[D8930AAG], Letter from Samuel Insull to Thomas Alva Edison, January 19th, 1889



We have had two more explosions of Junction Boxes. The first one occurred at the corner at the corner of Maiden Lane and Nassau Street in one of the very old form of Junction Box, this box having been underground nearly five years, and possibly a longer period. The last explosion occurred at the corner of 38th. Street and Madison Avenue, in a box laid within the last eighteen months.##Mr. Kruesi is firmly convinced that the cause of the trouble is illuminating gas, which becomes ignited b an arc formed at the time of the blowing off of a safety catch. The peculiar thing is that this trouble [has] not occurred for many years. At the time the Brockton system was laid the same trouble occurred in one of the boxes there, as already related to you by Mr. Kruesi in a former letter.##Within the last two months two boxes have exploded in Chicago, and one in Boston.##The box which exploded in Boston was made by the Tube Company in Brooklyn. The box which exploded in Chicago, and the one which exploded at the corner of 38th. Street and Madison Avenue, were made by us here at Schenectady. The box which exploded at the corner of Maiden Lane and Nassau Street was made by the Tube Company at Kruesi’s Washington Street Mansion. From the fact that the boxes that have caused trouble have been made at such entirely different periods and under entirely different supervision, it would seem that the trouble is radical and not due to any change in the method of manufacture. Are you of the same opinion as Kruesi?##Mr. Kruesi’s theory is that owing to the variation of temperature the air in the box as it gets colder, contracts and forms a partial vaccum which draws the diffused gas trhough the pores of the iron box. Do you think his theory in this respect is correct? If so do you think that this gas is ignited in the manner that Kruesi suggests? If you agree with him on both theories, what remedy would you suggest?##Your suggestions about japanning the box inside and outside, can be followed in the case of new boxes, but what are we to do in the case of the several hundred boxes that are now underground in New York, Chicago, Boston, and other places. The only way that Mr. Kruesi sees out of the trouble, in the case of the present boxes, is to carefully ventilate them every three of six months. Can you offer my suggestion?##If you think it desirable to try any experiments on this subject we can send you a box to Orange.##Will you please send this letter to Mr. Kruesi at Schenectady. I shall be in New York before your reply can reach here. It is a matter which requires immediate attention, as if these explosions continue our reputation will be very seriously affected. Yours very truly Sam Insull##P.S. The last explosion occurred on work that Suebel had charge of. We have told Suebel to explain this matter to you the next time he is at the Laboratory.








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[D8930AAG], Letter from Samuel Insull to Thomas Alva Edison, January 19th, 1889

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