454 
FLU 
PLU 
P L U 
look-out, for fear of being run down by ships, 
and to observe the weather ; for storms often 
rise so suddenly, that it is with extreme*diffi- 
culty they can escape to shore, leaving their 
lines behmd. The coble is twenty feet six 
inches long, and five feet in extreme breadth : 
it is about one ton burthen, rowed with three 
pair ot oars, and admirably constructed for 
the purposes of encountering a mountainous 
sea. They hoist sail when the wind suits.” 
PLICA POLONIGA. See Medicine. 
PLINIA, a genus of plants of the poly- 
andria monogynia class. The empalement 
is divided into rive segments ; the flower con- 
sists of five petals ; the stamina are 'numerous 
filaments, slender, and as long as the flower; 
the anthera are small, and so is the germen 
ot the pistil ; the sty le is subulated, and of 
the length of the stamina; the stigma is 
simple ; the fruit is a large globose berry, of 
a striated or suicated surface, containing only 
one cell, in which is a very large, smooth, 
and globose seed. There are two species, 
trees of America. 
PLINTH. See Architecture. 
PLOCAMA, a genus of the monogynia 
order, in the pentandria class of plants. The 
calvx is quinquedentate ; the fruit a berry 
and trilocular, with solitary seeds. Of this 
there is only one species, viz. the penduia, a 
native of the Canaries. 
PLOTTING, among surveyors, is the art 
of laying down on paper, See. the several 
angles and lines of a tract of ground surveyed 
by a theodolite. Sec. and a chain. See Sur- 
veying. 
P LOTUS, or Darter, a genus of birds 
of the order anseres. 'Idle generic character 
is, bill straight, pointed, toothed ; nostrils a 
slit near the base ; face and chin naked ; legs 
short, all the toes connected. Of this genus 
there are three species. 
P. anhinga: head smooth; belly white: 
inhabits Brasil ; two feet ten inches long ; 
builds on trees, and is hardly ever seen on 
the ground : when at rest, sits with the neck 
drawn in between the shoulders; flesh oily 
and rancid. 
P. melanogaster, inhabits Ceylon and Java; 
about three feet long: and the P. surinamen- 
sis, has its head crested, and belly white ; it 
inhabits Surinam ; is 13 inches long; is do- 
mesticated, and feeds on fish, insects, espe- 
cially flies, which it catches with great dex- 
terity, and is very active. 
PLOVER. See Charadrius. . 
PLOUGH. See Husbandry. 
PLOUGHING. See Husbandry. 
PLUKENETIA, a genus of the monoecia 
monadelphia class and order. The male and 
female flowers are produced separately' on 
the same plant ; the corolla is composed Of 
four oval and patent petals, and the stamina 
form a short pyramidal body : the fruit is a 
depressed quadrangular capsule, containing a 
single roundish and compressed seed. There 
is one species. 
PLUM-TREE. SeePRUNus, 
PLUMBAGO, lead-wort, a genus of the 
monogynia order, in the pentandria class of 
plants. The corolla is funnel-form ; stamina 
inserted in scales, inclosing the base of the 
corolla ; stigma flve-cleft ; seed one. There 
are seven species, the most remarkable of 
which are the Europaa and Zeylonica. The 
first grows naturally iu the southern parts of 
Europe, and has a perennial root striking 
deep in the ground. There are many slen- 
der enamelled stalks, about three feet high, 
terminated by tufts of sirkill funnel-shaped 
flowers, of a blue , or white colour. The se- 
cond grows naturally in both the Indies. The 
upper part of the stalk and empalement are 
covered with a glutinous juice, which catches 
the small flies that light upon it. The for- 
mer species is propagated bv parting the 
roots, and by seeds; but the latter is too 
tender to thrive in the open air in this coun- 
try. 
Plumbago, carburet of iron. This mine- 
ral is found in various parts of Europe and 
America. It occurs in kidney-form lumps of 
various sizes. Its colour is dark iron-grey, 
or brownish-black ; when cut, blueish-grey. 
Opaque and slaty; texture fine-grained; 
brittle; specific gravity from 1.98 to 2.09; 
feels somewhat greasy; stains the fingers, and 
marks strongly. The use of this mineral, 
when manufactured into pencils, is known to 
every person. It consists of 
90 of 'car bon 
1 0 of iron 
100 . 
PLUMBERY, the art of casting and work- 
ing lead, and using it in buildings. 
As this metal melts very easily, it is easy to 
cast it into figures of any kind, by running 
it into moulds of brass, clay, plaister, &c. But 
the chief article in plumbery is sheets and 
pipes of lead ; and as these make the basis of 
the plumber’s work, we shall here give the 
process of making them. 
