242 Dr. T. Sterry Hunt on the 



tion of the latter only, according to him, belonging to phy- 

 siology *. 



On the other hand, we find well-known writers employing 

 the word physical and its congeners indifferently in their 

 wider and their more restricted meanings. Thus, in his 

 address before the British Association for the Advancement 

 of Science at Belfast, in 1874, Tyndall, in discussing the acti- 

 vities of the animal, speaks successively of " the work of the 

 physicist, . . . the comparative anatomist, and the physiolo- 

 gist." Following this, the influence of the nervous system 

 " over the whole organism, physical and mental," is spoken of • 

 and a few lines further on, " the physical life dealt with by 

 Mr. Darwin " is distinguished from " a psychical life ;" 

 while in the next paragraph we read of " organisms whose 

 vital actions are almost as purely physical " as the coalescence 

 of drops of oil suspended in a watery medium of the same 

 density in the classic experiments of Plateau f . In the first 

 citation the investigations by the dynamo-physicist of the 

 nervous and muscular activities of the animal are distinguished 

 from those of the biologist. In the second and third cita- 

 tions the physical organism and the physical life are distin- 

 guished, not as in the preceding, from the chemical and vital 

 (which they evidently include), but from the mental organi- 

 zation and the psychical life ; while in the fourth the anti- 

 thesis is between physical, in the sense of dynamical, on the 

 one hand, and chemical and vital processes on the other. 



§ 17. Thomson and Tait, in their treatise on Natural 

 Philosophy, wherein are considered only those simpler phe- 

 nomena of matter which are neither chemical nor vital, 

 employ the term Dynamics for the forces thus manifested, 

 and divide the study of them into Kinetics and Statics, or the 

 phenomena of actual motion and of rest. Some writers have 

 used static as the antithesis of dynamic (see further, § 24); 

 but statics, as implying simply equilibrium, are, as W. K. 

 Clifford has well remarked, " but a particular case of kine- 

 tics," and hence are to be included with the latter under the 

 common title of dynamics. Thomson and Tait consider under 

 this head, besides the phenomena of ordinary motion, the 

 vibrations which produce sound, and those motions by which 

 we seek to explain the phenomena of temperature/ radiant 

 energy, and electricity and magnetism. The whole of the 

 phenomena to which, in the modern and restricted sense, the 

 name of Physics is generally applied, are thereby included 



* "Relation of the Vital to the Physical Forces/' Philosophical Tran- 

 sactions, 1850, p. 727. 



t Tyndall's Belfast Address, Appleton's ed., pp. 50 & 51. 



