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Note added in 1995.
The standard history of Armagh Observatory is "Church, State and
Astronomy in Ireland - 200 Years of Armagh Observatory" by
J.A. Bennett , published by The Institute for Irish Studies,
Queens University, Belfast and Armagh Observatory in
1990. Available from Armagh Observatory in paperback, price 10.00
pounds sterling + post and packing.
Text taken from an illustrated catalogue prepared for the exhibition to commemorate the bicentenary of Armagh Observatory in 1990/91, Seeing Stars , C.J. Butler, Armagh Observatory 1990. Copies available from Armagh Observatory, price one pound plus post and packing.
Ownership of the originals for the illustrations is indicated by italics in the captions and copyright remains with the owners.
See also:
Other Historical Accounts and Resources
Following the last great ice-age, which ended about 10,000 BC, the landscape of Ireland evolved from a bleak tundra to, first birch, then oak forest. As the ice receded it revealed the undulating countryside which covers much of the counties of Armagh, Monaghan and Cavan today. Also, where rocky outcrops had withstood the grinding ice, prominent hills, such as the one which lies in the centre of the City of Armagh , became exposed. It was to this hill that the earliest known settlers of Armagh came - the neolithic people. Remains of their occupation are still to be seen in various stone monuments which were erected in the neighbouring countryside. One such site was recently revealed by excavations in Scotch Street, Armagh.
Whilst we have no written records from this period, (5,000 - 2,300 BC), the interest of the neolithic peoples in the movement of astronomical bodies is demonstrated in the layout of some of their major constructions, such as the great burial tumulus at Newgrange. Here the alignment of the passageway leading to the central chamber with the midwinter sunrise displays to posterity the architectural skill and the interest in astronomy of these early settlers of Ireland.
In succeeding centuries, the centre of occupation moved from the hill of Armagh to a site about 2 miles west, where, on the hill of Navan, one of the celtic Queens called Macha built a magnificent palace. Here, at the Capital of Ulster, the exploits of the legendary Cuchullain and the Kings of Ulster were preserved in the oral tradition.
After the destruction of Navan, the centre of influence moved back to the present site of Armagh, probably in the 5th century AD. In this century, also, following his conversion of the King to Christianity, St Patrick founded his first church in Armagh. For the next four centuries Armagh was renowned throughout Europe as an ecclesiastical centre and was regarded as the Metropolis of Ireland. During this period the religious colleges in Armagh were said to have had several thousand students.
Amongst the various duties of the teachers at the monastic university was the recording of important historical events. Many of these relate to the activities of the ruling families, outbreaks of wars and civil disturbances etc, but occasionally they also noted various astronomical apparitions, such as comets or eclipses. These are the earliest recorded astronomical observations from Armagh and are compiled in the medieval manuscript The Annals of Ulster.
In later centuries, following the Viking and Norman invasions, the centre of power in Ireland moved to coastal towns such as Dublin and Drogheda and by 1600 Armagh was only a collection of ruins and thatched cabins ( contemporary map .) During this period, Armagh and its surroundings, became a battlefield for the continuing strife between the opposing forces of the Earl of Tyrone and Elizabeth.
The Archbishops of Armagh at this time only visited their primatial capital occasionally and preferred to reside in Drogheda. One such Archbishop, the great scholar James Ussher, is renowned for his calculation of the age of the world.
The 18th century, often referred to as the age of enlightenment saw a steady increase in the study of the sciences. The abstract theorising of the Greek philosophers and the hit-and-miss approach of the medieval alchemists gave way to the sound scientific methods of experimental science as founded by Galileo and Newton in the previous two centuries. Basically this involved the testing of theories by experiment or observation; thereby establishing whether or not the theory was correct. Astronomy in the 18th century, although it followed the rising tide of experimental and observational science, was also seen as important for the practical science of Navigation. Towards the end of the century several events and influences brought astronomy to prominence in the public eye.
