History of Navigation

Title Page, The New Practical Navigator

John Hamilton Moore published this epitome of navigation for a number of years, with the eleventh edition in 1795. He particularly provided instruction for solving lunar distances. Nathaniel Bowditch found many errors in his work, and, after working for Moore to correct errors, published his own New American Practical Navigator, with improvements in the solving of lunar distances.

Title Page of William Bourne's Regiment for the Sea

The first English treatise on navigation was a translation of Spaniard Martín Cortés de Albacar's Arte de Navegar, in 1561. William Bourne revised and added to it with his 1574 Regiment for the Sea, writing explicitly for the seafarers who were his neighbors in Gravesend. The book went through at least 11 English and three Dutch editions.


This sextant was owned by Frederick L. Waterhouse. Frederick was born in Searsport in 1841; his four brothers all became ship captains, but he only became a mate. After his service in the Civil War, he settled in Montville, Maine, never becoming a sea captain. His initials are inlaid into the cover of the sextant box, something he could well have done, a not uncommon practice amongst ship officers.

Replica Nocturnal

This replica of a nocturnal was made by a craftsman in Massachusetts. The nocturnal is used to tell the local time at night. When dials are set for the date, one index arm is lined up with the pointer stars in either Ursa Major or Ursa Minor and the other directly towards the zenith. The time can then be read off the dials. These instruments were used in the 17th century and 18th centuries, in an era where portable watches were too expensive for mariners.

Recognition Views along Maine Coast

These recognition views of Mount Desert and other places along Maine's coast help navigators determine their location. These are from The English Pilot, Fourth Book, published in 1767. Online via Boston Public Library.

Parallel Rules

The parallel rules are used to plot courses, bearings, and celestial lines of position. By “walking” the rules across the chart, the navigator transfers the desired angle from the compass rose on the chart to the part of the chart where the ship is, or vice versa. A pair of triangles can do the same thing, while course plotters are designed to minimize effort in laying out angles.

Navigation Electronics aboard Trawler Robert F. O'Hara

Navigation electronics aboard the 109-foot steel side trawler Robert F. O'Hara, built at the Harvey Gamage yard in South Bristol, Maine in 1971.

Lead Line, Chip Log, Walker Log, Compass, and Speaking Tubes

This diagram shows important tools of the navigator for dead reckoning and piloting, including the lead line, chip log, a mechanical log, and a compass. For communications, speaking tubes are shown on the left. This illustration is from H. Paasch's Illustrated Marine Encyclopedia, 1890, Plate 98. For a 17th century navigator only the mechanical log would have been new.

Isosceles Triangles

Triangles provide a simple and inexpensive alternative to the parallel rule for transferring a bearing or course from the compass rose to the ship’s position on a chart. These triangles are made of wood.

Gulf of Maine Chart, 1853

The Gulf of Maine is shown in this part of a much larger chart, Gulf and River St. Lawrence, including the Coast from Breton Island to Cape Cod and the Island & Banks of Newfoundland. The chart was published by the well-known chart maker James Imray of London in 1853. By today's standards these charts have nowhere near the detail that we are accustomed to on our harbor and near coast charts, but they did serve to plan voyages and plot positions of the ship at sea.


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