A pioneer in the field of astrophysics, Johann Zollner (1834 1882) was a professor of physics and astronomy at the University of Leipzig and an associate of the Royal Astronomical Society. Zollner was best known for his work on astronomical photometry and spectrum analysis, on which he published widely. He invented the astronomical photometer used for measuring stellar magnitudes. He was also interested in optical illusions: the 'Zollner illusion' consists of straight parallel lines which appear to be unparallel. This book, published in German in 1878 1879 and translated into English by...