taking. The historical outline which he has there traced forms by far the most valuable portion of that performance, and will for ever remain a proud monument to the depth, to the comprehensiveness, and to the singular versatility of his genius. In the present state of science, however, it has been apprehended that, by dividing so great a work among different hands, something might perhaps be gained, if not in point of reputation to the authors, at least in point of instruction to their readers. This division of labour was, indeed, in some measure rendered necessary (independently of all other considerations) by the important accessions which mathematics and physics have received since D'Alembert's time; by the innumerable improvements which the spirit of mercantile speculation, and the rivalship of commercial nations, have introduced into the mechanical arts; and, above all, by the rapid succession of chemical discoveries which commences with the researches of Black and of Lavoisier. The part of this task which has fallen to my share is certainly, upon the whole, the least splendid in the results which it has to record; but I am not without hopes that this disadvantage may be partly compensated by its closer connexion with (what ought to be the ultimate end of all our pursuits) the intellectual and moral improvement of the species.
I am, at the same time, well aware that, in proportion as this last consideration increases the importance, it adds to the difficulty of my undertaking. It is chiefly in judging of questions "coming home to their business and bosoms," that casual associations lead mankind astray; and of such associations how incalculable is the number arising from false systems of religion, oppressive forms of government, and absurd plans of education! The consequence is, that while the physical and mathematical discoveries of former ages present themselves to the hand of the historian like masses of pure and native gold, the truths which we are here in quest of may be compared to iron, which, although at once the most necessary and the most widely diffused of all the metals, commonly requires a discriminating eye to detect its existence, and a tedious, as well as nice process, to extract it from the ore.
