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Rh of four principal parts, in the first of which the author considers the sources of electricity—hydro-and thermo-electric batteries and machines—and also various apparatus for transforming currents, under which heading he places accumulators or secondary batteries. The second part is devoted to electric lamps—regulators, candles, and those producing light by incandescence. In the third division the subject of telephones and microphones is taken up, and all the later forms of these pieces of apparatus are described. In the fourth and final part there are considered various applications of electricity, such as devices for indicating fire-damp in coal-mines, fire-alarms, etc., the electrical transmissional power, electro-motors, and electric distribution.

While the book will be found in many respects an excellent popular résumé of the subject, it is not without defects, and lacks the completeness which a work of this character should at the present time possess. The daily as well as the technical press has familiarized most persons interested in the subject with the various types of lamps which have so far been developed, and the questions of interest now are mainly those of cost and the conditions upon which electric lighting in general depends. Much of the description of different forms of lamps of the same class might, therefore, have been dispensed with—such, for instance, as the various forms of candles and the lamps of imperfect contact, neither of which promise to have much of a future before them—and been given with advantage to incandescent lamps employing a carbon filament. The treatment of this class of lamps is, to say the least, meager, and that of the workers in this field far from satisfactory. One would hardly get a correct idea of the relation of Mr. Edison's work to the present successful results by the author's presentation of it. The treatment of the problem of distribution is hardly as full and complete as might be desired, or the work of M. Marcel Deprez in this direction as clear and as full as it should be. The work on the whole is, however, a very readable one, and will give those unacquainted with the recent advances in the industrial applications of electricity a fairly good idea of what has been so far accomplished.

work may be regarded as in certain senses a pioneer in the field of literature to which it relates. The aim of the author has been to furnish students with materials for a more scientific study of English etymology than is commonly to be found in previous works on the subject. The older dictionaries were rich in quotations illustrative of the words they defined, but their etymologies were defective and of the crudest kind, being in most cases thoroughly unscientific guess-work, and most likely wrong. In many instances, Mr. Skeat says, he has found evidence that the dictionary-makers manufactured words for the express purpose of deriving others from them. The earlier editions of Webster's "Dictionary" gave the corresponding words and the one under consideration from a great number of languages, without any discrimination based upon the possibility of their having or not having a real relation with the English word. Such comparison was, perhaps, interesting as a curiosity, but was confusing to etymological students, and could give no clew to the derivation of the word. Better work has been done in the later editions of Webster, in which Dr. Mahn's etymologies deserve and receive commendation; but the plan of the work, says Mr. Skeat, "does not allow of much explanation of a purely philological character." In preparing his work the author has been guided by certain canons, a few of which, such as commend themselves to the general reader, are: Before attempting an etymology, ascertain the earliest form and use of the word, and observe chronology, observe history and geography, observe phonetic laws. The whole of a word, and not a portion only, ought to be reasonably accounted for; mere resemblance of form, and apparent connection in sense between languages which have different phonetic laws, or no necessary connection, are commonly a delusion, and are not to be regarded; and it is useless to offer an explanation of an English word which will not also explain all the cognate forms. The attempt is made to give the exact history of