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ilp archive : journals

public lighting no. 17 vol. 5
April 1940


Editorial p29
Black-out is taking its toll upon the nerves of the people. The rigid lighting restrictions which have existed since the outbreak of war have been partially lifted, thanks to the persistent energies of the lighting engineers, and there is now no excuse for a city or town to remain in perpetual darkness. There are still a number of towns of large size which haven't installed the new low-intensity lamps. The plea of the councillors is "it is too expensive" or "for the small amount of light given, it is not worth the money." But why shuold public lighting be withheld on the excuse of economy? This is because street lighting is left to the decision of the local authority itself, and hasn't had its use dictated by a Government Department (unlike other ARP services such as Fire Service, Air Raid Shelters and Ambulance Service.) Low-intensity lighting may no be idea - but if it gives a degree of comfort to the pedestrian, assist the road user, and reduce the number of accidents (which has already been proved), then the expese warrants it. Public Lighting has set its aim at securing war-time lighting for all towns. Much of the excellent work they have carried through with such splendid efficiency for ARP will be chaotic in a moment of emergency if an air raid takes place on a very dark night with no street lighting.
Lighting: ARP


Is It Worth It?
Ever since the Ministry Of Home Security recommended that modified street lighting should be installed as soon as possible, many towns have decided to convert all their street lighting lanterns for use with "starlighting" fittings. There was some disappointment with the low intensity of lighting allowed, which amounts to no more than one-thousandth of the accepted standard. However, aerial observations, have established that any brighter lighting would create a pattern easily identified by enemy aircraft, even from considerable heights. The considerable advantages are now being increasingly appreciated. The greatest benefit will be derived by pedestrians, whilst the motorist will appreciated the view of the perspective of roads which had become lost owing to the short beam emitted by the new headlight masks, and not being dazzled by torches carried by pedestrians. In addition, the psychological effect of the black-out is bounded to be beneficial to the social life of the community. The inestimable value of light in the event of a night air riad is too obvious to be emphasised: yes, it is worth it.
Lighting: ARP


The War Will Not End By Next Winter
Captain Wallace (Transport Minister) said "I am not one of those who believe that we can settle with the Nazis before next winter, and I can assure you that the difficulties of black-out working are fully appreciated by the Government."
Lighting: ARP


APLE District Meeting, Leicester
The first of a series of District Meetings was held in Leicester on April 5th, 1940 for the purpose of explaining the technical details of the new low-intensity street lighting fittings, and to provide a practical demonstration of such fittings in actual use. Mr P. Good, Chairman of the Joint Lighting Committee, presided over the meeting which was addressed by Mr. F. C. Smith, the President of the I.E.S. who gave an explanation of the BSI Specification, and Mr. F. C. Johnson, Assistant Undersecretary for State, Home Office (ARP Department). Mr. J. M. Waldram demonstrated aerial observations of the new lighting as seen from varous heights. The visitors later had an opportunity of observing a range of low-intensity electrical and gas units, installed in roads adjacent to the hall. These had been fitted under the supervision of Mr. Thomas Wilkie, the Public Lighting Engineer of Leicester.
Lighting: ARP


Institution Of Gas Engineers
The seventy-seventh annual general meeting of the Institution Of Gas Engineers will be held in London, subject to conditions, on the 4th and 5th June, 1940
Lighting: ARP


Street Lighting Overseas p30
One of the many disadvantages of blackout is that facilities for testing and experiment have been severely restricted and progress in street lighting has slowed. Many overseas authorities have taken a vivid interest in these leading street lighting improvements, and orders are still coming in. The factories of the GEC are still continuing to work to fulfil overseas orders, and are dispatching equipment to all parts of the Empire e.g. installations are still being installed in South Africa, whilst Osira lamps are becoming increasingly popular in India, and there have been large orders from Australia.
Lighting: ARP


BS/APR 37 p32
Street lighting in a modified form is now permitted, and a specification has been approved by the BSI, which is the new standard ARP/37. Manufacturers have lost no time in getting into production.

GEC
The GEC is manufacturing units for 20' nominal mounting height which are rated at 60W. The range has been extended to include units for use with 40W lamps at 15'; and 25W and 15W lamps at various heights. The units which are either: (1) Held rigidly by the existing lantern body; (2) Supported from the existing lampholder; (3) Comprise entire weatherproof units which can be screwed onto bracket arms. Fixing to the lantern body is recommended in all possible cases and is considerd essential for lanterns suspended from tall columns or traction poles where considerable vibration exists. In designing this type, the main consideration has been to ease in fixing to existing lanterns to avoid the cost and labour involved in removing lanterns or rewiring them. The unit consists of two main parts, the light controlling device and its fixed support. Where units are supported from the lantern body, rewiring of the lampholders or existing leads can be avoided by the use of a special GEC connector. This consists of a flexible lead with an adaptor at the end for fitting into the existing lampholder and at the other end the lampholder for the new unit. There are two ranges of units employing different optical systems, providing correct light distribution: one designed for 15W/25W lamps, and the other for 40W/60W lamps. While the 15W/25W lamps provide sufficient light, the more robust higher wattage lamps are favoured by many engineers for withstanding the vibration at the top of tall columns, particularly traction poles, due to traffic and windage.

