LEV 
gutter, made of two pieces of planks, like 
those under the eaves of houses, may be 
made to answer the purpose ; by support- 
ing either end, until the water may come to 
a level in every part. 
Where works of moderate extent are 
' carried on, > and where the perfect level of 
each stratum of materials is not an object 
of importance the common bricklayer’s 
level, made in the form of an inverted T, 
thus X, having a plumb suspended from the 
top, and received in an opening at the junc- 
tion of the perpendicular with ttie hori- 
zontal piece, will answer well enough. The 
principle on which this acts, is, that as all 
weights have a tendency to gravitate to- 
wards the centre of the earth, so as the 
plumb line, is a true perpendicular, any 
line, cutting that at right angles must be a 
horizontal line at the point of intersec- 
tion. 
Level, artillery-fool, is in form of a 
square, having its two legs or branches of 
an equal length, at a juncture whereof is a 
little hole, whence hangs a thread and 
plummet, playing on a perpendicular line 
in the middle of a quadrant. It is divid- 
ed into twice forty-live degrees from the 
middle. 
This instrument may be used on other 
occasions, by placing the ends of its two 
branches on a plane ; for when the thread 
plays perpendicularly over the middle divi- 
sion of the quadrant, that plane is assuredly 
level. To use it in gunnery, place the two 
ends on the piece of artillery, which you 
may raise to any proposed height, by means 
of the plummet, whose thread \vill give the 
degree above the level. 
Level, carpenter’s and parAour’s, consists 
of a long ruler, in tlie middle whei'eof is 
fitted, at right angles, another somewhat 
bigger, at the top of which is fastened a 
line, which, when it hangs over a fiducial 
line at right angles with the base, shows 
that the said base is horizontal. Some- 
times this level is all of one board. 
Level, gunner’s, for levelling cannons 
and mortars, consists of a triangular brass 
plate, about four inches high, at the bot- 
tom of which is a portion of a circle, divid- 
ed into forty-five degrees, which number is 
sufiicient for the highest elevation of can- 
nons and mortars, and for giving shot the 
greatest range ; on the centre of this seg- 
ment of a circle is screwed a piece of brass, 
by means of which it may be fixed or 
screwed at pleasure ; the end of this piece 
of brass is made so as to serve for a plura- 
LEV 
met and index, in order to show the dif- 
ferent degrees of elevation of pieces of 
artillery. This instrument has also a brass 
foot, to set upon cannons or mortars, so as 
when those pieces are horizontal, the in- 
strument will be perpendicular. The foot 
of this instrument is to be placed on the 
piece to be elevated, in sucb a manner as 
that the point of the plummet may fall on 
the proper degree : this is what they call 
levelling the piece. 
Level, mason’s, is composed of three 
rules, so joined as to' form an isosceles- tri- 
angle, somewhat like a Roman A, at the 
vertex whereof is fastened a thread, from 
which hangs a plummet, that passes over a 
fiducial line, marked in the middle of the 
base, when the thing, to which the level is 
applied, is horizontal ; but declines from 
the mark, when the thing is lower on one 
side than on the other. 
Level, plumb or pendulum, that which 
Shews the horizontal line by means of 
another line perpendicular to that describ- 
ed by a plummet or pendulum. This in- 
strument consists of two legs or branches, 
joined together at right angles, whereof 
that w'hich carries the thread and plummet 
is about a foot and a half long; the thread 
is hung towards the top of the branch. 
The middle of the branch where the 
thread passes is hollow, so that it may 
hang free every where : but towards the 
bottom, where there is a little blade of 
silver, whereon is drawn a line perpendi- 
cular to the telescope, the said cavity is 
covered by two pieces of brass, making as 
it were a kind of case, lest the wind should 
agitate the thread ; for which reason the 
silver blade is covered with a glass to the 
end, that it may be seen when the thread 
and plummet play upon the perpendicular, 
The telescope is fastened to the other 
branch of the instrument, and is about two 
feet long; having an hair placed horizon- 
tally across the focus of the object-glass, 
which determines the point of the level. 
The telescope must be fitted at right angles 
to the perpendicular. It has a ball and 
socket, by which it is fastened to the foot. 
LEVELLING. See Level. 
Levelling staves, instruments used in 
levelling, serving to carry the marks to be 
observed, and at the same time to mea- 
sure the heights of those marks from the 
ground. They usually consist each of two 
long wooden rulers, made to slide over one 
another, and divide into feet, inches, &c. 
LEVER, in mechanics, an inflexible right 
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