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ilp archive : journals

public lighting no. 5 vol. 2
March 1937


Editorial p3
Coronation Illumination Devices: These will be on a scale exceeding those of the Jubilee Celebrations of 1935, floodlighting being considered the simplest and most effective and many manufactures have made immense ranges of illuminating devices including ornamental street lighting; Black Out Grievance: a complaint about part-night lighting "as a ratepayer he bears his share of the lighting rate, and naturally feels aggrieved that this particular amenity should be denied him in the small hours, while his more fortunate friends in the same neighbourshood who live nearer to, or adjoining, a road which is much used for traffic daily, suffer no such depreivation. The correspondent makes the very reasonable point that, while there may be some financial justification for this action, yet there remains the question of the householders' protection from nocturnal marauders, whos nefarious practices are likely to become more active in those roads in whcih a "black-out" exists after midnight." A possible solution is by the extinguishment of alternative street lamps, or by minimum lighting generally; Air Raid Precautions: This should be the sole responsibiltiy of the Public Lighting Engineer [although it's interesting to note that "much activity is being displayed by local authorities" at this early date]; Street Lighting Progress: 36,000 discharge lamps are now used in the UK which is greater than in all the leading countries abroad put together. In London alone, over 300 miles of streets are so lighted while over 200 local authorities are employing this "accident-proof" type of lighting.
Lighting: Events, Lighting: Levels,


New Lamp Development p4
The GEC have introduced their new high pressure mercury lamp (later MB) at the British Industries Fair. Rated at 80 and 125W, this new "Osira" mercury electric discharge lamp has an extremely high efficiency and gives three times as great light output as a tungsten lamp of equivalent wattage. It is similar in shape to the ordinary tungsten electric lamp and is internally frosted. To avoid confusion with the tungsten type of lamp it is fitted with a three-pin cap.
Lighting: Lamps


Lighting Authorities Can Help Road Safety p4
"I am sure that if we are to reduce this appalling loss of life on the roads, the loss which, in any one year, is greater than the whole of the loss of life in the two years eight months of the South African War, it will have to be through the co-operation of manufacturers, suppliers, and public lighting authorities." - Alderman J. Chuter Ede, M.P. for South Shields.
Lighting: Social Comment


Bottled Gas p4
Among the proposed illuminations at Coronation time at Wallasey are to be displays in which compressed gas will be used. This is being increasing used owing to the enterprise of the Corporation's Gas Department.
Lighting: Events


Coronation Displays p4
Details of gas floodlighting schemes of various buildings including Gas Industry House (on the direct Coronation Route), St. James's Park (where 300 concealed gas projectors will be used) and Devonport Park, Plymouth; other displays are planned at Edinburgh, Stoke, Guernsey and other towns.
Lighting: Events, Lighting: Floodlighting


Road Lighting: Counties And Road Fund Grant p4
In the report of the Executive Council to the County Councils' Association on the 23rd March, reference is made to the efforts of the Council, so far without success, to obtain a Road Fund grant in aid of such road lighting as may be undertaken by County Councils. The view of the Minister of Transport is that he does not possess any power to comply with the request.
Lighting: Funding


New Street Lighting In Fulham (London, S.W.) by W. C. Parker Borough Electrical Engineer p5-6
Full details of the Fulham main road installation.
Lighting: Installations


Bicycle Allowance For Lamplighters The Times January 5th p6
"Palmerston, when Queen Victoria once rebuked him for being late, made bold to reply that he could not run like a lampligher." This quote is still being made today, but only rarely and usually by elderly people. It belonged to a past age when lamplighters really did run but has little application to now when lamplighters ride bicycles. The lamplighers of Southampton have taken issue with their employers over the allowance that should be paided for using their own bicycles and performed a "go slow" by walking their rounds at the weekend. The lampligher's bicycle allowance has been a local agreement between employer and lamplighter and has not caused any problems in the past.
Lighting: Equipment


Bristol's Improved Street Lighting To Cost 120,000 p6
Details of a proposed improvements to Bristol's lighting.
Lighting: Installations


