Read it through once

A citizen told me a curious thing about those mines. With all my experience of mining I had never heard of anything of the sort before. The main gold reef runs about north and south—of course—for that is the custom of a rich gold reef. At Ballarat its course is between walls of slate. Now the citizen told me that throughout a stretch of twelve miles along the reef, the reef is crossed at intervals by a straight black streak of a carbonaceous nature—a streak in the slate; a streak no thicker than a pencil—and that wherever it crosses the reef you will certainly find gold at the junction. It is called the Indicator. Thirty feet on each side of the Indicator (and down in the slate, of course) is a still finer streak—a streak as fine as a pencil mark; and indeed, that is its name Pencil Mark. Whenever you find the Pencil Mark you know that thirty feet from it is the Indicator; you measure the distance, excavate, find the Indicator, trace it straight to the reef, and sink your shaft; your fortune is made, for certain. If that is true, it is curious. And it is curious anyway.