1597-98 Cernoti

This version of Ptolemy from 1597-98 shows how long into the 16^th century Ptolemy continued to provide a framework for depicting the new world discoveries.

Figure 1 is the title page.

Figure 2 contains the Ptolemaic projection mentioned earlier in the exhibit.

Figure 3 contains what appears to be the Ortelius projection. Look at how similar it is to the 1571 Ortelius, figure 2 map.

Figure 4 depicts modern day Russia as "Tartaria". The American continent seems in close geographical proximity to Japan.

Figures 5 and 6 appear to constitute the Mercator projection, which projects the earth's surface onto a cylinder. Note how close the map in Figure 6 is to the famed 1569 Mercator map. This projection creates greater and greater distortion as one approaches the earth’s poles.

“The principal geometrical property of Mercator’s great map was designed for navigation: all rhumb lines were projected as straight lines on the map. On a chart, this meant that a navigator could set down a rule between two points and find the compass bearing that would take him along the indicated course.” Very Short Introduction.

Concerning its navigational usefulness, Gaspar (2016) claims that "...Mercator’s world map of 1569 was useless for navigation at the time it was created because navigation was something different from his idealised concept."

More generally, concerning navigation, one of the challenges was to develop a way to accurately determine longitude. Apian and Galileo, both of whom figure in this exhibit, worked on this issue.

In a related vein, Woodward (p. 13) claims that "Geographic coordinates were ... mainly of scholarly and not practical concern until reliable astronomical measurements of both longitude and latitude became available in the late eighteenth century, after a satisfactory chronometer had been developed. Coordinates and projection grids certainly were powerful rhetorical devices in the fifteenth and sixteenth centuries, but the data behind them was often questionable." See "The Longitude Prize" in this context, as well as the mention here for mention of Apian. This page describes Galileo's effort to gauge longitude; to show "that Jupiter and its moons could be observed on unstable ground, such as a ship's deck, Galileo designed a special helmet carrying a small telescope on a hinged mount."