Root's Military Topography and Sketching: Prepared for Use in the United States Infantry and Cavalry School |
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Page 123
... makes with the true meridian an angle equal to the azimuth of the North Star at elongation . Now multiply the natural tangent of the azimuth by the distance between the two stakes and lay off this result from b to c , on a perpendicnlar ...
... makes with the true meridian an angle equal to the azimuth of the North Star at elongation . Now multiply the natural tangent of the azimuth by the distance between the two stakes and lay off this result from b to c , on a perpendicnlar ...
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Common terms and phrases
accurate adjustment alidade altitude azimuth bearing bisect bubble chain circle clamp clinometer coincidence COMMON LOGARITHMS compass constructed contour contour interval contour line correct course cross-wires declination arc determined direction distance divided divisions draw drawn edge elevation equal feet FIGURE given graduated ground Gunter's chain height hence horizontal equivalents hour inch represents instrument intercepted intersection latitude length limb line of collimation line of sight located marked mean meridian circle meridian line method mile minutes move needle north end object observation obtained offsets oriented paces paper parallel perpendicular plane table plate plotted plumb-bob plumb-line polar axis position prism protractor refraction revolved road ruler sextant side sketch slope solar solar telescope square stadia stakes station straight line subtract surface survey tangent screw telescope tion topographic transit transit telescope triangle true meridian turn vernier vernier scale wire yards zero
Popular passages
Page 128 - ... point of South America. It is now slowly moving "Westward. At all places situated to the East of this line (including the New-England States...
Page 202 - Then carefully turn the arm half-way over, until it rests upon the adjuster by the opposite faces of the rectangular blocks, and again observe the position of the sun's image. If it remains between the lines as before, the...
Page 390 - ... degrees, that being sufficiently near for all practical purposes. The hour angle in the first column indicates the distance of the sun from the meridian in hours, the refraction given for 0 hours being that which affects the observed declination of the sun when on the meridian, commonly known as meridional refraction ; the refraction for the hours just before and after noon is so nearly that of the meridian, that it may be called and allowed as the same. When the table is used, it must be borne...
Page 200 - The right ascension of a heavenly body is the arc of the equator, intercepted between the first point of Aries and the circle of declination, passing through the place of the...
Page 68 - ... having all its members through first wins. Arch Goal Ball The players are divided into groups, and line up in single file in two or more lines facing a basket ball goal. Each line has a basket ball. At a signal each leader passes the ball backward overhead, the next player catches it and passes it in the same way, and so on to the end of the line. When the last player receives the ball, he runs forward and tries to throw it into the basket, standing on a line marked from five to ten feet from...
Page 139 - By means of the primary triangulation, two or three points are usually located upon each plane-table sheet. Within this primary triangulation, and depending upon it, are then located a large number of points, either by intersection, by traverse, or by both methods, forming a geometric framework upon which the sketching of the map depends. Location by intersection should be carried as far as practicable — that is, all points capable of being located in this manner should be so located in order to...
Page 202 - ... so as to clamp the adjuster at any point on the declination arc. Now level the instrument, place the arm h on the adjuster, with the same side resting against the surface of the declination arc as before it was detached. Turn the instrument on its spindle so as to bring the solar lens to be adjusted in the direction of the sun, and raise or lower the adjuster on the declination arc, until it can be clamped in such a position as to bring the sun's image as near as may be between the equatorial...
Page 227 - A mirror //, called the horizon glass, rigidly attached to the frame of the instrument; and 3. The arc on which the angles are read by means of the vernier at the end of the index arm. The planes of the two mirrors are so fixed as to be parallel, one to the other, when the vernier points to zero degrees. 337. Adjustment of Sextant. — Among the more important adjustments of the sextant...
Page 148 - BŁ, intersecting at d; through d draw a line directed to C. Then set up at C, and assuming the point c on the line dC, at an estimated distance from d, and putting the table in a position parallel to that which is occupied at D, by means of the line cd, draw the lines from c to A and from c to B. These will intersect the lines dA and rfB at points a' and b' ', which form with c and da quadrilateral similar to the true one, but erroneous in size and position. The angles which the lines ab and a'b...
Page 379 - The only authorized material standard of customary weight is the Troy pound of the Mint. It is of brass of unknown density, and therefore not suitable for a standard of mass. It was derived from the British standard Troy pound of 1758 by direct comparison. The British Avoirdupois pound was also derived from the latter, and contains 7000 grains Troy.