650 INDEX OF SUBJECTS. 



PART IV. ELECTROMAGNETISM. 

 CHAPTER I. CURRENTS AND MAGNETIC SHELLS. 



PAGE 



CErsted's Experiment 420 



Magnetic Field of a Current 420 



Action of a Rectilinear Current on a Pole. Experiments of Biot and Savart 421 



Potential of an Unlimited Rectilinear Current 423 



The Potential of an Unlimited Current is not a Simple Function of the 



Co-ordinates 425 



Potential of an Angular Current 426 



Potential of a Triangular Current 427 



Potential of any Closed Circuit 428 



Equivalence of a Closed Current and of a Magnetic Shell. Ampere's Theorem 428 

 Remarks on the Equivalence of a Closed Current and a Magnetic Shell . . 429 



Relative Energy of a Magnetic System and a Current 430 



Reciprocal Action of Two Closed Currents 432 



Relative Energy of Two Currents 432 



Electromagnetic Rotation 433 



Faraday's Experiments 434 



Another Form of Expression for the Electromagnetic Work 436 



Electromagnetic Action on a Current-Element 437 



Reciprocal Action of Two Elements of a Current 438 



Electromagnetic Intensity of a Current 438 



Electromagnetic Units 439 



CHAPTER II. ELEMENTARY ACTIONS. 



Ampere's Method 440 



Action of a Pole on a Current Element. Fundamental Principles . . . 441 



Reciprocal Action of a Pole and of a Current 446 



Equivalence of a Current and a Magnetic Shell 449 



Action of Two Elements of a Current 449 



Determination of the Functions Y(r) and f(r) 452 



Determination of the Ratio of the Two Constants 454 



Determination of the Constant h 456 



Electrodynamic Unit of Intensity 459 



Formulae Equivalent to that of Ampere 460 



Formula of M. Reynard 460 



General Formula 462 



Ampere's Formula 463 



Grassmann's Formula 463 