Illumination Measurements p7
During the last few years, methods of illumination measurement have been revolutionised. The human eye might be said to have been designed as a seeing device but it could never be classified as a measuring device. Until recently, practically all methods of illumination measurement consisted of comparing a surface of known illumination with another surface whose illumination was unknown - this comparison depended upon the human eye. With the advent of the "Barrier" type photoelectic cell this whole situation has changed. This develops sufficient current in even moderate light intensities to operate a milliameter without the use of external batteries or amplifying devices. When comparisons are to be made between illumination of different colours, then the colour sensitivity of the cell becomes important and the best procedure is to employ a colour filter in conjunction with the cell, which eliminates the invisible radiation and reduces the balance of the radiation to a proportion so that the total response of the cell is equivalent to that of the human eye. Indoor illumination is prodvided for two reasons: for seeing and for beauty. Measurements are them considered:

0-3 foot candles Inadequate
3-10 foot candles Suitable for stairs, hallways, warehouses and auditoriums
10-20 foot candles Suitable for retail stores, school class-rooms, general offices and factories producing rough products
20-30 foot candles Suitable for drawing and sewing rooms, factories making average products and offices doing close work.
30-50 foot candles Suitable for factories producing bulk products and for inspection departments examining carefully fine articles

Outdoor artificial illumination is provided for safety and convenience as in the case of roads and airports; to prevent theft or sabotage as in the case of works; and for advertising as in the case of floodlighting. [Note: "beauty" is not considered in this context.]

There is some controversy as to the correct method of illumination especially of roads. While some people are in favour of the measurement of contrasts, shadows etc., it is still generally agreed that average illumination in terms of foot candles is what is more desirable. In making such measurements, due thought must be given to the angle of incidence of the light upon any given surface and the colour of the light source.

(Two units are pictured and described. Includes Spectral Response Curves for the eye and the cell.)
Lighting: Equipment


Better Gas-Lighted Streets p8
Yearly statistics published by the gas industry show that many lighting authorities in our large towns and cities continue to rely on gas lighting. Of the fourteen districts named, there have been an increase of 10,000 lamps from 1935.
Lighting: Installations


Some Aspects Of The Street Lighting Problem by S. English, D.Sc., F.I.C., F.Inst.P. Holophane Research Laboratory p9
Excerpts from a Paper read at a meeting of the Illuminating Engineering Society, held at the Institution Of Mechanical Engineers, London, on the 9th March 1937.

[A very interesting paper which is one of the first published criticisms against the new road surface brightness theory. The full paper should be found as these were just notes made at the meeting.]

Uniform Illumination
1. Recalled the early work by A. P. Trotter and stated "the avowed aim of the early workers in this field was to produce a near as was commercially possible uniform illumination along the roadway, a diversity factor of less than 10 to 1 being regarded as reasonably good, while with non-directing equipment and the relatively wide spacing then adopted the diversity ratio of reached 40 to 1."
2. In the days before tarmacadam roads, this aim was excellent, as the road surfaces were much lighter in colour and had much more difusely reflecting surfaces than modern roads e.g. rough concrete, granite sets.
3. Pedestrian could use direct vision and motorist could use silhouette vision to see near and far objects respectively.
4. These early workers also realised that directional lighting needed care, since the indiscriminate projection of intense beams of light along a road was liable to give rise to uncomfortable glare unless the angle of elevation of the beam was carefully controlled. In well designed directional fittings, the main beam was generally projected at 15° below the horizontal.
5. The adoption of this angle allowed space-height ratios up to 8. Attempts to reduce the cost of the installation and maintenance, by increasing the space-height ratio, either by increasing the spacing or decreasing the mounting height, involved the use of higher beam angles, with a consequent increase in glare.

