A History of Early Optical Oceanographic Instrument Design in Scandinavia

Interest in the optical characteristics and variability of the sea has grown for nearly two centuries. Most of the early work in this area was performed by European investigators. Perhaps the earliest reference to an optical oceanographic research cruise can be found in the book by Otto Krümmel (1886), in which the author refers to the Rurik circumnavigational cruise of 1817 made by Otto von Kotzebue. In these studies von Kotzebue made measurements using optical instrumentation comprised of a piece of red cloth tethered to a line and lowered into the sea. With this technique, von Kotzebue was able to crudely measure the depth of penetration of light. This technique was refined by using a white plate, and the first measurements in the Pacific (at 10°N 152°W) yielded measurements of 49 meters. It is worth noting that this work was done several decades before the famous efforts of Secchi (1866). Efforts to incorporate photographic techniques to characterize the underwater light field were also developing in the late 1800’s. In March, 1885 some experiments were made in the waters off Nice, France, in which a photographic plate was submerged to depths of several hundred meters. Additional historical information can be found in the classical textbook by Sauberer and Ruttner (1941). Theoretical treatments of optical oceanography developed somewhat later. Ludvig Valentin Lorenz published the first works on the theoretical aspects of marine light scattering. This work, originally published in Danish (Lorenz, 1890), was subsequently translated into French in 1915. Martin Knudsen (founder of International Council for the Exploration of the Sea, and developer of some of the fundamental concepts for making hydrographic calculations) also had concerns about marine optics as reflected in correspondence he sent to Professor Otto Pettersson (father of Hans Pettersson) in Sweden: . . . In studying those provinces of water and particularly of sea water, which are of importance to the organisms living therein, the study of the light contents of the water must occupy the prominent place. Light contents play in many respects a similar part to that of oxygen content but have not been so strongly investigated as the latter. . . .