Originally, the Newtown Hosiery Mill, also known as the Stocking Works, operated out of this building at 301 South State Street. In 1884, John B. Mawson founded the Excelsior Bobbin and Spool Works in Yardley, and after a fire destroyed the Yardley plant in 1889, it moved to Newtown. In 1904, the Bobbin and Spool Works chartered the name Excelsior Bobbin and Spool Company and expanded with new buildings and updated equipment. After the brief tenure of the stocking manufacturer, the building was used by a stained glass company, a bobbin factory, and then during World War II by the Lavelle Aircraft Corporation. As wartime demand for aircraft surged, Lavelle expanded, and in July 1945 the company received the Army-Navy "E" for excellence in production at a ceremony held at the plant. After the war, the company shifted to stainless steel production for jet engines, missiles, and satellites. The world's first weather satellite, TIROS 1, was manufactured here in 1960 and recorded the first TV image from space. Some components used in the Apollo space missions were also manufactured here. In recent years, the property has been renovated into office space.