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orders, after a series of years, the cause was 
discovered to be their having used the water 
of a leaden pump, which had been gradually- 
dissolved, and thus rendered the water poi- 
sonous. For the treatment ot colic and palsy 
see Medicine. Calomel administered in 
small doses, till ptyalism is produced, is the 
most effectual way' of restoring sensibility to 
the nerves, when lost from this cause. 
We cannot sufficiently express our abhor- 
rence of the cruel, the detestable experiments 
made by certain practitioners upon poor 
dumb creatures, to ascertain the effects of 
poisons; experiments made in general to 
gratify an idle curiosity, but which no motive 
can justify. We feel an honest pride in re- 
flecting that few of these experimentalists 
have been Englishmen ; and as our work is 
addressed to that generous and humane na- 
tion, we have not outraged their feelings by 
the shocking detail. 
POLE, in spherics, a point equally distant 
from every part ot the circumference of a 
great circle of the sphere, as the centre is in 
a plane figure; or it is a point 90° distant 
from the plane of a circle, and in a line, 
called the axis,- passing perpendicularly 
through the centre. The zenith and nadir 
are the poles of the horizon ; and the poles 
of the equator are the same with those of the 
sphere. See Globe. 
Poles. See Ecliptic. 
Poles. See Magnetism. 
Pole or vertex of a glass, in optics, is 
the thickest part of a convex, or the thinnest 
of a concave glass. If the glass is truly 
ground, the pole will be exactly in the mid- 
dle of its surface. 
Pole, Perch, or Rod, in surveying, is a 
measure containing sixteen feet and a half. 
Pole or polar star, is a star of the se- 
cond magnitude, the last in the tail ot ursa 
minor. Its longitude Mr. Flamsteed makes 
2 4° 14' 41" ; its latitude 66° 4' 1 1". 
Pole-Cat. See Viverra. 
POLEMONIUM, Greek valerian, or 
Jacob's ladder ; a genus of the monogynia 
order, in the pentandria class of plants ; and 
in the natural method ranking under the 
29th order, campanaceae. The corolla is 
quinquepartite ; the stamina inserted into 
scales, which close the bottom of the corolla; 
the stigma is trifid ; the capsule bilocular su- 
perior. There are five species, of which the 
most remarkable is the caeruleum, with an 
empalement longer than the flower. It grows 
naturally in some places ot England: its 
beauty, however, has obtained it a place in 
the gardens. There are three varieties; one 
with a white, another with a blue, and ano- 
ther with a variegated flower; also a kind 
with variegated leaves. They are easily pro- 
pagated by seeds ; but that kind with varie- 
gated leaves is preserved by parting its roots, 
because the plants raised from seeds would be 
apt to degenerate and become plain. 
POLEMOSCOPE; in optics, a kind of 
reflecting perspective-glass invented by Iie- 
velius, who commends it as useful in sieges, 
&c. for discovering what the enemy is do- 
ing, while the spectator lies hid behind an 
obstacle. Its description is this:. The inter- 
val between the object-glass and the specu- 
lum, is enlarged by a tube, ot a length 
sufficient to project the speculum beyond 
Vox.. II. 
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the obstacle that covers the observer. And 
for a further convenience of looking for- 
ward, as it were, he proposes to place 
another plane speculum at the other end 
of the tube, to reflect the rays through a 
hole in its side, in a direction parallel 
to the incident rays,; and to place the 
concave eye-glass in this hole. By this 
means, the object will still appear upright, 
and magnified just as much as if the two spe- 
culums were removed, and the same eye-glass 
was placed in the axis of the tube. 
POLIANTHES, the tuberose : a genus of 
the monogynia .order, in the hexandria class ‘ 
of plants ; and in the natural method ranking 
under tiie 10th order, coronarise. The co- 
rolla is funnel-shaped, incurvated, and equal ; 
the filaments are inserted into the throat of 
the corolla, in the bottom of which the ger- 
men is situated. There is but one species, 
consisting of some varieties ; all of which, be- 
ing exotics of tender quality, require aid of 
artificial heat, under shelter of frames and 
glasses, &c. to bring them to flower in perfec- 
tion in this country. The varieties are the 
; common tuberose, with single flowers ; 
double-llowered, dwarf-stalked, variegated- 
leaved. They all flower here in June, July, 
and August: the flowers are funnel or bell- 
shaped ; on the upper part of the stem is a 
long spike, consisting of from 10 to 20 or 
more separate in alternate arrangements, the 
lower flowers opening first, which are suc- 
ceeded by those above, in regular order, mak- 
ing in the whole a most beautiful appearance, 
highly enriched with a most fragrant odour. 
