Improvements in Sights for Guns.
Year: 1891

page_text: COMPLETE SPECIFICATION.
[Communicated from abroad by BRADLEY ALLAN FISKE, of the Beresford, New
York City, United States of America, Lieutenant United States Navy.]
Improvements in Sights for Guns.
I, WILLIAM ROBERT 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 and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :-
The invention relates to a telescopic sight for ship's guns and consists more
particularly in the construction of said sight and its combination with the gun.
In the accompanying drawings,
Fig. illustrates diagrammatically a gun disposed with the axis of its bore
parallel to the plane of the ship's deck and provided with a shield, upon which is
mounted my aforesaid telescopic sight, which is shown in two positions; namely,
with the axis of the telescope parallel to the gun axis, and with the axis of the
telescope placed at an angle to said gun axis.
Fig. 2 represents the same parts as in Fig. 1, and shows how the telescope is
brought into horizontal position after it has been adjusted at an angle, as aforesaid,
by the rolling or pitching of the vessel, whereby the deck assumes an inclined
position.
Fig. 3 is an elevation of my telescopic sight showing certain parts broken away
and in partial section.
Fig. 4 is a face view of the graduated disk and stationary surrounding limb
which is graduated in degrees and fractions.
Similar letters of reference indicate like parts.
Referring first to Figs. 1 and 2, A. represents a portion of a ship's deck. B is the
gun, the trunnions C of which are mounted upon any suitable carriage D supported
on a slide which carries the usual protecting shield E, through an opening in which
the gun extends. Upon a side of the shield is secured a bracket F, upon which is
secured the supporting base G of the instrument. His the telescope having
trunnions which are received in suitable bearings carried by standards K which
rise from the base G. Extending downward from the middle part of the telescope H
is a projection L, the lower extremity of which is cut away to form a vertical flat
surface, against which surface bears the point of the adjusting screw M. The
Screw M passes through a threaded standard N upon the base G; and upon its
shaft carries a flanged disk O, and also outside of said disk a milled head P, by
means of which head P said screw is turned. Supported by bars Q projecting from
the standards K, is an arc-shaped limb R, which has its inner periphery in close
proximity to the circumferential edge of the disk O. Connected to the projection L
and extending downward below the same, is an arm S to which is secured one end
of a coiled spring T; the other end of said spring being fastened to a hook, or
otherwise secured upon the post N.
The telescope H is of the usual kind for field work and is provided with suitable
cross-hairs. Upon the disk O is marked first a zero point, and then follow regular
graduations, suitably marked, as shown in Fig. 4, which indicate yards of range.
The markings upon the limb R represent degrees of elevation or depression of the
elescope.
The general operation of my aforesaid apparatus will be understood from Figs. 1
nd 2. Referring first to Fig. 1, here the axis of the bore of the gun represented
y the dotted line a a, is shown to be parallel to the plane of the deck.” A¨`
The

page_text: t
line of sight of the telescope H (full lines) is shown by the dotted line 6, which is
parallel to the line a a.
Let it now be assumed that the gun is to be given a certain elevation necessary
to carry the projectile over a given range or interval between the said gun and the
target. Ordinarily this is done by adjusting a vertically moving sight bar supported
upon the breech of the gun so that a notch thereupon will be properly elevated,
and then lowering the breech of the gun until the line of sight of the person directing
said gun includes the bottom of said notch, the top of a fixed sighting point located
upon the gun body and the object. When this occurs, the muzzle of the gun will
have been raised over a certain angle; or in other words, the gun will have been
elevated over an angle sufficient to cause the projectile to travel over the given
range or interval. In practice, it is customary to mark the ordinary sight bar both
in degrees and fractions, so that the gun may be set at any desired elevation, and
also for yards of range corresponding to the elevation in degrees. So that by
means of said sight-bar, the gun may be adjusted in elevation to any desired angle,
or for any desired range.
The objections to this form of sight upon ships' guns are numerous.
Inasmuch
as the sight-bar is upon the gun itself, it partakes of all motions of the gun;
such as the recoil. The bar after adjustment is, therefore, liable to displacement,
and in fact is usually re-adjusted for each shot. The person sighting the gun
is obliged to stand at a distance from the breech, and hence from the sight
bar thus greatly increasing the difficulty of bringing the rear sight and front
sight of the gun and the object into line. These difficulties are much enhanced
when the ship (as is invariably the case at sea) is rolling or pitching. The
person sighting the gun must then maintain his own equilibrium, and in addition
must seize the exact moment when the sights come in line with the object, to
fire. The consequence is that accurate firing in a sea-way has become largely
a matter of individual skill, which may require high development not merely
by reason of the difficulties before noted, but for the elimination of personal equation
of error, as well as for its employment under the exciting conditions of actual conflict.
By my present invention, the aforesaid difficulties are greatly reduced, and to a
large extent overcome.
I employ primarily the rolling or pitching of the ship itself to give to the
gun the necessary elevation; the piece being normally laid with the axis of its
bore parallel to the deck. Or, if the extent of angular movement of the deck
is not sufficient to carry the gun over the whole desired angle of clevation, then
I give to the gun by the ordinary elevating gear, a certain initial angle of
elevation which is made sufficiently great to allow of the ship's movement com-
pleting the whole desired angle. The gun is sighted by means of a telescope
not supported on the gun, nor partaking of the gun's recoil, but preferably upon
the shield E. 1 sight the gun in the following manner. The line of sight b b
of the telescope, the axis of the bore a a and the deck being parallel, the gun
is trained laterally upon the target; and the telescope being attached to the
shield, is so trained at the same time. The observer at said telescope notes
the fact that the target, as the ship rolls, is seen at the intersection of the
cross-wires. The object end of the telescope is then depressed by the means
hereinafter detailed over an angle which is to equal that of elevation of the gun
necessary to cause the projectile to travel over the distance or range between
gun and target. The position of the telescope when so depressed is indicated
by the dotted lines in Fig. 1, and the direction of its line of sight by the line c c.
The observer still keeping his eye at the telescope, then watches for the
target once more to appear at the intersection of the cross-hairs. This obviously
will occur when the deck A, and hence the axial line a a of the gun, assume
an angle equal to that at which the telescope has been placed: Or in other
words, when the telescope H becomes horizontal, as indicated in Fig. 2, then
the axis of the bore a à will stand at the proper angle to give the projectile

