PREFACE. ix 



it involves none, and awakens pleasurable curiosity, the 

 public will follow the expositor of it with eagerness and 

 delight. 



The present work has been undertaken with this view, 

 and if it effect only part of the results expected from it, 

 it will have accomplished the object of the Author. A 

 history of science does not yet exist. Partial attempts have 

 been made, some deserving popularity although lacking 

 accuracy or completeness. Of these, Arabella Buckley's is 

 admirably done so far as it goes. Its attractive clearness 

 is beyond praise. But if its accuracy is generally unim- 

 peachable, the gaps which it presents are a grave historical 

 imperfection. Again, this or that science has been adequately 

 treated in a separate historical form ; other works, such as 

 Watts' Dictionary of Chemistry, which constitutes an in- 

 exhaustible mine of profound science, are real monuments 

 of learning ; but colossal as they are, they can be useful 

 to the historian as a source of unexcelled information as 

 regards one branch of research only. H. Spencer, too, 

 has enough material in his works to compose a magnificent 

 history of science; but such a history, we repeat, has yet 

 to be written. The book we now offer the reader is a mere 

 sketch, a simple outline of a vast subject, roughly chalked 

 as it were on the black-board, a thread in the labyrinth, 

 very slender indeed, but sufficiently strong to conduct the 

 inquirer safely from the Greek world to our own without 

 leading him astray. Facts of first-class importance only 

 have been taken into account and connected together so 

 as to show the continuity of scientific development and its 

 natural evolution. This evolution has gone through five 



