the systematic relief which he obtained by short holiday expeditions whenever he found himself worn with work, and his keen interest in history, poetry, classics, antiquities, engineering, and other subjects not immediately connected with his profession, had combined to produce this result.  And in leaving office, he had no idea of leaving off work; his resignation of office merely meant for him a change of work.  It is needless to say that his interest in the welfare and progress of the Observatory was as keen as ever; his advice was always at the service of his successor, and his appointment as Visitor a year or two after his resignation gave him an official position with regard to the Observatory which he much valued.  The White House, which was to be his home for the rest of his life, is just outside one of the upper gates of the Park, and about a quarter of a mile from the Observatory.  Here he resided with his two unmarried daughters.  The house suited him well and he was very comfortable there:  he preferred to live in the neighbourhood with which he was so familiar and in which he was so well known, rather than to remove to a distance.  His daily habits of life were but little altered:  he worked steadily as formerly, took his daily walk on Blackheath, made frequent visits to Playford, and occasional expeditions to the Cumberland Lakes and elsewhere.

The work to which he chiefly devoted himself in his retirement was the completion of his Numerical Lunar Theory.  This was a vast work, involving the subtlest considerations of principle, very long and elaborate mathematical investigations of a high order, and an enormous amount of arithmetical computation.  The issue of it was unfortunate:  he concluded that there was an error in some of the early work, which vitiated the results obtained:  and although the whole process was published, and was left in such a state that it would be a comparatively simple task for a future astronomer to correct and complete it, yet it was not permitted to the original author of it to do this.  To avoid the necessity of frequent reference to this work in the history of Airy’s remaining years, it will be convenient to summarize it here.  It was commenced in 1872:  “On Feb. 23rd in this year I first (privately) formed the notion of preparing a Numerical Lunar Theory by substituting Delaunay’s numbers in the proper Equations and seeing what would come of it.”  From this time forward till his power to continue it absolutely failed, he pursued the subject with his usual tenacity of purpose.  During his tenure of office every available opportunity was seized for making progress with his Lunar Theory, and in every Report to the Visitors a careful statement was inserted of the state in which it then stood.  And, after his resignation of office, it formed the bulk of his occupation.  In 1873 the Theory was formed, and by 1874 it was so far advanced that he published in the Monthly Notices of the Royal Astronomical Society