728 VERHOEFF AND BELL. 



eye, the energy in the discharge may be reckoned as one or perhaps 

 several thousand times that of the short circuit discussed in connec- 

 tion with Knapp's case. With a nearby discharge occurring say 

 within 10 or 20 meters, the quantity of energy received by the eye 

 would be amply great to account for even severer results than those 

 noted by Knapp (loc. cit.). 



Working back from our experiments with the bare magnetite lamp 

 carrying about 500 watts in the arc, it again appears that the quantity 

 of energy assumed by Sir Oliver Lodge is more than sufficient to ac- 

 count for the results of a nearby discharge. It therefore must be 

 admitted that the direct action of lightning in producing both abiotic 

 and thermic lesions in the eye as in the cases of Le Roux et Renaud 

 and of Oliver is well within the bounds of possibility although requiring 

 very unusual proximity to a powerful discharge which may well have 

 been the case in these instances. The extreme rarity of such clinical 

 conditions is perhaps ascribable to the few instances in which there is 

 close proximity to the stroke combined with free exposure of the eyes 

 without the patient being actually involved in the shock. One must 

 consider therefore that lesions produced directly by the radiating 

 energy of a lightning discharge are extremely unusual and unlikely 

 to occur, although well within the range of possibility, as the cases 

 here referred to show. 



Possible Specific Action of Infra Red Radiation. 



As we have already stated, there was no segregation of various 

 radiations in our experiments on thermic effects except in so far as 

 abiotic radiations were cut off by certain screens. So far as all indi- 

 cations go the effect of all other radiation than the abiotic is chiefly 

 chargeable to thermic energy without respect to wave length. As 

 already explained different sources present totally different distribu- 

 tions of energy with respect to wave length, the lower the temperature 

 the greater being the proportion of the so-called infra-red rays. In 

 the case of the quartz mercury arc and the magnetite arc with which 

 we chiefly worked, the spectra are essentially discontinuous and hence 

 do not obey Planck's law, so that there is no definite relation between 

 the temperature and the wave length of maximum radiation. 



The total energy spectrum of each of these sources, however, is 

 exceedingly complex. Of the total energy spent in the arc a certain 

 proportion goes to maintain the characteristic linear spectra, a cer- 



