[LM302001], Letter from Alfred Ord Tate to Chesapeake and Ohio Railway Co, M B Leonard, December 10th, 1889


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[LM302001], Letter from Alfred Ord Tate to Chesapeake and Ohio Railway Co, M B Leonard, December 10th, 1889

Editor's Notes

I have your letter of 2nd inst. And beg to say that you have overlooked the advantages possessed by our cells for telegraph work. It is true that the voltage is not very high, but this is more than compensated for by their low internal resistance, viz., .025. In other words, 100 of our cells in series have a combined internal resistance of only two and a half ohms, while 100 gravity cells in series have over 200 ohms resistance. As you, of course, know a very considerable portion of the current is lost in the battery where gravity cells are used, causing frequent interruptions in wet weather which reduces the resistance of outside lines, and therefore, increases the relative proportion of current consumed in the battery. With our cells practically all the current is delivered on the lines, regardless of conditions of weather. Our zinc never requires cleaning. We can run ten, twenty or thirty wires from a single battery which affords opportunity for the concentration of main line batteries at central points. This means a saving in both investment and maintenance. On local sounder work, we made a test and ran fifteen sounders from two of our cells. You can reckon on a saving here also. In fact, these cells deliver a regular dynamo current and I would like to make you an estimate for the equipment of some of your lines.##Haven't you got a number of wires running out from some centre which could all take current from one battery? If you will give me a diagram of these, indicating the length of each, its total resistance, including relays, the number of cells in use on each and their location, I will furnish you a complete estimate with diagram of proposed arrangement and cost of maintenance--all in detail, which I feel sure will interest you.##We make cells of different sizes, the capacity depending upon the work required. I will kow exactly what is required on your lines when I get the above data.##How much current does the motor take which you mention? We make cells 600, 300 and 150 ampere hours capacity.




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