UMMBT 



PREFACE TO THE ENGLISH EDITION 



IN the historical record of science the name of Helm- 

 holtz stands unique in grandeur, as a master and leader 

 in mathematics, and in biology, and in physics. His 

 admirable theory of vortex rings is one of the most 

 beautiful of all the beautiful pieces of mathematical 

 work hitherto done in the dynamics of incompressible 

 fluids. In 1843, when he was only twenty-two years 

 old, and barely emerged from his undergraduate course 

 as a medical student, he showed, in his first published 

 scientific paper, a clear appreciation of the necessity 

 of distinguishing vital from non-vital phenomena : and 

 he gave experimental evidence tending to prove that 

 putrefaction and fermentation are essentially vital 

 actions : and thus led the way to Pasteur's splendid 

 and beneficent discoveries. His Erhaltung der Kraft, 

 published in 1847, was a guide to his own countrymen, 

 and to the rest of the world, in the doctrine of energy 

 through the whole range of dynamic action in dead 

 and living matter, then despised and rejected by nearly 

 all the high priests of science ; now cherished by all 

 as a most fruitful result of modern research. His 

 Tonempfindungen, and his Physiological Optics, are 

 not mere textbooks : they are ever memorable Prineipia 

 of the perception of sound, and of light, by living 

 creatures. 