In casting sheet-lead, a table or mould is 
made use of, which consists of large pieces of 
wood well jointed, and bound with bars of 
iron at the ends ; on the sides of which runs a 
frame consisting of a ledge or border of 
wood, two or three inches thick, and two or 
three inches high from the mould, called the 
sharps : the ordinary width of the mould, 
within these sharps, is from three to four feet, 
and its length is 16, 17, or 18 feet. This 
should be something longer than the sheets 
are intended to be, in order that the end 
where the metal runs off from tlve mould may 
be cut off; because it is commonly thin, or 
uneven, or ragged at the end. It must stand 
very even or level in breadth, and something 
falling from the end in which the metal is 
poured in, viz. about an inch or an inch and 
a half, in the length of 16 or 17 inches. At 
the upper end of the mould stands the pan, 
which is a concave triangular prism, com- 
posed of two planks nailed together at right 
angles, and two triangular pieces fitted in be- 
tween them at the ends. The length of this 
pan is the whole breadth of the mould in 
which the sheets are cast ; it stands with its 
bottom, which is a sharp edge, on a form at 
the end of the mould, leaning with one side 
against it ; and on the opposite side is a han- 
dle to lift it vip by, to pour out the melted 
lead ; and on that side of the pan next the 
mould, are two iron hooks to take hold of 
the mould, and prevent the pan from slip- 
ping, while the melted lead is pouring out of 
it into the mould. This pan is lined on the 
inside with moistened sand, to prevent it from 
being fired by the hot metal. The mould is 
also spread over, about two-thirds of an inch 
thick, with sand sifted and moistened, which 
is rendered perfectly level by moving over it 
a piece of wood called a strike, by trampling 
upon it with the feet, and smoothing it over 
with a smoothing-plane ; which is a thick plate 
ot polished brass, about nine inches square, 
turned up on all the four -edges, and with a 
handle fitted on to the upper or concave 
side. The sand being thus smoothed, it is lit 
for casting sheets of lead ; but if they would 
cast a cistern, they measure out the sir-' of 
the four sides, and having taken the di. u- 
sions ot the front or fore-part, make mould- 
ings by pressing long slips of wood, which 
contain the same mouldings into the level 
sand ; and form the figures of birds, beasts, 
&c. by pressing in the same manner leaden 
figures upon it, and then taking them off, 
and at the same time smoothing the surface 
where any of the sand is raised up by mak- 
ing these impressions upon it. The rest' of 
the operation is the same in casting either 
cisterns or plain sheets of lead. But before 
we proceed to mention the mamfer in which 
that is performed, it will be necessary to give 
a more particular description of tlie strike. 
I he strike theu is a piece of board about five 
inches broad, and something longer than the 
breath of the mould on the inside ; and at 
each end is cut a notch, about two inches 
deep, so that when it is used, it rides upon the 
sharps with those notches. Before they be- 
gin to cast, the strike is made ready by tack- 
ing two pieces of an old hat on the notches, 
or by slipping a case of leather over each end, 
in order to raise the under side about one- 
eighth ot an inch, or something more, above 
the sand, according as they would have the 
sheet to be in thickness; then they tallow the 
under edge ot the strike, and lay it across the 
mould. 'Die lead being melted, it is laded 
into the pan, in which, when there is a suffi- 
cient quantity for the present purpose, the 
scum of the metal is swept off with a piece of 
board to the edge of the pan, letting it settle 
on the sand, which is by this means prevent- 
ed from falling into the mould at the pouring 
out of the metal. \V hen the lead is cool 
enough, which is known by its beginning to 
stand with a shell or wall on the sand round 
the pan, two men take the pan by the han- 
dle, or else one of them lifts it up by a bar 
and chain fixed to a beam in the ceiling, and 
pour it into the mould, while another man 
stands ready with the strike, and, as soon as 
they’have done pouring in the metal, puts on 
the mould, sweeps the lead forward, and 
draws the overplus into a trough prepared 
to receive it. The sheets being thus cast, 
nothing remains but to planish the edges, in 
order to render them smooth and straight * 
but if it is a cistern, it is bent into four sides, 
so that the two ends may join the hack, 
where they are soldered together, after which 
the bottom is soldered up. 
The method of casting pipes without sol- 
dering. To make these pipes, they have a 
kind of little mill, with arms or levers to turn 
it with. The moulds are of brass, and con- 
sist of two pieces, which open and shut by 
means of hooks and hinges, their inward ca- 
liber or diameter being according to the size 
of the pipe to be made, and their length is 
usually two feet and a half. In the middle 
is placed a core, or round piece of brass or 
iron, somewhat longer than the mould, and 
of the thickness of the inward diameter of the 
pipe. This core is passed through two cop- 
per-rundles, one at each eud of the mould. 