The common single-flowered tuberose is the 
sort the most commonly cultivated, as it ge- 
nerally blows the most freely, and possesses 
the finest fragrance. The donble-llowered 
kind also highly merits culture, as when it 
blows fair it makes a singularly fine appear- 
ance. The dwarf and the variegated kinds 
are inferior to the other two, but may be cul- 
tivated for variety. All the varieties being 
exotics from warm countries, although they 
are madefto flower in great perfection in our 
gardens by the assistance of hotbeds, they 
will not prosper in the open ground, and do 
not increase freely in England ; so that a sup- 
ply of the roots is imported hither annually 
from Genoa, and other parts of Italy. The 
principal season for planting them is March 
and April: observing, however, that in order 
to continue a long succession of the bloom, it 
is proper to make two or three different 
plantings, at about a month interval ; one in 
March, another in April, and a third the be- 
ginning of May, whereby the bloom may be 
continued from June until September; ob- 
serving, as above mentioned, they may be 
flowered either by aid of a common dung or 
bark hotbed, or in a hot-house. 
POLICY of ASSURANCE. The deed 
or instrument by which a contract of assur- 
ance is effected." The premium or considera- 
tion paid for the risk or hazard assured 
against, must be inserted in the policy, and 
likewise the day, month, and year, on which 
the policy is executed, and it must be duly 
stamped. Policies for assurance against the 
risks of the sea are distinguished into valued 
and open policies; in the former the goods or 
property assured are valued at prime cost at 
the time of effecting the policy ; in the lat- 
ter, the value is not mentioned, but is left to 
O 
P O L 473 
he afterwards declared, or to he proved in the 
event of a claim. In a valued policy, the 
proper effect of the valuation is, the fixing the 
amount of the prime cost, in the same manner 
as if the parties had admitted it at a trial; but 
for e very other purpose, it must be taken that 
the value was fixed in such a manner as that 
the insured meant to have an indemnity and 
no more. The practice of permitting the in- 
sured on a valued policy to recover the whole 
sum insured upon a total loss, though his in- 
terest is less than that sum, is against the 
statute. A valued policy on profits expected 
upon a voyage is not within the act, the ob- 
ject of an insurance being an indemnity. When 
a policy is once executed, it cannot be altered 
by either party, as this would open a door to an 
infinite variety of frauds, and introduce uncer- 
tainty into a species of contract, of which cer- 
tainty and precision are the most essential re- 
quisites. If, however, a policy is filled up by 
mistake different from the original agreement, 
it may, even after signing, be corrected by 
tiie consent of both parties. An underwriter 
may, however, shift. the insurance, or any part 
of it, from himself to other insurers, by caus- 
ing a re-insurance to be made on the same 
risk, and the new insurers will be responsible 
to him, in case of loss, to the amount of the 
re-insurance ; but the re-insurer is only re- 
sponsible to the original insurer, and not to 
the original insured. The form of the po- 
licies in common use by the underwriters 
of London, for sea-assurances, is nearly the 
same which was adopted two hundred years 
ago ; but Mr. Park remarks that its antiquity 
cannot preserve it from just censure, it being 
very irregular and confused, and frequently 
ambiguous, from making use of the same 
words in different senses. The policies ge- 
nerally used for assurances on lives, or against 
lire, are much more correct and intelligible. 
POLIERSHIEFER, a mineral body found 
chiefly at Mend Montant, near Paris. Co- 
lour grey ; often reddish ; sometimes spotted 
or striped brownish-black, and lemon-yellow. 
Found in strata; texture earthy; fracture 
conchoidal ; structure shistose ; very soft ; 
easily broken ; adheres strongly 'to the 
tongue 5 feel harsh; specific gravity 2.08; 
absorbs water with avidity ; melts to a black- 
ish slag ; constituents, 
60.50 silica 
7.00 alumina 
1.50 magnesia 
1.25 lime 
2.50 oxide of iron 
19.00 water. 
97.75 
POLISHER, or burnisher, among me- 
chanics, an instrument for polishing and burn- 
ishing things proper to take a polish. The 
gilders use an iron polisher to prepare their 
metals before gilding, and the blood-stone to 
give them the bright polish after gilding. 
The polishers among cutlers, are a kind of 
wooden wheels made of walnut-tree, about an 
inch thick, and of a diameter at pleasure, 
which are turned round by the great wheel ; 
upon these they smooth and polish their worlt 
with emery and putty. 
The polishers for glass consist of two pieces 
of wood; the oue flat, covered with old hat; 
