DOI Page / Citation link:
https://doi.org/10.11588/diglit.62828#0161
( i°5 )
curve, anfwerable to any fedion, through its center may be
found. I have not given any example of this on the Plate, as
it is prefumed that a few hints will ferve, after what has already
been faid on the fubjecft.
Operation.—Draw a circle whofe diameter ihall be equal
to the axis of the fphere to be covered. Divide the femi-
diameter into nine equal parts, and on thefe parts draw lines
acrofs at right angles with the diameter, till they touch the
circumference of the circle on each fide. From thefe feveral
lines draw femicircles, as was done before in Fig. 32 and 33.
Divide the feveral femicircles into eighteen degrees each, and
take one degree from the largeft femicircle, and place this
opening of the compaffes on a right line eighteen times. Then
from the extreme points on this line draw arches each way,
till they meet in the center of the line. Daftly, transfer half
a degree from each femicircle to ‘ their correfpondent arch,
laid on each way from the right line, as was done on No. 1,
Fig. 32; and the whole thus transferred, a curve line palling
through each half degree laid on the feveral arches both right
and left from the center line, will form the proper covering for
the fphere or globe as required.
Obferve, the covering will be of the figure of two feg-
inents of a circle joined together, and the length of the cover-
O ing
curve, anfwerable to any fedion, through its center may be
found. I have not given any example of this on the Plate, as
it is prefumed that a few hints will ferve, after what has already
been faid on the fubjecft.
Operation.—Draw a circle whofe diameter ihall be equal
to the axis of the fphere to be covered. Divide the femi-
diameter into nine equal parts, and on thefe parts draw lines
acrofs at right angles with the diameter, till they touch the
circumference of the circle on each fide. From thefe feveral
lines draw femicircles, as was done before in Fig. 32 and 33.
Divide the feveral femicircles into eighteen degrees each, and
take one degree from the largeft femicircle, and place this
opening of the compaffes on a right line eighteen times. Then
from the extreme points on this line draw arches each way,
till they meet in the center of the line. Daftly, transfer half
a degree from each femicircle to ‘ their correfpondent arch,
laid on each way from the right line, as was done on No. 1,
Fig. 32; and the whole thus transferred, a curve line palling
through each half degree laid on the feveral arches both right
and left from the center line, will form the proper covering for
the fphere or globe as required.
Obferve, the covering will be of the figure of two feg-
inents of a circle joined together, and the length of the cover-
O ing