1859 Purdy / Vidal Chart of the Azores, Portugal

An impressive 1859 blueback chart of the Azores and surrounding waters, drawn by Isaac Purdy, based on surveys by Captain A.T.E. Vidal, and published by Richard H. Laurie.

A Closer Look

The islands of the Azores are covered in their entirety, with elevation and other topographic details illustrated and elevation noted at peaks. Along their coasts, soundings, hazards, shoals, and other features are indicated, along with some outcroppings further afield, including a volcano and 'Whale Rock' just below the title. Compass roses with magnetic variations and a text block discussing winds at top-left further assist the navigator. Three inset maps appear at bottom-left, detailing the channel between Fayal and Pico, the Road of Angra, the capital and largest city on the island of Terceira, and S. Miguel or St. Michael, the largest of the eastern Azores. Eleven profile views surround the chart, the location from which they were drawn being recorded on the chart.

A note below the title refers to directions which can be found in the North Atlantic Memoir (Memoir, descriptive and explanatory, of the northern Atlantic Ocean). Although by this time the Azores were no longer a colonial testing ground for Portugal, they retained their importance for navigation and as a stopping point in the North Atlantic for transatlantic voyages. As an indication of their continued significance, during World War II (1939 - 1945) the Allies contemplated seizing the island chain from neutral Portugal to use its airfields to protect Allied convoys being harassed by German U-boats. However, Portugal agreed to let the Allies use the airfields and an occupation was unnecessary.

Blueback Charts

Blueback nautical charts began appearing in London in the late 18th century. Bluebacks, as they came to be called, were privately published large format nautical charts known for their distinctive blue paper backing. The backing, a commonly available blue manila paper traditionally used by publishers to wrap unbound pamphlets, was adopted as a practical way to reinforce the low-quality paper used by private chart publishers in an effort to cut costs. That being said, not all blueback charts are literally backed with blue paper. The earliest known blueback charts include a 1760 chart issued by Mount and Page, and a 1787 chart issued by Robert Sayer.

The tradition took off in the early 19th century, when British publishers like John Hamilton Moore, Robert Blachford, James Imray, William Heather, John William Norie, Charles Wilson, David Steel, R. H. Laurie, and John Hobbs, among others, rose to dominate the chart trade. Bluebacks became so popular that the convention was embraced by chartmakers outside of England, including Americans Edmund March Blunt and George Eldridge, as well as Scandinavian, French, German, Russian, and Spanish chartmakers. Blueback charts remained popular until the late 19th century, when government subsidized organizations like the British Admiralty Hydrographic Office and the United States Coast Survey began issuing their own superior charts on high quality paper that did not require reinforcement.

Publication History and Census

This nautical chart was drawn by Isaac Purdy based on surveys by A.T.E. Vidal and published by Richard Laurie in 1859. It is not listed in the OCLC and its only known institutional holding is with the Museu Marítim de Barcelona.