"His letters were full of allusions to the major.

He and papa were in command of the troops at the Andaman Islands, so they were thrown a great deal together.

By the way, a curious paper was found in papa's desk which no one could understand.

I don't suppose that it is of the slightest importance, but I thought you might care to see it, so I brought it with me.

It is here." Holmes unfolded the paper carefully and smoothed it out upon his knee.
He then very methodically examined it all over with his double lens.
"It is paper of native Indian manufacture," he remarked.