298 



♦ KNOWLEDGE . 



[Oct. 10, 1884. 



" as if with some vague expectation of finding another hat 

 upon it." Dickens himself, when taking part in private 

 theatricals, must often have clapped his hand to his be- 

 wigged head that way.* 



In the talk with Durdles, and again with Deputy, we 

 catch a part of Edwin Drood's jilan for punishing the man 

 who has dealt so murderously with him. Truly he had had 

 " a rather busy afternoon " of it. 



(To he continued.) 



ELECTRIC LIGHT DANGERS. 



By W. Slingo. 



THE very sad accident which occurred last Saturday 

 week at the Health Exhibition, is one which will not 

 be lost sight of for some time to come, and there is no 

 doubt but that the champions of the gas interest will do 

 their best to draw from it a moral which, it is to be feared, 

 will be only too readily received by the great number of 

 people ignorant of the circumstances. It will be remembered 

 that the main features so far known to pertain to the 

 accident were as follows : — Henry Pink, aged 21, an 

 attendant employed in the dynamo shed, had oie haml o i 

 one of the brushes of a 25-arc light Hockhausen machine 

 (generating a ctirrent having an electro-motive force of 

 several hundred volts). By some means he got his other 

 hand either on the other brush or on another part of 

 the machine, with the result that a part of the current 

 passed through his body, and so caused his death ; not 

 instantaneously, however, but after a lapse of some 

 minutes. It transpired at the inquest, which was held on 

 the 1st inst., that strict instructions had been given to each 

 employe not to allow both his hands on the dynamo at the 

 same time. Such injunctions, however, are not always of 

 very great utility, and we may easily suppose tl »', in a 

 moment of absent-mindedness, or when, perhaps, the 

 existence of a small amount of vanity may infuse into 

 the mind of a young man a desire to make an impression 

 upon a wondering and wide-mouthed throng of sightseers, 

 the injunction may be forgotten. It is to my mind a 

 matter of wonder that accidents of this nature have not 

 happened before. We know, too, the old saying that 

 "familiarity breeds contempt," is as true in the treatment 

 of dangerous commodities as between one person and 

 another. One unused to the sight or to the work cannot 

 but be impressed with the apparent recklessness with which 

 many occupations are carried on — such, for example, as the 

 manufacture and storage of explosives. In these occupa- 

 tions, however, the employers do their utmost to prevent 

 accident, arising either from miscarriage in the process 

 employed or negligence on the part of the workmen. But 

 have we any evidence that such precautions have been 

 systematically, or even occasionally, adopted for the protec- 

 tion of the men employed in electric light installations 1 I 

 think we might search the whole country in vain ; and yet 

 what is easier, what more efficacious, than to provide 

 an indiarubber glove for the one hand, leaving the other 

 free to do that work which rarely, if ever, calls for 

 both hands at the same timel Or, again, should 

 there be any difficulty in placing a guard between the 

 brushes of the machine which would permit the hand to 

 be placed on or near one brush, but would not allow it to 

 work round too close to the other t Guards might also be 



* In Wilkie Collins's little story, "Love's Eandom Shot," a 

 kindred use is made of theatrical knowledge. 



very easily devised which would, by imparting, say a slight 

 prick, indicate that one is approaching dangerous ground. 



It is most imperative that every possible precaution 

 should be taken to guard against the recurrence of such 

 an accident as this which has so rudely awakened us to the 

 dangers to which many, perforce, young labourers are 

 daily subjected. 



But the question arises, What are these dangers 1 It is 

 well known that the ordinary incandescent machines may 

 be handled with impunity in their most powerful parts; 

 To the untutored mind this is inexplicable. Nor is the 

 reason so very clearly defined in the minds of more learned 

 men. It is, nevertheless, a notorious fact that a current 

 of as much as 200 volts can do little harm, while a curreni 

 thrice as intense is more than dangerous. There are two, 

 or even three, theories now current to explain the fact. 

 One man supposes that only currents of very high electro- 

 motive force are capable of producing death, and in proof 

 of this, deaths Irom lightning and from currents 

 received from arc - lamp machines are quoted. 

 Another man maintains that it is the strength or 

 volume of the current which wreaks the damage; and, ia 

 proof of this, it may be pointed out that while the electri- 

 city produced by such a machine as the Holtz may have 

 an electro-motive force of several thousand volts, the very 

 high resistance in the circuit prevents it attaining the 

 necessary strength, and so nothing more serious than a 

 twitch or a jerk ensues. There is yet a third theory, which 

 is well put by M. Gariel, in our Parisian contemporary, 

 L'Electricien, in referring to the fatal accident which 

 occurred two years since at the Tuileries. It appears that 

 a well-insulated circuit was established, but that at a 

 particular j)lace one of the wires was enveloped in insulat- 

 ing material, while the other was bare, but supported on 

 porcelain insulators. Two men, named Kenarec and Martin, 

 respectively, came in contact with the bare wire, and they 

 were both killed. According to M. Gariel — " The condition 

 of double contact seems to have been produced in both 

 cases. It appears from the autopsy that both the hands of 

 Kenarec bore distinct traces of burning, and that in the 

 case of Martin the cheek, the neck, and the ear, on the one 

 hand, were distinctly burnt by contact with the wire, 

 whilst on the other, the left hand presented a mark which 

 may likewise be attributed to a burn. 



" We are, therefore, led to the opinion that death re- 

 sulted from a derivation of a part of the current through 

 the body. The intensity of the derived current thus pro- 

 duced could be only a small fraction of the total current, 

 for the resistance offered to the passage of the electricity by 

 the organised parts traversed is enormous in comparison 

 with the resistance of a copper wire six millimetres in 

 diameter, and of a length of a few decimetres, which repre- 

 sents the distance between the points where the derivation 

 was established. But it is far from being proved that, in 

 the action of electricity upon organised beings, it is the- 

 imeasity of the current — that is to say, the quantity of elec- 

 tricity — which determines the results produced. Perhajs 

 even the fall of potential has to be taken into account. 

 Perhaps, also (and we should be personally inclined to 

 admit that it is so), it is the energy which determines the 

 magnitude of the action, i.e., the product of the quantity of 

 electricity by the fall of the potential." 



From the foregoing it is quite evident that we are still 

 a long way from a knowledge of the quality of the elec- 

 tricity which kills a man. Nor are we much nearer a 

 perception of what the effect is upon the system. There 

 is little doubt but that death often results from such a 

 shock to the nervous system as to bring about a stoppage 

 of the heart, but where actual death results, when there is 



