An Improved Collimating Device or Apparatus, chiefly designed to Facilitate the Pointing or Alming of Guns.
Year: 1893

page_text: COMPLETE SPECIFICATION.
An Improved Collimating Device or Apparatus, chiefly designed
to Facilitate the Pointing or Alming of Guns.
I, LOUIS PIERRE HENRY DE PLACE, of 95 Boulevard Beaumarchais, Paris,
in the Republic of France, Captain, 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 a novel device or apparatus which is chiefly designed
to be used in place of the ordinary rear-sight and pointing-level of guns.
In the accompanying drawings,
Figure 1 is a side view, and
Figure 2 a front view, both partly in vertical section, showing one form of my
improved sighting or collimating device or apparatus applied to a gun.
Figure 3 is a plan of the upper and lower horizontal platforms or tables of the
apparatus.
The instrument is mounted on a hollow rod or stem Y of oblong or rectangular
form in transverse section, which is fitted into a recess V formed in the breech of
the gun. The width of this rod in the direction of the axis of the gun ensures its
having sufficient rigidity to prevent its being thrown out of truth by the recoil of
the gun.
The improved sighting or collimating device remains on the gun during the
discharge.
The hollow rod or stem Y carries the platform L in which is formed a central
hole to receive the rod or stem D of an upper platform C which platform is so
arranged that it may be adjusted or turned about its axis by the rotation of a
screw E provided with a milled head; the upper platform C is provided on one of
its edges with graduations extending to 20° on each side of zero; while the opposite
edge extends beneath a projecting piece or bracket K which is secured to the
platform L and in which is fitted a clamping-screw H, whereby the upper platform C
may be secured in any desired position. The lower platform is provided with a
pointer I indicating on the graduation of the platform C the azimuthal angle given
to the whole instrument. The platform C, which is called the drift-correcting or
wind-gauge platform, is preferably made of bronze, as are the other parts of the
sighting or collimating device, and carries the standard B, which is preferably cast
in one piece therewith, and which has the form shown in Figure 2.
THE COLLIMATOR.
The collimator proper A is composed of a glass tube completely enclosed in a
thin casing of sheet-metal. This glass tube is terminated by two convex surfaces
one of which is at the focus of the other, as in the "Stanhope" lens. The rear
part a serves as the eye-piece and is held in a bronze shell T which does not
completely encircle it, the side at P, Figure 2, being open in order to facilitate the
aiming of the gun as hereinafter indicated. The shell T is secured to a pivot S
which extends through the standard B. The other end of the glass tube is
provided with an arrow or line in black or red enamel, situated in an exactly
horizontal plane. The metal casing which encloses the tube, carries at this end :-
1st. a small stud z which works in a groove R and causes the collimator to follow
the standard B when it is turned about the pivot S of the shell T; 2nd a pointer P
which extends behind the transparent graduated limb N, as shown by dotted lines
in Figure 1, and indicates the angle of elevation thereon.

