Then, as now, the Earth wobbled on its polar axis, shifting True North here and there. In 1899 (above), Gaithersburg became the site of an observatory, one of eventually six built around the world near the parallel of 39 degrees 08 minutes north. These International Latitude Observatories measured the planet’s wobble by systemartically observing pairs of stars.
The observatories kept up their work until 1982, when satellites put them out of business. But Gaithersburg’s International Latitude Observatory, at 100 Desellum Ave. (right), continues its service. The data gathered there is still useful. And its U.S. Coast and Geodetic Survey markers aid Global Positioning Satellite (GPS) systems in making periodic course corrections.
—David Holzel
