Improvements in or relating to Dividers applicable for Demonstration of Mathematical and Analogous Problems.
Year: 1898

page_text: Date of Application, 22nd Apr., 1898-Accepted, 4th June, 1898
COMPLETE SPECIFICATION.
Improvements in or relating to Dividers applicable for
Demonstration of Mathematical and Analogous Problems.
the
We, FREDERICK HENRY DE TRAY and THOMAS RICHARD SLEDDING, of Quincy, in
the County of Adams and State of Illinois, United States of America, 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 relates to dividers designed for use by architects, draftsmen, sur-
veyors, civil engineers, professors of mathematics, and others, in the demonstration
of mathematical and analogous problems, the dividers being provided with suitable
scales, geometrical, and otherwise, and the members thereof being so constructed and
arranged as to adapt them for relative adjustment, such as to enable the operator to
avoid the loss of time ordinarily consumed in calculation, and at the same time attain
a desirable accuracy in measurement and proportion.
The object of our invention is to provide a simple and compact construction and
arrangement of parts including oppositely-extending long and short arms so mounted
as to enable the points of the short arms to lay off decimal parts of a unit of measure-
ment of which the points of the long arins indicate the unit, or a multiple thereof,
the relative adjustments of the long and short arms being such as to provide for
varying with accuracy the relation between the measurements laid off respectively by
the points of the long and short arms.
Further objects and advantages of this invention will appear in the following
description, and the novel features thereof will be particularly pointed out in the
appended claims.
In the drawings-
Figure 1 is a view of dividers constructed in accordance with our invention, show-
ing the members closed or in their norinal relative positions.
Figure 2 is a view showing the members spread for operation.
Figure 3 is a longitudinal sectional view on the plane indicated by the line 6-6 of
Figure 1.
Figure 4 is a detail view in perspective of the rack-bar and adjusting connections.
Figure 5 is a similar view of the latch.
Figure 6 is a detail sectional view of the interlocking members of the holding
devices on the line 3-3 of Figure 1.
Figure 7 is a detail view in perspective of one of the short arms.
Figure 8 is a face view of the quadrant-plates to show the co-operating scales
thereon.
Figure 9 is a perspective view of a gage adapted for accurately setting the long
arms with relation to the pivotal point of connection of the members.
Similar numerals of reference indicate corresponding parts in all the figures of the
drawings.
The members of the dividers embodying our invention consist of pivotally-con-
nected quadrant-plates 1 and 2, each of which carries a long arm 3 and a short arm 4,
the pivot 5, by which the quadrant-plates are connected, consisting of a bolt extend-
ing transversely through the plates at their reduced ends, and being arranged con-

page_text: centrically with the segmental faces 6, which consist of inturned flanges at the
outer edges of the plates. Carried by, and preferably formed integral with, the plates
are yokes 7 provided at their centers with sockets 8, in which are fitted the reduced
inner extremities of the removable long arms 3, said arms having cross-sectionally
angular reduced portions 9, fitting in correspondingly constructed portions of the
sockets, and also with extensions 10, fitting in reduced extensions of the sockets,
and engaged by thumb-screws 11, or equivalent fastening devices. The reduced
bearing-portions 9 of the arms allow longitudinal extension of the latter, to secure
the desired adjustment, in connection with a gage illustrated in Figure 9, and
consisting of a bar 12, suitably graduated to indicate linear measurements, having
fixed and adjustable heads 13 and 14, of which the latter is adapted to transverse
the scale, and is provided with a set-screw 15 to secure it at the desired adjust-
ment, and a fixed point 16, arranged at the initial point of the scale, for alinement
with the pivotal point of connection of the divider-members. By disposing the
extremity of the pivot upon the point 16, the adjustable head 14 having been
arranged previously at the desired adjustment, the contact of the extremities of the
long arms with the plates of the head 14 will indicate the proper position of the long
arms, whereas any interval between the points of the arms and the face of the
head 14 will indicate the necessity for adjustment of the long arms axially to
produce such contact.
