25/08/1609 Galileo Galilei demonstrates his first telescope
The Day Galileo Changed The Universe
Telescopes: Crash Course Astronomy #6
Galileo - Mini Biography
Galileo demonstrated one of his early telescopes, with a magnification of about 8 or 9, to Venetian lawmakers. His telescopes were also a profitable sideline for Galileo, who sold them to merchants who found them useful both at sea and as items of trade.