Statistical Outlier
Last night I started The Visual Display of Quantitative Information by Edward Tufte, which is excellent. If you haven’t read it you may know it as the book featuring what I call the ‘Napoleon Graph‘, which Tufte calls the ‘best statistical graph ever drawn.’
But another graph featured in the book is even more interesting. It’s a tenth, possibly eleventh-century, depiction of the movement of the planets across the zodiac over time, and comes from a commentary on astronomy. The graph was included in an appendix added by an unknown transcriber of the main work. It’s not accurate at all—among many problems is the fact that the horizontal axis of any one planet can’t be reconciled with the others—but it was probably intended as a simple schematic for teaching purposes.
What’s really unusual here is that the graph has no known predecessor, and seems to have sprung purely from the imagination of it’s creator. Medieval writers and artists very rarely deviated from tradition. Most images, whether of scientific, medical, fictional, or religious subjects, were part of traditional illustrative cycles that had existed since the late classical period. There was some room for individual artists to maneuver within these tropes, but it was rare for something to appear completely out of the blue.
Not only is the graph unique, but it’s conceptually eight hundred years ahead of its time. According to Tufte, time-series charts didn’t appear again until the late eighteenth century, when academics and designers began experimenting with a variety of quantitative displays. And H. Gray Funkhouser, author of ‘A Note on a Tenth Century Graph’ in Osiris (vol. 1, Jan 1936) notes that the use of grids was uncommon even into the 1850s.
You can read Funkhouser’s short piece on the graph here if you have access to JSTOR. And here’s a larger image.
Sidereus Nuncius
I watched the lunar eclipse last night, standing in the yard with a pair of old birding binoculars. The sky clouded over completely just after the full eclipse, but I was able to see the first half of it pretty well. A telescope would have been better, but through the binoculars you can see well enough to get a nice sense of the Moon’s three dimensionality. I’ll have to remind myself to go out with the binoculars again on a clear night.
In the meantime, the Moon in antiquarian books:
- The University of Vienna offers a download of a 1515 Italian edition of Ptolemy’s treatise on astronomical mathematics, the Almagest, (The Great Book) which has two chapters on the movements of the moon and eclipses.
- An image from the Almagest hosted by the University of Minnesota:
- The Linda Hall Library has created Face of the Moon, a detailed online exhibit featuring scientific Moon images from the Renaissance through the 1970s.
- The CalTech Institute Archives has a large digital collection, including some of Galileo’s Moon images from the Sidereus Nuncius (the Sidereal Messenger) of 1610. This was first scientific work based on observations made using a telescope. Besides the Moon it includes studies of the stars and the moons of Jupiter.
- A Time Magazine article on watercolor sketches in a printer’s proof of Sidereus Nuncius which may be in Galileo’s own hand.
- Moon map by Johannes Helvius, 1647, from the digital collection of the U.S. Naval Observatory Library, which has made available a number of fantastic astronomical images:
