Proceedings of the British Association. 343 



Sir D. Brewster read a paper on the cause of the increase of 

 color in objects seen with the head inverted. It has been long 

 known to all artists and tourists, that the colors of external ob- 

 jects, and particularly of natural scenery, are greatly augmented 

 by viewing them with the head bent dov/n and looking back- 

 wards between the feet, that is, by the inversion of the head. 

 The colors of the western sky, and the blue and purple tints of 

 distant mountain scenery are thus beautifully developed. This 

 position of the head is a very inconvenient one ; but the effect 

 may be produced nearly to the same extent by inverting the 

 head so far as to look at the landscape backwards beneath the 

 thighs or left arm. It is not easy to describe this change 

 of color, but it may be stated that the colors of distant moun- 

 tains, which appear tame and of a French gray color when 

 viewed with the head erect, appear of a brilliant blue or purple 

 tint with the head inverted. * * While in perplexity about the 

 cause of the phenomenon in question, I had an opportunity of ob- 

 serving the great increase of light which took place in an eye in 

 a state of inflammation. This increase was such, that objects 

 seen by the sound eye appeared as if illuminated by twilight, 

 while those seen by the inflamed eye, seemed as if they were 

 illuminated by the direct rays of the sun. All colored objects 

 had the intensity of their colors proportionally augmented ; and I 

 was thus led to believe that the increase of color produced by the 

 partial or total inversion of the head, arose from the increased 

 quantity of blood thrown into the vessels or the eye-ball, — the in- 

 creased pressure thus produced upon the retina, and from the in- 

 creased sensibility thus given to the sentient membrane. Subse- 

 quent observations have confirmed this opinion, and though I can- 

 not pretend to have demonstrated it, I have no hesitation in ex- 

 pressing it as my conviction that the apparent increase of tint to 

 which I have referred, is not an optical, but a physiological phe- 

 nomenon. If this is the case, we are furnished with a principle 

 which may enable us not only to appreciate faint tints, which can- 

 not otherwise be recognized, but to perceive small objects which, 

 with our best telescopes, might be otherwise invisible. 



Mr. Snow Harris's report on the working of Whewell's ane- 

 mometer at Plymouth, was read by the secretary. The instru- 

 ment being now effectively at work, Mr. H. proposes to have 

 completed by the next meeting a graphical delineation of the in- 



