A critical edition of Ibn al-Haytham's \textit{On the shape of the eclipse}. The first experimental study of the camera obscura
This book is much more than what is promised by the title. While the author refrains from a definite answer it is clear that he subscribes to the opinion that the mathematician/physicist al-Hasan Ibn al-Hasan Ibn al-Haytham is not identical with the philosopher Muhammad Ibn al-Hasan Ibn al Haytham. The book deals with the optics of an observation of a partial eclipse of the sun (identified as probably an eclipse in 990 observed in Basra) with a geometric-optics proof of the properties of the observed features (the variable image of the crescent-shaped sun). The critical edition of the Arabic text and its very legible English translation takes up about 50 pages of the 260 pages of the book. The extensive commentary first shows by a careful linguistic analysis that Ibn al-Haytham most probably was independent from precedessors and contemporaries in his mathematical treatment of geometric optics and also was misunderstood by modern commentators. The bulk of the commentary is a very detailed geometric exposition of the mathematics and physics referring to visibility and sharpness of the image observed in a camera obscura, including a study of he optimal size of the hole for sharpness. An appendix determines which manuscript illustrations seem to be authentic reproductions of the author's and which eclipse was observed. The author's idiosyncratic use of Arabic words to express scientific terms are collected in a useful glossary.
scientific article; zbMATH DE number 6644902