The Z3200 range for 60W and 40W lamps is constructed of lead-coated sheet steel incorporating a special lighting device. This consists essentially of a secondary light source provided by a flashed opal glas disc accurately screened by a perforated metal plate. The light control is completed by a second screen. The bottom is detachable for maintenance. All three methods of support are available.

The Z3210 range of units for 25W and 15W lamps is constructed of spun steel and incorporates a lighting device consisting of a flashed opal cylinder with surrounding metal grid to provide the correct light distribution and intensity. The bottom is detachable for ease of maintenance. Units of this type are supplied for different mounting heights and all three methods of support are available.

Siemens
Approved by the British Standards Institution for mounting heights of 19' and upwards, at a spacing in plan of not less than 100', when fitted with 25W pearl lamp. When so installed a general level of illumination of 0.0002 foot-candle will be provided and howhere will the value exceed 0.004 foot-candle. The fitting consists of a standard 12" diameter R.L.M. Reflector, stove-enamelled black inside and outside, carrying an annular slotted mask so designed and located as to procude the desired light distribution. The exterior of the mask and the interior of the bottom portion are stove-enamelled black; the cylindrical upper portion is stove-enamelled white inside. Access for cleaning and relamping is provided by the removal of the bottom portion of the mask. In designing this reflector the Siemens lighting engineers have aimed at producing a fitting giving its resutls through the medium of large areas at low lighting intensities e.g. the reflector is flashed to a depth of approximately 2¼" whilst a reasonably broad ring of light is emitted from the slot in the mask. In this fitting the mask is fixed to the top of the reflector.

BTH
The company have designed and produced a lantern depending for its precision and permanence of performance on the use of die-cast parts which are accurate to a thousandth of an inch, and which cannot be deranged or distorted by even the roughest handling. Since BS/ARP37 states that the lantern must be rigidly fixed in a vertical position, it is desirable to mount the new lantern directly on the bracket arm, either in place of the existing lantern, or by adding an extra bracket. This arrangement may also be found to be less expensive than suspending the new lantern from the existing one. If it is decided not to do so, a range of electrical connectors and mechanical suspension types are available which enables the ARP lantern to be readily attached to most types of existing fittings. There are four models, which only differ in the dimensions of the light control apertures to provide the correct distribution for each mounting height. The lantern body is not fitted with a lampholder; this must be ordered with the lantern body to make up a complete assembly.

Ediswan
The lantern is a precision lighting unit, with vitreous enamelled components designed espressly to maintain initially efficiency without constant maintenance. Therefore the use of wire gauze, finely pierced metal or glass reducing screens have been avoided. The fitting contains two refelctors, constructed as a unit on the over-lamp principle, the light gap being masked to adjust light output accordingly to mounting height. Each fitting is clearly marked indicating the mounting height at which it should be fixed with a 15W pearl lamp. The reflector and cup forming the lower part of the fitting are so fixed that they can be quickly detached for lamp renewal and cleaning. A die-cast and tapped top at the head of the fitting will make it possible to fix direct into existing lanterns without the use of special adaptors. Where this is found impracticable, a special type of adaptor is available for fitting into BC, ES or GES lampholders.

Wardle
The Wardle Adapter Type and Bracket Type Restricted Street Lighting Fittings comprises an upper and lower steel spinning with a cup-shaped baffle. The fitting in each case is of robust construction and is sufficiently strong to withstand rough handling during erection and lamp changing. The method of assembly ensures maintenance of initial performance and when replacing lamps it is impossible to modify the gap between spinnings. The Adapter Type fitting is suitable for direct connection to the lampholder in existing street lighting fittings. Approximately 13" diameter and 5 3/8" deep.

Crompton
The Crompton ARP Street Lighting Lantern is designed to conform with BS/ARP 37. Fitting has been produced after considerable experiment, and scientifically designed not only to ensure that light output complies with the Specification, but to provide simplicity of installation and ease of maintenane. Of robust construction, its fitted with a die-cast cap tapped ¾" conduit, the reflector and body beening 22 gauge sheet metal, which is finished outside in black enamel, and the interior in white enamel, the reflector being battleship grey. Access for relamping is by means of the top flange, which is held in position by two thumb screws and a bayonet catch, and lamp replacement is an extremely simple operation. When the lantern is to be used at a mounting height of 10' it employs a 15W pearl lamp, while 24W and 40W pearl lamps are used in the 15' and 20' mounting height lanterns. The bare lamp is not visible from any angle. A range of GES, ES and BC adaptors is available for connection to existing lampholders.

