CHAPTER III

PRINCIPLES

§ 1. The Principles of Physics: The Principles of
Mechanics affected by recent discoveries--Is mass
indestructible?--Landolt and Heydweiller's experiments
--Lavoisier's law only approximately true--Curie's
principle of symmetry.

§ 2. The Principle of the Conservation of Energy:
Its evolution: Bernoulli, Lavoisier and Laplace, Young,
Rumford, Davy, Sadi Carnot, and Robert Mayer--Mayer's
drawbacks--Error of those who would make mechanics part
of energetics--Verdet's predictions--Rankine inventor
of energetics--Usefulness of Work as standard form of
energy--Physicists who think matter form of energy--
Objections to this--Philosophical value of conservation
doctrine.

§ 3. The Principle of Carnot and Clausius:
Originality of Carnot's principle that fall of
temperature necessary for production of work by heat--
Clausius' postulate that heat cannot pass from cold to
hot body without accessory phenomena--Entropy result
of this--Definition of entropy--Entropy tends to increase
incessantly--A magnitude which measures evolution
of system--Clausius' and Kelvin's deduction that
heat end of all energy in Universe--Objection to this--
Carnot's principle not necessarily referable to mechanics