Maps for Mariners
Charts for Marylanders
Chartmaking I
Chartmaking II
The Language of Charts

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Charting the Chesapeake:  1590 -1990

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Chartmaking I: Copperplates to Computers

Just as methods of surveying have changed over the past four hundred years, so have the techniques of actually producing the charts. Chartmaking covers a wide spectrum from the earliest unpublished manuscripts to the mass-produced charts of today.
The Copperplate Process

Map and chartmakers preferred to use copper for engraving because it was stable, yet soft enough to permit correcting. They used copperplates for map and chart reproduction for well over three hundred years, during the seventeenth, eighteenth, and nineteenth centuries. This process reproduced maps with intricate detail and tone variations.

The process involved the following:

  • The chartmaker incised the features of the chart into the surface of the smooth, polished copper plate. Using a sharp tool, he cut the lines, removing a narrow vee-shaped section from the surface. This was a painstaking, slow, and expensive procedure, made even more difficult by the fact that it had to be done as a mirror image.
  • The chartmaker applied ink to the entire surface of the copperplate, making sure the ink filled the incised design.
  • He wiped off the excess ink, leaving a small amount in the incised design and lettering.
  • Next, he placed a sheet of paper over the plate. The paper was slightly moistened to make it more flexible.
  • The chartmaker placed padding (often sheepskin) over the paper, pressing it firmly against the paper and plate so that the paper made contact with the inked incised areas. This was usually done by racking the plate, paper, and padding between metal rolls.
  • Finally, the chartmaker removed the padding and stripped away the paper which bore ink from the incised areas.
Engraved drawing of a printing press
William Blaeu employed the best pressmen, engravers, scribes and colorist in the Netherlands. His types were clean and well cut while his paper was heavy and of good quality. Blaeu designed and built an improved printing press.
Reproduced from The Story of Maps by Lloyd A. Brown, 1949.
Woodcut illustration of a cartographer at work
An early woodcut illustration of a cartographer at work. From Paul Pfintzing's Methodus Geometrica, first printed in Nuremberg, 1598.
Reproduced from The Story of Maps by Lloyd A. Brown, 1949.

Lithography is a printing process that was introduced in the United States from Europe during the early years of the nineteenth century. Since the process was faster than copperplate engraving the U.S. Coast Survey used lithographic printing to fill the great demand for charts at the start of the Civil War.

The process involves the following:

  • The image to be printed is rendered with an oily or waxy material on a flat surface. Early lithographers used a smooth stone for this purpose while sheet zinc or aluminum is used now. As with copperplate engraving, the chart is drawn as a mirror image.
  • The chartmaker dampened the stone, then rolled ink over its surface. The ink adhered to the image but was repelled by the dampened parts.
  • Placing a sheet of paper on the stone, the chartmaker passed the stone and paper though a press.
  • He peeled away the paper which carried the inked image.
Carta Particolare Della Virginia Vecchia E Nuoua, Sir Robert Dudley, 1646, MSA 1399-1-536
Carta Particolare Della Virginia Vecchia E Nuoua
Sir Robert Dudley
Florence, Italy, 1646
Huntingfield Corporation Map Collection, MSA SC 1399-1-536

This was the first chart of the Chesapeake area to use the Mercator projection. It and others in the rare marine atlas Arcano Del Mare are considered among the most beautiful engraved charts of the seventeenth century. The copperplate engravings in the atlas took twelve years to make and used five thousand pounds of copper.

Virginia partis australis,  William Janszoon Blaeu, 1640, MSA SC 1399-1-563
Virginia partis australis...
William Janszoon Blaeu
Amsterdam, 1640
Huntingfield Corporation Map Collection, MSA SC 1399-1-563

This is an example of a beautifully engraved chart from the Dutch publisher William Janszoon Blaeu and his sons John and Cornelius. Blaeu was a highly respected man of science who held the title of Map Maker to the Republic. Yet many of his maps and charts, such as this one, are not scientifically accurate. Some scholars believe that Blaeu was a shrewd businessman who made two kinds of charts: one to please the eye that tended toward bright colors and gold leaf; the other for seamen and officials who knew and demanded the best in scientific documents. Blaeu's working maps and charts were most likely worn out or destroyed as a safety measure, while his beautiful maps and atlases, because they were locked up in a gentleman's library and never disturbed, have survived.

Patuxent River Maryland, Lower Part,  U.S. Coast and Geodetic Survey, 1987 Patuxent River Maryland, Lower Part
U.S. Coast and Geodetic Survey
Washington, DC, 1897
National Oceanic and Atmospheric Admin., National Ocean Survey

This print was made directly from the a copperplate. It is the same basic chart as the 1859 preliminary chart of the Patuxent River but it includes topographic characteristics. It also includes two lighthouses that did not exist in 1859, Drum Point Lighthouse and Cedar Point Lighthouse, marking the entrance to the Patuxent River.

Bathymetric Map--Chesapeake Bay:  Potomac River Entrance--Plate 8  National Ocean Service, 1970, MSA SC 1399-1-743
Bathymetric Map -- Chesapeake Bay: Potomac River Entrance--Plate 8
National Ocean Service
Washington, DC, 1970
Huntingfield Corporation Map Collection, MSA SC 1399-1-743

This colorful map is an example of a modern printing chart. Its coloring illustrates the Chesapeake Bay as a drowned river valley with a narrow, deep channel. The Bay was formed when the Susquehanna River flooded 15,000 years ago with the melting of the glaciers in the last ice age.


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