And I find nothing sensible to do,

Suddenly, however, as we neared our destination he seated himself opposite to me - we had a first-class carriage to ourselves - and laying a hand upon each of my knees he looked into my eyes with the peculiarly mischievous gaze which was characteristic of his more imp-like moods.

'Watson,' said he, 'I have some recollection that you go armed upon these excursions of ours.'

It was as well for him that I did so, for he took little care for his own safety when his mind was once absorbed by a problem, so that more than once my revolver had been a good friend in need. I reminded him of the fact.

'Yes, yes, I am a little absent-minded in such matters. But have you your revolver on you?'

I produced it from my hip-pocket, a short, handy, but very serviceable little weapon. He undid the catch, shook out the cartridges, and examined it with care.

'It's heavy - remarkably heavy,' said he.

'Yes, it is a solid bit of work.'

He mused over it for a minute.

'Do you know, Watson,' said he, 'I believe your revolver is going to have a very intimate connection with the mystery which we are investigating.'

'My dear Holmes, you are joking.'

'No, Watson, I am very serious. There is a test before us. If the test comes off, all will be clear. And the test will depend upon the conduct of this little weapon. One cartridge out. Now we will replace the other five and put on the safety-catch. So! That increases the weight and makes it a better reproduction.'

I had no glimmer of what was in his mind nor did he enlighten me, but sat lost in thought until we pulled up in the little Hampshire station. We secured a ramshackle trap, and in a quarter of an hour were at the house of our confidential friend, the sergeant.

'A clue, Mr Holmes? What is it?'

'It all depends upon the behaviour of Dr Watson's revolver,' said my friend. 'Here it is. Now, officer, can you give me ten yards of string?'

bonus:

'Was there ever a more exact demonstration?' he cried. 'See, Watson, your revolver has solved the problem!’