Go back to the text and re-read a passage where Watson made a discovery. If Sherlock praises him, you've got your answer. I'm sorry if this wasn't much help, but I don't have any text to go off of.
Dirt-disappointed means just extremely disappointed and depressed about something, tired of something.
In Shakespeare's <em>The Tragedy of Julius Caesar</em>, the senate plots against Caesar fearing his growing power and the possibility of him abusing the power he has acquired. After they achieve to murder Caesar by stabbing him multiple times, as we can see in this excerpt, Brutus and everyone involved in the murder are hunted and killed. Moreover, Brutus, who was once like a son to Caesar, feels haunted by the Ghost of Caesar and grows paranoid and desperate. After he was defeated in war by Anthony and Octavian, he knew that he would be captured and executed, for which he decided to commit suicide instead of keep running/fighting.
Therefore, your best answer is "Hold thou my sword hilts, whilst I run on it."
