PRA 
To raise any simple quantity to its second, 
third, or fourth power, is to add its expo- 
nent twice, thrice, or four times to itself ; 
so that the second power of any quantity is 
had by doubling its exponent j and the 
third, by tripling its exponent ; and, in ge- 
neral, the power expressed by m, of any 
quantity, is had by multiplying the exponent 
by in : thus the second power, or square of 
a, is ; its third power, a’ 
and the with power of a, is a® ‘ Also 
tlie square of «*, is " = a® ; the cube of 
a^, is ; and the mth power of o'", 
is The square of abc, is a® ¥ its 
cube o® b' ¥ ; and the mth power, a" b"' c'". 
POX, or Small Pox. See Medicine. 
PRACTICE, in arithmetic, or rules of 
practice, are certain compendious ways of 
working the rule of proportion, or golden- 
rule. 
I. When a question in the rule of three 
being duly stated, and the extremes are 
simple numbers of one name ; whether the 
middle term be simple or mixed ; if the 
extreme, which by the general rule is the 
divisor, he 1, and the middle term, an 
aliquot part, of some superior species ; 
then divide the other extreme by the deno- 
minator of that aliquot part, the quote is the 
answer in that superior species; and if 
there is any remainder, it must be reduced, 
and its value found. Example. What is the 
price of 67 yards of cloth at .Ss.'per yard f 
The state of the proportion is, as 1 yard : 
5s. : ; 67 ; and because the divisor is 1 
yard and the middle term 5s. which is a 
fourth part of one pound. Therefore divide 
67 yards by 4, the quote is 161. and 3 re- 
mains, which reduced to shillings, and di- 
vided by 4, quotes t5s. 
The reason of this practice is obvious ; 
for if 1 yard costone-fourth of 11. 67 yards 
must cost 67^th parts, or, which is the same 
thing, the fourth part of 671. 
II. If the price of an unit is an even 
number of shillings, multiply the other ex- 
treme (of the same name with the unit) by 
the half of that number ; double the first 
figure of the product for shillings, and the 
remaining figures to the left, are pounds in 
the answer. Example. What is the value of 
324 yards at 6s. per yard i Multiplying 324 
by 3 (the one-half of 6) the product is 972, 
which according to tlie rule, is 971. 4s. 
which is the answer. And it is very easy to 
set down the shillings and pounds sepa- 
rately, without writing first down the total 
product, and then separating them. 
III. If the middle term is not an aliquot 
PR(E 
part of some superior integer, (the divisor , 
being always 1), yet it may be equal to the 
sum of several aliquot parts ; and then if you 
divide by the denominators of each of 
these separately, and add all the quotes, the 
same is the answer required. Example. If 
1 yard cost 15s. what cost 49 yards ? 
Answer 361. 13s. : found tluis ; 1,5s. is 10s. 
and 5s. m. the one-half and one-fourth of a 
11. so I take the one-half of 491. which is 
241.10s. and one fourth, which is 121. 5s. 
whose sum is 361. 15s. 
IV. If the middle term is so mixed as 
to have in it any number of the highest spe- 
cies, tirst multiply the number, and then the 
other parts by some of the former cases, if 
possible, and if this cannot be done, or not 
without much w^orkirig ; tlien the common 
method of reduction is to be taken. Exam- 
ple. If 1 yard cost 4l. 6s. 8d. what cost 734 
yards? Answer 3,1801. 15s. 4(1. for 41. multi- 
plied by 734, produces 2,9361. and Tor 
6s. Sd. which is the one-third of 11. you 
must take the one-third of 734, which is 
2441. 15s. 4(1. and the sum of both is 
3,1801. 13s. 4(1. 
V. If the extreme which is the mul- 
tiplier is an aliquot part, or the sum of cer- 
tain aliquot parts, of the unit, which is the 
divisor, then take by division such part or 
parts of the middle term (whether this be a 
simple, or mixed number) and if the mul- 
tiplier has also some number of the same 
species wdth the unit, you must work for 
that number separately by some of the 
former cases, or the common rule; then 
add all the parts, which is the answer. 
Example 1. If 1 pound weight cost 321. 
what cost 4 ounces ? Answer 81. viz. one- 
fourth of 321. because 4 ounces are one- 
fourth of 1 pound. 
These are the chief and fundamental 
practices by aliquot parts, which, whoever 
understands, will easily find many particu- 
lar abridgments depending upon the same 
principles. 
PRiECIPE, is the name of several writs 
in the English law, which are so called 
from the form of commanding the defendant 
to do the thing required. 
PRiEMUNIRE, is a punishment in- 
flicted upon him who denies the King’s su- 
premacy the second time ; upon him who 
affirms the authority of the Pope, or re- 
fuses to take the oath of supremacy ; upon 
such as are seditious talkers of the inhe- 
ritance of the crown ; and upon such as af- 
firm that there is any obligation by any 
oath, covenant, or engagement whatsoever, 
