Elements of Hydrographic Surveying (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 edition. Excerpt: ... for fixing the next station; and so the triangulation may be continued from one point to another along the coast. This same principle may also be employed upon a smaller scale, substituting a boat for the ship. 125. A diagram of triangulation illustrating the arrangement of main and secondary stations in a hydrographic survey is given in Plate I. A study of this will give a clear idea of the objects to be sought in choice of stations; particular attention should be paid to the system of quadrilaterals upon which the main line of the triangulation is extended; the advantages of the quadrilateral over the simple triangle as a basis of computation will be explained later (art. 218). CHAPTER.VI. TOPOGRAPHY. 126. The topographical work of a survey comprises the delineation of all requisite features of the land, including the shore-lines of mainland and islands, all artificial and natural features, and, generally, all things on land a knowledge of whose position may be of value to the navigator, especially as aids in fixing his ship's position. 127. This work divides itself into three general classes: (a) The delineation of prominent features, such as lighthouses, peaks, and other conspicuous landmarks, which are visible from two or more established stations of the survey and can therefore be located by observations of the same nature as those employed for locating secondary triangulation stations; (6) The delineation of the shore-line, which is an essential part of every survey, and which can be properly done only by an observer passing along the shore and locating a series of positions thereon; (c) The delineation of special features, such as lines of equal elevation, courses of streams, and character of ground, which is completely carried...