The Electrotherm The Electrical Substitute for Hot Water Bottle The Electrotherm is of the greatest convenience in the relief of General Chilliness, Cold Feet, Cramps and other local pains. Its value and efficiency is unequaled in cases of Pneumonia, Rheumatism, Neuralgia, Bronchial Affections, Croup, Bowel Complaints, Sluggish Circulation, and wherever the local application of artificial heat is desired. When the effect of a poultice or moist heat is desired, it should be applied over one or two thicknesses of damp flannel. The pad can be safely used by any one. 1. Is light and flexible. 2. Warms up gradually to any desired temperature, thus allowing the use of higher temperatures than is possible where applied suddenly. 3. Remains at a uniform temperature for any length of time, subject to regulation without disturbing patient in any manner; thus enabling the heat to penetrate deeper into the affected part, increasing its efficacy. 4. Is provided with a sensitive thermostat incorporated in the pad which acts automatically to limit the temperature from exceeding a desired or safe degree, thus guarding against the possibility of over heating. 5. Requires practically no attention, The size of the Electrotherm for general use is 11 x 15 inches, 4 inch thick. It is provided with regulating switch, connecting plug and 15 feet of flexible conducting cord, with coverings suited to various purposes. The pads require no more current than a 16 candle-power incandescent lamp; one-half ampere at 110 volts or one ampere at 50 volts. They can be connected to any electric light fixture. The cost of maintaining a constant heat with this pad does not exceed one cent per hour. State Voltage when ordering. Price, $6.50. Home Medical Battery For Physician or Patient, Home use or Traveling, this is the best and most convenient form of Medical Battery ever produced. Its currents are smooth and even, and their strength can be graded from the mildest perceptible to a power that few can endure. The complete battery is contained in an elegant, highly polished Mahogany case, having a strong, handy, nickelplated handle. The dimensions of the case are 9 x 54 x 4% inches, and its weight complete with Cell and Electrodes is about 5% pounds. The Standard Dry Battery, which is used with this apparatus, being a staple commercial article made only in one size and shape, is easily obtainable at any Electrical Supply store. One cell will last from 4 to 12 months, according to the length and frequency of applications. The unusually complete and excellent set of Electrodes furnished with this instrument makes it very convenient in a great variety of applications for the patient with or without assistance. The W. G. Nagel Electric Company 520 Adams Street, Toledo, Ohio Main Building, Armour Institute of Technology Preparation for College BY MAIL Instruction under the direction of the regular teachers in a resident engineering college. Lessons prepared especially for home study by teachers of acknowledged standing. The full College Preparatory Course covers the entrance requirements of such a college as ARMOUR INSTITUTE OF TECHNOLOGY, and students satisfactorily completing this course are admitted to the college of engineering of that institution without further examination in the subjects taken. An unusual opportunity for young men of limited means to prepare for entrance to an engineering college without leaving home or interfering with their regular work. PARENTS wishing to KEEP THEIR This is an excellent opportunity for teachers and others to take up engineering studies in their own homes and at their own convenience under the guidance of resident school teachers. In addition to the College Preparatory Course I instruction is also offered in Mathematics (Arithmetic, Algebra, Geom- 200 page illustrated Bulletin, giving full information as to courses, teachers, methods of study, etc., may be had upon request. American School of Correspondence at Armour Institute of Technology CHICAGO, ILL., U. S. A. Mention The Technical World, Jan. LITERATURE EVIEWS MAGAZINES BOOKS RECEIVED Alternating-Current Engineering. By E. B. Raymond, Testing Department, General Electric Company. Cloth, 102 Illustrations. Pages 342. D. Van Nostrand Company, New York City, Publishers. Price $2.50. IN VIEW of the ever-increasing importance of alternating currents and alternating-current apparatus, and the rapidity with which the latter is replacing directcurrent machinery, it is necessary that every electrical man should be familiar with this subject. This book, therefore, has considerable value at this particular time, treating the subject, as it does, in an extremely practical manner, while dealing only with matters which bear directly on engineering work. No calculus is used in the book. The work begins by taking up the general and fundamental laws of magnetism and alternating currents. This section treats of magnetic flux, permeability, saturation, E. M. F., resistance, self-induction, capacity, hysteresis, etc. Section 2 takes up various interesting discussions, such as effect of change of power factor on the voltage drop, relative weights of copper, etc., graphically illustrated. The principles of design and operation of alternating-current machinery are also treated. Another chapter is devoted to the transformer, while both the induction and repulsion motor are represented. Not the least valuable feature of the book is the treatment of the testing of alternating-current apparatus; and in general the book can be said to fill admirably the purpose for which it was intended by the author. Mention The Technical World. Builders' Architectural Drawing Self-Taught T By FRED T. HODGSON HIS work is especially designed for those who desire to learn drawing at home, a description of drawing instruments and accessories, with rules for using them, and hints as to their care and management. Rules for laying out simple drawings and executing same. The student is taught step by step to draw to scale, first the plans, next the elevations, and finally the details of a cottage, including foundations, walls, doors, windows, stairs, and all other items required for finishing a small building complete in every particular. A chapter and a number of plates are devoted to more elaborate work, and the student is shown by a series of easy lessons in simple language how to make more elaborate drawings. Theory is not considered in the work, nor is perspective or shading, as the author has endeavored to make the work a purely practical one for practical workmen. Nearly all the examples given are drawn to scale and may be followed as they are given or may be enlarged or reduced at the will of the student. As an Architectural Drawing Book for real practical workingmen, who intend making draftsmen of themselves by their own efforts, this book has no equal. LITERATURE-(Continued) this book. The chapter on Lettering seems to be among the best, as it gives directions for making the parts of letters, and shows proportions without being "fussy." The chapter on Drawing Tools and Materials imparts the desired information, but in such a textbook its logical place is at or near the beginning. In addition to the usual explanations on orthographic and isometric projections, we find a chapter on Patent-Office Drawings and an excellent treatment of "The Reproduction of Drawings." In this chapter, blue printing, photographs, the hectograph, and the mimeograph are explained. Following the subject of "Gearing,” the author describes methods and gives suggestions on flat wash, shading, and stippling. A large number of practical plates, taking up details of machines, give the student a good idea of the practical working drawing. In these exercises, the working drawings are accompanied with an isometric or oblique projection. Self-Propelled Vehicles. A practical treatise with illustrations. By J. E. Homans, A. M. 8vo. Pages 672. Black vellum, gilt top, gold titles. New York, N. Y. Theo. Audel & Co., Educational Booksellers. Price, $2.00. IN PRESENTING the new edition of this work, the publishers announce that the book has been thoroughly revised, and in large part rewritten. There is a vast amount of useful information packed into its pages, well arranged and clearly stated. The general principles of automobile construction and operation, including steering devices, underframes, wheels, tires, bearings, lubricators, are included. in the opening chapters. Then follows an exhaustive account of the theory, construction, and operation of gas engines, occupying over 100 pages. Several typical engines are taken up and discussed separately; and their properties, as regards balance, speed, and power, are discussed in the light of fundamental principles. The explanations of the governing devices are clear and valuable; while the discussion of ignition, including the hot-tube, and the primary and secondary Mention The Technical World. |