page_text: the required range. The observer therefore, as soon as he notes the coming
of the target upon the intersection of the cross-wires, presses the firing key and
discharges the gun.
:
The
Referring now to Figs. 3 and 4, I have here illustrated the mechanism which
practically supersedes the ordinary sights on the gun. It will be plain that
when the milled head P is turned in one direction, the point of screw M pushing
upon the extremity of the projection L, causes the object end of the telescope
to rise but when said milled head is turned the other way, the spring T
acting upon the arm S and projection L, causes the object end of the telescope
to descend. Therefore the telescope may be elevated or depressed by turning
said head P, which is conveniently placed to the hand of the operator.
zero mark on the disk is so placed that when it coincides with the zero
mark on the limb R, the line of sight of the telescope is parallel to the deck.
The limb R is marked to represent degrees of angular motion of the telescope:
and upon the disk O are marked the ranges which correspond to those angles
and which will be given by the gun which the apparatus is to control.
Thus
in Fig. 4, it is shown that at an angle of elevation of two degrees the range
will be 2200 yards. At an angle of one and a half degrees, the range will be
about 1675 yards. At one degree, 1075 yards, and so on. If, therefore, we
wish to adjust the telescope for a range say of 2200 yards, the milled head P
is turned until the mark 2200 comes opposite the zero mark on the limb R.
The spring T acting on the projection L, will then have depressed the telescope
over an arc of two degrees. A similar operation is performed for any other
range mark on the disk O: it being necessary simply to bring the proper range
mark into coincidence with the zero mark on the limb R to know that the
telescope has been set at such an angle as that when the object appears at the
intersection of its cross-hairs, the gun itself located in proximity to that telescope
will be at the same angle; or in other words, be so adjusted as to throw its
projectile over the range indicated by the disk.
In case the ship is not rolling or pitching sufficiently to give to the gun the
desired elevation, then, as already described, an initial elevation is given to the
gun itself; say, for example, one degree, when the total required angle is two
degrees. It will be obvious then that the necessary angular movement of the
telescope will be only one degree for a range, say of 2200 yards. In such case,
therefore, the 2200 mark on the disk O is not moved around to the zero point
on the limb R, but to the one degree point on said limb. Or in other words,
to the point representing the initial elevation given to the gun whatever it
may be.
By the word "deck" is herein meant that part of the deck on which the gun
moves and which in modern war ships is always a plane surface.
The line from the gun to that point of a target situated at the same height above
the water as the gun is here assumed as the line of sight, and the line of sight is
thus assumed to be horizontal. But it is evident that no appreciable error is intro-
duced if the line of sight be not exactly horizontal, but intersect a target on the
water at any point, for the projectile will simply strike the target higher or lower
according as the line of sight is higher or lower. It is evident that for night firing,
the cross hairs may be made incandescent by an electric current, as is done with
astronomical telescopes, thus avoiding the necessity for the complicated electrical
night sights used in all the navies of the world.
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 correspondent I declare that what I claim is :-
1. A telescopic sight for ships' guns, substantially as herein shown and described.
2. The combination of a sight tube movable on a transverse axis, a screw
operating to cause such motion, a graduated disk index carried by said screw and

page_text: an index or scale plate in proximity to said screw index, the said disk index and
scale plate index being graduated, the one in angles and the other in ranges
corresponding thereto.
Dated this 8th day of April 1891.
HASELTINE, LAKE & Co.,
45, Southampton Buildings; London, W.C., Agents for the Applicant.