HERMANN VON HELMHOLTZ. 717 



If, however, instead of coiitemplatiug the final results we consider 

 what is actnally going- on at a given instant at a given place it is 

 possible to describe the facts in simple terms. A minute sphere of 

 the liquid may be moving as a whole in some definite direction, may 

 be changing its shape, and may be rotating about an axis. This last 

 is the distinguishing characteristic of vortex motion. You Helmholtz 

 was the first to detect some of the most remarkable properties of those 

 portions of a fluid in which it occurs. The investigation was confined 

 to a frictionless, incompressible liquid, and the author proved that in 

 such an ideal substance the property of vortex motion could neither be 

 ])roduced nor destroyed by any natural forces. If it existed in a group 

 of particles, they would be incai)able of transmitting it to others. 

 They could not be deprived of it themselves. The laws of their motion 

 would establish between them a curious and indissoluble fellowship. 



A number of beads, strung on a ring of thread or wire and I'otat- 

 ing about it, afford, with regard to a similarly shaped system of par- 

 ticles possessing vortex motion, an analogy so imperfect that it is 

 almost dangerous to use it. But the two have, at all events, one prop- 

 erty in common. The wire may be moved from place to place or bent 

 into various forms, but wherever it goes, however it is distorted, it 

 carries the beads with it. The connection thus artificially secured 

 would be automatically maintained in a ring of fluid particles endowed 

 Avith vortex motion. The ring might enlarge or contract, be deflected 

 or distorted, but amid all such vicissitudes the rotating particles 

 would move among their fellows apparently free, but in reality insep- 

 arably united. 



This and other iteculiarities, upon which it is unnecessary to dwell, 

 give to vortex motion a special interest and importance. Lord Kelvin 

 has made the protbund and remarkal)le suggestion that the atoms of 

 matter may be vortex rings in a frictionless liquid. Whatever the 

 ultimate fate of this theory may be, it is justified as affording a glimpse 

 into new possibilities. It is, at all events, not absurd to dream that 

 we may some day regard matter as a special form of S(une more funda- 

 mental substance, from the comi)aratively simple properties of which 

 the laws of chemistry and j^hysics may be deduced. Apart, however, 

 from the use which has been made of vortexes in this and lu other 

 ways, as affording a basis for the explanation of physical facts, Von 

 Helmholtz must rank as the discoverer of a series of fundamental 

 propositions in hydrodynamics which had entirely escaped the notice 

 of his predecessors. 



During the last years of his life Von Helmholtz was president of the 

 " Physikalisch Teclmische Eeichsaustalt" at Charlottenberg. In 1884 

 the late Werner Siemens offered £25,000 toward the foundation of a 

 State research laboratory. The Iveichstag voted the necessary addi- 

 tions to this sum. The institution has been established on a large scale, 

 and the first volume of records was juiblished in March of the present 



