June 1, 1883.] 



SCIENCE. 



483 



energy exaetl3r equal to that we have just 

 analyzed iu the gas-burner, and notice how 

 totall3' different it is in iiind. The upper 

 curve shows the distribution of such a small 

 sample of the sun's radiation as shall be 

 exactlj' equal to that from the argand burner. 

 Of 1,000 parts of sun energy, 340 appear as 

 light, and 660 as dark heat, if we take the 

 dividing-line between light and darkness at 

 the same point (wave-length 0.0007 mm.) 

 in each curve. If we look at the quality' of 

 the light, the difference is enhanced. The 



Similar curves obtained for the electric light 

 would be interesting, but I have not under- 

 taken them. 



We are accustomed to indicator and other 

 diagrams in the use of the steam-engine, show- 

 ing us how our energy is being generated ; but 

 it is singular that so little has been done in the 

 present direction in showing us with what 

 econom}^ it is being emplo3-ed. I think inter- 

 est attaches to these curves from a purely 

 scientific stand-point, and they were made with 

 no ulterior purpose. Yet in looking at them 



DlstrihuCiOTi. of raxiiunt ervei-gj in the spectru/u of an. aiyarui gcus-Oiirner. 



sun-curve attains its greatest height in the 

 yeUow, which here means that the energy is 

 not only most eflScient in making us see (that 

 is, is most available as light), but that of 

 this light the energj' is again most effective 

 in a part to which the ej'e is most sensitive, 

 while, of the small amount of energy em- 

 ployed by the gas in making us see at all, 

 most (as shown by the height of the curve 

 in the dark red) is spent in raj^s to which the 

 eye is not sensitive, and which give the gas 

 its well-known inferiority in qualit}^ (of color) 

 to sunlight, even where the quantity is the 

 same. 



I can but be so impressed with their utilita- 

 rian applications that I will ask leave to 

 make a remark in conclusion with reference 

 to this. 



The gas-plant of this country is said to be 

 some $30,000,000 ; and (except so far as it is 

 used in heating) it appears from what has just 

 been said, that it is mostly wasted as com- 

 pared with the results possiblj' attainable, and 

 in the sense that it does not realize one one- 

 hundredth of what an ideally perfect lighting- 

 agent might get from the coal now used. 

 Though this ideal light will never be fully 

 realized, it is undoubtedly possible to do what 



