522 THE GRAMMAR OF SCIENCE 



The last branch of the Precise Physical Sciences is 

 termed the Physics of the Ether, and deals with the rela- 

 tive motions of ether-elements, or the changes of shape 

 we attribute to the ether (p. 262). If we consider the 

 ether, apart from the molecules we suppose it to contain, 

 merely as a medium transmitting various kinds of motions, 

 we have the Theory of Radiation, which describes how 

 light, heat, and electro-magnetic effects are conceived to 

 be propagated from molecule to molecule. If we deal 

 with the mutual action between ether and molecule (pp. 

 279, 311)) "^"^^ describe how molecules disperse, absorb, 

 transmit, or conduct optical, thermal, or electro-magnetic 

 effects, we have the remaining portions of the funda- 

 mental physical sciences of Light, Heat, Electricity, and 

 Magnetism. 



From the Synoptic Physical Sciences we demand a 

 rational classification of those physical phenomena which 

 have not at present been conceptualised by simple for- 

 mulae of motion. Such phenomena we should naturally 

 expect to find where in ordinary parlance there are " a 

 great number of forces contemporaneously at work," or 

 where, in more accurate language, the number of element- 

 ary bodies by which we should have to conceptualise the 

 phenomena is so great that we are at present unable by 

 synthesis (p. 236) to form the complex motion, which 

 would describe the changes of the whole system. This is 

 particularly the case in the sciences which deal with the 

 evolution and structure of great and intricate bodies like 

 a planetary system or a planet itself. We desire to know 

 the sequence of changes by which we can describe the 

 evolution of a planetary system and we seek an answer 

 in the Nebular Theory. We desire to know how the 

 inorganic structure of our Earth has developed, — Geology 

 describes it. Then we turn to the formation of the sur- 

 face of the Earth, and to the continual changes going on 

 among the gases and fluids there, and study Physical 

 Geography and Meteorology. 



Finally, we inquire into the structure of the substances 

 which form our environment and their relations to each 



