By GEORGE M. HOPKINS

Revised and Greatly Enlarged Two Octavo Volumes

1,000 Pages 900 Illustrations

Cloth Bound, Postpaid, $5.00 Half Morocco, Postpaid, $7.00

Or Volumes Sold Separately: Cloth, $3.00 per Volume Half Morocco, $4.00

Experimental Science is so well known to many of our readers that it is hardly necessary now to give a description of this work. Mr. Hopkins decided some sime ago that it would be necessary to prepare a new edition of this work in order that the many wonderful discoveries of modern times might be fully described in its pages. Since the last edition was published, wonderful developments in wireless telegraphy, for example, have been made. It was necessary, therefore, that a good deal of new matter should be added to the work in order to make it thoroughly up-to-date, and with this object in view some 260 pages have been added. On account of the increased size of the work it has been necessary to divide it into two volumes, handsomely bound in buckram. It may be interesting to note the following additions that have been made to these volumes:

Volume I contains in addition to a large number of simple, well illustrated experiments, a full description of a 1/4 H. P. electric motor made expressly for illustration in this edition of "Experimental Science." It is an enclosed self-regulating electric motor for a 110 volt circuit. It can be operated by a current from a 1 10 volt lamp socket, yielding a full 1/4 H. P., or it may be used as a dynamo, furnishing a current capable of operating three 16-candle-power, 110 volt incandescent lamps. The construction of the machine is perfect enough to admit of enlarging or reducing its size if desired.

Volume II contains much on the general subject of electricity, besides new articles of great importance. Among these the subject of alternate current machinery is treated. Wireless Telegraphy and Telephony receive attention. Electrical Measuring Instruments, The Electric Clock, The Tele-graphone, Experiments in High Voltage, The Nernst Lamp, and Measuring the Heat of the Stars are all thoroughly illustrated and described.

The unprecedented sale of this work shows conclusively that it is the book of the age for teachers, students, experimenters and all others who desire a general knowledge of Physics or Natural Philosophy.

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