Chronology Details

top 1872
15–17 January Designs a district telegraph that he assigns to the American District Telegraph Co.
27 January Transforms his universal private line printer into an electric typewriter for automatic telegraphy.
January–February Fills laboratory notebooks with variations for his universal stock printer and his universal private line printer.
5 February Becomes a partner in J. T. Murray and Co., which later becomes Edison and Murray.
May Delivers first models of improved universal private line printer to Gold and Stock.
May–June Supplies his universal stock printer to the Exchange Telegraph Co. of London.
3 July Agrees to purchase Unger's share in Edison and Unger, thereby dissolving their partnership.
5 November Makes an agreement with Josiah Reiff to provide Edison with an annual salary while he works on automatic telegraph improvements.
14 December The Automatic Telegraph Co. opens for business using Edison's automatic telegraph improvements.
Fall Conducts tests of his automatic telegraph system on the lines of the Automatic Telegraph Co. and the Southern and Atlantic Telegraph Co. between New York City, Washington, D.C., and Charleston, S.C.
top 1873
c. 10 February Meets with William Orton, president of Western Union, and makes a verbal agreement to develop duplex telegraphy.
18 February Edison's first daughter, Marion Estelle ("Dot"), is born in Newark.
March 31 Agrees to develop a roman letter automatic telegraph for Harrington and Reiff.
9–22 April Prepares ten patent applications on duplex telegraphy.
23 April Leaves for England.
23–27 May Conducts tests of his automatic telegraph system for the British Post Office.
c. 1–15 June Conducts tests of his automatic telegraph on a cable stored at the Greenwich works of the Telegraph Construction and Maintenance Co.
25 June Returns to Newark from England.
2 August Drafts caveat that contains the basis of the quadruplex.
25 August Executes patent application for his roman-letter automatic-telegraph perforator.
2 September Sells British rights for his automatic telegraph to a London company.
6 September A carbon rheostat for use in artificial-cable telegraph experiments is finished in the shop.
Summer–Fall Devises and experiments with circuit designs for duplex, automatic, and cable telegraphy using electromagnets and storage batteries to counter inductive effects.
  Studies chemistry handbooks, prepares automatic-telegraph experiments using different metal styli, and executes four patent applications for chemical solutions for telegraph recording paper.
  Resumes experiments with three-key automatic-telegraph perforators.
1 October Demonstrates quadruplex telegraph for several important telegraph officials.
28 October Executes first caveats for roman-letter automatic-telegraph circuits.
Fall Makes Charles Batchelor his principal laboratory assistant and conducts experiments on electrolytic solutions in batteries.
  Works with telegraph inventor-manufacturer Jesse Bunnell on a railway signal device.
Late December Conducts test of his automatic telegraph system for several important telegraph officials.