Simplex
This fitting is unique as the whole of the optical assembly, sealed in a clear glass cylinder, can be detached for relamping and reassembled in a few seconds. Outstanding features include: The candle-power and the shape of the polar curve are controlled by selective absorptions of unbreakable, opaque metal parts, and are not dependent on the reflection or transmission of white reflectors or opal glass; the whole of the optical assembly is absolutely dust and insect proof, being sealed with a glass cylinder, with soft rubber gaskets; the use of a 15W lamp for all of the specified mounting heights is afeature of this design; and a range of Simplex adaptors both rigid and flexbile are available for use with the 1½" hole type fittings - these allow the Starlite fittings to be attached quickly and easily to many existing lighting fittings without rewiring.

Metrovick
The Starlight street lighting fitting is nearly constructed with a light cast canopy and bottom disc, while the body is a single pressing. Two brass thumb screws permit easy lamp replacement. Dust and small insects are prevented from clogging the fine mesh inside by means of a small glass cylinder held between two rubber sponge gaskets. Electrical and mechanical adaptors of all types are available, including adaptors to permit fixing to existing lanterns. Weatherproof cast canopies drilled and tapped for conduit entry can also be supplied.

Holophane
Holophane 302 Street Lighting units have been designed in accordance with the requirements of BS/ARP 37 for street lighting under war-time conditions. The general level of illumination provided by the specification is 0.0002 ft. candle and nowhere on the road shall the illumination exceed 0.0004 ft. candle. The B.S. specification publishes three sets of limiting vertical light distribution curves and any lantern used for street lighting must be within the limits of these curves. The lanterns give a relatively uniform illumination along the road and should not be spaced at less than 100' apart. The smallest GLS available is 15W which gives a mean spherical candle power of 10, so that it is required to provide a fitting which will reduce the bare lamp intensity at 75° by one-tenth and at 0° by over a sixtieth. This is accomplished in the 302 by a method which is provisionally protected by patent No. 32075/39. The unit consists of a partially obscuring cylinder placed around the source in combination with a secondary baffling member in the form of an inverted cone. The lower section of the cylinder is so constructed as to allow the spcified intensity to be emitted at angles from about 65° to 85° to the vertical while the function of the combination, cylinder and cone, provide the very subdued general intensity required at angles below 65°. At the base of the cylinder is formed a flanged opaque cup which is fixed in a definite position relative to the lamp filament. The fitting is completed with a bowl shaped reflector giving a cut-off at about 85° from the vertical. The unit gives a large area of low luminosity that is a distinct aid to vision.

REVO
After many experiments and tests, REVO have produced a unit which complies with BS/ARP 37: scientific design and permanent optical control; light output cannot be disturbed; rigid assembly unaffected by handling or lamp changing; fitted with GES, ES or BC adaptors for connecting to existing lampholders; vitreous enamel finish. There is a unit for every mounting height now certified by the British Standards Institution.

Lighting: ARP, Lighting: Distribution, Lighting: Levels, Lighting: Luminaires, Lighting: Manufacturers, Lighting: Specifications


Tewkesbury Gas Lighting Scheme p34
Description of the installation in Tekesbury.
Lighting: Installations


East Grinstead p34
Description of the installation in East Grinstead.
Lighting: Installations


Multiple Purpose Motor Vehicle For Lighting Department Use by Ronald Parker (Lighting Department, Aberdeen) p35
The heavy initial cost and standing charges of motor tower waggons are not justified unless they can be kept in constant use. So most lighting authorities rely on hand operated telescopic platform ladders. Aberdeen Town Council Lighting Department purchased equipment early in 1939 when the need of a mobile tower ladder for maintenance and a motor lorry was essential.
The ladder is of tubular steel cosntruction and was manufactured under a Swedish patent and supplied by Messrs. John Kerr And Co. (Manchester) Ltd., Northwich, Cheshire. It consists of a double section extending ladder mounted on a turntable which moves on a shaft slotted into a base plate. To the top of the ladder is attached a sheet metal tray to hold tools, glassware etc. When lowered, the ladder rests on, and is securely strapped to, a cradle attached to the foredoor of the lorry dray. When fully extended the ladder gives a working height of 35'.
It has been found that two men can work on the ladder together, one sitting and the other standing. Erection work cannot be done as easily as with a tower waggon, but for general maintenace, cleaning and the like, it has proved to be at least its equal. It also has several advantages: one is how centrally suspended lamps can be cleaned from the side or the road.
The lorry with the ladder may alos be converted quite quickly into a crane. It may be elevated to either of two fixed angles by a simple adjustment of the length of a chain. In the higher position, the one normally used, poles up to 10 cwt. may be raised; in the lower position the load must be restricted to 7&frac;12 cwt. With the crane it has been possible to erect poles at an average rate of 8 per day, including the digging of holes, and the transport of materials by the lorry.
Acknowledgement must be made to Mr. J. F. Colquhoun, Sheffield who evolved this type of crane several years ago.
The lorry used is an Albion 30-40 cwt. over type vehicle of standard design execpt that the members of the chassic frame and the road strings have been strengthened.
The total cost of the lorry, ladder and crane equipment was 584.
Lighting: Equipment


