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ilp archive : journals

public lighting no. 20 vol. 6
January 1941


Editorial p5
The second winter of "black-out" is passing. Lessions in war-time street lighting has been learned - mistakes have been remedied. It is gratifying that modified stret lighting, as specified by BS/ARP 37, has given great satisfaction to those whose duties require use of the streets after dark, but has proved of infinite value to those who, during nightly raids, have ebeen able to carry out their dangerous duties more efficiently, by the degree of "safety lighting" permitted. Few towns are now without an installation. But there are certain key towns in the countries where blackness and gloom reigns after dark. It has been stated and restated that these fittings give a reasonable amount of light for the road user and pedestrian and is quite invisible from the air. It is also disappointing to learn that in a few isolated cases, the new lighting has been "turned off" because of complaints from local residents. Public opinion is a strange matter. The promptings of a few persons of inexperience and ignorance can sway the emotions of the crowd. To the man in the street, it looks like the war-time street lamp is bright. He feels that if such a degree of light were to be seen streaming from his home, police court proceedings would follow quickly. "Why should we have to obey the strict rule of black-out whilst the local authority ignores it by allowing these bright lamps." It is the obvious duty of the local authority to impress upon these citizens that they're concerned with what can be seen "from above" and not from what is seen at "ground level."
Lighting: ARP


APLE - New Address p6
The offices of the APLE have been damaged by bombing. All the documents of the Assoication were rescued almost intact. The new offices are at 68 Victoria Street, which was the original address when the association was formed.
APLE: Organisation


Obituary p6
Obituaries of C Valon Bennett and J. W. Hampsheir (Director and General Manager of Keith Blackman, Ltd).
Lighting: Personnel


"Safety First" or "Accident Prevention" p6
"Safety First" is a slogan which has been used, misued and abused more than any other. The origin was the old railway rule: "The safety of the public shall be the first consideration of the staff." The use of the word "first" has been dropped as the slogan can be misapplied to mean the reverse, namely a purely selfish motive of self-preservation without regard to others. The title of the Association was altered on the 8th January 1941 to "The Royal Society for the Prevention of Accidents".
Other


Bradford's Electrical Engineer p6
Mr W. Dundas, Deputy Electrical Engineer and Manager of Bradford Corporation Electricity Department has been recommended for appointment as Electrical Engineer and Manager.
Lighting: Personnel


William Sugg & Company, Ltd p6
After recent damage caused to their works in Westminster, William Sugg and Company Ltd, wish to advise their friends that they're able to execute orders for gas appliances without undue delay.
Lighting: Manufacturers


War Lighting Street Lighting And Aids To Movement In Street p7
Summary of a paper delivered to the Illuminating Engineering Society held on the 10th December 1940. It was endeavoured to present the fundamental requirements for its correct application from the psychological and physiological point of view.
(1) The order of illumination is approximately 1/1000th f.c. This is the typical region for "scotopic" or "twilight" vision. Complete adaptation is generally attained after 30 minutes. In the case of elderly people, it takes longer, or is hardly attainable at all. (2) Another point of fundamental importance is the "yellow spot", an area in the eye surrounding the fovea which is highly sensitive under normal illumination levels, but practically insenstive at the levels considered. This makes it hardly possible to perceive objects by direct vision and "size" their limits. (3) Colours are no longer discernable.
The fact that dark adapted eyes are highly sensitive to change of brightness calls for the avoidance of excessive contrast. The maximum brightness of an object in the direct range of vision appears to be .1 e.f.c. and the maximum contrast ratio .02 e.f.c.
The "yellow spot2 being rather insensitive at such illumination levels has an important bearing on the size of the object to be perceived. Looking straight at an object might have the result that it tends to "disappear". Under normal conditions, a constrast ratio of 1:2 might be noticed. At these low levels a ratio of 1:30 would be detected. Proper care should be taken to minimise losses of transmission or reflection by absorption e.g. by dirt on windscreens of vehicles. As to colour effects, red coloured objects become black in appearance, so if one wishes to rely on colour distinction at all, then blue or green should be chosen.
The second part of the paper deals with an attempt to describe how best the above analysed principles should be applied in practice. It was pointed out that light traps serve a secondary purpose by providing gradual stepping (up and down) of illumination levels. It would be advisable to provide an ante-room within the light trap, with an illumination level of .02 f.c., where a person should stop for a short time before entereing the street, to facilitate comfortable adaptation. Conditions outdoors are more complicated owing to the fact that vehicle drivers have other requirements other than pedestrians. Thus traffic signs might be disturbing to the latter. Brightness values of such signs considered as optima in the circumstances are .05 to .1 e.f.c. The "crosses" of automatic traffic signs are permitted to be lit at 1.5. e.f.c. which is somewhat excessive from the visual standpoint. Torches are also unsatisfactory in this respect, and it would be preferable to have them constructed in a box-form with no lens but an even light-giving area of some sq. inches.
In general, investigations prove again the high amenity and comfort value of War Street Lighting System. The illumination shoudl be kept as even as possible, though higher illuminations seem practical if properly controlled.
Lighting: ARP, Lighting: Levels, Lighting: Theory


