A NEW OR IMPROVED INSTRUMENT OR APPARATUS FOR GAUGING OR MEASURING THE INTERNAL DIAMETERS OR BORES OF GUN BARRELS, TURES, AND TUBULAR ARTICLES
Year: 1875

page_text: LETTERS PATENT to Samuel Blakemore Allport, of Birmingham, in
the County of Warwick, Gun Manufacturer, for the Invention of
"A NEW OR IMPROVED INSTRUMENT OR APPARATUS FOR GAUGING OR
MEASURING THE INTERNAL DIAMETERS OR BORES OF GUN BARRELS, TURES,
AND TUBULAR ARTICLES.”
Sealed the 23rd December 1875, and dated the 15th July 1875.
PROVISIONAL SPECIFICATION left by the said Samuel Blakemore
Allport at the Office of the Commissioners of Patents, with his
Petition, on the 15th July 1875.
I, SAMUEL BLAKEMORE ALLPORT, of Birmingham, in the County of
Warwick, Gun Manufacturer, do hereby declare the nature of the said
Invention for "A NEW OR IMPROVED INSTRUMENT OR APPARatus for GauginG
OR MEASURING THE INTERNAL DIAMETERS OR BORES OF GUN BARRELS, TUBES, AND
TUBULAR ARTICLES,” to be as follows :-
My Invention consists of a new or improved instrument or apparatus
for gauging or measuring the internal diameters or bores of gun barrels,

page_text: tubes, and tubular articles, the parts of the said instrument or apparatus
being constructed and combined substantially as herein-after described.
The said instrument or apparatus is specially fitted for gauging or
measuring the bores of gun barrels during the process of manufacture or
after they have been manufactured, but the said instrument or apparatus
may also be applied to the gauging or measuring of the internal
diameters of tubes and tubular articles generally.
'
By the use of the said instrument or apparatus the internal diameters
or bores of gun barrels, tubes, and tubular articles are measured very
minutely and with great exactness.
The said instrument or apparatus consists of a tube of any required
length provided at one end with a convex screw upon which a tubular
collar having a corresponding concave screw works. The said tubular
collar is provided with a milled head for turning it. This collar is
graduated with divisions on its periphery at its inner end. On the 1
opposite end of the tubular body is mounted a series of three or other
number of spring arms. The free ends of these spring arms are enlarged
and are curved externally, but are flat or concave internally. The said
free ends are disposed radially around and bear upon an adjustable cone.
.This cone is connected by means of a rod passing through the tubular
body of the instrument with the graduated screw collar herein-before
described. By turning this screw collar in one or other direction by
means of its milled head the cone connected with it is made to advance
or retire between the free ends of the spring arms, so as to open out or
expand the said arms, or permit the said arms to close or collapse upon
the cone.
It is by the expansion or contraction of the spring arms by or upon
the cone described that the gauging or measuring is effected; the pitch
of the screw of the graduated screw collar connected with the cone
bearing such a relation to the angle of the said cone that the said
expansion or contraction of the spring arms is indicated in thousandths
of an inch by the divisions on the periphery of the screw collar.
By means of graduations on the tubular body in conjunction with
those on the screw collar, the bore of the barrel or tubular article may
be gauged or measured with great exactness. The tubular body is
graduated into inches in addition to the small graduations referred to.

page_text: In using the instrument it is introduced into the gun barrel, tube, or
tubular article, and the screw collar at the head of the instrument
turned until the circumferential parts of the spring arms bear against
the inside of the barrel or article. The gauge is indicated by the
position of the screw collar with respect to the graduations on the
cylindrical body; and the distance of the part gauged from the mouth
of the barrel is indicated by the inch graduations on the said body.
.
For the purpose of preserving the instrument during use concentric
with the axis of the barrel or tube, a moveable or adjustable conical
collar may be fixed near the upper part of the instrument, so that when
the instrument is used the said conical collar drops into the mouth of
the barrel and prevents lateral motion in the instrument. By adjusting
the position of the conical collar on the tubular body of the instrument,
the said collar may be used with barrels having bores of different
diameters.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Samuel Blakemore Allport in the Great Seal
Patent Office on the 4th January 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, SAMUEL
BLAKEMORE ALLPORT, of Birmingham, in the County of Warwick,
Gun Manufacturer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifteenth day of July, in the year
of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Samuel Blakemore Allport,
Her special license that I, the said Samuel Blakemore Allport, my
executors, administrators, and assigns, or such others as I, the said
Samuel Blakemore Allport, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and
at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United King-
dom of Great Britain and Ireland, the Channel Islands, and Isle of
Man, an Invention for "A NEW OR IMPROVED INSTRUMENT OR APPARATUȘ FOR

