The Lunarian or Seaman's Guide, written by E. Ward and published in 1817, is a practical guide for seafarers to ascertain the longitude at sea through celestial observations. The book provides a comprehensive introduction to the methods used to measure the position of the stars and the moon in relation to the horizon and the meridian. The author explains the use of various instruments such as the sextant, chronometer, and nautical almanac, and provides...