Long before the introduction of the Log, hour-glasses were used to
tell the distance in sailing. Columbus, Juan de la Cosa, Sebastian
Cabot, and Vasco de Gama, were not acquainted with the Log and its mode
of application; and they estimated the ship’s speed merely by the eye,
while they found the distance they had made by the running-down of the
sand in the _ampotellas_, or hour-glasses. The Log for the measurement
of the distance traversed is stated by writers on navigation not to
have been invented until the end of the sixteenth or the beginning of
the seventeenth century (see _Encyclopædia Britannica_, 7th edition,
1842). The precise date is not known; but it is certain that Pigafetta,
the companion of Magellan, speaks, in 1521, of the Log as a well-known
means of finding the course passed over. Navarete places the use of the
log-line in English ships in 1577.