page_text: GAUGING OR MEASURING THE INTERNAL DIAMETERS OR BORES OF GUN BARRELS,
TUBES, AND TUBULAR ARTICLES," upon the condition (amongst others) that
I, the said Samuel Blakemore Allport, my executors or administrators,
by an instrument in writing under my, or their, or one of their hands
and seals, should particularly describe and ascertain the nature of 5
the said Invention, and in what manner the same was to be per-
formed, and cause the same to be filed in the Great Scal Patent
Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said Samuel Blakemore Allport, do 1
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascer-
tained in and by the following statement thereof, that is to say :—
My Invention consists of a new or improved instrument or apparatus
for gauging or measuring the internal diameters or bores of gún barrels, 1
tubes, and other tubular articles, the parts of the said instrument or
apparatus being constructed and combined substantially as herein-after
described.
. The said instrument or apparatus is specially fitted for gauging or
measuring the bores of gun barrels during the process of manufacture or 2
after they have been manufactured, but the said instrument or apparatus
may also be applied to the gauging or measuring of the internal
diameters of tubes and tubular articles generally.
By the use of the said instrument or apparatus the internal
diameters or bores of gun barrels, tubes, and tubular articles aro
measured very minutely and with great exactness.
The said instrument or apparatus consists of a tube of any required
length provided at one end with a convex screw upon which a tubular
collar having a corresponding concave screw works. The said tubular
collar is provided with a milled head for turning it. The collar is 3
graduated with divisions on its periphery at its inner and. On tho
opposite end of the tubular body is mounted a series of three or other
number of spring arms. The free ends of theso spring arms are enlarged
and are curved externally, but are flat or concave internally. The said
free ends are disposed radially around and bear upon an adjustable cone. 3
This cone is connected by means of a rod passing through the tubular
body of the instrument with the graduated scrow collar herein-before

page_text: described. By turning the screw collar in one or other direction by
means of its milled head, the cone connected with it is made to advance
or retire between the free ends of the spring arms, so as to open out or
expand the said arms or permit the said arms to close or collapse upon
the cone.
It is by the expansion or contraction of the spring arms by or upon
the cone described that the gauging or measuring is effected; the pitch
of the screw of the graduated screw collar connected with the cone
bearing such a relation to the angle of the said cone that the said
expansion or contraction of the spring arms is indicated in thousandths
of an inch by the divisions on the periphery of the screw collar.
By means of small graduations on the tubular body in conjunction
with those on the screw collar, the bore of the barrel or tubular article
may be gauged or measured with great exactness. The tubular body is
graduated into inches in addition to the small graduations referred to.'
In using the instrument it is introduced into the gun barrel, tube, or
tubular article, and the screw collar at the head of the instrument
turned until the circumferential parts of the spring arms bear against
the inside of the barrel or article. The gauge is indicated by the
position of the screw collar with respect to the small graduations on the
cylindrical body, and the distance of the part gauged from the mouth of
the barrel is indicated by the inch graduations on the said body.
For the purpose of preserving the instrument during use concentric
with the axis of the barrel or tube, a moveable or sliding conical collar
may be placed on the instrument, and when the instrument is used the
said conical collar may be adjusted so as to drop into and fit the mouth
of the barrel, and thereby prevent lateral motion in the instrument.
The conical shape of the collar adapts it to barrels or tubes of different
diameters.
Having explained the nature of my Invention, I will proceed to
describe with reference to the accompanying Drawing the manner in
which the same is to be performed.
Figure 1 represents in elevation, and Figure 2 in longitudinal section
a gauging or measuring instrument constructed according to my
Invention drawn half the full size, the said instrument being graduated
to gauge the bores of gun barrels,

