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I do not remember how my acquaintance with Colonel Colby began.

We both were members of the Board of Longitude, which was dissolved in 1829 (I think), and it is probable that our intimacy commenced then.

It could not be later when I received a call from him at Cambridge (I suppose at the Observatory), when he was on his way to Ely, upon business of the Survey. Subsequently I saw him very frequently, and on some occasions which were almost official; in mspection of Ramsden's Sector at the Tower; in preparing the Sector with which my name is connected; in arranging Tidal Observations; in preparing for determination of the Longitude of Valencia; twice or oftener in examining the System of the Phoenix Park Office; and at many other times.

At one of my Irish visits, I had the happiness of enjoying the hospitality of Knock Maroon Lodge, and in later years, when Colonel Colby was for a long time fixed in London, I and my family had the gratification of receiving him very often at our Sunday dinner at Greenwich. We can all bear testimony to his kind and social disposition; his appearance was always a source of friendly pleasure to us.

I was often struck with the peculiar adaptation of Colonel Colby's talents and habits to the great work which he directed, and the great

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system which he principally created. With the scientific geodetic problem before him he was familiar.

On the grand points of execution, such as the large-scale triangulation (I may well use that epithet for a triangulation which described the length of Ireland in three steps, and its breadth in two), he was clear in his own judgment, and decided in his provisions for carrying them out.

On the detailed points, such as local surveys, mapping, engraving, engagement of local assistants, &c., of which the execution naturally fell to other persons of all ranks, he was most precise in arrangements on the broad scale, and at proper times most exact in watching their general success.

The order of his offices was admirable.

His attention to the accuracy of instruments of every kind-personally for those used in the grand survey-systematically for those used in the details -was very great. And all this devotion of himself to his great work appeared to be wholly unselfish.

I never heard a word from him which implied that he was looking abroad for personal glory, or for any expression except the recognition of his results-as producing a scientific survey superior to any that had ever been made, and a cadastral mapping to which no other, I believe, can be compared. He was most liberal in his praises of the officers

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subordinate to himself by whom the scientific details were more immediately managed.

I hope that these short statements may assist to perpetuate an impression which, as I know, was felt by others as well as myself.

I am,

My dear Madam,

Yours very faithfully,

Mrs. General Colby.

G. B. AIRY.

MEMOIR OF THE LATE MAJOR-GENERAL

COLBY.

WHEN we turn from the contemplation of great actions, either in civil or military history, to an investigation of the causes which have led to their performance, we are too often doomed to experience the disappointment of finding the motive-springs of brilliant acts, in themselves, mean and sordid. Were it, however, the object of this memoir to describe the moral rather than the intellectual man, the character of General Colby might be subjected without danger to the ordeal of such an inquiry, as few men were so free from the impulses either of avarice or of ambition. Affecting no contempt for the pecuniary remuneration of his services, and rightly considering the labourer worthy of his hire, he was always willing to apply what he derived from the service to its advancement; and hence it was that neither he nor any of his officers or assistants ever thought of calculating personal expense when it became necessary to push forward the work confided to their care. If, therefore, General Colby considered that officers of the Survey should

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be well paid, he was influenced, not by a spirit of accumulation, but by a desire to afford them the means of moving and acting with energy and effect under all circumstances. In like manner, though, in his early life, he was not indifferent to honorary rewards or distinctions, especially those of a scientific character, it cannot be said that at any time the desire of obtaining them exercised a powerful influence on his mind; and when, in later years, his affections became domestic in their tone, and were centered in his home and linked to his wife and children, he appeared absolutely to despise them.

A contempt for worldly honours, and an indifference to wealth, are often cited as characteristics of a great mind; and yet qualities so undoubtedly noble are on the whole more suited to the quiet philosopher than to the active man of business. A sense of duty will impel a man to do and to suffer much, and the love of a particular pursuit will render him regardless of difficulties, and blind to danger, just as the botanist will seek the rare plant, or the entomologist the wished-for insect, in the deadly marsh, the impervious forest, or in the burning desert; but when so much has been done and suffered, he who was unmoved by the apprehension of corporeal pain and danger will shrink from the mental torture of other men's criticisms, unless urged forward to the publication of his labours by the hope of attaining either wealth or honours for the present, or an undying fame for the future. The want of this stimulating and supporting prin