Ledia Carroll – Determining Latitude

Ledia Carroll w woodwork array by Paul Cesewski, Determining Latitude , Sheetrock, Wood, Glass, Guache Marker, Sept 2011 showed Sept 30 2011 to Dec 30 2011 at the Philadelphia Art Alliance as part of a boat inspired group show http://www.philartalliance.org/exhibition/let-me-tell-you-about-a-dream-i-had-the-miss-rockaway-armada/

This piece is called Determining Latitude which is named after the view through a sextant (used for celestial navigation before GPS). We cut a hole through the sheetrock revealing view through an old window. One of the most interesting things about traveling with the Rockaway Armada has been the information we always seek about waterways for navigational purposes. Because we have travelled on mostly rivers, we have used land sights and navigational maps primarily, as well as talking w knowledgable locals and of course tide charts when traveling on tidal rivers.

Our piece, Determining Latitude was inspired by Ledia’s study of the ancient celestial navigational techniques that emerged over the last several millenia to location their position on the globe, on water or land. Celestial navigation uses angular sightings measured between a celestial body and the visible horizon. Navigators usually use the sun but many trips across oceans have been undertaken using the moon, planets or stars. The “noon sight” is one of the oldest techniques used before accurate clocks were available. Since it is relatively straightforward and doesn’t require use of tables on the position of the sun and stars, it has been commonly in use until the more recent availability of GPS.

About Determining Latitude via Celestial Navigation: “The first thing navigators of long ago learned to do was to determine latitude from the position of the sun at noon. You may remember from your reading of old sea tales the phrase “running down the latitude” until landfall was made. Latitude cd be determined without accurate time by just waiting until the sun reached its highest point in the sky at noon. Longitude was not easily ascertained until a proper timepiece was developed for use at sea. The navigator would therefore take his ship to the latitude of his destination and then run east or west as the situation warranted until he arrived. Today. with the availability of correct time at sea via timepiece or radio, we can obtain an exact latitude and fair longitude w the one noon sight. ” from Celestial Navigation by John Milligan, Cornell Maritime Press 1974

(Note: I am planning to install this piece again w a clearer view of the navigational markings painted on window (which you cant see in this image), making the oculus smaller, less centered in the visual field of the room, and build a ladder w a bench you have to get up to it, and ideally put in a position where the light dances on the floor of the room again in which the light acts as a sundial. I also built a water box to look through that didn’t work for this installation but looking forward to building another version of it. )