PREFACE.

THE reflecting portion of mankind has ever felt desirous of becoming acquainted with the origin, progress, habits, and peculiarities of those whom the powers of genius may have raised above the plane of intellectual equality; but neither the nature of the information, nor the extent of the detail that may be necessary to satisfy so laudable a curiosity, can ever be estimated by any common standard, since it is not in our nature to contemplate an object of admiration, but with reference to our own predilections and sympathies; and hence every reader will form a scale for himself, according to the degree of interest he may feel for the particular character under review. The Poetical enthusiast, who could not sufficiently express his gratitude on being told that Milton wore shoe-buckles, would very probably have not given four farthings,' as Gray says, to know that the shoes of Davy were tanned by catechu; and yet if the relative value of this information were fairly estimated, it must be admitted that the former is a matter of barren curiosity, the latter a fact of some practical utility. In a word, we very naturally connect the man with his works, and we care not to extend our acquaintance with the one, but in proportion as we have derived pleasure from the other.

In like manner, very different estimates will be formed of the degree of praise due to a distinguished philosopher, because the few who are deeply imbued with a knowledge of the science he may have adorned and enlightened

must not only appreciate the value of his labours, but understand the difficulties which opposed the accomplishment of them, before they can arrive at a sound decision upon the question; and here again the judgment of the most scientific may be unfortunately warped; it may be corrupted by secret passions or sinister influences; be distorted by the prejudices of education and habit, or unduly biassed by invincible prepossessions.

No man ever soared, like an eagle, to the pinnacle of fame, without exciting the envy and perhaps the hatred of those who could only crawl up half way; while, on the other hand, where no rivalry can exist, the splendour of such an ascent will captivate the bystander, and by exciting intemperate triumph and unqualified admiration, change without diminishing the sources of erroneous judgment, and substitute adulation for calumny. Under such circumstances, an allusion even to the common frailties of genius becomes offensive; the biographer is called upon for the delineation of a perfect man; but the world is satisfied with nothing short of a faultless monster;' and yet, while they would impose upon him the same restraint as Queen Elizabeth laid upon her artist-to execute a portrait without a single shadow, they little imagine how completely they obscure the features of their idol, by the haze of incense in which they continually envelope it. These are evils against which a future historian will not have to contend; for time tries the characters of men, as the furnace assays the quality of metals, by disengaging the impurities, dissipating the superficial irridescence, and leaving the sterling gold bright

and pure.

Nor can the extent of our obligations to a philosopher be appreciated until time shall have shown the various important purposes to which his discoveries may administer. The names of Mayow and Hales might have been lost in the stream of discovery, had not the results of Priestley and Lavoisier shown the value and importance of their statical experiments on the chemical relations of air to other substances. The discoveries of Dr. Black on the subject of latent heat could never have obtained that celebrity they now enjoy, had

not Mr. Watt availed himself of their application for the improvement of the steam-engine; and the views of Sir H. Davy respecting the true nature of chlorine become daily more important from the discovery of new elements of an analogous nature. In future ages, the metals of the alkalies and earths may admit of applications, and open new avenues of knowledge, of which at present we can form no idea; but it is obvious that, in the page of history, his name will gather fame in proportion as such discoveries unfold themselves.

It must be admitted, that such considerations may furnish an argument against the propriety of writing the life of a contemporaneous philosopher; and yet I will never admit, with Mr. Babbage, that "the volume of his biography should be sealed, until the warm feelings of surviving kindred and admiring friends shall be cold as the grave, from which remembrance vainly recalls his cherished form, invested with all the life and energy of recent existence."

Is it not possible that the errors of partiality, which have so frequently been charged upon the writer on these occasions, may often be ascribed, with greater truth and justice, to the prejudices of the reader that, after all, the distortion might not have existed in the portrait itself, but in the optics of the observer? Such an opinion, however, even were it true, carries along with it no consolation to the biographer; for I know of no method by which the picture can be adapted to the focus of every eye.

If, however, contemporaneous biography has its difficulties and impediments, so has it also its advantages. Dr. Johnson has remarked, in his Life of Addison, that " History may be formed from permanent monuments and records; but Lives can only be written from personal knowledge, which is growing every day less, and in a short time is lost for ever. The delicate features of the mind, the nice discriminations of character, and the minute peculiarities of conduct, are soon obliterated."

I did not enter upon this arduous and delicate task, without a distinct conception of the various difficulties which would necessarily oppose its

accomplishment. I well knew that the biographer of Davy must hold himself prepared for the dissatisfaction of one party at the commendations he might bestow, and for the displeasure of the other, at the penury of his praise, or the asperity of his criticism.

After great labour and much anxiety, I have at length completed the work; and in giving it to the world, I shall apply to myself the words of Swift" I have the ambition to wish, at least, that both parties may think me in the right; but if that is not to be hoped for, my next wish should be, that both might think me in the wrong, which I would understand as an ample justification of myself, and a sure ground to believe that I have proceeded, at least, with impartiality, and perhaps even with truth."

It is certainly due to myself, and perhaps to the world, to state the circumstances by which I was induced to undertake a work requiring for its completion a freedom from anxiety, and an extent of research, scarcely compatible with the occupations of a laborious profession; and which, I may add, has been wholly composed during night, in hours stolen from sleep. Very shortly after the death of Sir Humphry Davy, an account of his life, written by no friendly hand, nor honest chronicler,' was submitted for my judgment by a Journalist who had intended to insert it in his paper. At my request, it was committed to the flames; but not until I had promised to supply the loss by another memoir. The sketches by which I redeemed this pledge were published in a weekly journal-THE SPECTATOR; and they have since been copied into various other works, sometimes with, but frequently without any acknowledgment. They constitute the greater part of the life which was printed in the Annual Obituary for 1829; and they form the introduction to an edition of his "Last Days," lately published in America.

I was soon recognised as the writer of these Sketches; and the leading publishers of the day urged me to undertake a more extended work. To these solicitations I returned a direct refusal: I even declined entering upon any conversation on the occasion; feeling that the wishes of Lady Davy, at

that time on the Continent, ought in the very first instance to be consulted on the subject. Had not the common courtesy of society required such a mark of attention, the wish expressed by Sir Humphry in his Will would have rendered it an imperative duty. On her arrival in London, in consequence of a letter she had addressed to Mr. Murray, I requested an interview with her Ladyship, from whom I received not only an unqualified permission to become the biographer of her illustrious husband, but also the several documents which are published with acknowledgement in these memoirs. I still felt that Dr. Davy might desire to accomplish the task of recording the scientific services of his distinguished brother; and, had that been the case, I should most undoubtedly have retired, without the least hesitation or reluctance; but I was assured by those who were best calculated to form an opinion upon this point, for he was himself absent from England, -that motives of delicacy which it was easy to appreciate, would at once lead him to decline an undertaking embarrassed with so many personal considerations. The task, however, of collating the various works of Sir H. Davy, and of enriching them by notes derived from his own knowledge of the circumstances under which they were written, I do hope will be accomplished by one who is so well calculated to heighten the interest, and to increase the value of labours of such infinite importance to science, and to the best interests of mankind.

The engraving which adorns the volume is from a painting by Sir Thomas Lawrence, presented to the Royal Society by Lady Davy; and I beg the Council of that learned body to accept my thanks for the permission they so readily granted for its being engraved. It is one of the happiest efforts of the distinguished Artist, and is the only portrait I have seen in which his features are happily animated with the expressions of the poet, and whose eye is bent to pursue the flights of his imagination through unexplored regions.

I must also embrace this opportunity of publicly expressing my thanks to the Managers of the Royal Institution, who, in the most handsome manner,

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