Dunsink Lane, Dublin 15, D15 XR2R

The Dublin Penny Journal

Extract from The Dublin Penny Journal on 15 August 1835 (Vol. IV, No. 163), conducted by P. Dixon Hardy, M.R.I.A.

The learned and munificent Provost of Trinity College, Dublin, Doctor Francis Andrews, having bequeathed to the College £3000, and £250 per annum, towards the building of an Observatory, and furnishing it with proper instruments, which sum was to arise from an accumulation of a part of his property, to commence upon a particular contingency happening in his family, the College, to hasten the execution of the plan, advanced from their own funds a sum considerably exceeding the original bequest; and having elected the Rev. H. Ussher as Professor, sent him to England to order from Mr. Ramsden the best instruments, without limitation of price. Those ordered were, a transit instrument of four feet axis, and six feet focal length, bearing four inches and a quarter aperture, with different magnifying powers; an entire circle of ten feet diameter, moveable on a vertical axis, for measuring altitudes; an equatorial instrument, the circles being five feet diameter; and an achromatic telescope, mounted on a polar axis, and carried by an heliostatic movement, for occasional observations.

The transit instrument arrived as ordered, while Dr. Ussher was Professor; but the great circle for altitudes was not sent from London till many years afterwards, in the time of his successor, the Rev. Dr. Brinkley, now Bishop of Cloyne, who made with it his observations upon the parallax of the fixed stars. This circle was begun, as ordered, with a diameter of ten feet; but was reduced by Ramsden to nine feet, and afterwards to eight feet, of which last size it was finished by Ramsden’s successor, Berge. Only one other astronomical circle, so large as this, has been ever made, namely, that which was finished for Cambridge a few years ago, but which is not capable of moving in azimuth like the Dublin circle. The two remaining instruments, ordered by Dr. Ussher, were never sent from London; but the late Christopher Sharp of Dublin, had almost completed before he died, an equatorial instrument with heliostatic movement, conceived and executed in a style which does great honor to his memory. This instrument carries an achromatic telescope, furnished by Caûchoix of Paris, of which the object-glass is composed of a convex quartz, and a concave flint lens, and exceeds five inches in aperture. The Observatory possesses also an excellent achromatic telescope by Dollond, and clocks by Arnold and Sharp.

The next point to be considered was the arrangement of the building, and the most commodious disposition of the instruments, so as to give to each a situation justly suited to the particular observations to be made. Without loss of time, the Observatory was erected on Dunsink Hill, about four miles north-west of Dublin Castle, and about seventy yards above the level of the sea. It is founded on a solid rock of limestone of some miles extent, which, near the Observatory, rises to within six inches of the surface. The horizon is remarkably extensive, without the smallest interruption on any side, except that on the south the Wicklow mountains, distant about fifteen English miles, rise about a degree and a half.

To give any thing like a correct idea of this building would occupy far more space than we could allocate to the subject. We shall merely notice a few particulars. It is a handsome building, presenting in front a façade of two wings, and a projecting centre, crowned by a dome. Besides apartments for the professor, there are two rooms particularly appropriated to astronomical purposes–the Equatorial and Meridian rooms. The former is immediately beneath the dome, which is intersected by an aperture of two feet six inches in breadth, and is moveable by means of rackwork, so that the aperture may be directed to any point of the horizon. The equatorial instrument rests on a solid pillar of substantial masonry, sixteen feet square. The Meridian room of the west side of the building, is thirty-seven feet two inches long, and twenty-three feet broad in the inside clear, and twenty-one feet high. It contains the transit instrument, and the celebrated eighty-feet Astronomical Circle. The pillars of the transit instrument–which stand on a solid block of Portland stone, nine feet two inches in length, by three feet in breadth, and sixteen inches thick–are seven feet six inches high, their bases three feet from north to south, and two feet six inches from east to west. Each of the supporting pillars consisting of one solid piece, all effects of mortar and cement are avoided, and what is of more importance, all iron cramps are unnecessary. The temperature of the pillars at different heights is shown by thermometers, the tubes of which are bent at right angles, and their bulbs are inserted into the stone, and surrounded with dust of the same stone.

We need scarcely mention, that the Professor who now fills the situation with so much honour to himself and the College, is William Rowan Hamilton, Esq. Royal Astronomer of Ireland.

The Observatory commands on the south side a fine view of the surrounding country, with a gentle declivity to the river, and from thence a varied picture of the rich scenery of the woods of the Phoenix Park, terminated in the back-ground by the majestic grandeur of the Wicklow mountains. To the south-east lies the city of Dublin, distant four miles, the semicircular bay with its shipping, and the great South Wall, extending five miles into the sea, and terminated by the Light-house; the new piers forming Kingstown harbour; the ridge of rocky hills, called The Three Brothers forming the head of Dalkey, and bearing Malpas’s Obelisk on the highest point. On the east and north-east Clontarf and its environs, the Hill of Howth, Ireland’s Eye, and Lambay. From thence to the north-west the prospect is so uncommonly level and extensive as to gratify the astronomer much more than the painter; but even this variety is not without its beauty. To the south-west are the ruins at Castleknock; and to the west, the extended and rich view of Kildare, in which Mr. Conolly’s Obelisk forms a grand and central object.