_JOHN MACLEAN_, Professor of Natural Philosophy and Chemistry in the College of New-Jersey. Nassau Hall, Oct. 20, 1809. _The Epitome of Electricity appears to me to contain a concise, but perspicuous and correct statement of the laws of that branch of Philosophy, and an interesting collection of facts and experiments, by which they are illustrated._ _JEREMIAH DAY_, Professor of Mathematics and Natural Philosophy. Yale College, Nov. 25, 1809. [As the authors could not transmit to Professor DAY a copy of the Epitome of Galvanism, without unduly delaying the publication, his testimonial, of course, refers only to the Epitome of Electricity.] PREFACE. Having denominated the following work an epitome of Electricity and Galvanism, it seems reasonable to request that the reader should keep the nature of our plan in view. If the book do not contain, on the subjects proposed to be treated, all that is most important, let it be condemned. But let not detail be expected where the design requires conciseness. There are some articles under which we were obliged, either to omit unimportant improvements, or to occupy several pages in describing them. Where, however, omissions of any consequence have taken place, we have endeavoured carefully to refer to the books which will supply them; so that our work may not only teach the elements and substance of the science, but direct those who wish to pursue it most extensively—We particularly regretted that we could not describe a variety of electrometers. Short as our work is, we found it, notwithstanding, scarcely practicable to avoid some repetition. In a few instances the historical and scientific parts may be observed, in a small degree, to interfere. Where history was useful to illustrate experiment, or experiment composed a part of history, we did not choose to separate what perspicuity required to be kept together. We hope, on the whole, that we do not need more indulgence in this respect, than we shall readily find, from those who are fond of the subjects which it was our business and our pleasure to investigate.