PREFACE 



TO THE THIRD EDITION, 



TN the Prefaces to the previous Editions of this work, sev- 

 eral remarks were made which it is not necessary now to 

 repeat to the same extent. That a History of the Sciences, 

 executed as this is, has some value in the eyes of the Public, 

 is sufficiently proved by the circulation which it has ob- 

 tained. I am still able to say that I have seen no objection 

 urged against the plan of the work, and scarcely any against 

 the details. The attempt to throw the history of each sci- 

 ence into EPOCHS at which some great and. cardinal discovery 

 was made, and to arrange the subordinate events of each 

 history as belonging to the PKELTJDES and the SEQUELS of 

 such Epochs, appears to be assented to, as conveniently and 

 fairly exhibiting the progress of scientific truth. Such a 

 view being assumed, as it was a constant light and guide to 

 the writer in his task, so will it also, I think, make the view 

 of the reader far more clear and comprehensive than it could 

 otherwise be. With regard to the manner in which this 

 plan has been carried into eifect with reference to particular 

 writers and their researches, as I have said, I have seen 

 scarcely any objection made. I was aware, as I stated at 

 the outset, of the difficulty and delicacy of the office which I 

 had undertaken ; but I had various considerations to en- 

 courage me to go through it ; and I had a trust, which ] 



