xii CONTENTS OF VOL. I. 



of the hydraulic accumulator — Perpetual motion : in what sense impossible — 

 Faraday's question, as to the law of conservation — Answer — Faraday's question 

 as to gravity and electricity — Answer — Controversy as to tlie measure of Force 

 — Energy of motion and momentum— Their difference illustrated. Pp, 16 — 24 



CHAPTER n. 



TEANSFORMATIOXS OF ENERGY. 



Energy of motion, and heat, are measurable by quantity — Measure of heat- 

 Dynamical equivalent of heat— Heat is molecular motion — All matter is per- 

 fectly elastic — Motion transformed into electricity — Quantitative equivalence 

 of all forms of energy— Radiation of heat — Radiant heat, light, and the actinic 

 rays classed together as radiance — Absorption of radiance — Heating power of 

 moonbeams — Transformation of motion into heat, and the converse : motion 

 into electricity, and the converse : electricity into heat, and the converse : 

 heat into radiance, and the converse — No exception to the rea^jpearance of the 

 energy that has done work — Forces that cannot produce energy — Measiire of 

 strength Pp. 25—31 



CHAPTER III. 



STATIC AND KINETIC ENEKGY. 



Primary forces —Electric and magnetic forces not primary — Static and kinetic 

 energy — Strained elasticity — Vibrating strings — Transformations of static 

 energy. 



Note : Electric and Magnetic Energy : — Electro-dynamic induction — Experiment 

 I. — Experiment II. : Explanation — Experiment III. — Expeiiment IV.: Ex- 

 planation — Electro-static induction, and continuous currents, probably both 

 due to molecular tension — Electro-magnetic induction — Experiment V. — Ex- 

 periment VI. : Explanation — Experiments VII. and VIII.- — Experiment IX. : 

 Elongation of iron bar during magnetisation — Expeiiment X. — Sounds produced 

 by magnetisation — The magneto-electric machine transforms mechanical into 

 electric energy Pp. 32 — 38 



CHAPTER IV. 



PRIMARY FORCES. 



Force originates energy, but energy cannot originate primary forces — Primarj' 

 forces defined — Instances of forces not primary — Three primary forces, gi-avity, 

 capUlarity, and affinity — Their properties — Summary of their jiroperties — AH 

 primaiy forces are attractive — Purpose of this — Potential energy is a joint 

 function of two mutually attracting bodies — No distinction between combus- 

 tibles and supporters of combustion — Forces belong to the original constitution 

 of matter — Theory of Descartes disproved — Matter may have none but dyna- 

 mical properties — Maj' not be extended, and not impenetrable . Pp. 39 — 46 



