258 ANNUAL EEPOKT SMITHSONIAN INSTITUTION, 1913. 



action of the violet and ultra-violet rays of light any surface, having 

 a negative charge will leak its charge and ionize the air near it. 

 This may occur in sunlight oxqv such areas as are marked minus in 

 I he figures, and the several minus signs Avould mark or indicate air 

 ionized and negatively electrified over the negatively charged zones. 

 IS"© action would be expected oAer the positive areas or zones. But 

 the zones are not stationary; they are widening very rapidly, so 

 that a positive zone or zones takes the place of negative so far as 

 any location is concerned. This may be expressed by saying that 

 the water surface which at one instant was negative and gave out 

 negative ions under the influence of light would, in an exceedingly 

 small fraction of a second and before those ions could get away from 

 electric contact with such surface, become positive and the free 

 ions would noAv return and neutralize a portion of the positive charge. 

 Thus the negative zones or wave elements would lose part of their 



charge to ionize air, 

 T'\^. Zd. and the positive waves 



/<<p^\ would be weakened by 



^^nn'^x^ such negative leak 



.t\\V)w\ v^^'/- A\\V//// neutralizing them in 



' \^iiliiL, Mi;!n ^\^/^7 part. This action^ 



•♦■ however feeble at each 



wave, would be con- 

 tin u o u s over hun- 

 Hg. 24. . dreds if not thou- 



■~Nx sands of miles, and 



^•^\\\ continuously damp out 



Va\\\\\///, ,\\\//, A//. the widening system 



\A ^^i^' m'^' :i:n:.er^^:^ 



with low frequency 

 waves, as there would be a proportionately less number of oppor- 

 tunities for this neutralization per second. Besides, with the lower 

 frequency there is more time for the separation of the negative ions 

 to such distance from the water surface that they do not combine with 

 the positive charges; being, as it were, better insulated from them or 

 diffused in the air stratum. 



In figure 24 an attempt is made to picture this action of attenua- 

 tion in the presence of light. The negative charges in the air layer, 

 as in figure 23, have no positive charges under them, the encircling 

 lines about the + and — signs indicating combination and neutraliza- 

 tion. 



When the wireless waves reach the receiving antenna, owing to at- 

 tenuation from spreading or loss as above, they are very feeble. The 



