Surveyor's and Engineer's Companion: a Comcise Treatise on Mathematical Instruments: Containing an Improved Method of Telescopic Measurements...and...the Most Important and Useful Tables and Formulas ...

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Valentine & Company, 1859 - 118 pages

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Page 16 - Mean Time, which is perfectly equable in its increase, is measured by the motion of this Mean Sun; the...
Page 16 - Sidereal Time. — Sidereal time is measured by the daily motion of the stars; or, as it is used by astronomers, by the daily motion of that point in the equator from which the true right ascension of the stars is counted.
Page 28 - As the sum of the two given sides Is to their difference, So is the tangent of half the sum of their opposite angles To the tangent of half the difference of the same angles.
Page 16 - A Solar Day is the interval of time between two successive transits of the sun over the same meridian; and the hour-angle of the sun is called Solar Time.
Page 28 - As the base or sum of the segments Is to the sum of the other two sides, So is the difference of those sides To the difference of the segments of the base.
Page 13 - The whole is mounted on parallel plates and three legs, the same as the theodolite. It is evident, from the nature of this instrument, that three adjustments are necessary. First, to place the intersection of the wires in the telescope, so that it shall coincide with the axis of the cylindrical rings on which the telescope turns ; secondly, to render the level parallel to this axis; and lastly, to set the telescope perpendicular to the vertical axis, that the level may preserve its position while...
Page 16 - Thus, if the apparent time be given, the mean time corresponding to it will be obtained by adding or subtracting the equation of time, according to the precept at the head of the column in which it is found, on page I of the Calendar for each month. If the mean time be given, the apparent time is obtained by applying the equation of time as directed by the precept on page II of the Calendar.
Page 16 - A Sidereal Day is the interval of time between the transit of the vernal equinox over any meridian, and its next succeeding return to the same meridian. It is divided into 24 hours. The sidereal hours are counted from 0 to 24, commencing with the instant of the passage of the true vernal equinox over the upper meridian, and ending with its return to the same meridian.
Page 24 - ... only is just upon the surface, and the water will flow into it. For ordinary purposes of observation, it is only necessary to place the instrument in a retired part of the room, away from the fire, and not exposed to weather, open doors, or passages; but for nice experiments, the observations should always be made in the open air and in the shade, taking especial care that the instrument be not influenced by the radiation of any heated bodies, or any currents of air. When the hygrometer is placed...
Page 28 - Given two Sides and the included Angle, to find the other Angles and the third Side.

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