Ewen-Purcell Horn Antenna
This horn antenna was used by Harold I. Ewen and Edward M. Purcell at the Lyman Laboratory of Physics at Harvard University in 1951 for the first detection of radio radiation from neutral atomic hydrogen gas in the Milky Way at a wavelength of 21 centimeters
Marker can be reached from West Virginia Route 28/92 east of Cemetery Road (County Route 28/25), on the right when traveling south.
Courtesy hmdb.org