it below nothing, as many times as there 
are units in the multiplier; therefore the 
product muft neceflarily be a negative quan- 
tity. 
But you will afk, what is the reafon that 
when two negative quantities are multiplied 
by each other, the product muft have a po- 
fitive fign ? The reafon is plain : for, if to 
multiply by a negative quantity be to fub- 
tract, then fuch multiplication is actually 
fubtracting from the Debtor page of my ac- 
count-book, which has the fame effect as if 
the fum were added to the Creditor fide. To 
fubtract minus is the fame thing as to add 
plus. If I difcharge, or take away your 
debt of a guinea at the fruit-mop, it is cer- 
tainly equivalent to my giving you a guinea. 
But before I conclude this introduction to 
Multiplication for it is no more than an 
introduction it is neceffary to obferve, 
that the multiplier, whether it be a pofitive 
or a negative quantity, or, whatfoever it 
may be called, is always nothing more than 
a number, without any real denomination. 
A pound cannot be multiplied by a pound, 
nor a mile by a mile. 
LET- 
