Figure 1: Cover
The reasoning to use of electric magnetic waves to the locating of ships has been
registered of the engineer of Düsseldorf, Christian Hülsmeyer, already 1904 in
Germany and England as a patent.
One finds the illustration in the patent specification of a steamer which detects an approaching ship with help of the backscattering. Tests carried out on the Rhine river had in principle yielded the usefulness of this method.