DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.19575#0168
PER 153
portion, both in magnitude and diftance, in draught, which ap-
pears from the object to the eye.
15. In colouring and fhadowing of every thing, you muft do
the fame in your picture, which you obferve with your eye, ef-
pecially in objects lying near ; but, according as the diftance
grows greater and greater, fo the colours muft be fainter and
fainter, till at laft they lofe themfelves in a darkifh fky colour.
16. The catoptrics are beft feen in a common looking-glafs,
or other polifhed matter; where, if the glafs be exactly flat, the
object is exactly like its original; but if the glafs be not flat, the
refemblance alters from the original; and that, more or lefs, ac-
cording as the glafs differs from an exact plane.
17. In drawing catoptric figures, the furface of the glafs is to
be considered, upon which you mean to have the reflection :
For which you muft make a particular ichnographical draught
or projection ; which on the glafs muft appear to be a plain full
of fquares, on which projection transfer what fhall be drawn on
a plane, divided into the fame number of like fquares; where,
though the draught may appear very confufed, yet the reflection
of it on the glafs will be very regular, proportional, and regularly
compofed.
18. The dioptric or broken beam may be feen in a tube thro'
a cryftal or glafs, which hath its furface cut into many others,
whereby the rays of the object are broken.
For to the flat of the cryftal or water the rays run ftraight;
but then they break and make an angle, the which alfo by the re-
fracted beams is made and continued on the other fide of the
fame flat.
19. When thefe faces on a cryftal are returned towards a plane
placed directly before it, they feparate themfelves at a good dif-
tance on the plane ; becaufe they are all directed to various far
diftant places of the fame
20. But, for the affigning to each of them a place on the fame
plane, no geometric rule is yet invented.
Of the ujes of Perspective. 1. Perfpective then is a fcience
or rather an art abfolutely neceftary to one who would draw well,
engrave, etch, carve, or paint; and which men of thofe pro-
feffions ought not to want: Yet they are not to be fo wholly fub-
ject to its precepts, as to enflave thefe arts to its rules.
2. It is to be ufed when it leads you pleafingly into the beau-
ties of your work, and can be helpful to you in your defign ;
but, when it will not be ufeful to thefe purpofes, you are to pafs
it by, left it fhould mifguide you, by leading you to fomething
that is repugnant to your peculiar art.
3. Perfpective cannot of itfelf be called a certain rule, but it
js to be ufed with judgment, prudence, and difcretion ; for if it
be
portion, both in magnitude and diftance, in draught, which ap-
pears from the object to the eye.
15. In colouring and fhadowing of every thing, you muft do
the fame in your picture, which you obferve with your eye, ef-
pecially in objects lying near ; but, according as the diftance
grows greater and greater, fo the colours muft be fainter and
fainter, till at laft they lofe themfelves in a darkifh fky colour.
16. The catoptrics are beft feen in a common looking-glafs,
or other polifhed matter; where, if the glafs be exactly flat, the
object is exactly like its original; but if the glafs be not flat, the
refemblance alters from the original; and that, more or lefs, ac-
cording as the glafs differs from an exact plane.
17. In drawing catoptric figures, the furface of the glafs is to
be considered, upon which you mean to have the reflection :
For which you muft make a particular ichnographical draught
or projection ; which on the glafs muft appear to be a plain full
of fquares, on which projection transfer what fhall be drawn on
a plane, divided into the fame number of like fquares; where,
though the draught may appear very confufed, yet the reflection
of it on the glafs will be very regular, proportional, and regularly
compofed.
18. The dioptric or broken beam may be feen in a tube thro'
a cryftal or glafs, which hath its furface cut into many others,
whereby the rays of the object are broken.
For to the flat of the cryftal or water the rays run ftraight;
but then they break and make an angle, the which alfo by the re-
fracted beams is made and continued on the other fide of the
fame flat.
19. When thefe faces on a cryftal are returned towards a plane
placed directly before it, they feparate themfelves at a good dif-
tance on the plane ; becaufe they are all directed to various far
diftant places of the fame
20. But, for the affigning to each of them a place on the fame
plane, no geometric rule is yet invented.
Of the ujes of Perspective. 1. Perfpective then is a fcience
or rather an art abfolutely neceftary to one who would draw well,
engrave, etch, carve, or paint; and which men of thofe pro-
feffions ought not to want: Yet they are not to be fo wholly fub-
ject to its precepts, as to enflave thefe arts to its rules.
2. It is to be ufed when it leads you pleafingly into the beau-
ties of your work, and can be helpful to you in your defign ;
but, when it will not be ufeful to thefe purpofes, you are to pafs
it by, left it fhould mifguide you, by leading you to fomething
that is repugnant to your peculiar art.
3. Perfpective cannot of itfelf be called a certain rule, but it
js to be ufed with judgment, prudence, and difcretion ; for if it
be