AN INTRODUCTION TO THE THEORY OF ELECTRICITY WITH NUMEROUS EXAMPLES BY LINNÆUS CUMMING, M.A., LATE SCHOLAR OF TRINITY COLLEGE, CAMBRIDGE, THIRD EDITION WITH CORRECTIONS AND ADDITIONS London: MACMILLAN AND CO. 1885 [The Right of Translation is reserved.] PREFACE TO THE FIRST EDITION. THE present work has grown out of an attempt, while giving my Cheltenham pupils the experimental details of electricity, to impart at the same time to the more intelligent among them consistent though elementary ideas of the theory which underlies the experiments. At the instance of friends interested in scientific teaching, I undertook to prepare from the notes I had used for my class the work which now issues from the press. Among such friends I must specially refer to my former colleague, Dr J. A. Fleming, who rendered me considerable assistance in arranging the plan of the earlier portions of the work. Geometrical as distinguished from analytical methods have been employed, and although a large proportion of the propositions involve the ideas of the Doctrine of Limits, the use of the notation of the Calculus has been avoided. A competent knowledge of Calculus is rare among schoolboys, and experience as a teacher has shewn that a geometrical investigation often gives a grasp of the method where an analytical one would give only the result. The foundation of the method employed is really the conception of Lines of Force, so largely used by Faraday in his researches as a means of exhibiting without mathematical symbols the quantitative relations of a field of force; relations, which assume at once a numerical expression by help of Prof. Stokes' beautiful theorem given in the 5th and 6th Propositions of the second Chapter. I must take this opportunity of acknowledging the debt I (in common with all modern students of Electricity) owe to the writings of Sir W. Thomson, Prof. Clerk Maxwell, and M. Wiedemann, which I have consulted at every step. In addition to these, I have derived profit from a large number of miscellaneous papers. References to results obtained from these may have through oversight been omitted, and for such omissions I must crave indulgence. 918267 |