Later the same year it was attacked by Sarsfield, who fired all day on the stronghold. The marks of the shot are still to be seen upon the castle walls. The besieged, under Captain Curry, held out until reinforcements arrived.
The English army, passing through Birr in 1691, left four hundred wounded men in the castle for two months.
The second Earl of Rosse succeeded to the estates in 1841. His experiments towards improving the reflecting telescope had been begun in 1827 at Birr Castle. He employed local workmen, and the tools, machinery, furnaces, ovens, &c., were all constructed on the spot, many of which are still to be seen.
At length, after many failures, two specula were cast in 1842-43. They each measured 6 feet in diameter, weighed 4 tons, and were of 54 feet focus.
The tube in which one was mounted is 58 feet long and 7 feet in diameter. It is slung on chains between two piers of masonry, and the telescope is moved and supported by a complex system of cast-iron platforms, triangles, and levers.
It is the largest telescope in the world, and cost about £20,000 to construct. Observations were commenced in February, 1845. There are several smaller telescopes at the castle as well.
The present Earl of Rosse is the third Earl, and, like his father, is an eminent scientist.
T. Cooke, “History of Birr,” &c. Cooke, “Picture of Parsonstown.” Brewer, “Beauties of Ireland.” Donovan, “Annals of the Four Masters.” S. Lee, “Dictionary of National Biography.” Parliamentary Gazetteer. Report of Historical MSS. Commission.
Wicklow is situated about twenty-five miles south-south-east of Dublin, and the ruins of the Black Castle occupy an isolated rocky promontory east of the town, and on the south side of the Leitrim river. The name Wicklow is likely to have been of Norwegian origin, but the meaning is uncertain. The Irish name Kilmantan signified S. Mantan’s Church. The castle followed the natural shape of the dark rock on which it was built, and from which, no doubt, the designation “Black” is taken. It was divided from the mainland by a chasm, which was probably bridged in former times. A few fragments of walls, with window openings, are all that remain.
The fortress can never have been of large dimensions if it was confined to the rock on which the ruins now stand.