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Levelling.

but an exact profile of the mountain is more difficult, a brass wire across a small square hole in the centre, Levelling
as requiring many operations; though some of these which serves to point out the height correctly, by co-
might be obtained by measuring from the level line inciding with the horizontal wire of the telescope of Levite.
without moving the instrument.

the level.
The last example given by our author is likewise LEVEN, a river of Lenox or Dunbartonshire of
from M. le Febure, and includes a length of near five Scotland. See LENOX.
German miles ( 25 of ours) in a straight line, and 9 or LEVER, in Mechanics, is a bar of iron or wood,
10 (45 or 50 English) including the turnings and one part of which being supported by a prop, all other
windings. In this the declivity of the river Haynox parts turn upon that prop as their centre of motion.
was measured from Lignebruk to Villebourg. The This instrument is of two kinds. First, the common
first operation was to drive stakes at several parts of sort, where the weight we desire to raise rests at one
the river even with the water's edge; the first of which end of it, our strength is applied at the other end, and
a little above the mills of Lignebruk showed the upper the prop is between both. When we stir up the fire
water-mark, and another showed the lower water-mark with a poker, we make use of this lever ; the poker is
at the same mills. Two stakes above and below the the lever, it rests upon one of the bars of the grate as
mills of Maxurance, somewhat more than half way be- a prop, the incumbent fire is the weight to be over-
tween Lignebruk and Villebourg, pointed ont the dif. come, and the other end held in the band is the strength
ference between high and low water there, and formed or power. In this, as in all the rest, we have only to
likewise the third and fourth limits of the operation; increase the distance between the strength and prop
while the stakes above and below the mills of Ville. to give the man that works the instrument greater
bourg pointed out the difference between high and low power.
water, and likewise formed the last limits of the opera- The lever of the second kind has the prop at one
tion.

end, the strength is applied to the other, and the weight
These marks were all made at the edge of the wa. to be raised rests between them. Thus in raising ihe
ter, exactly even with its surface, and all made at the water-plug in the streets, the workman puts his iron
different parts of the river nearly at the same instant lever through the hole of the plug till he reaches the
of time." The principal limits of the levelling (say3 ground on the other side, and, making that his prop,

.
Mr Adams) being now determined and fixed, it only lifts the plug with his strength at the other end of the
remains to find the level between the limits, according lever. In this lever also, the greater the distance of
to the methods already pointed out, using every ad- the prop from the strength, the greater is the work-
vantage that may contribute to the success of the work, man's power.
and at the same time avoiding all obstacles and diffi. These instruments, as we see, assist the strength ; but
culties that may retard or injure the operations. The sometimes a workman is obliged to act at a disadvan-
first rule is always to take the shortest possible way tage, in raising either a piece of timber or a ladder
from one limit to another, though this rule ought not to upon one end. We cannot, with grammatical proprie-
be followed if there are considerable obstacles in the ty, call this a lever, since such a piece of timber in fact
way, as hills, woods, marshy ground, or if, by going in no way contributes to raise the weight. In this case,
aside, any advantage can be obtained.” In the pre- the man who is the strength or power, is in the middle,
sent case it was found necessary to deviate very consi- the part of the beam already raised is the weight, the
derably from the general rule, in order to take in se part yet at the ground is the prop on which the beam
veral ponds, the surfaces of which might all be taken turns or rests. Here the man's strength will be dimi-
for a perfect level; and thus levels were frequently nished in proportion to the weight it sustains. The
taken across the country for a considerable way. The weight will be greater the farther it is from the prop,
difference of height between the mills of Lignebruk therefore the man will bear the greater weight, the
and Villebourg was at last found to be about 19 feet, nearer be is to the prop. See MECHANICS.
indicating a descent of not quite a foot in a mile. LEVERET, among sportsmen, denotes a bare in

LEVELLING-Staves, instruments used in levelling, the first year of ber age.
serving to carry the marks to be observed, and at the LEVIGATION, in Pharmacy and Chemistry, the
same time to measure the heights of those marks from reducing hard and ponderous bodies to an impalpa-
the ground. They usually consist of two mahogany ble powder, by grinding them on a porphyry, or in a
staves ten feet long, in two parts, that slide upon one mill.
another to about sit feet, for the more portable car- LEVITE, in a general sense, means all the descend-
riage. They are divided into 1000 equal parts, and ants of Levi, among whom were the Jewish priests
numbered at every tenth division by 10, 20, 30, &c. themselves, who, being descended from Aaron, were
to 1000 ; and on one side the feet and inches are also likewise of the race of Levi. In a more particular
sometimes marked.

sense, Levite is used for an order of officers in that
A vane A slides up and down upon each set of these church, who were employed in performing the manual
staves, which by brass springs will stand at any part. service of the temple. They were obedient to the
These vanes are about 10 inches long and 4 inches priests in their ministration, and brought them wood,
broad; the breadth is first divided into three equal water, and other necessaries for the sacrifice.—They
parts, the two extremes painted white, the middle sung and played upon instruments in the temple and
space divided again into three equal parts, which are in other places. They applied themselves to the study
less; the middle one of them is also painted white, and of the law, and were the ordinary judges of the coude
the two other parts black; and thus they are suited try, but always subordinate to the priests. Their sub-
to all the common distances, These vanes bave each sistence was the tithes of corn, fruit, and cattle,
3

throughout

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