Celestial Navigation is one of the oldest human pursuits. So old that more ways to navigate have been forgotten then are now remembered. There have been many different methods for using the sky to navigate. No single method for navigating is perfect, each idea or device has merit. The devices that we lable antique are only antique in that we have more modern means of finding where we are. In our modern world we have technology that gives us almost instant comunication with satelites and computers that do the math for us. These techology based celestial navigation devises have distanced us from the act of navigation itself.
The Sun rises in the east and sets in the west, but you can also use sun charts with the length of a shadow at noon to measure latitude. Clouds have been used by mariners to find land. These Clouds form over land so a captain of a ship sighting a cloud high in the sky can follow it to the land underneath. Birds have thier own methods for navigating and can be followed to find land.
The Polar Star is .68 degree away from true north and can be found using the two stars that form the end of the cup of the big dipper. You can use the North or Polar star from anywhere in the entire northern hemisphere to find north. Seamen took this simple way of finding north one step farther. They measured the distance of the star above the horizon by using their fingers to gadge the height of the Polar star. The closer to the north pole the higher in the sky the Polar star would be.
The Astrolabe is an antique nautical device that refinded the process of measuring the height of the sun or the stars. There were many different inovations for the astrolabe, but the all were circular with degrees marked off along the edge. The astrolabe was sited through to find the celestial body. In the case of the sun a ray of light could be focused through holes to fall on the the astrolabe giving a more precise angle of the sun's height.
Sextants are another antique nautical device used to find latitude on the open ocean. They are called sextants because they can measure 60 degrees of a full circle. The sextant can be used with any celestial body. Most often it is used with the sun or stars. Simply put all you have to do is sight the instrument with the sun or star and then line up the star with the horizon using the mirrors that make up the sextant. Many sailors have elevated the science of navigation using sextants to an art form. The office of navigator was a full time job on many ships.
So far we have only talked about how to measure latitude. An easy and accurate way of finding longitude took many centuries to develope. Originally ships would sail to the correct lattitude and the turn to starboard or port and sail east or west until they reached the port they were sailing for. The Chronometer was developed early in the 18th century that was accurate enough to keep time over long voyages. The chronometer was set to the time of a home port. Out on the ocean a Ship's navigator or Captian would find the time of his position at noon and then use the diference between this time and the time of the chronometer to give him an acurate distance from his home port. Over time this home port became standardized to Greenwhich.