Green reflects about 18%, blue 12%, so you can see here what to do with certain rooms that should be dimmer or brighter. In the same way shades of globes enhance or detract in reflection capacity. Clear glass absorbs about 5-12% of light and cobalt blue about 95%, so here you see if you have a lamp absorbing 95% of light--that you will need more lamps than one absorbing but 5%! Think on these things. LIGHT MEASUREMENTS The foot candle is the unit of light measurement. A standard candle has been decided upon and all lighting calculated on this basis. We say we have 16 candle power lamp that it means it gives light of 16 of these standard candles. From a 60 watt lamp the candle power obtained from a tungsten is 56 candle power. A saving in money is had if the tungsten though more expensive is used. COST OF LIGHT, ELECTRIC The amount of electricity taken by a lamp is measured in watts-- Watts ÷ 1000 equals Kilowatts Kilowatts × hours equals Kilowatt hours Kilowatt hours × rate equals cost. (See Chapter I on Electricity.) Economy is quite possible here as in burning oil or any thing else. If your lights are well placed, you need less light, if they have not too absorbent globes you will also need to use less light, if you have proper wall tints, etc. You often need fewer lamps. One good lamp in the right place saves two or three wrongly placed. The Tungsten filaments burn brighter and more cheaply than the old filament of carbon. There is a saving of electricity somewhere around 50% in the use of new filament. THE INCANDESCENT LIGHT That brings us to the story of the incandescent lamp-- Incandescent means to glow with heat--In short the incandescent light is one which employs a globe in which the air has been exhausted and in which a vacuum exists. Before the air has been exhausted a filament of metal has been affixed through which the current of electricity is passed. In the resistance of this current the filament glows and gives the light that you use. Don’t take any lamp you can get. Ask for the number of candle power or watts you want. The lamps to-day are more popularly sold according to watts rather than candle power. INDIRECT AND DIRECT LIGHTING Of course there is a loss every time the light is reflected through a diffusing medium. In correct direct lighting most of the light is only reflected once before using point. In indirect lighting it has one more reflection (at ceiling) causing a loss hardly much less than 25% and maybe more. The diffusing bowls throw a large part of the light--in semi-direct lighting--where there is a similar loss and the part of the light which goes through the bowl is considerably reduced by absorption. Naturally direct lighting is most efficient. Yet lighting is a matter of diffusion of light and often the indirect system gives not only more joy but better illumination with no greater consumption of power than direct lighting.