The artists repository and drawing magazine: exhibiting the principles of the polite arts in their various branches (4.1790)

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the lefs will be the fpace or compafs of the plan or per.-
fpective view.

The third phenomenon is, that the image or picture of
the object is inverted ; and this is not the effe£t of the
glafs, but the croffing of the rays in the hole through
which they pafs into the room ; for if a'very fmall hole
were made in the window-fhutter of a darkened rooms
the objects without would be all feen inverted, thofe
which come from the upper part of the object going to
the lower part of the image, and vice verfa. All that
the glafs does is to render the image diftinct, by con-
verging the rays of every pencil to their proper focus in
the picture, the pofition of each point being the fame as
before.

The. fourth phenomenon is the motion or reft of the
feveral parts of the picture, according as thofe of the
object are in either ftate. The reafon of this is very
obvious ; and this it is that gives life and fpirit to the
painting and portraits of nature, and is the only parti-
cular inimitable by art. And indeed a more critical idea
may be formed of any movement in the picture of a
darkened room, than from obferving the motion of the
object.itfelf: For inftance, a man walking in a picture
appears to have an undulating motion, or to rife up
and down every ftep he takes ; whereas nothing of this
kind is obferved in the man himfelf, as viewed by the
bare eye.

The fifth phenomenon is the colouring of the optic pic-
ture % every piece of imagery has its proper tints and
colours, and thofe always heightened and rendered more
intenfe than in the objecl; fo that in this refpeel it is

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