The Press., 1912-12-11
WAVES OF LIGHT,
They Vary In Length and on That
 Account Vary In Color.
OUR SUNLIGHT IS PURE WHITE

The Arc Light 10 Its Closest Rival,
 With Its 10000 Candle Power Per
 Inoh-Ths Way Human Being With
 X Ray Eyes Would Be Handicapped.
 Light travels at a speed of 1S0,000 miles a second. The source of all light, except the light from firefies and their kin, is a substance raised to n tempera- ture sufficient to set up waves in the surrounding ether. Light waves vary in length between 1-334O0 and 1-050O0 of an inch, the first being extreme red and the second being extreme violet Rays of white light have q length of 1-45OO0 of an inch. The sun is n great mass of white hot matter.
 In an arc lamp 1t is the white hot particles of carbon floating between the two electrodes which produce light. In the incandescent lamp 1t is the hair pin filament inside the glass globe which, when heated by electricity, gives off light waves. Tn gas md oil lamps light Is produced by the heated particles of carbon in the flame above the wick or mantle. The eye can stand without tiring a brilliancy of about five candlepower per square inch of surface. The ordinary candle flame gives from two to three candle power per square inch, while the sun at zenith gives OoO,Ooo candlepower per square inch. The arc light ranks next to sunlight, with 10000 candlepower per inch and the best tungsten filament | incandescents give about 1000 candle power.
 The prism shows us that white light Is composed of q happy blend of all the cOlors of the spectrum. The sun gives the only pure white light, with the arc lamp close second, and the metal flament incandescents taking third place. Sky light, such as comes from the north on q clear day, is bluish white. Gas mantles give n grcenish light, open flame yellow light and kerosene m orange light.
 Tn the dark no color exists. The color of light depends upon the length of the waves. The light source which we know as red gives off only waves of length to produce that particular color. A body appears red because It's surface absOrbs all the other waves and reflects the red waves back Into the eye. A thing looks black when lt is capable of absorbing all the colors at once. .' ...
 Light rays, being, in active motion, xvh wi ra- sistanee in their path. This is why black clothing Is warmer in summer than white clothing, the resistance be. Ing on the surface of the white cloth Ing and nearer the skin when we wear black. '' '7
 The eyes have only certain range, weak enough at best. As we all know, there are times whennall appears black to. us and yet animals can see. The trouble Is the, faint light rays move too slowly to be registered on the hu- man retina, The x ray has proved be yond a doubt that there are light rays which move too fast for human eyes | to register This light penetrates books, wood, paper and even human flesh!
 With the x rays to assist our eyes we can see the bones ip our arm with out bothering to remove our shirt. But man with x ray eyes would be sadly handicapped In this world, for he could see nothing but solids, such as carths and metals, and would be unable to see a board fence at all. To us all is darkness beyond what our eyes will register.
 Light rays themselves are invisible When they move thUaush SAe ether alone our eyes cannot Sce tAena. con seQnentlyl all is total darkness fSSat when they mcet with the resistance o5 our atmosphere, pCoaaciue boat. they register on the rctiua, and, behold we can SttN AS inc atmosphere thinS rapidly as we go upward, so, in pro portion. the air re$i$tance diminishes. and consequently the heat of tho sun seems to grow less. This explains why the tops of very high mountains are al WAYS covered with Snow.--New York Press.