AT THE PHYSICO-TECHNICAL INSTITUTE 395 



is no longer possible without a combination of the former 

 literary and logical tendencies with those of modern science. 



* The majority of educated people at the present time were 

 instructed on the old lines, and have scarcely come in contact 

 with scientific ideas, or at most with a little mathematics. It 

 is men of this school who are directing our State, educating 

 our children, maintaining the standard of morality, publishing 

 the wisdom and knowledge of our forefathers. It is they who 

 must organize the changes in the mode of education of the 

 rising generation, wherever such changes are essential. The}' 

 must be encouraged in this task, or compelled to undertake 

 it, by the public opinion of all classes throughout the whole 

 nation, whether men or women, who are competent to judge/ 



Despite all the obligations resting upon him, Helmholtz 

 continued to work at his difficult problems of mathematical 

 mechanics, while in the next year he published some amplifi- 

 cations of his earlier work in optics. 



The issue of the new edition of Physiological Optics had 

 led him to some very interesting researches, the first of which 

 was published under the title 'An Attempt to enlarge the 

 Application of Fechner's Law in the Colour System', in the 

 Zeitschrift f. Psych, u. Physiol. in 1891. He starts with the 

 assumption that the totality of colours perceived by the human 

 eye is a triple complex, like that of position in space, and that 

 Newton's Law of Colour-Mixture depends upon this, by 

 transferring the less easily perceived relations of colours to 

 the composition of geometrical lines and the construction of 

 centres of gravity. Just as we may use the most dissimilar 

 measurable spatial magnitudes in order to determine any 

 position in space, so we may employ very dissimilar magnitudes 

 to define a colour. In order to obtain direct measurements 

 of the field of sensation, Fechner confined himself to the 

 alteration of light intensities with unaltered mixture of light, 

 whereas further determinations are requisite as to the size 

 of the distinguishable graduations in colour-tones, and in the 

 saturation of colours, without or even with simultaneous altera- 

 tion of brightness, as well as of the dependence of these 

 gradations upon the physically definable alterations in the 

 exciting light. Helmholtz designates his own communications 

 as hypotheses, which must be tested more precisely, but 