These were:
During the 17th and 18th centuries, trade with the Empire, particularly with the new world and India, was becoming increasingly important to Great Britain. With only primitive navigational methods at their disposal many ships were lost on the high seas and it soon became evident to the maritime authorities that improvements in the techniques of navigation were required. This lead directly to the setting up of the Royal Greenwich Observatory in 1675 which was charged with the duty of improving the accuracy of the positions of stars which could be used by mariners for determining their position at sea.
In the 17th century the great mathematician, Sir Isaac Newton, had proclaimed The Universal Law of Gravitation, which postulated that the same force that pulled the falling apple to the ground also held the moon in its orbit around the Earth and the planets in their orbits around the Sun. To accurately test Newton's theory, precise measurements of the planets were required, these were to be provided by the new observatories.
As knowledge of the motions of the planets improved it became possible to make more precise predictions for the future. In 1769 it was predicted that the planet Venus would transit across the face of the sun as viewed from the Earth. It was realised that this rare event would provide a unique opportunity to determine the basic unit of the solar system, the distance from the earth to the sun, (called the Astronomical Unit) provided it could be observed from several stations around the world.
The Royal Society commissioned Captain Cooke to voyage to the Pacific to observe this event from the South Seas and to this end he carried with him an astronomer. It was during this voyage that Cooke annexed Australia. (Drawing by Cooke of transit of Venus).
Observations of the transit were also made by King George III from his new observatory at Kew, built specially for the purpose. The telescope by Short used by George III for this historic observation was presented to Armagh Observatory by Queen Victoria. A clock, by Shelton of London, was used by George III to determine the exact time of the apparition.
The transit of Venus in 1769 was also observed from Ireland using special instruments brought from London for the purpose. They were carried out at Cavan, a townland near Strabane, by Charles Mason (of Mason-Dixon Line fame).
Sir William Herschel, a musician from Germany who settled in England, was probably the greatest astronomer and telescope builder of the 18th century. His telescopes, which were the largest and most powerful of their day, gave him a distinct advantage over his contempories and enabled him to discover many new nebulae and clusters of stars.
Planets, unlike stars, have a visible disc in a large telescope and in 1781 Herschel discovered a new planet which he named Georgium Sidus after George III, his patron. This was the first planet to be discovered since the time of the ancient Greeks and, not surprisingly, its discovery had a profound effect on the public; no longer were the heavens seen to be immutable from ancient times - there were new discoveries to be made in the solar system and beyond. The new planet later came to be known as Uranus.
Richard Robinson, Archbishop of Armagh, was a rich and influential man who embodied the spirit of his age. He was the leader of the established church, the Church of Ireland, and as such received tithes from landowners. He was, however, independently wealthy and by modern standards he would have been a multi-millionaire.
As an educated and enlightened man he resolved to use his wealth and power to found and maintain charitable and educational institutions, particularly in his Primatial City of Armagh. He employed some of the foremost architects of his day: Thomas Cooley, and Francis Johnston, to design buildings and plan his cathedral city.
It is believed that Archbishop Robinson may have been influenced to found an observatory in Armagh by the Reverend J.A. Hamilton, who was to become its first Director. Hamilton, at that time, was Rector of Cookstown, Co. Tyrone, where he had a small private observatory. In 1782 he observed a transit of Mercury and communicated his observations to Maskelyne, the Astronomer Royal for England who presented them to the Royal Society of London. It is reported that Archbishop Robinson was so impressed with Hamilton's observations that he decided to include an Observatory in his plans for Armagh City.
The Observatory, like several of the Archbishop's foundations, was built on a hill so that it could be seen against a natural woodland setting from his new palace. It was designed by Francis Johnston, the city architect, who was responsible for several fine buildings in Dublin; notably, the Chapel Royal and the GPO in O'Connell Street.
The new observatory was the second to be established in Ireland; (the first was Dunsink Observatory near Dublin). It is the oldest scientific institution in Northern Ireland.
