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.
The macros in the dial furniture zip file have sub programs for the
hDial, vDial, and pDial for DeltaCAD. Also, the DeltaCAD main dial
programs for the h, v, and p dials have the Italian line option.
|For dial furniture with Italian lines, look at this macro collection
NOTE: The spreadsheet
"illustratingShadows.xls" show sunrise
and set for your location with and
without the EOT adjustment in order
to make this process easy.
While technically the Italian hour day starts at sunset,
their best use often is to show hours until sunset.
The Babylonian hours start at sunrise. The process is
the same as for Italian lines except that sunrise is used,
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.
For other dial furniture, look at the analemma page