[LB009259], Letter from Thomas Alva Edison to Francis Robbins Upton, November 6th, 1881

I desire to further call your attention to the fact that the new lamps we are getting are losing their vacuums very badly indeed. The majority of the lamps we are now putting up and on the first or second night or gradually oxidise on the fourth or fifth night. I should say the average life of the lamps now furnished is about twenty five hours This is undoubtedly due to poor work on sealing and may account for the difficulty in getting vacuums. While they are cold the leakage is small but whatever it may be a change has got to be made and more care taken in sealing as we did in earlier days.

Edison, Thomas Alva

Upton, Francis Robbins

Edison Lamp Co

1881-11-06

1880-1889

Letter

Production difficulties and adjustments

Vacuum and glass bulb

LB009259

LB009-F

81:92

Thomas Edison National Historical Park

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