Traverse Tables

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1872
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Page i - JT) A New and Complete Set of Traverse Tables, showing the Differences of Latitude and the Departures to every Minute of the Quadrant and to Five Places of Decimals. Together with a Table of the lengths of each Degree of Latitude and corresponding Degree of Longitude from the Equator to the Poles; with other Tables useful to the Surveyor and Engineer. Fourth Edition, thoroughly revised and corrected by the Author. Royal 8vo. 12s. London, 1876. Boulger (DC) History of China. By DEMETRIUS CHARLES BOULGEH,...
Page vii - ... the distances, which in fact they usually are in practice. The differences of latitude, and the departures may easily be calculated, the course or bearing and distance being given, or may be found by inspection by certain tables prepared for that purpose. Tables which show by inspection the amount of the difference of latitude, and the departure for any bearing and distance are termed Traverse tables, because, by their means, the resolution of traverses is effected without the necessity of having...
Page vii - ... perpendicular to it, there will in the latter case ,be no difference of latitude, and in the former no departure, and the distance measured will itself express the amount of northing or southing, or of easting or westing due to the change of position. When, however, the course or bearing does not correspond with the meridian or with the perpendicular to it, there will be for every distance measured a certain corresponding change both in latitude and longitude (or departure) ; and as these will...
Page vii - ... lengths, with a view of arriving at any other place situated in any direction with reference to the former, and at any distance therefrom which cannot be reached in the direction of the shortest line connecting them. The angles which the stages or station lines form with the meridian are called in navigation courses, and in geodesic operations bearings, and the lines themselves distances; the quantity of northing or southing made in each distance is called the difference of latitude, and the...
Page xxxix - ... is the remaining part of the equivalent, or 45-4 links. The decimal parts are taken out as whole numbers, removing the decimal point in the equivalent number as many places as it is removed in the original: thus, for -25 yards take out the equivalent for 25 yards = 1 chain 13-6 links, or...
Page xli - ... line ; ie, a portion of a spiral cutting all the meridians over which it passes at the same angle ; but where the lines are so short, as in a survey is generally the case, the difference between the lengths of a straight line, a circular arc, or a rhumb line, drawn between any two stations, is inappreciable, and we may therefore consider our station lines as so many rhumb...
Page xli - ... considered as identical ; for an equal amount of departure, ie, the same number of linear units, will measure different arcs of longitude, according to the distance from the equator at which the departure may be reckoned. Thus, at the equator, a departure=6086 feet measures one minute of longitude, whereas at 89 it measures nearly a degree, and proportionately at all intermediate stages.
Page xxxi - With the true latitude and longitude so found, the position of the village would be fixed by the intersection of co-ordinates from the nearest meridian and parallel of latitude on the map, and the position of any other point or place in the survey would be laid down in a similar manner. The traverse-table may be applied to various other uses, as is fully explained in works containing tables of natural sines and cosines, of which they are but an extension : there is one purpose, however, to which...
Page xxxviii - III., pages 92, 93, and 94. It frequently happens that measurements made in one denomination require to be converted into their equivalents of another denomination : for instance, route surveys are generally measured with instruments registering yards or feet ; and circumstances may occur, and do frequently happen, where instruments cannot be readily procured, which induce the necessity of making all measurements of every kind in one or other of the above denominations, Land surveys are however generally...
Page xli - ... be necessary in the tabular differences of latitude, but that the variation in the length of those degrees of latitude lying near to each other is so small as to be incapable of representation, excepting in maps of very large scale, and extending over great portions of the earth's surface. To obtain the difference of latitude and the departure for any bearing and distance, with perfect accuracy, by the traverse tables, it is essential that the distance should be an oblique rhumb line...

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