80-watt Fluorescent Discharge Tube Increases War-Time Factory Output p7
W. A. Smith And Co., Ltd., manufacturers of Bolenium overalls, faced with the problem of maintaining supplies through long hours of winter darkness, have solved their problem with Royal "Ediswan" 80W fluorescent discharge tubes. The Bolenium factory has the distinction of becoming one of the first in the country to employ the industry's newest light source on such a pretentious scale. In the main works bay 127 tubes are installed on 8 foot centres, at a mounting height of 10 feet above the ground. The lamps are housed in Ediswan Industria trough reflector fittings incorpating the choke unit. Offices are canteens are similarly equipped, employing a further 50 tubes. Smith And Co. report that since the installation there has been a noticable rise in output from operatives, upon whom the moral effect of brighter working conditions has been very pronouced.
Lighting: ARP, Lighting: Lamps, Lighting: Lamp Auxiliaries


Sports Under Floodlight p8
There is a growing tendency in New Zealand for night-time athletics. The GEC's Wellington Branch was responsible for a recent installation. 28 GEC standard type floodlights on steel lattice towers 80 feet high have been installed at Lower Hutt, New Zealand. All the units are equipped with Osram 1500W clear gasfilled lamps.
Lighting: Floodlighting


Development In Projector Lamps p9
The use of incandescent filament projector lamps in place of carbon arcs is rapidly increasing. This increase in popularity is chiefly the result of some important improvements over the recent years. The chief characteristics of these lamps are the smallness and brightness of the light source and the compactness of the bulb. These depend on a closely bunched tungsten filament whihc will retain its shape at very high temperatures and a highly refractory glass.
There are three types of design:
  • (1) Those that approximate to a flat disc or rectangle.
  • (2) Those that approximate to a sphere.
  • (3) Those that are cylindrical
Filaments of projector lamps are invariably of tungsten wire. A flat rectangle is arrived at by placing a number of short straight coils side-by-side and producing what's known as a "flat grid" filament.
The need for many different shapes is due to the various optical systems in use. In the projecting lantern, the lamp's grid failemnt is the same shape as the slide, but is mounted at a convenient distance from it. The light from this is then collected by a large lens called the condenser and distributed evenly over the area of the slide.
The optical system of cinema projectors is similar to that of the projecting lantern and the filament has the form of a rectangular grid. In old type equipment, the gaps between the straight coils were filled by a reflected image of adjacent coils from a reflector behind the lamp. Nowadays the same effect is accomplished by closely mounting two filaments in the lamp with the coils of rear filament opposite the gaps in the front filament. This forms a "bi-plane" filament.
There is often considerable vibration. This means that the best shape is not used to prevent touching and short circuiting. The type of filament in which increased clearance is obtained is the "staggered grid".
Lighting: Floodlighting, Other


Singapore Enjoys The Brightness Of Mercury Discharge Lamps p10
A further extension of the large installation of GEC street lighting in Singapore has been completed in Clemenceau Avenue. Decorative concrete columns support the latest design of the GEC side-entry Difractor lanterns with 400-watt fluorescent Osira lamps. The equipment was supplied to the instructions of the municipal electrical engineer of Singapore, C. C. Payne A.M.I.E.E., whose department carried out the installation.
Lighting: Installations, Lighting: Luminaires


The Lighting of A Municipal Concert Hall p11
The municipal concert hall of an important south coast town is a typical example of a war-time lighting problem and its solution. Due to injuries caused by glass broken through enemy action, all glazed lighting units in public buildings need to be treated. As a consequence, unsightly wire cages and guards have been applied in many cases. Another alternative treatment is the substitution of transparent fabric in place of the glass, but is a costly temporary measure.
The ideal solution was, in the view of the GEC, to design a fitting for permanent use, without resorting to the use of glass or fabric.
Each unit used in the design comprises two main spinnings build up on an interior structure and equpped with lamps giving direct and indirect lighting. The centre lamp giving the direct light is masked by the opaque lower spinning, and from oblique vision by additional louvres in the opening at the bottom. The light from this lamp also illuminates the upper trumpet shapped spinning which accommodates a group of lamps throwing light on the ceiling.
The underside of the balcony, and the promenade at the rear of the balcony, are illuminated by means of totally indirect lighting units of all-metal construction.
Lighting: ARP, Lighting: Luminaires


