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ilp archive : journals

public lighting no. 50 vol. 13
April-June 1948


Editorial p59
Hubert Offen Davies p59
Replies to APLE's Secretary Hubert Offen Davies obituary.
Lighting: Personnel


Eastbourne Conference p59
Already there are early indications that the APLE Conference to be held in Eastbourne will prove a great attraction. The indoor Exhibition of Street Lighting apparatus and equipment is being staged in the same building as the Conference Hall. The APLE with the co-operation of the Eastbourne Authorities have permission to use an aread of ground immediately adjointing the Conference Hall where lamp columns will be erected.
APLE: Conference


Exhibition p59
Details of the exhibition opening times, hotels, social functions (including tours and teas) and particular details For The Ladies.
APLE: Conference


Eastbourne p60
Description of Eastbourne.
APLE: Conference


Exhibition of Street Lighting Apparataus and Equipment p60
Details of the indoor exhibition of Street Lighting apparatus, the display of lamp columns, and a list of manufacturers participating.
APLE: Conference


The Institution of Gas Engineers - 85th Annual General Meeting p62
The Right Hon. H. T. N. Gaitskell, C.B.E., M.P., Minister of Fuel and Power had been working on the framework within which the industry should be re-organised. A full report of the Minister's speech was recorded. Following the report of the Heyworth Committee the Industry is being transferred to public ownership with the management in the hands of Area Boards. The Gas Council will consist of the Chairman and Deputy Chairman, independently appointed by the Minister, and consisting of the Chairmen of the Area Boards. The UK is to be split up into twelve Area Boards (two more than advised by the Heyworth Committee).
Other


Rythmatic Control System - St. Anne's p64
Details of the Rythmatic Control System installed in Lytham St. Anne's.
Lighting: Control


Sir Clifford Paterson p65
Sir. Clifford Paterson, director of the GEC Research Laboratories, is to be awarded the Gold Medal granted annually by the American I.E.S. for meritorious achievement.
Lighting: Personnel


Scottish Section p65
The Scottish Section has now been formed. The idea originated at Southport, where the Scottish Members and Delegates held a meeting, and their keenness and enthusiasm has resulted in further meetings in Scotland. This Section has received hte blessing of the parent body. At a meeting held in Glasgow on May 28th 1948, under the Chairmanship of Thos. Wilkie, F.I.E.S., the members of office were elected. T. M. Lappin, Public Lighting Engineer of Dundee was elected Chairman.
APLE: Organisation


Lancashire Section p65
The Lancashire Section has now been formed. At a meeting in Liverpool on April 26th, 1948, C. C. Smith of Liverpool was elected Chairman. The main object of the Lancashire Section is to provide opportunity for discussion and interchange of information,by correspondence or by meetings. A tour was made of Liverpool which included sodium, blended sodium, fluorecent and tungsten lighting. The tungsten lighting was unique as they were mounted at 40 feet with 34 yard spacing and 500W lamps - this gave a very even illumination with a very low diversity factor.
APLE: Organisation, Lighting: Installations


The Use of the Burman Prism in Street Lighting (A Better Light for No More Fuel) p66
Invented by Mr. J. H. Burman, who has applied the optical properties of a smooth triangular prism to street lighting units.

Theoretical Considerations
In the case of a triangular prism, a light ray falling upon one face of the prism, so that the angle between the light ray and the prism face is small, is refracted upon entering the prism, and again upon reaching the second face. These properties of simple reflection and refraction are utilised in the principle of Burman's Smooth Prism Principle. As the angle between the light ray and the prism face is increased the angle the angle between the emergent ray and the second face of hte prism becomes more and more acute until a point is reached at which the emergent ray actually coincides with the second face of the prism. The angle which the light ray passing through the prism then makes with the normal to the second face of the prism is termed the critical angle, and this angle depends upon the character of the medium i.e. upon its refractive index. At still wider angles between the incident ray and the face of the prism, the light is reflected back from the second face of the prism, to emerge from the third side. This is termed total internal reflection, and is also made use of in the Burman application. Finally, when the light ray is perpendicular to one face of the prism, and in the case of 60-degrees prism, will meet the third face perpendicularly, after being totally refelcted from the second face, to emerge without refraction.

Calculation of the Parth of a Light Ray Through a Prism
The path of a light ray through a prism can be easily calculated bearing in mind the facts that the angle of reflection is equal to the angle of incidence and refraction is constant and equal to the refractive index of the material of the prism.

Practical Application
Three triangular prisms are arranged around the light source, which may take the form of an alignment incandescent mantle burner. It has been found that prisms with angles of 62°, 59° and 59° give satisfactory redirective effects. The lower prism is positioned immediately beneath the light source at a distance of one inch from the base of the incandescent mantles, so that a horizontal face is presented to the light source. Light which would otherwise be directed upon the ground in the immediate vicinity of the lamp column, is thereby redirected at angles of from 75° to 80° from the vertical, mkaing use of total internal reflection. The upper prisms are arranged at teh sides of the light source so that the 62° angle is nearest to the source at a distance of 1 7/8 inch, and with the bottom face slightly drooping as it recedes from the light source. These prisms are utilised to redirect upper hemispherical light (i.e. light which would otherwise be wasted above the horizontal) at angles between 75° and 80° from the vertical, making use of the properties of simple reflection and refraction. Two lengths of prism are at present used: 5½ inch for the upper prisms and for the lower prism with 4-light and 3-light alignment burners; and 2¾ inch for the lower prism in the case of some 2-light burners. The length of the prisms is responsible for a wide beam extending over 40° between 75° and 80° from the vertical.

