Cork observatory houses examples of our golden age of astronomy

 

For many years I passed the Crawford Observatory at University College Cork, giving little thought to the building beyond admiring its compact gothic appearance. Then I learned that the observatory is a uniquely complete relic of 19th century Irish astronomy, housing examples of the best international high technology of the day.

The observatory is now being restored to its original splendour, under the supervision of Dr Paul Callanan, lecturer in physics and astrophysics in the physics department, and course director of the new astrophysics degree at UCC.

The 19th century was the golden age of Irish astronomy, marked by many innovations in telescope design and important astronomical discoveries. The largest telescope in the world at that time was built by William Parsons (third Earl of Rosse) at Birr, Co Offaly in 1842, a status it retained until the large telescope on Mount Wilson in California was constructed in 1917.

Parsons discovered the spiral structure of some galaxies using his giant telescope, a crucial step towards the realisation that huge stellar systems exist outside our own galaxy.

The Crawford Observatory was built in 1878, partly funded by local businessman William Crawford (of Beamish and Crawford brewery fame) and the Duke of Devonshire. It has the distinction of being the only observatory on a university campus in Ireland. The observatory reflects the ecclesiastical style of the early (and still the finest) buildings at UCC.

The Crawford Observatory is a monument to the skills of the Dublin firm of Thomas (18001878) and Howard Grubb (1844-1931). By the end of the 19th century this Rathminesbased firm had gained an international reputation as one of the few companies in the world capable of making large telescopes.

It made telescopes for Armagh Observatory and for Dunsink Observatory (Dublin) and Thomas Grubb helped William Parsons (1800-1867) to construct the huge six-foot diameter mirror for the reflector telescope at Birr. In a reflector telescope an image of the starry heavens is formed by a mirror; in a refractor telescope the image is formed by glass lenses.

The Grubb firm made telescopes for observatories all over the world, for example the 48inch Melbourne reflector telescope (1896), the 27-inch Vienna refractor (1880) and telescopes for Madras, Madrid, Mecca and Mississippi.

Between 1890 and 1914 Howard Grubb completed over 90 first-class telescopes, making the Grubbs one of the finest Irish manufacturers of scientific instruments.

The Grubb firm not only made telescopes, but also optical gunsights, range-finders, and periscopes for submarines. The firm became very important to the British war effort during the first World War and, for security reasons, the Ministry of Munitions provided Howard Grubb with a new factory at St Albans, England. By 1922 the factory in Rathmines was closed.

In 1925 Howard Grubb joined another Irishman, Sir Charles Parsons (1854-1931), to form a new company of Grubb and Parsons with headquarters at Newcastle-upon-Tyne. It manufactured telescopes until 1984. Its last telescope was the 4.2 metre William Herschel Telescope on La Palma in the Canary Isles, probably the most scientifically productive of its kind.

Most Grubb telescopes were bought by existing observatories but at Cork Howard Grubb designed the complete observatory, the telescope dome, the three major telescopes - an equatorial telescope, a transit telescope, and a siderostatic telescope - and ancillary equipment. Today the observatory is unique in Ireland for the remarkable state of preservation of its instruments and the original condition of the building.

The equatorial telescope is the largest of the three. It fills the 15 foot wide dome and tracks the stars in the sky using an intricate and very accurate clockwork mechanism. The telescope was exhibited at the Paris Exhibition in 1878, and its design won the gold medal.

The transit telescope is housed in the single-storey east wing of the observatory. Transit telescopes were designed to map accurate positions of stars, necessary, for example, to test Newton's theory of gravitation, and to assist navigation at sea.

Grubb used an innovation on the telescope, scales engraved on a delicate glass disc 30 inches wide and read by light passed through the glass. This greatly increased the accuracy of measurements and this concept was then used in many astronomical and surveying instruments.

A siderostatic telescope was designed primarily to observe the Sun. The Cork instrument in the west wing of the observatory is the first siderostatic telescope Howard Grubb built. Its design is simple and elegant and an important link in the development of this type of instrument.

The restoration of the telescopes, the cataloguing and preservation of ancillary equipment and the general renovation of the building are advancing well, but much is yet to be done. The vital work of restoring the telescopes is being carried out by Bertie McClure from Belfast.

The restored Crawford Observatory will be an invaluable national resource, of great educational value for students, for historians of Irish science and technology and a window for us all into part of our scientific heritage of which we might justly feel proud. As always, of course, restoration work such as this is expensive and the college would welcome inquiries from potential sponsors.

Expanded details on the history and instrumentation of the Crawford Observatory have been prepared by Dr John Butler of Armagh Observatory and can be consulted on the internet at astro.ucc.ie/obs/

(William Reville is a senior lecturer in biochemistry and director of microscopy at UCC)