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George Davidson's Recreation of Martin De Aguilar's Tracks along the Coast of California and Southern Oregon in January 1603

A unique and exceptional object, illustrating the work of George Davidson, one of the great American cartographic minds of the 19th Century, attempting a scientific recreation of one of the earliest recorded Spanish Voyages on the West Coast of North America.

The base chart is a thick paper separately issued chart of the Coast of Northern California and Oregon, from San Francisco to the Winchester Bay area, just north of Coos Bay, including 12 coastal profiles, sailing directions and a host of other details.

The chart was originally created by the US Coast Survey in 1854 and periodically updated with new information.   

This example of the chart is extensively annotated by George Davidson, and was once part of his collection of maps acquired by the Bancroft Library early in the 20th Century.  "[George] Davidson was for many years connected with the United States Coast Survey and is considered the leading authority on the early explorations of the Pacific Coast." (McArthur I, page 371).  He served as President of the Geographical Society of the Pacific and published numerous papers on the history of the Pacific Coast.  "The list of early navigators who touched on the coast and whose charts and narratives [Davidson] indefatigably searched out is a long one, including Cabrillo (1542), Cermeno (1595), Vizcaino (1602) and numerous other early Spanish and Portugese explorers . . ." (Lewis, p.108). 

Davidson's Reconstruction of the January 1603 Martin de Aguilar Expedition from Monterey to Cape Blanco Using His Own Modern Scientific Methods

In the annotations on this chart, Davidson undertakes a methodical look the last portion of the Vizcaino Expedtion to California in 1602-03 and specifically that part of the expedition led by Martin De Aguilar, after Aguilar's ship became separated from Vizcaino's ship north of Monterey during a storm on January 5, 1603.  Utilizing the contemporary journals describing Aguilar's tracks along the coast from the San Francisco area to the Cape Blanco area, Davidson meticulously applies his modern observations regarding prevailing winds, ocean currents, modern topography and a reconstruction of the errors in the instrumentation available to the Spanish mariners in 1603, in order to recreate Aguilar's actual course during the month of January 1603.  His work would later become the subject of a published paper on this topic.

As noted by Davidson in the introduction to his 1886 An Examination of Some of the Early Voyages of Discovery and Exploration on the Northwest Coast of America, From 1539 to 1603 (US Coast & Geodetic Survey, Methods and Results . . . . Appendix No 7), page 150

During my work on the Pacific coast of the United States since the spring of 1850, I became deeply interested in the discoveries and explorations of the early Spanish navigators who had followed the coast from Cape San Lucas to Alaska. Part of my duty consisted in the determination of the latitude and longitude of the headlands, islands, rocks, harbors, rivers, &c., and in the geographical reconnaissance of the shores from the Mexican boundary to the forty-ninth parallel. While in command of the surveying brig R. H. Fauntleroy, I entered (in addition to my regular duties) npon the self-imposed task of writing a Coast Pilot for California, Oregon, and Washington Territory . . . . Very naturally, my early interest in the old explorations became intensified, and I made many special examinations of the narratives and their application to supposed localities. I think I have been able to reconcile many of the discrepancies of the old Spanish, English, American, and French navigators. Their inaccuracies arose principally from "constant" errors of their instruments, ignorance of the coast currents, errors of judgment in estimating distances, &c.  Among the Spanish discoverers, the meagerness of detailed descriptions, a failure to seize the salient points for the determining of their positions, the want of minute accuracy in most of their plans—sometimes giving weight to general features and sometimes to details without distinction—and a leaning to exaggerate certain discoveries and to completely overlook others, have much involved the locating of many of their landfalls, headlands, mountains, and streams. . . . I cannot withhold my admiration for the indomitable courage and perseverance of the old Spanish navigators, who, in small, ill-conditioned, and ill-supplied vessels, with crews nearly destroyed by scurvy, fought their way to the wildest parts of the Alaskan coast almost regardless of season. "There were giants in the earth in those days."

The records of such of these voyages as are published are too short to be of much more value than isolated statements of what was done; and the inaccuracy of the observations for the determination of the geographical positions has led many to judge that all were touched with the spirit of Maldonado, de Fonte, and de Fuca. But with the present knowledge of our coast it is possible to locate Ulloa; to track Cabrillo and Ferrelo in their discoveries in mid-winter; to place Drake under Cape Ferrelo and Point Reyes, and to fix with certainty the most of Vizcaino's positions. Later than 1603 I have not undertaken identification in this paper, except to incidentally mention Father Taraval's visit to Point Eugenio, and his landing upon Natividad and Cerros . . . .

Map Details

The chart provides the first modern scientific mapping of the coastline between San Francisco and the Coos Bay Oregon area.  It includes profile views include Cape Arago, Cape Blanco, Robers River, Mark's Arch and Reef, Crescent City, Red Bluff, Cape Mendocino, Trinidad Head and City, Mendocino Cove, Pt. Arena, Pt. Reys, and the Entrace to San Francisco Bay.

We note significant revisions from earlier states of the map, including:

  • San Francisco Bay and Drake's Bay added
  • Light Houses note added at the bottom of sailing directions
  • Compass Variations reoriented
  • Empire City added

Davidson Recreates The Vizcaino Expedition

'The map includes two sets of annotations, both almost certainly in the hands of George Davidson.

The first set, in pen, shows 3 the location of Cape Sebastian, Pistol River and Cape Ferrelo.

The second set, in pencil, is the extensive recreation of the track of Martin de Aguilar's ship in January 1603.

Martín de Aguilar

Martín de Aguilar (fl. 1603) was a Spanish explorer whose log contains one of the first written descriptions of the coastal regions north of San Francisco, extending to Cape Blanco and perhaps further north to Coos Bay.

Aguilar participated as a  sailor on the expedition of Sebastián Vizcaíno in the Gulf of California (June—November 1596).  Thereafter, he was an ensign aboard the frigate Tres Reyes on Vizcaíno's voyage to chart the coast of the Californias in 1602–1603.  Vizcaíno set out from Mexico in 1602 in search of usable harbors and the mythical city of Quivira.

Aguilar participated in the survey of Monterey Bay and the re-provisioning of the ship, thereafter sailing north on January 3, 1603 as commander.  While exploring along the northern California coast, a storm separated Vizcaíno and Aguilar's ships on January 5, 1603.  While Vizcaíno may have reached the present Oregon-California border, Over the course of the next several weeks, Aguilar continued up the coast. Aguilar is thought to have sighted and named Cape Blanco, and he may have sailed as far as Coos Bay. 

Aguilar reported sighting a "rapid and abundant" river that he did not enter because of the current, which many at the time believed to be the Straits of Anian.  He then turned back to Mexico because of scurvy among his crew. Both Augilar and his Pilot, Antonio Flores, died on the return voyage.  The contemporary account of the voyage was told by the boatswain upon his return to Mexico.

It is unknown what river he sighted, but his discoveries took on a mythical quality that would last for nearly 200 years.   No reported exploration of the Northwest Coast occurred again until some 150 years after Aguilar.

Cape Sebastian

The appearance of Cape Sebastian in George Davidson's hand is of great import.  In describing the history of the name Cape Ferrelo, the Oregon Historical Quarterly notes at page 188:

CAPE SEBASTIAN, Curry County. Cape Sebastian derives its name from the fact that on January 20, 1603, Sebastian Vizcaino on an exploring expedition north from Mexico sighted a high white bluff near what he determined to be the 42nd parallel. He named it in honor of the saint of that day, San Sebastian. This point marked the northern limit of his voyage, but his recorded latitudes are much too high. What cape he saw and named it is not now possible to determine with accuracy, but the name Cape Sebastian is fixed on a cape in north latitude 420 19' 40". The name was first applied to this feature by George Davidson in the U. S. Coast Survey Coast Pilot for 1869, page 112.

Cape Ferrelo

The appearance of Cape Ferrelo in George Davidson's hand is of great import.  In describing the history of the name Cape Ferrelo, the Oregon Historical Quarterly notes at page 187:

CAPE FERRELO, Curry County. Bartolome Ferrelo (Ferrer) was a  pilot in the expedition of Juan Rodriguez Cabrillo, a Portuguese, who  sailed from Mexico in June, 1542, for the purpose of exploring the coast of California. When near the 34th parallel of north latitude Cabrillo sank under the fatigue of the voyage and turned the command over to Ferrelo. The latter discovered a cape on the 41st parallel which he called Cabo de Fortunas, and on March 1, 1543, found himself to be as far north as the 44th parallel, but on the following day bad weather drove him south. It is now not easy to determine how far north Ferrelo came, nor what he actually discovered. H. R. Wagner in Cartography of the Northwest Coast of America, volume II, page 373, says that Cabo de Fortunas was probably the modern Point Arena, and apparently Ferrelo saw no more land north of that. His latitudes were considerably in error. There is nothing to connect the Cape Ferrelo with Bartolome Ferrelo the pilot, though it was named in his honor by George Davidson of the U. S. Coast Survey, probably in 1869.

A unique and exceptional object, illustrating the work of one of the great cartographic minds of the 19th Century attempting a scientific recreation of one of the earliest recorded Spanish Voyages on the West Coast of North America.

Condition Description
Blue backed. Margins tattered, with minor soiling.
Oscar Lewis, George Davidson, Pioneer West Coast Scientist. (1954); (McArthur 1) Oregon Geographic Names:. Oregon Historical Quarterly, Vol. 26, No.4 (Dec 1925) pp 309-423; (McArthur 3) Oregon Geographic Names: Third Supplement. Oregon Historical Quarterly, Vol. 44, No.2 (June 1943) pp176-218.
United States Coast Survey Biography

The United States Office of the Coast Survey began in 1807, when Thomas Jefferson founded the Survey of the Coast. However, the fledgling office was plagued by the War of 1812 and disagreements over whether it should be civilian or military controlled. The entity was re-founded in 1832 with Ferdinand Rudolph Hassler as its superintendent. Although a civilian agency, many military officers served the office; army officers tended to perform the topographic surveys, while naval officers conducted the hydrographic work.

The Survey’s history was greatly affected by larger events in American history. During the Civil War, while the agency was led by Alexander Dallas Bache (Benjamin Franklin’s grandson), the Survey provided the Union army with charts. Survey personnel accompanied blockading squadrons in the field, making new charts in the process.

After the Civil War, as the country was settled, the Coast Survey sent parties to make new maps, employing scientists and naturalists like John Muir and Louis Agassiz in the process. By 1926, the Survey expanded their purview further to include aeronautical charts. During the Great Depression, the Coast Survey employed over 10,000 people and in the Second World War the office oversaw the production of 100 million maps for the Allies. Since 1970, the Coastal and Geodetic Survey has formed part of the National Oceanic and Atmospheric Administration (NOAA) and it is still producing navigational products and services today.

George Davidson Biography

George Davidson (1825-1911), was one of the most important mapmakers and scientific minds of the 19th Century.

Davidson was born in England and moved to the US in 1832.  He met Alexander D. Bache in 1842, when he assisted Bache in his observations of the magnetic elements at Girard College. Upon his graduation in 1845, he began his career as clerk to Bache who was superindentent of the United States Coast Survey. 

From 1846 to 1850, Davidson was occupied in geodetic field work and astronomy on the east coast. In 1850, he went to California, where he was engaged in the determination of the latitude and longitude of prominent capes, bays, etc., and of the magnetic elements of the Pacific Coast, including a survey of Washington and Puget sounds, and the main triangulation of the coast in the region of San Francisco. 

From 1861 to 1867, he was again on the Atlantic seaboard, principally engaged in engineering work on coast and river defences.  In 1866, he became chief engineer of an expedition for the survey of a ship canal across the Isthmus of Darien.

In 1867, he was appointed to make a special examination and report upon the geography and resources of Alaska, pending its purchase; his published report and conferences with congressional committees influenced the passage of the bill. He was placed in charge, during 1867, of the work of the Coast Survey on the Pacific, planned work for the land parties from 1868 until 1875, and inspected all the fields of work.  

From 1876 to 1886, he had charge of the main triangulation and astronomical work on the west coast; the records of the computing division showed that the results of his observations stood higher than any ever executed in America, Europe, or India, and they were characterized as “unique in the history of geodesy.

In 1881, Davidson twice measured the Yolo base line, one of the geodesic base lines that formed the foundation of triangulating distances in California. At that time, it was the longest base line yet attempted in trigonometrical operations, and the system of triangulation directly connected therewith was called in his honor the “Davidson quadrilaterals.” He also measured the Los Angeles base line three times in 1888-1889. He retired from the Coast Survey in 1895, after 50 years of service.

Davidson also founded the Davidson Observatory in San Francisco, which was the first astronomical observatory on the Pacific coast of North America, and in 1869 brought the Pacific geodetic of the coast survey in telegraphic longitude connection with Greenwich. His astronomical work includes the observation of the total solar eclipse under the 60th parallel, in 1869; determination of the 120th meridian in 1873; charge of the U. S. transit of Venus expedition, in 1874; recovery of the transit of Venus station of 1709 in Lower California occupied by Auteroche de la Chappe; observation of the total solar eclipse of January 7, 1880; and in 1882 charge of the party to observe the transit of Venus in New Mexico.

Other positions held by Davidson include president of the California Academy of Sciences from 1871 to 1887, Honorary Professor of Geodesy and Astronomy, and Regent of the University of California from 1877 to 1885. After his retirement from the Coast Survey,[4] he became the first professor of geography at the University of California, Berkeley, and chaired that department from 1898 until his retirement in 1905, and remained an emeritus professor until his death. Davidson was one of 182 charter members of the Sierra Club in 1892 and served as a member of its board of directors from 1894 to 1910.