RECAPITULATION. 143 



14. The Law and Rate of the Expansion 

 of Air by Heat. 



15. The Quantity of Heat absorbed in the 

 Expansion of Air. 



16. The Law and Rate of the Passage of 

 Aqueous Vapour through Air. 



17. The Laws of Electricity ; its relations 

 to Air and Moisture. 



18. The Fluidity, Density, and Elasticity 

 of the Air, by means of which its vibrations 

 produce Sound. 



19. The Fluidity, Density, and Elasticity 

 of the Ether, by means of which its vibrations 

 produce light. 



2. These are the data, the elements, as astrono- 

 mers call the quantities which determine a planet's 

 orbit, on which the mere inorganic part of the 

 universe is constructed. To these, the constitu- 

 tion of the organic world is adapted in innumerable 

 points, by laws of which we can trace the results, 

 though we cannot analyze their machinery. 

 Thus, the vital functions of vegetables have 

 periods which correspond to the length of the 

 year, and of the day ; their vital powers have 

 forces which correspond to the force of gravity ; 

 the sentient faculties of man are such that the 

 vibrations of air, (within certain limits,) are per- 

 ceived as sound, those of ether, as light. And 

 while we are enumerating these correspondencies, 