Effect of the Prisms on Beam Candle Power
The candle-power at 80° with the source is 200. This is increased to 345 with the lower prism, and to 365 with the upper prisms. With the combination of lower and upper prisms the candle-power is increased to 510, equivalent to an increase of 155%.

Effect of the Prisms on the Distribution of Illumination
The figures emphasise the superiority of the 2-light No. 1 mantles burner with combined prisms over the 4-light No. 2 mantles burner without. The prisms are easily removed for cleaning and replaced in their correct positions. The smooth glass surfaces are non-corrodible and free from crevices for the collection of dust. The upper prisms may also be adjusted to allow for gradients.
Lighting: Distribution, Lighting: Levels, Lighting: Maintenance, Lighting: Theory


Increased Street Lighting p69
The Minister of Transport has announced to the House that there would be some relaxation in the restrictions of Street Lighting. Communications have now been despatched by the Ministry to County Councils, County Borough Councils, The Common Council of the City of London, Metropolitan Borough Councils, Town Councils, Urban District Councils, Rural District Councils in England and Wales, County Councils and Town Councils in Scotland. Extracts are:
"Lighting Authorities are asked to make their plans for the next twelve months on the basis of a minimum saving of 25% on pre-war lighting consumption. If, however, a Lighting Authority considers that it cannot achieve the minimum saving of 25%, it should get in touch with the Divisional Road Engineer, who if satisfied after consultation with the Regional Fuel Officer of the Ministry of Fuel and Power, may agree upon a lower figure."
"Lighting should be provided: (a) at street and road junctions where there's a heavy volume of pedestrian traffic after dark; (b) for bollards, obstructions, traffic signals and important illuminated traffic signs; (c) in streets where lighting is required to enable essential work to continue at night; (d) at named points where the Police advise that street lighting is essential."
"Lighting Authorities are asked to make their plans on the general basis that main traffic routes in built-up areas will be lighted to a good standard, the necessary economy being effected by a saving in the lighting of other roads."
"Before a Lighting Authority reaches a final conclusion as to the roads on which the saving in lighting is to be made, its proposals should be agreed with the Chief Officer of Police concerned. Unless the Police recommend to the contrary, all street lighting should be extingushed at midnight. It may be brought into operation again in the early hours of the morning where this is thought to be necessary and is technically possible."
"The continuing need to curtail investment expenditure, so as to reduce demands on materials and labour which are scarce, means that only in certain cases (below) will it be possible to approve the installation of new or improved lighting systems. The Minister will be prepared, to consider, for authorisation under the powers of Regulation 56A of the Defence (General) Regulations 1939, new or improved street lighting which: (a) is essential for the safety of traffic; (b) is required by the Police for the efficient performance of their duties; (c) is necessary for side roads, such as roads serving new housing estates."
This was circulated as Circular No. 621.
Lighting: ARP, Lighting: Energy, Lighting: Legal, Lighting: Users


Fluorescent Street Lighting In Buenos-Aires p69
New fluorescent street lighting was installed in Calle Florida, Buenos-Aires. The equipment was supplied by BTH. 15 BTH fluorescent street lighting lanterns, each accommodating three 80-watt 5-ft. "warm-white" fluorescent lamps have been suspended on twin catenary wires 25 ft. above the centre of hte roadway at intervals of 80 ft.
Lighting: Installations


A Century Of Public Health p69
Details about the forthcoming Public Health and Municipal Engineering Congress and Exhibition to be held at Olympia, London from November 15th to 20th.
Other


Street Lighting Fitting For Combination Tungsten/Sodium Vapour Discharge Lamps p70
There are many thoroughfares where some degree of colour discrimination is desirable notably promenades, civic centres or shopping areas, and it was to meet this requirement that the REVO C12122 lantern was primarily designed. The lantern comprised a combination of two standard tungsten filament lamps with a sodium lamp and satisfactory colour rendering is obtained for normal purposes. The addition of the tungsten lamps greatly enhances the general appearance of an installation and enables an exceptionally attractive and cheerful form of street-lighting to be provided at a low running cost. Effective distribution of light is obtained by means of the special arrangement of reflectors and refractors and the lanterns comply with the MOT Final Report 1937. Cast alumininium alloy one-piece canopy with substantial frame carrying patented refractor panels, the upper sections of which are clear to allow efficient transmission of reflected light; the lower portions having a prismatic formation to control the light emitted from the sodium lamp. Clear glass panels are provided for the prisms to facilitate cleaning, but may be omitted when desired. The internal reflectors are of high quality silvered glass. The tungsten lamps are accommodated in the ends of the lantern which are glazed with opalescent diffusing panels. A wiring chamber is incorporated and the lampholders are wired on separate circuits for the sodium and tungsten lamps. The lantern is supported from a cast iron dome on which it may hinge and from which it is readily detachable. Wiring from the terminal block to the lampholders is provided.
Lighting: Luminaires