Low Intensity Lighting "On The Air" p36
Secretary of the APLE, Mr. H. O. Davies appeared on the radio programme In Britain Now and gave a short talk on the new Starlight Lighting. The talk aimed at interesting the public on the value of this form of war-time street lighting. Numerous messages were received from all parts of the county - the attempts to give even a minimum amount of light was met with great satisfaction. Many listeners enquired "why their own towns were still without light?"
Lighting: ARP


Hire Contracts p36
The Automatic Light Controlling Company Limited, who make "Gunfire" Gas Controllers and Time Switches sent the following letter to their customers: "We have decided under the circumstances to make NO CHARGE for the hire of Controllers and Time Switches out of use owing to hostilities after September 1939, until such time as the restrictions are agains relaxed, but it must be understood that this "Black-out" period be added to the original contract period.."
Lighting: ARP, Lighting: Manufacturers


Warning System For ARP p36
Ashford is only 10½ miles from the sea shore and comes within the restricted area and would not be allowed to install even reduced lighting. The Electrical Engineer, Mr. H. Wilson states: "At the start of the war we went to some trouble to get all our public lighting under central control, and we were rather hoping that we should be able to use it, and put it out on receipt of an air raid warning. When it became certain that this would not be allowed, we used the centralised system, which was idle, for purposes of air raid alarm." There is a separate street lighting conductor all over the town, and connections from this are carried into most of the houses in the underground service cable which supplies the house. It is possible to use this conductor for ARP warnings. When the current is interrupted by working a push at ARP Headquarters, the relays in wardens' houses all close and ring the bell from a battery near the bell. Any signal sent out from ARP Headquarters is thereby transmitted to these bells in less than two seconds.
Lighting: ARP


