VI PREFACE. 



A perusal of these volumes will show that, like other 

 inventors, Sir William Siemens was not uniformly fortunate 

 enough to attain the results he anticipated from his inven- 

 tions ; the faithful record of his attempts to overcome diffi- 

 culties, and of his uniform practice to investigate thoroughly 

 the scientific basis of the various problems, will, it is hoped, 

 be of use to those who are following similar lines of research. 



These volumes may be regarded as complementary to 

 " The Life of Sir William Siemens," by Dr. William Pole, 

 F.R.S. ; and the Executors take this opportunity of publicly 

 expressing their thanks for the admirable manner in which 

 Dr. Pole has accomplished his arduous task, and for the 

 kindness with which Messrs. Macmillan have permitted the 

 use, as frontispiece, of the portrait of Sir William Siemens 

 published in Nature shortly after Sir William Siemcns's 

 death. 



The Executors desire to express their appreciation of the 

 careful manner in which these volumes have been edited by 

 Mr. Bamber ; and for the valuable assistance rendered in 

 their compilation, the special thanks of the Executors are 

 due to Mr. J. Head, who for many years held the responsible 

 and important position of manager of Sir William's metal- 

 lurgical business, and who, since Sir William Siemens's 

 death, has continued to act in the same capacity for Mr. 

 Frederick Siemens. 



It has, moreover, been possible to present the papers in 

 their present complete form only through the kindness and 



