History buffs and land surveyors from across the US, and as far away as Great Britain, will rendezvous in a farm field south of Gettysburg, Pennsylvania on Saturday afternoon, October 19, for the planting of an elaborate new Mason-Dixon Stone.

Nearly a century before Robert E. Lee's army marched into Gettysburg, Charles Mason and Jeremiah Dixon - amazing British astronomer-surveyors - came through setting boundary stones. They were marking the border between Maryland and Pennsylvania, still English colonies at the time. In October 1767, along what later became known as the Mason-Dixon Line, they set their "Crownstone 75," in towering wilderness near present-day Gettysburg, Pennsylvania. Most of the boundary stones Mason and Dixon set 235 years ago still exist - but Crownstone 75 disappeared.

On Saturday afternoon, October 19, land surveyors, historians, astronomers, authors, Mason-Dixon enthusiasts and the public at large will gather at the exact same spot on the Mason-Dixon Line, to install a 525-pound full size replica of the missing original. The site today is a farm field.

The new Mason-Dixon Stone will be dedicated to the memory of Emmitsburg, Maryland surveyor Robert F. Gauss Sr., a great Mason-Dixon Line enthusiast and well-known civic volunteer in Emmitsburg, who was a leader of his surveying profession in Maryland and died May 21, 2000.

Six professional organizations of land surveyors from Pennsylvania, Maryland and across the nation paid for the stone and are hosting the event. For more than a year, flawless Replacement Crownstone 75 has been "on tour" throughout the mid-Atlantic region, promoting its reenactment ceremony far and wide.

On October 19 the new stone will be brought up on a period-authentic 1760s horse-drawn wagon, hoisted into position with a wooden block & tackle on a timber tripod, then lowered onto its carefully-surveyed correct boundary spot (beneath which a long-buried fragment of Mason and Dixon's original stone was found by local surveyors in August).

Charles Mason was a world-class astronomer and geodesist, Jeremiah Dixon a superb English surveyor. Together, they made up the British Royal Observatory's top "overseas assignment" team - accomplished experts who sailed the globe for England and science. In 1763 they answered a troubled plea, from two of His Majesty's far-off American colonies, Pennsylvania and Maryland, seeking skilled assistance in laying out their vast, complex wilderness boundary. The job was estimated to take 18 months. Six years later Mason and Dixon completed it - one of the most remarkable boundary surveys ever conducted on earth. The two and their accomplishments are still revered by surveyors and astronomers worldwide.

To reach the ceremony, take US Route 15 toward Gettysburg, Pennsylvania. Turn south on State Route 134, away from Gettysburg. Proceed 4.5 miles to the town of Harney, Maryland. At the outskirts of Harney, turn left into the fire department's carnival grounds, across from Harney Volunteer Fire Department. The entrance will be marked. Surveyors will direct you from there to the ceremony site, within easy walking distance.