Emergency Street Lighting: An Explanation Of The Specification BS/ARP 37 by F. C. Smith, M.Inst.Gas.E, F.C.S p36-1
It has been established that the black-out is an essential factor in defense against aerial attack and the Lighting Restrictions Order is the logical outcome of this conclusion.
This Order has imposed additional strain on road users, increased accident risk, added to the difficulties of police supervision, restricted evening education and curtailed many desirable phases of social life.
These facts are recognised by the authorities. The Ministry of Home Security insisted that the Committee dealing with ARP lighting shuold regard the street lighting problem as of the utmost urgency: with the least possible dealy a form of lighting should be developed which would provide the greate possible amenity without giving assistance to enemy aircraft.
It was clear from the outset that the Committee would have to accept certain limitations in regard to the distribution of light. Under peace-time conditions, many well designed installations emit a considerable amount of light in an upward direction, and this is to some extent responsible for sky glow. This condition is obviously unacceptable in war-time. Accepting this limitation, the problem resolved itself into determining the amount of light that could be used.
The first stage was to observe from the air areas with street lighting installations which were under control. In these controlled installations it was possible to vary the illumination produced on the road. It was established that the highest illumination that was consistent with the requirements of defence was of the order of 0.0002 f.c.
A difficulty encountered by the Committee is that weather conditiosn are rarely suitable for the aerial observations required. In consequence, Mr. Waldram of the GEC, Wembley, proposed and developed an optical method which it may be possible to indicate the height at which a pattern of the scene as viewed from the air will be revealed at various levels of road brightness. (Where Brightness is illumination x reflection factor of the surface.) Such a method would obviously require correlating with actual aerial observations, and the results to date indicate that it may be possible to anticipate with fiar accuracy the height at which a pattern will be revealed. Waldram's method was in fair agreement with the actual aerial observations and confirmed that an average illumination exceeding 0.0002 f.c. cannot be permitted. The method was demonstrated in London at three meetings arranged under the auspices of the Joint Lighting Committee at the Empire Resturant Victoria, on the evenings of February 6th, 7th and 8th.
It is very difficult to visualise the amenity value to the public of this very low order of illumination. The illumination from a full moon on a cloudless night is 0.02 f.c. whilst that from starlight on a cloudless light is 0.00008 f.c. It is a matter of experience that pedestrians can find their way about and avoid obstacles with ease on a moonlight night, and that a bright starlight night affords some assistance especially if obstacles are painted white. A superimposed illumination of 0.0002 f.c. from the street lighting installation will not be of any great assistance on a moonlight night and is only of limited assistance on a bright starlight night.
On the occassion of meetings held at the Empire Resturant, a conducted tour of the streets illuminated to the 0.0002 f.c. level was made by 500 people who represented many of the Lighting Committees from all parts of the country. Without exception all agreed as to the immense amenity value of this order of illumination.
A specification "Street Lighting under War-time Conditions", under reference BS/ARP37, was issued in January 1940, and was issued by the British Standards Institution.
The considerations which led the Committee to adopt the requirements set out in the specification are:
(1) Illumination should be the maximum permissible from the aerial observations is not exceeded. Also provide a ready means whereby the administrative authority cane be assured in respect to this requirement.
(2) The economic aspect is a matter of considerable importance. It is absolutely necessary to make sure of existing columns and to accept as inevitable any limitations which may be imposed by the spacing. (Any other solution would require the use of materials, labour, and unnecessary road work.) The lighting units should be simple, provide the required distribution without expensive directional equipment and should be consistent with reasonable fixing and running costs.
(3) The distribution chose, always accepting the limitation that no light is allowed above the horizontal, should give without appreciable glare the maximum amenity for the more usual spacings met with practice.
For (1), the practice hitherto followed in street lighting specifications prior to the Final Report has been to classify installations in terms of mean test point illumination. It may be urged that BS/APR 37 could have followed this precedent, and have stated that the illumination should not exceed the stated value. There are two ways to verify the installation: measurement or calculation. The difficulty of verifcation by actual measurement is readily appreciated by those experienced in the measurement of intensities of the order of 0.0002 f.c. but even to the layman, bearing in mind that moonlight may produce an illumination of 100 times, and starlight 30% of the value to be measured, it will be clear that great difficulty in obtaining reliable results must be experienced. Calculating values also presents inherent difficulties. Such a suggestion would somewhat encourage the production of a large number of units and bring about a delay in production.
There fore the Committee took the view that four units should be specified:
(1) A unit for use at a nomimal mounting height of 10' which may be used at any height between 9' and 14', provided the distance along a line of joining units in plan is not less than 100'. (Can also be used at height between 14' and 19' if distance between columns is less than 100' but more than 75').
(2) A unit for use at a nominal mounting height of 15' whcih may be used at any height between 14' and 19', where the distance between columns is not less than 100'. (Can also be used at height of 19' or more if distance between columns is less than 100' but more than 75').
(3) A unit for use ata a nominal mounting height of 20', where may be used at any height from 19' upwards, where the distance between columns is not less than 100'.
(4) A unit for use at a nominal mounting height of 10' which may be used where the distance between columns is less than 100' but not less than 50'
The unit to comply with the specification must have a curve which lies between A and B on the polar diagram.
It is only necessary to verify that the right type of unit has been used at the correct mounting height and at a spacing equal to or exceeding the minium allowable for the authority to be satisfied that the regulations have been complied with. The question of mounting height and distance apart can be verified by simple measurement on the street.
The average light output from these fittings is of the order of 4 lumens. A pre-war lighting unit may have a lighting output between 8000 and 10,000 lumens. Therefore the light must be spread out evenly to obtain the best result. Therefore the inner and outer frameworks of the photometric curve ensure a distribution of the requried directional type and place upper and lower limits upon the intensities. Different distributions are possible although a definite restriction is imposed. It is advantageous for the curve of the fitting to hug the top of the framework since this determines how many light sources can be seen along the road. If two or more fittings can be seen, the added facility of a line of beacons marking out the direction of the carriageway is obtained, to the advantage of road users.
The maximum candlepower permitted at any angle in these fittings is 1.5 c.p. For purposes of administration it has been deemed necessary that all units should bear a certification mark from the British Standards Institute. This body arranges for a test to be made ata recognised standardising laboratory. If the fitting proves satisfactory, the manufacturer is required to satisfy the BSI that his manufacturing facilities are such to ensure reproductibility. In addition, the manufacturer must, from time to time, submit to the BSI tests of units made in an approved laboratory from samples taken at random from production stock. If these are satisfied then the manufacturer is permitted to use ther certification mark.
In addition, the specification lays down certain requirements in regard to mounting and erection and insists that the unit should be mounted vertically. A further clause deasl with construction and requires those parts that control the optical properties shall not be liable to variation or derangement in maintenance or use. The materials and construction shall also be robust.
For capital expenditure, the Ministry Of Health would consider a loan, which would be repayable in 5 years.
It has been suggested from time to time that higher orders of illumination might be permitted if the installation were under centralised control. This aspect has been given the fullest consideration and it is not considered for a variety of reasons to be the correct solution. The main advantage of restricted lighting is that it can remain on during a raid. There is no doubt that in the period immediately preceding a raid, epsecially on a dark night, the amenity value to the public of this restricted lighting in finding their way to a shelter is of the utmost value.
Lighting: ARP, Lighting: Control, Lighting: Distribution, Lighting: Funding, Lighting: Levels, Lighting: Specifications


