A laboratory diary of Yrjö Väisälä. The text is written in 1929. On the pages seen here Väisälä describes the principle of 'a new telescope for photography'. Väisälä never published this concept and a few years later the Estonian Bernhard Schmidt invented the same construction, which is now known as the Schmidt camera.
An early 20th century wooden house in Joensuu at the corner of Sepänkatu and Papinkatu streets. The building was Väisälä brothers' home in 1904–19.
Esperanto
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Esperanto is the world's most widely spoken constructed auxiliary language. Created by L. L. Zamenhof in 1887 as 'the International Language', it is intended to be a universal second language for inte
Yrjö Väisälä
…Vilho Väisälä (1889–1969). His daughter Marja Väisälä (1916–2011) was an astronomer and discoverer of minor planets. Väisälä was a fervent supporter of Esperanto, presiding over the Internacia Scienca Asocio Esperantista ("International Association of Esperanto Scientists") in 1968. He developed several methods…
Zamenhof, c. 1895
7th Esperanto congress, Antwerp, August 1911
The Republic of Rose Island in the Adriatic Sea used Esperanto as its official language in 1968; it has since been demolished
Esperanto books at the World Esperanto Congress, Rotterdam 2008