Results of Astronomical Observations Made During the Years 1834, 5, 6, 7, 8, at the Cape of Good Hope; Being the Completion of a Telescopic Survey of the Whole Surface of the Visible Heavens (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1847 Excerpt: ...the sum of the weights in a set of measures be below 15, the result is considered as entitled only to the lowest unit of value--as decidedly an inferior and unsatisfactory result. If 15, and below 35, the value 2 (expressive of a fair and average degree of reliance) is assigned; if 35 and below 55, it is classed as decidedly good, and valued as 3; above 55 and below 85 (cases occurring usually in favourable conjunctures, and not frequent), the value assigned is 4; while to the very few sets in which the total weight exceeds this limit, and on which particular pains had been bestowed, and a greater than usual number of measurements made, the value allowed is 5. This done, the operation of Let p be the polar distance of a double star; 6 its measured angle of position reckoned as usual from 0 to 360 in the direction nfsp; a the angle of position of an oblique wire across which both the stars are allowed to transit by their diurnal motion; A the interval of their transits across it in seconds of time. Then will the distance of the stars from each other be given by the formula _ 15." A. sin p. cos a sin (a--0) Convenient valves of a are 100 or 110, or (on the other side of the vertical) 260 or 250. Those most commonly used were 100 and 260. The inclination of the oblique wire ought to be towards the opposite side of the meridian to that of the line joining the two stars. In situations not remote from the pole, a high degree of precision is attainable by this method. taking the general mean of several nights' measures is reduced to involve only multiplications by a single figure, and therefore most materially alleviated; while, from the extreme vagueness which necessarily attaches to such numerical estimates of the weight or value of any individual observati...