Among the urgent needs of the Continental Army was the need for maps in
multiple copies for the prosecution of the war. Colonial American map
makers had always relied on English engravers and printers to engrave and
publish their maps because of the lack of adequate facilities for
reproducing them in the colonies. Maps produced by this means were in
very short supply in the colonies and there was no possibility of developing
adequate facilities in wartime. It had been General Washington's good
fortune to have met Robert Erskine in the summer of 1777. Washington
recommended him to the Continental Congress to become the Geographer
and Surveyor General of the Army.
Erskine gradually assembled a corps of more than twenty surveyors, in addition
to an adequate complement of chain-bearers and other assistants. It was a
herculean task because many of the men skilled in the art had been drafted or
were assigned to other priorities. Erskine and his staff issued more than 130
different maps between the time of his appointment and his death three years
later. For the most part, the maps were first sketched upon a plane table in a
roughly finished form. They delineated the roads and primary topographical
features as well as commanding elevations and identification points such as
churches and taverns. Although crudely executed, the maps proved to be
surprisingly accurate. They were subsequently contracted in size in a new
compilation produced at a reduced scale, plotted on a grid of conic projection
based on the prime meridian of New York City, taken from its City Hall.
The work of the surveyors was extremely hazardous, for not only were they
subjected to the dangers of inclement weather and wildlife, but they faced danger
from the enemy as well. General Washington was alert to these problems, and
provided such assistance of which he was capable. While Erskine's staff was
mapping the Hudson Highlands, for example, Washington directed General
James Clinton to move towards the enemy lines in the direction of Kings Bridge
"to cover the Engineers and Surveyors, while they reconnoiter . . ."
Despite the growing success of Erskine's operation, it did not totally resolve the
cartographic problems of the Continental Army. Multiple copies of the maps
were needed for the prosecution of the war and had to be distributed to staff
officers and others. The small field sketches produced by the cartographers or
surveyors were supplemented with notes compiled hurriedly in the field, which
generally incorporated many abbreviations liable to misinterpretation. These were
submitted to professionally trained draftsmen who assembled the individual
sketches and rendered them into the required composite form, then delineated a
final map supplemented with the information provided in the field notes. Each of
the products was an individual project and resulted in a single document. From
this final map, individual copies had to be made painstakingly by hand in sufficient
numbers to supply the staff. Inasmuch as they had to be kept out of enemy
hands, only the officers of the highest rank received copies. Duplicating methods
that became popular after the turn of the nineteenth century were not yet
developed, and in this time of war there was no capability for engraving and
printing of the maps. A manuscript list in Erskine's hand summarizing his maps,
totaling 129, is preserved in The New-York Historical Society, together with the
major portion of the maps themselves.
On September 18, 1780, while engaged in making some surveys of the Hudson
Highlands, Erskine caught a severe cold and sore throat which produced a fever
and within two weeks brought about his death on October 2, 1780. That same
day Major John Andre was executed as a British spy about twenty miles away at
Tappan. Erskine's coffin plate was produced by his assistant and devoted friend
Simeon De Witt, and contained the following inscribed in gilt letters:
In memory of
ROBERT ERSKINE, F.R.S.
Geographer and Surveyor General to the Army
of the
United States of America.
Born Sept. 7, 1735. Died Octover 2nd, 1789.
Aged 45 years and 25 days.
Erskine was buried at his home at Ringwood, his resting place marked with a
brick table tomb topped with a marble slab, said to have been caused to be
erected by General Washington. The same words inscribed on his coffin plate
comprise the epitaph upon the marble slab, with an additional sentence:
Son of the Rev. Ralph Erskine, late minister at
Dunfermline in Scotland.
Despite the importance of Erskine's contributions to the success of the American
Revolution, relatively little effort has been made to organize his papers, and
record his life and work. There has been but one biography which was poorly
done, Robert Erskine, The Forgotten General by Albert H. Heusser,
published in 1928 by Rutgers University Press. In 1966 the work was edited and
many errors corrected by Hubert G. Schmidt in a revised edition titled George
Washington's Map Maker. A Biography of Robert Erskine.
The New Jersey Gazette of October 18, 1780 memorialized Erskine as: ". . . a
man in whom were united the Christian and the gentleman. His integrity
and unbounded benevolence have rendered his death a loss to the publick,
and a subject of sincere regret to all his acquaintances. He made the laws
of justice the invariable rule of his conduct, and upon this principle
espoused the cause of America, in which he served his country with
approbation and universal esteem."
