Improvements in Sighting-apparatus for Guns.
Year: 1893

page_text: Date of Application, 30th May, 1893
Complete Specification Left. 28th Feb., 1894-Accepted, 31st Mar., 1894
PROVISIONAL SPECIFICATION.
Improvements in Sighting-apparatus for Guns.
I, HUBERT HENRY GRENFELL, of 18 Ashburn Place, in the County of
Middlesex, Captain, Royal Navy, do hereby declare the nature of this invention
to be as follows:-
:-
This invention relates to sighting apparatus characterized by the following
features, viz, a telescope, mounted on the end of a sight-bar which is of circular
curvature and is formed and arranged to give automatically the correction for
drift, at any elevation. Also the combination of the said telescope and curved
sight-bar with means for rotary adjustment of the telescope about a pivot on the
bar to correct the aim by allowance for deflection by wind or other lateral deviation.
Also the combination with the said circularly-curved sight-bar and telescope, of
an indicating-apparatus for shewing the range distinctly..
Also the combination with the said circularly curved sight-bar and telescope
of an apparatus to compensate for lateral inclination, in the case of a field gun,
for example.
The said sight-bar is made of suitable length in the form of the arc of a circle,
and is provided with rack-teeth to gear with a pinion for effecting its vertical
adjustment through the guide or socket. But according to my present invention
the said sight-bar not only curved in a plane extending fore and aft of the gun
but is also twisted or is slightly curved transversely to this plane, in such a manner
that the telescope when adjusted vertically for any range will automatically, and by
the action of the said twist lateral curvature or inclination of the bar, as it moves
through the guide, make the necessary correction for the drift.
The said guide or socket is carried by a frame which can be attached to any
suitable part of the gun the said socket having its upper and lower ends fitted to
turn freely in bearings in the said frame. Worm teeth are formed in a convenient
position on the exterior of the socket, and a screw with a milled head is geared
with these teeth; by means of this milled head the screw can be manipulated to
turn the said socket about its vertical axis in the said bearings. The sight-bar
and telescope are turned with the socket and thereby the said telescope can be very
conveniently adjusted to rectify any error due to the force of wind moving in a
lateral direction.
The said frame is in some instances made in two parts, one part carrying the
said guide or socket, being pivoted at its upper end to the other part, which is
attached to the gun. An adjusting screw and a mercury or spirit level are
combined with the said frame whereby any unevenness of the wheels or other
supports of the gun can be allowed for.
Upon the sight-bar, in certain cases, I pivot a lever which carries a detent
such a manner as to retain it securely in place, provide other means to serve
adapted to be brought into or out of engagement with the aforesaid telescope in
or to permit it to be readily
removed when desired. Or, as alternatives,
the same purposes.
Moreover, according to my present invention, I combine with the circularly-
curved sight-bar and with the means for automatic correction for drift and the
rotary adjustment for wind, an indicating apparatus which is geared with the afore-
said rack-teeth through the medium of a spirally-formed pinion and which shows

page_text: the range or elevation in very plain figures on a disc or dial, substantially as
described in the Specification of my former Patent No. 934 of 1892.
Dated this 30th day of May 1893.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Sighting-apparatus for Guns.
I, HUBERT HENRY GRENFELL, of 18 Ashburn Place, in the County of
Middlesex, Captain, Royal Navy, 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 sighting-apparatus characterized by the following
features, viz. :-The combination with a curved sight-bar on which is fixed a
telescope or equivalent device having fore and hind sights, as described, for
example, in the Specification of prior Letters Patent No. 13549 of A.D. 1888
granted to me, of range-indicating apparatus in operative connection with the
sight-bar, such connection having a variable velocity-ratio. Also, a sight-bar fitted
with sighting devices as aforesaid and formed and arranged to give, automatically,
the correction for drift, at any elevation. Also, the combination with the said
sighting-device and the curved sight-bar, of means for effecting the rotary
adjustment of the sighting device about a pivot, to correct the aim by allowance
for deflection by wind or other cause which produces lateral deviation additional
to the amount of drift corrected automatically as aforesaid.