Road Surface Brightness
1. The widespread use of tarmacadam and asphalt, which take a failry good polish after being subjected to heavy motor traffic, has led to the resurrection of theories of street lighting based on road surface brightness.
2. During recent years the important of high and even road surface brightness has been emphasised in this country and in some quarters almost elevated to a creed, apparantly being regarded as the one and only characteristic of a street lighting installation worth of attention. For instance, the question of glare appears to be completely ignored, thought it is obvious that strong beams of light impinging on the eye only a few degress from the normal line of sight must result in an impairment of vision.
3. The statement is made that a polar curve of a particular type is necessary to produce high and uniform road surface brightness:
  • No body of evidence to support such a statement has been published.
  • It is generally agreed that the brightness of the road surface is more a function of the nature of the surface than of the precise form of the polar curve.
  • Brightness distribution on a road surface can be completely altered by a simple repair or even a shower of rain.
4. In towns and popular areas where pedestrian traffic is heavy and where the road surface only forms a relatively small proportion of the background, it seems obvious that different form of lighting could be adopted. For heavy pedestrian traffic uniformity of illumination is of greater importance, for the motorist it is road surface brightness.

Real Aim Of Street Lighting
"The aim of street lighting is not to produce uniform illumination along the roadway, nor to produce uniform and high surface brightness, nor to eliminate glare, nor to produce a constant degree of glare, but to simply to enable road users of whaterver class they belong to see clearly whatever they need to see, more particularly to see obstacles and circumstances that may lead to danager." It does seem neccessary to say this in order to bring some specialists down to earth and to get them to realise that there is something in the points of view that are held by other people regarding the means by which good street ligthing may be achieved.
The pedestrian needs to see people and things generally at a relatively close range.
The motorist needs to see clearly and quickly in the near neighbourhood of his car as well as objects on the road a quarter of a mile away.

Experimental Work
"If an attempt is made to determine in an experimental manner what constitutes good street lighting, innumerable difficulties crop up:"
  • Psychological - what is good street lighting is a matter of opinion and it is difficult to get agreement. Even if agreement is obtained, it is still more difficult to get a numerical evaluation of the goodness of an installation.
  • Physical - the enormous number of variables e.g. mounting height, space of units, lumen output, type of light source, light distribution of fittings, cut off, nature of road surface and its condition.
Lighting: History, Lighting: Distribution, Lighting: Theory


Representation Of Street Lantern Characteristics by R. Maxted, B.E.Elec., B.E.Mech. p10
Excerpts from a Paper read at a meeting of the Illuminating Engineering Society, held at the Institution Of Mechanical Engineers, London, on the 9th March 1937.

Suitable diagrams for representing lantern characteristcs must by used to (1) investigate the fundamental factors influencing visibility and (2) allow the specification of a street lighting installation. "In street lighting, the goal can only be approximately defined as visibility; and the degree of visibility necessary, or the extent to which it has been achieved, is entirely a matter of the experience and judgement of all classes of road user."

Objective Factors To Be Analysed
Installation design must be examined from two points of view: (1) Providing suitable brightness of backgrounds and objects and (2) Avoiding or limiting the neautralising effects of glare. Unfortunately it is light which has been projected towards the observer for the purpose of producing surface brightness whcih may also give rise to glare."If it is proposed to modify a lantern distribution with a view to reducing glare, then the surface brightness must also be changed, and an optimum lantern design can be obtained only by a compromise between the requirements for surface brightness and glare."

Glare And Cut-Off
Glare cannot be described satisfactorily in terms of brightness, for whilst an excessive source brightness may result in discomfort glare, disability glare is a function of the intensity and the angle of light projected towards the eye. Similarly repetitive glare effects arise mainly from variation in these factors produced by movement of the observer.

The Specification Of An Installation
"In an analytical survey of street lighting, the records should cover the lantern characteristics, the distribution of brightness, and the location of units." A complete account of the lantern distribution is given by the iso-candle diagram. It seems advisable to seek a specification based entirely upon the installation layouts and the lantern characteristics. "Thus the lantern distribution would be determined by the minimum size of the bright patch to be produced by an individual lantern when the road surface is in the least favourable conditions. The installation layout would then place the lanterns so that the bright areas coalesced to give satisfactory overall surface brightness from the normal path of the observer."

