213108An ESSAY
nearly equal to the Height of the Top of the
Machine above the Table: Then we open the
Aperture N at the Back-part of the Box upon the
Machine; and incline the Mirrour L, ſo as to make
an Angle of 45 deg. with the Horizon, when Ob-
jects are to be repreſented for the perpendicular
Picture. Then, if the Mirrour H be taken away,
as alſo the Board F, together with the two Ru-
lers D E and D E, we ſhall perceive the Repre-
ſentation upon the Sheet of Paper on the Table
A, of all Objects, whoſe Rays falling upon the
Looking-glaſs L, can be thereby reflected upon
the Convex Glaſs; which Convex Glaſs muſt be
rais’d or lower’d, by means of the Screw about
the Cylinder carrying it, until the ſaid Objects
appear entirely diſtinct.
Machine above the Table: Then we open the
Aperture N at the Back-part of the Box upon the
Machine; and incline the Mirrour L, ſo as to make
an Angle of 45 deg. with the Horizon, when Ob-
jects are to be repreſented for the perpendicular
Picture. Then, if the Mirrour H be taken away,
as alſo the Board F, together with the two Ru-
lers D E and D E, we ſhall perceive the Repre-
ſentation upon the Sheet of Paper on the Table
A, of all Objects, whoſe Rays falling upon the
Looking-glaſs L, can be thereby reflected upon
the Convex Glaſs; which Convex Glaſs muſt be
rais’d or lower’d, by means of the Screw about
the Cylinder carrying it, until the ſaid Objects
appear entirely diſtinct.
16.
When the ſame Objects are requir’d to be
repreſented for the inclin’d Picture, the Looking-
glaſs L muſt have half the Inclination we would
give to the Picture.
repreſented for the inclin’d Picture, the Looking-
glaſs L muſt have half the Inclination we would
give to the Picture.
17.
When the ſaid Objects are to be repreſent-
ed upon the Picture being parallel, the Aperture
N muſt be ſhut, and the Door B open’d; then
the Mirrour H muſt be rais’d to the Top of the
Box, in putting it in a Situation parallel to the
Horizon. This Diſpoſition of the Machine may
ferve when one is upon a Balcony, or ſome
other high Place; to deſign a Parterre under-
neath.
ed upon the Picture being parallel, the Aperture
N muſt be ſhut, and the Door B open’d; then
the Mirrour H muſt be rais’d to the Top of the
Box, in putting it in a Situation parallel to the
Horizon. This Diſpoſition of the Machine may
ferve when one is upon a Balcony, or ſome
other high Place; to deſign a Parterre under-
neath.
18.
If we have a mind to deſign a Statue
ſtanding in a Place ſomething elevated, and it is
requir’d to be ſo repreſented, as to be painted
againſt a Cieling; the Back-ſide of the Machine
muſt be turned towards the Statue, and the Box
X ſo turned, that the Door B may face the Sta-
tue; then, the Door being open’d, the Looking-
glaſs L muſt be placed vertically, with its po-
liſh’d Side towards the Statue; and the Box
ſtanding in a Place ſomething elevated, and it is
requir’d to be ſo repreſented, as to be painted
againſt a Cieling; the Back-ſide of the Machine
muſt be turned towards the Statue, and the Box
X ſo turned, that the Door B may face the Sta-
tue; then, the Door being open’d, the Looking-
glaſs L muſt be placed vertically, with its po-
liſh’d Side towards the Statue; and the Box
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