Year: 1888

page_text: Date of Application, 16th Nov., 1888
Complete Specification Left, 29th Jan., 1889
Complete Specification Accepted, 2nd Mar., 1889
I, THOMAS GREEN, of 651 Christy Street, in the City of Davenport, County of
Scott, and State of Iowa, United States of America, do hereby declare the nature of
this invention to be as follows :-
This Invention relates to a measuring and drawing instrument specially adapted for
mechanics and to be used as inside and outside calipers, dividers, etc.
The improved instrument comprises a nearly circular graduated plate over which
moves a double index arm consisting of a pair of quadrant-shaped arms pivoted upon
a central hub of the plate at opposite sides thereof, the quadrants being united at
their periphery so as to embrace and fit closely to the periphery of the graduated arc.
The index arm is clamped in any desired position by means of a nut and a central
binding screw passing through the hub. Both index arms have segmental apertures,
each graduated along both edges to form verniers for the graduated arc whose
graduations may be on two different systems indicating linear measurement such,
for instance, as inches and centimetres. The index arm gears by teeth about its
centre with a toothed segment about the pivotal centre of an arm pivoted to the said
plate, and adapted to carry a divider or an inside or outside caliper leg. Any one of
the legs may
be fastened to the said arm (according to the purpose for which the
instrument is required) by means of a bolt, the leg taking a bearing against the inside
of the arm and a lug on the arm fitting into a corresponding notch in the leg so as to
maintain a rigid connection, the outer end of the arm being bevelled and fitting into
a corresponding undercut formed in the leg. The other leg of the dividers, inside or
outside calipers is bolted directly to the dial plate and is held in place by a lug fitting
in a notch in the edge of said plate, a bevel on the edge of the plate also fitting in
an undercut on the arm so that a rigid connection is maintained. Each divider leg
has a V-shaped groove along its inner edge in which a similarly shaped divider point
is clamped by a binding screw passing through a longitudinal slot in the leg to
permit of adjusting the point when worn out or sharpened. The one inside caliper
leg has an outwardly directed point and the other leg has a friction-roller, the outside
caliper legs being similar, but inwardly directed. On the plate is formed a thumb
rest for conveniently adjusting the index when necessary.

page_text: The instrument is used as follows:-Supposing the divider legs to be applied, the
instrument may be used for all purposes for which dividers are commonly employed.
The divider points are opened or closed by moving the index over the dial plate.
When opened or closed to the desired distance, the exact distance in inches and in
centimetres or other units between the outer ends of the points is indicated by the
verniers and scales on the front of the dial plate. The mode of use is the same when
the inside caliper legs are substituted for the divider legs, the motion of the index over
the dial plate bringing the point of the one leg and the wheel on the other against
the parts to be calipered. The distance between the point and the outer part of the
wheel is then indicated either in inches or centimetres by the verniers and scales on
the rear of the dial plate. When outside caliper legs are substituted, the
operation is the same, but the distance between the point on the one leg and the
wheel on the other is indicated by the verniers and graduations on the front of
the plate.
Thus it will be seen that, by a few slight changes, I am enabled to change the
instrument from a divider into an inside or outside caliper, and vice-versa the distance
measured being always indicated.

page_text: An Improved Measuring and Drawing Instrument..
I, THOMAS GREEN of 651 Christy Strect, in the City of Davenport, County of
Scott, and State of Iowa, 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:-
This invention relates to an improved measuring and drawing instrument specially
adapted for use by mechanics, for the various purposes for which inside and outside
calipers, dividers, etc. are ordinarily employed.
Reference is to be had to the accompanying drawings forming a part of this
specification, in which figure 1 is a front face view of the instrument (partly in
section) adapted for use as dividers. Figure 2 is a section of the same, on the
line of figure 1. Figure 3 is a rear face view of the same. Figure 4 is a cross
section of one of the legs, on the line y-y of figure 1. Figures 5 and 6 are
respectively face views of pairs of inside and outside caliper legs to be used in
connection with the instrument. Similar letters of reference indicate corresponding
parts in all the figures.
The improved measuring and drawing instrument A comprises a plate B having a
graduated are and a central hub C at each side on which is pivoted an index D
consisting of a pair of quadrant shaped arms working over the two faces of the
graduated arc B and united at their outer ends so as to embrace the periphery B¹
and move together over the graduated arc, as is plainly shown in figures 1 and 2.
The index D may be clamped in any desired position by a bolt E, passing through
the hub C, a washer F being interposed between its head E' and one of the arms of
the index D, a nut E' on the bolt pressing against the other arm, whereby the index
is fixed or permitted to turn freely.
The arm of the index D has segment shaped apertures D' D' immediately over the
face of the arc each aperture being graduated along both of its curved edges a¹ b¹ c¹ d¹
to form verniers for the graduated arc. The verniers a¹ 61 correspond respectively with
graduations ab on the arc B' as shown in figure 1, whilst the verniers c and c¹
correspond with the graduations d and d on the rear face of the arc.
graduations a and b may be on two different systems, indicating linear measurement,
such for instance as inches and centimetres and sub-divisions thereof as likewise the
graduations c and d on the rear face of the arc B¹.
The
The one arm of the index D is toothed about the centre, and said teeth D³ gear with
a toothed segment G, pivoted on a bolt H, secured in the plate B, the said segment G
being in one with an arm G adapted to carry a divider leg I or an inside or outside
caliper leg J or K illustrated in figures 5 and 6. Any one of the legs I. J or K may
be fastened to the arm G' by means of a bolt L passing through the leg and screwing
into the arm G'. The latter has a lug G which fits into a corresponding notch I³, J
or K in the leg I, J or K, whilst the outer end G³ of the arm is bevelled and fits
into a corresponding undercut 13, J³, or K³, formed in the leg so that a firm connection
is maintained between the parts.

