four harmonic points
from the point
ne


serreizelet! le polar


il pe,of course the ameter


ai
tl


comes to the same,to di


AC
25


the straieht line a


two points on the larger


as also of two other points


which


harmonic set


Ss


t 7
a+b ,a,a + b,and


ines,as the basis of


armonic sets of four elements


e conjugate elements of one


of the second pair.
such har
the sum
components of


or
therefore


the


four elements


Le that


s) and
form


ame as


se
+ a + b)(a+n)
-+ a' b)
+ 2 a 1 is ab)
T (a + b)(a+b
N last a'b )
It is necessary,also,to add the limitary harmonic series,the thir
teenth on the straight line at infinity.
tet} ds PA (¿Aa aa e By
If we now recall that algebraic expressions signify here not only
geometrical elements (straight lines and points) but also concepts,the
existence of harmonic sets of four elements in geometrical logic is the
lemonstrated.
