How to measure longitude with a watch: a simple method that will save you

(ORDO NEWS) — In some situations, it becomes vital to determine your coordinates in order, for example, to report them by radio. Here’s how to do it with the watch.

Imagine that you are on a desert island and you urgently need to determine your location. Here’s How to Find Longitude Easily Using Your Clock and Radio

If you get lost in the forest, you are carried away by the current from the shore, or you are shipwrecked and find yourself on a desert island, do not panic and despair. If you have a watch and a radio handy, you can easily determine the geographic longitude.

Let’s imagine that you are on a desert island and the ship’s radio still survives and can work. Then you already have the first tool for determining longitude. Now you need to create some kind of clock. These would be a pendulum of a certain known length, which, as we know, will swing at a fixed frequency determined by this length.

The earth completes one full rotation (360° of longitude) in one day. Therefore, it rotates one degree of longitude in 1/360th of a day, or every four minutes. Therefore, to calculate your longitude, you simply need to calculate the time difference between noon at your location and noon at the prime meridian.

To do this, you first need to find a radio station that broadcasts GMT. Then you need to create a device for determining noon – take a pole 0.5-1 meter long and place it vertically, and then measure the moment in time when the shadow cast by it will be minimal. This will be noon. You will need to measure the time difference between local noon and 12 noon on the prime meridian.

If noon comes before the radio signal, then you are east of the Prime Meridian, and if after, then you are west. Every four minutes of difference between noons corresponds to an increase in longitude by 1 °. For example, if 20 minutes elapsed from your noon to the announcement of 12 noon GMT, then you are at 5° East longitude.


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