page_text: The other leg I', J¹, or K' of the dividers, inside or outside calipers is secured
directly to the plate B by a bolt N, passing through it and screwing into the plate B,
and is held in place by a lug I, J or Kformed on the arm fitting into a notch B
in the edge of the plate B, a bevelled part B³ of the periphery of the plate B fitting
a corresponding undercut 15, J or K, on the leg 1, J, or K.
The arms I, I, and J, Jare also additionally provided with projecting sides I*, I'
and J, J' which respectively fit against the inside of the arm G and against the edge
of the plate B.
Each divider leg I and I' has a V-shaped groove I along its inner face, in which
a similarly shaped divider point O or O is clamped by a binding screw P or P1
passing through a longitudinal slot 1' in the leg I or I', to permit of adjusting the
point or O, when worn out or sharpened.
The one inside caliper leg J has an outwardly-directed point J and at the
extremity of the other leg J₁ is mounted a friction roller J. Similarly the outside
caliper legs K and K¹ have an inwardly-directed point K and a friction roller K'.
On the plato B is formed a thumb rest for use in adjusting the index D.
When the divider legs I are applied the instrument may be used for all purposes
for which dividers are commonly employed. In order to open or close the divider
points O and O¹, the plate B is held and the index D moved along the graduated arc,
whereby the points and O¹ are caused to move toward or from each other to the
desired distance, the exact distance in inches between the outer ends of the points O
and O being indicated by the vernier a', whilst the vernier 6 indicates the same
distance in centimètres or other unit of measurement adopted.
When the inside caliper legs J' are substituted for the divider legs the instrument
forms an inside caliper and is used in the way above described for inside-calipering,
that is to say, the index D is moved along the arc until the point J and the wheel J
are brought against the parts to be calipered. The distance between the point JB
and the outer part of the wheel J' is then indicated either in inches or centimetres by
the verniers ef and d¹ on the rear face of the arc B¹.
When the outside caliper legs K and K are substituted, the operation is the samo,
the distance between the point K and the wheel K' when they touch the part to
be calipered on both sides, being indicated by the verniers a¹ and b¹ on the front of
the arc B¹.
Thus the instrument may be readily converted from a divider into an inside or
outside caliper and vice versa, whatever distance is measured being always indicated
on the graduations a, b, c, or d.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is.
1. In a measuring and drawing instrument, the combination, with a plate having
a graduated arc, and a fixed leg, of an index pivoted to the plate to work over the
said graduated arc and geared by teeth about its centre with a toothed segment on an
arm pivoted on the plate and adapted to carry a divider or caliper leg, substantially as
shown and described.
2. In a measuring and drawing instrument, the combination, with a plate having
a graduated arc, of an index pivoted to the said plate to work over the said graduated
are and geared with a toothed segment on an arm pivoted on the said plate, and
divider legs respectively fixed on the said plate and on the segment arm, substantially
as shown and described.
3. In a measuring and drawing instrument, the combination, with a plate having
a graduated are, of an index pivoted on the said plate to work over the graduated arc,
gear teeth on the index, a toothed segment in gear with the index and pivoted on the
plate, and an arm carried by the segment, and inside caliper legs respectively attached
to the said plate and to the said segment arm substantially as shown and described.
4. In a measuring and drawing instrument, the combination, with a plate having
a graduated arc, of an index pivoted on the said plate to work over the graduated arc,

page_text: gear teeth on the index, a toothed segment in gear with the index and pivoted on
the plate, an arin carried by the segment, and outside caliper legs respectively
attached to the said plate and to the segment arm, substantially as shown and
described.
5. In a measuring and drawing instrument, the combination, with a plate provided
with a lug and bevelled part, of a leg secured to the said plate by a bolt and
provided with a recess in which fits said lug, and also provided with an undercut fitting
on to the said bevel, substantially as shown and described.
6. In a measuring and drawing instrument, the combination, with a plate provided
with a notch and a bevelled part, of a leg secured to the said plate by a bolt and
provided with a lug fitting into the said notch, and also provided with an undercut
fitting onto the said bevel, a segment arm pivoted on the said plate, and a leg
fastened to the segment arm by a bolt and provided with a notch fitting onto a lug
on the seginent'arm, and with an undercut fitting on the bevel end of the segment arm,
substantially as shown and described.