In the ground plan on the east side, a, a, are the slits or openings in the walls and roof, through which the ce lestial bodies are observed by the transit instrument when in the meridian; b, b, are the stone pillars on which the transit is supported ; c the stone to which the transit clock is attached; d a block of stone, on which an artificial horizon may be placed, when observations are taken, by the method of reflexion, as described by Sir Thomas Brisbane in the Edinburgh Philosophical Transactions, vol. ix. p. 1, and which, when not used, is covered by a board fitted into the floor. In the west ern side, e, e, are openings or slits as before ; f the stone pier, to which the great mural circle is to be fixed ; g, the clock pier ; h, a place for an artificial horizon as be fore: i, is the conical pillar, over which is placed the moveable dome, having an opening, /, in the elevation, as usual, for the purpose of observing ; lc, is the observer's room ; and m, is the entrance in the front.
It is sincerely to be regretted by every frientl to sci ence, as well as to the scientific reputation of Edinburgh, that, from want of funds, proper instruments have not yet been provided, nor a salary for an observer, that might enable him to devote his attention entirely to the pursuits of astronomy.
In the year 1307, a number of gentlemen formed themselves into a society for the promotion of astrono mical science, and have since received a Seal of Cause from the 'AIagistrates and Council of Glasgow, erecting them into a corporate body for that purpose. The funds of this society have been raised by 250 transferable shares of 20 pounds each, wilich are held as heritable property. The observatory stands on Garnet Hill, about a mile north-west from the cross. The situation is unquestionably the best which could have been chosen in the neighbourhood of Glasgow. The designs, which are in the Egyptian style of architecture, were furnished hy Mr. Webster of London. The building is divided in to three compartments; the centre one constitutes the scientific observatory, and is surmounted by a revolving cupola ; the cast division forms thc popular observatory, where the subscribers have the us.e of instruments, and treatises connected with the science; and the west com partment is fitted up for the accommodation of the ob server, and other purposes. In the scientific observa tory time ale three massive stone pedestals ; to one of which a sidereal clock is attached; on another pedestal, twenty feet high, rising without the base of the revolv ing cupola, is placed an excellent azimuth and altitude instrument, which is capable of being fitted up as an equatorial ; on the other pedestal is to be placed a large mural circle, prepared by Troughton. The popular ob servatory is provided with a complete set of instruments for making astronomical observations of the more ordi nary kind. A Herschelian_telcscope, ten feet long, is
used in the terrace, in front of the centre compartment of the observatory, where the projecting wings of the building afford a shelter from thc wind. There arc se veral other telescopes of different kinds, as well as globes, sextants, theodolites, ttc. in this part of the observatory ; a fourteen feet Het schelian telescope is placed on the roof ; an anti-room is occupied by a camera obscura, and a solar microscope ; and other useful instruments are to bc immediately added to this department of the observatory. This valuable institution has been honour ed by the approbation of the most eminent astrononiers in the country, and, we hope, will tend to the more ge neral diffusion of a knowledge of astronomy.
There is also in the Collcge Gardens a small observa tory, provided with the usual instruments, for the use of the professor of practical anatomy, but which do not re quire any separate description.
The observatory of Sir Thomas Brisbane has already been noticed, in our history of ASTRONOMY.
At Aberdeen, in 1694, a lnfty square tower was erect ed upon the top of the west wing of the College, for the purpose of an astronomical observatory, though we are not certain whether it ever was provided with proper in struments.
Soon after the appointment of Dr. Copland to the na tural philosophy chair, he formed the design of erecting an observatory ; and in 1781, succeeded in raising, by subscription, a fund for defraying the expence of the building and necessary apparatus, which was expended in the erection of one on the Castle-Hill. In 1794, this was taken down, in consequence of government wanting the ground for barracks ; and in 1797, a new one was constructed on the west wing of the college, to which the instruments were removed. The principal room is 40 feet by 18, and adjoining to this is a small balcony for making observations out of the meridian.
Belonging to this observatory there are several good in struments ; a transit of four feet by Ramsden ; a quad rant of two feet radius by Troughton; an equatorial by Sisson ; a clock with a gridiron pendulum ; an assistant clock ; a good achromatic telesc.ope of four feet by Dol lond, with a divided object glass micrometer ; a reflect ing telescope of ten feet ; a fine theodolite of sixteen inches by Troughton, constructed on the same princi ples as that used in the trigonometrical survey of Bri tain. There is also here, executed by Troughton, a very fine scale of equal parts, divided by micrometer microscopes, to ten thousandths of an inch, similar to those of Sir George Shuckhurgh, and Professor Pictet of Geneva, the only three ever executed by that artist.