468 



NATURE [j ULY 3, ^3 



makes a good contact, not only with the electric 

 conductor, but also through wet boots or clothes 

 (according as he is standing or sitting), with the 

 ground or sbme other conductor, there is not the 

 smallest chance of death by currents at such low 

 voltages. 



As regards continuous currents of electricity, I have 

 not found records of many fatal accidents at' voltages 

 below 220 volts, but in one case a direct current at 

 only 95 .volts caused death, in another a current at 

 no volts. The minimum number of milliamperes re- 

 quired to kill a human being under conditions favour- 

 able for killing is not known. Weiss calculates that 

 from 70 to 90 milliamperes of an ordinary alternating 

 current would be enough if the current went through 

 the chest and heart; d'Arsonval states that much less 

 than 100 milliamperes suffice to kill. Trotter found 

 that continuous currents up to 35 milliamperes, though 

 almost insupportably painful, were not fatal when 

 passing from the hands to the feet. But when very 

 large industrial currents are forced through the body- 

 by high voltages, we meet with the paradox that", 

 while small currents may kill instantaneously, large 

 currents are much less fatal. For example, the 

 American electrocutions have shown that alternating 

 currents of 5 or 8 amperes may pass for mam- 

 seconds through the body without causing per- 

 manent arrest of the heart" or respiration. In several 

 recorded non-fatal cases of shock by alternat- 

 ing or three-phase currents at 10,000 volts, it is true 

 that no measurements of the amperes passing through 

 the victims were made, but it is reasonable to suppose 

 that they may have amounted to several amperes. 

 It is plain, then, that currents of a fraction of an 

 ampere may cause sudden death bv throwing the 

 ventricles of the heart into fibrillary contraction, 

 though much larger currents of several amperes do 

 not act thus, and so are not fatal. But I do not 

 know of any examples or experiments to show at 

 what point or amperage the transition from small 

 dangerous to large non-dangerous currents takes 

 place. 



So far as one can guess, in the absence of any 

 experimental proof, it seems that a continuous cur- 

 rent must be two or three times as strong as an 

 alternating current, to kill a human being.' So far 

 as sudden death is concerned, electric currents are 

 dangerous to man in proportion to the degree to 

 which they tend to pass through the heart. 



The prognosis in cases of severe electric shock has 

 been very variously estimated. Cunningham (1899), 

 for example, speaks of artificial respiration as "the 

 only, and almost invariably futile, method in vogue in 

 electrical accidents at the' present day," for the resus- 

 citation of_ persons apparently killed bv electric shock. 

 The opposite view is held by Lauffer (1912), who says 

 "there are few cases of electrical accident where the 

 victim cannot be restored from the electrical shock, 

 if appropriate immediate efforts at resuscitation are 

 instituted." 



The treatment — artificial resoiration ■ bv Schafer's 

 or Sylvester's methods— is still that advised bv Priest- 

 ley in 1767. The importance of getting to work with 

 the artificial respiration without a moment's delay 

 has often been emphasised by those who have had 

 much experience of electrical accidents. No less im- 

 portant is the necessity for continuing artificial re- 

 spiration until it is certain that death has occurred; 

 p.nthjntr less than cooling of the body or the onset 

 of rigor mortis should be considered to be evidence 

 of death here. 



Death by Lightning. 



Up to the present time, meteorologists have 

 furnished us with singularly little definite knowledge 

 ^ t O. 2 2'7Q, VOL. Ol] 



about the electrical properties of lightning strokes and 

 the electrical quantities concerned in their production. 

 They may be summed up as very strong electric cur- 

 rents of very brief duration and" very high potential, 

 containing thousands or possibily millions of foot-tons 

 of energy. When human beings are struck, a part 

 at any rate of this energy is converted into heat, 

 producing various bodily lesions in most instances' 

 Death by lightning-stroke is much commoner in most 

 countries than it is in ours. In England and Wales 

 the Registrar-General reported 124 fatal instances of 

 lightning-stroke, 10S in men and sixteen in women, 

 during the ten years 190 1- 10, a yearly average of only 

 12-4 deaths, or 036 per million living. In Hungary the 

 annual death-rate from lightning is said to be sixteen 

 per million living (Milham); in Styria and Carinthia 

 about ten per million, in Prussia 44, in France and 

 in Sweden three, in Belgium two, so far as the im- 

 perfect statistics available go (McAdie and Henryj. 

 In the Unted States of America the annual death- 

 rate per million is high, about ten, in consequence 

 of the frequency of thunderstorms on one hand, and 

 of the lan.e percentage of the inhabitants engaged in 

 outdoor labour on the other ; about 700 or 800 deaths 

 from lightning were estimated to occur in the United 

 States every year by Henry in iqoo, in a population 

 of seventy-six millions. Many more people are struck 

 by lightning than are killed. For example, Jack 

 records an instance in which a church was struck ; 

 300 people were in it, 100 were injured and mostly 

 made unconscious, thirty had to take to their bed^. 

 but only six were killed. Weber sjives an account 

 of ninety-two people struck in Schleswig-Holstein ; 

 ten were killed, twenty paralysed, fifty-five stupefied' 

 and seven only slightly affected.' In 1905 a 

 tent with 250 people in it was struck, and sixty 

 were left on the ground in various states of insensi- 

 bility; one was killed outright, another breathed for 

 some minutes before dying, the rest recovered. As 

 many as eleven and eighteen persons have been killed 

 by a single stroke of lightning. Vincent mentions a 

 stroke that threw down 1200 and killed 556 out of a 

 flock of 1800 sheep. 



As to the exact way in which lightning causes 

 death, some experiments of Prevost and Battelli, in 

 which the discharges of induction coils and con- 

 densers were employed, seem to show that it is by- 

 central inhibition and cessation of the respiration in 

 many cases, in others bv cardiac fibrillation and stop- 

 page of the heart. The bodies of persons killed bv 

 hghtnmg exhibit no characteristic pathological 

 changes except the production of burns and' the 

 curious subcuticular or subcutaneous stainings known 

 as "lightning figures," that often imitate the frond-- 

 of ferns or leaves or branches of trees, and have given 

 rise to a deal of baseless speculation as to their mode 

 of production. Among the most interesting of the 

 other and far rarer post-mortem lesions observed are 

 lacerations of the soft tissues and fractures of the 

 bones._ The exact mechanism by means of which 

 lightning lacerates tissues and fractures bones is 

 obscure. In cases where the heel is lacerated and 

 the os calcis comminuted, one mav perhaps imagine 

 that an extra development of heat and steam has 

 taken place here, with the result that the electric dis- 

 charge has, so to speak, blown its way out of the 

 body. The example described bv Clark and Rrigham 

 proves that enough heat may be developed in so 

 deeply situated a bone as the orbital plate of the 

 frontal bone to char it, so that it is not unreasonable 

 to supposethat small steam explosions may result if 

 the_ lightning develops a less degree of heat in a 

 moist tissue. But it is not ouite easy to imagine how 

 the tibia and fibula could be broken," without showing 

 any external injury, as in Penfold's case, if the frac- 



