Davis Quick Reference Celestial Navigation Card 
Quick Reference Celestial Navigation Card
A simplified, yet complete Celestial Navigation system. Includes everything you need: sextant use and corrections, star finder for 18 stars, data entry form, and step-by-step sight reduction and plotting procedures. May be scored and separated; a large portion fits in the sextant case for quick reference, and a small part acts as a waterproof data reduction card.