Career
He worked as a structural engineer for the Loodswezen, the Dutch organization overseeing all maritime pilots. Harder"s lighthouses were made of cast iron, a new material at the time, which allowed for segmented fabrication and construction. Eierland Lighthouse (Texel, 1864)
Nieuwe Sluis (1867)
Scheveningen Lighthouse (1875)
Short lighthouse of Westkapelle (1875)
Lange Jaap (Den Helder, 1877-1878)
Lage vuurtoren van IJmuiden (1878)
Hoge vuurtoren van IJmuiden (1878)
Bornrif (Ameland, 1880-1881)
Den Oever Lighthouse (1884)
Stavoren Lighthouse (1884)
Vuurduin (Vlieland, 1909).