vernier plate
through the micrometer screw, will tend to move or adjust the said long leg
relatively to the said short or supplementary leg, and consequently also relatively
to the other long leg.
When intended for use as a calipers I sometimes provide the said long legs with
suitable rearward extensions.
In using a compass filled with my improved means for facilitating adjustment, the
coarse measurement is first made in the usual manner, and the outer long leg or
that further from the herein before mentioned short or supplementary leg, is clamped
in position by means of the thumb screw, and the curved plate or quadrant. The
above mentioned slide block is then shifted so as to further adjust the inner long
leg or that nearest to the short or supplementary leg, relatively to the other or
outer long leg, the final adjustment thereof being effected by operating or moving
the Vernier plate through the micrometer screw. The coarse adjustment or

page_text: distance apart of the said long legs is read off the said curved bar or quadrant.
The amount of adjustment of the said long leg through the said slide block is read
off upon the herein before mentioned-scale upon the inner long leg, or that nearest
to the short or supplementary leg, which scale may be arranged to subdivide each
division on the scale on the curved bar or quadrant any suitable number of times,
and the final adjustment of the said leg through the Vernier plate is read off on the
Vernier scale in the usual manner. The said Vernier scale may be arranged to
subdivide each division upon the scale on the said middle long leg, or legs nearest
to the short or supplementary leg, into any convenient number of parts.
I thus provide for a very fine and accurate adjustment of the long legs of the
compass relatively to each other, thereby rendering the latter extremely
advantageous for use in work requiring great accuracy.
In applying my said invention to a protractor for laying down or measuring angles
upon paper I provide the said protractor with suitable arms connected or jointed
thereto in any well known manner at the point where the notch, nick, or hole
for setting the latter is situated, and so that the said notch, nick, or hole will
be in the centre of the said pivot point. One of these arms is formed longer than
the other arm, and is provided with a suitable point for facilitating the setting
thereof upon a drawing or the like. The said pointed or long arm is provided with
a suitably graduated scale, and the other or short arm is fitted with a slide block,
and a Vernier plate having a Vernier scale thereon, and adapted to be operated by
means of a micrometer screw in a manner similar to that hereinbefore described, for
the fine adjustment of one of the said arms relatively to the other. The protractor
moreover is suitably divided for coarse adjustment and is provided with holes or
recesses with one or other of which a pin mounted upon the short arm is adapted to
engage, or a thumb screw, or other suitable means is provided for securing the said
arm firmly in position whilst the fine adjustment of the other arm is being effected.
In order to admit of the adjustment of the protractor upon the drawing or the like
I cut away a portion of the pivot and form a notch, nick, or hole in the remaining
portion thereof in the usual manner. The hereinbefore mentioned arms are so
arranged that when in a position at right angles to the base of the protractor the
outer edge of the long or pointed arm, and the apex of the said point, will be in
line with the said notch, nick or hole and with 90 upon the scale. The said outer
edge moreover is preferably suitably bevelled.
It will be readily understood that by obvious modifications my improved means
for facilitating adjustment is also advantageously applicable to other measuring
instruments as for instance gauges and the like.
Moreover although I have hereinbefore described a convenient and advantageous
method of carrying my said invention into practice it is obvious that I can
somewhat modify the construction of my improved means for facilitating the
adjustment of compasses, protractors and similar instruments without however in
any way departing from the nature of my said invention. For instance, instead of
forming the adjacent edges of the said legs, or of either of them inclined inwardly,
as hereinbefore mentioned I sometimes provide a projection upon the Vernier plate
adapted to engage in a slanting groove in the long leg, or other leg, or I otherwise
arrange the said slide block and Vernier plate so that any movement thereof will
tend to adjust the said legs relatively to each other.
In some instances when the Vernier scale is arranged for very minute subdivision
of the hereinbefore mentioned scale upon the long leg, or other leg, I provide a
suitable magnifying glass which may be carried by a small bracket fixed to the
hereinbefore mentioned slide block.
Dad him oath 1
1000

page_text: COMPLETE SPECIFICATION.
Improved Means for Facilitating the Adjustment of Compasses,
Protractors, and similar Instruments.
I, EDWIN OADES, of Wokingham Berks, Auctioneer and Surveyor, 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 relates to the adjustment of compasses, protractors, and similar
instruments and comprises improvements hereinafter set forth.
An important feature of my said invention consists in the provision of improved
means for effecting the fine adjustment of a compass or instrument for measuring
distances. The coarse adjustment thereof having been previously made in the
usual manner.
My said invention may also be advantageously applied to calipers, protractors or
devices for laying down or measuring angles, and to similar instruments.
In the accompanying drawing I have shown how my said invention may be con-
veniently and advantageously carried into practice.
Figure 1 is an elevation of a pair of compasses or calipers provided with my
improved means for effecting the fine adjustment of the same.
Figure 2 shows my adjusting device as applied to a protractor for laying down
or measuring angles upon paper.
Figure 3 is a cross section on the line xx of Figure 1, and
Figure 4 is an end view of the sliding block.
Similar letters of reference indicate corresponding parts in the figures of the
drawing.
Referring to Figure 1 a and b indicate the legs of a pair of compasses which are
pivoted at a* and provided with suitable points for measuring and marking off
distances. On the outside of the leg a is arranged a third or supplementary leg c
which is also pivoted at a* in any convenient manner, and which is made shorter
than the legs a and b. The said leg 6 is provided with a curved bar or quadrant c¹
which is formed therewith or secured thereto and which passes through suitable
holes provided in the legs a and c, the latter being so arranged as to be capable of
sliding or moving freely on the said quadrant. The leg c of the said compass, is
moreover provided with a thumb screw b¹ adapted to engage in one or other of a
series of holes or recesses c2 in the said curved bar or quadrant or the said leg may
be provided with other suitable means for securing or fixing it upon the quadrant
and thus maintaining the leg firmly in any position at which it may be set. On
the short leg c I mount, so as to be capable of sliding thereon, a block d. This
block is provided with a Vernier plate d' on which is formed a projecting lug
which carries a pin or projection adapted to engage in a longitudinal groove. a²
provided in the leg a. It is obvious from this construction that by moving the
block d up and down the leg c, the leg a is adjusted nearer to or further from the
said leg c. For still finer adjustment I provide for moving the Vernier plate by
means of a fine micrometer screw d³, which also serves for keeping the Vernier
plate din contact with the inside of the leg c. The leg c is provided on the inside
edge with a suitable graduated scale, the corresponding edge of the Vernier plate
being also provided with a graduated scale in the usual manner.
A thumb or
clamping screw * or other suitable means is provided for locking or securing the
said slide block d in position on the leg c whilst the fine adjustment of the Vernier
plate d' is effected by means of said micrometer screw d³.
When the instrument is intended for use as calipers I sometimes provide the
said long legs with suitable rearward extensions e e¹.
In applying my said invention to a protractor f Figure 2 for laying down the

