Z.8421/2 "Dioptrion" lantern showing method of mounting. Sectional scale drawing. The iso-candle is based on an average lamp light output through life from a 400 watt OSRAM H.P.M.V. lamp. (13,600 lumens) . 250 w. 400 w. Directional intensity ratio 2.5 2.5 Light above horizontal 20% 20% Light output ratio 70% to 70%

"DIOPTRION" LANTERN Upper refractor and interior of lantern seen from underneath. The non-magnetic plate carrying the magnetic deflector has been released from its normal position (parallel to the body) and allowed to hang down, so the wiring and terminal block can be seen. (Lower refractor removed).

"Dioptrion" Lantern.

Use Main road lighting; 25 ft. mounting height; spacing 120 ft optimum, but can be used up to 150 ft. maximum; road width 30-40 ft. For roads over 40 ft. in width this lantern, with its horizontal burning lamp, will give better results than would be obtainable from a lantern with a vertical burning light source.

Lamp

Mounting Side entry. Requires a minimum length fo 12 in. horizontal unthreaded 1¼ in. gas barrel When fully home, two 7/16 in. Allen type grub screws grip the barrel.

Lantern Body Die-cast light alloy. The body carries the lampholder, terminal block, cable clamp, heat-resisting wiring, lamp steady, reflector plate and magnetic deflector. A water baffle and drainage hole are provided to carry off any water running along the bracket. An earthing screw is provided.

Lampholder Porcelain G.E.S. Wired with heat-resisting wire to a terminal block.

Over Reflector Immediately above the lamp and hinged at the holder end is a non-magnetic polished reflector. Release of teh catch holding this allows it to swing down, thus giving access to the bracket entry and terminal block.

Magnetic Deflector On the reflector plate is mounted the magnetic deflector which is in series with the lamp and consumes 1 watt. The reflector plates serves the dual purpose of reflecting light and preventing rising hot air from over-heating the deflector. The use of a magnetic deflector enables a MA/H lamp with a hard glass outer jacket to be operated at the same efficiency as the normal MA/V lamp.

Optical System
The pressed prismatic refractors are made of heat-resisting glass and are smooth externally except for three steps in the lower refractor.

The upper refractor is held by the body, and the lower refractor is supported by a steel rim which is held at each end by cantilever springs. Catches on each spring give a toggle action, while the catch at the bracket end can be unhooked, allowing the lower refractor to swing down sogiving access to the lantern interior. A special gasket cemented to the lip of the lower refractor ensures a weatherproof seal when the lantern is closed.

Weathering Finish The alloy used is specially selected for its resistance to corrosion. Further protection is obtained by the use of a suitable primer, undercoat and matt aluminium finish top coat.

Erection Instructions Full erection and focusing instructions are enclosed with each lantern.

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