Chapter 2

The First Graph Got It Right

Synopsis

Who invented the idea of graphing data? This question is meant to be provocative and contentious. It is provocative, because you might wonder or argue about what “graphing data” actually means.

• what counts as “data”?
• what counts as a “graph”?

It is contentious, because like many other scientific discoveries and inventions, claims of “firsts” are difficult to pin down: many important discoveries were preceded by others that might count under a looser definition; conversely, those who followed often developed the same idea in wider or more general ways.

This chapter begins our journey through the history of data visualization with the story and context of what can be claimed as the earliest example of modern graphic depictions of statistical data.

A fundamental and difficult problem in the 17th century was determination of longitude at sea. A variety of methods were tried, but none were very accurate. To demonstrate the problem (and seek patronage from King Philip of Spain), Michael Florent van Langren had the idea to make a graph of historical determinations of the longitude distance from Toledo to Rome, in what is arguably the first graph of statistical data. This chapter shows why this was exactly the right thing to do.

Chapter contents

• Early Things Called “graphs”
• The Problem of Longitude
  
• Show Me the Money
• Van Langren’s Graph
  • Patronage and Grantsmanship
  • Eyes on the Prize
  • The “Secret” of Longitude
  • Van Langren’s Legacy

Selected Figures

Figure 2.1: The first statistical graph Van Langren’s 1644 graph of twelve determinations of the longitude distance from Toledo to Rome: The correct distance is 16.5°. Source: M. F. van Langren, La Verdadera Longitud por Mar y Tierra, Antwerp, 1644. Reproduction courtesy of the Koninklijke Bibliotheek van Belgie¨.

Figure 2.2: Graphs of functional forms A portion of a page from Oresme’s Latitude of Forms, showing three graphical forms arising from a functional relation between physical variables. Source: Nicole Oresme, Tractatus de latitudinibus formarum. Padua: Matthaeus Cerdonis, 1482.

Figure 2.3: Graphical inventions Timeline of the invention of some basic forms for statistical graphs, 1600–1850. Source: © The Authors. Rcode: 02_3-graphic-forms.R

Figure 2.4: Overlay Van Langren’s 1644 graph, linearly rescaled and overlaid on a modern map of Europe. Toledo and Rome are shown by markers on the map. Source: Map: Google Maps; overlay: M. F. van Langren, La Verdadera Longitud por Mar y Tierra, Antwerp, 1644. Reproduction courtesy of the Koninklijke Bibliotheek van België.

Figure 2.5: Cipher Van Langren’s cipher-text description of his solution to the longitude problem. This cipher has never been decoded. Source: M. F. van Langren, La Verdadera Longitud por Mar y Tierra, Antwerp, 1644.