In addition to the peripheral flanges 6 of the quadrant-plates, the latter are also
preferably provided with side flanges 17 to serve as means for protecting the parts
of the instrument which are located between the planes of the plates, and which
include the extensible short arms 4. These short arins are longitudinally slotted, as
shown at 18, and the pivot-bolt 5 extends through the slots of the short arms at their
point of registration, irrespective of the relative positions of the quadrant-plates. The
inner ends of the short arms are provided with guiding projections or bosses 19 fitting
in radial slots 20 in the quadrant-plates, and fitted upon said projections or bosses
beyond the faces of the quadrant-plates are double-armed pointers 21, which traverse
parallel scales 22 upon opposite sides of the slot, one of said scales preferably being
in accordance with the metric system of notation. The pointers 21, which are
provided with angular openings to receive the outer extremities of the correspond-
ingly constructed projections or bosses 19, are held in place by thumb-nuts 23 threaded
upon reduced stems, and this relative arrangement of parts insures the accurate
guiding of the inner ends of the short arms of the dividers in their radial adjustment
to secure the desired extension of the points. The short arms, at their points con-
tiguous to the pivot 5, operate in contact, and respectively through guide-openings
formed by the cut-away portions of the flanges 17 of the quadrant-plates. The
construction of points, which are preferably employed in connection with the short
arms, includes needles 24 fitting in contractible sockets 25, of tapered or conical
exterior construction, and the latter in turn fit in seats 26 formed in the ends of the
arms 4, said seats being inclined to bring the extremities of the needles approximately
into contact, or in the planes of the inner or contiguous surfaces of the arms. The
sockets 25 are also of longitudinally split construction, whereby, after the insertion
of a needle, the introduction of the socket into its seat causes the contraction of the
socket, and hence the secure locking of the needle in place at the desired adjustment.
Also, the expansion, or the resistance of the socket to contraction, serves to firmly
retain the socket in the seat 26.
The means disclosed in the drawings for adjusting or setting the members of the
dividers, and holding them during use at the desired adjustment include a segmental
rack or setting-bar 27, fitted in a cross-sectionally dovetailed guide 28 within the
quadrant-plate, or segmental-faced member 1 of the instrument, for linear adjustment,
said guide preferably consisting of a cross-sectionally dovetailed channel cut in the
inner surface of the plate. This rack-bar is provided in its periphery, preferably its
outer edge, with a series of spaced notches or seats 29 for engagement by a spur or
tooth 30 on a yielding latch 31, which is mounted preferably upon the face of the
said segmental-faced member 1. In the construction illustrated, this latch consists

page_text: of a plate-spring secured at one end, as by a screw 32, to the member, and terminating
in the above-described spur or tooth which extends inwardly through a suitable per-
foration 33 in the flange 6. Contiguous to its free end, however, this latch is provided
with an ear 34 which, in the construction illustrated, is arranged parallel and in
contact with the side surface of the plate 1, and is fitted with a thumb-hold 35 having
a stop-pin 36 which extends into a slot 37 formed in the plate, whereby the swinging
movement of the latch at its free end is limited, but at the same time is sufficient to
allow the disengagement of the spur or tooth 30 from the notches or seats of the
rack-bar when outward pressure is manually applied to the thumb-hold 35.
By means of the rack-bar and latch a coarse or approximate adjustment of
the members of the dividers may be attained without loss of time, but in order
that an accurate or nice adjustment thereof may be accomplished, we employ
feeding devices in connection with the rack-bar, and in the construction illustrated
these feeding devices include a feed-screw 38 swiveled in a suitable bracket 39 in the
member 2, and having a terminally exposed thumb-nut or hold 40; and a feed-nut or
block 41 into which said feed-screw is threaded, and which in turn is swiveled upon
the rack-bar by means of a screw 42, or its equivalent. The feed-nut is provided
concentric with its pivot-screw with a trunnion 43 which extends laterally through a
slot 44 in a guide plate or keeper 46, to the inner surface of the member 2.
