...stood upon the flat leads of the house.
The telescope sits on the strips of lead used for roofing the house.

The barren scene, the sense of loneliness, and the mystery and urgency of my task all struck a chill into my heart. The boy was nowhere to be seen. But down beneath me in a cleft of the hills there was a circle of the old stone huts, and in the middle of them there was one which retained sufficient roof to act as a screen against the weather.
At right, a rocky, desolate moor scene like the one Watson might have crossed in search of the mysterious stranger. From Samuel Rowe's A Perambulation of the Ancient and Royal Forest of Dartmoor (1848).

...a pannikin...."
A small pan.

"It is a lovely evening, my dear Watson," said a well-known voice. "I really think that you will be more comfortable outside than in."
Conan Doyle—through Watson himself—has given us all the clues we need to figure out the identity of this mysterious "stranger." We have been told that he is a gentleman, that he is tall and slender, has Spartan habits, and is able to withstand difficult and trying conditions. Cleverly, Conan Doyle mixes clear hints about who he must be with mysterious innuendos. An example from Chapter 9, when Watson sees the stranger standing on a tor in the moonlight:

He stood with his legs a little separated, his arms folded, his head bowed, as if he were brooding over that enormous wilderness of peat and granite which lay before him. He might have been the very spirit of that terrible place.

Now, as the stranger speaks for the first time, we have our final clue--and yet Conan Doyle waits until the next issue to confirm the plot twist that he has just unveiled.