Book contents
- Frontmatter
- PREFACE
- Contents
- PART I THE UNKNOWABLE
- PART II LAWS OF THE KNOWABLE
- I LAWS IN GENERAL
- II THE LAW OF EVOLUTION
- III THE LAW OF EVOLUTION (CONTINUED)
- IV THE CAUSES OF EVOLUTION
- V SPACE, TIME, MATTER, MOTION, AND FORCE
- VI THE INDESTRUCTIBILITY OF MATTER
- VII THE CONTINUITY OF MOTION
- VIII THE PERSISTENCE OF FORCE
- IX THE CORRELATION AND EQUIVALENCE OF FORCES
- X THE DIRECTION OF MOTION
- XI THE RHYTHM OF MOTION
- XII THE CONDITIONS ESSENTIAL TO EVOLUTION
- XIII THE INSTABILITY OF THE HOMOGENEOUS
- XIV THE MULTIPLICATION OF EFFECTS
- XV DIFFERENTIATION AND INTEGRATION
- XVI EQUILIBRATION
IX - THE CORRELATION AND EQUIVALENCE OF FORCES
Published online by Cambridge University Press: 29 August 2010
- Frontmatter
- PREFACE
- Contents
- PART I THE UNKNOWABLE
- PART II LAWS OF THE KNOWABLE
- I LAWS IN GENERAL
- II THE LAW OF EVOLUTION
- III THE LAW OF EVOLUTION (CONTINUED)
- IV THE CAUSES OF EVOLUTION
- V SPACE, TIME, MATTER, MOTION, AND FORCE
- VI THE INDESTRUCTIBILITY OF MATTER
- VII THE CONTINUITY OF MOTION
- VIII THE PERSISTENCE OF FORCE
- IX THE CORRELATION AND EQUIVALENCE OF FORCES
- X THE DIRECTION OF MOTION
- XI THE RHYTHM OF MOTION
- XII THE CONDITIONS ESSENTIAL TO EVOLUTION
- XIII THE INSTABILITY OF THE HOMOGENEOUS
- XIV THE MULTIPLICATION OF EFFECTS
- XV DIFFERENTIATION AND INTEGRATION
- XVI EQUILIBRATION
Summary
§ 77. When, to the unaided senses, Science began to add supplementary senses in the shape of measuring instruments, men began to perceive various phenomena which eyes and fingers could not distinguish. Of known forms of force, minuter manifestations became appreciable; and forms of force before unknown were rendered cognizable and measureable. Where forces had apparently ended in nothing, and had been carelessly supposed to have actually done so, instrumental observation proved that effects had in every instance been produced: the forces reappearing in new shapes. Hence there has at length arisen the inquiry whether the force displayed in each surrounding change, does not in the act of expenditure undergo metamorphosis into an equivalent amount of some other force or forces. And to this inquiry experiment is giving an affirmative answer, which becomes day by day more decisive. Grove, Helmholtz, and Meyer, are more than any others to be credited with the clear enunciation of this doctrine. Let us glance at the evidence on which it rests.
Motion, wherever we can directly trace its genesis, we find to pre-exist as some other mode of force. Our own voluntary acts have always certain sensations of muscular tension as their antecedents. When, as in letting fall a relaxed limb, we are conscious of a bodily movement requiring no effort, the explanation is that the effort was exerted in raising the limb to the position whence it fell.
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- First Principles , pp. 259 - 285Publisher: Cambridge University PressPrint publication year: 2009First published in: 1862