An Improved Method of Practising the Sighting and Aiming of Ordnance, and Apparatus in Connection therewith.
Year: 1888

page_text: 1888
Date of Application, 15th Oct.,
Complete Specification Left, 27th July, 1889-Accepted, 15th Nov., 1889
PROVISIONAL SPECIFICATION.
An Improved Method of Practising the Sighting and Aiming of
Ordnance, and Apparatus in Connection therewith.
I, LEONARD DARWIN, of No. 18 Wetherby Place, South Kensington, in the County
of Middlesex, Captain in the Royal Engineers, do hereby declare the nature of this
invention to be as follows:-
My invention relates to a method of practising the sighting and aiming of ordnance
without incurring the danger and expense of firing, and to apparatus employed in
carrying this method into effect.
For this purpose, on the gun with which practice is to be made, 1 fix a camera
and an object point against which the photographic plate is pressed to determine a
zero point for measurement on the picture.
The gun being elevated and trained for hitting a target or other distant object,
the trigger is pulled opening the shutter of the, camera and a photograph is taken
which shews the target or object and also the object point above mentioned. By
observing on the photograph the position of the image of this object point relatively
to that of the target or distant object, the accuracy of the sighting and aiming can be
readily tested.
The object point and plate are preferably so fixed that the plate is prependicular to
the line joining the object point to the optical centre of the lens. A vertical line
drawn on the picture through the zero point can then serve as a scale of tangents of
elevation.
In order to determine the vertical line on the picture, the object aimed at
may have a suitable mark either vertical or horizontal to make its image on the
photograph.
At sea the horizon will usually serve for this purpose, and in many cases a spirit
level may be used to determine the vertical.
The photograph taken may serve also for determining range in the following
manner. The object aimed at, as for instance a ship, may have on it marks at known
distances apart. The positions of the images of these on the photograph will serve to
indicate the range of the object.
In practising on land, where both the gun and the object are stationary, it is not
necessary to take a photograph, as the positions of the various points can be marked
on the ground glass of the camera.
Dated this 15th day of October 1888.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
An Improved Method of Practising the Sighting and Aiming of
Ordnance, and Apparatus in Connection therewith.
1, LEONARD DARWIN of No. 18 Wetherby Place, South Kensington in the County
of Middlesex, Captain in the Royal Engineers, 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 a method of practising the sighting and aiming of ordnance
without incurring the danger and expense of firing, and to apparatus employed in
carrying this method into effect. For this purpose, on the gun, with which practice
is to be made, I fix a camera and an object point against which the photographic
plate is pressed to determine a zero point for measurement on the picture. The gun

page_text: being elevated and trained for hitting a target or other distant object the trigger is
pulled opening the shutter of the camera and a photograph is taken which shews the
target or object and also the object point above mentioned. By observing on the
photograph the position of the image of this object point relatively to that of
the target or distant object, the accuracy of the sighting and aiming can be readily
tested. The object point and plate are preferably so fixed that the plate is perpendi-
cular to the line joining the object point to the optical centre of the lens. A vertical
lino dawn on the picture through the zero point can then serve as a scale of
tangents of elevation.
In order to determine the vertical line on the picture, the object aimed at may
have a suitable, imark either vertical or horizontal to make its image on the
photograph. At sea the horizon will usually serve for this purpose, and in many
cases a spirit level may be used to determine the vertical.
The photograph taken may serve also for determining range in the following
manner. The object aimed at as for instance a ship, may have on it marks at known
distances apart. The positions of the images of these on the photograph will serve
to indicate the range of the object. In practising on land, where both the gun and
the object are stationary, it is not necessary to take a photograph, as the positions of
the various points can be marked on the ground glass of the camera.
.
Fig. 1 of the accompanying drawings is a longitudinal section. Fig. 2 is a sectional
plan and Fig. 3 is a transverse section of a convenient form of camera for operating
according to my invention. The case H of the camera may be made as shewn of
sheet metal having a rectangular section with its upper side B sloping upwards so as
to give room at the end for a plate of some height. At the front are fixed suitable
lenses C, and at the back there is fixed in the line of the optical axis a small triangular
sight Dagainst which the plate is pressed when the back door E is closed and
secured by a spring catch F.
It is also of advantage to provide an upper central sight G and two lateral
sights H H equidistant on each side of G. The camera being mounted on the gun
trained on a front pin K as an axis and adjusted for level by screws L so that the
optical axis is parallel with the line of sight of the gun, the photographic plate is
slid into the door with its covering shutter and this shutter being withdrawn the
door is closed pressing the plate against the sight D and also against or close up to
the other sights G and H. The lens cap being then removed, the target or object
aimed at produces its image on the plate, which at the same time is marked by the
sights D. G and H. The horizontal and vertical axes of the plate being determined
from the images of these sights, the position of the image of the object aimed at
relatively to these axes shews the error in the aiming of the gun. Obviously, when time
is not an object, the apparatus may be used without photographing, the position of
the sights and of the image being marked in pencil on a frosted glass plate.
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The herein described method of practising sighting and aiming of a gun without
firing it, by mounting on the gun a camera and obtaining an image of the object
aimed at along with determining sight marks.
2. For operating in the manner above referred to, a camera adjustable on a gun and
provided with suitable sights, substantially as described.
Dated this 4 ..
T1000
ABEL & IMRAY,
Agents for the Applicant.