GEORGE BIDDELL AIRY, M.A., LL.D., D.C.L.,

F.R.S., F.R.A.S., ASTRONOMER ROYAL, ETC. ETC.

AT Alnwick, a town of some historical interest, in Northumberland, the present Astronomer Royal was born on the 27th of July, 1801. His rudimentary education was obtained at private schools at Hereford and Colchester. At the Colchester Grammar School George Biddell Airy received the instruction required as the preliminary training, for a young man about to enter one of our ancient Universities. Having acquitted himself with great credit, he proceeded to Trinity College, Cambridge, in 1819, which he entered as a Sizar, being then eighteen years of age. Mr. Airy followed up his studies with great industry. In 1822, he was elected scholar of Trinity; and in 1823 he took his B.A. degree, winning the distinguished position of Senior Wrangler.

In October, 1824, he was elected a Fellow of Trinity College, and in 1826 he took his M.A. degree. About the same time he had published the first edition of his 'Mathematical Tracts,' in which much was done to make the mathematical education of the University available for Physical Mathematics. This work has passed through several editions, and is believed to have produced a considerable effect on the studies of the University. In 1826 also he was elected to fill the chair of the Professorship which had been founded by Henry Lucas, Esq., M.P. for the University, and rendered illustrious, by its first occupier, in 1663, being Dr. Isaac Barrow, and its second, on his retirement in 1669, the illustrious Newton. Mr. Babbage was, on this occasion, amongst the competitors for the chair.

The Lucasian Professorship had become a perfect sinecure, but Professor Airy resolved to make it of real importance, and in

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1827 he may be said to have re-created the duties, by commencing the delivery of courses of Lectures on Experimental Philosophy, which he continued until 1836. Amongst these, the prelections on the Undulatory Theory of Light are especially remarkable. The principal part of these and other inquiries which engaged the attention of Professor Airy about this time, will be found. in a series of Memoirs, published in the Transactions of the Philosophical Society of Cambridge, of which Society he had been admitted a member in 1823. At this period Professor Airy participated also in the labours of the Board of Longitude. In 1828, being elected Plumian Professor of Astronomy, the management of the then newly-erected Cambridge Observatory devolved upon him. Notwithstanding that he retained the Experimental Lectures, Professor Airy devoted himself most zealously to the business of the Observatory. He devised systems of calculation, and of publication, which were much more complete, and far more serviceable than any which had been previously adopted by any other Observatory. The Astronomical Observations, Cambridge, 1828-1835,' which were published in a clear and simple form, are models of exactness. The systems there set forth have since been adopted at Greenwich, and have been the patterns by which many of the astronomical establishments on the Continent have been guided. Professor Airy superintended the mounting in the Cambridge Observatory of the Equatorial, the Mural Circle, and the Northumberland telescope, which last was especially constructed from his own plans, and exhibits in an eminent degree the remarkable combination of mechanical skill and of optical science, which distinguishes other works emanating from the same mind. In 1828, Mr. Airy was also elected a Fellow of the Astronomical Society, and he became its President in 1835; since which period he has repeatedly filled the chair and sat on the Council. In 1835, the honourable post of Astronomer Royal became vacant by the resignation of Mr. Pond. Lord Auckland was, at that time, First Lord of the Admiralty, and with him rested the responsibility of properly filling this important office. His choice fell on Professor Airy, and the result has proved the correctness of his Lordship's judgment. The appointment has proved of signal advantage to science, and has greatly added to our national reputation.

In 1836 Mr. Airy was elected a Fellow of the Royal Society. Mr. Airy was one of the original members of the Senate of the

University of London. He did not, however, hold that appointment very long. In subsequent years he was consulted with reference to the establishment of Universities in our Australian Colonies.

As Astronomer Royal, Mr. Airy has distinguished himself by giving the utmost precision to the proceedings in the Observatory at Greenwich, and by publishing the yearly observations with a completeness of reduction and a regularity which never were before attempted. The historical associations of Greenwich Observatory have imposed upon that Institution some characteristic features. At the same time as those have been preserved, Professor Airy has constantly introduced such new instruments, and modes of calculation, as maintained its position as one of the first Astronomical Institutions. The Altazimuth, the Transit Circle, the Reflex Zenith Tube, and the large Equatorial, were all constructed from Professor Airy's plans, and erected under his superintendence. These may be said to be the first-class Equatorial especially the finest instruments of their kind.

In the Cambridge Observatory, Mr. Airy first introduced the system of making an annual printed Report on the state of the Observatory, which system has been continued and extended at the Greenwich Observatory; till the "Reports of the Astronomer Royal to the Board of Visitors" form, perhaps, one of the most complete series of "Annals" that are to be found. This system has been copied and adopted with great advantage, not in Observatories only, but also in other institutions.

The observations of Groombridge, Catton, and Fallows, had long remained in a useless condition; these Mr. Airy computed, edited, and published. The Greenwich observations of planets and the moon from 1750 were useless to the world; these were also reduced and published by the unwearying industry of the new Astronomer Royal. Well might Admiral Smyth say of these, they were "an immense magazine of dormant facts, contained in the annals of the Royal Observatory," which now "are rendered available to astronomical use," and from which "we may perhaps date a new epoch in planetary astronomy."

In 1842, Mr. Airy made a journey to Turin, expressly for observation of the Total Solar Eclipse; and was one of the first discoverers of the Red Prominences which have since attracted so much attention. In 1851, he made a journey to Gottenburg, in

Sweden, for the same purpose; the observations collected on this occasion were very important. In 1860, he organized an expedition of astronomers to Spain for a similar purpose; on this occasion the Admiralty placed under his direction their large steamer 'Himalaya.' The greater part of the observations then made have been made public (especially the important photographic operations of Mr. De La Rue); somé few, however, yet remain to be published.

Mr. Airy, shortly after his appointment to the Greenwich Observatory, proposed to the Government to attach to it a Magnetical and Meteorological Observatory. This was completed. about 1838. Mr. Airy entered vigorously into the system of co-operative observations at many widely-distributed stations, commenced about the end of 1840. It was at his instance that the Government offered a reward for the invention of methods for the self-registration of magnetical and meteorological instruments, which was adjudged to Mr. Charles Brooke. Mr. Brooke erected the apparatus which is still in use at the Royal Observatory. Photography is here used to a great extent. The whole of the magnetical and meteorological establishment is in the highest state of efficiency.

Within a few years an apparatus has been attached to it, connected with two telegraph wires, each about ten miles long, for the continual registration of the spontaneous earth-currents first observed by practical telegraphers.

Professor Airy introduced from America the system of chronographic register, by galvanic currents, of transits and other observations of time.

In 1838, Professor Airy was consulted by the Government on the important question of the disturbances produced on the compass-needles in iron-built ships. An extensive series of experiments were made; and from these a theory was developed which introduced a system of mechanical correction, which has been universally adopted.* With the extension of the use of iron in ships, the question has become of still greater interest, and the utmost attention has been directed to the examination of all the conditions of disturbance. Although some improvements in the adjustments have been the result, still the principles arrived at

*See Phil. Transactions for 1839.