CATALOGUE. — PRACTICAL ASTRONOMY. 



357 



Observations of the places of the Planets. 



Halley on determining the places of the 

 planets by the fixed stars. Ph. tr. 17'il. 



XXXI. 209. 



Observations of the secondary Planets. 



Lunar Observations. 



Halley on finding the longitude by lunar ob- 

 servations. Ph. tr. 1731. 185. 

 Thinks he can determine the moon's place within a'. 



Mayer on lunar observations. C. Gott. 1753. 



III. 375. 



Maskelyne's lunar observations and compu- 

 tations. Ph. tr. 1762. 558. 



Pigott on the transit of the moon's limb. Ph. 

 tr. 1780. 416. 



Burrow on lunar observations. As. Res. I. 

 433. 

 Recommends that the internal contact of the limbs be 



observed, in order to avoid the effects of irradiation. 



Corrections. Refraction, and Parallax. 



Grischow on the lunar parallax. N. C. Petr. 



IV. 451. 



On the lunar parallax. Ed. ess. II. 91- 



Lalande on the elliptical parallax of azimuth. 

 A. P. 1756. 373. H. 96. 



Maskelyne's concise rules for calculating re- 

 fraction and parallax in lunar observations. 

 Ph. tr. 1764. 261. 



Pingre on parallax, allowing for ellipticity_ 

 A. P. 1764. 362. 



Tables to be used with the nautical almanac. 



Lexell on correcting lunar observations. A. 

 Petr. I. 



Euler on the parallax of a spheroid. A. Petr. 

 III. i. 241. 



Euler on the calculation of lunar observa- 

 tions. A. Petr. 1780. IV. ii. 301. 



Fuss on the corrections of lunar observations. 

 A. Petr. III. J. 310. 



The natural cosine of the true distance is 2 (cos a). {cos 7'). 

 (sec.cj. (seed). (cos. «). (cos/) — cos.g ; a being half the sum 

 of the observed altitudes and the distance, b half the differ- 

 ' ence between the sum of the altitudes and the distance, c and d 

 the observed altitudes, e and /the corrected altitudes, and g' 

 their sum. This is the simple trigonometrical solution. 



Krafft on correcting lunar observations, with 

 a table. A. Petr. VI. ii. 351. I789. VII. 



Not very simple. 



An approximate construction. Kelly^g- 



spherics. 



Draws two lines including an angle equal to the observed 

 distance, sets off the sines of the observed altitudes from the 

 angular point, erects perpendiculars at the points thus found, 

 and the distance of their intersection from the lunar line is 

 the correction, which is subtractive when it lies on the same 

 side with the solar line, and additive when on the opposite 

 side. This correction is measured on the line of chords, 

 calling each degree a minute j it is then reduced by multi- 

 plying it by the horizontal parallax, and dividing by 62 when 

 it is subtractive, but by 53 when additive. This includes 

 the effects of refraction, very nearly. 



Elliot on correcting lunar observations. Ed. 

 tr. I. 191. 



Burrow on the lunar parallax. As. Res. I_ 

 320. 



Garrard's tables for reducing lunar observa- 

 tions. 4. Chelsea, 1800. 

 A short method, for finding the longitude within half a 



degree. 



Mendoza's tables. 4. Lond. 1801. 



Contain a simple method. The author has also lately 

 published some tables for a still more expeditious mode of 

 calculation. 



Leveque. M. Inst. IV. 467. 



Lowe on finding the longitude by land from 



the moon's transit. Ph. M. XV. 97." 

 Andrews's mode of correcting lunar distances. 



Nich. 8. IV. 43. 



A direct solution, deduced from plane trigonometry, em- 

 ploying the squares of the sines. 



Richer and some others have invented mechanical me- 

 thods of correction. 



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