0.5

1 cm

L 54 3

by uniting A and I, the intersefftion gives B a for the

length of B A : but as D I, if united, yet continues a

mere line, we mull find others to cut off its proportion:

unite E to the ground line, by a line in any direction,

and by a parallel line unite D ; then by a parallel from I

toHL we obtain a point, to which, when the inter-

seclions of D and E on the ground line are united,

they give d e for the representation of D E.

No. HE A square is composed of four Tides, two

perpendicular to the other two : if supposed to be situated

with two Tides parallel to the picture, it is evident that

the two other sides will be perpendicular to that picture :

These may be considered as two lines placed as in the

foregoing example, which naturally vanish in C, to

which therefore unite them : to determine their lengths

seen in perspective, rule a diagonal line from the oppo-

sife corners of the original square, which line unite to

the ground line ; rule its parallel from I to H L, and

unite its seat on the ground line to that point in H L

so procured; its interseclions will cut one line of the

two drawn to C in its nearest part, and the other line

in its furthesl part from these interseclions, lines parallel

to H L will complete the figure. E. gr. A B D E

is an original square; produce A D and BE to

the ground line, these vanilh in C ; produce also A E

to the ground line, this vanishes in its parallel I L,

and gives a d b e for the representation of A D

B E.

N. B. The diagonal of a square being naturally, 44

degrees, if an angle of 45 degrees be made srom I and

continued to H L (as at L), it will give L for the va-

jiishing point of such a line, without the necessity of

recurring to the original figure.

No*

by uniting A and I, the intersefftion gives B a for the

length of B A : but as D I, if united, yet continues a

mere line, we mull find others to cut off its proportion:

unite E to the ground line, by a line in any direction,

and by a parallel line unite D ; then by a parallel from I

toHL we obtain a point, to which, when the inter-

seclions of D and E on the ground line are united,

they give d e for the representation of D E.

No. HE A square is composed of four Tides, two

perpendicular to the other two : if supposed to be situated

with two Tides parallel to the picture, it is evident that

the two other sides will be perpendicular to that picture :

These may be considered as two lines placed as in the

foregoing example, which naturally vanish in C, to

which therefore unite them : to determine their lengths

seen in perspective, rule a diagonal line from the oppo-

sife corners of the original square, which line unite to

the ground line ; rule its parallel from I to H L, and

unite its seat on the ground line to that point in H L

so procured; its interseclions will cut one line of the

two drawn to C in its nearest part, and the other line

in its furthesl part from these interseclions, lines parallel

to H L will complete the figure. E. gr. A B D E

is an original square; produce A D and BE to

the ground line, these vanilh in C ; produce also A E

to the ground line, this vanishes in its parallel I L,

and gives a d b e for the representation of A D

B E.

N. B. The diagonal of a square being naturally, 44

degrees, if an angle of 45 degrees be made srom I and

continued to H L (as at L), it will give L for the va-

jiishing point of such a line, without the necessity of

recurring to the original figure.

No*