42 PHILlPS TECHNICAL REVIEW Vol. 5, No. 2

INTERESTING LIGHTING EFFECTS OF THELIEGE WATER EXPOSITION

by L. C. KALFF. 628.974

The Liége water exposItIOn, which was openedin 1939, and which was planned primarily to callattention to this busy industry centre of easternBelgium, was unfortunately compelled by theoutbreak of the war to close its gates prematurely.It had already proved a great success, and theattendance and interest of the public were verygreat. This was undoubtedly due in some part tothe logical arrangement which avoided the con-fusing and fatiguing effect of a too comprehensiveworld exposition, and to the aesthetically successfulbuilding construction under the direction of theyoung architect F aIis e.In planning this exposition the importance of

keeping the design and execution as much as pos-sible under a unified direction was immediatelyunderstood. A fruitful and interesting coöperationwith the Philips consulting bureau for illuminationresulted from this conviction.The grounds of the exposition were laid out on a

very generous scale with two permanent boulevards40 m wide along the banks of the Meuse which isabout 180 m wide at this point. The lighting ele-ments had to be in good proportion to these broad

open spaces and to the high and massive buildingsof the exposition. It is to the credit of the architectthat he did not hesitate to accept the unusuallylarge dimensions to which this consideration ofproportion led.

In the first place there were the wide boulevardsalong the Meuse, along which were erected stan-dards 13 m high at distances of 50 m, each bearingsix lamps of 300 dlm, which together gave a veryuniform illumination of 40 lux over a width of 40 m.The six simple enamelled reflectors in which thelamps were fixed housed in a dome-shaped capmade of eternite (fig. 1) in such a way that anyone looking along the boulevard was not disturbedby glaring points of light (seefig.2). The standardswere manufactured by the Liége steel industryfrom steel plates bent into circular form andwelded. The result was beautifully slender smoothcolumns which will form part of the permanentlighting system in the future. One of the leadingideas in planning the exposition was the desirabilityof being able to use the exposition material forpractical purposes later on, as well as that of usingas far as possible materials (rolled and profile steel,

FEBRUARY 1940 TIlE LIEGE WATER EXPOSITION 43

=

Fig. 1. Construction of tbc standards for lighting the boulevardsalong the Meuse. Six 300 dIm lamps are arranged under aneternite dome.

eternite, plates of wood fibre, glass) which couldbe supplied by the industries in the neighbourhoodof Liége.

In order to break the monotony of the maintraffic highways a strip of grass was sown alongthe middle, and lower, more decorative lightingornaments were placed between the high ones.These lower lamps also provided an extra illumin-ation of the flower beds surrounding them (fig. 2).The ornaments consisted of fivem standards crownedby a double cone. The upper cone contained a loudspeaker and the lower one three milk-glass globeseach containing a 150 dlm lamp. Three archescontaining a total of 54 small Argenta lamps shedmost of their light upon the flowers. Three stripsof netting, painted white, were stretched along thestandards and were illuminated from below by three"Cornalux" mirror lamps of 100 watts (for theinstallation of these lamps see fig. 3). As may beseen in fig. 2, these simple motives gave a verypleasing effect, thanks to their correct proportions.

The imposing square directly behind the mainentrance, of which the title page photograph givessome impression, was transformed into a watergarden. It contained decorative flower mosaics,small fountains, statues and paths. The paths werepaved with heavy plates of Cast glass lighted from

Fig.2. Between the st adards for t he boulevard lighting, standthe light ornaments for illuminating the flower beds. Theyare five m high and bear a loud speaker and three milkglassglobes each with a 150 dIm lamp. The strips of netting arelighted with "Cornalux" lamps.

below. In contrast with this effect were fourenormous standards 20 m high of the same con-struction as the 13 m standards described above.In this case the eternite cap contained three mer-cury lamps type NO 2 000 with three ordinaryelectric lamps of 1.500 watts, which together gavea light source of 13 500 dlm. The centre of thesquare was in this way very weU lighted with anintensity of 60 lux (fig. 4).

A

Fig. 3. Construction of one of the ornaments of fig. 2. Thedetail sketch A shows the position of one of the three "Cro-nalux" lamps illuminating the netting.

44 PHILIPS TECHNICAL REVIEW Vol. 5, No. 2

The flower mosaic (fig. 5) consisted of squareflower beds alternating checker-board fashion withsquare pools of water. At the centre of each poolwas a fountain about two m high, which was illum-inated at night by means of four" Altrilux" lamps.These are lamps of a special shape and construction(fig. 6) intended to be used under water. The bulbis silvered on the inside over half its surface so that

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Fig. 6. Construction and assembly of the "Altrilux" under-water lamps.

Fig. 4. The great square behind the entrance is illuminatedby four 20 m high standards of construction similar to thatin fig. 1. The cap on each standard in this case however con-tains three mercury lamps, type NO 2000, and three 1500 wattelectric lamps, which together give a light flux of 13 500 dlrn.

a concentrated beam is obtained and a specialwater-tight reflector is unnecessary. The lampsare cemented into a small cylinder which alsocontains the lamp socket. The cylinder must befirmly anchored to the bottom of the pool, because,due to the large volume of the lamp, it has a fairlygreat floating power (± 2 kg). The lamps are placedas n~ar as possible to the surface of the water in

Fig. 5. The flower mosaic of the great square was formed by a checker-board of flower bedsand pools. The two m high fountain in each poolwas illuminated from below hy four "AI-trilux" under-water lamps. Each flower bed receives itsIight from four "Philiflor" reflectors.

