[LB005123], Letter from Charles Batchelor to Edward Hibberd Johnson, September 1st, 1879


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[LB005123], Letter from Charles Batchelor to Edward Hibberd Johnson, September 1st, 1879

Editor's Notes

We have just got your gratifying information that you have `tumbled' to the beauty of the `new design.' Also received yours of Aug 9th and short one day before. We are now making thirty telephones, which we shall send you next week direct to London, and we shall endeavor to give you thirty per week thereafter; the parts are being made by different parties, some by Bergmann and some down East; but the whole thing is put together by us, so as to make sure of your getting them all alike. We shall send you the chalk cylinders all pure, without any phosphate of soda in at all, and you must wet them with a solution of one thimbleful of a saturated solution of phosphate of Soda to four fluid oz of water. When applying to the chalks about four camples hair brushfuls ought to be sufficient for each; This may not appear loud enough at first, but they will come up loud in twwo or three days. The action ofthe Chalk as we understand it is as follows: The water evaporates from the surface, and that from the inside works outwards to replace it; thus always making a more concentrated solution at the surface. In time all the phosphate will be on the surface in the shape of dry crystals when it will no longer work; as a cylinder of pure dry phosphate of Soda will not talk at all. Now this action must be prolonged as much as possible, and therefore it wants `the smallest possible amountof phos. of Soda with the greatest amount of water' & wet the chalk as much ass it will stand, and talk good. As there is no place for the water to go except by evaporation through the small hole where the shaft runs out, I cannot conceive but that it must make a very long time (if properly wetted) before these cylinders play out. You mention that you have to adjust the transmitter occasionally. This should not be, and I presume it is due to your using a carbon battery which gives a spark and [hear?] the carbon when adjusted too far out. Would it not be far preferable to use Leclanche? We always use Callaud and consequently don't have that trouble. We have had a pair of telephones between Edison's house and the office for last 3 weeks and Edison himself acknowledges they are just as loud now, as when put up although we have never touched them at all. Edison thinks it much better for you to get what tools you want there instead of sending them from here and I endorse that, for there are many makers of good amateurs apparatus there, and they can get just what you need. Edison and I have just returned from Saratoga where the meeting of hte A.A.A.S. has been this year. he spoke to 2000 people on Saturady night & exhibited the telephone. This is the first time I believe he has taken the stage and he did it exxcellently. I send you Tribune with account of it. The telephones in Gold & Stock are all in excellent trim except the one in little PHelps shop, which [Mart?] always has to adjust, because `it never worked after he left before,' this of course is what we expected there, but reports of them are very good.




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