ID: Secanda 16.7 (2016-12-14)
Version: 1a (2016-12-14)
Format of the plates to print: A4
Number of plates to print: 13
Including a notice: Yes
File: secanda_16_7_v_1_a_cadran.pdf (5 580 Kb)
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Last downloading at: 2023-12-09 14:03:32
There are many types of sundials. This is the type called "equatorial" that is to say that the plan of the dial is parallel to the equatorial plane and its axis is parallel to the axis of rotation of the Earth. It is thus a kind of flat model of the Earth.
# The advantages of the equatorial sundial:
- It is universal: it works all around the world without further changes than the orientation and the inclination of its disk.
- It is easy to read because the hours are regularly distributed around the disc (at an angle of 15 ° per hour)
- It is very easy to adjust; you only have to know the latitude and the meridian.
- Correcting the solar time in standard time is very easy: a simple partial rotation of the disk.
# The disadvantages of the equatorial sundial:
- The disc must be scaled and visible on both sides.
- For six months of the year (short days) reading is on the underside of the dial, which is few readable at high latitudes (Arctic and Antarctic).
# How to use the equatorial sundial:
- Tilt the disk the value of the latitude (scale on the side holders).
- Point the top side to the north (in the northern hemisphere) or south (in the southern hemisphere). The red line on the base must be aligned to the local meridian.
- While aligning the bottom mark with "XII", you get the true local solar time. For getting the legal time, rotate the disk the number of hours necessary +/- the longitude correction +/- the equation of time.
License: common law (copyright) | Author: Secanda
Free use for private purposes. Any commercial use is prohibited.