"Give me your hand, Harry, while I look over."

His comrade obeyed, and Jack was able to see about him.

Now on his left, not more than ten feet down, was a large doorway, with a flap similar to the doors on the water-side warehouses, in London, from where the stores are lowered and raised from the barges by means of an iron crane.

"I wonder what place that is?" said Jack; "if I could only reach it, my fall would be very considerably broken."

He had a try.

They fastened their two scarves together, and Harry, making himself a secure hold above, lowered Jack, and the latter swinging backwards and forwards twice, dropped the second time fairly on the ledge.

It was a perilous hold.

But Jack was only second to Nero in monkey tricks, and he held on in a most tenacious manner.

Swinging himself up he pushed his way into a dark and gloomy place.

A low vaulted chamber, dimly lighted by a flickering old lamp.