The incandescent light has now disclosed its adaptability beyond any other light for exposition purposes. This broad statement is justified by the results finally attained at the present Pan-American Exposition.
The writer, having been identified with the first gas and electrically lighted expositions open at night, and most all of the prominent ones to date, either as designer and constructor, or as consulting engineer, has accumulated a complete library of data on this subject, from which the following is reviewed.
The history of the evolution of exposition lighting is a history of the many vagaries of practice that have finally led up to the use of the incandescent lamp as exemplified at the Trans-Mississippi and International Exposition in 1898, at Omaha, and on a larger scale at the Pan-American Exposition of today. It may not be amiss to refer briefly to the decorative illumination which antedates the time when electricity made the extensive illumination of large expositions possible.
The first festive illumination was practiced by the Chinese, who enclosed lights with fancy paper shades or lanterns. Architectural accentuation or outlining for festive occasions was originally done by candles or lanterns placed on windowsills or on the interior of windows. Candles were followed by gas jets, placed close together to reignite when extinguished by air currents, or protected by colored globes. Tea-store lighting in vertical lines by gas with enclosing glass globes (mostly in color) and also accentuation, festooning and outlining, succeeded the early illuminations by candles and lanterns.
One of the first building exteriors to be decoratively lighted was the Turkish Pavilion at Manhattan Beach, L. I., in 1881, there being in use about 200 small gas jets enclosed in colored globes for the double purpose of protecting the jets against air currents , and also for the effect produced. The jets were electrically ignited. The lights were placed on the ribs of the dome of the pavilion about one foot apart. This pavilion had been at the Centennial Exposition in 1876, and was re-erected at Manhattan Beach in 1880. The first decorative outdoor electric illumination was on Elbridge T. Gerry's yacht Electra, in 1883, which had 200 incandescent lamps hung in festoons between the masts, bowsprit and taffrail, outlining the upper rigging. These were placed about two feet apart, making a pleasing effect, and of a form now often seen on an elaborate scale on naval and marine festive occasions. The Paris Electrical Exposition of 1881 had electric lighting, principally by arcs, and confined to the lighting of the building interior and several large incandescent-lamp exhibits. In the United States the notable expositions about that period were two at Boston, one of which, the Mechanics' Fair, had 1,500 incandescent lights, which constituted, for that period, the largest plant in the world.
This was interior lighting. Following this, there was nothing of moment until the Vienna Exposition of 1883, which had mixed lighting. This same year comprehensive electric-light plant for an exposition -was made by the installation at the Southern Exposition at Louisville, Ky., of 7,000 16-candle-power incandescent lamps. The floor space lighted was 14 acres. This was the first exposition entirely lighted by incandescent light, and also the first to bring the light up gradually from nothing to full candlepower. This lighting was so satisfactory that it was reinstalled in 1884, another exposition being held that year. It may be appreciated that in that instance there were 14 generators running in parallel, serving 19 feeders. All the heavier lines were of bare copper.
In 1884 the Electrical Exposition under the auspices of the Franklin Institute took place at Philadelphia. At this exposition the commercial rivalry between competing companies led to a mixture of light that bordered on excessive display, with one exception, which was the Pennsylvania railroad station, which was lighted from the exposition by incandescent lights of 16 candlepower on a commercial basis to demonstrate the sufficiency and economy of incandescent illumination. Various expositions about this time, such as Cincinnati, Milwaukee and others; had partial electric-light illumination, principally by art galleries. In 1884 the St. Louis Exposition was completed as a permanent annual exposition, which has been kept up until the present. Its floor space is some five or more acres, and it contains a theater and one of the largest music halls in this country. The only electric company willing to undertake the lighting of this large building proposed to do it with the incandescent lamp. It was awarded the contract for the entire building, requiring over 5,000 lamps. This is a notable installation, from the fact that it was the first to have knife switches introduced. Many of these original switches are still in use. This was the first to have the wiring system of control and distribution known familiarly and in use the world over as the cabinet system. The feeder lines were bare copper placed in capped molding, the wire coverers at that time being unable to cover heavy copper. This installation was until quite recently still intact. In a measure none of these expositions could be considered of magnitude. The World's Industrial and Cotton Exposition of New Orleans, in 1884 and 1885, continued the pace set by the Louisville Exposition by lighting all the interiors for visitors at night, and as much of the grounds as required for traffic. This being an international exposition, comprised many buildings, one of which (the largest yet erected) covered 34 acres, another 18, and in all 61 acres was under cover, or the same floor space as the Centennial of 1876. This lighting was under contract under two systems, one of arc for general illumination, the other by 20,000 16-candlepower incandescents, placed in the most desirable sections, such as the mammoth music hall and art galleries. At this exposition the lights were under control from zero to full candle-power, as they were at Louisville in 1883. Nothing in the way of expositions demanding extensive illumination took place from this until the Paris Exposition of 1889. This being an extensive international exposition, demanded the careful consideration of the expediency of illuminating all the building interiors. It was finally decided, owing to the great cost and uncertainty of securing service at that time, and the thief hazard, to light up only one-fifth of the buildings, closing the rest at night, the large Machinery hall or Main building, being the only one of the main buildings lighted. This was due largely to the electrical apparatus in operation in that building and the local display of light. The ground lighting was principally done with gas, especially the decorative lighting. A few Jablochhoff candles were shown as exhibits. A few incandescent lights were placed outside on the grounds, with very pleasing effect.
