Birr Castle Science Centre and Telescope

There is a lot to see at Birr Castle, but I came for the telescope. Called the Leviathan of Parsonstown, it was the largest telescope in the world from 1845 until the Hooker Telescope was completed at Mount Wilson Observatory, California in 1917.

The Birr Castle Science Centre has displays that take you through the innovative techniques Parson employed to engineer this marvel. He had to improve on metal working methods to cast and grind the huge metal mirrors, then polish a highly reflective surface. He was able to cast two mirrors, 6 feet wide and 5 inches thick, each weighing about four tons. One could be used while the other was re-polished, because they tarnished so rapidly.

The massive 58’ tube of the telescope is supported by walls 23 feet apart, 40 feet high and 71 feet long. Chains, counterweights and a rack and pinion in a circular arc allow the telescope to be adjusted with cranks and handles to view the heavens. The slideshow at the bottom of the page shows close up views of the telescope.

The Potato Famine struck the year the telescope was finished. The Earl, William Parsons, dedicated his time to food distribution and rebuilding the country’s economy in the face of this disaster.  It was not until 1848 that he had the opportunity to use his Great Telescope. Lord Rosse made his telescope available to scientists and others wishing to view the heavens.

With this telescope, William Parsons the 3rd Earl of Rosse studied our moon and the planets of our solar system. He could see the spiral shape of many nebulae. He could even see individual stars in the spiral nebula Messier 51.

His discovery is celebrated by a spiral of lime trees nearby. These are not the citrus lime trees, but a type of linden tree, Tilia cordata greenspire, called lime. They are planted in the shape of the M51 galaxy, still the most known spiral nebula. This illustrates the perspective we see, living in a spiral galaxy.

William Parson’s son, Laurence Parsons the 4th Earl of Rosse continued his father’s work. J. L. E. Dreyer compiled the New General Catalogue of Nebulae and Clusters of Stars using the Rosse Telescope.

“… such instruments had reached a high degree of perfection, and produced some magnificent results. Two telescopes in particular, at this time, were possessed of remarkable power and of gigantic dimensions… The second was raised in Ireland, in Parsonstown Park, and belongs to Lord Rosse. The length of this tube is forty-eight feet, and the diameter of its object-glass six feet; it magnifies 6,400 times, and required an immense erection of brick work and masonry for the purpose of working it, its weight being twelve and a half tons.

“Still, despite these colossal dimensions, the actual enlargements scarcely exceeded 6,000 times in round numbers; consequently, the moon was brought within no nearer an apparent distance than thirty-nine miles; and objects of less than sixty feet in diameter, unless they were of very considerable length, were still imperceptible.”

From the Earth to the Moon, Jules Verne, 1865

William Parsons’s wife, Mary, Countess of Rosse and son, Laurence Parsons were pioneer photographers. They photographed construction of the giant telescope.  Their darkroom and other early equipment are on display at the Birr Castle Science Centre.

Their youngest son, Charles Parsons was a mathematics and mechanical genius. He invented the steam turbine engine, a breakthrough where compressed steam turns a turbine. This breakthrough allowed electricity to be produced at much lower cost than anything earlier. Parsons’ steam turbine also revolutionized marine propulsion, marine transportation, and naval warfare.

Birr Castle Science Centre

Birr Castle Science Centre has interactive exhibits on photography, engineering, astronomy and botany.  It is in what used to be the Birr Castle Stable Block. It has been restored and now displays and curates an extensive collection of scientific and astronomical instruments.

Displays and models illustrate how the telescope was built. Early astronomical instruments and interactive replicas allow you to understand how they were used.

A prime feature of the collection is the Parson’s family cameras, photographs, and photographic equipment dating to the 1800s, the earliest days of photography.

Displays of Charles Parsons electrical and engineering equipment explore his early experiments and analysis. Charles Parsons invented the steam turbine engine. It revolutionized electric production and marine propulsion.

There are also displays on the science of agriculture and the research, experiments and collecting the family dedicated to systematically gathering rare botanical specimens from all over the world.

Next: Birr Castle Gardens >

Click any photo to start a slide show.

Next: Birr Castle Gardens >