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esla bi-multi group "a" two-way 165° 7½°

Genre: Wing type lantern

The wing type lantern was invented by Haydn Harrison in the early 1920s. Typified by its simple construction and unique shape, Harrison's design collected some of the flux emitted by the upper parts of a symmetrical point light source, and fashioned it into various beams which were used to illuminate the road surface. The flux emitted in the lower hemisphere of the light source was uncontrolled, producing a circular pool of light below the lantern. Therefore the lantern illuminated both the road surface and its immediate environment.

The wings of the lantern controlled the number and angles of the beams. Given the huge number of different lighting requirements of roads and their environs, a large number of differently configured wing type lanterns were produced. These differed in the number of wings and the angles of the beam; it wasn't uncommon to find many different lanterns lighting a single stretch of road.

The first type of wing lantern, due to Harrison, used facetted, mirrored glass pieces stuck to a cast-iron frame (and he held the patent for the method of arranging and sticking them). Other manufacturers also produced wing type lanterns; but elected to use polished enamel surfaces, curved etched and fluted glass, and/or glass strips held by metal lugs in order to side-step the patent.

Whilst the utilization factor was lower than other lanterns (due to little flux being collected above the lantern), and glare from the totally exposed bulb was an issue, wing type lanterns became popular for their sheer robustness, minimal number of parts and cheapness.

The design of the wing type lantern changed little over the next thirty years. Although open lanterns were frowned upon by the mid-1950s (as no protection was afforded to the bulb nor the reflective surface so both got dirty and required regular cleaning), wing type lanterns were still being installed in the 1960s; but in the end, discharge lamps and the benefits of enclosed lanterns saw their eventual downfall.

Name: ESLA Bi-Multi Group "A" Two-way 165° 7½°
Date: Circa 1920s - 1950s
Dimensions: Length: 8 ½", Width: 10", Height: 9 ½"
Light Distibution: Uniform Distribution (BS 307:1927)
Lamp: 40-150W GLS


The Bi-Multi, the first wing-type lantern, was invented in 1923 by Haydn Harrison. Unable to find a manufacturer for his new lantern, he approached schoolfriend Herbert Biggleston who owned a foundry in Canterbury. Electrical Street Lighting Apparatus (ESLA) was founded shortly afterwards.

The Bi-Multi was a revolution. All the other manufacturers were making over complex, multiple part frame-type lanterns, modifications of early gas style fittings. Harrison's genius was to simply remove all the complexity and reduce a lantern to a bulb, focusing mechanism and simple reflective optical system.

As epitomized by the wing type lanterns, the original Bi-Multi was made in many variants, each characterized by different number of wings and different beam angles. This allowed lighting engineers to select lanterns for specific sections of road, especially for bends, dead-ends and road junctions.

In this era before any standardization and/or conformity of mounting heights and spacing, the original Bi-Multi was a small lantern, designed to cast a narrow, intense beam as directed by each wing. This allowed roads to be lit under varying conditions with a minimal number of lanterns; but the intensity ratio was excessively high and glare was a constant problem.

The first British Standard (BS 307:1927) did nothing to improve matters; but the coming of the MOT Report (1937) finally standardized mounting heights and spacing, and Harrison was able to change the optical system of the Bi-Multi to reduce the intensity ratio and create a wider beam. The result was the larger Bi-Multi Group "AL" (with the original Bi-Multi system becoming the Group "A").

As bulb wattages increased, a Group "B" lantern was introduced to light Group "A" roads (suggesting that Harrison's lantern predated the standard naming of the MOT Report). Twin lamp version also appeared, but were only used for special circumstances.


Being rugged, simple and cheap, the Bi-Multi system was extremely popular, and these characteristic facetted lanterns could be found all over the country. They were especially popular both with the suburban expansions of the cities being built in the 1930s, and various Parish Councils who needed a cheap, effective, and above all, simple lantern.

Their popularity waned in the 1950s with the coming of discharge lamps and enclosed lanterns, and the energy crisis of the 1970s saw large numbers being removed. Whilst only a handful on exist on the public highway, they have become highly sought after by enthusiasts, and the Bi-Multi has become a collector's item.


The ESLA Bi-Multi is easily identified by its glass facets. If a lantern has three rows of mirrored glass facets then it's an ESLA. Further identification is provided by the makers name, angular schedule, and patent numbers on the canopy of the lantern. In early lanterns, this is scribed into the wings (requiring paint removal to see them); on later lanterns, these are cast as raised letters (rare) or raised letters on blocks.

Optical System

The optical system of the ESLA Bi-Multi was based on a series of intersecting parabolas with the bulb at the focal centre. The top half of the parabola was fashioned into a reflective surface using facetted mirrors. The flux collected by the mirrors was then fashioned into a beam, the elevation, angle and number of beams corresponding to the geometry of each wing.

Early Group "A" lanterns varied the peak angle (with the angle scribed on the lantern's canopy) whilst Group "AL" lanterns fixed the peak angle at 80°.

Flux emitted from the lower hemisphere of the bulb was uncontrolled, and formed a circular pool of light beneath the lantern. Therefore, the area around the base of the lantern was well illuminated for the pedestrian and house owner (e.g. pavement, front gardens and parked cars) and the road surface was illuminated at longer distances from the lantern for the car driver (e.g. bright road surface, dark kerb edges etc.).

Focusing was variable: the bulb assembly could be adjusted in a vertical axis by moving the tubular bulb holder within the lantern's canopy; a simple locking screw held it in place. The bulb's filament was positioned at the lowest point of the wings for correct focusing, a relatively easy task.

the esla bi-multi group "a" two-way 165° 7½° in my collection

facing profile

This lantern (and associated bracket) was purchased from a house in Wimbledon, South London. The owner was remodelling the house and garden and didn't want the street light. So, the builders rescued it and offered it to me.

front profile

The glass was in good condition and the lampholder was complete. Apart from rewiring, stripping all the paint off and repainting it, the lantern didn't require much other attention.

The etched identification lettering can just be seen on the canopy of the lanterns. Normally this writing is hidden under layers of paint.

trailing profile

The lantern came into the collection painted blue with a green undercoat. Neither were original to the Municipal Borough of Wimbledon so it was restored to its original white colour.


During repainting, the etched letters identifying the lantern's angular schedule were revealed. These read:
165o 7½°
No 736776 ESLA

British Pat No 228294/23 Road -->

The second figure is believed to be the peak angle below the horizontal which was variable for these Group "A" lanterns. (In the later Group "AL" lantern, it was fixed to 10°).

pedestrian view

The lantern has been fitted with a Derby 100 bulb, the original specification for this lantern (which shows how small this lantern is when compared to its larger Group "AL" siblings).


The lantern has the familar ESLA configuration of three rows with ten columns. None of the centre glass has survived.

It was retained on its original Lucy bracket.

the esla bi-multi group "a" two-way 165° 7½° as aquired

I collected this lantern and bracket from Wimbledon in late 2019. It had been used as garden lighting and was fitted with a darkened and broken CFL lamp.

This type of swan-neck and lantern was very popular in Wimbledon where they were installed by the Municipal Borough of Wimbledon in large numbers during the 1930s. I suspect this example was rescued by the house owner when the street was relit and planted in their back garden.

It was painted blue with a dark green undercoat. Neither colour was original and so all this paint was removed.