This brings us to the World's Columbian Exposition of 1893 at Chicago, which had over twice the area of any exposition so far held, and was the first to introduce decorative illumination on its main buildings in a comprehensive way by outlining and accentuating the cornices of the buildings and embankments of the Court of Honor, there being some 8,200 incandescent lights of 10 candlepower placed for this purpose. The Court of Honor, as well as most of the grounds, was lighted by arc lights; over 1,200 specially designed cast-iron posts were used. These posts were hollow to admit of the concealment of the electric conductors. The cost of these posts, with their setting, was nearly $100,000. This was the first exposition to place the electrical conductors underground. This, was required to prevent interfering with the view in the main vistas, and for that time was a great undertaking. The success of undergrounding at this exposition has enforced its adoption at all subsequent expositions in all important vistas. All the main buildings were lighted either for patrol, general illumination, for traffic or more brilliant illumination, such as the Art Gallery, where no less than 22,000 10-candlepower lamps were used. Over one mile of picture-light screens were in use. The total of the lighting at Chicago still maintains the record, there being in service on the grounds 5,687 arc lights. The larger contract for incandescent lighting was for 61,000 lamps. This, with other contracts, made over 100,000 16-candle-power incandescent lights, or a total of more than 1,600,000 candlepower in incandescent light, and 11,374,000 (nominal) candlepower arc; grand total, 12,974,000. Total inside area lighted by arcs, 4,877,965 square feet; area of buildings built by the exposition, 6,500,000 square feet; by states, 40,000; foreign, 30,000; concessionaires 1,100,000; total, 7,940,000-a little less than 200 acres.
As early as this exposition the incandescent lighting adopted at Omaha and the Pan-American was proposed for the Court of Honor. Commercial rivalry and lack of support prevented. As the lighting had to be done by a number of contractors, it was feared that with the service that was available, it would not be possible to obtain the desired results, and the original scheme was abandoned. However, the illumination that was finally accomplished, being new, was accepted by the public with favor, and set the pace for subsequent expositions.
In 1894, at the Earl's Court, London, the embankments and decorative lighting of Chicago was repeated on a smaller scale.
The Midwinter Fair held at San Francisco in 1894 had the buildings of the Main Court outlined principally on the cornices with 2,256 incandescent lights. The Tower with flashing incandescent lamps situated in the center of the Main Court as a spectacular feature, had 3,213 incandescent lamps, mostly in color. The grounds of the Main Court were lighted by 96 arc lamps. There was altogether in the Midwinter Fair 9,132 16-candlepower incandescent and 91 arc lamps.
The Cotton States and International Exposition, 1895, had some 5,000 incandescents placed on the exterior of the main buildings. The grounds were lighted with arc lights supported on hollow wooden posts. There were also a few trial lampposts with incandescent lamp clusters. The grounds had 350 arcs.
The Nashville Exposition in 1897 had some 15,000 incandescent lights used in the illumination of the buildings. The central grounds were lighted by arc lights placed on hollow wooden posts bought front the Atlanta Exposition after its close.
