He also invented the Pfund telescope, which is a method for achieving a fixed telescope focal point regardless of where the telescope line of sight is positioned, and the Pfund sky compass, which arose from Pfund's studies of the polarization of scattered light from the sky in 1944, and which greatly helped transpolar flights by allowing the determination of the Sun's direction in twilight.
U.S. Route 66 | U.S. Route 1 | U.S. Route 6 | U.S. Route 101 | Route 66 | U.S. Route 30 | Order of the Polar Star | New Jersey Route 4 | European route E65 | U.S. Route 40 | California State Route 1 | U.S. Route 1 in Maine | Pennsylvania Route 309 | European route E18 | U.S. Route 23 | European route E4 | U.S. Route 9 in New York | U.S. Route 11 | Pennsylvania Route 82 | European route E70 | U.S. Route 90 | U.S. Route 75 | U.S. Route 61 | U.S. Route 60 | Pennsylvania Route 73 | New York State Route 32 | European route E55 | U.S. Route 80 | U.S. Route 71 | U.S. Route 51 |