IMP 
the third divided by the second gives § also ; 
hence these quotients, placed over the in- 
termediate terms, the whole will stand 
thus : 
i i 
X s — 4 x 1 -f- 4 x — 6. 
+ + — + 
Now because the square of the second 
term, multiplied by its superscribed frac- 
tion, is w x 4 , which is greater than 4 x 4 , 
the product of the two adjacent terms, 
therefore the sign -)- is set below the se- 
cond term ; and because the square of the 
third term, multiplied by its over written 
fraction, is 'j x 1 , which is less than 24 x 2 , 
the product of the terms on each side of it ; 
therefore the sign — is placed under that 
term ; also the sign -{- is set under the first 
and last terms. Hence the two changes of 
the underwritten signs + + -+, the one 
from -j- to — , and the other from — to -J-, 
show that the given equation has two impos- 
sible roots. When two or more terms are 
wanting together, under the place of the 
first of the deficient terms write the sign — 
under the second the sign -j-, under the 
third — , and so on, always varying the 
signs, except that under the last of the defi- 
cient terms must always be set the sign +> 
when the adjacent terms on both sides of 
the deficient terms have contrary signs. 
As in the equation. 
x' J -f ax 4 # # # -f- «s — o, 
+ + — 4 — + 
which has four imaginary roots. 
IMPOSTS, in architecture, the capitals 
of pillars, or pilasters, which support arches. 
An impost, sometimes called chaptrel, is a 
sort of a plinth, or little corniche, which 
crowns a pier, and supports the first stone 
whence an arch or vault commences. The 
imposts are conformable to their proper 
orders. The Tuscan has only a plinth; the 
Doric has two faces crowned ; the Ionic, a 
larmier, or crown over the two faces, and 
its mouldings may be carved ; the Corin- 
thian and Composite have a larmier, frieze, 
and other mouldings. See Architecture. 
IMPOTENCY, in the ecclesiastical law, 
signifies an inability of generation, or pro- 
pagating the species, which is a cause of 
divorce a vinculo matrimonii, as being mere- 
ly void, and therefore needs only a sentence 
declaratory of its being so. 
IMPRESSING men. The power of 
impressing seamen for the sea-service, by 
the King’s Commission, has been a matter 
of some dispute, and submitted to with 
great reluctance, though it lias very clearly 
VOL. III. 
IMP 
and learnedly been shown by Sir Michael 
Forster, that the practice of impressing, 
and granting power to the Admiralty for 
that purpose, is of very ancient date, and 
has been uniformly continued, by a regular 
series of precedents, to the present time, 
whence he concludes it to be part of the 
common law. The difficulty arises from 
hence, that no statute has expressly de- 
clared this power to be in the crown, 
though many of them very strongly imply it. 
r lhe statute 2 Richard II. c. 4, speaks of 
mariners being arrested and retained for 
the King’s service, as of a thing well known 
and practised without dispute, and provides 
a remedy against their running away. By 
statute 2 and 3 Philip and Mary c. 16, if 
any waterman who uses the river Thames, 
shall hide himself during the execution of 
any commission for pressing for the'King’s 
service, he is liable to heavy penalties. By 
statute 5 Elizabeth, c. 6, no fisherman shall 
be taken by the Queen’s commission to serve 
as a mariner ; but the commission shall be 
first brought to two justices of the peac* 
inhabiting near the sea coast where the ma- 
riners are to be taken, to the intent that 
the justices may choose out, and return 
such a number of able bodied men as in the 
commission are contained to serve her 
Majesty. And by statute 7 and 8 William, 
c. ,21 ; 2 Anne, c. 6 ; 4 and 5 Anne, c. 19 ; 
13 George II. c. 17, especial protections 
are allowed to seamen in particular circum- 
stances, to prevent them from being im- 
pressed. All which do most evidently imply 
a power of impressing to reside somewhere ; 
and if any where, it must, from the spirit of 
our constitution, as well as from the fre- 
quent mention of the king’s commission, 
reside in the crown alone. The Liverymen 
of London claim an exemption from be- 
ing pressed; but by a -late decision of the 
Court of King’s Bench, this exemption is 
denied. Landmen, entering into the mer- 
chant service, and apprentices, are ex- 
empt for two years from the impress, and 
all apprentices to the sea-service under 
eighteen. 
IMPRESSION denotes the edition of 
a book, regarding the mechanical part 
only; whereas edition, besides this, takes 
in the care of the editor, who corrected or 
augmented the copy, adding notes, &c. to 
render the work more useful. 
IMPRISONMENT, is the restraint of 
a man’s liberty under the custody of ano- 
ther, and extends not only to a gaol, but an 
house, stocks, or where a man is held in the 
O o 
