PREFACE TO THE ENGLISH EDITION. 



A S in the former work, The Forces of Nature, done into 

 English by the same hands to which work, dealing 

 with Science pure, the present, dealing with Science applied, 

 is complementary the endeavour has been made to bring 

 the different subjects up to date. In carrying out this 

 object, both Translator and Editor have received help from 

 many kind friends skilled in various technics. 



Amongst those to whom their thanks must be here 

 tendered, are Mr. William Chappell, Mr. Baillie Hamilton, 

 Mr. G. I. F. Cooke, and Mr. Hermann Smith, who have 

 made additions to the chapters on musical instruments ; and 

 Mr. N. J. Holmes, who has revised the description of the 

 organ and given permission to publish an engraving and 

 description of his own magnificent instrument. Thanks 

 are also due to the same gentleman for additional infor- 

 mation respecting telegraphic- instruments ; to Captain 

 Abney, who has added some valuable information regarding 

 photographic printing processes ; to the Rev. S. J. Perry, 

 who has looked over the description of the instruments 

 used in the study of terrestrial magnetism ; to Mr. Aitchison, 

 who rendered assistance in the chapters on the Steam-engine, 

 and to Mr. Glaisher, who has been good enough to make 

 some corrections in the chapters on ballooning. 



