211106An ESSAY
the Back-ſide thereof hath in it a Square ope-
ning N, each Side being about four Inches in
Length, which may be ſhut by the little Board I
ſliding between two Rulers.
ning N, each Side being about four Inches in
Length, which may be ſhut by the little Board I
ſliding between two Rulers.
11.
Overthe ſaid Square opening, there is a Slit
parallel to the Horizon, going along the whole
Breadth of the Back-ſide of the Box; through
which Slit, a little Mirrour or Looking-Glaſs is to
be put into the Box, whoſe two Sides may ſlide be-
tween two Rulers ſo placed, that the poliſhed
Side of the Glaſs being turn’d towards the Door
B, may make an Angle of 112 {1/2} Degrees, with
the Horizon. Note, This Diſpoſition of the
Looking-glaſs could not well be repreſented in
the Figure.
parallel to the Horizon, going along the whole
Breadth of the Back-ſide of the Box; through
which Slit, a little Mirrour or Looking-Glaſs is to
be put into the Box, whoſe two Sides may ſlide be-
tween two Rulers ſo placed, that the poliſhed
Side of the Glaſs being turn’d towards the Door
B, may make an Angle of 112 {1/2} Degrees, with
the Horizon. Note, This Diſpoſition of the
Looking-glaſs could not well be repreſented in
the Figure.
12.
The before-mention’d Mirrour hath a ſmall
Iron Plate, on the Middle of that Side which is
without the Box, (when the ſaid Looking-glaſs
is in the Diſpoſition mention’d in N. 11.) being the
Baſe of a Screw faſten’d to the Middle thereof, that
ſothe Looking-glaſs may be fix’d upright (as appears
per Figure) in any Place H upon the Top of the
Machine, and vertically turn all ways; and this
is done by putting the Screw through a Hole
made in the plain Board of N. 9. and through a
Slit made for this End in the plain Board of N. 8.
and then fixing it with the Nut R. Now when
the Mirrour is taken from this Situation, the ſaid
Slit is ſhut by a ſmall Board ſliding between two
little Rulers within the Machine. As to the Slit
mention’d N. 11. it is partly ſhut by the little
Board I, when the Aperture N is open’d, and the
two Ends thereof remaining open’d, are ſhut by
two ſinall Rulers.
Iron Plate, on the Middle of that Side which is
without the Box, (when the ſaid Looking-glaſs
is in the Diſpoſition mention’d in N. 11.) being the
Baſe of a Screw faſten’d to the Middle thereof, that
ſothe Looking-glaſs may be fix’d upright (as appears
per Figure) in any Place H upon the Top of the
Machine, and vertically turn all ways; and this
is done by putting the Screw through a Hole
made in the plain Board of N. 9. and through a
Slit made for this End in the plain Board of N. 8.
and then fixing it with the Nut R. Now when
the Mirrour is taken from this Situation, the ſaid
Slit is ſhut by a ſmall Board ſliding between two
little Rulers within the Machine. As to the Slit
mention’d N. 11. it is partly ſhut by the little
Board I, when the Aperture N is open’d, and the
two Ends thereof remaining open’d, are ſhut by
two ſinall Rulers.
13.
There are two Iron Staples on one Side of
the Box, like thoſe which are on the 117. of the Machine; in which a Ruler going ſeveral
Inches out behind the Box X may ſlide,
the Box, like thoſe which are on the 117. of the Machine; in which a Ruler going ſeveral
Inches out behind the Box X may ſlide,