After his return to France lie taught at Toulouse,
Besancon, and N'aney. He was appointed to the
chair of l^atin and Greek philosophy at the Col-
lege of France in lS5(i, and liecame a iiieinl)er of
the Institute in 1805, and vice-president of the
Aeadi'niie des Sciences Alorales et I'olitiques in
187.'!. In philosophy he was a pupil of I'ousin.
His works include: La plii/si(iiii' d'Aiislntc et
la science contcmporaine (1800) : La science dii
beau, ses principes, scs applicitiions, son histoirc
(1872) ; Etudes de pitilosophie grccqne et latine
(1864); Le spirit iuilism<: dans I'art (1804);
La science de I'incisible (1865) ; and I^es har-
monies provident ielles (1872; 4th ed. 1885).
LEVER (OF. lercor, Icveiir, Ft. leveur, lever,
from Lat. levator, lifter, from levarc. to raise).
A form of machine much useil in simple physical
instruments. It consists essentially of a rigid
body pivoted at one point. If tlie lindy is acted
on by two forces ( F, and F,) in ditrerent direc-
tions, which hold it in equilibrium, the formula
for the mechanical advantage can l)e deduced at
once; the general principle being that since there
I
•<-
/
is equilibrium the moment of one force around
the pivot at P, i. e. F,/,, must equal the moment
of the second force around the same axis, i.e.
FjL. The lixeii point is called the "fulcrum.' and
i, and /^ the 'lever-arms.' Thus to balance a
force F, a force l'"2 is necessary, where F,/, = F,L,
The 'mechanical advanUige' is therefore, /,//,.
Another mode of deducing the same formula is
to consider the system displaced slightly when in
equilibrium under the forces F, and F.. The
point of application of F, will move a distance
x; that of F,, a distance x,. By the principle
of energy F,a;,=Fja;2; but by geometry, if the
displacement is small, -l-=---?,and hence FJ,=:
FjJj, as l)efore.
In some levers the fulcrum lies between the
two balancing forces, e.g. pump-handle, crow-
bar, scissors. In other cases it lies beyond the
forces, e.g. sugar-tongs, nut-cracker, claw-ham-
mer, a wheelbarrow. See Mectia.mcs.
LEVER, Charles .Tames (1806-72). An
Irish novelist, born in Dublin, August .31, 1806.
He graduated B. A. from Trinity College, Dublin,
in 1827, and then studied medicine at Oiittingen,
Germany. A visit to Canada in 1820 he subse-
quently turned to good use in Arthur O'Lean/
(1S44) and Con Oregon (1840). Returning to
Dublin, he took his medical degree at Trinity
(1831), and received several appointments from
the Board of Health. In the Dublin I'nirersitti
Magazine for February, 1837, appeared the first
installment of Barrii Lorrequer. This was fol-
lowed by Charles O'ilalley, Jack Hinton. the
Guardsman, Tom Burke of Ours. The Martins of
Cro' Martin, and Roland Cashel. These novels,
pervaded with a spirit of farcical humor, were
innnensely popular. By 1850 the vein had, how-
ever, been a little too well worked. Lever dis-
])layed a quieter humor in The Oodd Family
Abroad (1853-54), depicting English life on the
Continent. His later work is less interesting.
Ijcver lived much on the Continent and there
gathered material for his novels. In 1840 he
was physician to the British Legation at Brussels.
In 1857 he was appointed Consul at Spezia and
ten years later at Trieste, where he died .lune 1,
1872. His ^'orks were published by Koutlcdge
(33 vols., London, 1876-78; since reprinted), ajid
in the Barrington Edition (32 vols., Boston,
1002). Consult his Life, by Fitzpatrick (London,
1870).
LEVERET (OF. levrri, diminutive of Icvre.
Fr. lit'rre. It. Icpre, hare, from Lat. li-pus. hare).
The young of the hare during the first year of its
age. See Hare.
LEV'ERETT, -loiix (1610-79). An American
colonial otlicial. He came to Boston with his
father in 1033 from Boston Parish, England, but
went back to serve in the Parliamentary Army
in 1644. He was a captain inider Cromwell, who
became his friend. On his return to Boston he
was a member of the General Court (1651-52),
and was sent to bring Maine under the jurisdic-
tion of Massachusetts. He also took part in tlie
capture of settlements along the Saint LawreiU'e.
In 1606 he went to England to represent the
Colony, and remained six years. On his return
he was made Speaker of the General Court and
major-general of the militia. For six years he w.qs
in the Governor's Council, and was then made
Deputy Governor. When Bcllingham died in
1672 he filled out his term. He was regularly
elected Governor in 1673, and died in office. Con-
sult the Report of the New England Genealogical
Society for 1881.
LEVERRIER, Ic-var'yu', I^rbaix .Jean .Jo-
seph (1811-77). A French astronomer, born at
Saint-Lo. He was admitted to the Ecole Polytech-
nique in 1831, and was subsequently employe<l for
some time as an engineer in connection with the
Government tobacco monopoly. His Tables de
Mercure and several memoirs on 'the secular
inequalities' opened to him the door of the
Academy in 1846. At the instance of Arago
he applied himself to the examination of the
disturbances in the motions of the planets, from
which the existence of an undiscovered planet
could be inferred; and, as the result of his
laborious calculations, directed the attention of
astronomers to the point in the heavens where, a
few days afterwards, the planet Neptune was
actually discovered. The elements of the orbit
of the planet had also been calculated by the
English astronomer Adams in 1845, but no search
was made for the planet. For this Leverrier was
rewarded with the grand cross of the Legion of
Honor, a professorship of astronomy in the
Faculty of Sciences at Paris, and various minor
honors. In 1854 Leverrier was appointed to the
directorship of the Observatory of Paris, an office
which, .save during an interval of three years
(1870-73), he held till his death. See Adams,
.John CotTrii ; Xeptune.
LEVERWOOD. A synonym for ironwood.
See Hornbeam.
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LEVEQUE.
170
LEVERWOOD.