X, PEEFACE. 



I heartily thank the reviewers of the first edition for 

 indicating the points in which this work needed improve- 

 ment. I have consulted from time to time the above 

 mentioned standard works on Testing and duly acknow- 

 ledged the same in the body of the book. I am also 

 grateful to many personal friends from whom I have had 

 the advantage of suggestions at various times, and to Mr. 

 P. Burrell, of the Eastern Telegraph Company, who aided 

 me and pointed out the manner in which the testing 

 section could be made most useful to those qualifying for 

 the various grades in the service. 



In its present form, if this work shall help to maintain 

 and foster the desire for progress and development and 

 prove of assistance to those who are endeavouring to attain 

 greater efficiency in this interesting art, I shall always have 

 the satisfaction of knowing that my labours have not been 

 in vain. 



H. D. Wilkinson. 



4, Queen Street Place, London, E.G., 



August, ic 



