CHAPTER XIX 



THE DEVELOPMENT OF MECHANICS: THE 

 FORERUNNERS OF NEWTON 



BEYOND doubt, with all his dreams in the day, the mechanical 

 conceptions and ideas of Descartes, his thought of reducing all 

 phenomena to the regular and calculable movements of a 

 mechanism, exercised a profound influence upon the thought 

 of the time. His Principia appeared in 1644 ; its preponderant 

 influence outlasted near a century ; physical science has perhaps 

 never quite lost its impress. 



The work of Descartes did much ; that of Galileo, with its 

 more solid foundations, did more. Galileo's Dialogues on 

 Mechanics came in 1638. With the faithful aid of Viviani 

 and Torricelli, he added during the last three months of his 

 life two supplementary dialogues. The work appeared from 

 Leyden ; they would not, of course, let him publish it in Italy. 

 Coming from such a man it was read all over Europe with a 

 profound interest. 



It is curious to observe how distinct was the work of the 

 two men, to note what little use Descartes made of Galileo's 

 discoveries. His intellectual egotism carried him so far as to 

 put out of his reach materials of the greatest value. It appears 

 that of any sort of writing, that which influenced him most 

 was Harvey's little tract on the circulation of the blood. It 

 had appeared in 1629. It was written wholly in the mechanical 

 spirit ; it shows clearly that Galileo and Descartes were alike 

 but a part of their time, and that the time had taken on a 

 distinctly mechanical bent. 



That bent was intensified, the seventeenth century be- 

 came pre-eminently the century of mechanics through the re- 

 markable discovery that came the year after Galileo's death. 

 This was the elucidation of the theory of the suction-pump, 

 and through it the discovery of the weight of air, the develop- 

 ment of pneumatics. Our common pump is old enough ; its 



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