The Great Telescope, an amazing feat of engineering and astronomy designed and built by William Parsons, third Earl of Rosse, in the mid nineteenth century, is now fully restored in Birr Castle Demesne and will be the central attraction in Ireland’s Historic Science Centre. Taking as its focal point the genius of one family, the Centre will celebrate Irish achievement in astronomy, engineering, electricity, photography and botany and demonstrate that this heritage is on a par with our well recognised heritage of music, literature and drama.
The central attraction will undoubtedly by the Great Telescope. Built in the 1840s and rebuilt last year, the telescope now moves and looks just as it did 150 years ago and was formally opened by President Robinson at the end of April. Until the early 1900s, Birr (until the late nineteenth century known as Parsonstown) attracted hundreds of people from all over Ireland, Britain, continental Europe and even Imperial Russia, to marvel at the world’s largest telescope. Using the telescope, Lord Rosse discovered the spiral nature of some galaxies, a major breakthrough in astronomical research at the time.
The third Earl of Rosse, educated within the castle walls, was exposed to the remarkable developments in engineering and architecture pioneered by his father, Sir Laurence Parsons, later the second Earl of Rosse. Sir Laurence redesigned and renovated their home as a nineteenth-century Gothic castle; he constructed what was probably the first wrought iron suspension bridge in the British Isles, across the River Camcor in the castle grounds; and he designed and laid out Parsonstown itself. It was natural, therefore, that he would educate his sons in science and engineering rather than in the classics, the more orthodox education for the aristocracy at the time.
William Parsons, third Earl of Rosse, grew up to be an extraordinarily talented engineer and astronomer. His first major astronomical undertaking was to construct what was then the largest reflector telescope in the world—the mirror was three feet in diameter, the tube some thirty feet in length—on the castle’s front lawn. Not content with the amount of light which this telescope could gather, Lord Rosse went on to construct what was referred to as the ‘Leviathan of Parsonstown’. This was a Newtonian reflector telescope with a wooden tube fifty-eight feet in length and a mirror six feet in diameter weighing four tons. The achievement was even more significant when you consider that Lord Rosse had to construct sixty feet high walls to support the telescope; work out the exact combination of tin and copper which would provide the best surface for the mirror; cast the mirrors in a foundry which he built in the dry moat of the castle, employing the local blacksmith and workers from his estate; and fire it with peat from the local bog. The mirror had to be repolished intermittently because it tarnished so rapidly in the moist Irish climate and a special polishing machine was designed, powered by the local river.
When completed, the huge engineering feat proved wonderfully worthwhile: the telescope could gather more light, and hence see further into space than ever before. It was able to show the galaxies in detail and reveal the spiral nature of some of them. It established his scientific reputation and brought astronomers and others from all over Europe to research and study with him at Birr. In 1859, Charles Babbage, the grandfather of the computer, was, appropriately enough, the first person to sign the visitors’ book.
The Great Telescope was dismantled in 1914, the metal work sold for scrap and the mirror, probably the third Earl’s most important achievement, donated to the Science Museum in London. In time, it may be returned to Birr where it was made but in the meantime millions of visitors can view it in London and see what was achieved in Ireland in the last century by remarkable craftsmen.
For most of this century, the telescope has lain quietly disintegrating between its two great walls. Then in the mid 1980s, the seventh Earl of Rosse, great-great-grandson of the third Earl, set about developing a major project to restore the telescope to its original condition. In the last few years, the Office of Public Works and Shannon Development accepted that not only was the telescope a national monument but that if properly exploited, it could become a unique attraction and provide a much needed tourist facility for the Midlands. And so State and European funds were granted and an additional £1 million was raised from private donors in order to restore the telescope and to create Ireland’s Historic Science Centre in a series of scientific galleries.
To find a company which could rebuild this enormous mechanism without any extant drawings proved quite a challenge. The Birr Scientific and Heritage Foundation was lucky to find Michael Tubridy, of Denis O’Leary & Partners, engineer and amateur astronomer who has dedicated the last three years to this project. To find competent engineers and craftsmen to re-make a fifty-eight foot tube, cast and install the metalwork, create the extraordinary Heath Robinson type wheels, pulleys, galleries and gantries was also quite a challenge. However, Owen MacCarthaigh read about the proposed restoration and formed a company, Universal Works, to pitch for the contract. Owen’s dedicated team has created the whole working mechanism as an exact replica of the original.
The telescope is open to the public every day of the year. It now operates at the touch of a button but over the summer on Sundays it is planned to operate the massive structure in its original manual manner so that visitors to the Demesne can get an understanding of the enormity of the achievement in the middle of Ireland in the middle of the last century. A small exhibition on the building of the telescope in 1843 and its rebuilding in 1996 is also open daily from 11am to 6pm.
Brigid Roden is Project Director of Ireland’s Historic Science Centre, Birr Castle Demesne.
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