Improvements in Gun Sights.
Year: 1889

page_text: COMPLETE SPECIFICATION.
Improvements in Gun Sights.
I, JOHN SERGEANT BLANKMAN, residing at 1209 F Street, Washington, District of
Columbia, in the United States of America, gentleman, do hereby declare the nature
of my invention for IMPROVEMENTS IN GUN SIGHTS, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement :-
The present invention embraces improvements upon an invention in Gun Sights
patented to me January 8th, A.D. 1889, No. 340, and it consists in the matters herein-
after described and pointed out.
In the accompanying drawing,
Fig. 1 is a side elevation partly in section of an extensible or compound gun sight
tube attached to a gun barrel.
Fig. 2 is an enlarged transverse section on the line x-x of figure 1.
Fig. 3 is a cross section of one form of sight tube and Figs. 4, 5, 6, 7 and 8 are
cross sections of different forms of one part of the compound sight tube, figure 8 being
on an enlarged scale and showing a modification of sight pins.
Fig. 9 is a cross section enlarged indicating cross wires or hairs, and also a special
arrangement of the inner part of the compound sight tube.
Fig. 10 is a longitudinal section of one form of the main or larger part of the
compound tube, the dotted lines indicating diagramatically the use of sight notches for
various ranges.
Fig. 11 is a top plan view of the same, and
Figs. 12 and 13 are respectively longitudinal and transverse sections of a modifi-
cation of a part of the tube, shown in figures 10 and 11.
Fig. 14 is a transverse section of the tube and base piece in the region of the key
and stop.
Fig. 15 is a side elevation partly in section, and
Fig. 16 is a sectional plan of my improvement applied to a gun.
The sight tube is composed of the part 1 which may be secured to a gun barrel in
any usual or preferred way, but which in the present instance is shown as secured in a
base 5 having a dovetail key 3 of usual form fitting transversely in a similarly shaped
slot in the barrel.
This dovetail piece, however, is preferably provided with a stop 4 shaped to conform
to the surface of the barrel and designed to locate and hold the key 3 in its proper
lateral position.
This tube 1 may be secured in the base plate by a lengthwise dovetail con-
nection such as indicated at 9 in figure 2, or a construction similar to that indicated
in figure 3 may be substituted, such figure showing means for connecting a tube 2
direct to a base provided with dovetail lock or key of customary form. The tube
may be connected to the base plate or to the barrel by any convenient arrangement of
keys or flanges, substantially such as indicated.
2 is a tube made of a form and size to fit within the tube and be movable therein
with sufficient friction to retain any desired position longitudinally.
Each part of the compound tube is preferably provided at the top with an opening
or series of openings to admit light to its interior. In tube 1 said openings are
indicated at 6 in the several figures and in tube 2 at 7.
The tube 2 as stated slides within the tube 1 and is adjusted lengthwise to make
the compound tube longer or shorter, as desired, it being understood that the longer
the extensible tube is made the smaller will be the field of vision. The invention is
not limited to the use of two tubes as a larger number fitting each other telescopically
may be employed if desired, or the tubes 1 and 2 may be separated and other

