Narayan Singh coughs either of two ways--once, deep bass, for all's well; twice, almost falsetto, for a hint of danger.

This time it was the single deep bass cough.

But it was followed after half a minute by the two high-pitched barks, and Grim held up a hand for silence.

At the end of perhaps a minute there came from the veranda a perfect imitation of the lascar's ungrammatical, whining singsong from a fo'castle-head: "Hum dekta hai!--I'm on the watch." Grim nodded--to himself, I suppose, for none had spoken to him.
"Do you mind stepping out and getting that letter from him, Ramsden?
Keep in the shadow, please, and give him this pistol; he may need it." So I slipped out through the screen door and spent a minute looking for Narayan Singh.

I'm an old hunter, but it wasn't until Narayan Singh deliberately moved a hand to call attention to himself that I discovered him within ten feet of me.
The risk of being seen from the street in case some spy were lurking out there was obvious.