page_text: The same letters indicate the same parts in the several Figures of the
Drawing.
a is the graduated tube of the gauge having at its rear end the convex
screw 6 (best seen in Figure 3), upon which the tubular collar c (best 1
seen in Figure 4) having a corresponding concave screw works. The
inner end of the tubular collar c is graduated at d, and the outer end is
furnished with a milled head c³ for turning it. The rear end of the
tube a, upon which the tubular screw collar c works, is graduated at aº.
Attached to the front end of the tube a of the gauge are spring 2
arms e, e, connected by the part e³ to the said tube a. The free ends
of the spring arms e, e, are enlarged and are curved externally, and are
by preference flat internally, as seen in the end elevation, Figure 7. In
the axis of the graduated tube a is a rod f, the fore end of the said rod
having upon it a cone g. The free ends of the spring arms e, e, are 2
disposed radially round and bear upon the said cone g (see Figure 2).
The rear end of the rod fcarrying the cone at its front end passes
through the screw 6 of the tube a, and is fixed by means of the plug h
to the head of the graduated screw collar c. The manner in which the
square end of the rod fis fixed in the slightly conical plug h, which 3
plug is driven into the head of the collar c, is best seen in Figure 2.
By turning the screw collar c by the milled head of in one or other
direction the cone g connected to the said collar through the rodƒ is
made to advance or retire between the free ends of the spring arms e, e,
so as to open out or expand the said arms or permit them to close or 8
collapse upon the cone 9. By means of a washer i fixed by a screw

page_text: nut in front of the cone g and acting as a stop the said cone g is
prevented from being completely drawn through the free ends of the
spring arms e, e. On the outside of the tube a of the gauging instru-
ment is a moveable or adjustable conical collar k. By adjusting this
collar k at the proper place on the tube a the said collar drops into the
mouth of the gun barrel when the instrument has been introduced to
the required distance in the barrel, and preventing lateral motion in
the instrument preserves the said instrument concentric with the
barrel.
0
The gauging or measuring is effected by the expansion or contraction
of the spring arms e, e, by or upon the adjustable cone g, the pitch of
the screw collar o on the rod f of the said cone bearing such a relation
to the angle of the said cone g that the said expansion or contraction of
the spring arms e, e, is indicated in thousandths of an inch by the
graduations at d on the periphery of the screw collar e in combination
with the graduations at a' on the tube a. Each of the graduations at
aª on the tube a is equal to '020 of an inch, and the screw collar o by
being made to perform one rotation advances through that distance,
that is, through 020 of an inch. When the extreme sharp edge of the
screw collar c exactly coincides with the line over the graduation 800
in Figure 3 it indicates that the spring arms e, e, will, when the said
collar c is in that position, exactly fit the interior of a gun barrel having
a diameter of 800 of an inch. When the extreme sharp edge of the
screw collar c coincides with the line over the graduation "700 in
Figure 3 the spring arms e, e, are expanded to a diameter of 700 of an
inch, and so on with the other graduations.
Sizes intermediate between those indicated by the lines in Figure 3
are measured by the divisions at d around the screw collar c, the said
collar being divided into 20 equal parts.
Let it be supposed that the instrument is introduced into a tube or
gun barrel, and the screw collar c is turned until the spring arms e, e,
are expanded and made to fit the interior or bore of the said tube or
barrel.
By an examination of the screw collar c the internal diameter or
bore of the tube or barrel will be indicated. If the graduated edge d of
the collar c be situated somewhere between the graduations 800 and
*780, and the division 5 on the collar c is opposite the line p on the

page_text: bore or internal diameter of the gun barrel or article by means of
graduations on the tube and screw collar, the several parts being
constructed, arranged, and used substantially as described and illus-
trated.
In witness whereof, I, the said Samuel Blakemore Allport, have
hereunto set my hand and seal, this First day of January, in
the year of our Lord One thousand eight hundred and seventy-
Bix.
Witness,
GEORGE SHAW.
SAMUEL BLAKEMORE ALLPORT. (L.S.)