PREFACE. 



THE history of science is a sealed book, generally speaking. 

 To the multitude of readers, including in it scientific 

 students, an historical thread conducting them through the 

 bewildering field of science cannot fail to prove a welcome 

 gain. Men, as a rule, accept the fact of to-day as it 

 stands without troubling themselves about the gradual steps 

 taken in the past to reach it. They have neither the leisure 

 nor the inclination to probe the obscurity of past ages 

 themselves. They leave this task to the historian. Nor 

 have they the inclination and leisure, pressed onward as 

 they are by their daily work, to follow the historian if 

 his account is at all bulky. Time fails them. Some, no 

 doubt, have tried to become acquainted with the subject, 

 but despite its extraordinary fascination, most have given 

 up the attempt from lack of perseverance -, for very limited 

 indeed is the number of those who, commanding the time 

 and feeling the curiosity, have the application to undertake 

 the reading, say, of the twenty-four volumes of Herbert 

 Spencer, or only the half-dozen inadequate volumes of 