In some 17th C observatories, notably Paris (1667), the architectural elegance of the structure was considered more important than its practicality for astronomy This was true to a lesser extent in Wren's design for the Royal Observatory (1675) at Greenwich where, in spite of its grand facade, the structure did not actually impede observations. Normally, at that time, observations were made from either an outside platform or alternatively from inside a large room with tall windows. The instruments were usually portable, with a mounting which simply rested upon a table or the floor and therefore were easily shaken by the movement of people across the room. As instruments increased in size during the 18th and 19th centuries they required more substantial support to avoid vibration.
The buildings of Dunsink (1785) and Armagh (1790) Observatories represent a revolution in observatory design. At Dunsink and Armagh, for the first time, the requirements for the stability of the instruments took priority over aesthetic considerations. Unlike the dome of the King's Observatory, Kew (1768), which is insubstantial and appears almost as an afterthought, the domes at Dunsink and Armagh dominate the structure and form the central theme of the building. In addition the stability of the instruments was guaranteed by placing them on substantial stone pillars brought up from the substrata below the building. At Dunsink these pillars were free standing and not joined to the rest of the building. In this way, any vibrations originating in the main part of the structure, were not transmitted to the instruments. These principles of construction have been employed in most subsequent observatory buildings throughout the world.
Both Dunsink and Armagh Observatories have only sparse ornamentation on their exteriors which is very much in keeping with the new scientific practicality they represented. However, the ornamentation on the exterior at Armagh, restrained as it is, is continued around the building on all sides, quite unlike many 18th C Irish buildings which had a single ornamental facade.
The interior design of Armagh Observatory has a number of unusual features - such as the frequent use of circular motifs; e.g. curved corners to the rooms and bowed chimney breasts. It has one of the best preserved 18th C interiors in N. Ireland.
From the inception of the Archbishop's plan to found an Observatory in Armagh the Reverend J.A. Hamilton, who was to be the first Director, was in touch with one of the leading astronomers of his day, Neville Maskelyne, the Astronomer Royal for England. Maskelyne wrote a letter detailing the requirements for a modern observatory and offered to vet and purchase equipment in London for the Primate's new Observatory.
The principal requirements for serious work on the position of stars were: a transit instrument, a meridian circle and an accurate clock. Whilst, Maskelyne successfully obtained for Armagh two of the finest astronomical clocks available, the two masterpieces by Thomas Earnshaw, he was not so successful with the other instruments.
Dr J A Hamilton, later Rector of Mullabrack, was closely involved in the conception of the Observatory at Armagh and may well have made the initial suggestion to his Archbishop. It was natural that he should be chosen as its first director.
Though generously supported by its founder, the Archbishop, his early death in 1794 resulted in the loss of a number of instruments originally ordered for the Observatory. As a result Hamilton's observations were not as comprehensive as they might have been. Nevertheless he initiated the early series of meterological recordings and observations of stars which paved the way for the future scientific work of the observatory. From the beginning, he expressed a desire to work closely with the astronomer at the other public observatory in Ireland, Dunsink Observatory in Dublin - a cooperation that has continued until the present day.
The need for accurate positions of stars was one of the principal reasons for the establishment of the observatory at Armagh. They were required firstly for navigation and secondly to provide a framework for the measurement of the positions of the planets.
The second reason was scientifically more important as it was only by careful, frequent and accurate observations of the planets, that Newton's law of gravitation, one of the most fundamental laws of physics, could be verified. Indeed, during the 18th century, French astronomers believed they had observed discrepancies in the motions of the planets, which were not accounted for by Newton's laws. English astronomers disputed these findings and were anxious to vindicate the reputation of the great Newton. Whilst in fact the English astronomers on this occasion were proved right - it was the small discrepancies that were discovered in the orbit of the planet, Mercury, in the 19th century, that eventually brought down Newton's theory of gravitation, and lead to Einstein's theory of general relativity.
With the need for accurate positional observations established, how were they to be obtained?
Firstly, we must understand the coordinate systems for stars. In a directly analogous way to latitude and longitude on the earth, astronomers used celestial latitude, (termed declination) and celestial longitude, (termed right ascension). If one imagines the earth's coordinate system, (latitude and longitude), projected onto the celestial sphere, (the sky), one can grasp the basic similarity. Just as we can measure the latitude of a point on the earth's surface by it's distance from the equator, (or 90 degrees minus its distance from the pole), similarly we can determine the declination by measuring the distance of a star from the celestial equator, (or 90 degrees minus the distance from the celestial pole). Also, just as we measure longitude on the earth from an arbritrary zero line, the Greenwich Meridian, we measure right ascension or celestial longitude from an arbrtrarily defined point in the sky called the first point of Aries.
To measure these coordinates for a particular star the simplest and most commonly used instruments were the meridian and transit circles. Both of these instruments consist of a simple refracting telescope which swivels around a horizontal axis which lies exactly east-west. The telescope has a small field of view and is only capable of observing stars in a very narrow strip of the sky. This strip, adjacent to the meridian, passes through: the south and north horizon points, the celestial pole, and the zenith directly overhead. From the time at which the stars cross the meridian astronomers can deduce their right ascension or celestial longitude.
The Troughton Equatorial Telescope
The first major instrument purchased for Armagh Observatory, the telescope made by Troughton of London, is a masterpiece of English instrument-making of the 18th century, only one other instrument of its type exists in the world today. It was purchased by Archbishop Robinson on the recommendation of the Astronomer Royal of England who was very impressed with its novel design.
As explained earlier, the simplest method of measuring the coordinates of stars and planets was to record the time at the instant they crossed the meridian using a transit circle. However the major difficulty with this technique is that observers had only one opportunity per night to make such a measurement - when a star crossed the meridian. Troughton and some of the other instrument makers of his time realized that, if instead of using a horizontal east-west axis, they could mount an instrument on an axis that pointed to the celestial pole, it would be possible to measure the coordinates of a star at any time of the night when that star was visible. This would be particularly valuable if one were trying to obtain a sequence of planetary observations in a poor climate when clouds obscure the sky for much of the night. The astronomers were somewhat dubious that the instrument makers of the day could accomplish the high standard of stability and accuracy, in this more complicated design, than in the simple and well tried meridian and transit circles. Manufacturers, and particularly Troughton, felt they could. To improve stability Troughton used massive stone pillars for support and for rigidity used conical brass tubes to support the central telescope ring.
In the final outcome, although many useful observations were made by this telescope by J A Hamilton, the astronomers were proved right, in that the telescope could not match the accuracy of the simple transit and meridian circle. It was an expensive mistake.
The measurement and keeping of time was, for centuries, one of the most important functions of an observatory. Thus it was necessary to ensure that observatories possessed the most accurate clocks available. In the 18th century the art of making pendulum clocks improved remarkably and one of the most outstanding clock makers at that time was Thomas Earnshaw of London who is known as the father of the chronometer. He was principally known as a watchmaker, and when asked by Nevil Maskelyne if he would make a clock, for Armagh said he did not even know how many wheels were in one. In fact he produced a masterpiece, which is recognised by horologists today as one of the world's most important clocks. It incorporated Earnshaw's new design of escapement and had a number of novel features including its air-tight case (designed to reduce dust and draughts). It was highly praised by Thomas Romney Robinson in the 19th century who at that time believed it to be the most accurate clock in the world. Its purchase price was 100 pounds in 1794 and Earnshaw charged 100 pounds to travel with it to Armagh and set it up in the new Observatory. Partly as a result of the excellent performance of this clock, its maker, Earnshaw was awarded a prize of 3000 pounds by the government. The Observatory also purchased Earnshaw's second clock which was operated at sideral rate with the Troughton Equatorial Telescope.
By the late eighteenth century the basic principles of how to determine latitude and longitude from observations of the Sun and stars were well understood. The latitude, in the northern hemisphere at least, could be easily established by measuring the altitude of the pole star above the horizon, which with a small correction, gave the latitude directly. The determination of longitude is more difficult as it requires comparison of local time with the time at Greenwich. It is from the difference in local time, say midday as determined from the Sun's highest point, from the Greenwich time at that instant, that ships were able to measure their longitude. (The Longitude Problem).
The most serious problem with this proceedure is that it required a ship to carry a clock which could be relied upon to keep accurate Greenwich time for the many months, even years, it took for a voyage around the world. At that time the only reasonably accurate clocks were regulated by pendulums and these were notoriously unstable at sea due to the rocking of the ships on which they were carried. Many ingenious devices were tried to stabilize pendulum clocks but the problem proved intractable and to encourage inventors the British Government, in 1714, offered a prize of 20,000 pounds to the first person to develop a clock which, after a voyage lasting six weeks, allowed the ship's position to be determined better than 30 miles. It is quoted that "the prize at once became the immediate and accessible target of every crank, swindler, fanatic, enthusiast and lunatic in or out of Bedlam" but in addition, for over 50 years, the prize eluded many serious clockmakers as well.
Eventually after several attempts, with ever more complicated machines, half of the prize was awarded to John Harrison, a Yorkshire man, with little or no formal education. The investigating body, the Board of Longitude, were eventually forced into accepting his claim after the intervention of George III, who had taken a personal interest in testing Harrison's time pieces at his own observatory in Kew. Annoyed by the intervention of the King and Parliament on Harrison's behalf, the Board of Longitude denied Harrison the right to the other half of his prize under the pretext that his clock could not be copied. A further prize was announced for the construction of a simple chronometer that could be cheaply made. Two famous London clockmakers vied with each other for this prize; John Arnold, and Thomas Earnshaw the maker of two of the Armagh Observatory clocks. Two clocks by Earnshaw's arch-rival, Arnold, are to be seen at Dunsink Observatory Dublin.
Earnshaw developed a simple type of clockwork chronometer that is to all intents and purposes identical to those made until the middle of this century when quartz clocks became available. It could be mass produced comparatively easily and was within the financial reach of any ship owner. Eventually, after considerable wrangling, when Earnshaw's health was nearly broken, he was awarded \pounds 3000 for his efforts. His appeal to Parliament for compensation was bitterly expressed and in a letter to Dr. J.A. Hamilton Director of Armagh Observatory he requests Hamilton's testimony as to the accuracy of his first clock, Earnshaw No 1. As a result of this evidence, plus that of Maskelyne and others, Parliament finally acceded to Earnshaw's request.
Thomas Romney Robinson, the third director of the Observatory, was, by all accounts, a remarkable man of many interests. He was also a child prodigy - able to read poetry by his third year and to write verse by his fifth. He published a book of poems in his thirteenth year. As a schoolboy his technical and scientific interest developed rapidly and in his poem The Triumph of Commerce, which he wrote in his ninth year, he combined his practical interests with his artistic abilities to praise his friend Mr. W. Richie the founder of the Belfast Shipyards. Robinson continued his brilliant academic career by taking his BA at sixteen years old and becoming a fellow of Trinity College, Dublin at 21.
In 1823 he was appointed director of Armagh Observatory a post which he retained for a total of 59 years and a world record for an observatory director which still stands today. Whilst at Armagh he retained his living as rector of Carrickmacross which supplemented his rather meagre income as Observatory director. He was a brilliant orator and was popular amongst the learned societies of Ulster where his rousing speeches were met with rapturous applause. He was a founder member of the Armagh Natural History and Philosophical Society, President of the Royal Irish Academy in Dublin and President of the British Association for the Advancement of Science. He married twice, first Elizabeth Rambaut, and secondly, Lucy Jane Edgeworth, a sister of Maria Edgeworth the author.
After the death of Archbishop Richard Robinson, (no relation to TRR), in 1794, h