matters or correspondence.

(5) The letters to his wife are very numerous. They were written during his occasional absences from home on business or for relaxation. On these occasions he rarely let a day pass without writing to his wife, and sometimes he wrote twice on the same day. They are full of energy and interest and many extracts from them are inserted in this history. A great deal of the personal history is taken from them.

(6) All correspondence in any way connected with business during the time that he was Astronomer Royal is to be found at the Royal Observatory. It is all bound and arranged in the most perfect order, and any letter throughout this time can be found with the greatest ease. It is very bulky, and much of it is, in a historical sense, very interesting. It was no doubt mainly from this correspondence that the Autobiography, which so far as related to the Greenwich part of it was almost entirely a business history, was compiled.

The history of the early part of his life was written in great detail and contained a large quantity of family matter which was evidently not intended for publication. This part of the Autobiography has been compressed. The history of the latter part of his life was not written by himself at all, and has been compiled from his Journal and other sources. In both these cases, and occasionally in short paragraphs throughout the narrative, it has been found convenient to write the history in the third person.

2, THE CIRCUS, GREENWICH.

NOTE.

The Syndics of the Cambridge University Press desire to express their thanks to Messrs Macmillan & Co. for their courteous permission to use in this work the steel engraving of Sir George Biddell Airy published in Nature on October 31, 1878.

TABLE OF CONTENTS.

CHAPTER I.

Personal Sketch of George Biddell Airy

CHAPTER II.

From his birth to his taking his B.A. Degree at Cambridge

CHAPTER III.

At Trinity College, Cambridge, from his taking his B.A. Degree to his taking charge of the Cambridge Observatory as Plumian Professor

CHAPTER IV.

At Cambridge Observatory, from his taking charge of the Cambridge
Observatory to his residence at Greenwich Observatory as Astronomer
Royal

CHAPTER V.

At Greenwich Observatory, 1836-1846

CHAPTER VI.

At Greenwich Observatory, 1846-1856

CHAPTER VII.

At Greenwich Observatory, 1856-1866

CHAPTER VIII.

At Greenwich Observatory, 1866-1876

CHAPTER IX.

At Greenwich Observatory, from January 1st, 1876, to his resignation of office on August 15th, 1881

CHAPTER X.

At the White House, Greenwich, from his resignation of office on
August 15th, 1881, to his death on January 2nd, 1892

APPENDIX.

List of Printed Papers by G.B. Airy, and List of Books written by
G.B. Airy

INDEX.

CHAPTER I.

PERSONAL SKETCH OF GEORGE BIDDELL AIRY.

The history of Airy's life, and especially the history of his life's work, is given in the chapters that follow. But it is felt that the present Memoir would be incomplete without a reference to those personal characteristics upon which the work of his life hinged and which can only be very faintly gathered from his Autobiography.

He was of medium stature and not powerfully built: as he advanced in years he stooped a good deal. His hands were large-boned and well-formed. His constitution was remarkably sound. At no period in his life does he seem to have taken the least interest in athletic sports or competitions, but he was a very active pedestrian and could endure a great deal of fatigue. He was by no means wanting in physical courage, and on various occasions, especially in boating expeditions, he ran considerable risks. In debate and controversy he had great self-reliance, and was absolutely fearless. His eye-sight was peculiar, and required correction by spectacles the lenses of which were ground to peculiar curves according to formulae which he himself investigated: with these spectacles he saw extremely well, and he commonly carried three pairs, adapted to different distances: he took great interest in the changes that took place in his eye-sight, and wrote several Papers on the subject. In his later years he became somewhat deaf, but not to the extent of serious personal inconvenience.

The ruling feature of his character was undoubtedly Order. From the time that he went up to Cambridge to the end of his life his system of order was strictly maintained. He wrote his autobiography up to date soon after he had taken his degree, and made his first will as soon as he had any money to leave. His accounts were perfectly kept by double entry throughout his life, and he valued extremely the order of book-keeping: this facility of keeping accounts was very useful to him. He seems not to have destroyed a document of any kind whatever: counterfoils of old cheque-books, notes for tradesmen, circulars, bills, and correspondence of all sorts were carefully preserved in the most complete order from the time that he went to Cambridge; and a huge mass they formed. To a high appreciation of order he attributed in a great degree his command of mathematics, and sometimes spoke of mathematics as nothing more than a system of order carried to a considerable extent. In everything he was methodical and orderly, and he had the greatest dread of disorder creeping into the routine work of the Observatory, even in the smallest matters. As an example, he spent a whole afternoon in writing the word "Empty" on large cards, to be nailed upon a great number of empty packing boxes, because he noticed a little confusion arising from their getting mixed with other boxes containing different articles; and an assistant could not be spared for this work without withdrawing him from his appointed duties. His arrangement of the Observatory correspondence was excellent and elaborate: probably no papers are more easy of reference than those arranged on his system. His strict habits of order made him insist very much upon detail in his business with others, and the rigid discipline arising out of his system of order made his rule irksome to such of his subordinates as did not conform readily to it: but the efficiency of the Observatory unquestionably depended mainly upon it. As his powers failed with age the ruling passion for order assumed a greater prominence; and in his last days he seemed to be more anxious to put letters which he received into their proper place for reference than even to master their contents.

His nature was eminently practical, and any subject which had a distinctly practical object, and could be advanced by mathematical investigation, possessed interest for him. And his dislike of mere theoretical problems and investigations was proportionately great. He was continually at war with some of the resident Cambridge mathematicians on this subject. Year after year he criticised the Senate