“Not at all: we don’t usually sound below fifty feet; and any greater depth than that is called ‘no bottom,’” replied the captain.
“By the deep, eight!” said Bates.
“By the deep, eight,” repeated Dave Windsor. “That means eight feet deep, I suppose.”
“No, it don’t: it means about forty-eight feet. The depth is measured in fathoms of six feet each. The lead-line is marked with two strips of leather at two fathoms, with three strips at three, with a white rag at five fathoms, and with a red rag at seven; at ten fathoms is a leather with a hole in it, and so on. There are no marks at four, six, eight, and nine fathoms. When the leadsman said ‘By the deep, eight,’ the line was under water about six feet below the red rag, or seven fathoms.”
“By the mark, five!” called Bates.
“Just thirty feet,” the captain explained.
“And a half two!”
“Two fathoms and a half. We are shoaling rapidly.”
“Mark under water, two!”
“A little over two fathoms.”