page_text: leaves the surface of the glass limb N during the angular movements imparted
to it.
THE RANGE AND DRIFT OR DEVIATION LIMB.
The limb M is made in the form of a segment of a hollow cylinder, having its
centre at the highest point of convexity of the rear face of the collimator. On the
concave surface of this limb there are engraved degrees extending from 0° to 55°
towards the lower part, and from 0° to 10° towards the upper part, the zero corre
sponding to a perfectly horizontal aim, according to the axis of the gun. This limb
and the limb N are not in a vertical plane but are inclined from left to right in such a
manner that the correction for drift is effected automatically in the operation of
pointing the gun.. As is well known, the rotation of the projectile about its axis
causes it to deviate from the line of fire, always in the same direction, by an amount
which may be easily calculated according to the range.
The inclination of the said limbs is so calculated that, whatever be the range, it
is not necessary to take into account the deviation of the projectile due to the
drift. (This refers to the drift due to rotation of the projectile, the correction for
deviation due to the wind being effected by means of the platform C.)
The graduations on the limbs are preferably obtained as follows, that is to say ;-
A microphotographic scale is obtained by photographing a scale say 10, 20, 30, or
other suitable number of times larger, either directly upon the glass, or preferably
on a collodion film or on a sheet of sensitized horn or mica; these flexible plates,
when such are used, being placed between two suitable glasses.
The use of this collimating device in the horizontal and vertical pointing of guns
will be readily understood.
The operator brings the pointer P of the collimator over the angle indicated for
the range, the allowance for drift or deviation being provided for at the same time
by the inclination of the limb M, the pin S being free to slide longitudinally in the
piece B. On applying the eye to a the operator observes the horizontal cross-line
in the collimator; this line blends with the graduation on scale M, showing the
angle of elevation at which the pointer has been stopped; opposite to this
graduation, the glass limb N may bear the range expressed in metres; this scale,
however, is not shown in the drawings. The operator now works the pointing-
mechanism of the gun in such a manner as to bring the cross-line to the height of
the object aimed at; this operation is very easy because, the tube of the collimator
being very thin at the right hand side, it only needs a small amount of practice to
divide the pupil of the eye in two and to observe the field and the cross-line at the
same time.
When the eye is placed very near to the collimator, the pupil is sufficiently
extended for the cross-line to appear to cover the object aimed at. The cross-line
in black or red enamel should be placed a little on one side of the principal focus
of the curved rear surface of the collimator so as to facilitate the superposition of
this cross-line and of the object sighted. The upper or drift-correcting platform C
is used when, for one reason or another and once for all at the commencement of
firing, it is desired to increase or diminish the allowance for drift.
My improved collimating device has the great advantage over collimators with
lenses, of being easily cleaned, having great strength, and above all of not being
liable to be obscured by aqueous vapour, which renders the use of hollow sighting
devices and sighting telescopes difficult.
I can, moreover, apply my collimator or sighting device to the pointing-levels of
guns to bring the same into an horizontal position and thus replace the spirit-level
of such instruments by the adjustment about a fixed point on or near the gun-
carriage, and this, whether the instrument be direct reading or not.
For this purpose a fixed point is taken on the gun-carriage, mounting or the like
such that the gun is absolutely horizontal when the gunner, by operating on the

page_text: pointing mechanism, causes the line formed by the axis of the telescope, when at a
previously determined graduation, to pass through the said fixed point.
In other words, train the gun, on which the collimator is fixed, into such a
position, that the axis of the said gun is absolutely horizontal, which horizontality
may be verified in any convenient manner; this done, observe with the telescope a
point on the gun-carriage, mounting or the like and mark the said point in such
a manner that it may be readily found; the line of sight passes through a certain
graduation on the range limb which graduation is to be carefully noted; it is
evident that, if at any time it be desired to place the axis of the gun along a
horizontal line, it is only necessary to adjust the telescope to the previously noted
graduation on the range limb and then cause the line of sight to pass through the
fixed point; when the gun is so trained, it follows that its axis will be absolutely
horizontal.
Instead of the axis of the gun, any given straight line may be drawn on the said
gun and be brought into an absolutely horizontal position at will, in the manner
above described. My improved collimator may, moreover, be applied to other
instruments or apparatus turning about a fixed point, in the manner above set forth,
to adjust the same to any position to which it has previously been adjusted.
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 :-
First. A collimating device by means of which the angle or other indication of
the range may be read directly, either through a transparent graduated limb (N)
or by reflection upon a non-transparent graduated limb (M), substantially as
hereinbefore described.
Second. The provision of suitable means whereby allowance for drift or other
lateral deviation is made by the same movement which effects the adjustment for
determining the angle of fire, substantially as hereinbefore described.
Third. The employment of a fixed mark on the gun-carriage or mounting or
other suitable support, permitting the use of the collimator as a pointing-level when
the object to be aimed at is hidden, substantially as described.
Fourth. The use of a scale reduced by microphotography, substantially as
described, and for the purpose specified.
Fifth. The use, in instruments for the measurement of angles, distances, surfaces
or volumes, of a collimator movable in front of a fixed limb, or of a movable limb in
front of a fixed collimator, which limb is graduated by microphotography or
otherwise, substantially as described.
Sixth. The improved apparatus constructed substantially as described with
reference to the accompanying drawings and operating as, and for the purposes,
above specified.
Dated the 20th day of — 1902
D. YOUNG & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicant.