Improvements relating to Sighting Apparatus for Ordnance.
Year: 1890

page_text: Date of Application, 21st Nov., 1890
Complete Specification Left, 5th June, 1891-Accepted, 11th July, 1891
PROVISIONAL SPECIFICATION.
[Communicated from abroad by DIE ACTIES GESELLSCHAFT GRUSONWERK, of
Magdeburg, Buckau, in the Empire of Germany.]
Improvements relating to Sighting Apparatus for Ordnance.
I, HENRY HARRIS LAKE, of the firm of Haseltine Lake & Co. Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, do hereby declare
the nature of this invention to be as follows :-
This invention relates to a sighting-apparatus which is designed to be used
chiefly with short cannon and mortars, and presents the advantages of enabling the
angle of terrain, that is to say, the difference of level between the cannon and
the object, to be accurately measured and taken into account, and of obviating
the necessity for the use of other instruments designed for this purpose.
The improved sighting-apparatus represented comprises a spirit-level quadrant
or wheel, the pivot-pin of which is held by a clamping screw in a recess provided
on the gun.
The said quadrant or wheel is composed of three discs supported co-axially, the
middle one being formed in one piece with the pivot-pin and serving as a guide for
the two others. Upon the front disc is secured the spirit-level whilst the rear disc
carries upon a suitable arm the back-sight and front-sight it is morcover connected
by screws with a ring upon which a graduated scale is provided.
The movement of the two outer discs relatively to the middle one is effected by
turning two milled wheels upon the axes of which are provided toothed wheels or
pinions which engage with a curved toothed rack secured to the iniddle disc.
In pointing the cannon or mortar the object is in the first place sighted directly
with the aid of the back-sight and front-sight by turning one of the said milled
wheels, then by means of the other milled wheel the front disc is turned until the
spirit-level is horizontal and now the angle of terrain indicated by an arrow can be
read off on the outer graduation. Then through the medium of the last named
milled wheel a turning movement is imparted to the front disc through an angle
which corresponds to the elevation or depression of the gun according to the
firing-table plus or minus the angle of terrain; it is indicated by another arrow
with which the front disc is provided upon the lower graduated scale on the middle
disc which is visible through an opening in the front disc.
When the gun is placed by means of the elevating gear of the gun-mounting, in
such a position that the spirit-level is again horizontal this position will correspond
to the desired elevation or depression according to the firing-table.
The quadrant is provided with a Vernier scale.
The sighting apparatus can if desired, be arranged in such a manner that for
instance the arrow first above mentioned turns and the corresponding graduated
sector is stationary or that the second arrow is stationary and the corresponding
graduated sector turns. Morcover the aforesaid ring becomes superfluous if the
outer graduated sector is provided on the other side, that is to say directly upon
the rear disc.
Also in the bearings of the front and rear discs constructive modifications can
be made which do not affect the characteristic feature of the invention which is the
peculiar combination of a sighting rod and a spirit-level, which are adapted to be
turned relatively to each other, and by means of two graduated sectors permit the
determination of the angle of terrain and, through the medium of the pointing-
gear of the gun, the addition or subtraction of the same to or from the elevation
Recording to the firing-table.

page_text: The advantages afforded by this sighting-apparatus are evident.
With great differences of elevation in the ground considerable errors in the
range would occur by neglecting the angle of terrain, as the trajectory would come
to an end either sooner or later than is assumed in the firing-table.
Moreover the separate measurement of the angle of terrain gives rise to incon
veniences, which are obviated by the present invention.
Dated this 21st day of November 1890.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements relating to Sighting Apparatus for Ordnance.
I, HENRY HARRIS LAKE, of the firm of Haseltine Lake & Co. Patent
Agents, 45 Sonthampton Buildings in the County of Middlesex 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-
My invention relates to sighting apparatus more especially designed to be used
with short cannon such as howitzers mortars and the like.
By my improved apparatus, I am enabled, in the vertical pointing or elevation
of the gun or cannon, to accurately measure and take into account the angle of
terrain, that is to say, the difference of level between the cannon and the object to
be aimed at.
An important feature of my said invention consists in the combination of an arm
or lever carrying the back-sight and the front-sight, and adjustable relatively to the
gun, a spirit-level adjustable relatively to the said arm or lever and to the gun, and
suitably graduated scales, whereby the angle of terrain may be determined, and,
through the medium of the pointing or elevating gear of the gun, the addition or
subtraction of the same to or from the elevation according to the firing table, may
be effected.
In the accompanying drawing 1 have shown how my said invention may be
conveniently and advantageously carried into practice.
Figure 1 is a plan, and
Figures 2 and 3 are side elevations illustrating one form or modification of my
improved apparatus.
Figure 4 is a vertical section on the line ., Figures 1 and 2.
Figure 5 is a side elevation showing another form or modification hereinafter
described.
Like letters indicate corresponding parts throughout the drawing.
a, a', a² are discs mounted co-axially upon a spindle or pivot-pin b, and secured
together by means of springs, washers, and screws, or otherwise. is a pin
firmly secured to or formed on the central disc a', and intended to be fitted into and
secured in a suitable socket upon the gun.
The outer discs a, a² are preferably arranged in suitable recesses provided in the
side faces of the inner or central disc a¹. c is a spirit level firmly secured to the
front disc a, and d is a bent arm carrying a rear or back sight d, and a front
sight, and firmly secured to the rear disc a². e is a spindle supported in a suitable
bearing in the front disc a. ƒ is a milled wheel firmly secured to the outer end of
the spindle e, and is a small pinion firmly secured to the inner end thereof. The
pinion y gears with a toothed quadrant or segment firmly secured to or formed on
the central disc a'. By turning the milled wheel, the disc a can be moved or
adjusted relatively to the disc a' and to the disc a². is a spindle supported in a
bearing in the disc a² in a similar manner to the spindle e and provided at its outer
end with a milled hand wheel j, and at the other end with a suitable pinion j also
h

page_text: gearing with the toothed quadrant or segment h. By turning the hand wheel ; the
said disc a² can be moved or adjusted relatively to the disc af or to the disc a. The
disc ³ is connected moreover by means of screws k¹ which extend through an arc
shaped slot formed in the disc a¹ or otherwise, with a ring klet into the front
surface of the said disc a' so as to be flush with the disc a and provided with a
graduated scale k³.
The movements or adjustments of the two outer discs a and a relatively to the
inner, central or stationary disc a' are effected by turning the milled wheels and j.
The bent arm or lever carrying the sights being rigidly secured as before
mentioned to the rear disc a' the said sights will be moved with the ring k during
the adjustment of the said disc a². is a Vernier scale provided upon the disc u
and adapted to turn with the spirit-level c secured to the latter. The extent of
movement of the said Vernier scale relatively to the graduated scale ³ on the
ring indicates the difference of angle between the sighting-line and the said
spirit-level c. The angle of terrain is therefore indicated when the spirit-level is
placed horizontal and the objective or object to be aimed at is sighted at the same
time.
a' is an aperture formed in the front disc a through which a graduated scale m
provided upon the disc a¹ is visible. An index or pointer is provided moreover
upon the front disc a for indicating upon the said graduated scale m the difference
of direction between the spirit-level and the axis of the bore of the gun.
In using the apparatus for pointing a short cannon, mortar or the like, the
objective, or object to be aimed at is first sighted directly by the aid of the back-
sight and front sight by turning the milled wheel; then by means of the
other milled wheel the front disc a is turned or adjusted until the spirit-level is
horizontal, when the angle of terrain can be read off by means of the Vernier
and graduated scale ². The said front disc a is then turned or adjusted by means
of the milled wheel to move the index or pointer upon the graduated scale m
through an angle corresponding to the required elevation or depression of the gun
according to the firing table, plus or minus the angle of terrain.
When the gun is placed by means of the elevating-gear of the gun-mounting in
such a position that the spirit level c is again horizontal, this position will correspond
to the desired elevation or depression according to the firing table.
In the modification shown in Figure 5 I dispense with the aperture at in the
front disc a, the graduated scale m on the disc a, and the pointer or index n on the
said disc a, and provide on the outer rim of the stationary or central disc a¹ an
index or pointer o.
In using this modification of my apparatus the zero on the graduated scale k' on
the ring is brought in line with the index or pointer o after the angle of terrain
has been determined in the hereinbefore mentioned manner. The sighting-line is
thus brought parallel with the axis of the bore of the gun, and the Vernier scale
indicates on the graduated scale k the difference of direction between the axis of
the said bore and the spirit-level. If the disc a be moved or adjusted to make this
difference equal to the angle of direction (the elevation being according to the
firing-table plus or minus the angle of terrain) the gun will be in the right position
for firing when the gun is placed in such a position that the spirit-level is brought
horizontal by means of the pointing or elevating-gear.
It is obvious moreover that I can somewhat further modify the construction of
my improved sighting apparatus without however departing from the nature of my
said invention. For instance the Vernier scale is sometimes placed upon an
adjustable part, and the graduated scale k² upon a stationary part, or the
pointer or index n is arranged upon a stationary part, and the graduated scale in
upon an adjustable part. By arranging the graduated scaleupon the outer
surface of the rear disc a² the ring can be dispensed with.
The advantages afforded by my improved sighting device are obvious, as with
great differences of elevation in the ground considerable errors in the range would

page_text: occur if the angle of terrain were neglected, through the trajectory terminating
either sooner or later than is assumed in the firing-table.
Having now particularly described and ascertained the nature of the said inven
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondents, 1 declare that what I claim is:-
First. A sighting apparatus for ordnance, comprising an arm or lever carrying
the back and front sights and adjustable relatively to the gun, and a spirit-level
adjustable relatively to the said arm or lever and to the gun, for the purposes
above specified.
Second. A sighting apparatus for ordnance, comprising a disc, quadrant or the
like adapted to be secured to the gun, and other discs, quadrants or the like
adjustable relatively thereto and to each other, provided respectively with a spirit-
level and with an arm or lever carrying the sights, substantially as, and for the
purposes, specified.
Third. The improved sighting apparatus constructed substantially as described
with reference to Figures 1, 2, 3 and 4, or to Figure 5 of the accompanying
drawing and operating as, and for the purposes, set forth.
D. 1.
1801
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.