Visit the Star-Gazers' Stone, the site of a temporary observatory established in January 1764 by astonomers Charles Mason and Jeremiah Dixon that they used in their survey of the Mason-Dixon line.
At the time, the colonies of Maryland (Calvert) and Pennsylvania (Penn) had a disputed border thanks to competing royal charters of the time. Maryland and Pennsylvania both claimed the land between the 39th and 40th parallels according to the charters granted to each colony, and this would have included the City of Philadelphia. The issue was unresolved until the British Crown intervened in 1760, ordering Frederick Calvert, 6th Baron Baltimore to accept a border agreement signed in 1732. As part of the settlement, the Penns and Calverts commissioned the team of English astronomers Charles Mason and Jeremiah Dixon to survey the proper boundaries between Pennsylvania, Maryland, Delaware and parts of Virginia.
The Mason-Dixon Line (the northern boundary of Maryland) was to be 15 miles south of the southernmost house in Philadelphia. On January 7, 1764, after finding the latitude of the house, they picked out a location 31 miles west of Philadelphia at John Harlan's farm in modern day Embreeville, Pennsylvania at the same latitude of the forks of the Brandywine Creek. Moving their delicate but heavy equipment took two days. They moved westward because surveying 15 miles directly south from Philadelphia would have involved a difficult crossing of the Delaware and would have landed them in New Jersey from which they would have to cross the Delaware again on the way west. It made more sense for Mason and Dixon to set up their base of operations for astronomical observations to the west of Philadelphia. A reference point in the garden of the Harlan property, now known as Star Gazers' Stone, was placed to mark the astronomical meridian line north of their observatory.
Mason and Dixon used the finest astronomical instruments of their day in the survey, including a type of telescope, the zenith sector, used for measuring latitude and an "equal altitude and transit" instrument for sighting survey lines, as well as a less accurate quadrant for faster rough estimates of latitude, and a chronometer, used for measuring longitude. Though Harrison's chronometers later became the standard instrument for measuring longitude, the surveyors' job was mainly to measure latitude, and Mason preferred the lunar distance method of measuring longitude to the new method.
By February 28 1764 Mason and Dixon had determined the latitude at Star Gazers' Stone by observing the eight stars.
Although on private property, visitors are welcome. Visitors must start in the specified Cheslen Preserve parking area. Please then walk the marked trail around to the Star-Gazers' Stone.
Come (during the daylight hours only, please) to the spot where Mason and Dixon viewed the very stars that helped create the now famous Mason Dixon line, seperating the states of Pensylvania and Maryland.
To accomplish this cache, please answer the following questions via Geocache Messaging (please not email):
1. How far west is the Star-Gazers' Stone from Philadelphia? Why?
2. Behind the Star-Gazers' Stone, on the opposite side from the plaque, how many stones are visible in the bottom row of the stone enclosure? The top row?
3. Approximately how big is the top of the Star-Gazers' Stone itself? (Please do NOT enter the stone enclosure, just estimate)
4. Please post a picture with your log, either of you (optional) or your GPS near the Star-Gazer's Stone.
Congrats to TheAgent99 and bpp_picnic for their FTF... and to BethKatz for a close STF.
Sources: Star Gazers' Stone, by Doug, Quintessential Pennsylvania
Star Gazers' Stone, Wikipedia
Photo Credit: Mrs.Hoagie
Virtual Rewards 3.0 - 2022-2023
This Virtual Cache is part of a limited release of Virtuals created between March 1, 2022 and March 1, 2023. Only 4,000 cache owners were given the opportunity to hide a Virtual Cache. Learn more about Virtual Rewards 3.0 on the Geocaching Blog.