page_text: used alone. The tube 2 is represented in figures 1 and 2 and has its slotted side
uppermost as is the case with tube 1, but if it is desired to exclude a part of the
light which ordinarily enters these slots tube 2 can be partially turned and inserted
as indicated in figure 9. And it is obvious that tlie inner tube might be still
further turned so that its flanged side 11 (Fig. 9) would close the openings 6 in
tube 1, which might be advisable under different circumstances either to exclude
light or moisture. The tube 2 may have various forms in cross section and in
some modifications, such for example, as illustrated in figures 1 and 2, 5, 7 and 8
may be stamped out of sheet metal as also may be tube 1.
According to the arrangement illustrated in figure 9, as will be seen, the inner tube
does not entirely fill the outer one, but leaves tube like spaces between them at 13, 13.
These spaces are adapted to aid the marksman in approximating a central line of
sight through the inner tube, or in case of high wind the sight obtained through
these outer tubular spaces may be used for directing the firing, with allowance for
wind deviation.
In figures 10 to 13 is indicated an additional sight device applied to tube 1,
which consists in a notch 12, in a cross bar 15, which latter constitutes a part of
the upper side of the tube and which device is adapted for use in long ranges as
diagramatically denoted by means of the dotted lines. Thus for an ordinary range
the line of sight will pass through the tube near an axial line, but for a long
-range requiring an elevation of the muzzle of the gun the line of sight after
entering the forward end of the tube will pass out through its open top and the
construction is such that the correct sight will be indicated by the first ray that
passes from the mark through the notch to the eye. And these notches may be
ärranged to correspond with ranges of various extent so as to indicate their length,
i.e. the distance of the mark. These notches can be used in the double or compound
tube above described and the pins 8 (Fig. 8) will be useful for short ranges and
the notches in combination with a front or muzzle sight for longer ones.
The sight pins are doubled or branched as shown in figures 1 and 2 and in a
modified form in figure 8. The advantage of this form of pin is that when the mark
is viewed between its two adjacent parts any deviation from a straight line passing
from the mark or the muzzle sight to the eye between said parts begins to be visible
at the commencement of such variation while in case of solid pins arranged exactly
in the line of vision a material variation must occur before it is perceived. The
function of the notches 12 are, however, independent of sight pins:
Instead of several cross bars indicated in figures 10 and 11 an adjustable one
may be employed as illustrated in figures 12 and 13, and one or more of the cross bars
may be notched on both sides.
My sight tube is distinguished from a mere sight protector such as a ring of short
tube which is usually located near the gun muzzle, in respect to its location, forin and
functions. It is placed in rear of the front sight and is made in the form of a tube of
söme längth its general functions being to confine or limit the field of vision and it
ordinarily consists of two members, one of which slides within the other in such
manner as to leave several sight tubes or passages between them and arranged to
provide when desired, for an extension of the compound tube, and also to provide for
obscuring more or less the light openings by various arrangeinent of the tubes in
transverse direction.
The flange provided on the key has special relation to my tube sight and prevents
the latter from being moved out of the proper line laterally by a slight pivotal or
rotary movement of the key in case it or its seat has become worn, or in case the
original fit was not tight. While such a movement in an ordinary sight pin would
be of no practical consequence it is important to obviate it in the case of a long
Bight tube, and this device is intended to prevent any tendency however slight and
under whatever conditions in the sight tube and its key towards turning laterally in
the key seat.
short
My invention is further to be distinguished from sights which embrace
tube fitted to a tubular seat; but not adapted to be adjusted lengthwise thereiti to

page_text: vary the length of the sight tube nor adapted to be adjusted to form several sight
passages parallel to the axis of the tube.
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 combination with a gun, and its ordinary muzzle sight, a rear sight tube
having unobstructed light openings in its side, substantially as described.
2. In combination with a gun a sight tube having an opening in its upper
side, the edge of the material at the end of said opening and bounding the same
being provided with a notch located in a plane passing through the line of sight,
substantially as described.
3. In combination with a gun, a muzzle sight, and a compound tube having two
members one normally sliding within the other and adapted to vary the length of
the compound tube, substantially as described.
4. In combination with a gun, a sight tube consisting of two members normally
sliding one within the other and forming several longitudinal sight passages parallel
to the axis of the tube, substantially as described.
5. In combination with a gun a compound tube having two members one sliding
within the other and adjustably held therein each provided with a light opening in
its upper side, substantially as described.
6. A compound sight tube having two members one sliding within the other, each
provided with a light opening in one of its sides, the inner tube being adapted to
enter the outer with either of its sides adjacent to the open side of the outer tube,
substantially as described.
7. In combination with a gun and with a muzzle sight, a rear sight tube provided
with a double or notched sight pin, substantially as described.
8. In a sighting device the combination of a rear sight tube with a muzzle sight
and with a key for securing the sight tube to a gun barrel provided with a stop
conforming to the surface of a gun barrel, substantially as described.
9. In a sighting device a sight tube provided with a base having a key integral
therewith and adapted to fit a suitable slot in the gun barrel, said base having also
flanges to engage a sight tube, substantially as described.
Dated this 3rd day of December 1889.
ABEL & IMRAY,
Agents for the Applicant.