POT 
turned in a lathe and made into a -variety 
of vessels fit for culinary and other pur- 
posesv 
POTATOE, in Botany, the English name 
for a species of the tuberose-rooted Sola- 
iium. See Solanum. 
POTENT, or Potence, in heraldry, a 
term for a kind of a cross, whose ends all 
terminate like the head of a crutch. It is 
otherwise called the Jerusalem cross. 
POTENTILLA, in botany, dnquefoil, 
a genus of the Icosandria Polygynia class 
and order. Natural order of Senticosse. 
Rosaceae, Jussieu. Essential character : 
calyx ten-cleft ; petals five ; seeds roundish, 
naked, fastened to a small juiceless recep- 
tacle. There are thirty-two species, chiefly 
natives of the South of Europe. 
POTERIUM, in botany, burnet, a genus 
of the Monoecia Polyandria class and order. 
Natural order of Miscellaneae. Rosace®, 
Jussieu. Essential character : male, calyx 
four-leaved ; corolla four-parted ; stamina 
thirty to forty ; female, calyx four-leaved ; 
corolla wheel-shaped,, five-parted ; pistils 
two ; berry formed of the hardened tube 
of the corolla. There are five species. 
POTHOS, in botany, a genus of the Te- 
trandia Monogynia class and order. Natu- 
ral order of Piperit®. Aroide®, Jussieu. 
Essential character : spathe ; spadix sim- 
ple, covered ; calyx none ; petals four ; 
stamina four; berries two-seeded. There 
are thirteen species. 
POTTERY, the manufacture of earthen 
ware, or the art of making earthen vessels. 
The inferior kinds of porcelain, or pottery, 
are prepared by the same process as that 
which has been described under the word 
Porcelain ; less pure, but more fusible 
materials being employed, and of course a 
less degree of heat being applied. 
The better kinds of English stone-ware 
are composed of pipe-clay, amd pounded 
flints. The yellow stone-ware is made of 
the same materials, in other proportions. 
The first is glazed by throwing sea-salt into 
the furnace in which it is baked, when the 
heat is strong ; the salt is converted into 
vapour, and this, being applied to the sur- 
face of the stone-ware, vitrifies it, and 
forms an excellent glazing. The yellow 
stone ware is glazed by dipping, the baked 
ware in water, in which is suspended a 
mixture of pounded flint, glass, and oxide 
of lead. In the glazing of some kinds of 
stone-w'are, oxide, of tin enters into the 
composition with the oxide of lead, and 
gives a whiter glaze. All the coarser kinds 
POT 
of pottery are glazed with oxide of lead ; , 
this promoting so much the fusion and vitri- 
fication, that the low heat at which they 
are baked is sutficieut. 
The w'heel and lathe are the chief, and 
almost the only, instruments used in pot- 
tery : the first for large works, and the last 
for small. The potter’s-wheel consists prin- 
cipally in the nut, whioji is a beam or axis, 
whose foot or pivot plays perpendicularly 
on a free-stone sole or bottom. From the 
four corners of this beam, which docs not 
exceed two feet in height, arise four iron- 
bars, called the spokes of the wheel ; which, 
forming diagonal lines with the beam, de- 
scend, and are fastened at bottom to the 
edges of a strong wooden circle, four feet 
in diameter, perfectly like the felloes of a 
coach-wheel, except that it has neither axis 
nor radii, and is only Joined to the beam, 
which serves it as an axis by the iron-bars. 
The top of the nut is flat, of a circular 
figure, and a foot in diameter: and on this 
is laid the clay which is to be. turned and 
fashioned. The wheel, thus disposed, is en- 
compassed with four sides of four different 
pieces of wood fastened on a wooden 
frame ; the hind-piece, which is that on 
which the workman sits, is made a little in- 
clining towards the wheel ; on the fore- 
piece are placed the prepared earth ; on 
the side-pieces he rests his feet, and these 
are made inclining, to give him more or 
less room. Having prepared the earth, the 
potter lays a round piece of it on the circu- 
lar head of the nut, and, sitting down, turns 
the wheel with his feet till it has got the 
proper velocity ; then, wetting his hands 
with water, he presses his fist or his fingers- 
ends into the middle of the lump, and thus 
forms the cavity of the vessel, continuing to 
widen it from the middle ; and thus turning 
the inside into form with one hand, while 
he proportions the outside with the other, 
the wheel constantly turning all the while, 
and he wetting his hands from time to time. 
When the vessel is too thick, he uses a flat 
piece of iron, somewhat sharp on the edge, 
to pare off what is redundant ; and when it 
is finished, it is taken oif from the circular 
head, by a wire passed underneath the 
vessel. 
The potter’s lathe is also a kind of wheel, 
but more simple and slight than the for- 
mer ; its three chief members are an iron- 
beam or axis three feet and a half high, 
and two feet and a half diameter, placed 
horizontally at the top of the beam, and 
serving to form the vessel upon : and an- 
