Seite - 24 - in Nikola Tesla and the Graz Tech

24 In the main subject ‘Applied electrical science’ (containing 243 pages), the following topics were dealt with: • Electrical telegraphy • Electric clocks • Electromagnetic motors • Electrotyping • Lightning conductor design • Ignition methods for exploding mines under water The documents from Josef Schaschl are testimony to the high academic level of Jakob Pöschl’s lecture. Building on fundamental explanations (using galvanic elements, and electrical measuring methods), electrical telegraphy (needle telegraphy, morse telegraphy) and electromagnetic motors (Gramme machines) were dealt with. Furthermore, there were expositions of contempo- raneous developments, such as the Atlantic cable and the then two-year-old telephone of Graham Bell. Nikola Tesla valued the lectures of Professor Jakob Pöschl very highly, receiv- ing an outstanding education in applied electrical science, which was definite- ly an extremely important basis for his later activities as an inventor. At the same time, he was often quite critical of the explanations of Jakob Pöschl. In the demonstration of a Gramme machine acting as a motor, sparks and loud noises were emitted from the brushes. Nikola Tesla asserted that it must be possible to actuate the motor without the brushes. Professor Pöschl coun- tered that this was not realistic, and concluded with a remark which can be found in Tesla’s autobiography as a quotation: ‘Herr Tesla may go on to achieve great things, but this will not be one of them. This would be as if a force act- ing in a straight direction, such as gravity, were to be converted into a force acting in a circular path. This would be comparable to a perpetuum mobile, an impossible idea.’