were at an end.” He had thirteen children, of whom only three survived him; one of them, John Albert Euler, was known as a mathematician. Footnote 8: We suspect some mistake in this account, which is constantly given. A very surprising story ought to be consistent: now it is difficult to believe that any series which was actually employed in practice (and people do not sum series to fifty places for amusement) would converge so quickly, as to give fifty places in seventeen terms. The well-known series for the base of Napier’s logarithms is called a rapidly converging series, and gives about fifteen places in seventeen terms. We cannot help thinking, either that Euler settled one disputed term only, or that there is some mistake about the number of figures. Footnote 9: Il cessa de calculer et de vivre.—CONDORCET. Of the scientific character of Euler it is impossible to speak in detail, since even the _resumé_ of M. Condorcet, which is much longer than any account we can here insert, is meagre in the extreme; and we imagine that the reader would form no idea whatsoever of the man we are describing, from any brief enumeration of discoveries for which we should be able to allow room. In more than fifty years of incessant thought, Euler wrote thirty separate works and more than seven hundred memoirs: which could not altogether be contained in forty large quarto volumes. These writings embrace every existing branch of mathematics, and almost every conceivable application of them, to such an extent, that there is no one among mathematicians, past or present, who can be placed near to Euler in the enormous variety of the subjects which he treated. And the contents of these volumes are without exception the original fruit of his own brain; seeing that he left no subject as he found it. He is not a diffuse writer, except in giving a large number of examples, and this renders him in some respects the most instructive of all writers. His works are full of the most original thoughts developed in the most original manner; so that they have been a mine of information for his successors, which is even now far from being exhausted. Let a student be employed upon any subject connected with mathematics, however remotely, and he has discovered but little if he has not found out that Euler was there before him. Of all mathematical writers, Euler is one of the most simple, and this in a manner which renders his writings not by any means a sound preparation for future investigations. Difficulties seem to have disappeared in the progress, or never to have been encountered; and the student is rather made to feel that Euler could take him anywhere, than furnished with the means of providing for himself, when his guide shall have left him. Hence the writings of others, in every way inferior to Euler in elegance and simplicity, are to be preferred, and have been preferred, for the formation of mathematical power.