USGS Tower on Mount GuyotGreat Smoky Mountains National ParkOriginal Captions: In mapping the mountains, the USGS built towers on tops of various peaks. An automobile battery was used to light a light on the towers at night. USGS surveyors at the Andrew Johnson Hotel in Knoxville would take readings on the lights. USGS Tower on Mt. Guyot; III-S-16970, History - Historic Sites .In mapping the mountains, the USGS built towers on tops of various peaks. An automobile battery was used to light a light on the towers at night. USGS surveyors at the Andrew Johnson Hotel in Knoxville would take readings on the lights.USGS Tower on Mt. Guyot, III-S-16970, History - Historic Sites