FEBRUARY 1940 THE LIEGE WATER EXPOSITION 4.5

order to limit the loss of light, but there must be alayer of water of a certain thickness above thelamp since it would otherwise be broken by thefalling water from the fountain. Moreover the highcalcium and phosphate content of the water inLiége was a disturbing factor. Within a few daysa layer of scale formed on the lamp which was verydifficult to remove and which caused considerableloss of light. For that reason the originally plannedpower of these under-water lamps was doubled

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Fig. 7. Ground plan and vertical cross section of a squareflower hed and pool.

Each square flower bed was illuminated with four"Philiflor" reflectors with 125 dIm lamps (fig. 7).In the centre of the great square, as may be seen

in the title photograph, were two pools and sixlarge statues. These pools were bordered by asinuous luminous line formed by a row of 40 dlmlamps in an eternite light cove (fig. 8). The lampsthemselves were invisible but their reflection couldalways be seen in the water which was kept incontinual motion by the play of the fountains. Atotal of 1800 lamps were used in this detail. Twelve

Fig. 8. Construction of the light coves along the pools in themain square. _The reflection of the 40 dlm lamps placedin the cove is visible in the water.

Fig. 9. Illumination of the groups of statuary bordering thepools. The sinuous luminous outlining of the pools by meansof the light cove can also be seen.

mirror reflectors type FLD with 250 watt search-light lamps illuminated the groups of statuary(fig. 9).Another interesting part of the illumination of

the exposition was formed by the decorations alongthe 180 m wide Meuse. This broad strip of waterhad to be incorporated into the illumination so thatthe exposition should not be cut in two in theevening by the dark strip of water. It is nearly im-possible to render a stagnant water surface visiblewith light sources of limited dimensions, since thewater reflects only specularly. Due to the currenthowever the water of the Meuse is in continualmotion. Just as the image of the moon is drawnout into a long path of light by a rippling watersurface, in the same way a long row of lamps alongthe bank should transform the whole stream intoa brilliant glittering surface for an observer on theopposite bank. Experiments were found to confirmthis expectation. Therefore eternite light coves

Fig. ID. Construction of the eternite light coves along thebanks of the Meuse. The row of 40 dIm lamps in the covesilluminates the stone embankment of tbc river, and by reflec-tion in the rippling water makes the whole surface of thewater visible to an observer on the opposite bank.

46 PHILlPS TECHNICAL REVIEW Vol. 5, No. 2

Fig. ll. The effect of the illumination along thc hanks of the Meuse.

(jig. 10) 31/2 km long were set up on both sides ofthe river, containing 40 dIm lamps at half meterintervals. These lamps illuminated the embank-ment and together with the lighted buildings werereflected in the rippling surface of thewater (jig. 11).It would have been possible to construct

numerous illuminated fountains III theriver, but it is necessary to keep in mindthat the huge dimensions of the watersurface would have rendered any ordinaryfountain insignificant. It was thereforedecided to build a single simple illuminatedfountain (jig. 12). on a pontoon, but.of dimensions in scale with those of theriver. The fountain had a jet which couldreach 200 m, for which pumps with motorsof 1 200 h.p. were necessary. The illumin-ation of this floating fountain was by meansof yellow and white light by 64 reflectorswith three kW lamps, which were mountedwater-tight in the pontoon. Fig. 12 showsanother remarkable lighting effect. It wasthe desire of the architect that there shouldalso be a lighted boundary in an upwarddirection. For this purpose two flat beamsof blueish-white mercury light were pro-jected at a height of 100 m from the top ofthe mast of the cable railway over the ex-position. Due to the scattering by dustparticles and mists these fan-shaped beamswere visible from below and formed in thisway a kind of ceiling over the exposition

grounds. The beams were obtained by means ofthe apparatus shown in jig. 13. Two water-cooledsuper high pressure mercury lamps with a totallight flux of 24 000 dlm were mounted in parabolic

Fig. 12. Large fountain in the middle of the Meuse. After dark thefountain is illuminated with yellow and white light.

FEBRUARY 194D THE LIEGE WATER EXPOSITION 47

Fig .•13. By means of two searchlights with a totallight flux of 24 000 dim two broad flatbeams of light were projected as a "ceiling" over the exposition.

cylindrical mirrors. The lamps, type SP 2 000,consume only 2.3 kW for a light flux of 12000 dlm.The beams obtained are very flat and wide(2° in height and 120° in a horizontal direction),and are otherwise quite similar to the beams usedto illuminate landing fields in aerodromes (Philipstecbn. Rev. 4, 93, 1939).

Tbe importance of illumination in tbe laying

out of tbe exposition is most clearly seen from thefact that a total of 12 000 kW was installed forligbting and 16000 kW for power. In the middleof July the current consumption was 35000 k.w.h.per day. Before the premature closing a consump-tion of 50000 k.w.h. per day was anticipated forthe month of September.

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