Now for K: You are to make the first tract vertical, in the same manner
as you formerly did for H; then draw another narrower limb from the
broader and erect one, so that it may, at its lower end, impinge
obliquely on the transverse line e. f. and above may ascend to the right
till it meet the line a. b., taking care to make it parallel to the
diagonal c. b.; and this, at the top, you are to produce in both
directions so that each production may represent a tenth part of the
line a. b. The hitherward projection you are to round out with a circle
of which the diameter must not exceed the breadth of the lesser limb;
but of the other arc, by means of which you round out the farther
projection, you shall make the diameter double as great as the diameter
of the arcs by which you have customarily hollowed out the preceding
extensions of the broad and vertical limbs. Next, from the narrow limb
so constructed draw in a downward direction another broad limb, so that
it too may be parallel to a diagonal of the square; & of this the
beginning is to be taken from the acute angle which the narrower limb
makes with the broad vertical limb, and let it be drawn with its
projection to the angle d., yet in this fashion: take two points this
side of d. after this manner, so that the first point may be distant
from d. the tenth part of the line c. d. & the second as far again from
the first; then let the said tract be drawn within the space which is
between the two points, but in blind and invisible lines. Afterwards you
shall add the extension, which you shall make this way: take before f.
in the line e. f., a point g. no farther distant from f. than the
breadth of the narrower limb; on this point set one leg of your compass,
& let the other be extended to the angle d., from which let it be guided
back along the broad but invisible blind limb: thence will result the
lower convexity of the tail you seek; but its upper concavity look for
in this way: divide f. d. in its middle point h.; on this set one leg of
your compass, and with the other describe an arc passing through d. to
meet the broad limb.
Or you may make K in this manner: First, let your broader vertical limb,
and your upper narrow one remain as they have been described, except
that the interior angle which the narrower limb forms with a. b. shall
remain acute, but the exterior one shall be rounded out, as has been
said. Then let there be drawn the lower broad limb, obliquely from the
angle which is included between e. f. and the vertical limb, and let it
descend to meet the side c. d. so that between d. and the limb the width
of the limb be left vacant; and the hither angle is to be left, but the
farther, towards d., shall be rounded out a little, as shown below.
[Illustration: K]