The Youlten Hyposcope for the SMLE rifle

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THE YOULTEN HYPOSCOPE

A Trench Periscope sighting attachment for the SMLE rifle

Below: the adapter viewed from the right-hand side of the butt-stock

During the First World War, this device was advertised for private purchase at £7-1s-0d (£7.05), at a time when a high-quality target-standard "Long" Lee-Enfield rifle could be purchased complete for between £7 and £8. The new " short" rifle was being sold, by the various manufacturers, to the Government for little over £3.

Youlten applied for his first patent in 1914, and it was granted on October 2nd.

20,439. Youlten, W. Oct. 2.
Sighting - accessories: Consists in forming a hyposcope of a single double-reflecting prism, Fig. 2, having a vertical rectangular face 5 opposite and at right-angles to the line of the sights, lower and upper rectangular totally-reflecting faces 3, 1, a rectangular face 6 oppo¬site the eye of the marksman, and two trape¬zoidal side faces, the prism being enclosed in a casing 7, Fig. i, which leaves the faces 5, 6 exposed and is preferably mounted so that it can be raised and lowered behind the V or other sight. The casing 7 is provided with a retaining-strip 8 of angle section for holding the prism in position, and with hinged flaps or shields 12, 13 for the faces 5, 6. A geometrical construction for determining the shape of the prism is described.

The patent for the finished article was granted just after Christmas in 1914

24,687. Youlten, W. Dec. 28.
Sights; sighting - accessories:-

Relates to means for attaching hyposcopes to rifles or other small-arms, and consists in the combination of a clip 7 adapted to be passed round, and clamped to, the stock of the rifle near to the butt end, and a stem 12 carrying a prismatic or other hyposcope 18 cen¬trally behind the sights, the hyposcope deflecting the line of sight down¬wards over the butt. The stem 12 is prefer¬ably hinged to the clip 7 and provided with means for locking it in the raised or lowered position. The stem may be telescopic, or may consist of a system of levers. The Provisional Specification also states that the backsight may be dispensed with, range indications being provided on the stem and a suitable sighting-mark provided on the hyposcope , and also describes a construction of hyposcope comprising a wide upper mirror and one or more smaller reflecting-surfaces at a lower level.

The unit came in a small wooden box, and could be quickly attached to a No.1 SMLE rifle or indeed any Enfield derivant with similar stocking dimensions. An instruction sheet, shown in greater detail in a lower image, was glued to the inside of the lid in customary contemporary fashion.

...

The lid of the box carried the now rather indistict stencilling

.......................YOULTEN'S

............RIFLE BUTT HYPOSCOPE

....................SUPPLIED BY

......PERISCOPE HYPOSCOPES LTD

.................WESTMINSTER S.W.

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.

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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THE YOULTEN HYPOSCOPE A Trench Periscope sighting attachment for the SMLE rifle