Public Lighting At Aberdeen p12
The effective combination of artifically illuminated windows, underwater lighting and concealed lighting makes the new Aberdeen Public Baths one of the most noteworthy installations since the black-out.
Illumination of the actual pool area, which measures 120 ft. by 42 ft., is provided by 112 200W lamps in silvered glass reflectors for indirect lighting, but considerable additional light is derived from ten 500W lamps housed in floodlights screened by sepcially designed louvres, whilst underwater lighting is provided by 18 Ediswan floodlights accommodated behind watertight bronze posts. Reflected light from this installation provides the light for the artifical windows, which give on to the outer areas comprising the entrance hall, entrance vestibule, cloaks hall etc.
Conversely the light from the outer arae illuminated the windows on the bath side area.
The outer area is illuminated by means of indirect cornice lighting around the walls, with indirect troughs to match suspended from the ceiling.
The lighting installation was designed by the Edison Swan Electric Co., Ltd. under the supervision of the City Architect, Mr. Gardner
Lighting: Installations


The Open Forum: Star Light Fittings by B. D. G. Sandeman, B.Sc., A.M.I.E.E p13
There are one or two strange anomalies in the ARP/37 Street Lighting specification. (1) Why use a filament giving 120 lumens when only 1.4 are required? (2) Why is white colour insisted on? (3) The insistance on a minimum candle power, particularly in the 40° cone about the vertical. In an ordinary square gas lamp, this cone of light is practically obscured, and its utility for low-level lighting is doubtful. If this was replaced by a requirement that the maximum candle power was not to be exceeded, then a great simplifcation in design would have resulted.
The advisory committee was chosen largely from the ranks of the manufacturers, and its natural that they would've framed the specification with an eye to business. Let us combat the suggestion, too often made, that the manufacturers provide the only technical ability in our Association, and our functiona is simply to encourage them. Those of us who were privileged to listen to Mr. Good's address at our Luncheon on November 21st were greatly impressed with his sympathetic and helpful attitude. He said that the specification was not to be considered hard and fast, and that it would be modified in the light of experience.
Let us assume that the specificaitn be altered to include a special construction of lamp and light of a redder colour, together with the alteration suggested above to the minimum requiremetns. A 3 mm. filament, almost a point source, would enable us to use a small reflector, which could be made integral with the lampholder, and a cap over the bottom of the lamp would limit the light vertically and provide the lower cut off. In addition, the filament could be run at a greatly reduced temperature to facilitate construction and give a reasonable life. The writer is confident that such lamps would have a good reception by consumers, who do not relish having to fit the ugly and clumsy abortions which are on sale at present. The other advantage would be the reduction of weight carried by the lampholder.
The same idea could be adapted to the gas lamp, where a glowing central tube could be surrounded by baffles, the whole screwing into the superheater in place of the clay nozzle, and suitable for use without any glass protection.
The second suggestion makes use of the specification as it stands. The illustrated fitting conforms strictly to ARP/37 and differs from the usual types in that it has no lampholder and adaptor. The two halves screw togetehr, gripping the glass of the 15W clear lamp between them. In consequence the fitting is considerably lighter than the present types and elimates adaptor troubles. It could be called a "Lamp Jacket".
There are six zones in the polar curve, each requiring indiviudal attention: the first three, the main beam, with its upper and lower cut off, being the most important. Next is the region between 35° and 65°, when a little light is allowed to spill over from the main beam, by allowing light to escape through teeth cut in an internal baffle plate. The portion between 10° and 35° presents special difficulty and was only accommodated by altering the angle of the skirt. The last portion 0° - &10deg; is catered for by cutting a small hole in the centre of the baffle.
In conclusion, let's express the hope that something will be done to provide a more reasonable fitting than those rushed to market a year ago. The solution lies with the lamp manufacturers what is wanted is an ARP lamp not an ARP fitting.
Lighting: ARP, Lighting: Colour, Lighting: Distribution, Lighting: Lamps, Lighting: Levels, Lighting: Luminaires, Lighting: Specifications


Sodium Lighting In Australia p14
Progress in public lighting continues in other countries. A new and interesting scheme has been installed recently on Storey Bridge, Australia which spans the Brisbane River, Queensland. Both span and approach are lit by sodium. The lamps are 85W Philora for the roadways and 60W for the footpaths, being housed in ELECO Golden Ray refractor plate lanterns.
Lighting: Installations, Lighting: Luminaires