Restricted Lighting By Gas by P. Crawford Sugg, B.Sc.(Eng.) p37
Shortly before the War, the Home Office called for a specification for lighting fittings, both gas and electric, which would give an even illumination of 0.002 horizontal foot candles on the ground at a spacing height ratio of 4 to 1. Faced with this previously unheard of requirement, the design staff at first sat down and laughed at each other.
This fitting had to be designed and produced at a price far cheaper than any previous gas lighting unit. It had to be very simple in construction and so designed that every part fulfilled as many duties simultaneously as possible. Also it had to take the form of a conversion unit to fit existing lamps so their weather-proof qualities could be used to stabilize the fitting. The design of the fitting was required for rapid publication as a BS/ARP Specification so that what, at first glance, appeared to be an insoluble problem, had to be solved and put into practical form in a few weeks.
So part of the laboratory staff determined the form of a suitable light distribution, and the other half modified the photometric apparatus so from measuring 5,000 c.p., it would measure 30 c.p.
The decision to concentrate fully on a fitting which converting an existing gas lantern of the globe type was a great assistance, it being realised that the ideal position for the converting unit was in place of the globe of the existing lamp. In this position, the fitting was rendered weatherproof by utilising the flue of the existing lamp.
Consistency of light output was essential and it was soon realised t hat the diversity of numbers and sizes of mantles made it essential, despite the cost involved, to dispense entirely with the use of existing burners and to include a complete auxiliary burner as part of the conversation fitting itself.
Thus it became unnecessary to examine each particular lamp to determine its burner size; all that was required was the globe diameter. This feature also enabled a marked economy in gas consumption to be realised, as the light produced by the auxiliary burner was no greater than was requierd to suit the optical system and to control the distribution.
It must be remembered that the conversion fitting had to fit all types of lamp and had to be standardised as far as possible in order to make its production possible in bulk at the required price.
The experience gained in stabilising street lighting lamps of the cut-off type, this is fittings having reflectors with deep sides, showed it would be desirable to admit the air required for the conversion fitting from the gas lamp to which it was attached, and not from independent entrances in the conversion fitting (which might also emit stray light).

Forming The Polar Curve
In early experiments the auxiliary burner was fitted with a limina mantle, consuming 1 c.ft./hr., and by surrounding this with a small silica diffuser globe a source of low brightnessand considerable size was obtained. The polar curve (theoretically necessary to obtain an even illumination of 0.002 h.ft.c. for two fittings mounted 10' high and 50' apart) was examined and it was decided that the necessary candle power of approximately .2 vertically beneath the fitting could be obtained by indirect light reflected from a matt painted shade, all direct light downwards being obscured by a metal cup below the source, which was supported from the shade by three iron straps. At the same time the bottom cup could be of such a diameter as to cut off excessive light at angles of about 50°-60° from the vertical.
A considerable variety of shades and cups were therefore made up and one week of hard work on the testing apparatus sufficied to produce a fitting the polar curve of which was a reasonable approximation.
The experience gained in this way facilitated completing the fittings suitable for 15' and 20' mounting heights where a Bijou mantle was adopted, and the resulting designs were incorporated in BS/ARP 16. By this time we were at war and the production of these fittings was immediately put in hand for supply to exempted premises, such as railway stations etc., and was followed by the design and publications of fittings for 0.02 h.ft.c. (BS/ARP 20) and 0.2 h.tf.c (BS/ARP 21), each of which was carried out for the three nominal mounting heights of 10', 15' and 20'.

The Need For Street Lighting
The bewildering consequences and restricting influence of the black-out led to the consideration, in conjunction with the Defence Authorities, of the possibilities of some form of amenity lighting in the darkened streets to reduce risk and enable the necessary social life of the community to continue. The provision of lighting units for the experimental installations at various levels of illumination was greatly facilitated by adapting the 0.002 fitting, but the insertion of various absorbing devices for the lower mounting heights, and by using the 10' moutning height 0.002 fitting to give 0.0002 ft. candles at 20' mounting height. In this way changes in illumination level were effected by short notice.
A specification, BS/ARP 37, was immediately drafted to enable these successful results to be reproduced elsewhere with accuracy, and complying fittings should have the B.S.I mark of approval.
All experiments had been based on the use of the small limina mantle and it was felt by the majority that the standard No. 1 or Bijou size mantle would prove a more suitable and consistent lgiht source for gas fittings, despite the relatively slight increased gas consumption.

The Westminster Installation
Faced by an official request for an immediate large-scale installation in Westminster, it was necessary to re-design completely for the new source and produce some hundreds of fittings suitable for converting both high and low pressure gas lamps within a period of ten days. The method adopted was to put into immediate production the main parts of the fittings: the auxiliary burner, reflector and bottom cup and to erect these in lanterns existing in the streets. Meanwhile, the laboratory staff, working in shifts, devised the slotted masks which primarily controlled the light output for the three mounting heights, the slots being cut out by milling overnight and the resulting masks, with various numbers and sizes of slot, tested the following day. When the sizes of slot had been determined, formed tools for punching these were used. The production model masks were then retested, approval sought for the resultant polar distribution and the bulk production started, the masks being inserted into the previously erected fittings. Only true co-operation between the various bodies concerned, especially the B.S.I. and the Public Lighting Department of the G.L.C.C. enabeld this installation to be effecteed by the specified time limit.

