A Trench Periscope sighting attachment for the SMLE rifle
...
Left: the front face of the prism
viewed over the rear-sight
from the muzzle of the rifle.
Below: the sight picture.
Looking up through
the base of the prism
over the sights
With the firer standing on the fire-step, the rifle would, most commonly, be rested on the trench parapet, ideally on a sandbag,
or similar, for stability and to protect the right forearm, then held with the right hand holding the wrist of the
butt-stock and with the fore-finger on the trigger in the usual way.
The left hand would be used to grip the butt-plate, with the left fore-arm above the head.
Sighting could then be accomplished by tilting the head back and looking through the underside of the prism.
In March 1915, Youlten was granted a further patent for a modified prism design,
now additionally in the name of the company Periscopes and Hyposcopes Ltd.
In January of that year he had already patented a design, no. 480,
for a hyposcope which could be "attached to the backsight of a machine gun".
3496.
Periscopes & Hyposcopes, Ltd.,
and Youlten, W. March 4. Sighting - accessories:-
Consists in forming a hyposcope of a single prism having (1) a front face normal
to the line of sight, (2) a first reflecting-surface which is total-reflecting,
and (3) a second reflecting surface which is silvered or otherwise converted
into a mirror. In the prism shown in Fig. 2, the reflecting surfaces 19, 18
make angles of 60 degrees and 90 degrees respectively with the front face 17,
and the ray is deflected through 60 degrees. In the prism shown in Fig. 6, the
reflecting-surf aces 24, 23 make angles of 45 degrees and 112½ degrees
with the front face 22, the ray being deflected through 45 degrees. A prism
constructed according to this invention may be combined with other reflecting-surfaces
which first deflect the sighting-line sideways and then backwards.
Youltens' inventive ideas for sighting aids were prolific, and he subsequently designed an elaborate rifle optical system along the lines of the Lattey, Neil and Gibbs Galilean products, but again also for possible utlisation on a machine gun.
This unit received its patent grant in August 1915.
11,227. Youlten, W. Aug. 3. [Cognate Application, 1163/16.]
Sights; sighting-accessories: -
Relates to optical sights of the kind in which a half object lens or com¬bination,
and a half eye¬piece lens or combination are so mounted with re¬spect
to the Ordinary sights that an open sight can be taken and, at the same time,
a magnified image can be seen. Accord¬ing to the invention the object lens
is mounted in a carrier adapted to be clipped or otherwise attached in close
proximity to the foresight, and the eyepiece lens is mounted in a carrier adapted
to be attached to the V or equiv¬alent part of the backsight so that it
moves there¬with. Figs. 1, 3, 4, 5, and 6 show the invention applied to
a service rifle. The eyepiece lens t, Figs. 3 and 4, is mounted in a carrier
s provided with clips 2, 3 and a screw, 4 for securing it to the ordinary V
sighting plate, in such a position that the bottom edge of the lens is level
with the top edge of the sighting-plate. The object lens h, Figs. 5 and 6, is
mounted in a carrier g fitting, by means of a dovetail joint, in a base-plate
formed with a clip a, b for securing it to the gun. Figs. 8 and 9 show a method
of securing the eye lens 13 to the backsight of a machine gun. The lens is mounted
in a carrier 12 which is attached to a plate 8 adapted to be clipped to the
sighting-plate. The lenses may be adjustable. A hyposcope may be combined with
the eye lens.
See also the Chandler Periscopic Hyposcope Lee-Enfield rifle adaptation
For Enfield and Lee-Enfield training rifle accessories and adaptations, see also: Miniature calibre adapters and conversions
Should you have an unusual Lee-Enfield small-bore rifle conversion and be willing to provide photographs, then we would be grateful to receive details.
Full acknowledgement of any published images would be afforded.
email the editor: HARC-MRL@rifleman.org.uk
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