. Challenger; the life of a survey ship. Challenger; Hydrographic surveying. THE WEST INDIES 63 rum, that they had added some small contribution of their own to the vast whole of the world's maps. Every day the ship and the boats were slowly covering the sea with lines of soundings. Backwards and forwards they went, first running in towards the shore, then to seaward again; the boats worked along the coast in the shallower water of less than ten fathoms or so, the ship carrying on the sounding to seaward of the boat's limits. The sextant and station pointer method of fixing is used in such cas
. Challenger; the life of a survey ship. Challenger; Hydrographic surveying. THE WEST INDIES 63 rum, that they had added some small contribution of their own to the vast whole of the world's maps. Every day the ship and the boats were slowly covering the sea with lines of soundings. Backwards and forwards they went, first running in towards the shore, then to seaward again; the boats worked along the coast in the shallower water of less than ten fathoms or so, the ship carrying on the sounding to seaward of the boat's limits. The sextant and station pointer method of fixing is used in such cases but as the boats and the ship are moving an officer and a recorder take the two horizontal angles simulta- neously at the word 'Fix', which is heard at frequent and regular Three fixed marks used for fixing. Angle taken second observer Theory of station pointer fixing intervals throughout every long day's sounding. The lines along which it is proposed to sound are drawn on the field-board, and by steering the appropriate course, and by making small altera- tions whenever a fix shows that the ship or boat is being set off the line, an endeavour is made to follow the planned lines which will give a regular sounding coverage of the area. Ocean currents are caused by the friction of wind upon the surface of the sea, and the North-East and South-East Trade Winds set up westerly-moving currents north and south of the equator respectively. These great equatorial currents continue westwards. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ritchie, G. S. (George Stephen), 1914-. New York, Abelard-Schuman
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Keywords: ., bookcentury1900, bookcollectio, booksubjecthydrographicsurveying