Hence, after the coarse or approximate adjustment of the members of the dividers,
by the engagement of the latch with one of the notches of the rack-bar, thus
locking in a fixed relative position the member 1 and said rack-bar,. the feed-screw
may be operated, by turning the thumb-nut or hold 40, to vary the position of the
rack-bar in its guide, and hence of the member 1 with relation to the member 2.
We have also found it desirable, in a device of this class, to provide means for
insuring the proper relative swinging movements of the segmental-faced
members and 2, and in order to accomplish this we provide an interlocking joint,
between said members contiguous to their segmental faces, such interlocking
connection in the construction illustrated, including an inturned lip or tongue 47
on one of the members fitting in a groove or channel 47° in the other member,
this interlocking connection being continuous throughout the lengths of the
segmental faces. Obviously, as the segmental faces extend for a considerable
distance upon each side of the lines of the divider-arms, the members of the
interlocking joint remain in engagement in all adjustments of the divider-members,
and thus insure an accurate relative arrangement of the extremities of the long
arms, and relieve the pivot-pin 5 of transverse strain. The extent of angular
adjustment of the divider-members is indicated by the co-operative scales formed
on the faces 6.
It will be understood that, while our description and drawings have set forth
the preferred embodiment of our invention, including suitable means of adjustment
for securing that accuracy in relative arrangement which is desirable in instruments
designed for use in connection with mathematical calculations, various changes in
the form, proportion, and the minor details of construction may be resorted to
without departing from the spirit or sacrificing any of the advantages of this
invention.
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 is:-
1. Dividers having pivotally-connected members carrying long and short arms,
and provided with segmental scales concentric with the pivot of the members,
substantially as specified.
2. Dividers having pivotally-connected segmental-faced members carrying long
arms and extensible short arms, substantially as specified.
3. Dividers having pivotally connected members provided, concentric with their
pivot, with a segmental interlocking joint, and carrying long and short armis,
substantially as specified.

page_text: 4. Dividers having pivotally-connected members provided, concentric with their
pivot, with a segmental interlocking connection consisting of a lip or tongue on one
of the members permanently engaging a channel in the other member, said members
carrying long and short arms, substantially as specified.
5. Dividers having pivotally-connected members carrying long and short arms,
and provided, concentric with their pivot, with segmental interlocking guiding
devices extending in opposite directions from the lines, and in the planes of, the
arins, substantially as specified.
6. In dividers, the combination of quadrant-members, a pivot-bolt connecting the
members, long arms carried by, and occupying fixed relations to, the quadrant-
members, short arms slidably fitted upon the quadrant-members, radially with
relation to the pivot-bolt, means for indicating the lateral adjustment of the quadrant-
members and arms, and means for indicating the slidable adjustment of the short
arms, substantially as specified.
7. In dividers, the combination with pivoted quadrant-members, and long arms
movable therewith, of short arms slidably fitted to the respective quadrant-members
to occupy normal axial relation to said long arins, and locking devices each mounted
on one quadrant-member and operatively connected with the short arm fitted
thereto, substantially as specified.
8. In dividers, the combination with flanged quadrant-members, a pivot-bolt, long
and short arins mounted on the respective quadrant-inembers, a setting bar housed
within said flanged quadrant-members, and an adjusting-screw connected to one end
of the setting-bar and to one of the quadrant-members, and means on the other
quadrant-member for engagement with the setting-bar, substantially as specified.
9. In dividers, the combination with pivoted quadrant-members carrying arms,
a two-part setting bar having a feed-screw mounted upon one of the quadrant-
members for communicating linear movement to the other bar-member, and means
carried by the other quadrant-member for engaging the adjustable bar-member,
substantially as specified.
10. In dividers, the combination with quadrant-members provided with guides,
and short arms slidably fitted in said guides, of a pivot-bolt connecting said members
and passing through said short arms, means for locking the short arms at the desired
extension, and long arms carried by the quadrant-members, substantially as
specified.
