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Nocturnal Geocoin Bronze
This is a functional nocturnal coin which you can actually use to tell the time during the night and get your latitudinal deviation.
The early nocturnals were made of wood and later made in brass. They were approximately 7" to 10" in diameter plus the length of the handle and arm. The large circle, that has the handle attached to it, lists the days and months.
The Nocturnal Geocoin™ is trackable on Geocaching.com and has its own icon.
Shipment as package.
How to use it:
1. You will have to wait until it is night time. I know you are eager to put this coin into use, but trust me when I say it is worth the wait.
2. Determine which of the dipper constellations you will use to take your reading.
3. Then choose the corresponding tab on the time disk and align it with the current date.
4. Keep the time disk side of the coin facing towards you and hold the coin upright so that the top point of the coin is directly up and the bottom indention is centered directly down. A more accurate reading will be achieved if you ensure to do this. There are several ways to hold this coin; however, one way we found to be very effective is to place your middle finger on the top point, and place your thumb on the bottom indention. This automatically causes your hand to naturally center the top and bottom of coin vertically. Then by placing your index finger over both the time disk and the edge of the arm will prevent the pieces from moving out of adjustment once you have the moving pieces set.
5. Hold the hole of the coin close to your eye and center Polaris in it. It is more effective to keep both eyes open.
6. Then move the coin a few inches straight out from your eye while keeping Polaris centered in the hole.
7. Once you find the correct distance from your eye, align the un-notched edge of the arm with the corresponding stars in the dipper you had previously chosen (Kochab in the Litter Dipper, the pointer stars in the Big Dipper, and Shedir in Cassiopeia).
This example shows lining up the arm with the star Kochab in the Ursa Minor constellation:
This example shows lining up the arm with the star Shedir in the Cassiopeia constellation:
8. Once set, ensure the time disk and arm do not move.
9. Pull the coin away from your face and take a reading from the time ring. You now have the approximate time of night. The two examples below show the time readings from the example settings displayed above. The first picture is the time reading from the Little Dipper example, and the second picture shows the time reading from the Cassiopeia example:
10. If you know the time of your port of departure, then you can use the time reading to ensure you are keeping within the same longitude. Once you get too far to the east or west of your departure point, then the longitude calculations become inaccurate. As opposed to the nocturnal, the chronometer is the device which allowed accurate longitude readings at any point on earth.
11. The back of the coin is used to calculate latitude deviation and is scaled in minutes. You take readings with it in the same way as the time side of the nocturnal: hold the nocturnal so that the deviation scale is facing you; rotate the arm to one of the dipper constellations; then subtract or add the corresponding number which the arm references to from the latitude reading you took with your quadrant. For example: if your quadrant reads 35 degrees and the deviation of the nocturnal reads -23, then your latitude is approximately 34 degrees and 37 minutes.
|Size||from 45 mm|