Euler is to be measured by the assistance which he gave to his immediate successors, and here it is well known that he paved the way for the research of others in a more effectual manner than any of his contemporaries. The incessant repetition of his name in later authors is sufficient authority for this assertion. His writings are the first in which the modern analysis is uniformly the instrument of investigation. His predecessors, James and John Bernouilli, had perhaps the largest share in bringing the infinitesimal analysis of Newton and Leibnitz to the state of power required for extensive application. To Euler (besides important extensions) belongs the distinct merit of showing how to apply it to physical investigations, in conjunction with D'Alembert, who ran a splendid and contemporary career of a similar character in this respect. But though it would be perhaps admitted that there are individual results of the latter which exceed anything done by the former, in generality of application, there is no comparison whatsoever between the extent of the labours of the two.

Euler was a man of a simple, reserved, and benevolent mind; with a strong sense of devotion, and a decided religious habit, according to the Calvinism of the Established Church of his country. At the court of Frederic, he himself conducted the devotions of his family every evening; a practice which then and there implied much moral courage, and insensibility to ridicule. But he possessed humour, for when he was asked to calculate the horoscope of one of the Russian princes, he quietly suggested that it was the official duty of the astronomer, and imposed the duty upon a colleague, who doubtless did not feel very much flattered by the application.

There are few men whom the usual biographical formulæ as to moral character and habits would

better fit than Euler, according to every account which has appeared of him. But such praises are no distinction; and it will be more to the purpose to state that the only occasion in which he was betrayed into printing a word which his eulogists have regretted, was in the dispute between Maupertuis and himself against others on the principle known by the name of least action, one of the warmest and most angry discussions which ever took place.

Perhaps it is to the quiet abstraction of his life that he owed the perpetuity of his tenure of investigation. Many eminent mathematical discoverers have run the brilliant part of their career while comparatively young. Euler" ceased to calculate and to live" at once. But it may be that this was a part of his natural constitution, and a distinct feature of his mind. The nature of his writings rather confirms the latter supposition. There is the same difference between them and those of others, that there is between conversation and oratory. He seems to be moving in his natural element, where others are swimming for their lives.

The best works of Euler for a young mathematician to read, in order to get an idea of his style and methods, are the Analysis Infinitorum,' and the "Treatise on the Integral Calculus.'

SAMUEL JOHNSON was born September 18, 1709, in the city of Lichfield, where his father, a man well respected for sense and learning, carried on the trade of a bookseller, and realised an independence, which he afterwards lost by an unsuccessful speculation. His mother also possessed a strong understanding. From these parents Johnson derived a powerful body, and a mind of uncommon force and compass. Unfortunately both mind and body were tainted by disease: the former by a melancholy, of which he Isaid that it had "made him mad all his life-at least not sober;" the latter by that scrofulous disorder called the king's evil, for which, in compliance with a popular superstition, recommended by the Jacobite principles of his family, he was touched by Queen Anne. By this disease he lost the sight of one eye, and the other was considerably injured: a calamity which combined with constitutional indo

lence to prevent his joining in the active sports of his school-fellows. Tardy in the performance of his appointed tasks, he mastered them with rapidity at last, and he early displayed great fondness for miscellaneous reading, and a remarkably retentive memory. After passing through several country schools, and spending near two years in a sort of busy idleness at home, he went to Pembroke College, Oxford, about the age of sixteen. There he made himself more remarkable by wit and humour, and negligence of college discipline, than by his labours for University distinction: his translation of Pope's Messiah into Latin hexameters was the only exercise on which he bestowed much pains, or by which he obtained much credit. But his high spirits, unless the recollections of his earlier years were tinctured by his habitual despondency, were but the cloak of a troubled mind. "Ah! Sir," he said to Boswell, "I was mad and violent. It was bitterness which they mistook for frolic. I was miserably poor, and I thought to fight my way by my literature and my wit, so I disregarded all power and all authority." His poverty during this period was indeed extreme; and the scanty remittances by which he was supported, in much humiliation and inconvenience, were altogether stopped at last by his father's insolvency. He had the mortification to be compelled to quit Oxford in the autumn of 1731, after three years' residence, without taking a degree; and his father's death in the December following threw him on the world, with twenty pounds in his pocket.

He first attempted to gain a livelihood in the capacity of usher to a school at Market-Bosworth, in Leicestershire. For that laborious and dreary task he was eminently unfit, except by talent and learning, and he soon quitted a situation which he ever remembered with a degree of aversion amount

ng to horror. After his marriage he tried the experiment of keeping a boarding-house near Lichfield, as principal, with little better success.

From

Bosworth he went to Birmingham, in 1733, where he composed his first work, a translation of the Jesuit Lobo's Voyage to Abyssinia. He gained several kind and useful acquaintance in the latter town, among whom was Mr. Porter, a mercer, whose widow he married in 1735. She was double his age, and possessed neither beauty, fortune, nor attractive manners, yet she inspired him with an affection which endured, unchilled by the trials of poverty, unchanged by her death, even to the end of his own life, as his private records fully testify. She died in 1752.

In March, 1737, Johnson set out for the metropolis, in hopes of mending his fortunes, as a man of letters, and especially of bringing on the stage his tragedy of Irene. It was long before his desires were gratified in either respect. Irene was not performed till 1749, when his friend and former pupil, Garrick, had the management of Drury-Lane. Garrick's zeal carried it through nine nights, so that the author, in addition to one hundred pounds from Dodsley for the copyright, had the profit of three nights' performance, according to the mode of payment then in use. The play however, though bearing the stamp of a vigorous and elevated mind, and by no means wanting in poetical merit, was unfit for acting, through its want of pathos and dramatic effect and Johnson perhaps perceived his deficiency in these qualities, for he never again wrote for the stage. Garrick said of his friend, that he had neither the faculty to produce, nor the sensibility to receive the impressions of tragedy: and his annotations upon Shakspeare confirm this judgment.

His first employment after his arrival in London