A Treatise on the Science & Practical Detail of Trigonometrical Surveying, with Their Applications to Surveying in General, (besides a Minute Description, Illustrated by Figures, of the Repeating Circle ...)T. Egerton, 1820 |
Common terms and phrases
accuracy altitude army axis azimuth barometer barometrical formula calculation centre chord co-efficient column correction corresponding Cross-staff depôts determined difference of level direction elevated employed enemy equal equation error extremities fixed formula give glass ground height horary angle horizontal inclination instrument large mirror Lastly latitude length limb logarithms manner means measured mercury meridian method micrometer military needle number of degrees observed angle obtained optic axis parallel perpendicular plane Plane-table plumb line position quantity radius reconnoitrings rectified reduced reflecting circle refraction render requisite respect right line sexagesimal sextant sides sin.² small mirror spherical excess spherical triangle station stratum subtracted sufficient supposed surface survey taken tang telescope temperature thermometer tion triangles tube vertical visual ray wherefore yards zenith distances
Popular passages
Page 53 - Hence, the sum of the interior angles of the polygon is equal to twice as many right angles, wanting four, as the figure has sides.
Page 199 - From the foregoing statements it may be safely inferred that " the mean height of the barometer at the level of the sea being the same in every part of the globe...
Page 56 - ... the axis of the telescope is parallel to the plane of the instrument. If the o...
Page 92 - ... two right angles, the angles so diminished may be taken for the angles of a plane triangle, the sides of which are equal in length to those of the spherical triangle.
Page 195 - T, the temperature of the barometer. ( t, the temperature of the air. !A', the height of the barometer. T', the temperature of the barometer. t', the temperature of the air. Represent by s the height of the lower station above the level of the sea, by L the latitude of the place, and by h the observed height, h', reduced to the temperature T.
Page 183 - COBtained in it, that is, the part of the barometrical pressure which the vapour sustains. The total weight of the bed may be considered as composed of two parts ; viz. of a certain quantity of vapour, the elastic force of which is F, and of a certain quantity of dry atmospheric air, the elasticity of which is H — F ; let p be the whole weight of the bed, if it were entirely composed of dry air, under a pressure H. The weight of the same...
Page 176 - The same relation will subsist in passing from the second stratum to the third, from the third to the fourth, and so on in successsion, at least on the suppositions that have been admitted ; so that we shall have the following equations.
Page 128 - ... first, that we have the equation of the surface of the spheroid of revolution ; then by referring that surface to co-ordinates taken in the cutting plane, we shall obtain an equation between two indeterminate quantities only, and we shall thus have the equation of the curve made by the intersection. To find the equation of a spheroid generated by the revolution of an ellipse about its shorter axis, it must be considered that the generating curve being plane, its equations will be...
Page 207 - ... mean heights of the barometer and thermometer are known. It will be sufficient to combine these given quantities with those analogous to them at the surface of the sea. Now, according to the observations of M. Shuckburg, which are reckoned very exact, the mean height of the barometer at the level of the ocean, for the latitude of 50°, is .83431 yd.; and the mean temperature, at the same latitude, 55°.04 of Fahrenheit's thermometer.
Page 180 - The co-efficient C, which expresses the ratio of the density to the height of the barometrical column, ought therefore to vary in the same proportion, and consequently it will become C (1 —0.002837. cos. 2 4-), which being substituted in the value of X, gives x_ M 7 ~ C ( 1 — 0.002837.