Why is the exact date of the manuscript important?
The first chapter, Mr. Sherlock Holmes, introduces us to Sherlock Holmes, Doctor Watson, and Dr. James Mortimer. Dr. Mortimer has come to consult Holmes on a matter of great importance: the curse of the Baskervilles.
The date of the manuscript is important because it is a statement/disclosure of the legend that has cursed the Baskerville family for generations; it appears to be the first telling of the black hound legend. The date of the manuscript is 1742; however, the beginning of the black hound legend in the Baskerville family actually goes back to the time of the Great Rebellion/English Civil War (1642-1651). This is when Hugo Baskerville is said to have been killed by a great black beast, shaped like a hound. After the reading of the story, Dr. Mortimer goes on to tell Holmes about Sir Charles Baskerville, who has recently died of a heart attack. His death is only significant to Dr. Mortimer because of the presence of a set of footprints purportedly belonging to a gigantic hound next to Sir Charles Baskerville's body.
Because of the Baskerville curse, Dr. Mortimer feels that the next heir, Sir Henry Baskerville, may be in some danger at Baskerville Hall in Dartmoor. Dr. Mortimer wants Holmes to investigate the truth of the legend set forth in the 1742 manuscript.
I would like to present textual evidence that the 1742 manuscript may have represented the first written statement about the black hound legend by a Baskerville ancestor. That is why the exact date is important. It tells when the Baskerville family first documented the Baskerville curse.
Of the origin of the Hound of the Baskervilles there have been many statements, yet as I come in a direct line from Hugo Baskerville, and as I had the story from my father, who also had it from his, I have set it downwith all belief that it occurred even as is here set forth.