[PT032ABU1], Letter from Thomas Alva Edison to Henry W Seely, March 24th, 1889


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[PT032ABU1], Letter from Thomas Alva Edison to Henry W Seely, March 24th, 1889

Editor's Notes

The object of this invention is to produce simple & effective recording and reproducing points for phonographs which while giving a true record & reproduction thereof will permit of being made cheaply and are of such a character as to be readily replaced by inexpert persons another object is the production of a record of such a character that the reproducing point will follow such record truly notwithstanding want of accurate workmanship in the phonograph or imperfections in the Record cylinder##The invention consists 1st in causing the sound waves to be recorded in circular indentations 2nd The reproducing point made circular as a ball 3rd A circular Recording point for recording the circular waves; 4th Both points Removably connected.5 The holder for same-- 6th The weight Fig. 4. lever, slot, limiting stop me & Receiver generally##Firg 1 is Recorder to the usual lever I secure a holder for the record point a-- This is a tube soldered to the lever The Record tool a slides into the tube & is secured by a cement preferbly melted shellac. The tool is round and has a shank which shdes into the tube this insures its being always put in to the same position. The recorrding end of a being perfectly cylindrical on the outside is cupped so as to give an exceedingly keen circular cutting edge all around with a phonograph having 100 threads to the inch the diameter of the cutting edge which I prefer is 40 thousands of an inch hence if one portion of the diameter gets dull the shellac may be softened by heat and a new part of the perfiphery used & this may be done several times before the point is required to be removed as useless until reground hence the recrods will unlike previousl phonographs be recorded circularly as in fig. 8 fig 5 shews Reproducing ball point also fig. 7. The diameter of the ball is 35 thousands of an inch. The advantage of the circular record is that it permits the use of the ball reproducer & this even when the lever carrying it is out of line relative to the record keeps in the record in such a matter as to reproduce perfectly##Of course the two points might be semicircular or slightly oval without departing from the spirit of the invention--##Seeley--notice the Receiver is on same line as those patented lately but this is final form the weight being on point make claims in view of last patent taken out.##Claim Broadly the circular record (you will notice that the hwole ofhte material cut forms a wave [drawings] wave is from a to be old way & abc new way this gives no side walls to cut & for the reproducer point to scratch against. The new way gives a greater surface for wear-- The ball is always parallel to record while old way if point is not paralell don't reproduce exactly & wears out record##Get claim on circular or semicircular Recorder--removably connected Turnable to be used several times etc.##Want this patent well drawn up with extra goo claims as it is what makes the phono a silk finish to the sounds TAE arch 24 1889





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