Astronomical Clock, or "Volvelle"

Brief history of the telescope and how it works

      Astronomical Clock- "By this Instrument you may tell, at any Time, by Day or by Night, the Situation of those Stars when they are not visible, by Reason of the Sun's superior Light, or Clouds: For, having set the Day of the Month to the Hour, by your Watch, hold up the Book with its Back towards the North, and then the Stars upon the Clock will correspond with those in the Heavens, and point their Places there." This instrument has two parts: one fixed and one moveable. The fixed part is divided into the twenty-four hours of the day, and the moveable circle consists of stars and constellations that are bounded with the twelve months. To use this device, hold the back of the clock towards the North Pole, then move the inner cirlce around until their situation looks the same as to how they are in the heavens. On the fixed circle it will show the day of the month along with the hour of the night [1].