In 1863, the U.S. Coast Survey conducted triangulation, baselines, and astronomical observations in the Perry vicinity, then calculated latitude and longitude for stations that became the foundation of charts and maps used to aid navigation. In 1883, topographers Alexander Wadsworth Longfellow and Charles Meigs Bache recorded bends in the shoreline and used a plane table to connect the points while mapping the coastline, accidentally finding that a local chimney in Perry stood very near the 45th Parallel and marking the spot with a brass rod. In 1896, local citizens, proud of the Coast Survey's exacting work, commissioned and erected an adjacent granite monument to mark the parallel. This latitude lies nearly halfway to the North Pole and links Perry, Maine, with Bordeaux, the deserts of Mongolia, the northernmost tip of Japan, and Salem, Oregon. Today, precision mapping still connects points to create accurate maps, but instead of using the stars as Victorian-era surveyors did, the Global Positioning System uses a constellation of satellites to determine precise locations on the earth's surface.