[LM240637], Letter from Thomas Alva Edison to James Bryant Tonking, New Jersey Zinc Co, April 6th, 1900
https://edisondigital.rutgers.edu/document/LM240637
Transcription
April 6th, 1900 Mr. Joseph B. Tonking New Jersey Zinc Co., Franklin Furnace, N.J. Dear Sir:-- I do not think the Roebling people are in a position to advise you about the rope. They have never had the same conditions to contend with and when we went to them they could not advise us; I then tried a great number of experiments. One experiment was the running No. 4 Elevator with crucible steel. 19 wire strand by a motor for seven weeks, 10 hours per day. This elevator continuously carried 700 tons per hour during the whole of the experiment the ore delivered at the top, dropped down a chute back into the bottom of elevator [illegible] up the elevator again. There were many breaks in the siren. I then rigged up 5 wheels with very small diameter and tried every rope being made, except Tiller rope, and found that under the severe tests, our special rope we use in elevators stood longer than any other. Regarding the reduction of speed to 80. I think my point is well taken; the weight of 50 buckets and bottom wheels being one side of elevator, is 18500 lbs., wheras if you are running 100 tons per hour, the total ore in the 80 buckets will only be 1245 lbs running