Concrete Columns Stand Up To The "Blitz" p15
Concrete columns are putting up with the bombing in much the same way as the Londoner - "standing up to it."
No concrete columns have fallen to the ground althoguh they've been shattered in parts and knocked about by flying debris. (A picture is included which shows the shattered shaft of a concrete column damaged when a H.E. bomb dropped within five yards of it).
There are nine columns affected badly in the same borough. None of these is out of straight - in every case they have been repaired on site by the company that supplied them originally.
Lighting: ARP, Lighting: Installations


P. Valon Bennett, Assoc.M.Inst.C.E. p15
Has been awarded th Military Cross for bravery. He worked for the Rochester, Chatham and Gillingham Gas Company before being mobilised for active service.
Lighting: ARP, Lighting: Personnel


Public Shelter Lighting p16
Several lighting engineers have added to their work the maintenacne of air raid shelters, which includes supplying lighting for both interiors and exteriors.
An interesting brochure has been published by A. Bell & Co. Ltd. of Nottingham giving details of their range of ARP lanterns. These lanterns can be installed anywhere as they are oil lamps giving at least 100 hours of continuous light. The fitments conform to the requirements of the Ministry Of Home Security whilst in actual design they contain several unique features.
The model "C" is designed for interior lighting having 3-way illumination with obscured glass to give good diffusion. It is fitted with a "Lynlight" burner giving 2-candlepower and 100 hours continuous light on one fuel charge of 1½ pints paraffin oil. Outlet for combusted products is at the back of the lantern for connection to a small length of tube which is inserted in the brick joint of the shelter wall.
The model "E" is for connection to main electric supply and is designed for building in the wall angles of Domestic Communal Surface Shelters. It has two-way illumination with white translucent letter "S". A screwed elbow is embedded in the base to receive electrical conduit and fittings. In case of breakdown of the main supply system the lantern may be immediately converted to oil-burning by the removal of the interior fittings.
The model "D" is designed for Road Blocks, and confroms to the requirements of the Ministry Of Transport. They have 2-way or 3-way illumination with longitudinal slit ½ in. wide with ruby windows. Lamp fitted with an "Adlake" long-time oil burner giving a guranteed minimum of 7 days continuous illumination.
These various types of housing are built strongly and can withstand hard wear. The construction is a one-piece casting in reinforced fine-finish cement-sand concrete provided with air inlets in base. Outlets for combused products from dome at weatherproof and windproof angle. Housing spray painted white, with cast metal door enamelled white, with nickel-plated screws, and fitted with lever lock.
Interior lamp is fitted with long-time burner, with glass chimney at 31 oz. tank with screw filler cap.
Lighting: ARP


Correspondence back-cover-inner
Has the effect of the Purchase Tax on the cost of public lighting been considered? ARP/37 Street Lighting Fittings and ARP Sign Lanterns are in a published list exempting them from the tax. But the manufacturers are invoicing electric lamps and gas mantles plus tax. In our Department, the increase in our annual expenditure is 4,250 for electric lamps and 1,200 for mantles. This covers both street and stair lighting. Perhaps the Government would say this is the right way to indirectly finance the war; but they do so in proportion to the readiness with which they adopt the Government's recommendation to have the permitted lighting.
The local office of Customs and Excise say "Taxable irrespective of purpose." Class 7(d) of "Notice By The Commissioners Of Customs And Excise, Goods Chargeable With Purchase Tax" reads: "Chargeable at the rate of 33⅓ per cent. Electric Filament Lamps (not exceeding 250W) and incandescent mantles; electric dry batteries of all kinds." Neon lamps and discharge lamps are not chargeable. - E. J. Stewart Glasgow.
Lighting: ARP, Lighting: Funding


Street Lighting Notes back-cover-inner
Brief description of the installations at: Hamilton, Dewsbury, Nelson, St. Helens and Eccleston.
Lighting: Installations


Street Lighting In India back-cover-inner
About 40% of the gas sold in Calcutta and Bombay is used for public lighting. The Bombay Gas Company has obtaiend a renewal of the public lighting contract for a period of 8 years, starting from March 1st, 1940. This entails the lighting of 8,721 lamps with 24,142 mantles.
Lighting: Installations


Adverts: The General Electric Co., Ltd, A. Bell & Co., Ltd., William Sugg And Co., Ltd., Siemens Electric Lamps And Supplies Ltd., Metropolitan Vickers Electrical Co. Ltd, British Commercial Gas Association, The British Thomson-Houston Co. Ltd., British, Foreign And Colonial Automatic Light Controlling Co., Ltd. and Holophane Ltd..