Galileo's Instruments of Discovery With these various
instruments, Galileo Galilei was able to look into space and
change our view of the universe. - By Sarah Zielinski -
Smithsonian.com, July 20, 2009 At night, this small device could
be used as a nocturnal to tell time. During the day, it could be
used as an horary disk to tell time and also to determine when
the sun and moon would rise and set. Similar devices went into
use in Europe around the eighth century. This one dates to 1647.