NCERT Solutions Poorvi Chapter 4 The Tunnel, Part II — Let us discuss

… he heard a rhythmic sawing sound coming from the tunnel — the leopard's call.

The text describes it as “a rhythmic sawing sound, as if someone cutting through the branch of a tree”. Suraj asked, “What's that?” and Sunder Singh answered at once, “It's the leopard. I think it's in the tunnel.”

He had also had a warning a few minutes earlier. While trimming his lamp inside the tunnel, “something else — a padded footfall, a rustle of dry leaves — made him stand still for a few seconds, peering into the darkness”.

(i) He was afraid of the leopard.

The proof is in the very next line of the story: “Suraj followed close behind, but he found he was unable to do any shouting. His throat was quite dry.” A dry throat is the body's own sign of fear.

Two things together — the light of the lamp and, above all, the shout of two voices at once.

Sunder Singh advanced into the tunnel raising his lamp and shouting at the top of his voice. Then “Suraj and Sunder Singh both shouted together. Their voices rang through the tunnel. And the leopard, uncertain as to how many terrifying humans were there in the tunnel with him, turned swiftly and disappeared into the darkness.”

He saw the lamp. A week later Suraj was a passenger on the same night mail, sitting at an open window. “He couldn't see Sunder Singh, but he saw the lamp, and he knew that his friend was out there.”

Just before that, the train had rumbled over a small bridge and the engine had let out its shrill whistle — the same signals Suraj had learnt to read while standing at the cutting. So he was already watching for the tunnel when the little light appeared.

His father was going to Delhi on a business trip and decided to take the boy along so that he would begin to learn the family business.

The story gives his father's own grumbling words: “I don't know where he gets to, most of the time. I think it's time he learnt something about my business.”