More on Astronomical Measurement from Infoplease:

• John Dollond - Dollond, John Dollond, John , 1706–61, English optician and inventor. A silk weaver, he ...
• Health and Science - Facts on weather, space, astronomy, explorations, inventions, aviation, health, science, computers, and the Internet.
• Health and Science - Facts on weather, space, astronomy, explorations, inventions, aviation, health, science, computers, and the Internet.
• Conversion Calculator - Interactive metric conversion calculator used to convert between various units of measurement. Area, volume, length/distance, cooking, time, and more.
• day - day day, period of time for the earth to rotate once on its axis. The ordinary day, or solar day, ...