In order that my said invention may be clearly understood I will now proceed
to describe the same with reference to the accompanying drawings, wherein
Figure 1 is a side elevation of an improved sighting-apparatus constructed
according to this invention,
Figure 2 is a view similar to Figure 1, partly in section on the line X X of
Figure 3,
Figure 3 is a rear elevation, and
Figure 4 is a plan of the sighting-apparatus shewn in Figure 1.
Figure 5 is a sectional plan, and
Figure 6 is a section, of the sight-bar, on the lines Y Y and Z Z, respectively,
of Figure 2.
Figures 7 and 8 are sections on the lines X' X and Y Y', of Figures
respectively.
and 4,
Figure 9 is a view of a part of Figure 2, on the line Z' Z' of the last-named
figure.
Figure 10 is an underside view of the device shewn in Figure 9.
Figures 11, 12, 13 and 14 are views of the gearing employed to connect
the rotary indicating-discs of the range-indicating apparatus hereinafter referred
to, and
Figures 15 to 24 are views, hereinafter particularly described, of indicating-
devices provided with internal mechanism different from the mechanism in the
indicator which forms part of Figures 1, 2 and 3.
Like reference-letters indicate corresponding parts throughout the drawings.
A is a bracket which can be attached to any suitable part of the gun. A° is a
renovable frame, held in place in a suitable groove in the bracket A, by means
hereinafter described. B is a guide socket having its upper and lower ends fitted
to turn easily in bearings in the parts A' A' of the frame A°. B° is a lug formed t
upon the guide socket B. C is a screw-threaded spindle which turns in a tapped
hole in the part A' of the frame A° and is provided with a spherical end C¹ which

page_text: is received in a chamber formed in part by a cavity in the lug B° and in part by a
conically-bored nut B' screwed into the said cavity (see Figure 8). C³ is a disc
fixed to the spindle C. The said disc is provided with a milled rim whereby it
and the spindle C can be conveniently rotated to turn the guide socket B. A
portion C of the periphery of the disc is suitably graduated to be employed with
reference to the index or arrow-head A³ on an adjoining circalar portion A* of the
frame A° as a guide to the adjustment of the guide socket B for a purpose herein-
after specified. A is a bolt which slides in a recess in the frame Aº and is kept
in engagement with a notch in the bracket A by a spring A* so that the
frame A is thereby locked securely in its place in the bracket. A' is a thumb
piece secured to the bolt A'; it projects to the exterior of the frame A°, and can
be moved to draw the bolt A' back into the recess in the frame when it is
desired to disengage the frame from the bracket.
D is a circularly-curved twisted sight-bar, adapted to slide in the direction of
its length through a similarly curved and twisted channel in the guide socket B.
The twist of the sight-bar is like that of a screw with a pitch very great in
proportion to its diameter. This twist effects the aforesaid automatic correction
for drift, in the manner hereinafter explained.
It is an important feature of my invention that the turning of the guide socket
effects the turning of the sight bar to adjust, laterally, the line of sight to make
correction additional to the automatic correction for drift consequently there is no
need for the employment, as heretofore, of adjusting devices at the head of the bar.
D' is a toothed rack formed upon one side of the sight-bar; D' is a channel formed
at the opposite side thereof, to receive the ends of a spring B' (Fig. 3) which is
secured in the guide socket B and serves to keep the sight-bar steady therein.
E is a telescope held in a suitable groove in the part D³ of the head of the sight-
bar; EE are auxiliary sights fixed upon the exterior of the telescope as shown.
E is the milled head of the focussing-screw of the telescope. D* is a screw by
which the telescope is retained in place on the sight-bar.
The said sight-bar is made of suitable length, in the form of an arc of a circle;
the rack-teeth D' gear with a pinion for effecting its vertical adjustment through
the guide-socket, as hereinafter set forth.
