The oldest published map of what was to become New Mexico can be found in an atlas published in 1597 by Cornelius Wytfliet, who served as secretary for the council of the duchy of Brabant in the Netherlands. Apparently information about the existence of Indian pueblos on the Rio del Norte first reported by the Coronado expedition of 1540/42, and later by Chamuscado-Rodrguez in 1581/82, Espejo in 1582, Castao de Sosa and others in the early 1590s had found its way to European mapmakers, most likely when Spanish nautical charts were highjacked by pirates. Wytfliet called the area Granata Novo, and while he had placed it roughly into the proper geographic position, the ten pueblos shown are purely speculative. A copy of that interesting map can be found on the Internet under Wytfliet.
In the Archives of the Indies in Seville is the oldest map of New Mexico prepared from reliable information by people who had been there. Enrico Martnez, a cosmographer in Mexico City, drew the map in 1602, a year when Don Juan de Oate still had his colonys capital at the confluence of the Rio Chama and Rio Grande at San Gabriel, seven years before the founding of Santa Fe. The map has the appearance of a rough draft and was never meant for printing and publication. Spain was very secretive about its maps and jealously kept them from falling into the hands of its rivals. More than fifty years later in 1658, on a map by a famous French geographer that first revealed the location of Santa Fe, the Rio Grande was shown originating from an imaginary lake in latitude 40 degrees and flowing southwest into the lower part of the Gulf of California, Baja California being shown as an island. Wytfliet too assumed that the upper Rio Grande and lower Colorado was the same river, but correctly showed Baja as a peninsula.
Chamuscado reports taking the latitude, probably with an astrolabe or with a ballestilla, as the Spanish called the cross-staff. At the time of Oates entrada in 1589, the route from the northernmost Spanish outpost at Santa Barbara in what is now southern Chihuahua, to the Rio Grande pueblos was reasonably well known. From his base in San Gabriel in the summer and fall of 1501 Oate went to explore the country to the east, all the way to Kansas. With him went a sailor by the name of Juan Rodrguez who returned to Mexico City in early 1602, where he reported on the nuevo descubrimentos (new discoveries) of the villages of the Wichita. In Mexico Rodrguez was put in touch with a certain Enrico Martnez, who combined the new data with the information already known and prepared the subject map (he called it a sketch) for the benefit of the viceroy.
Enrico (or Enrique) Martinez was a German engineer, illustrator and writer. Born Heinrich Martin in Hamburg in the second half of the 16th century, he went to Mexico in 1589 to become Royal Cosmographer and interpreter for the Holy Office. There he Hispanicized his name and became famous for publishing a natural history of New Spain and for investigating the watershed of the valley of Mexico City, where he designed and built dams and subterranean structures to protect the city from flooding.
The Martnez map covers twenty-three degrees of latitude, shown as tick marks on the left margin from 19 to 42. The north-south centerline of the map is formed by the 268th degree of longitude, the only longitudinal line shown. It was reckoned from the meridian of the Andalusian seaport of Cdiz, which was used by the Spanish as prime meridian, from which they counted east around the globe. 268 degrees from Cdiz correspond to about 9818′ west of Greenwich. Its intersection with the 29th degree of latitude divides the map into four quadrants, the southeastern of which contains a numbered list of twenty-five pueblos. A dotted line indicates the travel-route of Oates party on what would become the celebrated camino real, shown here from Mexico City to the crossing of the rio del norte in about the future location of El Paso.
The pueblos of New Mexico are shown as small triangles or tiny pueblo-style buildings. The headquarter pueblo of San Gabriel is circled and the building bears a cross. Some of the pueblos shown on the map no longer exist, nor have all been identified. The map also shows the Rio Chama (rio sama), Canadian River (rio de la madalena), Arkansas, Rio Conchos and a few others. A chain of mountains is indicated from about the location of modern Chimayo to the south end of the Manzanos, but these names do not appear on the map.
Since I have not seen the original copy of the map I cannot say anything about the scale to which it was drawn. The line of the 268th meridian together with the marks of latitude make it possible to scale the geographic positions of the features shown, but scaling distances of that map has its problems. On the lower right margin is a bar scale covering 150 leagues in 10 league increments. The league used is the old Spanish travel league (legua comun) of 20,000 Castilian feet (6,666.67 varas) or about 3.46 miles. The true size of the globe was not known in 1602 and was underestimated; therefore by scaling the interval of the tick-marks for latitude, one degree of latitude corresponds to about 61 3/4 miles, seven miles short of the true value. If one uses the location of Mexico City as a reference, the convergency of meridians at the latitude of San Gabriel is about 60 miles. By assuming that Martinez intended the meridians to run parallel the pueblos are plotted to within less than one degree of true longitude.
To the modern observer the map provides a wealth of information about the surveying and mapping skills available in Oates time. It is tempting to speculate that sailor Juan Rodrguez not only had navigational skills but also may have been employed by his superiors to keep track of their location. Perhaps he had a ballestilla and took the latitude, in any case, he knew that his party had been in latitude 40 degrees. Also, the location of the big bend of the Canadian River is nearly correct.
The latitude of the crossing of the Rio Grande near El Paso corresponds to the modern value. Most of the Rio Grande pueblos are plotted in their correct latitude to within degree (exceptions are Picuries and Taos which are plotted 1 degree too far north). The location of the south end of the Manzano Mountains, around which Oate had to pass on his trip east, also is correct.
The longitude is an entirely different matter. At the dawn of the 17th century Galileo had not yet build his telescope, and until his compilation of data on the moons of Jupiter and the position of the (earth) moon there was no known method to establish longitude by astronomical observation. Mercator had suggested to use the variations of the compass needle, assuming that it changed at a uniform rate with longitude, but the proposal proved impractical. Time could not be carried across the Oceans. This left dead reckoning, which was based on the estimate of a ships speed. While it has sometimes been called not much better than guessing, as practiced by a skilled navigator it was better that is often believed. On the Martinez map the coastline at the important port of Veracruz is placed only about 100 miles too far east, not bad reckoning after almost 6,000 miles at sea. It would take another two centuries before the location of longitude on maps of North America would become much better than that.
A copy of the Martinez map can be found in Kiva, Cross, & Crown, published by John L. Kessell of the National Park Service, and in The Rediscovery of New Mexico by Hammond & Rey, published by University of New Mexico Press.