Survey calibration baselines are used by geodesists and surveyors in their important work. One, called the Sand Point calibration baseline, runs right through magnificent Magnuson Park. There are about a dozen such baselines in Washington, but the Sand Point line is perhaps the most used in the state. The accuracy of the Sand Point line is said to be within half a millimeter.
To highlight this “invisible” line, in 2007 Seattle artist Perri Lynch erected a string of twelve 6-foot-high limestone columns through the park; these columns are aligned precisely with each other along the Sand Point calibration baseline.
The installation is called "Straight Shot," and features peepholes bored through each column, allowing people to experience what a surveyor does. The cache is placed near one of these awesome monoliths in the park.
There is also a benchmark nearby that you can log if you are interested.
No need to leave the trail to retrieve the cache. Park hours are from 4 a.m. to 11 p.m.
Congratulations to shrek98 on the FTF on his birthday, January 26, 2012!