Vm. PREFACE. 



of applied electrical science and those deeper researches 

 into the mysteries of Nature which almost incessantly 

 throughout a life replete with superabundant labours 

 exercised his transcendent powers. 



Since the first issue of this work also there has passed from 

 us a great name and personality revered the world over and 

 but for whom submarine telegraphy would probably have 

 been set back a generation. At a time when eight years of 

 failures had culminated in the parting of the '65 Atlantic 

 and alienated the sympathetic co-operation of the Govern- 

 ment and public, Sir John Pender, with characteristic 

 courage and confidence, saved the situation by a guarantee 

 of means for a fresh effort, subsequently, as everyone knows, 

 crowned by the successful completion of the '66 cable, and 

 recovery of the '65 by Sir James Anderson. From that 

 moment the practicability of ocean telegraphy was assured, 

 and, under the guidance of Sir John Pender's unique 

 powers of administration, a vast industry arose, the benefits 

 of which to mankind can never be fully known. 

 , Great and remarkable technical progress has been made, 

 and the cable electrician and engineer to-day has vastly 

 more facilities to hand than ever before, giving him the 

 advantage of working from a higher platform than his pre- 

 decessors, and stimulating him to carry still further such 

 developments and improvements as shall be to the general 

 advantage and progress of the industry. 



I have devoted a great amount of time and pains in ihi 

 endeavour to make the testing section useful. The deri- , 

 vation of all new formulae are given in full, as it is always 

 desirable in performing a test to understand the reasons 

 underlying and supporting it ; but in order to facilitate 

 easy reference the formulae themselves are in larger type 

 so that they can be instantly distinguished. 



Since the first publication of this work 12 years ago, several 

 specialised works on different branches of the subject have 



