As active as a cat, he had entered by an upper window.
Rovinski spent the night in that building.

He had with him a dark lantern, and he made the most thorough examination of the machinery at the mouth of the shaft.

He was a man of great mechanical ability and an expert in applied electricity.

He understood that machinery, with all its complicated arrangements and appliances, as well as if he had built it himself.

In fact, while examining it, he thought of some very valuable improvements which might have been made in it.