## An Introduction to Spherical and Practical Astronomy |

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adjustment arithmetical mean Astronomy axis body celestial sphere change of declination Chapter circumpolar star clock correction clock error co-ordinates collimation computed constant cos2 culmination denote determined difference of azimuth difference of longitude e2 sin2 east ecliptic equal altitudes equations of condition equatorial intervals Example expressed formulae gives Greenwich mean hence horizon images index correction large number latitude mean error mean solar mean wire measured meridian passage middle wire moon's multiplied Nautical Almanac number of errors number of observations parallax parallel perpendicular plane pole position prime vertical probable error probable values radius readings reduced right ascension screw seconds sextant sidereal clock sidereal day sidereal interval signal solar day spherical star's substituted sun's hour angle tangent telescope tion transit instrument transit observations triangle unknown quantities vernal equinox vertical wires whence zenith distance

### Popular passages

Page 108 - The sum of the angles of a spherical triangle is greater than two and less than six right angles ; that is, greater than 180° and less than 540°. (gr). If A'B'C' is the polar triangle of ABC...

Page 73 - O between the equator and the pole and between the zenith and the horizon are both right angles, the altitude of the pole above the horizon is equal to the latitude of the place.

Page 6 - ... sin a sin B = sin b sin A sin b sin C = sin c sin BI (3) sin c sin A = sin a sin...

Page 141 - A weighted arithmetic mean is obtained by multiplying each value by some non-negative weight before summation and then dividing the sum of the products by the sum of the weights.

Page 5 - The longitude of a place is, therefore, measured by the arc of the equator intercepted between the meridian of the place and that of Greenwich ; or, which is the same thing, by the spherical angle at the pole included between these meridians.

Page i - Uranography. 30 cents. Lessons in Astronomy. Including Uranography. By Professor CHARLES A. YOUNG. Prepared for schools that desire a brief course free from mathematics. $1.20. An Introduction to Spherical and Practical Astronomy. By DASCOM GREENE, Professor of Mathematics and Astronomy in the Rensselaer Polytechnic Institute, Troy, NY $1.50.

Page 3 - ... the body. This last circle is nothing else than the meridian of the body. The horary angle is measured by the arc of the equator which has passed, or will pass, under the meridian of the observer, between the instant of observation, and the moment when the heavenly body is upon this same meridian. Azimuth. The azimuth of a body, is the arc of the horizon intercepted between the south point, and that in which a vertical circle passing through the zenith and the body, cuts the horizon. Amplitude....

Page 114 - The name is first mentioned in the Report of the Superintendent of the United States Coast Survey for 1856.

Page 46 - ... fasten, to the up-and-down piece, the collar into which the telescope screws. This adjustment is not very liable to be deranged. Having now gone through the principle and construction of the sextant, it remains to give some instructions as to the manner of using it. It is evident that the plane of the instrument must be held in> the plane of the two objects, the angular distance of which is required: in a vertical plane, therefore, when altitudes are measured; in a horizontal or oblique plane,...