PNE 
screw, on which the hollow ball, b, is screw- 
ed, in order to be filled with condensed air. 
In the inside of this ball is a valve, to hinder 
the air after it is injected from making its 
escape, until it be forced open by a pin, 
against which the hammer of the lock 
strikes ; which then lets out as much air as 
will drive a ball with considerable force to 
a great distance. 
When you condense the air in the ball, 
place your feet on the iron cross, hh, to 
which the piston-rod, d, is fixed ; then lift 
off the barrel, ea, by the handles, ii, until 
the end of the piston is brought between e 
andc; the barrel, a c, will then be filled 
with air through the hole, e. Then thrust 
down the barrel, ac, by tlie handles, ii, 
until the piston, e, join with the neck of the 
iron ball at a; the air being thus condensed 
between e and a will force open the valve 
in the ball, and when the handles are lifted 
up again the valve will close and keep in 
the air, in this manner the ball will pre- 
sently be filled ; after which, unscrew the 
ball off the condenser, and screw it upon 
another male screw, which is connected 
with the barrel, and goes through the stock 
of the gun, as represented (fig. f 2). The 
whole will he better understood by (fig. 13) 
which is a section of the gun. The inside, 
k, is that from which the bullets are shot, 
and, C D S R, is a larger barrel. In the 
stock of the gun, M, which forces the air 
through the valve, E P, into the cavity be- 
tween the two barrels. There is a valve at 
S L, which being opened by the trigger, O, 
permits the air to rush suddenly behind the 
bullet, so as to drive it out with great force. 
If the valve is suddenly opened and closed, 
one charge of condensed air may make 
several discharges of bullets. 
PNEUMORA, in natural history, a ge- 
nus of insects of the order Hemiptera. 
Body ovate, inflated, diaphanous ; head in- 
flected, armed with jaws ; thorax convex, 
carinate beneath ; wing-cases deflected, 
membranaceous; legs formed for running. 
There are only three species, viz. 1. P. im- 
maculata : green-spotted with white ; wing- 
cases immaculate. 2. P. maculata : wing- 
cases, green, with square white spots. And, 
3. P. guttata : wing-cases green, with two 
white spots ; abdomen with three white 
spots on each side. They are all found at 
the Cape of Good Hope. The insects of 
this genus appear to consist of a mere hol- 
low inflated membrane : by rubbing toge- 
ther their serrate, or toothed legs, they 
make a shrill kind of noise morning and 
POE 
evening, and follow a light ; and they are so 
nearly allied to the cricket tribe, that they 
have been enumerated by some naturalists 
under the genus Gryllus. 
POA, in botany, meadow-grass, a genus 
of the Triandria Digynia class and order. 
Natural order of Gramina, or Grasses. Es- 
sential character : calyx two-valved, many- 
flowered ; spikelet ovate ; valves scariose at 
the edge, and sharpish. There are seventy- 
one species. 
POCKET, in the woollen trade, a word 
used to denote a large sort of bag in which 
wool is packed up to be sent from one part 
of the kingdom to another. The pocket 
contains usually twenty-five hundred weight 
of wool. 
PODOPHYLLUM, in botany, a genus 
of the Polyandria Monogynia class and 
order. Natural order of Rhoeadeae. Ramin- 
culaceae, Jussieu. Essential character : ca- 
lyx three-leaved ; corolla nine-petalled ; ber- 
ry one celled, crowned wjith the stigma. 
There are two species, viz. P. peltatum, 
duck’s-foot, or May-apple; andP. diphyllum. 
PODUR'A, in natural history, spring-tail, 
a genus of insects of the order Aptera. Ge- 
neric character : lip bifid ; four feelers, sub- 
clavate ; two eyes, composed of eight 
facets ; antennae filiform ; body scaly ; tail 
forked, bent under the body, and acting as 
a spring, hence its name ; six legs, formed 
for running. There are thirty-one species. 
They feed on leaves of various plants : the 
larva and pupa are six-footed, nimble, and 
resemble the perfect insect. P. aquatica 
is black, and, as its name imports, aquatic ; 
they assemble in troops early in the morn- 
ing, on the banks of pools and fish-ponds. 
P. ambulans is white, with a bifid extended 
tail, and is found principally among moss. 
POETICAL rising and setting of the 
stars. The three kinds of rising and setting, 
viz. the cosmical,5 acronical, and heliacal, 
were made by the ancient poets, referring 
the rising, &c. of the stars to that of the 
sun. 
POETRY. Dr. Blackwall, in his “ Es- 
say on the Life and Writings of Homer,” 
says, on the subject of poetry, that “ it is of 
a nature so delicate, as not to admit of a 
direct definition ; for if ever the je ne scais 
quoi was rightly applied, it is to tlie powers 
of poetry, and the faculty that produces it. 
To go about to describe it would be like, 
attempting to define inspiration, or that 
glow of fancy, or elfusion of soul, which a 
poet feels while in his fit ; a sensation so 
strong, that they express it only by adjur- 
