Chuck Neudorf
Iteration #2
WD CT 1000:1500



What I propose to do for my Blue Rabbit project is to blur the temporal aspect of technology. I hope to use new technology to create an old tool that can solve problems in today’s world that were first solved long ago. Further, I hope that the use of this tool will foster an understanding of how the world works. Additionally, I would like to look at how tools extend the mind of the user.

The tool I am making is a plumb bob sextant, a precursor to the marine sextant. It is a simple tool that measures angles above the horizontal plane using a plumb bob as a vertical reference. It is a simple, yet remarkable tool. It can be used to determine the height of a building or a mountain. It can also measure the height of a celestial body above the horizon to determine latitude. Before the early eighteenth century, this was as good as navigation tools got. That is, most of the Earth was explored with tools no more accurate then the plumb bob sextant.

I am a navigator. I have had the responsibility of finding a path across an ocean, without electronic aids to navigation. The tools I used were more sophisticated than those that I have 3D printed, but the principles are the same. Using the tools and the algorithms of navigation is one of the most interesting and rewarding things I have done.

While it is called a plumb bob sextant, the device I have made is actually an astrolabe. The difference is that a sextant measures an angle relative to the horizon where an astrolabe measures an angle relative to a vertical line established by gravity. Neither instrument is more inherently accurate than the other, but because of ease of use, the sextant can generally produce more accurate results.

There are records of astrolabes as early as 150 BC, but it wasn’t until advances in sail configuration, hull design, and magnetic compasses that navigators had the tools necessary to explore the planet. Instructions for the use of the astrolabe came from some notable sources. “The simplest and most available English work on the description and use of the astrolabe is the “Tractatus Conclusionibus Astrolabii” written be Geoffrey Chaucer in 1391 and 1392.” (Latham). Historically, mariners had to stay within sight of land, but once the tools were in place, that changed. “The application of the astrolabe, and the abandoning of the time-honored route of exploration, along the African coast, for steering a bold course westward in pursuit of Cathay and fabled lands as yet unexplored, resulted in the addition of a continent in the greatness and progress of which the Old World, while admitting a sister in the family of nations in the present is already looking for a rival in intelligence wealth and progress.” (Journal of the American Geographical Society of New York). The ability to sail out of sight of land for weeks at a time, and yet still know ones position, led to the great voyages of discovery of the 14th through 16th centuries. Early in the 18th century, two inventions made marine navigation easier and more accurate. The sextant and chronometer together, allowed longitude to be calculated, where before it was estimated. While a reasonable replica of a sextant can be made with a 3D printer, the chronometer is out of the question. Consequently, I’m drawing the line in the sand of technology at the early 18th century.

For navigation purposes, an astrolabe works by measuring the angle of a celestial body above the horizon. There are only two targets we are interested in, Polaris (the North Star), and the sun. Given a few constraints, if we measure the height of either of these bodies, we can determine our latitude. The number we get from the astrolabe is not a direct reading so we’ll have to do some calculations. Don’t worry, nothing more than some addition and/or subtraction. One of the great things about this system is that it requires you to understand some of the basic facts of the solar system. You have to understand that Polaris is directly over the North Pole. You have to understand how the suns path changes throughout the day, what defines the tropics and the seasons, and even which way the Earth spins. You really get to know your home planet.

Our discussion so far has been Eurocentric, but the exploits of the Polynesian navigators were every bit as impressive. They used different navigation concepts and very different boats. Where Europeans plotted the advancing position of their vessel on a static chart, the Polynesians saw themselves as being at the center while the stars and islands and other navigational clues were in motion around them. The European strategy was to formalize the tools and teachings of navigation while the Polynesians relied on an oral tradition. Between the two cultures, there was a large difference in opinion as to what constituted a proper ship. “To the European mind the only seaworthy vessel is one made buoyant by a watertight air-filled hull, so big and high that it cannot be filled by the waves. To the ancient Peruvians the size was of less importance; the only seaworthy craft was one which could never be filled by water because its open construction formed no receptacle to retain the invading seas, which washed through.” (Heyerdahl)

The Polynesians were able to not only explore but to colonize the vast expanse of the Pacific basin before the Europeans even saw the Pacific. “We could trace the introduction of these Amerindian alleles to before the Peruvian slave trades, i.e. before the 1860s, and provide suggestive evidence that they were introduced already in prehistoric time. Our results demonstrate an early Amerindian contribution to the Polynesian gene pool on Easter Island, and illustrate the usefulness of typing for immunogenic markers such as HLA to complement mt DNA and Y chromosome analyses in anthropological investigations.” The extent of Polynesian influence reached all the way to the Americas.

It is easy to see how the two cultures differed in their approaches to navigation. My attention now turns not to the similarities of mechanics but to the similarities of being. How do you set off on a voyage of exploration? What lessons are learned when travelling on the open sea? “For scientists studying how humans come to understand their world, the central challenge is this: How do your minds get so much from so little: We build rich causal models, make strong generalizations, and construct powerful abstractions, whereas the input data are sparse, noisy and ambiguous-in every way far too limited. A massive mismatch looms between the information coming in through our senses and the outputs of cognition.” (Tenenbaum)


What of the mind of the navigator? If the Polynesian and the European reach the same goals but use different tools, are the respective tools responsible for the same or different extensions of the mind. How does time affect these questions? When I sailed down the trades to Hawaii thirty years ago, how connected was my mind to Jack London’s who had sailed the same route 100 years ago; or with George Vancouver who sailed the route 100 years before him? It is said that the measure of a navigator is his demeanor when he has no idea of where he is. That is something, I believe, we all share.

My project starts with things that I am comfortable and familiar with. Soon enough, I find myself with lots of questions and few answers. I don’t really even have a strategy for finding some of these answers. It’s okay. I’m a navigator; I’ll just keep forging ahead and not let anyone know that I’m lost. No sense in all of us being panicked.




The Astrolabe
Marcia Latham
The American Mathematical Monthly, Vol. 24, No. 4 (Apr., 1917), pp. 162-168
Published by: Mathematical Association of America
Article DOI: 10.2307/2973089


Transactions of the Society for 1872
Journal of the American Geographical Society of New York
Vol. 4, (1873) , pp. 35-56
Published by: American Geographical Society


The Balsa Raft in Aboriginal Navigation off Peru and Ecuador
Thor Heyerdahl
Southwestern Journal of Anthropology, Vol. 11, No. 3 (Autumn, 1955), pp. 251-264
Published by: University of New Mexico
Article Stable URL:


The Polynesian gene pool: an early contribution by Amerindians to Easter Island
Erik Thorsby
Philosophical Transactions: Biological Sciences, Vol. 367, No. 1590, Immunity, infection, migration and human evolution (19 March 2012), pp. 812-819
Published by: The Royal Society
Article Stable URL:


How to Grow a Mind: Statistics, Structure, and Abstraction
Joshua B. Tenenbaum, Charles Kemp, Thomas L. Griffiths and Noah D. Goodman
Science, New Series, Vol. 331, No. 6022 (11 March 2011), pp. 1279-1285
Published by: American Association for the Advancement of Science
Article Stable URL: