Markers in the Woods

Markers in the Woods. . Placed here in 1850, this granite monument marks the western end of the Edisto baseline. Its mate still stands 6.68 miles east of this spot. They are among the few surviving end-point monuments of the seven baselines the U.S. Coast Survey measured in the 1830s through 1850s., So, just how accurate was Professor Bache's old measurement? To find out, mappers in the 1990s re-surveyed the line using America's $10-billion Global Positioning System., What Bache's team had labored over for weeks, GPS measured in one hour. Though the speed of the work was dramatically different, the accuracy was not. The Bar of Invariable Length had produced a line less than 2.5 inches from perfection , not bad for a nearly 7-mile length!, (captions) , Edisto's baseline was the third critical line that Prof. Bache measured between Maine and the Gulf of Mexico. When this marker was rediscovered, the Edisto baseline was the oldest Bache line still intact., Stamped in the before its 1850 installation, this granite monument was brought by sailing ship from New England. The Journal of Measurement of the Edisto Base, January 1850