Dodge, Mary Mapes, 1830-1905 · [New York : Scribner & Co.] · leaf 913
ragis changed to that of an angle, the sides of thisangle being marked by two lines of buoys reach-ing backward from the boats. Where these twolines meet, and under the surface of the water,lies the obstruction. So far, so good; but this is not precise enough.In the approaches to busy harbors, for… … ABOARD THE TOWING-LAUNCH. out its approximate position, the surveyor, bymeans of the lead-line, exactly locates and marksit on the map. The advantage of the wire-drag isthat it does not miss anything lying in its sweep,it makes it possible to explore waters rapidly and NATURE AND SCIENCE FOR YOUNG…
Children's literature
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