11. In dividers, the combination with quadrant-members having guides, of
extensible short arms slidably fitted in said guides, pointers movable with said short arms
and traversing scales on the quadrant-members, means for securing the short arms at
the desired adjustment, and long arms carried by the quadrant-members, substantially
as specified.
12. A pair of dividers comprising quadrant-plates or members having scales on
their segmental edges, long arms carried by said plates, short arins slidably connected
to the plates, a single pivot-bolt connecting the plates and extending through
longitudinal slots in the short arms, locking devices for securing the short arms
at the desired extension, and a setting device having members connected respectively
to the said plates or members, substantially as specified.
13. Dividers having pivotally-connected segmental-faced plates or members
carrying long arms, extensible short arms mounted to slide respectively upon the
plates or members, and provided with projections operating in radial slots therein,
pointers adjustably mounted upon said projections to traverse scales parallel with
the slots in the plates or members, and common locking devices for holding the
pointers in place and securing the short arins in their adjusted positions, substantially
as specified.
14. Dividers having pivotally-connected segmental-faced plates or members
provided with radial slots and carrying long arins, extensible short arms mounted
to slide upon the plates or members and having augular projections extending
through said radial slots, pointers having openings fitted upon said projections to
traverse scales on the exterior surfaces of the plates or members parallel with

page_text: the slots therein, and thumb-screws threaded upon extensions of said projections
to clamp the pointers upon the surfaces of the plates or members and secure the
short arms in their adjusted positions, substantially as specified.
15. Dividers having pivotally-connected arm-carrying plates, a setting-bar carried
by one of the plates and provided with spaced seats, and a latch carried by the other
plate and provided with a spur or tooth to engage said seats, substantially as
specified.
16. Dividers having pivotally-connected arm-carrying plates, a setting-bar having a
member adjustably mounted upon one of the plates, and provided with spaced seats,
and a latch carried by the other plate and having a spur or tooth to engage said seats,
substantially as specified.
17. Dividers having pivotally-connected arm-carrying plates, a segmental setting-
bar mounted upon one of the plates for adjustment concentric with the pivot thereof
and having spaced seats, and a latch carried by the other plate and having a spur or
tooth to engage said seats, substantially as specified.
. 18. Dividers having pivotally-connected arm-carrying plates, a segmental setting-
bar mounted upon one of the plates for adjustment concentric with the pivot thereof
and provided with spaced seats, and a latch consisting of a spring fitted upon the
other plate and provided with a spur or tooth, to engage the seats of the setting-bar,
and an exposed thumb-hold and a stop for limiting the swinging movement of the
latch, substantially as specified.
19. Dividers having pivotally-connected arm-carrying plates, a setting-bar having a
member mounted upon one of the plates for sliding movement, and also having a
swiveled feed-screw, and a pivotal feed-nut mounted upon said sliding member and
engaged by the feed-screw, and a latch carried by the other plate for engaging said
sliding-member, substantially as specified.
20. Dividers having pivotally-connected arm-carrying plates, and setting devices
including a rack-bar mounted upon one of the plates for sliding movement concentric
with the pivot of the plates, a slotted guiding keeper, a swiveled feed-screw, and a
feed-nut pivotally mounted upon the rack-bar, engaged by said feed-screw, and
having a trunnion mounted in the slot of the keeper, and a latch carried by the other
plate for engagement with the seats of the rack-bar, substantially as specified.
21. Dividers having pivotally-connected plates or members, and means for securing
the same at the desired angular adjustment, yokes carried respectively by the plates
or members and provided with sockets alined with the pivotal point of the plates or
members, short arms carried by the plates or members, long arms fitted respectively
to slide in said sockets, and securing devices for fastening the long arms at the
desired adjustment, substantially as specified.
22. Dividers having its arms provided with tapered seats, and tapered contractible
needle-holding sockets fitting in said seats, substantially as specified.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicants.