at N, that point N is the point of Ration, or foot of the fpec-
tator.
I fhall conclude this fedtion with advifing the reader to
make himfelf well acquainted with the preceding planes, lines,
and points, before he proceed further: which, if he do, it will
enable him to read the fubfequent pages more ealily, and often
prevent the trouble of referring to the plates. Add to this, it
will make him underftand more readily the problems and ope-
rations of both this and other publications on the fubjedh
SECTION
tator.
I fhall conclude this fedtion with advifing the reader to
make himfelf well acquainted with the preceding planes, lines,
and points, before he proceed further: which, if he do, it will
enable him to read the fubfequent pages more ealily, and often
prevent the trouble of referring to the plates. Add to this, it
will make him underftand more readily the problems and ope-
rations of both this and other publications on the fubjedh
SECTION