Al-Biruni first subdivided the
hour sexagesimally into minutes,
seconds, thirds and fourths in 1000 CE while discussing Jewish months. Historically, the word "minute" comes from the Latin
pars minuta prima, meaning "first small part". This division of the hour can be further refined with a "second small part" (Latin:
pars minuta secunda), and this is where the word "second" comes from. For even further refinement, the term "third" ( of a second) was once used, but most modern usage subdivides seconds by using decimals. The symbol notation of the prime for minutes and double prime for seconds can be seen as indicating the first and second cut of the hour (similar to how the foot is the first cut of the
yard or perhaps
chain, with inches as the second cut). In 1267, the medieval scientist
Roger Bacon, writing in Latin, defined the division of time between
full moons as a number of hours, minutes, seconds, thirds, and fourths (
horae,
minuta,
secunda,
tertia, and
quarta) after noon on specified calendar dates. Jost Bürgi was the first clock maker to include a minute hand on clock for astronomer Tycho Brahe in 1577. The introduction of the minute hand into watches was possible only after the invention of the
hairspring by
Thomas Tompion, an English watchmaker, in 1675. ==See also==