Capuchin Dial
Uhrentäfelchen
| This
instrument
is a portable sundial for a single latitude, developed by Regiomontanus
(1436-1476). It also indicates the time of
sunrise and sunset. It is equipped with a simple Sun sight on the upper edge. A thread with a sliding bead is hanging from a movable point of suspension within the date scale. |
See
instructions for interactive use below
Quadratum Horarium
Generale (Regiomontanus Dial)
 |
Enter the year into text field and hit Return key. (Gregorian Calendar only, later than 1582) |
  |
Enter the latitude (decimal degrees) into the
text field and hit Return key. The latitude is indicated in the text field. |
 |
The interactive
regions (light gray scales) are changing the cursor to cross hair. |
 |
Click into the
degree scale (light gray) on the lower and left limb to direct the
quadrant to the Sun. The thread will follow the elevation angle. |
 |
Use the
"Today"
button to set the thread to the current date. The bead is set to the noon
point
automatically. |
 |
- Click into
the light gray
calendar (date scale, upper part for
winter and spring, or lower
part for summer and autumn) to set the thread to the date. - To bead is set to the noon point automatically. |
 |
Read the date,
the declination, and the time of sunrise and sunset (neglecting
refraction on the horizon), the equation of time, the current time, and
elevation as computed by
astronomical algorithms. |
| Select from the
"Display Options" menu. |
|
| The red frame
of the applet area is a square (753 x 753 pix, same size as for
the Quadratum Horarium Generale and for Gunter's quadrant). |
|
| The dial is
obeying the equation of the nautic spherical triangle (h = elevation
angle, φ = latitude,
AH = hour angle):
sin h = sin φ
sin δ + cos φ cos δ cos AH
|
Under
construction!
| Books |
| Rohr, René R. J.: Die
Sonnenuhr. Geschichte, Theorie, Funktion. Callwey, München 1982. Meyer, Jörg: Die Sonnenuhr und ihre Theorie. Harry Deutsch, Frankfurt 2008. |
|
|
|
Regiomontanus,
Apian and Capuchin Sundials Das
Allgemeine
Uhrentäfelchen
von
Regiomontan Tragbare
Sonnenuhren in Europa ab 1400 Uhrentäfelchen von P. Aegid Everard Pourquoi le cadran de Regiompntanus fonctionne-t-il ? Horoscopion
Apiani Generale Dignoscendis Horis cuiuscumque generis aptissimum Quadratum
Horarium Generale Georgius Hartman |
©
2009-2010 J. Giesen
