Publisher's Synopsis
Excerpt from Practical Illumination
Before going into the details of the various points involved in artificial lighting, a short statement of some of the principal reasons why present attempts at efficient illumination are so often found faulty will aid to an understanding of the subject.
One reason why much light is wasted is that frequently too much of the light goes in directions where it is not needed and too little in directions where it is needed. If light coming from a lamp were a tangible thing, as, for example, water coming from a hose, failure to direct it where needed would be more apparent than it is. No one would think of trying to wash windows, ?ush off pavements or do similar work calling for a concentrated stream of water with a hose fitted with a lawn sprinkler which throws a gentle spray in all directions. Nor would one think of using a nozzle giving a powerful stream on a ?ower bed or a soft, newly-made lawn. The light thrown in different directions around a lamp can be modified with globes and re?ectors just as the direction and character of a stream of water issuing from a hose can be modified bv the nozzle. The important point is to pick the right kind of nozzle and the right kind of re?ector or globe for the particular work in hand. Although a certain amount of light on ceilings and walls is a good thing, it is quite likely to be the case that a much larger proportion of the total light goes in those directions than is at all necessary, while a smaller proportion than is necessary is thrown in places where it can be utilized. On the other hand, there are cases where the reverse of this is true.
It is of first importance to know what effects various re?ectors, shades and globes will produce. Much attention is therefore given to this in following chapters.
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