The telescope is an intriguing and classic explorers and navigators tool. Essential instruments: a compass, a sextant and a telescope. The telescope consists of a wood barrel holding an objective, a system of lenses. It is protected by brass collars and a decorative brass cap.
To use the telescope, pull out the brass tubes (called drawers in Britain); the smallest tube holds the eye objective. Judiciously push in the smallest end-tube to focus. 4x magnification.