DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.18826#0013
I*ECT. I.] ON PERSPECTIVE* 7
every object delineated on it appears inverse.;, what is
really above, seems below ; what is really to the right
hand, seems to be to the left.
This inversion of objects is very distinctly seen in
the dissected eye of a large quadruped, an ox,, or a
horse ; and very beautiful, indeed, it is to behold :
but perhaps the same effect is more famiiiar to my
auditors, from occasional observations they must
have made, on the transmission of luminous rays
through a small hole, or crevice, into a dark cham-
ber. In this case, external objects, or the effects of
external objects, become depicted on the opposite
wall of the chamber, inversely with respect to the
actual situation of such objects ; thus,, if the perfor-
ation be next a street, the approach of passengers is,
as it were, announced, by a ray which strikes the
part opposite to that whereon they are situated : for
the supposed crevice being far too small to afford
passage for the rays emitted from every part of an
object, becomes a centre to those rays whose diffe-
rent directions permit them to converge. Therefore,
•the ray from above, continuing its natural course in
a straight line, necessarily strikes, in the chamber,
somewhere below ; as the ray from below necessarily
strikes somewhere above : its direction not being
■altered by its passing through the orifice; though
*ts quantity, may be diminished.
How then do we acquire the faculty of distinguish-
ing the actual situations of objects ? By habit; by the
exercise of another sense (I mean Touching), as ano-
ther medium of obtaining certainty. This habit
commences much too early in life for us to notice
B 2 its
every object delineated on it appears inverse.;, what is
really above, seems below ; what is really to the right
hand, seems to be to the left.
This inversion of objects is very distinctly seen in
the dissected eye of a large quadruped, an ox,, or a
horse ; and very beautiful, indeed, it is to behold :
but perhaps the same effect is more famiiiar to my
auditors, from occasional observations they must
have made, on the transmission of luminous rays
through a small hole, or crevice, into a dark cham-
ber. In this case, external objects, or the effects of
external objects, become depicted on the opposite
wall of the chamber, inversely with respect to the
actual situation of such objects ; thus,, if the perfor-
ation be next a street, the approach of passengers is,
as it were, announced, by a ray which strikes the
part opposite to that whereon they are situated : for
the supposed crevice being far too small to afford
passage for the rays emitted from every part of an
object, becomes a centre to those rays whose diffe-
rent directions permit them to converge. Therefore,
•the ray from above, continuing its natural course in
a straight line, necessarily strikes, in the chamber,
somewhere below ; as the ray from below necessarily
strikes somewhere above : its direction not being
■altered by its passing through the orifice; though
*ts quantity, may be diminished.
How then do we acquire the faculty of distinguish-
ing the actual situations of objects ? By habit; by the
exercise of another sense (I mean Touching), as ano-
ther medium of obtaining certainty. This habit
commences much too early in life for us to notice
B 2 its