A74 
P O l 
?01 
POL 
the other long and half-round, fastened on 
the former, whose edge it exceeds on both 
sides by some inches, which serve the work- 
men to take hold of, and to work backwards 
and forwards by. 
The polishers used by spectacle-makers 
are pieces of wood a foot long, seven or eight 
inches broad, and an inch and a half thick, co- 
vered with old beaver-hat, on which they 
polish the shell and horn frames their specta- 
cle-glasses are to be set in. 
POLISHING, in general, the operation of 
giving a gloss or lustre to certain substances, 
as metals, glass, marble, &c. 
The operation of polishing optic glasses, 
after being properly ground, is one of the 
most difficult points of the whole process. 
Before the polishing is begun, it is proper to 
stretch an even well-wrought piece of linen 
over the tool, dusting upon it some very line 
tripolu Then taking the glass in your hand, 
run it round forty or iifty times upon the tool, 
to take off the roughness of the glass about the 
border of it. This cloth is then to be re- 
moved, and the glass to be polished upon the 
naked tool, with a compound powder made 
ot four parts tripoli mixed with one of fine 
blue vitriol ; six or eight grains of which mix- 
ture are sufficient for a glass five inches broad. 
This powder must be wetted with eight or ten 
drops of clear vinegar, in the middle of the 
tool; being first mixed and softened thorough- 
ly with a very line small mullet. Then with 
a nice brush, having spread this mixture 
thinly and equably upon the tool, take some 
very fine tripoli, and strew it thinly and equa- 
bly upon the tool so prepared; after which, 
take the glass to be polished, wiped very 
clean, and apply it on the tool, and move it 
gently twice or thrice in a straight line back- 
wards and forwards ; then take it off, and 
Observe whether the marks of the tripoli, 
Sticking to the glass, are equably spread over 
the whole surface; if not, it is a sign that 
either the tool or glass is too warm, in which 
case you must wait awhile and try again, till 
you find the glass takes the tripoli every 
where alike. 1 hen you may begin to polish 
boldly, there being no danger of spoiling the 
figure of the glass, which in the other case 
would infallibly happen. This is Mr. Huy- 
gens’s method; but it ought to be observed, 
that almost every operator has a peculiar one 
®f his own, and of which some of them make 
a mighty secret. 
Sir Isaac Newton no where expressly de- 
scribes his method of polishing optical glasses ; 
but his method of polishing reflecting metals 
he thus describes in his Optics. He had two 
round copper plates, each six inches in di- 
ameter, the one convex, the other concave, 
ground very true to one another. On the 
convex one he ground the object-metal, or 
concave which was to be polished, till it had 
taken the figure of the convex, and was ready 
sfior a polish. He then pitched over the con- 
vex very thinly, by dropping melted pitch 
upon it, and warming it to keep the pitch 
soft, whilst he ground it with the concave 
copper wetted, to make it spread evenlv all 
©ver the convex, till it was no thicker than a 
groat-piece ; and after the convex was cold 
he ground it again, to give it as true a figure 
as poss.ble. He then ground it with very 
jfeue putty, till it made no noise; and then 
upon the pitch he ground the object-metal 
with a brisk motion for two or three minutes ; 
when laying fresh putty upon the pitch, he 
ground it again till it had done making a 
noise, and afterwards ground the object- 
metal upon the pitch as before: and this 
operation he repeated till the metal was per- 
fectly polished. 
POLITICAL ARITHMETIC, calcula- 
tions relating to the wealth of nations. Poli- 
tical arithmetic does not determine in what 
national wealth truly consists, but estimates 
the value of whatever passes under this name, 
and distinguishes the proportions in which 
the component articles may be applied to 
purposes conducive to the safety or prospe- 
rity of the community. It must be admitted 
that in the application of arithmetic to the sub- 
jects of political economy, it unavoidably 
loses much of its precision, from the fluctu- 
ating nature of most descriptions of property, 
both with respect to distribution and value, 
the state of which it is one of its chief objects 
to estimate; it however retains a sufficient 
degree of certainty to become an interesting 
subject to every individual who wishes to ac- 
quire a just idea of the strength and resources 
either of the community to which he belongs, 
or of other nations. 
