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Show Charts Are Essential in Modern Sea Vessels Charts are to the seamen what road maps are to the motorist. Glance at a chart and observe the thousands of mysterious little figures fig-ures and letters which cover the portions devoted to various oceans. These are of the utmost importance to the seaman, telling him the depth of water and what lies beneath him, says Pearson's Weekly. By means of compass and sextant the captain of a ship fixes what he calculates to be the exact position of his vessel. On the chart appears, say, the letter "r," denoting that beneath lies rock. To make quite sure that he is not heading the ship to destruction on some undiscovered sandbank, he takes soundings. Standing on either side of the bridge is a steel framework on four legs with a large drum and above this is fixed a dial marked in fathoms. fath-oms. On the drum many thousands of feet of thin steel wire are wound. At the end of the wire is a short length of special non-kinking rope to which is tied a 28-pound weight. The base of the lead weight, known simply as the "lead," is hollowed hol-lowed out in the form of a shallow cup in which is placed a quantity of tallow. Fastened securely to the length of rope is a slim brass container. con-tainer. Into this is placed a narrow glass tube sealed at one end, and graduated along its length in fathoms, fath-oms, with a thin line of red chemical chem-ical running up the center. The whole instrument is then swung out clear of the ship's side on a boom and let go. Immediately bottom is touched, the lead is hove in by an electric motor and swung inboard once more. The tube is examined to show where the action of the water forced up it by pressure has removed re-moved the chemical, the actual depth of the water, while the tallow is scrutinized for any particles of sand or clay. Before the invention of the present sounding machine by Lord Kelvin, methods of sounding in deep water were cumbersome, lengthy, and not always reliable. The lead used was of the same size and shape approximately approx-imately as that used today. Sailors were lined along the side of the ship from bow to stern on platforms called "chains." The leading man held the lead, to which were attached at-tached many thousands r.f feet of rope on which were marks indlcat ing depth in fathoms. |