PREFACE TO THE SECOND EDITION.
The great favor with which the first edition of this little work has been received and the steadily growing interest in its subject, together with many valuable improvements and researches, may be given as the reasons for this new edition.
The book has been thoroughly revised, partly rewritten, and considerable new matter, with twenty-six new illustrations, added. It has been brought up to date as far as electrical science has gone.
To detail all that has been done is too great a task for a preface; we may briefly mention the following new matter:
Coils for gas and automobile engines; medical coils, concise directions for operation and repairs; new forms of contact breakers, including electrolytic and mechanical; gas-lighting apparatus; primary and secondary batteries.
The chapter on X-Ray Apparatus has been entirely rewritten, and is thoroughly practical; and an entire chapter on Wireless Telegraphy has been added. In a book of this size it is not feasible to give specific directions and full dimensions for the manufacture of all the apparatus described. Indeed, much of the latter must be adapted to the particular purpose for which it is to be utilized. Again, the same amount of material will not always produce the same results. A little closer winding, greater pressure applied to the cooling wax of a condenser, and the output or capacity of either is changed.
Matters purely of design or taste are to be governed by the creative faculty of the worker; but such general details and rules are given as will be sufficient to enable one possessing ordinary constructive ability to make his own apparatus.
The whole process of coil-making does not require high mechanical skill, but chiefly patience and attention to details; and, perhaps best of all, but few tools are needed, all of a simple kind.
We beg to acknowledge courtesies received from Messrs. Queen & Co., the Scientific American for frontispiece and Fig. 13, Mr. Goldingham's book on Oil Engines for Fig. 12, and others who have been of assistance to the author. The best American and English practice has been adopted; the American standard gauges and sizes of wires are used, except where noted.
A list of works, particularly of value to the coil worker, will be found following the index.
H. S. Norrie
(Norman H. Schneider.)
April, 1901.