390 Miscellanies. 



dom, which cannot be produced by the mere vibrations of an etherial 

 medium." He thinks, that certain rays are absorbed by material 

 bodies, and that by entering into combination with their particles, 

 chemical and physical results are produced, establishing specific colors, 

 although the manner in which the combination takes effect is unknown. 

 This theory is ably sustained, but the limits of this notice, do not 

 permit any details of the reasoning. 



A satisfactory explanation of the cause of erect vision, is among 

 the most interesting solutions of the phenomena of "that master piece 

 of divine mechanism, the human eye." "It has long been a problem 

 with the learned," how objects could appear erect to the observer, 

 when the images of those objects were inverted on the retina. It has 

 been supposed by some that " infants, literally, see every thing up- 

 side down," and that, by subsequent experience, comparing the ac- 

 curate information acquired by touch, with the erroneous impressions 

 made upon the retina, they gradually learn to see objects in an erect 

 position. In explanation. Sir D. Brewster says, that the lines of vis- 

 ible direction are always perpendicular to the retina ; and all pass 

 through one single point in the cent7'e of its spherical surface ; that 

 they cross each other at this centre, so that those from the lower part 

 of the image go to the upper part of the object, and those from the up- 

 per part of the image to the lower part of the object. Hence, the ob- 

 ject is seen in an erect position " in virtue of the lines of visible direc- 

 tion being in all cases perpendicular to the impressed part of the retina." 



This small volume is replete with exhibitions of the beautiful and 

 surptising laws of light,' which extends its influence from the smallest 

 spire of grass, to the remotest orb in the heavens. It is a work in 

 which theory rests, in almost every case, on the sure basis of math- 

 ematical demonstration. 



The appendix of Professor Bache has added seriously to its value. 



5. JYote on certain experiments on the inflammation of phospho- 

 rus in a rarefied medium; communicated by Prof. A. D. Bache, 

 of the University of Pennsylvania, in a letter to the Editor dated 

 Philadelphia, March 25, 1833. — An error of the printer in the note 

 of my experiments on the inflammation of phosphorus in a rarefied 

 medium* having procured for me a rough remark from Professor 



" American Journal of Science, Vol. xviii, p. 372. 



