OBSERVATORY. 



in those of the Europeans. The chief 

 are, an armillary zodiacal sphere of six 

 Paris feet diameter, an azimuthal horizon 

 six feet diameter, a large quadrant six 

 feet radius, a sextant eight feet radius, 

 and a celestial globe six diameter. 



Bramin's Observatory at Benares, in the 

 East Indies, which is still one of the prin- 

 cipal seminaries of the Bramins, or priests 

 of the original Gentoos of Hindostan. 

 This observatory at Benares, it is said, 

 was built about 200 years since, by order 

 of the Emperor Ackbar ; for as this wise 

 prince endeavoured to improve the arts, 

 so he wished also to recover the sciences 

 of Hindostan, and therefore ordered that 

 three such places should be erected ; one 

 at Delhi, another at Agra, and the third 

 at Benares. 



Wanting the use of optical glasses, to 

 magnify very distant, or very small ob- 

 jects, these people directed their atten- 

 tion to the increasing the size of their in- 

 struments, for obtaining the greater ac- 

 curacy and number of the divisions and 

 subdivisions in their instruments. Ac- 

 cordingly, the observatory contains seve- 

 ral huge instruments of stone, very nice- 

 ly erected and divided, consisting of cir- 

 cles, columns, gnomons, dials, quadrants, 

 &c. some of them of 20 feet radius, the 

 circle divided first into 360 equal parts, 

 and sometimes each of these into 20 other 

 equal parts, each answering to 3', and of 

 about two tenths of an inch in extent. 

 And although these wonderful instru- 

 ments have been built upwards of 200 

 years, the graduations and divisions on 

 the several arcs appear as well cut, and 

 as accurately divided, as if they had been 

 the performance of a modern artist. The 

 execution, in the construction of these 

 instruments, exhibits an extraordinary 

 mathematical exactness in the fixing, 

 Bearing, fitting of the several parts, in 

 the necessary and sufficient supports to 

 the very large stones that compose them, 

 and in the joiningund fastening them into 

 each other by means of lead and iron. 



We have referred to this article from 

 the EQJJATORTAI, for some account of 

 practical astronomy, and the instruments 

 used in this branch of science. 



By practical astronomy is implied the 

 knowledge of observing the celestial bo- 

 dies, with respect to their position and 

 time of the year, and of deducing from 

 those observations certain conclusions, 

 useful in calculating the time when any 

 proposed position of these bodies shall 

 happen. For this purpose, it is neces- 

 sary to have a room or place 



ly situated, suitably contrived, and fur- 

 nished with proper astronomical instru- 

 ments. It should have an uninterrupted 

 view from the zenith down to, or even 

 below, the horizon, at least towards the 

 cardinal points ; and for this purpose, that 

 part of the roof which lies in the direc- 

 tion of the meridian, in particular, should 

 have moveable covers, which may easily 

 be moved, by which means an instrument 

 may be directed to any point of the hea- 

 vens between the horizon and the ze- 

 nith, as well to the northward as south- 

 ward. This place, called an observatory, 

 should contain the following instru- 

 ments : 



I. Jl Pendulum Clock, for showing 

 equal time. This should show time in 

 hours, minutes, and seconds ; the observ- 

 er, by hearing the beats of the pendu- 

 lum, may count them by his ear, while, 

 his eye is employed on the motion of the 

 celestial object he is observing. Just be- 

 fore the object arrives at the position de- 

 scribed, the observer should look on the 

 clock and remark the time, suppose it 

 9 hours, 15 minutes, 25 seconds ; then 

 saying, 25, 26, 27, 28, &c. responsive to 

 the beat of the pendulum, till he sees 

 through the instrument the object arriv- 

 ed at the position expected ; which sup- 

 pose to happen when he says thirty-eight, 

 he then writes down 9h 15' 38" for the 

 time of observation, annexing the parti- 

 cular day. If two persons are concerned 

 in making the observation, one may read 

 the time audibly while the other observes 

 through the instrument, the observer re- 

 peating the last second read when the de- 

 sired position happens. 



II. An Achromatic Refracting Telescope, 

 or a reflecting one of two feet at least in 

 length, for observing particular pheno- 

 mena. See TEIESCOPE. 



III. A Micrometer for measuring small 

 angular distances. See MICROMETER. 



IV. A Quadrant, for a description of 

 which, and its several uses, we refer to 

 the article QUADRANT. We may, how- 

 ever, observe, that besides Hadley's 

 quadrant, which is described there, we 

 have the mural quadrant, which is reck- 

 oned one of the most useful and valuable 

 of all the astronomical instruments, and 

 is generally fixed to the side of a stone 

 or brick wall, and the plane of it is erect- 

 ed exactly in the plane of the meridian. 

 There is also a portable astronomical 

 quadrant, which is in high estimation, on 

 account of its being capable of being 

 arried to any part of the world, and put 