I connect the range-indicating device with the sight-bar by a peculiar arrange-
ment of gearing producing a variable velocity-ratio, whereby, notwithstanding the
varying lengths of movement of the bar which correspond with equal increments
of range, the indicator discs are operated in such a manner as to give equally
clear correct indications for all ranges of the gun This part of my invention
is substantially similar to the invention set forth in the Specification of former
Letters Patent No. 934 of A.D. 1892 granted to me but in the present instance
the indicating-apparatus is shown and described in its application to a curved
Sight-bar, whereas the said prior Specification describes its application to a straight
sight-bar. B' is a chambered extension formed upon the socket B. F is a spindle
arranged to turn in bearings in the said extension and provided with a milled
wheel or disc Fat its outer end, F is an ordinary toothed pinion secured to the
inner end of the spindle F and geared with the rack D'. The spindle F has also
a spirally-formed taper wheel or rack F3 fixed thereon, and provided with a series
of teeth on its peripheral surface as shown. G is the range-indicator. H and I
are the rotary indicating-discs thereof, geared together by any suitable means,
such, for instance, as those shewn in Figures 11, and 12, or 13 and 14, and herein-
after particularly described. The disc H indicates "thousands" and the disc I
6: hundreds;' The indications may signify distance either in yards or in other
units, as desired. G is the outer face or cover of the indicator, G³ is an aperture
in the face or cover through which the indications on the discs H and I can be
seen. J is a pinion on a square spindle J' which spindle has its inner end supported
in a bearing K in the aforesaid extension B. The said pinion J can turn with,
but not independently of the spindle J'; it gears with the spiral wheel F. The
said spiral wheel is of varying diameter through the whole length of its periphery;
"

page_text: it is therefore obvious that special provision must be made for keeping the said
pinion J in gear with it. With this object I arrange the said pinion within a
yoke J (see Figures 9 and 10) which is fitted to slide upon the spindle J1 and has
cheeks which embrace the edge of the spiral wheel; a part J of the yoke is
arranged to enter the guide groove B₁ in the extension B³, so that as the spiral
wheel F presents different parts of its periphery to the pinion J, the latter is
caused by the yoke to slide along the square spindle thereby maintaining its proper
connection with the said spiral wheel.
One form of gearing for connecting the rotary indicating-discs H and I is
shown in Figures 11 and 12, which represent it in elevation and vertical section
repectively. In this mechanism the "thousands" disc H is secured to a collar H¹
which turns in a bearing in the frame of the indicator, and carries a pinion H'.
The "hundreds" disc I is secured upon one end of the aforesaid spindle J',
which passes through the collar H'. To the spindle Ja finger L, and also a
locking disc M with a gap M' in its periphery, are secured. N is a stud screwed
into the frame of the indicator as shown. O is a pinion rotatable upon the said
stud and geared with the pinion H². P is a locking piece with segmental gaps Pl
Qis a star
in its periphery; it is adapted to engage with the locking disc M.
wheel provided with radial slots Q₁ to receive the end of the finger L. The
pinion O, locking-piece P, and star wheel Q rotate together.
The operation of the said improved sighting and indicating device is as
follows, viz.:-
The spindle F is operated by means of its dise or head F¹ and the pinion F* is
thereby caused to act upon the rack D' to slide the curved sight-bar up or down
through the guide-socket B. The sight-bar, in its movement through the guide-
socket, not only adjusts the telescope vertically, for any range, but also, by a turning
movement due to the twist of the bar and of the guide-socket through which it
moves, turns the telescope automatically, to make the necessary correction for
drift. It is obvious that a similar twist or helical form imparted to any sight-bar,
whether curved or straight, which moves in a suitable guide, would effect a like
result.
Further adjustment of the telescope, to allow for other correction of aim than
that effected automatically as aforesaid, is obtainable by turning the socket B in
its bearings in the frame Aº, by means of the screw gear operated by the disc C²,
whereby the sight-bar and telescope are turned with the socket so that the said
telescope can be very conveniently adjusted to rectify any error due to the force of
wind moving in a lateral direction.
