VI

PREFACE.

and discussions, and makes note of all liis inventions thus farknown, particularly those bearing on polyphase motors and theeffects obtained with currents of high potential and high fre-quency. It will be seen that Mr. Tesla has ever pressed forward,barely pausing for an instant to work out in detail the utilizationsthat have at once been obvious to him of the new principles hehas elucidated. Wherever possible his own language has beenemployed.

It may be added that this volume is issued with Mr. Tesla’ssanction and approval, and that permission has been obtained forthe re-publication in it of such papers as have been read beforevarious technical societies of this country and Europe. Mr.Tesla has kindly favored the author by looking over the proofsheets of the sections embodying his latest researches. Thework lias also enjoyed the careful revision of the author’sfriend and editorial associate, Mr. Joseph Wetzler, throughwhose hands all the proofs have passed.

December, 1893 .

T. C. M.