and Coloured Shadows. 443 



plementary, generally different shades of blue and red, 

 and in every instance, strictly in accordance with our 

 theory, as it relates to the primary colours. 



Mr. T. Smith, in a note added to the paper in which the 

 experiment we have already noticed is described, (London 

 and Edinburgh Philosophical Magazine, vol. i. p. 255.) has 

 given some experiments with coloured tubes, which nearly 

 correspond with those of Mr. Tomlinson ; these experi- 

 ments shew the facility with which the eye may be im- 

 pressed, of which the proofs are very numerous. One of 

 the most delicate tests of this with which I am acquainted, 

 is produced by looking for an instant at a white surface 

 through a coloured glass with one eye only, then at the 

 same surface, but without the glass, with both eyes, and 

 afterwards with the eyes alternately ; when the comple- 

 mentary colours will be seen, in a slight degree, although 

 they arise from an impression made almost instantaneously. 

 Perhaps, an improvement upon this might be made, by 

 looking with both eyes, after the impression has been made 

 upon one of them, at a strip of white paper held at the dis- 

 tance of about a foot, the eyes being directed to a distant 

 object; when the overlapping parts of the complementary 

 colours would exhibit the standard, while one of these 

 colours would be seen at the same time on each side of it. 



I have confined myself in this paper to the generalization 

 of known facts: at some future time, it is my intention to 

 proceed a step farther, by shewing the connexion of these 

 facts with others which have been traced to general prin- 

 ciples; but at present, this paper is too long to admit of 

 the extension which it would require, and there will be 

 less danger of its being considered hypothetical, when my 

 theory of light has been more fully explained. It would 

 be found, however, that light whatever may he the circum- 

 stances attending it, is transmitted upon the most general 

 and invariable principles.* 



P. Cooper. 



Bowlish, November 7th, 1836. 



(To the Editor of the Records of General Science.) 



* See Abstract, paragraph 28. 



