DOI Page / Citation link:
https://doi.org/10.11588/diglit.18826#0032
26 ON PERSPECTIVE. [lECT. I.
of St. Paul's Church ; where, by means of this corres-
pondence, we mould enjoy a more extenfive profpecf.
The fame effect, inverted, would follow our defceut :
we mould firft lofe fight of what was lately our hori-
zontal plane, and all things lying on it, would difap-
pear; the fame effect would attend that which in fuc-
ceflion became our horizontal plane, till we came to
the level of the ground itfelf; and the ground itfelf
would alfo yield to this principle, if we had occafion
to defcend ftill lower, as into a kitchen, into a well,
into a deep pit, or into a coal mine.
Again, the ground whereon a fpecrator (lands, is
a natural plane : now if we fuppofe a fpecrator to re-
main fixed, while all the fpace from before him to
the horizon, is gently raifed up vertically, when it has
rifen to the level of his eye, he will not be able any
longer to difcover objects fituated upon it; they are
precluded from his fight, and, together with the ground
plane itfelf, they form a mere line; or they vanifh : it
follows, that the line formed by the horizon, is the
vanishing line to the ground plane. Or, change the
fuppofition, and imagine the ground to maintain its
{lability, while a fpecrator defcends 3 as he goes lower,
and lower, the diftance between the horizon and the
ground diminifhes, till at length thefe two planes ap-
pear to him to unite. But there is no need for ima-
gining fuch high afcents, or fuch deep defcents ; an
inftance at hand may affift in demonftrating this prin-
ciple.
On this drawing board, we fee nozo from end to
end; but as I elevate it (yet keeping it horizontal),
when it is equal in height to the eye, we dilcern not
any
of St. Paul's Church ; where, by means of this corres-
pondence, we mould enjoy a more extenfive profpecf.
The fame effect, inverted, would follow our defceut :
we mould firft lofe fight of what was lately our hori-
zontal plane, and all things lying on it, would difap-
pear; the fame effect would attend that which in fuc-
ceflion became our horizontal plane, till we came to
the level of the ground itfelf; and the ground itfelf
would alfo yield to this principle, if we had occafion
to defcend ftill lower, as into a kitchen, into a well,
into a deep pit, or into a coal mine.
Again, the ground whereon a fpecrator (lands, is
a natural plane : now if we fuppofe a fpecrator to re-
main fixed, while all the fpace from before him to
the horizon, is gently raifed up vertically, when it has
rifen to the level of his eye, he will not be able any
longer to difcover objects fituated upon it; they are
precluded from his fight, and, together with the ground
plane itfelf, they form a mere line; or they vanifh : it
follows, that the line formed by the horizon, is the
vanishing line to the ground plane. Or, change the
fuppofition, and imagine the ground to maintain its
{lability, while a fpecrator defcends 3 as he goes lower,
and lower, the diftance between the horizon and the
ground diminifhes, till at length thefe two planes ap-
pear to him to unite. But there is no need for ima-
gining fuch high afcents, or fuch deep defcents ; an
inftance at hand may affift in demonftrating this prin-
ciple.
On this drawing board, we fee nozo from end to
end; but as I elevate it (yet keeping it horizontal),
when it is equal in height to the eye, we dilcern not
any