Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Karl Weissenberg (11 June 1893, Vienna 6 April 1976, The Hague) was an Austrian physicist, notable for his contributions to rheology and crystallography. The Weissenberg effect was named after him, as was the Weissenberg number. He invented a Goniometer to study X-ray diffraction of crystals for which he received the Duddell Medal of the Institute of Physics in 1946, and the Weissenberg rheogoniometer, a type of rheometer. The European Society of Rheology offers a Weissenberg award in his honour. He was born on 11 June 1893 in Vienna (Austria) and died in 1976 in the Netherlands.