THE EARLY YEARS
Watson writes in ‘The Adventure of the Veiled Lodger’ that “Mr. Sherlock Holmes was in active practice for twenty-three years, and that during seventeen of these I was allowed to co-operate with him and to keep notes of his doings.” Watson was wounded in the battle of Maiwand, which took place on 27 July 1880, and the first meeting of Holmes and Watson happened some months later near the beginning of 1881 leading most people to believe that Sherlock Holmes’ career began at this time yet they are neglecting to include the first two recorded chronological cases ‘The “Gloria Scott” ‘ and ‘The Musgrave Ritual’ among other unnamed early cases. At least some of these early cases must have occurred during Holmes’ active practice. ‘The “Gloria Scott”‘ took place during a long vacation presumably between the two years Holmes was at college. In ‘The Musgrave Ritual,’ Holmes says, “For four years I had seen nothing of [Reginal Musgrave], until one morning he walked into my room in Montague Street.” Since Reginald Musgrave was something of a classmate of Holmes at university, we may safely deduce that ‘The Musgrave Ritual’ takes place some five years after ‘The “Gloria Scott”.’

THE GREAT HIATUS
The often named Great Hiatus has been documented in detail in ‘The Final Problem’ and ‘The Adventure of the Empty House’ from Monday, 4 May 1891 until sometime soon after 30 April 1894, which makes three years where Watson and Holmes were separated though I do not believe we can say that Holmes was in ‘active practice.’

RETIREMENT
In ‘The Adventure of the Second Stain,’ Watson writes the following, “So long as he was in actual professional practice the records of his successes were of some practical value to him; but since he has definitely retired from London and betaken himself to study and bee-farming on the Sussex Downs.” Then in ‘The Adventure of the Creeping Man,’ we find this fact: “Now we have at last obtained permission to ventilate the facts which formed one of the very last cases handled by Holmes before his retirement from practice.” The common consensus is that ‘The Adventure of the Creeping Man’ took place in September 1903, and ‘The Adventure of the Second Stain’ was first published in December 1904; therefore, it is safe to presume that Holmes’ retirement took place sometime between these two events. ‘The Adventure of the Empty House’ was first published in October 1903, and I would like to think that Holmes was already retired by this time for, with the exception of the first two novels, Watson appears to be in the habit of publishing stories only when Holmes is not in active practice.

CONCLUSION
The length of time between May 1894 and September-October 1903 is approximately nine and one half years. This leaves thirteen and one half years from late 1877 until 4 May 1891 to complete the 23 years of Holmes’ active practice. The real question remains: Exactly when are the six years that Watson was NOT “allowed to co-operate with” Holmes and “keep notes of his doings”?