168 POPULAR LECTURES AND ADDRESSES. 



dimensions, with shape, motion, and laws of action, 

 intelligible subjects of scientific investigation. 



The prismatic analysis of light discovered by 

 Newton was estimated by himself as " the ocld- 

 " est, if not the most considerable, detection 

 " which hath hitherto been made in the operations 

 " of nature." Had he not been deflected from 

 the subject, [had he had nineteenth century 

 optical glass for his prisms] he could not 

 have failed to obtain a pure spectrum ; but this, 

 with the inevitably consequent discovery of the 

 dark lines, was reserved for the nineteenth cen- 

 tury. Our fundamental knowledge of the dark 

 lines is due to Fraunhofcr. Wollaston saw them, 

 but did not discover them. Brcwstcr laboured 

 long and well to perfect the prismatic analysis 

 of sunlight ; and his observations on the dark- 

 bands produced by the absorption of interposed 

 gases and vapours laid foundations for the 

 grand superstructure which he scarcely lived to 

 sec. Piazzi Smyth, by spectroscopic observa- 

 tion performed on the Teak of Tcncriffe, added 

 greatly to our knowledge of the dark lines 



