[LM112159], Letter from Arthur Edwin Kennelly to Edison Lamp Co, Francis Robbins Upton, November 2nd, 1889
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Title
[LM112159], Letter from Arthur Edwin Kennelly to Edison Lamp Co, Francis Robbins Upton, November 2nd, 1889
Editor's Notes
The Siemens Alternating Dynamo sent to you yesterday gives 200 mean alternating voltage when running at 1500 revolutions per minute with about 5 amperes in the field circuit. We hope you will return it to the laboratory when your purposes with it are accomplished. ## Mr. Edison's municipal automatic cut out consists of a pair of metal spring strips each connected with one leading wire of the lamp, and separated by the insertion of a lamina of silver sulphide about 0.01" thick. The sample strips tried were about 1/2 x 1/4". The resistance of this cut out is very high normally but falls very rapidly on the application of heat. The sulphide was prepared by the action of [some silver compound] and the precipitate mixed in a crucible under hydrogen then rolled into strips. We tried two or three lamps protected in this way for several days and they showed no appreciable leakage, but a pressure of 100 volts brought to bear upon the strip produced a current through it whose heat instantly reduced the sulphide to metallic silver, so rapidly in fact that the decomposition of the wire leading to the protected lamp only produced a momentary flicker in [illeg] in circuit. The only danger to be feared is apparently the heat in the neck of the lamp where the cutout would presumably be inserted. We did not try [any?] strips in the neck but Mr. Edison did not think the damage too great. ## I have no doubt that the laboratory can furnish the rolled silver sulphide from its chemical department if [application] be made. We have none on hand.
Author
Recipient
Mentioned
Date
1889-11-02
Type
Folder/Volume ID
LM112-F
Microfilm ID
109:368
Document ID
LM112159
Publisher
Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University