At this reply Preston entrenched, and next day began to bombard the fortress in earnest. The following night a mine was commenced under the direction of a mason who had been employed in the castle. The garrison, hearing the noise, fired on the sappers, but the darkness prevented the shot taking effect, and in the morning they were underground. Preston continued firing, and destroyed much of the wall and one of the flankers. He said he would break down the fortress about the Governor’s ears. Some of the balls found in the masonry weighed 9 lbs. each. Under cover of a parley the defenders of the mill were withdrawn, and the garrison held out for two days after they had been undermined. A conference was held and the besieged were granted honourable terms. Lord Castlehaven conducted them to Athy. They numbered about eight hundred men, women, and children. Preston seems to have retained possession of Birr until 1645, when for five years it was held by the Confederate Catholic forces. It was taken from the Irish in 1650 by General Ireton, the enemy having burnt it before retreating. The Marquis of Clanrickarde tried to retake it in vain. In 1688 Birr was so infested with robbers that Sir Laurence Parsons took some of his neighbours and tenants inside the castle and closed the gates. This act was magnified to the Government by his enemy, Colonel Oxburgh, who obtained an order from the Lord Lieutenant to put a garrison in the castle. Oxburgh demanded admittance, and Sir Laurence refused until he should hear from Lord Tyrconnel. A siege then began, and when they attempted to undermine the fortress terms of capitulation were agreed upon. Both terms of surrender (1643-1688) are preserved in the castle and have been published in the Report of the Historical MSS. Commission. Sir Laurence and some of his tenants were imprisoned in the fortress. He was tried for high treason and several times reprieved. He was liberated after the Boyne, and appointed High Sheriff for the King’s County. In 1690 the castle garrison, being English, was summoned, but after a parley the enemy retired. 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. Sir Laurence Parsons died in 1698. 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.