INC 
contained between the planes of the equa- 
tor and ecliptic. Inclination of a planet, 
is an arch, of the circle of inclination, com- 
prehended between the ecliptic and the 
plane of a planet in its orbit. See Astro- 
nomy. 
INCLINED plane, in mechanics, one 
that makes an oblique angle with the hori- 
zon. If a force, with a given direction, 
supports a weight upon an inclined plane ; 
that force is to the weight, as the sine of 
the inclination of the plane to the sine of 
the angle which is made by the line in which 
the force acts, and the line perpendicular to 
the plane. See Mechanics. 
INCLOSURES. Any person who shall 
wilfully or maliciously demolish, pull down, 
or otherwise destroy or damage, any fence 
raised or made for dividing or inclosing any 
common, waste, or other lands, in pursuance 
of any act of parliament, or shall cause or 
procure the same to be done, shall be guilty 
of felony, and transported for seven years. 
Prosecution to be commenced in eighteen 
months after the offence committed. 
INCOMBUSTIBLE, something that 
cannot be burnt, or consumed by fire. 
Authors talk much of an incombustible 
cloth, made of the asbestus. See Asbes- 
TUS. 
INCOMBUSTIBLES, simple. See 
Substances, simple. 
INCOME tax, a direct contribution of a 
certain proportion of the annual gains of 
individuals for the public service, which has 
recently become an important branch of the 
revenue of Great Britain. An attempt was 
made in 1702 to levy a tax of this descrip- 
tion; but it proved very unproductive, and 
therefore was discontinued. Towards the 
end of the year 1798, Mr. Pitt proposed, in 
lieu of the additional assessed taxes, a gene- 
ral tax on income, whether arising from 
land, personal property, or from any pro- 
fession, office, trade, or other employment. 
The act was passed 9th January, 1799 ; and 
the duties imposed by it were, ten per cent, 
on all incomes of 2001. per annum and up- 
wards, and lesser proportions on incomes be- 
tween that amount and 601. per annum, which 
paid a one-hundred-and tw entieth part, or 
ten shillings per annum : incomes below 601. 
a year were wholly exempt. The great 
object of this tax was, to raise a consider- 
able proportion of the public supplies within 
the year, and to liquidate w ithin a short 
time what might be further raised by loan ; 
with the latter view the payment of the in- 
terest, and redemption of the capital, of 
INC 
part of the loans for the years 1798, 1799, 
and 1800, was charged on the produce of 
the tax ; but it being a tax which from its 
commencement had been very unpopular, 
both from its weight and the disclosure of 
the circumstances of individuals with which 
it was attended, it was repealed in April, 
1802, and the charges upon it transferred to 
the Consolidated Fund. 
In 1803 the income tax was revived, with 
some alterations in the mode of collecting 
it, under the title of the property tax : the 
rate at which it was now imposed was 5 
per cent, on all incomes above 1501. per 
annum, and lesser proportions on incomes 
between that amount and 601. per annum. 
In 1805 it was increased to 6| per cent. ; 
and in 1806 it was raised to the original 
rate at which it had been imposed, or 10 
per cent., while the scale of lesser rates was 
made to comprehend all incomes amounting 
to 501. per annum. By this means, and by 
deducting the tax on the dividends of the 
public funds at the Bank, and abolishing 
most of the former abatements and exemp- 
tions, the sum raised by it has been consi- 
derably augmented, the estimated produce 
being as follows : 
1804 at Is. in the pound £ 4,650,000 
1805 at Is. 3d. ditto 5,937,500 
1806 at 2s ditto 11,500,000 
An income tax, if it could be so regulated 
as to bear a just proportion to the different 
modes in which the incomes of individuals 
arise, and did not extend to such amounts 
of income as are absolutely necessary for 
subsistence, would become the most equi- 
table, as well as the most productive mode 
of taxation. 
INCOMMENSURABLE, a term in geo- 
metry, used where two lines, when compar- 
ed to each other, have no common measure, 
how small soever, that will exactly measure 
them both. And in general two quantities 
are said to be incommensurable, when no 
third, quantity can be found that is an ali- 
quot part of both. Such are the diagonal 
and side of a square; for though each of 
those lines have infinite aliquot parts, as the 
half, the third, &c. yet not any part of the 
one, be it ever so little, can possibly mea- 
sure the other, as is demonstrated in prop. 
117. lib. x. of Euclid. 
Incommensurable numbers are such as 
have no common divisor that will divide 
them both equally. 
INCOMPLETE, in botany, a term used 
to denote the sixteenth class of the Linnaean 
Oo 2 