Lumen Basis Of Lantern Curves
While the 400W HPMV lamp gives an initial output of 18,000 lumens, the curves of lantern performance should be based upon a perfectly clean lantern and a lamp output of 12,000 lumens. With the lamp giving an average of 16,000 lumens over life, this allows a factor of safety of 33% to cover all other contingencies such as variations in road surface, reflectivity, efficiency of cleaning, accuracy of lantern erection etc.

Conclusion
Sources of different colour should not be mixed indiscriminately in a survey aimed at the study of lantern distributions.
Lighting: Theory


Modern Gas Street Lighting Installations by W. J. G. Davey, B.Sc. and A. R. McGibbon, A.M.I.E.E.
p11-16, p21-28
Enitre copy of the paper given at the conference. Originally contributed for the Lighting Section of the Society of British Gas Industries.
Lighting: Luminaires, Lighting: Specifications, Lighting: Theory, Lighting: Installations


Folkestone p20
Arrangements for the forthcoming conference in Folkestone. Also includes new members, junior members and associates.
APLE: Conference, APLE: Organisation


Night Photography p20
Recommendation for Messrs. Hobbs, Offen & Co., who carry out night photography of installations for manufacturers.
Lighting: Photography


Coronation Floodlighting p29-30
Descriptions of various electrical schemes planned for the Coronation. "Electricity is rapidly progressing, largely owning to the improvements in generating plant and efficiency in working, and a consequent reduction in operating costs." Discussion of the plans of various authorities of the floodlighting of public buildings, memorials, institutions etc. BEDA have sent out a circular stressing the potential advantages of electricity generally. The article notes how many temporary floodlighting schemes are becoming permanent. Includes plans of several local authorities.
Lighting: Events, Lighting: Floodlighting


Newcastle Coronation Street Decoration Lighting p30
Newcastle Corporation will installed 132 large decorative lanterns for the coronation. The lantern, which is of rectangular shape, is by the GEC It is 4' high and 28" wide.
Lighting: Events, Lighting: Floodlighting


Park Illumination by a London Parks Superintendent p30
Suggestions for the increased use of parks in the winter months. This includes lighting: "So far, with some exceptions, the attempts at artistic park and garden illumination have been of a crude order, accompanied by a considerabl amount of paraphernalia and various contraptions, which, in the day time at any rate, are often in the way, highly dangerous and far from being beautiful... It is sincerely to be hoped, however, that we shall be spared in such lighting systems the ghastly effects which are produced by mercury vapour lamps in the countenances of otherwise pleasant looking individuals."
Lighting: Social Comment


Street Lighting In Romford: Competitive Supply by F. V. Appleby, M.Sc., A.M.Inst.C.E., M.Inst.M. & Cy.E p31-p33
Eastern District of the Institution of Municipal and County Engineers, Romford, March 11th, 1937
Description of the requirements of the new installation. Includes the The Urban District Council's Specification for street lighting. (See "Romford" section in the link.)
Lighting: Installations


Lighting News From Members p34
Details of various installations sent in by members of the association.
Lighting: Installations


Obituary p34
Obituary of Charles F. Blincoe, the Gas Manager and Public Lighting Superindendent for Middlesbrough.
Lighting: Personnel


Street Lighting News p35
Brief details of various installations.
Lighting: Installations


Adverts: Philips Lamps Ltd., William Sugg And Co., Ltd., Walter Slingsby and Co., Ltd., South Metropolitan Gas Co., The British Thomson-Houston Co. Ltd., Radiovisor Parent Ltd., Siemens Electric Lamps And Supplies Ltd., British Commercial Gas Association, Gowshall Ltd., Foster And Pullen Ltd., Concrete Utilities Co., Ltd., The Horstmann Gear Co., Ltd., British Electrical Development Association, Inc, Gas Meter Company, Public Works Roads & Transport Exhition And Congress, W. Parkinson and Co., Bromford Tube Co., Ltd., James Keith And Blackman Co., Ltd. and The General Electric Co., Ltd.