At the Trans-Mississippi and International Exposition at Omaha in 1898, the first comprehensive and complete decorative and ground illumination by incandescent lamps was introduced. The Grand Court was entirely lighted by eight and 16-candle-power incandescent lamps. The buildings surrounding the court were of classic design, well adapted to outlining and decorative treatment. There were nearly 21,000 lights of eight and 16 candlepower used for this purpose. To light the grounds of the Grand Court 309 lampposts, with 12 to 20 incandescent lamps on each, were arranged. They were the same hollow posts used at Nashville for arc lights, but cut down and covered with ornamental staff. This Grand Court lighting demonstrated beyond doubt the value of distributed lighting by small incandescent lights of eight and 10 candlepower. In this, all concentrated or intense light was carefully avoided. The success attained in the Omaha lighting was due to the following:
It may be appreciated that any indifference in the operating would have given a dimness or a brightness to the incandescent lamps, either of which would have been apparent as faulty.
Some time after the closing of the Omaha Exposition a writer commented on the illuminative effect as follows: "There was a time when Mr. Edison stood alone as to the decided merits of incandescent over arc lamps for lighting considerable areas, but happily the converts of diffused lighting, when properly executed by competent engineers, are rapidly increasing. Those who remember the old Louisville Exposition of 1883, and the wonders there accomplished by properly distributed incandescent lamps, remember it was predicted that twice the number could not produce the effect desired."
The Omaha illumination earned for the writer a gold medal and diploma, which was the highest award given by the exposition.
A commission was sent by the Paris Exposition of 1900 to investigate the illumination at Omaha in 1898. The Paris Exposition failed to profit by the experience of years, as exemplified at Omaha, and was a distinct step backward as far as illumination was concerned. No uniform scheme of illumination was there adopted. The lighting was a mixture of large and small incandescents, searchlight, projectors, display lighting of the spectacular order, acetylene, Nernst lamp, Welsbach burners, gas and other illuminantsa conglomeration which was entitled to more credit as an exhibition of all known modern forms of lighting, than as a comprehensive scheme of exposition illumination.
Owing to the assumed available and liberal use of Niagara Falls power by the Pan-American Exposition, the electrical expectations were keyed to a phenomenal point. Electricity was to be turned loose in fanciful display and effects, possible, even if desirable, only in imagination. To satisfy this impression and create a satisfactory showing, a superior illumination was planned and installed. The exterior illumination at the Pan-American Exposition includes the largest vistas of any exposition yet attempted. The area looking north from the pylons to the Electric Tower is 1,400,000 square feet (that of the Court of Honor at Chicago being 650,000 square feet). To this 1,400,000 square feet might properly be added the area of the plaza back of the Electric Tower. The main areas are illuminated as far as is practically attainable without severe shadows, and the illumination borders on the brilliant in its effect. To secure the results which are apparent at the Pan-American a scheme of general distribution of illumination by eight-candlepower incandescent lamps entirely is employed. All obtrusive or display lighting in the main vistas has been discouraged as detrimental to the general effect. For this reason no arc lamps are used, and for the same reason high candlepowers are avoided.
It must not be inferred that a good illumination to selected conditions cannot be effected with gas in its various forms, or with arc lights. The advantages, however, in placement alone would recommend the incandescent light above all other sources of light in exposition illuminations.
There is a general increase in the number of lights as one approaches the Electric Tower, which is the climax of the lighting scheme. To secure the best results it is essential in all artificial illumination to get uniform diffusion of light. This cannot be reached by the arrangement of a few extremely brilliant centers about the space to be lighted, because we cannot rival the sun. In fact, such an arrangement acts in itself to defeat the object to be attained. There will be a large portion of light immediately about the sources, while the remainder filters, as it were, through space, growing weaker and weaker as it recedes from the sources in obedience to the unvarying law of inverse squares. Methods of artificial illumination necessarily have some objections, whatever their form. For example, it is often necessary to locate lights in the line of vision. This difficulty must be met by the simple expedient of a more minute subdivision and uniformity of distribution of lamps. As a practical standard, 16 to 20-candlepower lamps should be the largest used. From the structural and decorative standpoint, to secure the best results we must have a lamp so small, as compared with those now in common use, that it gives but little light individually, but is capable of being so grouped, massed or distributed as to produce the desired effects and diffusion without raising any point of space to a brilliancy disagreeable to the eye to rest upon. Until the present time large units of electric light have been depended upon to bring into greater prominence the beauties of surrounding effects. But in thus using the light we fail to avail ourselves of the beauty which is inherent in the light itself when the light is secured from myriads of small units.
