OBSERVATORY, a place destined for observing the heavenly bodies; being generally a building erected on some eminence, covered with a terrace for making astronomical observations.
The more celebrated observatories are, 1. The Greenwich observatory, built in 1676, by order of Charles II. at the solicitation of Sir Jonas Moore and Sir Christopher Wren; and furnished with the most accurate instruments; particularly a noble sextant of seven feet radius, with telescopic sights.
2. The Paris observatory, built by the order of Louis XIV. in the Fauxbourg St Jacques.
It is a very singular, but withal a very magnificent
building, the design of Monsieur Perrault: it is 80 feet high; and at top is a terrace.
The difference in longitude between this and the Greenwich observatory is 2° 20'.
In it is a cave or cellar, of 170 feet descent, for experiments that are to be made far from the sun, &c. particularly such as relate to congelations, refrigerations, indurations, conservations, &c.
3. Tycho Brahe's observatory, which was in the little island Ween, or Scarlet Island, between the coasts of Schonen and Zealand in the Baltic. It was erected and furnished with instruments at his own expence, and called by him Uraniburg. Here he spent twenty years in observing the stars; the result is his catalogue.
4. Pekin observatory. Father Le Compte describes a very magnificent observatory, erected and furnished by the late emperor of China, in his capital, at the intercession of some Jesuit missionaries, principally Father Verbeest, whom he made his chief observer.—The instruments are exceedingly large; but the division less accurate, and the contrivance in some respects less commodious, than that of the Europeans. The chief are, An armillary zodiacal sphere of six feet diameter; an equinoctial sphere of six feet diameter; an azimuthal horizon of six feet diameter; a large quadrant six feet radius; a sextant eight feet radius; and a celestial globe six feet diameter.
Observatories, as they are very useful, and indeed absolutely necessary for astronomers, so they have become far more common than they were. There is a very excellent one now at Oxford, built by the trustees of Dr Radcliffe, at the expence of nearly 30,000 L. At Cambridge there is as yet no public observatory. Over the great gate of Trinity college, indeed, there is one which is called Sir Isaac Newton's, because this great philosopher had used it; but it is gone to decay. It were well if the university would repair and preserve it in memory of that truly great man. In St John's, too, there is a small one. The late ingenious Mr Cotes had used to give lectures in Sir Isaac Newton's on experimental philosophy. There are several very good ones in the Scotch universities; and there is an excellent one lately erected at Dublin.
5. Bramins observatory at Benares. Of this Sir Robert Barker gives the following account, (Phil. Trans. Vol. LXVII. p. 598.) "Benares in the East Indies, one of the principal seminaries of the Bramins or priests of the original Gentoos of Hindoostan, continues still to be the place of resort of that sect of people; and there are many public charities, hospitals, and pagodas, where some thousands of them now reside. Having frequently heard that the ancient Bramins had a knowledge of astronomy, and being confirmed in this by their information of an approaching eclipse both of the sun and moon, I made inquiry, when at that place in the year 1772, among the principal Bramins, to endeavour to get some information relative to the manner in which they were acquainted of an approaching eclipse. The most intelligent that I could meet with, however, gave me but little satisfaction. I was told, that these matters were confined to a few, who were in possession of certain books and records; some containing the mys-
teries of their religion; and others the tables of astro-
nomical observations, written in the Shanferit lan-
guage, which few understood but themselves: that
they would take me to a place which had been con-
structed for the purpose of making such observations
as I was inquiring after, and from whence they sup-
posed the learned Bramins made theirs. I was then
conducted to an ancient building of stone, the lower
part of which, in its present situation, was converted
into a stable for horses, and a receptacle for lumber;
but, by the number of court yards and apartments,
it appeared that it must once have been an edifice for
the use of some public body of people. We entered
this building, and went up a staircase to the top of a
part of it, near to the river Ganges, that led to a
large terrace, where, to my surprise and satisfaction,
I saw a number of instruments yet remaining, in the
greatest preservation, stupendously large, immovable
from the spot, and built of stone, some of them be-
ing upwards of 20 feet in height; and although
they are said to have been erected 200 years ago, the
graduations and divisions on the several arcs appeared
as well cut, and as accurately divided, as if they had
been the performance of a modern artist. The exe-
cution in the construction of these instruments exhib-
ited a mathematical exactness in the fixing, bearing,
fitting of the several parts, in the necessary and suf-
ficient supports to the very large stones that composed
them, and in the joining and fastening each into the
other by means of lead and iron.
