FRIEDRICH HASENOHRL 381 



We see that the connection between space, ether and 

 energy (to which matter also belongs), and gravitation, which 

 at present can only be stated in the form of suppositions or 

 questions, shows us to what extent we are surrounded by 

 the vast unknown, which has only been reduced but little 

 since the time of Pythagoras. But the fact that questions of 

 this kind can, thanks to Hasenohrl, be stated in so definite a 

 manner, as to lead to new ideas, means that we stand at the 

 beginning of further progress, which will occupy the great 

 men of science of the future, and will without doubt lead 

 to further surprises, inasmuch as nature will again speak to 

 us, and these surprises will perhaps be very unlike what we 

 now suppose, for this is what has happened in the course of 

 the centuries, through the work of the great men whom we 

 have considered. 



Friedrich Hasenohrl was born, like Boltzmann, in 

 Vienna. His father was a lawyer, his mother came of an old 

 military family. He first entered an aristocratic school, 

 later the Gymnasium, and then studied natural science and 

 mathematics at the university of his birthplace, particularly 

 as a pupil of Stefan and Boltzmann. Before the conclusion 

 of his university course he had already finished several 

 mathematical investigations, which earned him the warm 

 approbation of his teachers, and later also some experi- 

 mental work. He soon married, and became a privatdozent 

 in Vienna. After six years he became professor at the 

 Viennese Technical High School, and a little later Boltz- 

 mann's successor at the university. He was only able to 

 work there for eight years, under favourable circumstances. 



Then the war broke out, and Hasenohrl immediately 

 volunteered. He was everywhere at the front, first at the 

 defence of Przemysl, then in the Tyrolese mountains, which 

 he knew and greatly loved. After a bullet wound, which was 

 more or less healed, he again went to the front, and fell in 

 the second year of the war at Vielgereuth, only forty-one 