The popular impression derived from illustrations sent out, in advance of the Electric Tower illumination, as it was expected to appear, was that it would be translucent and luminous, not unlike the miniature chalk towers with colored-glass windows, lighted from inside, on sale by Italian venders some years ago. If such a method had been possible with the Electric Tower, it would only have resulted in showing, up the skeleton like a radiograph. The effect of translucency and a luminous appearance is, however, produced in an entirely different way, by placing the light so as to secure a uniform illumination, with all desirable points accentuated, thus securing the effect of being luminous by external brilliancy. The light background of the structure has more to do with heightening the brilliant effect than most people who witness it have any idea.
As electricity was the first medium to render comprehensive illumination of the grounds and buildings possible, it was but natural that impossibilities should be expected of it. The history of the Chicago World's Fair is full of vagaries and delusions that by turning on electricity the daylight might be loaded with rainbows and the night flooded with sunshine. Now nature not only forbids such extravagances, but true art, as well as expediency and cost, condemns them. The first duty of an expert in lighting is to emphasize the fact that we can but secure relative effects, the harmony of which will accomplish infinitely more than costly and laborious sensationalism. To an eye that has been fixed on the sun the glow of the incandescent lamp is a sickly yellow, and the beam of the arc a ghastly blue, but coming out of the darkness into a room properly lighted by incandescents, we enjoy at once a feeling of cheerfulness.
In the case of the buildings and grounds, the true principle is to outline and accentuate against the dark background of the night. Thus the imagination is given a chance, and this freedom is pleasant to all intelligent minds. The spectator whose eye is not dazzled moves comfortably about, and the expenditure of electrical energy for a given result in illuminating effect is minimized.
In planning the illumination of the main setting of the Pan-American all spectacular effect was barred. Paris suffered in its last two expositions from the introduction of spectacular fountain and illuminating features in its main court. When such are presented all surrounding illumination must be under control to secure proper contrast. The illumination of the water basins or lakes and fountains therein was first introduced by the writer at the Atlanta Exposition of 1895 by placing 60 incandescent lamps on floats encircling the outer edges of the falling spray from two pyramid fountains in one of the lakes. The next development of this feature was at Omaha in 1898, when about 200 incandescent lights were placed bordering the fountain "Nautilus" and so arranged as to appear as floating on the water and accentuating the edges . of the water figures or splash. This same scheme has been followed on a more elaborate scale at the Pan-American, there being several thousand lights in the main-fountain basin. Designs were also developed for the other basins. These were all designed to serve a double purpose, to light the water issuing from the jets and to illuminate the water in the basin, for ornamental effect. Neither of these has been fully realized, the design of the water figures having been changed from the original plan, which would have given better results, as it harmonized with the water figures, the lights being more scattered and in sinuous lines. As it now exists, it is faulty from being too concentrated. It is composed of rings concentric to each water figure. Between each set of circles is a filling of lamps, intended to represent an arrowhead, but indistinguishable because of the plane of vision. The effect is one of mass without definite arrangement or purpose.
There are important periods in the electrical requirements of an exposition. First, the prospectus outlining the scheme and scope; second, development of plans; third, construction; fourth, operation. The two latter are hard to appreciate, unless one is familiar with all the details, for upon their execution depends success.
The engineer who designs the illumination of an exposition has by no means an easy task. It is not simply a question of circuits, though that is no child's play for a distribution to as many lamps as there are at the Pan-American, nor is it a question of placing a light here and there for immediate use. The expert on illumination must be able to see in the mind's eye the effect he will produce when the exposition is at a stage when the grounds are barren and the architectural features are but little further advanced than in sketches. The prospectus and preliminary report of the lighting of the Pan-American were of necessity prepared from such meager data, and yet substantially all the electric and fountain requirements were anticipated therein.