The Certified Fitting
The attention of the laboratory was then directed to the design of the fittings to comply, not only with the light output, but in every other respect with the requirements of the specification, which was now in completed form. It was undesirable that the masks should be removable and a high degree of consistency in mechanical construction of the optical parts was required. The optical portion of the fitting was therefore re-designed so that its parts could be produced to close limits, either by spinning or stamping operations. The polar curve resulting was refined by the use of ther three series of slots as has been described elsewhere.

Tolerances
As soon as a promising design had been completed, the effect of possible variations in the detail was examined and suitable limits determined to suit the specification. The effect of variation in the transmission of the silica diffuser was very carefully investigated. The tests were satisfactory.

Finish
The type of paint was also investigated. The fittings, owing to war-time restrictions on material, were made from sheet iron and steel and therefore could only be expected to have a reasonable life if properly protected. Consultation with the paint manufacturers and numerous trials for consistency of results, produced a finish which, whilst cheap, is generally considered satisfactory. Each iron or steel part of the fitting is dipped in a red priming paint which possesses certain rust inhibitive properties and neutralises the effect of any lubricant which may remain on the surface of the metal. Certain parts are then finish painted, assembly completed and the final finish applied, followed by marking in the appropiate colour.

Gauges
The tolerances which were found to be permissible formed a basis for a gauging scheme, by which all essential parts are checked, in some cases 100%, in other cases by sampling. The number of gauges is nineteen. The tolerance on the slots in the masks is 0.002" and the position of these slots is accurate to within 0.005".

Routine Testing
One fitting is taken from approximately every 1000 manufactured, a test taken in the lab and the result sumbitted to the BSI for inspecition. These tests have shown that a very high degree of consistency has been attained. In producing the certified fittings over 300 complete tests, each representing some modification, were recorded, in addition to numerous partial tests.

Lighting: ARP, Lighting: Distribution , Lighting: Installations, Lighting: Manufacturers, Lighting: Levels, Lighting: Specifications


The Late Mr. C. F. Spencer p40
Brief obiturary of Charles F. Spencer, for 17 years the chairman of the Edison Swan Electric Co. Ltd..
Lighting: Personnel

National Illumination Committee: Annual Meeting and Report p40
It is the representative body for the subject in this country. It is affiliated to the International Commission on Illumination. Brief summary of its Annual Meeting.
Other


War-time Street Lighting: Gas Fittings and Their Installation p41
The first thing to appreciate with the new "0.0002" lighting is that it is not sreet lighting in the commonly accepted sense, and nearly all things held dear in the past must go by the board when installing this new "comfort" lighting.
In the past we have strived to privde the maximum visibility; now we must now strive to exceed a limit which is far below that we used to achieve. We must, in some cases, light alternate lamps and our photometers are doomed to rot in their cases.
This state of affairs is due to that much maligned thing, BS/ARP 37, and since the only lighting allowed in the streets must conform to its requirements, there is no course but to face the facts and do the best we can within its framework. Although the lamps will provide useful illumination on only about one night in three because of the phases of the moon, pedestrians and drivers are forced to admit that, when there is no moon, with the aid of illumination from these units, they do not bump into fellow-walkers or fall up and down kerbs, or embrace lamp standards, as they did before these "glow worms" appeared.
For gas, there is a standard lighting fitting, which is slightly varied to meet the requirements for different mounting heights, and adaptors of special design are fitted to facilitate fixing to different types of lamps. The upper portion of this standard fitting supports the burner, and the lower portion, which is hinged to the upper part, forms the optical system controlling the light output. The burner is of the ususal type with needle gas regulator and air-regulator, and is fitted with one bijou mantle of standard size and shape. The designed gas rate is 875 Th.U. per hour.
The lower portion consists of a top shade and bottom cup which are clamped together by means of three screwed rods, with a slotted metal cylinder forming the spacing agent. The shade and cup are similar for all mounting heights, but the slots in the cylinder and the shape of the "control ring" are varied to give the different outputs required for different mounting heights. Although the slots in the cylinder are of different pattern for each height, it may be stated generally that there are three series of slots. Those in the top set of horizontal, and the control ring prevents light passing out except at lower angles around 30° to 40° above the vertical. The second set of slots is set vertically and these allow the light for the main "beam" - above about 65° - to pass. The lower set of slots - again set horizontally - are not visible from outside the fitting, their purpose being to pass light to floodlight the underside of the shade to provide general illumination at the vertical and lower angles.
The silica cylinder surrounds the mantle to provide a large diffused light-source, and a clear glass cylinder is also used when the fitting is not fixed inside a windproof lantern.
For panel type square lanterns, or circular lanterns, a type of swan-neck fitting is provided, and the unit is simply screwed on the gas supply in the lantern. For globe lamps, the unit will be fixed in an adaptor which fits in the globe ring.
To meet the requirements for different mounting heights and types of lamp, well over 50 variations of the unit and the adaptors will have to be supplied.
Manufacturers of gas conversion fittings are William Edgar, Falk Stadelmann, Foster and Pullen, C. H. Kempton, William Parkinson and William Sugg.
Lighting: ARP, Lighting: Distribution, Lighting: Levels, Lighting: Specifications


