EDITOR'S PREFACE.
A SUFFICIENT reason for republishing an English translation of the wonderful book of Professor G. S. Ohm is the difficulty with which the only previous translation (that of Taylor's Scientific Memoirs) is procurable.
Besides this, however, the intrinsic value of the book is so great, that it should be read by all electricians who care for more than superficial knowledge.
It is most remarkable to note at this time, how completely Ohm has investigated the subject, and how far in advance of his age he was.
It is well said by Chrystal, in his great Encyclopædia Britannica article on Electricity, that "Ohm rendered a great service to the science of electricity by publishing his mathematical theory of the galvanic circuit." Before his time, the quantitative circumstances of the electric current had been indicated, in a vague way, by the use of the terms "intensity" and "quantity," to which no accurately defined meaning was attached. Ohm's service consisted in introducing and defining the
3
