A Treatise on Topography, for Both Civil and Military PurposesT. Egerton, 1815 |
Parole e frasi comuni
accuracy altitude arc passed axis azimuth barometer barometrical formula bubble calculation centre chord co-efficient coloured glass correction Cotang degrees of Fahrenheit's denoted difference of level division eccentricity equal equation error extremities Fahrenheit's Thermometer formula freezing Point give H and h H sec H₁ heavenly body height horary angle horizon inclination instrument large mirror latitude limb logarithms lower telescope means measured meridian mirrors are parallel number of degrees number of observations observed angle obtained optic axis perpendicular plane plumb line position quantity radius reduction reflecting circle refraction repeating circle repelling screws right ascension second term servations sexagesimal sextant sides signal sin.² sin² small mirror spherical angle spherical excess spherical triangle star stratum subtracted supposed surface taken tance tang temperature terrestrial object tion tricity tube upper telescope yards zenith distances
Brani popolari
Pagina 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...
Pagina 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.
Pagina 167 - ... barometer, observed at each of them. Newton, in his Principia, perfected that theory by showing what regard was to be paid to the diminution of the gravity of the molecules of air, according as the distance from the surface of the earth increased. But, what is very remarkable in so scrupulous an observer of nature, he omitted also to consider the effect of the variations of heat, and of the progressive decrease of the temperature on the density of the beds of air. At this time observations of...
Pagina 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.
Pagina 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.
Pagina 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...
Pagina 72 - ... is directed to the object B on the left,* and the lower one to A on the right ; the upper telescope is then moved according to the order of the divisions until it points to C : the space which it will have passed over on the limb, will be the measure of the an* gle BOC.
Pagina 182 - According to the experiments of Saussure and Watt, the weight of this vapour is to that of air as 10 to 14, when their temperatures and...
Pagina 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.
Pagina 92 - ... of which are equal in length to those of the proposed spherical triangle. It is, therefore, necessary to know the excess of the sum of the three angles of the spherical triangle above two right angles. In order to obtain this, the surface of the triangle must be calculated a priori, by considering it as a plane triangle ; this will give it at least with sufficient accuracy. If we have two sides, b and c with the contained angle A, the surface will be S =; -£ bc sin. A. If we have one side «,...