D, extend your compaffes, and turn the arch g g ;
and with the fame extent, placing one foot in C,
defcribe the arch h h ; join the interferons with a
perpendicular from i to k ;. next, place one foot of
the compaffes in i, fweep the arch L L, and with-
out altering them, fet one foot in k, and defcribe the
arch M M.
8. Another method for an oval. See fig. IX.
Draw a given line A D, and with the compaffes
extended, placing one foot in B, with the other
turn the circle e e; then, without altering your
compaffes, on the line A D in the fuppofed point C'
fweep the circle f f, and through the points g g,
where the two circles interfeft, draw the perpen-
dicular h i; then fix your compaffes with one foot
in h, and extend them fo as to defcribe the arch
k k to the lower extremities of the circles; then,
with the fame extent, with one foot in i, fweep the
arch 1 1, to join the upper extremities.
By thefe examples it will appear, that an oval of
any form or fize may be conftrufted at pleafure, on-
ly taking care always to fix the compaffes equi-
diftant from the given line A D in the perpendicu-
lar h i.
PRACTICAL EXAMPLES in PERSPECTIVE.
1. To draw a fquare pavement in pcrfpeffivc. See fig. X.
Suppofe your piece of pavement to confift of fix-
ty-four pieces of marble, each a foot fquare. Your