(6i3) 
added the Produft of d^ "" by the Letter whofe Exponent 
is r+i Tis becaufe the Sum of the Exponents is fti51 
As for what relates to the Vncice ; obfetve that when 
you Multiply az-^-lzz-^-tz^-^-dz^ , ^c, by az'\'lz%\cz^ 
Jz^y each Letter a, I, r, &c, of the i** Series 
is Multipli'd by each of the Letters c, of 
the i^^ Series ; Thus the Letter a of the Scries is Mul- 
tipli'd by the letter I of the r^, and the tetter I of 
he Series is Multipli'd by the Letter a of rhe ; 
therefore you have the z Planes, ai^ al or zah ; for the 
fame reafon you have zac, zady &c. Therefore you muft 
prefix to each Plane of thofe that compofe the Square of 
the Infinite Series az+lzz-^-cz'^ , &c. the Number which 
expreffeshow many ways the Letters of each Plane may 
be changed ; Likewife if you Multiply the Produd of 
the two prececding Series by az-V hzz^cz"^ , &c. each 
Letter a, c, of the 3*^ Series is Multiplied by each 
of the Planes form'd by the Produft of the i'^^ and z^ 
Series ; Thus the Letter a is Multiplied by the Planes h 
and cl ; the Letter b is Multiplied by ac and ca the 
Letter c is Multiplied by al and la ; therefore you 
have the 6 Solids, alc^ acb^ hac^ hca^ cab^ cla, or 6abc ; 
Therefore you muft prefix to each Solid whereof the 
Cube of the Infinite Series is compos'd, the Number 
which expreilcs how many ways the Letters of each 
Solid may be Changed. And generally, Tm mufl pre- 
fix to any Produil whereof any Power of the Infinite Series 
aZ'\'bzZf\'Cz^ , &c. is composed the dumber which expreffes 
how many ways the Letter of each Produ£l way be changed. 
Now to find how many ways the Letters of any Pro- 
dudl, for inftances a'^'^b^'cPd'' may bechanged ; this is the 
Rule which is commonly given : write as many terms 
of the Series 1x1x3x4x5', &c. as there are Units irr 
the Sum of the Indices,i//2. w — n-^hJ^p-^-r^ let this Series 
Xzzz z be 
