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accuracy accurate adjustment alidade altitude apparatus axis azimuth barometer base base-line bubble centimetres chronometer circle clamp CM CM CM co-ordinates Coast and Geodetic collimation computation contours correction curvature curves desired determined difference direction earth elevation ephemeris equal equation feet formula Geodesy given graduation hachures height hence horizontal hour angle inches instrument intersection interval kilometres latitude length line of sight located longitude mean measured meridian method metres micrometer millimetres necessary object observed obtained oi oi parallax parallel perpendicular plane plane table plumb line pole position probable error reading reference refraction represent right ascension scale screw sextant side sidereal signals slope spheroid stadia star station mark streets surface tangent tape telescope temperature theodolite tion topography transit traverse triangulation United States Coast usually vernier wire zenith distance zenith telescope
Page 398 - All buoys along the coast, or in bays, harbors, sounds, or channels, shall be colored and numbered, so that passing up the coast or sound, or entering the bay, harbor, or channel, red buoys with even numbers shall be passed on the starboard hand, black buoys with uneven numbers on the port hand, and buoys with red and black stripes on either hand. Buoys in channel-ways shall be colored with alternate white and black perpendicular stripes.
Page 22 - If we now add 8 feet to tripod and 8 feet to signal-pole, the visual ray would certainly pass 6 feet above the tangent point, and 20 feet of the pole would be visible from A. II. Elevations required at given distances. — If it is desired to ascertain whether two points in the reconnaissance, estimated to be 44 miles apart, would be visible one from the other, the natural elevations must be at least 278 feet above mean tide, or one 230 feet, and the other 331 feet, etc. This supposes that the intervening...
Page 147 - A sidereal day is the interval between two successive transits of the vernal equinox over the same meridian. It is 3...
Page 68 - ... when the index reads greater than zero and plus when it reads less. Let R be the reading of the index when the balance is suspended by its hook, hook end up. Let W be the total weight of the balance found by weighing it on another balance. Then if...
Page 336 - 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...
Page 280 - D' ^~ to be applied to the approximate altitude for the decrease of gravity on a vertical acting on the density of the mercurial column. It is always additive.
Page 279 - Z = the difference of level between the two barometers ; L = the mean latitude between the two stations ; H= the height of the barometer at the upper station reduced to the temperature of the barometer at the lower station ; or, H= h...
Page 335 - The opposite angles of the quadrilateral adce being supplementary, angle ace and angle ode are subtended by the same chord ae and cae and cde are subtended by the same chord ce ; consequently, the intersection of ae and ce at e must fall on the line db ; or, the segments of two intersecting chords in a circle being reciprocally proportional, the triangles adf and cef are similar, and the triangles cdf and aef...