GOETHE'S FARBENLEHRE. 313 



" Comparing the length of this colored spectrum with its breadth, I 

 found it about five times greater ; a disproportion so extravagant that 

 it excited me to a more than ordinary curiosity of examining from 

 whence it might proceed." This curiosity Newton gratified by insti- 

 tuting a series of experimental questions, the answers to which left no 

 doubt upon his mind that the elongation of his spectrum was due to 

 the fact " that light is not similar or homogeneal, but consists of difform 

 rays, some of which are more refrangible than others / so that, with- 

 out any difference in their incidence on the same medium, some shall 

 be more refracted than others ; and therefore that, according to their 

 particular degrees of refrangibility, they were transmitted through 

 the prism to divers parts of the opposite wall. When," continues 

 Newton, " I understood this, I left off my aforesaid glass-works ; for 

 I saw that the perfection of telescopes was hitherto limited, not so 

 much for want of glasses truly figured according to the prescriptions 

 of optick authors, as because that light itself is an heterogeneous mix- 

 ture of differently refrangible rays ; so that were a glass so exactly 

 figured as to collect any one sort of rays into one point, it could not 

 collect those also into the same point, which, having the same inci- 

 dence upon the same medium, are apt to suffer a different refraction." 



Goethe harped on this string without cessation. " The Newtonian 

 doctrine," he says, " was really dead the moment achromatism was 

 discovered. Gifted men, our own Kliigel, for example, felt this, but 

 expressed themselves in an undecided way. On the other hand, the 

 school which had been long accustomed to support, patch up, and glue 

 their intellects to the views of Newton, had surgeons at hand to em- 

 balm the corpse, so that even after death, in the manner of the Egyp- 

 tians, it should preside, at the banquets of the natural philosophers." 



In dealing with the chromatic aberration of lenses, Goethe proves 

 himself to be less heedful than usual as an experimenter. "With the 

 clearest perception of principles, Newton had taken two pieces of card- 

 board, the one colored a deep red, the other a deep blue. Around 

 those cards he had wound fine black silk, so that the silk formed a 

 series of separate fine dark lines upon the two colored surfaces. He 

 might have drawn black lines over the red and blue, but the silk lines 

 were finer than any that he could draw. Illuminating both surfaces, 

 he placed a lens so as to cast an image of the surfaces upon a white 

 screen. The result was that, when the dark lines were sharply defined 

 upon the red, they were undefined upon the blue; and that, when, by 

 moving the screen, they were rendered distinct upon the blue, they 

 were indistinct upon the red. A distance of an inch and a half sepa- 

 rated the focus of red rays from the focus of blue rays, the latter being 

 nearer to the lens than the former. Goethe appears to have attempted 

 a repetition of this experiment ; at all events he flatly contradicts 

 Newton, ascribing his result not to the testimony of his bodily eyes, 

 but to that of the prejudiced eyes of his mind. Goethe always saw 



