This is another pocket park in the MetroWest Area of Boston. Chiswick Park was established with the sponsorship of Emerson Hospital (they have a clinic in the office park of the same name) and is a conservation area too. Benches have been provided along the walkway so that you can quietly sit and watch the local bird population.
The coordinates will bring you to a Chiswick Park entrance in an office/industrial area. There is also an entryway along Rt. 20 (Boston Post Rd.), opposite where Nobscot Rd. starts; park in the Middlesex Bank lot.
Once in the park, find the ring of stones. With the northernmost stone as #1 and counting clockwise, sit on stone #5 and sight across stone #3. Look for an object in the background. Using this sight line, walk 25 paces from stone #3. A camo lock-n-lock will be your reward.