Borough of Sale - Street Lighting Scheme p70
Details of the new installation in the Borough of Sale.
Lighting: Installations


GEC to Relight Romsey p71
Details of the new installation in Romsey.
Lighting: Installations


Tower Wagon with a "New Look" p71
Description of a tower wagon by Eagle.
Lighting: Equipment


First Time Ever! p72
The BBC recently broadcast First Time Ever! from Godalming. Written by Leslie Bailey it covered many subjects including dramatised scenes showing how the new electric light came to Godalming. In 1881 John Pullman, who owned a leather mill on the banks of the river Wey, offered to place his water-power machinery at the disposal of the Borough every night and run a cable from the Mill to the High Street. (He hated waste and proposed using the power from his dynamo at night to light the streets). Three electric street lamps were installed including one outside the Town Hall. Part of the script was then reproduced.
The Graphic magazine reported the event: "The effect of the quaint old High Street with its gabled houses lit by electric light is so strangely theatrical. At present, only three lamps are affixed upon poles twenty-four feet high. It is in contemplation to increase the lighting by about twenty smaller lamps. Although this will be an improvement, yet the picturesque constrast of light and shadow will, of course, cease to exist."
Lighting: History


The Use of Street Fixtures as Reflectors by D. G. Sandeman, B.Sc., A.M.I.E.E., Head of Engineering Dept. East Ham Technical College p73
A correct approach to the problem of street lighting should be from the point of view of the man in the street and not of the laboratory.

The Assessment of Public Lighting
The simple question "How good is a certain installation?" has not yet been answered with scientific precision. The problem of measuring street lighting is very difficult. How desirable would it be if we could make all our roads at night into tunnels with bright walls and roof.

Luminous Arches
Let us imagine we erect arches every 100 feet along the roadway, each arch luminous and one foot in diameter. The near wall would show eleven bars of light and at the twelfth the bars would touch and form one patch of light - the proportion of bright background would be 2¼%. Taking the roof, there would be nineteen bright bars and at the 20th they would touch and form one bright line - 3½% would be bright. Thirty-seven bright bars would be distinguishable on the right-hand wall and at the thirty-eigth the bright line would begin, giving 6¼% for brightness. The average figure for the three sectors is 4¼% - this looks small but represents a bright patch directly ahead and tailing off in bright bars farther and farther apart as they get out of line.

Practical Considerations
There are two methods of attempting the luminous arches. The first is to form triumphal arches of strip lighting from pavement to pavement - a very modified for of the ideal only is available at the moment. Bare lamps would be used and instead of cleaning there would be replacement. Luminous efficiency should be a secondary consideration. We know so little about street lighting that the mistake has been made in the past of measuring the two quantities which lend themselves most easily to measurement, foot candles and lumens. It is like measuring beauty by weight or worth by wages. A more practical method which makes bright vertical portions and only two fragmetns of the roof, consists of using the lamp columns themselves to reflect light.

Conclusion
Lighting by luminous arches processes the following unique advantages: (1) It is capable of precise specification by a percentage of bright background; (2) The road surfafce is more evenly illuminated; and (3) The method embodies all the best features of existing and well-known methods of street lighting and encourages improvements by correct assessment.
Lighting: Theory


Correspondence p74
Corrrections of discussion points by J. G. Christopher on Steele's paper on Side Street Lighting. ("The lower limit for traffic routes - 3000 luemns per 100 ft. with 25 ft. columns - is nowadays recognised to be scarcely adequate, and any lower standard consequent upon the introduction of a third standard might not be sufficient to enable traffic to proceed in safety without the use of headlights.")
APLE: Journal


British Electricity Authority Vesting Day p74
Reminder for members to forward to the Secretary's Office any alteration in title and address.
APLE: Organisation


Adverts: Poles Ltd, Londex Ltd, Stanton Ironworks Co., Ltd, Siemens Electric Lamps And Supplies Ltd., British Gas Council, Broads Manufacturing Co. Ltd., Automatic Telephone And Electrical Co., Ltd., Holophane Ltd., Stewarts And Lloyds Co., Ltd., REVO Electric Co., Ltd., British Electrical Development Association, Inc, The British Thomson-Houston Co. Ltd., James Keith And Blackman Co., Ltd., Concrete Utilities Co., Ltd., Parkinson & Cowan (Gas Meters) Ltd., Willey And Co. Ltd., Engineering And Lighting Equipment Co. Ltd., Gowshall Ltd., Hobbs, Offen & Co., Ltd., The Horstmann Gear Co., Ltd., Walter Slingsby and Co., Ltd., British, Foreign And Colonial Automatic Light Controlling Co., Ltd., Falk, Stadelmann Co., Ltd., William Sugg And Co., Ltd., Metropolitan Vickers Electrical Co. Ltd, Sangamo Weston Ltd. and The General Electric Co., Ltd.