When the spindle F is turned as aforesaid the spindle J¹ is rotated, by the taper
wheel F³ and the "hundreds" disc I (see Figures 11 and 12) is directly operated
by the said spindle J' and whenever the said disc I completes a revolution the
finger Lenters one of the slots Q' and rotates the star wheel Q, locking piece P,
and pinion O, through a fraction of a revolution; the said pinion O communicates
this imovement to the pinion H' which turns the "thousands " disc H; the thousands
disc H can only be given intermittent movement, for the gap in the locking
disc M will be found, just previous to the entry of the finger L into each of the
slots Q', in the position in which it is shown in the drawing, that is to say a position
in which it offers no obstruction to the movement of the locking piece P; but, when
the finger L has completed the movement of the star wheel Q, the locking disc M
will have turned to bring the circular portion of its periphery into one of the gaps
of the locking piece P, so that the latter after turning for a proper distance with
the parts to which it is connected, has its further movement prevented by the
locking disc M until the finger again comes into readiness to operate it.
I may use as an alternative to the mechanism illustrated in Figures 11 and 12
the arrangement illustrated in elevation and section by Figures 13 and 14, wherein
a short arm J is provided on the spindle J' and a toothed wheel Q is secured to
the pinion H. A spring R held in place by a pin secured to the casing of the
indicator, bears on the teeth of the wheel Q, as shown. Once in every revolution

page_text: 33
of the "hundreds" wheel I and the spindle J' to which it is fixed, the short arm J*
imparts a small angular movement to the wheel Q equal to the pitch of the teeth
of the latter. The wheel Q is geared to the "thousands disc H and operates to
impart intermittent movement to the said disc, in the same manner as the similar
gearing hereinbefore described with reference to Figures 11 and 12. The spring R
prevents the said wheel Q from turning for a greater distance than that between
two teeth as aforesaid, each time it is actuated by the arm J'.
I may, however, substitute any suitable type of rotary indicator for those herein-
before described.
The mechanism whereby the raising and lowering of the sight-bar is effected is
so arranged that while the velocity ratio of the sight-bar D with respect to the
spindle is constant, that of the indicator-spindle J, with respect to the spindle F
is variable, and, if the proper relative proportions of the parts have been observed
in the construction and arrangement of the same, the varied movements of the
bar D which correspond with the different angles of elevation of the gun for
similar increments of the range, will coincide with the constant movements of the
indicator-spindle J' and therefore the range in every position of the gun will be
correctly and clearly shown by the indicator. I thus obtain clear and distinct
indications of all ranges or distances for which the sight-bar is used. This is
obviously an important advantage, readily obtainable according to my invention;
I do not limit this part of my invention to the aforesaid exemplification of the
manner in which it may be put into practice, seeing that there are many other
equivalent arrangements of mechanism whereby a like result can be secured. For
instance, instead of employing an indicating device having the conical spiral
wheel F, I may adopt the alternative construction illustrated in elevation in
Figure 15, in section in Figure 16, on the line of Figure 15, and in another
section, Figure 17, taken at right angles to Figure 16, on the line y y of the latter.
In this construction I fix upon the spindle a disc S with an involute rack S¹
upon the face thereof and arranged to gear with the pinion J sliding upon the
shaft by which the indicating discs are operated, the variation of the radius of
the involute being proportionate to the required variation of linear movement of the
sight-bar for different ranges. Or I may adopt, instead of this modification, an
alternative construction illustrated in Figures 18 and 19, which are views similar
to Figures 16 and 17. In this apparatus I arrange the details in such a manner
that simplicity of construction is attained, by shortening the shaft F, making one
of its bearings in a removable plug F screwed into the frame of the indicator, and
placing the milled wheel F at the side of the sight-bar opposite to that at which
it is situated in Figure 16 for instance. The means whereby, in these modifications
the pinion Jis maintained in gear with the involute rack are the same as are
hereinbefore described with reference to the like devices in Figure 2.
As another alternative I employ the apparatus illustrated in elevation in
Figure 20, sectional plan in Figure 21, and in section in Figure 22, on the line ==
of Figure 21, in which apparatus I use a fusee T to operate a spring-barrel U by
means of a chain V, as in clocks and watches. The fusee, which fixed upon the
shaft takes the place of the coned spiral F3 or of the involute rack S¹, and the
barrel U is preferably provided with numerals upon the portion I of its periphery,
which are visible through a suitable aperture G2 in the indicator casing and are
employed to indicate "hundreds." The fusee T is made with the increase of its
diameter proportionate to the varying increments of movement of the sight-bar.
