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ESLA Bi-Multi Group "AL" Two-Way 165°

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 "AL" Two-way 165°
Date: Circa 1920s - 1950s
Dimensions: Length: 12 ¼", Width: 11 ¼", Height: 10 ½"
Light Distibution: Non Cut-Off Distribution (MOT Report 1937)
Lamp: 40-200W GLS




History

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.




Popularity

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.




Identification

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 n 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.




facing profile

Silver painted ESLA Bi-Multi Group "AL" lanterns used to light the suburban lanes of Sutton, Surrey. Fitted to huge Lucy brackets, mounted on fluted and/or octagonal cast iron columns, these street lanterns were probably the original street light installation, as the sprawl of Greater London swallowed Sutton, Cheam and the other outlying villages. As my grandparents lived in Sutton, I became familiar with these installations, and so my fascination with these mirrored lanterns was born.

A huge relighting scheme in the 1970s started to sweep these old lanterns away. Gradually all the lanterns from Sutton were removed, but the scheme stopped short by the Sutton Bypass. After a reprieve of ten years, the replacement started again in the late 1980s, and the remaining ESLAs were removed and consigned to the council tip (or so I thought).

In the early 1990s, I travelled to Cheam Village to pick up an antique computer game system. As I drove into the village centre, I happened to glance down “Park Road” and to my amazement, realized the road was still lit with these old lanterns. This ESLA and swan neck were the first I saw that day; and my girlfriend indulged me as I drove randomly around the backstreets to discover a large remaining installation.




front profile

The installation around Cheam Village was the last remaining bastion of the huge installation I remembered from my youth. Sutton Council were willing to help me, as they’d offered many brackets and columns to local residents who wanted to save their old lights. And the lanterns from Cheam Village were being removed, so it was with these remaining lanterns and brackets that my collection really started to grow.

As I walked around, I finally fully appreciated the number of variations of ESLA Bi-Multi lanterns. Park Lane, a short road, had at least four different designs of 2-way and 3-way lanterns installed along its length. Mr. Gorey, the lighting engineer at the time, confirmed my suspicions, mentioning that even the 2-ways were slightly different. But as the Sutton ESLAs were an early installation, I wouldn’t discover that I’d accidentally picked up several different 2-way types until I’d learnt the trick of scraping the paint of the canopies to reveal the angular designations.




trailing profile

I got my hands on this Park Lane lantern in 1996. It was the first I saw that day, and I could positively identify it by its uncharacteristic BLEECO time-switch box. The lantern was in good condition, with the mirrors complete, although some of the silvering was becoming oxidized through age. Scrapping of the paint revealed it to be the common 165° variant; which was to be expected as it lit a straight section of road.




canopy

The maker, patent, angle and mounting instructions were scribed into the lantern’s canopy and couldn’t be seen until the original paint was removed. They can just be seen through the new paint above:

BRITISH PAT No 228294/25

ESLA REG No 73677 165°

A 2-way 165° lantern was the most popular Group "AL" produced. It was used to light straight sections of standard width road in a staggered formation.




pedestrian view

This ESLA was one of my earlist acquisitions and I simply stripped it and repainted it. It quickly went rusty. So I stripped it again, used rust inhibitor, added two coats of red-oxide and then repainted it. Of course, it had to be painted silver, the colours favoured by Sutton Council.




vertical

After decades of service, this shot shows just how superb the mirrors are on this ESLA, although the mirroring has failed in places. Note the usual configuration of 3 columns and 10 rows of facets.

I'm extremely pleased that I discovered this installation, and was able to save a small number of brackets and lanterns. I was doubly pleased as Cheam Village is a conservation area, and these lanterns and brackets were part of the original 1930s installation – so a small piece of the UK’s history has been saved. However, it is sad that conversation area stipulations don’t extent to the original street lighting – Cheam Village, an prime example of the expansion of 1930s London, is now lit with mock-Victorian gas lamps. Although I’m probably the only person who’d notice.

The lantern has been kept on its original Lucy large swan neck bracket.







ESLA Bi-Multi Group "AL" Two Way 165°: As Originally Purchased

An ever popular, and ever collectable, ESLA. The bulbholder has become unsoldered from the anti-vibration spring, which I've yet to fix, hence the tape holding it in place.

It's been painted silver, the colours used by Sutton Council as the lantern originally stood in Cheam.