If the particulars which it is necessary to 
assume as facts could be obtained correct, the 
conclusions drawn from them would be nearly 
as determinate and invariable as in any other 
branch of arithmetic ; but if the former are 
not strictly true, the latter will be but ap- 
proximations, however near they may come 
to the truth. Such approximations, however, 
may be sufficient for most useful purposes; 
though it must be confessed that a greater 
degree of certainty, which would render our 
knowledge on this subject more valuable, is 
highly desirable ; at the same time it is diffi- 
cult to attain, as it does not depend so much 
on the labours or -investigations of Individu- 
als, as on the measures adopted by the go- 
vernments of different countries, who alone 
possess the means of ascertaining with great- 
er precision the principal assumptions on 
which political computations are founded. 
The strict amount of the wealth of a coun- 
try cannot be known without an exact inven- 
tory of all the particulars that compose it, a 
thing utterly impracticable in large, and par- 
ticularly in commercial states, and which, if 
it were possible to be obtained perfectly true, 
even in the most minute particulars, would 
not remain so during the time necessary to 
make out the account, and therefore might 
not be of more utility than a tolerable correct 
estimate, which, being considered as a medi- 
um between small variations, will, for a con- 
si d< ruble time, furnish suffic ient ground for 
useful conclusions. So tar, indeed, are we 
from having exact accounts of the wealth of 
different countries, that even such of the ma- 
terials necessary to form an estimate as we do 
posse-s, though furnished pursuant to legisla- 
tive authority, are scarce, in any instance, 
strictly correct, and being generally formed 
tor particular purposes, as, with a view to 
some commercial or financial regulation, are 
frequently ill adapted to any other use: from 
such documents, however, we must be con- 
tent to draw our principal information ; and 
if the nature of the subject precludes strict 
demonstration, we may, at least, endeavour, 
by proceeding on rational grounds, to arrive 
at conclusions consistent with probability. 
Political arithmetic has been much culti- 
vated of late years in Germany, France, and 
other parts of Europe, but as its application 
to the wealth and strength of different states 
is very similar, we shall endeavour to illus- 
trate it in an attempt to determine the in- 
crease and present state of the national 
wealth of Great Britain, which will be consi- 
dered as consisting in the value of the land 
and of the stock, the latter term compre- 
hending all useful realizations of past indus- 
try, except improvements of the soil, which 
make part of the present value of the land ; 
and if the amount of the national capital can 
be ascertained, it will naturally lead to an in- 
vestigation of the general income, both as 
arising from sucli capital, and from the pro- 
fits of labour. 
In all inquiries of this kind, the state of the 
population of the country is an object of pri- 
mary importance ; for it is the number of in- 
habitants which a country maintains, that 
gives the land itself the chiet pah of its va- 
lue, of which we have many proofs in the 
former and present state of different parts of 
Europe, and in the rise of the value of land 
with the increase of population in our own 
island. That Great Britain is now more fully 
inhabited than in the early periods of its his- 
tory, few persons will doubt, whatever may 
be their opinion respecting its advance or de- 
cline in this respect of late years. At the timo 
of the Norman conquest, the people of Engr 
land are supposed to have been somewhat 
above 2,000,000; and from their depressed 
condition, the frequency of foreign and do- 
mestic wars, and of pestilential distempers, 
their increase during many of the succeeding 
reigns may be reasonably doubted, though 
there are no means of ascertaining with any 
precision the real state of the population at 
those periods. From an account of the pro- 
duce of a poll-tax, an estimate has been 
formed by Mr. Chalmers of the number of in- 
habitants in 1377, and as the additions which 
he has made to the number in the return cer- 
tainly do not appear loo small, the total, 
which ^mounts to 2,333,203, cannot be less 
than the whole number of the people ot Eng- 
land and Wales at that time, if the account on 
which it is founded is to be depended on, 
Mr. Chalmers observes, that the civil wars 
during the greater part of the fifteenth centu- 
ry must have caused a great waste of inhabit- 
ants : this loss, however, was soon recovered 
on their termination ; and the suppression of 
monasteries by Henry the VUIth, with the 
repeal of all positive laws against tjie marriage 
of priests by Edward the Vlth, continued to 
promote m .trimonv, and of course to increase 
the population. From documents in the 
British Museum, it appears, that during the 
reign of Elizabeth, accounts were often taken 
of the people. Harrison gives the result of 
the musters of 1373, when the number of 
fighting -.pen w® found to be 1,172,674, 
adding that it was believed a full third had 
been our ted. Sir Walter Raleigh asserts 
that there was a general review in 1583 of all 
the men in England capable of bearing arms, 
who were found to amount to 1,172,000. 
These accounts evidently refer to the sam<^ 
enumeration, though they differ in the date; 
and if the number is multiplied by 4, it would 
i 