The barrel U turns on the spindle W which is fixed in the casing of the indicator;
it contains a coiled spring W', of which one end is attached to the barrel U and
the other to the spindle W. A pin U' is placed upon the end of the barrel U to
engage, once in each revolution, with the teeth of a toothed wheel Q journalled
upon a spindle Q' secured to the frame of the indicator. A pinion H* connected
to the wheel Q gears with a toothed segment attached to a plain cylindrical
segment H having the "thousands" figures thereon, which, like the "hundreds
figures, are visible through the opening G³. A spring Q bears upon the wheel Q

page_text: and prevents it from revolving more than the proper distance when moved by the
pin U in the manner hereinafter described. The said spring also ensures that the
thousands" segment shall only take place when effected by
movement of the "
the aforesaid pin.
When the sight-bar D is raised by the rotation of the spindle F, the chain V
which is fastened at the ends to the fusee and the barrel, is unwound from the
latter, which is consequently rotated. Conversely on lowering the sight-bar the
spring W₁ effects the rotation of the barrel U to rewind the chain thereon.
The barrel, in rotating, indicates the "hundreds" and imparts, upon the com-
pletion of every revolution, a partial rotation to the "thousands" segment H by
means of the pin U which coming into gear, momentarily, with the wheel Q
rotates it and the pinion H2 through a small distance, determined by the spring Q².
The pinion H2 thus moved through a small angle, imparts the proper fraction of a
revolution to the cylindrical "thousands" segment H by means of the toothed
segment attached thereto.
As a further alternative I employ the apparatus illustrated in side elevation in
Figure 23 and in section in Figure 24 on the line of Figure 23. In this
modification, F is a spur-wheel fixed upon the spindle F. J is a pinion, secured
to the shaft J and geared with the said spur-wheel. The shaft J' is journalled in
suitable bearings in the frame of the indicator, and has a drum H³ thereon. The
drum is adapted to slide along the shaft J which, except at its ends, is square, or
of such other suitable form in cross-section that when passed through an axial hole of
corresponding shape, in the drum, the latter will turn with, but not independently of,
the shaft. The drum has a helical groove H* upon its periphery, or is otherwise
constructed to engage with a tongue G³ upon the indicator casing as shewn.
H H are scales of ranges for different charges of powder or different projectiles,
arranged helically, in parallel series on the periphery of the drun."
shutter perforated at G³ and adjustable in guides G to expose either series
to view.
G is a
When the shaft J and drum H³ are rotated by the action of the gearing
connecting them with the sight-bar, the drum H³ will turn within the casing like a
screw so as to present successively to the perforation at G in the shutter G', the
graduations of one or other series.
Instead of two scales a single scale or three or more scales can be placed upon
the periphery of the drum if desired.
By arranging the scales helically upon the drum and gearing it to the spindle F
in such a manner that when both are turned the latter will have a greater angular
movement than the former, the scales can be set out at great length, so as to have
clear graduations widely spaced. This is an important advantage.
I sometimes attach a small electric glow lamp to the apparatus for illuminating
the dial of the indicating device to facilitate night sighting.
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. The combination with a curved sight-bar, of indicating apparatus connected
therewith by mechanism which produces a variable velocity-ratio, for the purpose
specified.
2. A sight-bar having a twisted or helical formation so that in moving vertically
it automatically corrects the sight for lateral deviation.
3. The combination with the sight-bar, of a stationary support or frame, and a
guide-socket rotatable therein, with or without the means herein described or other
suitable means for rotating it, substantially as hereinbefore described, for the
purpose specified.
4. The indicating apparatus constructed substantially as herein before described
with reference to Figures 11 and 12, or Figures 13 and 14, or Figures 15, 16,

page_text: and 17, or Figures 18 and 19, or Figures 20, 21, and 22, of the accompanying
drawings, for the purposes specified.
5. The improved sighting and indicating apparatus constructed substantially as
herein before described with reference to Figures 1 to 10 of the accompanying
drawings, or any mere modification thereof, and operating as specified.
Dated this 28th day of February 1894.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.