PROGRESS OF HUMAN KNOWLEDGE. 11 



The perfection of the instruments now applied to 

 experimental research deserves study in itself, as an 

 attestation of human progress. Seneca somewhere de- 

 precates all manual methods and inventions as beneath 

 the dignity of philosophy. Modern science dignifies 

 and hastens to appropriate them, whatever they be. 

 A common catalogue would contain all the admirable 

 inventions of apparatus serving the purposes of each 

 science, and enabling one science to minister to 

 the progress of another. Look, for instance, at the 

 various aids which electricity has rendered to all the 

 sciences, through instruments depending on its pheno- 

 mena such as the thermoscope, the electric lamp, the 

 electric apparatus connected with telescopes for transit 

 observations, the electric telegraph, and the many 

 admirable devices by which this wonderful agent its 

 current simply cut off or restored is made to record 

 almost instantaneously, whatever the distance, the 

 words of human intercourse, and to register the most 

 subtle phenomena of the natural w T Orld. The various 

 apparatus by which the electric element itself is 

 evolved, directed, and multiplied in quantity or inten- 

 sity, illustrate equally well this instrumental perfection. 

 Strange that it should have been thus far attained, 

 while we yet are ignorant what electricity really is ! 1 



What has been said of experiment as bearing on 



1 The researches of Matteucci, Du Bois Raymond, and Helmholtz on 

 animal electricity, and on the rate of transmission of the nervous agent 

 through the nerves, muscles, and brain, have required and produced 

 instrumental apparatus of the most consummate delicacy as well as 

 complexity. The same description may be given of the instrumental 

 means employed by Wheatstone, Foucard, and Fizeau to determine the 

 velocity of electricity and light. 



