Some Notes On Lighting
( Originally Published 1920 )
A STUDY of ceilings naturally leads us to particular consideration of illumination. In the Orient, where sunray glare and heat gave special importance to the problem of lighting interiors in the daytime, it was early recognised that convenience and aesthetics demanded that illumination should come from above. We have seen how they managed this by placing partially obstructed windows high up in walls, and by piercing roofs or ceilings with oblique slits. They adhered to the same principle in artificial lighting, using hanging devices supporting tiny oil lamps.
Both the Semitic races and the Egyptians appear to have used the tree form of support, or candelabra. With the Greeks and Romans, the torch, or tall stand supporting an oil lamp, prevailed, although they, too, knew and used the suspended oil lamp.
Hanging candelabra, or chandeliers, came into use in Europe towards the end of the ninth century, by way of the church, gradually spreading to palace and castle. But the standard candelabra and wall bracket largely prevailed, the latter being an elaboration of primitive resinous torch sup-ports. These consisted of wall sockets, and above them a projecting bar, terminating in a ring : the torch was placed through the ring, its base resting in a socket ; consequently being` inclined outwards. Nevertheless the chandelier was in great request, first being of iron or brass, then of silver, followed by carved wood covered with gilt gesso duro, cut glass, bringing us down to the gasolier and the electrolier. It must be confessed that unless carefully designed, these do not harmonise with Renaissance style, especially, when the decoration includes miniature paintings or high relief figure modelling. They are always out of place pendant from pictorial ceilings, for then the incongruity is too manifest, often rather horribly so. As to this, we will refer the patient student to the old Verrio genre ceiling in the Ballroom at Windsor. The ordinary gasolier and electrolier are not very good distributors of light, indeed, though giving greater volume, they afford an inferior diffusion to that of the old chandelier, with its numerous light points, the flames, moreover, reflected from metal surfaces. In this connection, the cut glass lustre is an admirable contrivance, well designed ; being obviously an illuminating contrivance it harmonises with most styles of decoration, while the very large number of facets act as prisms, collecting and reflecting light in so many directions as to give a satisfactory degree of diffusion.
With the comparatively low plaster ceilings of the Tudor and Jacobean periods, the sconces or wall brackets for candles produced very good results, as the light was reflected from the white or buff surface, and as the brilliancy of any one point was low, no great inconvenience would be felt from the light source being on a level with the normal range of vision. But the intense brilliancy produced from gas jets (especially from incandescent mantles) and from electric lamps makes them very undesirable for direct light within the ordinary plane of vision. Moreover, the gas flame or incandescent burner and electric bulb do not lend themselves to decorative blending with many styles, while the unshaded lamps produce too great a contrast of light and shade. Therefore some form of screening the actual source of light is necessary. This may be attained by the use of ground glass globes, or those made on the holophote principleŚwith ribbed surface, by which diffusion is secured ; or by the use of shades. Any of these can be designed to harmonise with other decorations.
The use of lamp glass with ribs of different sizes and angles, permitting of the deflection of light rays as desired, and of inverted shades, suggested the indirect method of illumination. The most common type is an inverted bowl pendant from the ceiling, the lights being placed above, and so concealed by the bowl. The result is that the light is reflected on the ceiling and deflected therefrom to walls and floor, which gives a great measure of diffusion.
The bowls may be of metal or other opaque substance, with the concave portion polished to act as a reflector ; or we may have semi-transparent substances like ground or ribbed glass, opaline or kindred materials. The latest innovation is a reversion to a very old plan to secure softened. light, translucent alabaster being employed for the bowls. It is quite apparent that such pendant globes may be designed to suit any style of ceiling, and placed so as to add to and not detract from the decorative effect.
Another form of indirect lighting is to utilise the new tubular electric lamps, either with filaments, or some form of gas like the mercury vapour lamp, or the Moore carbonic acid lamp, these being concealed in the cornice, and the light reflected on the ceiling.
From indirect lighting the next step was to diffused illumination, the idea being to reproduce daylight effects. The usual way of attaining this end is to use very flat, finely ground, glass bowls, covered in at top, and enclosing either gas or electric lights. A large measure of diffusion is thus secured. Greater effect is produced if concave ground glass bowls are placed in the ceiling itself, the light source being behind. We then have a number of moons diffusing light from overhead. These can be easily adjusted to suit most decorations, being placed in coffers, at intersection of beams, or made the centres of flowers or some geometric pattern.
Diffused light of this kind is well-adapted for lighting corridors, large entrance halls, picture galleries and museums. But if the illumination is intense enough to satisfy modern demands, it is very fatiguing to the eyesight, producing eyestrain from the very same cause as snow-blindness, or the weariness that comes over those who have to suffer the 'glare from a tropical or semi-tropical sun coming from above and reflecting from white level stretches of sand. The eye is attacked from all sides and is exhausted. The better way is to be content with indirect light ; or very soft diffused light supplemented by a few well-placed lights. For instance, let us consider a ceiling divided up into panels by means of beams or heavy mouldings. Let the low concave glass light diffusers be placed in the centre of the panels or coffers, and then let a few inverted gas mantle burners or electric lamps of low candle power hang from the intersections of leaves or mouldings. These will provide moderate points of attraction, and just sufficient variation in distribution to relieve the eye. Another plan is to have soft diffused illumination from the ceiling supplemented by a standard or two used as reading or working lamps, but concealing the actual source of light, having regard to their being in the direct line of vision.
It is to be hoped that from these few notes it will be gathered that modern improvements in illumination should be studied from the aesthetic point of view, for it will then be seen that they can be enlisted as aids to the decorative treatment of interiors.