HERMANN LUDWIG FERDINAND HELMHOLTZ. 593 



Many cultivators of the biological sciences have been impressed with the 

 conviction that for an adequate study of their subject a thorough knowledge 

 of dynamical science is essential. But the manner in which some of them have 

 cut and pared at the facts in order to bring the phenomena within the range 

 of their dynamics, has tended to throw discredit on all attempts to apply 

 dynamical methods to biology. 



We purpose to make a few remarks on a portion of the scientific work 

 of Helmholtz, who is himself the most illustrious example not merely of ex- 

 tensive acquaintance with science combined with thoroughness, but of a thorough- 

 ness which of itself demands the mastery of many sciences, and in so doing 

 makes its mark on each. 



Hermann Ludwig Ferdinand Helmholtz was born August 31, 1821, at 

 Potsdam, where his father, Ferdinand Helmholtz, was Professor of the Gymnasium. 

 His mother, Caroline Penn, was of an emigrated English family. His father's 

 means would not admit of his studying science otherwise than as a medical 

 student. He therefore became a military surgeon, and continued in that posi- 

 tion till the end of 1848, when he was appointed Assistant of the Anatomical 

 Museum of Berlin, and Teacher of Anatomy at the Academy of Arts. In the 

 following year he went to Konigsberg, in Prussia, as Professor of Physiology. 

 In 1856 he became Professor of Anatomy and Physiology at the University of 

 Bonn; in 1859, Professor of Physiology at the University of Heidelberg; and, 

 in 1871, Professor of Natural Philosophy to the University of Berlin. 



It was during his career as a military surgeon that he published his cele- 

 brated essay on The Conservation of Energy. 



The science of dynamics has been so long established, that it is hardly 

 conceivable that any addition to its fundamental principles should yet remain 

 to be made. But in the application of pure dynamics to actual bodies a great 

 deal remains to be done. The great work for the men of science of the pre- 

 sent age is to extend our knowledge of the motion of matter from those 

 instances in which we can see and measure the motion to those in which our 

 senses are unable to trace it. For this purpose we must avail ourselves of 

 such principles of dynamics as are applicable to cases in which the precise 

 nature of the motion cannot be directly observed, and we must also discover 

 methods of observation by which effects which indicate the nature of the un- 

 seen motion may be measured. It is unnecessary here to refer to the labours 

 of the different men of science who, each in his own way, have contributed 



VOL. ll. 75 



