[D8933ACI], Letter from Harold P Brown to Thomas Alva Edison, November 7th, 1889


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[D8933ACI], Letter from Harold P Brown to Thomas Alva Edison, November 7th, 1889

Editor's Notes

The London Daily News published on Tuesday an account of the killing of a horse in this city Monday A.M. Yesterday the Westinghouse people opened fire upon them claiming that the report was all wrong. They cabled for confirmation and I was able to send the inclosed in condensed form over my own signature. Is this worht while to follow up in that benighted land? I also inclose some other matters which may be of interest.####[Enclosure]: Nov. 7 1889####Cable Dispatch sent by request to the London Daily News####Referring to the accident last Monday morning whereby a horse was killed on Fourth Avenue and a police sergeant injured, will say that suh occurrences have become very ccommon since the introduction of the high-tension alternating current. The explanation is simple to anyone haing experience with the peculiarities of that deadly current. In the first place although it was not at the time raining, everything was still saturated with water; a rusted telephone wire had fallen into the street and trailed against an insulated wire carrying the alternating current. The earth connecction thus formed was but a partial one and when the horse shod with iron, struck the wire and pulled it taut, his body being more completely connected to earth, shunted sifficient current through it to produce death.####He fell upon the wire and it is not at all unlikely that the contact of the rusted wire against the street car rail may have allowed sufficient current to sufficient current to pass to heat the point of ontact and finally produce an arc.####The body of the horse when lying on the paving stones, no longer formed so complete aground connection, and when the driver touched it he received a portion of the current, but not sufficient to produce serious injury. The police sergeant then came in contact with the wire between the horse and the pole and deflected sufficient current to knock him down and burn him. The accountsindicate that he too felt upon the wire and its assistant in pulling him off received his quota.####This may seem improbable to English readers; it did to us at first but there havve been so many similar accidents in which the alternating current divided among several living beings from a partially grounded wire, that we know it is only too true. One ase out of a dozen will suffice.####On the A.M of Feb. 5, 1888, before daylight, the driver of a grocery wagon on a prominent street in Buffalo, N.Y, saw his horse fall. He tried to pull his animal up but failed and struck it with his wet whip, receiving sufficient shock to throw him backwards into his wagon. The ground was covered with snow and wet snow was falling. His cries brought to his assistance Isaac Horton, a porter for the Wagner Palace Car Co., who seized the horse by the bridle and was instantly killed####Subsequent examination showed that a telephone wire had broken, one and falling into the street, resisting against an "insulated" wire carrying the Westinghouse alternating current at 1,000 volts pressure. Had it been an arc current in either of these cases the grounding of the wire would have short-circuited some of the lamps and thus indicated to the station attendant that something was wrong; or if an automatic regulator was used, as is generally the case, the coltage would have been immediately reduced and such accidents would have been impossible. With the alternating current, howevver, there is no means of detecting at the station whether the current passes through converters and lamps or leaks to the ground and returns through a human body and a stray wire.####On my complaint the experts of the New York Health Department made an examination on the night of Oct. 14 1889, of the circuits leading from the best equipped alternating current station in this city. One end of a special voltmeter was connected to earth and the other applied in turn to each terminal of nine different circuits. Four of these were in subways and the others on poles. In every case previous tests of insulation resistance showed very high insulation. But with the Health Department tests a difference of potential of from 150 to 600 volts was found to exist upon every circuit, the average being 450 volts.####This is of course an induced current but it is more than sufficcient to produce death in a human being touching a wire while making a ground connection. The armor of the underground cables and the moisture surrounding the insulation of overhead wires termed a conducting [---] for this induced current. This seems incredible and it would of course be impossible in a short laboratory circuit. But when the wires extend for miles the static capacity may be very large. Dr. Hopkinson long ago pointed out the fact that converters were at the same time condensers and might be a source of danger but I think I was the first to show that the conductors themselves might be so regarded. In concluding the report of their tests the Health Dept. recommendedthat the pressure of the alternating current be limited to 260 volts. It is hoped that this limitation will be adopted since the high tension alternating current has already claimed 40 victims, II of whom were killed in the past three months. The London Electrical Review of Oct. 25th has an able editorial on this question--Harold P. Brown####[name mentions: London Electrical Review, Dr. Hopkinson, New York Health Department, Thos Edison, Harold P. Brown, Westinghouse Electric Co., Isaac Horton, Wagner Palace Car Co., London Daily News]




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Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University
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