C02 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



because at a distance below, equal to the length of a wave, the motion is 

 only one five hundred and thirty-fifths of that at the surface. 



The size of the wave depends, therefore, upon the force of the wind and 

 the depth of the sea. The largest on the Atlantic observed by Captain 

 Scoresby were 550 feet long and 30 feet high. 



Air-Waves. 



The air, however, is not confined like the sea, which has only an upward 

 and downward motion, except near the shore, where the force it contains 

 would escape. But the whole mass of air, moving as wind, has also a 

 vibratory or wave-motion producing sound. If the distant bell we hear is 

 tuned to middle C of the musical scale, according to the new French stand- 

 ard, and the temperature is at sixteen degrees centigrade, its sound is 

 produced by air-waves vibrating' — not undulating — at the rate of 522 per 

 second, each of which is about 2-15 feet in length. The lowest octave of 

 this note which could be* heard would, according to Savart, be the result 

 of 16.31 waves per second, each about 68.8 feet long, and the highest 

 octave by waves moving at the rate of 33,408 per second, each 0.492 of a 

 foot in length. 



jEth- Waves. 



Turning now to the light produced by the fifteen Argand lamps, we be- 

 hold still more wonderful wave phenomena. The all-pervading seth is, for 

 miles around, thrown into undulations moving at an average rate of 582 

 million of million per second, having an average length slightly exceeding 

 twenty-one millionths of an inch. These numbers, determined by r(>poated 

 experiment, appal us, and we turn to that branch of the subject where 

 results are more palpable. 



The Chemistry of Flame. 



All the phenomena attending the artificial production of light are not yet 

 fully understood. Light is only one of the effects of the burning of hydro- 

 carbons in the gaseous state. Tlie solid candle and the liquid contents of 

 the lamp must be volatilized, and brought into the same expanded state as 

 ordinary illuminating gas before they can be burned. This condition is 

 attained, in the case of the candle, by the heat of the flame; the liquid 

 wax or tallow, b3' capillary attraction, is carried along the wick to the 

 point where it is turned to gas. Yet light does not emanate from gases. 

 Draper found that while gases heated to over 1,100 degrees centigrade do 

 not give light, all the solids subjected began to be luminous at about 510 

 degrees C. and they display the several colors of the prism, and finally emit 

 white light. 



In the process of burning illuminating gas, the hydrogen is first com- 

 bined with the oxygen of the air, and the solid particles of carbon, thus 

 deserted by the hydrogen and exposed to the heat generated b}' the burn- 

 ing gases, become incandescent, and afterwards unite with oxygen forming 

 carbonic acid gas. 



It is, however, true that when the carbon is consumed at the same time 

 with the hydrogen, no light is evolved; such condition exists when the 



