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The Mapmakers: An Essay in Four Parts
Mapmaking
17th Century
During the early 17th century, mapmaking took a huge leap forward. The instruments had improved; mathematical and astronomical concepts necessary to making accurate measurements had evolved; observers were better trained; and -- very importantly -- strong motives had arisen to make accurate maps.
Before the close of the 16th century, English mathematicians had perfected triangulation (navigation and surveying by right-angled triangles) through plane trigonometry. This development allowed navigators to set courses on any compass angle and permitted surveyors to produce much more accurate surveys on land. Although the mariner's compass remained in use, most compasses were now manufactured to read in degrees as well as points, permitting finer observations and the use of trigonometric tables. The better seamen learned how to correct their compasses for declination and early in the century the English had determined the existence of annual compass variation.
Latitude determination was greatly improved with John Davis's invention (ca. 1595) of the back-staff (Davis quadrant). It was further developed over time and remained unsurpassed until the invention of John Hadley's reflecting quadrant (1731). The measurement of distance sailed at sea was improved by another English invention, the common log. This device was a line, knotted at fathom (six foot) intervals and attached to a float. The speed of a ship was calculated by heaving the float off the stern and counting the knots as they ran through the navigator's hands during an interval of 30 seconds or a minute. The result was converted to distance over the time the wind speed was constant -- a great improvement over dead reckoning.
Longitudinal distance between Europe and Canada was determined by solar and lunar eclipses. A predicted eclipse would be timed in some European city (usually Paris or Rome) and at Québec. The difference in time between the two observations was calculated and converted to degrees at one hour per 15 degrees. This was an exacting procedure, but good results were obtained by the Jesuit Bressani in the 1640s and by Jean Deshayes in 1686. With fairly accurate surveys in Europe to determining the absolute length of a degree of latitude, and a decree being made by Louis XIII in 1634 to create for the first time a standard prime meridian for French maps (at Ferro, in the Canary Islands), the basic grid of the modern map began to take shape.
What lagged was the education and inclination of navigators and surveyors to take advantage of such innovations as triangulation, more precise compasses, the back-staff, and the common log. In this respect, England moved ahead much faster than other nations with the establishment of training centres for navigators late in the 16th century. In Quebec, in 1661, Martin Boutet became the first person appointed to teach applied mathematics at the Jesuit college. In 1666, the intendant, Jean Talon, broadened this appointment to include the teaching of navigation and surveying. Boutet was succeeded by Jean-Baptiste-Louis Franquelin in 1687 and Jean Deshayes in 1702. These were competent men who trained Canada's pilots, navigators and surveyors -- all of them mapmakers.
Early in the 17th century the French had decided to settle Canada and the English to explore a northern passage to Cathay. Both these interests required accurate mapping. In the North, men like Foxe, James and, especially, Baffin, were trained in the latest methods of producing accurate reconnaissance maps. In New France, Champlain prepared the first chart of the Atlantic coast to Cape Cod between 1604 and 1607, including potential harbours, using triangulation. From the first of two anchorages he would take compass bearings of a series of prominent features, then move his boat over a carefully measured distance to the second anchorage and take a second set of bearings of the same features. Each feature was now at the apex of a triangle of which he had the three interior angles and the length of one side. Triangles produced this way were transferred to a chart and the shoreline sketched in. Champlain did not understand trigonometry, but later mapmakers who did used the same principles and were able to make their maps more accurate than his. On land, the first property surveys and maps of the St. Lawrence shore were undertaken by Jean Bourdon with a combination refracting telescope and compass, a gift of the Jesuits. This forerunner of the theodolite permitted Bourdon to make accurate surveys with triangulation.
Explorers who travelled into the interior west of Montreal, first obtained Native maps and guides. These Native maps rarely appeared on French maps unless they were of areas the French had not yet seen. As the French advanced west, they made their own maps. Between Champlain's last map (1632) and the late 1670s the best maps were made by -- or based on the observations of -- the well trained and inquisitive Jesuits. The basic ingredients of these maps were latitude, compass readings and estimates of distance. The information that came out of La Salle's explorations and others toward the end of the century was, in some respects, not as good. While maps of the Atlantic coast and that of the St. Lawrence were achieving some accuracy, those of the interior west of Montreal were essentially rough reconnaissance maps. Notable on maps of the time, because they were of interest, were the lakes and river systems that served for transportation and the location of Native groups who were important as military allies, suppliers of furs and targets for missionaries.
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