page_text: measuring angles upon paper, I provide the said protractor with suitable arms a
and c connected or jointed thereto in any well known manner at the pivot a where
the notch a³ for setting the latter is situated and so that the said notch will be in
the centre of the said pivot a*. The arm a is preferably bevelled on the outer
edge and is provided with a suitable point a for facilitating the setting thereof
upon a drawing or the like. The short arm c is provided with a suitably graduated
scale c and is fitted with a slide block d and a Vernier plate d' having a Vernier
scale thereon, and adapted to be operated by means of a micrometer screw d³
substantially in the manner described with reference to Figure 1. The pro-
tractor moreover is suitably divided for coarse adjustment and is provided with
holes or recesses f' with which a thumb screw, b' or a pin or the like in the said
arm c is adapted to engage, so as to secure the said arm firmly in position whilst
the fine adjustment of the other arm is being effected. In order to admit of the
adjustment of the protractor upon the drawing or the like I cut away a portion of
the pivot a* at us and form the notch a³ in the remaining portion thereof in the
usual manner. The arms a and c are so arranged that when in a position at right
angles to the base of the protractor the outer edge of the pointed arm a and the
apex of the point at will be in line with the said notch a³ and with the division 90,
on the protractor.
In using or manipulating a compass fitted with my improved means for facilitating
adjustment, the coarse measurement is first made by separating the points of the
legs a and b to approximately the distance required, in the usual manner, the leg c
being then clamped to the quadrant el by means of the thumb screw 6'. The slide
block d is then shifted so as to further adjust the leg a relatively to the leg b, the
final adjustment thereof being effected by operating the Vernier plate by means of
the micrometer screw (1³.
a
The adjustment or distance apart of the said legs a and b is read off on the said
curved bar or quadrant c'. The amount of adjustment of the said leg a effected
through the said slide block, is read off upon the scale c' on the leg c which scale
may be arranged to subdivide each division on the scale on the curved bar or
quadrant any suitable number of times, and the final adjustment of the said leg
which is made by means of the Vernier plate d', is read off on the Vernier scale d
in the usual manner. The said Vernier scale may be arranged to subdivide each
division upon the scale c¹ on leg c, into any convenient number of parts. I thus
provide for a very fine and accurate adjustinent of the long legs or operating legs
of the compass relatively to each other thereby rendering the latter extremely
advantageous for use in work requiring great accuracy.
It will be obvious that by suitably modifying my improved means for facilitating
adjustment, the same can be advantageously applied to other measuring instruments
such as gauges and the like, for instance, my improved instrument may consist of a
frame provided with two cross bars carrying a Vernier block substantially in the
manner described with reference to Figures 1 and 2 for accurately measuring or
gauging rods, bars, plates and the like.
Moreover although I have herein before described a convenient and advantageous
method of carrying my said invention into practice it is obvious that I can somewhat
modify the same in detail without however in any way departing from the nature
of my said invention. For instance, instead of forming a projection upon the
Vernier plate adapted to engage in a groove in the long leg or other leg, f some-
times arrange that the edge of the legs a adjacent to the ernier shall be inclined
inwardly and the Vernier shall be in contact with the said inclined edge or I
otherwise arrange the said slide block and Vernier plate so that any movement
thereof will tend to adjust the said legs relatively to each other.
In some instances when the Vernier scale is arranged for very minute subdivision
of the hereinbefore mentioned scale upon the leg provide a suitable magnifying
glass which may be carried by a small bracket fixed to the hereinbefore mentioned
slide block.

page_text: 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 :-
First. A compass or caliper provided with means for effecting the adjustment of
one leg relatively to the other and for ascertaining the amount of such adjustment
substantially as, and for the purpose, set forth.
Second. A protractor for laying down and measuring angles provided with a
radial arm and with means for effecting the fine adjustment of the said arm and for
ascertaining the amount of such adjustment substantially as, and for the purpose
set forth.
Third. The improved devices for measuring distances or angles constructed and
arranged substantially as described with reference to the accompanying drawing.
Dated this 29th day of June 1891.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.