One of the best books we have seen on actual operation of the sextant. The author presents all of the checks and adjustments a sextant could need, and backs it all up with actual photos. He also shows photos of actual sightings with the sextant under various conditions, which clarifies otherwise abstract verbal descriptions. This compact, low priced book may be all you will need to learn celestial navigation, but if you need to turn to a more comprehensive treatment, the photos here will still be worth the price. Uses HO-229. SC,1987,110 pages SW 0.4 lbs