Three days ago we were accorded the rare privilege of touring the Royal Observatory of Spain in Cadiz.

Founded in the late 18th century Spain’s Royal Observatory served (and continues to serve) the same purpose as the Greenwich Observatory in England – providing an accurate source of time for the navy and country.

Unlike Greenwich, the Royal Observatory of Spain is on a restricted access military base and is not open to the public. So it was through special arrangement that our eclipse group was able to visit and receive a guided tour as part of our day in Cadiz.

Above is the main observatory building, which today houses a telescope and laser range finding system for geodesy work. On display were a host of brass telescopes and surveying instruments from the 18th and 19th centuries.

Above, in another observatory building, we saw a classic 12-inch astrographic refractor, used to take early photos of the night sky on glass plates, as part of the international Cartes du Ciel program in the 19th century.

This is the readout of the precise time, being maintained by cesium clocks in a climate controlled room next door.

The real treat was a tour through the Observatory’s library, a national treasure. Some 40,000 volumes date from as far back as the invention of the printing press in Gutenberg. The collection includes books on every science and engineering subject, and reports from all the historic science expeditions of the time.

One volume, shown here, is a 1514 book of eclipse tables.

Another case held early editions, often annotated by their owners, of the seminal works by Copernicus, Galileo, Kepler, and Newton. We were very impressed.

Tomorrow our cruise ship docks at the Canary Islands, then we sail southwest with the trade winds to meet the shadow of the Moon on November 3 at latitude 18°06′ N and 39°19′ W.

– Alan, October 24, 2013 / © 2013 Alan Dyer (posted from at sea north of the Canary Islands)