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History of navigation stored in Osher Map Library

First published in Landings November, 2022

Fishermen need to know where they are when they are on the water. For some older fishermen, that knowledge is hardwired into them by years of attention using a compass and a watch. Others today may depend on a GPS unit, electronic plotter and other devices. For centuries, mariners relied on charts to give them a sense of their location. Some of those earlier charts provided an imaginative view of the world, often featuring sea serpents and dragons among the known lands.

The Osher Map Library and Smith Center for Cartographic Education on the University of Southern Maine’s Portland campus contains a wealth of ancient and modern maps and charts highlighting the evolution of the cartographic art. Louis Miller is the Cartographic, Reference and Teaching librarian at the Library. “Maps and charts capture people’s attention. There’s something about them universally accessible to everyone,” he said.

Eleanor Houston Smith donated her collection of maps, atlases, and globes to the University in 1986, in memory of her late husband Lawrence M. C. Smith. Dr. Harold Osher and his wife Peggy Osher donated their extensive map collection to the University in 1989 as well as additional resources for the creation of a special map library. The physical facility opened in 1994. Since that time, other donations have increased the size and scope of the collections. The growth of its collections led to expansion of the library in 2009 and purchase of sophisticated digitization equipment to begin digitizing materials.

The Library currently holds half a million maps that date back to 1475. The materials are available not only to USM students but to the general public as well. More than 80,000 materials have been digitized for use online.

Rhumb lines and knowing the coast were keys to successful navigation in the 1500s. Photos courtesy of Osher Library.

Among the highlights of the Library is a 1583 chart called the Portolan chart of the Mediterranean Region. Portolan charts are characterized by a network of rhumb lines leading from the circles, concentrate on the coasts and islands, and have place names written perpendicular to the coastline on the land side. Hand drawn on vellum, this historic Mediterranean chart also has drawings of castles and flags from around the region and a flock of mythical creatures, including a unicorn, along its edges.

“It is a practical chart used for navigation,” said Miller, “but it also shows how someone visualized the world. It has a water stain. It shows that it was used on a voyage.”

At that time, sailors navigated via rhumb lines. Mariners paid great attention to such things as wave and cloud patterns or the presence of certain birds to estimate where they were relative to the coast. As cartography progressed, the degree of detail in charts increased as well. Mythical creatures disappeared as chart makers brought more scientific methods to bear. The Library’s J.W. Des Barres charts from the late 1700s are precise illustrations of the islands and water depths along the coast of Maine. A 1776 chart of the islands of Casco Bay, for example, gives soundings throughout the Bay and shows the islands’ extensive tidal flats, even roads and houses along the shore.

A 1740 chart by John Senex of the coast from Staten Island to Cape Breton in Canada highlights the large and small fishing banks within the Gulf of Maine. Some are called simply “pollock bank” or “cod bank.” Senex also identified dangerous rocks and shoals with notes such as “Ledg of rocks shewn at ½ Tyde” or simply “Dangerous Rock.”

John Senex's 1740 chart shows fishing grounds from new York to Cape Breton.

“There was beauty in the maps of the 16th century through the 19th century,” Miller said. “In the 20th there was a switch from art to science, to data.”

Miller is particularly fond of charts because they often come with annotations. A captain may have marked the chart with a comment about weather, or a whale caught, or other items of interest. “You get a sense of how it was used,” Miller said. The charts also give a sense of the non-static nature of the ocean. With each season, the patterns of wind and current change, facts that careful cartographers would include on their charts.

The Library, while a repository of centuries of extraordinarily valuable maps and other materials, makes its collections open and accessible to the public, through exhibits within the Library and with other institutions, through dozens of classes for students, and through its growing digital offerings.

"The Library is much more welcoming than most other institutions. Education really is at the core of our mission,” Miller said. “You can visit from Tuesday to Friday from 10 to 4 or by appointment. And anyone can contact me if they want to see something in particular.”


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