OBSERVATORY, 



the latitude from such observed latitude, 

 they call " working an observation." 



OBSERVATORY, a place destined for 

 observing the heavenly bodies; it is a 

 building usually in form of a tower, erect- 

 ed on an eminence, and covered with a 

 terrace for making astronomical observa- 

 tions. Most nations have had observato- 

 ries, which have been noticed at large in 

 La Lande's Astronomy : of these, the fol- 

 lowing may be mentioned : 



The Greenwich Observatory, or Royal 

 Observatory of England. This was built 

 and endowed in the year 1676, by order 

 of King Charles the Second, at the in- 

 stance of Sir Jonas Moore, and Sir Chris- 

 topher Wren ; the former of these gen- 

 tlemen being Surveyor General of the 

 Ordnance, the office of Astronomer Roy- 

 al was placed under that department, in 

 \vhich it has continued ever since. 



This observatory was at first furnished 

 with several very accurate instruments ; 

 particularly a noble sextant of seven feet 

 radius, with telescopic sights. And the 

 first Astronomer Royal, or the person to 

 whom the province of observing was first 

 committed, was Mr. John Flamsteed ; a 

 man who, as Dr. Halley expresses it, seem- 

 ed born for the employment. During 

 fourteen years he watched the motions 

 of the planets with unwearied diligence, 

 especially those of the moon, as was given 

 him in charge ; that a new theory of that 

 planet being found, shewing all her irre- 

 gularities, the longitude might thence be 

 determined. In the year 1690, having 

 provided himself with a mural arch of 

 near seven feet radius, made by his as- 

 sistant, Mr. Abraham Sharp, and fixed in 

 the plane of the meridian, he began to 

 verify his catalogue of the fixed stars, 

 which had hitherto depended altogether 

 on the distances measured with the sex- 

 tant, after a new and very different man- 

 ner, viz. by taking the meridian altitudes, 

 and the moments of culmination, or in 

 other words, the right ascension and de- 

 clination. And he was so well pleased 

 with this instrument, that he discontinued 

 almost entirely the use of the sextant. 

 Thus, in the space of upwards of forty 

 years, the Astronomer Royal collected an 

 immense number of good observations ; 

 which may be found in his "Historia Coe- 

 lestis Britannica," published in 1725 ; the 

 principal part of which is the Britannic 

 Catalogue of the fixed stars. 



Mr. Flamsteed, on his death in 1719, 

 was succeeded by Dr. Halley, and he by 

 Dr. Bradley in 1742, and this last by Mr. 

 Bliss in 1762 ; but none of the observa- 



tions of these gentlemen have yet, been 

 given to the public. 



On the demise of Mr. Bliss, in 1765, he 

 was succeeded by Dr. Nevil Maskelyne, 

 the present Astronomer Royal, whose va- 

 luable observations have been published, 

 from time to time, under the direction of 

 the Royal Society, in several folio vo- 

 lumes. 



The Greenwich Observatory is found, 

 by very accurate observations, to lie in 

 51 28' 40" north latitude, as settled by 

 Dr. Maskelyne, from many of his own 

 observations, as well as those of Dr, 

 Bradley. 



The Paris Observatory was built by 

 Louis the Fourteenth, in the Fauxbourg 

 St. Jaques ; being begun in 1664, and 

 finished in 1672. It is a singular but 

 magnificent building, of eighty feet in 

 height, with a terrace at top ; and here 

 M. de la Hire, M. Cassini, &c. the King's 

 Astronomers, have made their observa- 

 tions. Its latitude is 48 50' 14" north, 

 and its longitude 9' 20" east of Green- 

 wich Observatory. 



In the Observatory of Paris is a cave, 

 or pit, 170 feet deep, with subterraneous 

 passages, for experiments that are to be 

 made out of the reach of the sun, espe- 

 cially such as relate to congelations, re- 

 frigerations, &c. In this cave there is an 

 old thermometer of M. de la Hire, which 

 stands at all times at the same height ; 

 thereby shewing that the temperature of 

 the place remains always the same. From 

 the top of the platform to the bottom of 

 the cave is a perpendicular well or pit, 

 used formerly for experiments on the 

 fall of bodies ; being also a kind of long 

 telescopical tube, through which the 

 stars are seen at mid-day. 



Tycho Brahe's Observatory was in the 

 little island Ween^ or the Scarlet Island, 

 between the coasts of Schonen and Zea- 

 land, in the Baltic Sea. This observato- 

 ry was not well situated for some kinds of 

 observations, particularly the risings and 

 settings ; as it lay too low, and was land- 

 locked on all the points of the compass 

 except three ; and the land horizon being 

 very rugged and uneven. 



Pekin Observatory. Father Le Comptc 

 describes a very magnificent observatory, 

 erected and furnished by the late Empe- 

 ror of China, in his capital, at the inter- 

 cession of some Jesuit missionaries, chief- 

 ly Father Verbest, whom he appointed 

 his chief observer. The instruments here 

 are exceedingly large ; but the divisions 

 are less accurate ; and, in some respects, 

 the contrivance is less commodious than 



