These two sundials are on the main door of the Sanctuary of Black Madonna in Jasna Góra in Czestochowa.
Location: Jasna Góra (map)
This fountain representing the Solar System was totally renovated and redesigned as a part of the Old Town of Torun renovation in 2008. It gushes water out of 115 nozzles in the perimeters of the orbits of the planets up to the height of 5 meters.
Location: Fontanna Cosmopolis in Torun (map)
Only five seconds to remember this other monument dedicated to Nicolaus Copernicus and his heliocentric system in Torun!
Cahit Arf (Selanik, 11 October 1910- Bebek, 26 December 1997) was a Turkish mathematician known for the Arf invariant of a quadratic form on characteristic 2.
I didn’t know who was this man until I saw him in the new 10 Turkish lires note:
He probably is the most important Turkish mathematician and the doodle published in 2010 to celebrate his 100th birthday is another example of this fact. Happy birthday Cahit!
After the prize of 20.000 pounds established by the British Parliament in 1714 for someone who would find an exact method of measuring the geographical longitude of a ship on the open sea and the victory of John Harrison’s “chronometers”, the navigation across the oceans changed a lot. However, since even the most exact chronometers erred a few seconds after a long journey, a lot of sea ports decided to have a time-ball (as we saw in Greenwich!) installed on a tower or a lighthouse.
The ball’s fall at noon let the captains adjust their ship’s chronometers before the next voyage.
The Gdansk ball was the first one in the Baltic Sea and it seems to be the only openwork time-ball in the World. It was first constructed in 1876 on the top of a wooden tower which was especially built although it was transferred to the new Nowy Port lighthouse in 1894 (the current location!).
The invention ofradio by Marconi at the turn of the XIX-XX centuries spelled the end of the time-ball era. The first radio station in Gdansk went into service in 1921, and when in 1929 a heavy strom ripped the Gdansk time-ball off the top of the lighthouse, it was never repaired. First in 2008, four years after the lighthouse itself was restored and opened to the public, was the famous Time-Ball reconstructed.
I think I’m going to look for other time-balls in the World. It seems to be very interesting!
Location: The Gdansk Time-Ball in Nowy Port (map)