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The task which the author of this handbook has performed is a presentation of the art of communication by telephone as it is now practiced. To this end he describes the batteries, receivers, transmitters, signaling apparatus, and switch boards in general use, the systems employed in operating telephone exchanges, modes of constructing telephone lines, together with the poles, wires, insulators, and other material required in the construction. Long-distance working is also treated, and underground work and the localization of faults are not omitted, while a few minor or very recent topics are included in a miscellaneous chapter and an appendix. The volume is a thoroughly practical one and is fully illustrated.

author has dealt most largely in this work on facts gleaned from his own experience, while he has aimed to touch upon theoretical questions only when it was essential for the understanding of practical facts. Much attention has been given to matters of cost, both of construction and subsequent operation, and in this expenses are given, not as calculated on paper, but as actually incurred in building on a large scale and in smelting many thousand tons of ores under various circumstances, and in all the ordinary kinds of furnaces. The first edition of the book was published in 1887. For the second edition such new material as time and experience have suggested has been added. But the advances in copper smelting since the work first appeared have been rather in a general enlargement of furnaces and apparatus than in any radical changes or inventions. A section on the electrolytic assay of copper has been prepared by Mr. Francis L. Sperry, of Sudbury, Ontario, and information and plans of the regenerative gas-furnaces used at Atvidaberg, Sweden, have been furnished by Mr. Paul Johnson. It is in these regenerative gas-furnaces that the author expects to see realized the vital point of economy in the use of fuel. In the first chapter the ores of copper are described; in the second, their distribution is pointed out. The chapters that follow concern methods of copper assaying, the roasting of copper ores in lump form, stall roasting, roasting in lump form in kilns, calcination of ore and matte in a finely divided condition, the chemistry of the calcining process, smelting, blast-furnaces, the smelting of pyritous ores containing copper and nickel, reverberatory furnaces, refinement of copper with gas in Sweden, treatment of gold and silver bearing copper ores, and the Bessemerizing of copper mattes.

second installment of this course of study consists wholly of experiments, most of them being in the domain of physics, but some in that of chemistry. The elementary laws and principles of mechanics, acoustics, optics, and electricity are successively brought out, and a few forms of chemical action are illustrated. A list of questions is given on the work included in each chapter. This part of the course is designed for young students, hence the directions and interpretations of the experiments are given in simple language. An appendix contains hints for performing the experiments, and there are sixty diagrams of apparatus in the body of the book. The author states that he has throughout aimed at rendering the experiments feasible with a very limited apparatus, and inexpensive materials and appliances.

objects of this little book are to explain the commonly accepted theory in regard to the action of electricity, and to describe the various ways in which electrical energy has been practically utilized. The theoretical part of the subject most needs explanation, and hence naturally receives most attention. Among the practical questions of popular interest that are answered are. How long does it take to send a signal