"The situation of the two large quadrants of the
instrument marked A in the plate, whose radius is nine
feet two inches, by their being at right angles with a
gnomon at twenty-five degrees elevation, are thrown
into such an oblique situation as to render them the
most difficult, not only to construct of such a magni-
tude, but to secure in their position for so long a pe-
riod, and affords a striking instance of the ability of
the architect in their construction: for, by the shad-
ow of the gnomon thrown on the quadrants, they do
not appear to have altered in the least from their ori-
ginal position; and so true is the line of the gnomon,
that, by applying the eye to a small iron ring of an
inch diameter at one end, the sight is carried through
three others of the same dimension, to the extremity
at the other end, distant 38 feet 8 inches, without ob-
struction: such is the firmness and art with which this
instrument has been executed. This performance is
the more wonderful and extraordinary when compared
with the works of the artificers of Hindostan at this
day, who are not under the immediate direction of an
European mechanic; but arts appear to have declined
equally with science in the east.
"Lieutenant colonel Archibald Campbell, at that
time chief engineer in the East India Company's
service at Bengal, made a perspective drawing of the
whole of the apparatus that could be brought within
his eye at one view; but I lament he could not re-
present some very large quadrants, whose radii were
about twenty feet, they being on the side from whence
he took his drawing. Their description however
is, that they are exact quarters of circles of dif-
ferent radii, the largest of which I judged to be 20
feet, constructed very exactly on the sides of stone-
walls, built perpendicular, and situated, I suppose, in
the meridian of the place: a brass pin is fixed at the
centre or angle of the quadrant, from whence, the
Bramin informed me, they stretched a wire to the
circumference when an observation was to be made;
from which it occurred to me, the observer must have
moved his eye up or down the circumference, by means
of a ladder or some such contrivance, to raise and
lower himself, until he had discovered the altitude of
any of the heavenly bodies in their passage over the
meridian, so expressed on the arcs of these quadrants:
these arcs were very exactly divided into nine large
sections; each of which again into ten, making ninety
lesser divisions or degrees; and those also into twenty,
expressing three minutes each, of about two-tenths
of an inch asunder; so that it is probable they had
some method of dividing even these into more minute
divisions at the time of observation.
"My time would only permit me to take down the
particular dimensions of the most capital instrument,
or the greater equinoctial sun-dial, represented by
figure A, which appears to be an instrument to express
solar time by the shadow of a gnomon upon two quad-
rants, one situated to the east, and the other to the
west of it; and indeed the chief part of their instru-
ments at this place appear to be constructed for the
same purpose, except the quadrants, and a brass in-
strument that will be described hereafter.
"Figure B is another instrument for the purpose
of determining the exact hour of the day by the shad-
ow of a gnomon, which stands perpendicular to, and
in the centre of, a flat circular stone, supported in an
oblique situation by means of four upright stones and
a cross-piece; so that the shadow of the gnomon, which
is a perpendicular iron-rod, is thrown upon the divi-
sion of the circle described on the face of the flat cir-
cular stone.
"Figure C is a brass circle, about two feet diam-
eter, moving vertically upon two pivots between two
stone pillars, having an index or hand turning round
horizontally on the centre of this circle, which is
divided into 360 parts; but there are no counter
divisions on the index to subdivide those on the circle.
This instrument appears to be made for taking the
angle of a star at setting or rising, or for taking
the azimuth or amplitude of the sun at rising or set-
ting.
"The use of the instrument, figure D, I was at a loss
to account for. It consists of two circular walls; the
outer of which is about forty feet diameter, and eight
feet high; the wall within about half that height,
and appears intended for a place to stand on to ob-
serve the divisions on the upper circle of the outer
wall, rather than for any other purpose; and yet both
circles are divided into 360 degrees, each degree be-
ing subdivided into twenty lesser divisions, the same
as the quadrants. There is a door-way to pass into
the inner circle, and a pillar in the centre, of the same
height with the lower circle, having a hole in it, being
the centre of both circles, and seems to be a socket
for an iron-rod to be placed perpendicular into it.
The divisions on these, as well as all the other instru-
ments, will bear a nice examination with a pair of
compasses.
"Figure E is a smaller equinoctial sun-dial, con-
structed upon the same principle as the large one A.
"I cannot quit this subject without observing,
that the Bramins, without the assistance of optical
glasses,
glasses, had nevertheless an advantage unexperienced by the observers of the more northern climates. The serenity and clearness of the atmosphere in the night-time in the East Indies, except at the seasons of changing the monsoons or periodical winds, is difficult to express to those who have not seen it, because we have nothing in comparison to form our ideas upon: it is clear to perfection, a total quietude subsists, scarcely a cloud to be seen, and the light of the heavens, by the numerous appearance of the stars, affords a prospect both of wonder and contemplation.
"This observatory at Benares is said to have been built by the 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 directed that three such places should be erected; one at Delhi, another at Agra, and the third at Benares."
Edinburgh OBSERVATORY. See EDINBURGH.