[LB034065], Letter from Edison Phonoplex System, Alfred Ord Tate to Pennsylvania Railroad, Harry Fondersmith, November 15th, 1889


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[LB034065], Letter from Edison Phonoplex System, Alfred Ord Tate to Pennsylvania Railroad, Harry Fondersmith, November 15th, 1889

Editor's Notes

"I have had a conversation with Mr. Logue in regard to the use of our new battery on your lines. He informs me that you have 29 wires terminating in Philadelphia-14 at 32nd and Market Streets and 15 at Broad St., -and that you desire to know if we can work all these out of one battery. ### In reply I beg to say that we can work the whole of these on 150 cells, so far as I can calculate from the data given me by Mr. Logue. I am going to ask you a few questions, and when I receive your reply I will give you more accurate information. ### I understand that a number of these lines are City wires. Please let me know the exact number; the mileage of the longest one of these; its total resistance, including resistance of relays; the voltage which you wish to secure. ### I separate these city circuits these city circuits, because I understand they are short wires, and it is, therefore, desirable to operate them from an independent battery. ### In regard to the balance of your wires running out of Philadelphia, I want to know (1) the mileage of the longest one of these, (2) its total resistance, including relays, (3) the voltage desired, (4) number of wires. ### If you can conveniently do so, I would like you to let me have a record as follows:- ### CITY CIRCUITS. ### (1) Mileage of each wire ### (2) Total resistance of each wire, including relays. And the same for 'out of town' wires. ### The internal resistance of one of our cells is only 02—local action is less than one-half of one per cent; there is absolutely no cleaning to be done in connection with it; the resistance does not rise but remains constant during its life, and the effect is to render the battery as serviceable in wet weather as in dry. ### Perhaps I can best illustrate its capabilities by means of figures. The data which I use may be incorrect, as Mr. Logue's information was meager, but practically this will make no difference to my present purpose. ### I have assumed that you have nine short city wires, leaving 20 long ones to be grouped in one battery; that you want an initial pressure of 125 volts, and that the total resistance of the longest of these, including relays, is 3600 ohms; therefore, when these 20 wires are 'evened up' with relation to resistance, the total resistance of the outer circuit will be 180 ohms. ### To give you the desired voltage we would install say 150 of our cells; we can neglect the combined internal resistance of these, as it would amount to only 3ohms. These cells have a capacity of 300 ampere hours with one charge of solution; the oxide plates and zincs have a capacity of double the above, so that two charges of solution give 600 ampere hours. ### On my assumed data you would take 7/10 of an ampere out of the battery 24 hours daily, which with one charge would give it a life of three weeks; or six weeks on two charges of solution. In practice this time will be extended I think we can safely say, to one month on one charge, and double that time on two, or even better than that. ### I now wish to call your attention to the merits of this battery in wet weather. The internal resistance of the circuit is 2ohms, and the external 180 ohms. Supposing as an extreme [unclear], this moisture reduces the resistance of your wires ten times, [unclear] your external circuit down to 18 ohms, you would still get 6/7 of the whole current on your lines—only one sevent[unclear] lost in the battery. In short, this battery will work just as well in wet weather as in dry. ### I am making a test now on locals. Think we can upwards of twelve sounders on two cells. I will let you know about this later. ### I shall be glad to hear from you in answer to my queries, and thanking you in anticipation, I am." Yours very truly, A. O. Tate





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