ITALIAN LINES
BABYLONIAN LINES
UNEQUAL, BIBLICAL, and TEMPORARY HOURS
BABYLONIAN LINES
UNEQUAL, BIBLICAL, and TEMPORARY HOURS
Italian lines are simplicity themselves.
They show the number of hours since the last sunset, however their practical use is in reality the number of
hours until the next sunset. They complement Babylonian hour lines which deal with sunrise.
Italian lines are latitude specific and thus cannot be corrected for latitude using the usual tricks.
Here is an example of a vertical decliner dial built empirically, but with Italian hour lines added using the
standard method. This is specific to the latitude of Silver City, NM USA.
And here is an example of several dials using Italian lines,
and it includes a table which is also in the appendices book
here.
The method of drafting Italian hour lines is simplicity itself.
1. Identify sunset for the winter solstice (vertical) or summer
solstice (horizontal). Ditto for the equinox. IGNORE EOT
2. Mark one hour before that for the solstice and equinox
3. Draw a line and extend towards the other solstice.
4. Mark that line as 1 hour to sunset.
5. Repeat for 2, 3, 4 etc hours before sunset.
They show the number of hours since the last sunset, however their practical use is in reality the number of
hours until the next sunset. They complement Babylonian hour lines which deal with sunrise.
Italian lines are latitude specific and thus cannot be corrected for latitude using the usual tricks.
Here is an example of a vertical decliner dial built empirically, but with Italian hour lines added using the
standard method. This is specific to the latitude of Silver City, NM USA.
And here is an example of several dials using Italian lines,
and it includes a table which is also in the appendices book
here.
The method of drafting Italian hour lines is simplicity itself.
1. Identify sunset for the winter solstice (vertical) or summer
solstice (horizontal). Ditto for the equinox. IGNORE EOT
2. Mark one hour before that for the solstice and equinox
3. Draw a line and extend towards the other solstice.
4. Mark that line as 1 hour to sunset.
5. Repeat for 2, 3, 4 etc hours before sunset.
December 21, 2010
For other dial furniture, look at the declination or calendar line page
For other dial furniture, look at the analemma page
NOTE: The spreadsheets
"illustrating-shadows.xls" and ".ods"
show sunrise and set for your location
with and without the EOT adjustment
in order to make this process easy.
"illustrating-shadows.xls" and ".ods"
show sunrise and set for your location
with and without the EOT adjustment
in order to make this process easy.
ITALIAN LINES
While technically the Italian hour day
starts at sunset, their best use is to
show hours until sunset.
BABYLONIAN LINES
The Babylonian hours start at sunrise.
The process is the same as for Italian
lines except that sunrise is used, not
sunset.
While technically the Italian hour day
starts at sunset, their best use is to
show hours until sunset.
BABYLONIAN LINES
The Babylonian hours start at sunrise.
The process is the same as for Italian
lines except that sunrise is used, not
sunset.
UNEQUAL, TEMPORARY, or BIBLICAL HOURS
The unequal hours, temporary hours, or biblical hours are simply a given day’s daylight
(see above) divided into 12 equal parts. Those parts vary from day to day, shorter in
winter, longer in summer, one hour during the equinoxes. They are drawn by deriving
the length of day at the winter solstice (for vertical dials) or summer solstice (for
horizontal dials), dividing that duration by 12, and marking those times from noon on the
solstice curve. At the equinox mark the times in 1 hour increments from noon. Connect
the two points for each of the 12 “parts” and extend the lines. The result is a set of
“hour” lines indicated by the nodus. Not much use these days, but of historical interest,
and as such they can be found on some European dials.
The unequal hours, temporary hours, or biblical hours are simply a given day’s daylight
(see above) divided into 12 equal parts. Those parts vary from day to day, shorter in
winter, longer in summer, one hour during the equinoxes. They are drawn by deriving
the length of day at the winter solstice (for vertical dials) or summer solstice (for
horizontal dials), dividing that duration by 12, and marking those times from noon on the
solstice curve. At the equinox mark the times in 1 hour increments from noon. Connect
the two points for each of the 12 “parts” and extend the lines. The result is a set of
“hour” lines indicated by the nodus. Not much use these days, but of historical interest,
and as such they can be found on some European dials.