504
first in Europe or the world. The renovation which
he effected was, indeed, most radically complete.
The whole of the old trash was thrown aside, and
its place supplied by new instruments, constructed
on the most improved principles by the most cele-
brated artists both in this country and on the Con-
tinent; while its absolute amount was increased
tenfold, and adapted in the happiest manner to the
present advanced state of science. His perseverance
and enthusiasm in this respect were indeed boundless;
and as his predecessors were not experimentalists,
in the same sense in which he was, and had made
little or no effort to accommodate the apparatus to
the progress of science, or even to repair the wear
and tear of time, he had the whole to create, in the
same way as if the class had only been founded when
he was first promoted to the chair. By his own
continued and admirably-directed efforts, aided by
the liberality of the patrons, who generously made
him several grants in furtherance of the object which
he had so much at heart—and also by very consider-
able pecuniary sacrifices upon his own part, for which
he has never as yet got the credit that is so justly
due to him—he at length succeeded in furnishing
the apparatus-room in the manner in which it may
now be seen by any one who chooses to visit it, and
thus conferred upon the university a benefit for which
it ought to be for ever grateful to his memory. This
may sound strange in the ears of those who have
been accustomed to hear it said, as it has often been,
most falsely, that Sir John Leslie was a bad experi-
menter. The truth is, that of all his great and varied
gifts, none was more remarkable than the delicacy
and success with which he performed the most diffi-
cult experiments, excepting perhaps his intuitive
sagacity in instantly detecting the cause of an acci-
dental failure; and it is a known fact, that, after he
had discovered and communicated to the world his
celebrated process of artificial congelation, particu-
larly as applied to the freezing of mercury, some of
the first men of science in London failed of performing
it, till the discoverer himself, happening to be on
the spot personally, showed them wherein consisted
the fault of their manipulation, and at once performed
the experiment which had previously baffled all their
efforts. It is equally well known to those who
were acquainted with him, that the most elegant
in form as well as the most delicate in operation of
the beautiful instruments invented by himself were
constructed by his own hand, and that this, to him
most agreeable employment, constituted the recrea-
tion of his leisure hours. The apparatus-room,
indeed, contains many specimens of his workmanship
in this line, and they are of such a description as
would not do any discredit to the most practised and
skilful artist. To his immediate successor his acqui-
sitions and his labours will therefore be of incalcu-
lable importance; but the merit which really belongs
to him can only be duly estimated by those who
know what he found when he became professor of
natural philosophy, and can compare it with the
treasures which he has left behind him."1
1 Some further particulars respecting his various talents and
acquirements may be gathered from the following notice which
appeared in the Edinburgh Courant, and seems to be the pro-
duction of one qualified in more ways than one to speak upon the
subject:—" Sir John Leslie has been for many years known in
this country, and over all Europe, as one of the most eminent
characters of the age. As a mathematician and philosopher—as
a profound and accomplished scholar—as a proficient in general
literature, and in history and many other branches of know-
ledge—he had few rivals. But it was for mathematical science
and its kindred studies that he discovered, at a very early
period, a decided predilection; and it is in the successful illus-
tration of scientific truth and of all the complicated phenomena
of physics that his great reputation has been acquired. In
LEVEN, EARL OF.    See LESLIE (ALEXANDER).
LEYDEN, JOHN, a man of singularly varied genius
and accomplishment, was born on the 8th of Sep-
tember, 1775, at Denholm, a village on the banks
of the Teviot, in the parish of Cavers and county of
Roxburgh. His parents were John Leyden and Isa-
bella Scott, who had three sons and two daughters
younger than himself. His ancestors in both lines
had been farmers on the estate of Cavers for several
generations; but his father, though skilful in rural
affairs, declined to engage on his own account in
the same occupation, thinking even the fortunate
pursuit of gain a poor compensation for the anxiety
that attends it. About a year after the birth of their
first child, he removed to Henlawshiel on the farm
of Nether Tofts, which was then occupied by Andrew
Blythe, his wife's uncle, whom he first served as
shepherd, and subsequently as overseer, his master
having had the misfortune to lose his sight. The
these pursuits he was eminently qualified to excel by the great
original powers of his mind, which were further stimulated by
an ardent enthusiasm, and an early desire of distinction among
the illustrious names of his day. Along with a profound
knowledge of his subject, he possessed great inventive powers,
which not only enabled him to sound the depths of science, but
to expound its important problems with a simplicity and elegance
rarely equalled. In making his way through the intricacies of
physical research, his severe judgment guided him in the right
path; and hence his demonstrations always afford a striking
and beautiful display of pure reason, without any tendency to
that spirit of metaphysical subtlety which occasionally per-
plexes the speculations of Laplace, Legendre, with others of
the continental philosophers; and it is worthy of remark that,
along with the penetrating force of his judgment, he carried
into those studies that taste and fancy—that predilection for
the beautiful—which may be recognized in all his speculations,
whether in literature or in science. His taste in geometry was
founded on the purest models of Grecian philosophy; he de-
lighted to expound to his pupils the simplicity and elegance of
the demonstrations by the great masters of antiquity; he com-
mended them to their imitation, and expatiated on the subject
in a manner well fitted to inspire a kindred enthusiasm; so
that we might have fancied that he was dilating, not on the
merits of a mathematical problem, but on some of those beauti-
ful forms and classic models of ancient art which have been
the wonder of all succeeding times. Nor was this admiration
of ancient geometry a mere pedantic or barren speculation.
The great philosopher of whom we are speaking carried his
principles into practice, and applied the abstract properties of
figures with the happiest success to experimental philosophy ;
many branches of which he greatly extended by his discover-
ies; and in all of them he developed the most original views,
which may yet be traced to important results. The range of
his studies was amazingly extensive; and he had accumulated
vast stores of knowledge, especially on scientific subjects. He
was deeply versed in the history of science, which he had
traced from its earliest dawnings in the times of Greece and
Rome, through all the subsequent vicissitudes which it expe-
rienced during the dark ages of barbarism, till it was revived
by the Arabians in the East, and was afterwards improved and
perfected by the more brilliant discoveries of modern times.
We speak literally when we say, that we doubt if there is a
single publication relating to this subject, either in the ancient
or the modern languages, which he had not diligently perused;
and his knowledge, minute and accurate on every point, and,
once acquired, never forgotten, overflowed in his conversation
and in his writings. The date of any great discovery was
familiar to him; he could give anecdotes or biographical
sketches of all the great promoters of science in every age;
and the prodigality of his information was not more surprising
than the ease with which he preserved its disposition and ar-
rangement, under certain great leading principles, which were
the landmarks of his mind, by which the store of facts which
he had been treasuring up for years was reduced into order,
and each distributed into its proper place in the great system
of which it formed a part. For the truth of this remark we
may refer to the 'History of the Barometer' in the Edinburgh
Review, and to his papers on meteorology and other subjects
in the Encyclopedia Britannica, to his continuation of Play
fair's Introductory Discourses prefixed to that work, as well
as to many of his other productions, which display the great
extent of his researches. On other subjects also, not con-
nected with his peculiar studies, his information was minute
and extensive. He was deeply read in Scottish history and
antiquities; and on all modern questions of-politics or political
economy he had his own original ideas, which he was always
ready to express and expound in a fair and temperate strain."