DOI Page / Citation link:
https://doi.org/10.11588/diglit.19574#0216
20O
D I A
This Dial, drawn on any tranfparent matter, as glafs, horn, or
oiled paper, {hall, on the other fide the tranfparent matter, be^
come a fouth declining weft, ftile and all, but then the I o clock
hour line muft be marked II; the XII XII; the XI o'clock hour
hour line I; XII; IX III, &c.
If you project it anew, you muft cefcribe the quadrant M W,
on the other fide the meridian line, on the center A, from M to
E, and then count, as before, the declination, altitude of the
poles, fubftile and ftile in the quadrant, beginning at M towards
E, and work in all refpects as in the fouth declining eaft ; only
number this fouth declining weft, as in the foregoing paragraph.
If you project a north declining eaft, you muft defcribe the
quadrant above the horizontal line, from M upwards towards E
on your right hand, and count, as before, the declination, alti-
tude, complement of pole, fubftile and ftile from the meridian
line, and work as with the fouth declining eaft; it muft be num-
bered from the meridian line M, towards the right hand, with
XI, X, IX, VIII, &c.
If this Dial were drawn on a tranfparent matter, the other
fide would fhew a north declining weft ; but, if you will project
it anew, you muft defcribe the quadrant above the horizontal
line, from M upwards towards W, and count, from the meridi-
an line A M, the declination, complement, altitude of the pole,
fubftile and ftile, and work with them, in all refpects, as with the
fouth declining eaft ; but then the XI o'clock hour line muft be
marked I; the X Hj the IX III, &c.
To make a Dial on the deling of a room, where the dire Si beams
of the jun never come. Find fome convenient place, in the tran-
fum of window, to place a fmall round piece of looking-glafs, a-
bout the bignefs of a groat, or lefs, fo as it may lie exactly hori-
zontal.
The point in the middle of this glafs we will mark A, and, for
diftindtion fake, will call it nodus. See plate V, fig. 3.
Through this nodus you muft draw a meridian line on the
floor, thus: Hang a plumb line in the window, exactly over the
nodus, and the fhadow that the plumb-line cafts on the floor,
at noon, will be a meridian line; or you may find a meridi-
an line other wife by the clinatory.
Having drawn the meridian line on the floor, find a meridian
line on the ceiling, thus : Hold a plumb-line to the ceiling, over
that end of the meridian line next the window; if the plummet
hang not exactly on the meridian line on the floor, remove your
hand on the ceiling one way or other, as you fee caufe, till it do
hang quietly juft over it; and, at the point where the plumb-line
touches the ceiling, make a mark, as at B ; that mark B (hall be
directly over the meridian line on the floor. Then remove your
plumb -
D I A
This Dial, drawn on any tranfparent matter, as glafs, horn, or
oiled paper, {hall, on the other fide the tranfparent matter, be^
come a fouth declining weft, ftile and all, but then the I o clock
hour line muft be marked II; the XII XII; the XI o'clock hour
hour line I; XII; IX III, &c.
If you project it anew, you muft cefcribe the quadrant M W,
on the other fide the meridian line, on the center A, from M to
E, and then count, as before, the declination, altitude of the
poles, fubftile and ftile in the quadrant, beginning at M towards
E, and work in all refpects as in the fouth declining eaft ; only
number this fouth declining weft, as in the foregoing paragraph.
If you project a north declining eaft, you muft defcribe the
quadrant above the horizontal line, from M upwards towards E
on your right hand, and count, as before, the declination, alti-
tude, complement of pole, fubftile and ftile from the meridian
line, and work as with the fouth declining eaft; it muft be num-
bered from the meridian line M, towards the right hand, with
XI, X, IX, VIII, &c.
If this Dial were drawn on a tranfparent matter, the other
fide would fhew a north declining weft ; but, if you will project
it anew, you muft defcribe the quadrant above the horizontal
line, from M upwards towards W, and count, from the meridi-
an line A M, the declination, complement, altitude of the pole,
fubftile and ftile, and work with them, in all refpects, as with the
fouth declining eaft ; but then the XI o'clock hour line muft be
marked I; the X Hj the IX III, &c.
To make a Dial on the deling of a room, where the dire Si beams
of the jun never come. Find fome convenient place, in the tran-
fum of window, to place a fmall round piece of looking-glafs, a-
bout the bignefs of a groat, or lefs, fo as it may lie exactly hori-
zontal.
The point in the middle of this glafs we will mark A, and, for
diftindtion fake, will call it nodus. See plate V, fig. 3.
Through this nodus you muft draw a meridian line on the
floor, thus: Hang a plumb line in the window, exactly over the
nodus, and the fhadow that the plumb-line cafts on the floor,
at noon, will be a meridian line; or you may find a meridi-
an line other wife by the clinatory.
Having drawn the meridian line on the floor, find a meridian
line on the ceiling, thus : Hold a plumb-line to the ceiling, over
that end of the meridian line next the window; if the plummet
hang not exactly on the meridian line on the floor, remove your
hand on the ceiling one way or other, as you fee caufe, till it do
hang quietly juft over it; and, at the point where the plumb-line
touches the ceiling, make a mark, as at B ; that mark B (hall be
directly over the meridian line on the floor. Then remove your
plumb -