r his head, and let the line run
off from it. Besides the two men who hold the log and the reel, there is
a third, who has a minute glass in his hand. The minute glass is like an
hour glass, only there is but just sand enough in it to run a minute.
The man who has the minute glass holds it upon its side at first, so as
not to set the sand to running until all is ready.

[Illustration: HEAVING THE LOG.]

At length the man who holds the log throws it over into the water, and
the ship, sailing onward all the time, leaves it there, floating edge
upwards. The man who holds the reel lifts it up high, so that the line
can run off easily as the ship moves on. As soon as the first rag runs
off, which denotes the beginning of the marked point of the line, he
calls out suddenly,--

"Turn!"

This is the command to the man who holds the minute glass to turn it so
as to set the sand to running. He accordingly instantly changes the
position of the glass, and holds it perpendicularly, and immediately
sets himself to watching the running out of the sand. The instant it is
gone, he calls out,--

"Stop!"

The man who is holding the reel, and another who stands by ready to help
him, instantly stop the line, and begin to draw it in. They observe how
many knots have run out, and they know from this how many miles an hour
the ship is going. Each knot goes for a mile.

They do not have to count the knots that have run out. They can always
determine, by the form and color of the last one that passed, what knot
it is. One of the men goes immediately and reports to the captain that
the ship is going so many knots, and the captain makes a record of it.
The other men at once begin to draw in the line, which brings the log in
also at the end of it. This line comes in very hard, for the friction of
so long a cord, dragged so swiftly through the water, is very great. It
generally takes four or five men to pull the line in. These men walk
along the deck, one behind the other, with the line over their
shoulders; and at first they have to tug very hard. The reel man winds
the line upon the reel as fast as they draw it in. It comes in more and
more easily as the part that is in the water grows shorter; and at
length the log itself is soon skipping through the foam in the wake of
the ship, until it comes up out of the water and is taken on board.

They heave the log every two hours,--that is, twelve times for every
twenty-four hours,--and from th