Greek

Construction of the polometer

Materials

One piace of wood, thick cardboard or felizol, dimensions 25 cm´15 cm. A piece of packthread . A blade.

Construction

1st step: in the middle of one of the narrow side, using the blade we create a semicircular opening 2 cm in diameter.

2nd step: 8 cm below the opening, we make a small hole, where we attach the packthread by making a knot. The polometer is now steady.

Guidelines of use

In a cloudless night stand in the open air, so that the horizon line is visible. Scan the sky and detect Ursa Minor and Ursa Major, as it is shown in Fig. 1. Find the bright star of the constellation, by following the tail of Ursa Minor. It must be noted, that Ursa Minor and Ursa Major are visible throughout the year.

Hold the polometer with your left hand, so that the opening looks to the sky. The lower narrow side should touch the horizon, in order to see the polar star through the opening of the upper side. Holding it steadily, pull the packthread with your right hand. Stretch out the packthread till it touches the tip of the observer’s nose. At this end of the packthread carefully make a knot. Remove some steps and repeat the above procedure. You will notice, that the knot’s position is different (does not touch the nose anymore).

Following the above procedure, a sailor could measure any change of the ship’s route.

Ursa Minor and Ursa Major

At the 4th century A.D. a wise man suggested that the Greeks should named the stars after famous heroes in order to be easily recognized and understood. The nameless stars had been bringing confusion to the scholars of that time. Hence, the Greeks created groups of stars, the constellations, according to their myths.

Connecting the stars with imaginative lines, they were able to create in their mind a certain shape. For example, the shape of the constellation of Argo reminds us of the bow of a ship. This constellation was attributed to the mythical ship of Argo. Hence, this kind of star nomenclature familiarized the people with the stars. The peasants, the hunters, the shepherd and the sailors could find easily their way, either in the land or in the sea. They could also determine the hours during the night, the season of plowing and sowing. For example they could find immediately the north direction by watching the Polar Star.

Although the Greeks were not the first people who named and classified the stars into constellations, since they borrowed knowledge from the nations of the East, they transformed and adapted this knowledge to their own spirit. That’s why they preferred to use their own myths about each constellation.

Two of the well known constellations are Ursa Minor and Ursa Major. According to the Greek mythology Eliki and Kynosoura, nymphs from Crete, hid and took care of Zeus in a cave, when he was a baby. They wanted to protect him from Kronos who used to eat all his children. When Zeus came in power, expressed his gratitude by making them stars.

Another story for the same constellation claims that nymph Callisto, priestess of Artemis, betrayed the oath to Artemis to stay for ever a virgin, when Zeus fell in love with her, giving birth to a child named Arcadas. Artemis got mad with her and transformed her to a bear. When her son saw her, he started to hunt her, thinking she was a real bear. Zeus fell sorry for them and transformed them, mother and son, into stars. Hence, Ursa Major (Callisto), and Ursa Minor (Vootis, the Arcas) have been born. Ever since, these constellations help travelers and sailors, whereas, in the past, the use of polometer was based on them.

Bibliography and Iconography

• Christos D. Lazos, Nautical Technology in Ancient Greece, Aiolos, Athens1996
• Greek Mythology, Ekdotiki Athinon
• Stella Vlahopoulou, Myths and Stars - Diary 2006, Kedros
• Ath. Gialouri, Myths of Ancient Greeks for constellations, Delphini
• Arktos, a protection project of the brown bear and its biotope 1995

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