DISSERTATION SECOND. 



PART I. 



In conformity to the plan which has been traced and exe- 

 cuted with so much ability in the First Dissertation, I am 

 now to present the reader with an historical sketch of the 

 principal discoveries made in Natural Philosophy, from the 

 revival of letters down to the present time. In entering 

 on this task, and on looking at the instructive but formida- 

 ble model already set before me, I should experience no 

 small solicitude, did I not trust that the subject of which I 

 am to speak, in order to be interesting, needs only to be 

 treated with clearness and precision. These two requi- 

 sites I will endeavour to keep steadily in view. 



In the order which I am to follow, I shall be guided 

 solely by a regard to the subserviency of one science to 

 the progress of another, and to the consequent priority of 

 the former in the order of regular study. For this reason, 

 the history of the pure Mathematicks will be first consider- 

 ed, as that science has been one of the two principal instru- 

 ments applied by the moderns to the advancement of natu- 

 ral knowledge. The other instrument is Experience ; and, 

 therefore, the principles of the inductive method, or of the 

 branch of Logick which teaches the application of ex- 

 periment and observation to the interpretation of nature, 



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