The Newest Electric Lamp - The Crompta Fluorescent Tube p42
The Crompta Fluorescent Tube is an entirely new electric lamp development. It is a type of discharge lamp in the form of a white glas tube five feet long and 1½" in diameter, and within ultra violet light is generated. The tube is lined with a layer of fluorescent material which converts the ultra violet energy into light which is a precise reproduction of daylight.
The result is a lamp which illuminates colours in their perfect daylight relation and gives remarkably shadow free lighting. These qualities make it ideal for use in all positions where a well distributed source of light is needed or perfect colour matching necessary.
The lamp generates less than half the heat of an equivalent filament lamp, although giving three times the light. Its consumption is one third that of a filament lamp of equal wattage and its life twice as long.
Full brilliance is attained almost the insant of switching on and the lamp may be re-lighted if desired immediately after switching off.
The lamp is rated at 80W and operates off 200-250VAC. The light output is 2800 lumens and the efficiency consequently is 35 lumens per watt, while its life is 2,000 hours, and the power factor .9 lagging.
The only auxiliary equipment needed in addition is an unobrusive unit which contains a choke, radio interference suppression condenser and a starting switch.
Lighting: Colour, Lighting: Lamps, Lighting: Lamp Auxiliaries


War-time Street Lighting by Gas p42
With over 800,000 gas lamps in this country for street lighting purposes, it is not surprising to learn that installations or sample installations of new-power gas lighting fittings are being erected for over 300 local authorities.
Lists of authorities follow.
Lighting: ARP


Concrete Bollands p43
Concrete Utilities have started to develop concrete bollards and propose to make a variety of "Aids to Movement" in this medium. The number of advantages are a high-class finish, extraordinary strength, ease of maintenance and low first cost. Three designs are available. For war-time conditions, the bollard is fitted with a stamping in the form of a cross complying with regulations; a blanking pate to screen the white panel, and a detachable head piece. When normal times return, all that is necessary is to remove the sign plate and blanking plate thereby allowing the normal lighting to fall on the whole length of the panel. If desired, the head piece can be lifted off, giving easy access to the fixing of "Keep Left" illuminated panels of standard design.
Owing to the high-class finish obtained with good concrete, these bollards paint easily if desired. The strength of the bollards is quite exceptional and they have tremendous resistance to heavy treatment.
The bollard has a junior partner in Tom Thumb which can be used to cover hurricane lamps, gas lamps or electric lights. Stamped plates are supplied with crosses, "IN", "OUT" and in red.
Lighting: ARP, Lighting: Manufacturers, Lighting: Materials, Lighting: Signs


The Late Sir Francis Goodenough, C.B.E by Captain W. J. Liberty p44
Obituary for Sir Francis Goodenough who was a founder member of the APLE
Lighting: Personnel


Street Lighting Notes p45
Brief description of the installations at: Aberdeen, Accrington, Ayr, Bournemouth, Bristol, Caernavon, Coventry, Crook and Willingdon, Coulsdon and Purley, Croydon, Doncaster, Eccles, Finsbury, Fleetwood, Glasgow, Hackney, Hawick, Ilford, Lichfield, Northampton, Plymouth, Reigate, Rothesay, St. Pancras, Sheffield, Stanley, Sutton, Torquay, West Ham, Wolverhampton, Wrexham, Chesterfield, Leeds, Pudsey, Burnley, Ashton Under Lyne, Darwen, Hyde, Darlington, Morcambe and Heysham and Mexborough, Sidcup, Ashton-under-Lyne, Andover and Saltburn.
Lighting: Installations


Modified Street Lighting in Kendal p46
Description of the installation in Kendal.
Lighting: Installations


GEC Lighting Fittings p46
Pictures of various fittings complying with ARP standards.
Lighting: ARP, Lighting: Luminaires


Adverts: British Commercial Gas Association, APLE, Public Lighting, William Sugg And Co., Ltd., Siemens Electric Lamps And Supplies Ltd., Metropolitan Vickers Electrical Co. Ltd, Standard Telephones And Cables Ltd., The British Thomson-Houston Co. Ltd., Concrete Utilities Co., Ltd., British Tungsram Radio Works, Ltd, Hobbs, Offen And Co. Ltd., British, Foreign And Colonial Automatic Light Controlling Co., Ltd., Foster And Pullen Ltd., Automatic Telephone And Electrical Co., Ltd. and The General Electric Co., Ltd