60 BRITISH ASSOCIATION TOR THE ADVANCEMENT OE SCIENCE. 



hood, also, that the memory is most fresh and retentive and that the nomenclature 

 of the sciences, which, from its crabbeduess and technicality, often repels us at a 

 more advanced age, is acquired almost without an effort. Although, therefore it 

 can hardly be expected that the great schools in the country will assign to the 

 Natural Sciences any important place in their systems of instruction uutil the Uni- 

 versities for which they are the seminaries set them the example, yet I cannot 

 doubt but that, the signal once given, both masters and scholars will eagerly em- 

 brace a change so congenial to the tastes of youth, and so favorable to the develop- 

 ment of their intellectual faculties. And has not, it may be asked, the signal been 

 given by the admission of the Physical Sciences into the curriculum of our academ- 

 ical education? I trust that this question may be answered in the affirmative, if we 

 are entitled to assume that the recognition of them which ha6 already taken place 

 will be constantly followed up by according to them some such substantial encour- 

 agement as that which has been afforded hitherto almost exclusively to classical lit- 

 erature. Our ability to accomplish this, with the means and appliances at our com- 

 mand, does not, I think, admit of dispute. All, therefore, that seems wanted, is, 

 on the one hand, a more equal distribution of the existing emoluments between the 

 several professions, and on the other, the admission of the claims of the sciences 

 received into our educational system to share in the emoluments which up to this 

 time, have been monopolized by the Classics. And, as it is far from my wish to 

 curtail the older studies of the University of their proper share of support — f o 

 who that has passed through a course of academical study can be insensible of the 

 advantages he has derived from that early discipline of the mind which flows from 

 their cultivation ? — I rejoice to think, that when the Legislature shall have complet- 

 ed the removal of those restrictions which have hitherto prevented us in many 

 instances from consulting the claims of merit in the distribution of our emoluments) 

 there will be ample means afforded for giving all needful encouragement to the 

 newly-recognized studies, without trenching unduly upon that amount of pecuniae 

 aid which has been hitherto accorded to the classics. In anticipation of which 

 change, I look forward with confidence to the day when the requirements at Oxford 

 in the department of Physical Sciences will become so general and so pressing, that 

 no institution which professes to prepare the youth it instructs for academical com- 

 petition will venture to risk its reputation by declining to admit these branches of 

 study into its educational courses. 



ON THE THEORY OF COMPOUND COLOURS WITH REFERENCE TO MIXTURES OF BLUE 

 AND YELLOW LIGHT. BY MR. J. C. MAXWELL. 



When we mix together blue and yellow paint, we obtain green paint. This 

 fact is well known to all who have ever handled colours; and it is universally 

 admitted that blue and yellow make green. Red, yellow, and blue being the pri- 

 mary colours among painters, green is regarded as a secondary colour, arising 

 from the mixture of blue and yellow. Newton, however, found that the green of 

 the spectrum was not the same thing as the mixture of two colours of the spec- 

 trum, for such a mixture could be separated by the prism, while the green of the 

 spectrum resisted further decomposition. But still it was believed that yellow 

 and blue would make a green, though not that of the spectrum. As far as I am 

 aware, the first experiment on the subject is that of M. Plateau, who, before 1819, 

 m ide a disc with alternate sectors of Prussian blue and gamboge, and observed 

 that, when spinning, the resultant tint was not green, but a neutral grey, inclining 



