Wentworth, G. A. (George Albert), 1835-1906 · Boston, Ginn & company · leaf 273
ece of cord having one knot tied in it; the end of the secondknot is marked by a cord with two knots tied in it; the endof the third knot is marked by a cord with three knots tiedin it, etc. A 30-seconds, 28-seconds, or 14-seconds sand-glass (Fig. 3)may be used. The knot is made the same part of… … 3600 s. : 30 s. : : 6080 ft.: x = 50* ft. As a vessel generally overruns herreckoning, the knot corresponding to a30-seconds glass is made 50 ft. The pro-portion would give 47-^j ft. as the lengthFie- 3- of the knot corresponding to a 28-seconds glass, but in practice it is made 46 ft. 8 in.The…
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