[D8238ZER], Letter from Charles Batchelor to Thomas Alva Edison, December 1st, 1882


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[D8238ZER], Letter from Charles Batchelor to Thomas Alva Edison, December 1st, 1882

Editor's Notes

No. 381. Some US lamps are short-circuited in plaster socket (have remedied defect in ours). Couldn't believe it (sketches of faults]. Also please put better varnishing on lamps coming here; moist atmosphere gets into the plaster; essential to varnish the bottom. "Since finding the cross I have carefully investigated the lamps which suddenly explode (a phenomenon I have never explained satisfactorily to myself)" and think it's often due to wires being close together and a little extra current expands wires in the shank so that they buckle and make contact with each other. "Dampness in the plaster will account for high volt lamps in some cases. My volts used to range up to 112 but now I keep all my lamps at about 90 Fahr for 2 days before varnishing and testing and now I very seldom get one above 106 or 107. More than a page of TAE marg: "Explosion is due I think to arcing. We have fixed the wires in inside part by using insulated wire. Will tell Upton about varnishing. There must have been some change in your carbonization to bring volts down as Upton can't see how a drop of 2 volts could take place in the wet plaster," etc. Have got new compound for sockets to replace plaster: "I am trying to stick mica together which does splendidly." Gives info on expts common oxide magnesia and solution chloride of magnesia, suggests Batch do own expts with proportions.




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