452 On the Kaleidoscope. [June, 



both these contrivances, and from every optical instrument with 

 which I am acquainted, the kaleidoscope appears to differ essen- 

 tially both in its effect and in the principle of its construction. 



" As to the effect, the thing produced by the kaleidoscope is a 

 series of figures presented with the most perfect symmetry, so 

 as always to compose a whole, in which nothing is wanting and 

 nothing redundant. It matters not what the object be to which 

 that instrument is directed ; if it only be in its proper place, the 

 effect just described is seen to take place, and with an endless 

 variety. In this respect the kaleidoscope appears to be quite 

 singular among optical instruments. Neither the instrument in 

 Bradley, nor the theorem in Wood's book, have any resemblance 

 to this. Next as to the principle of construction, Dr. Brewster's 

 instrument requires a particular position of the eye of the 

 observer of the object looked at in order to its effect. If either 

 of these is wanting, the symmetry vanishes, and the figures are 

 irregular and disunited. 



" For these reasons, Dr. Brewster's invention seems to me 

 quite unlike the other two." 



Perhaps we could scarcely have a stronger proof of the novelty 

 of the invention than the effect which it produced when it was 

 first exhibited in London ; both the scientific and the unscientific 

 were equally amused and surprised at its effects ; and although 

 the principle on which it acts was easily perceived to be one with 

 which we were familiar, yet the mode of its application was what 

 no one had before witnessed. 



The Editors have also received the following notice respecting 

 the kaleidoscope, which they subjoin, as tending to complete the 

 history of this curious instrument, and to show what approaches 

 had been made to the invention by the older writers. 



On the Kaleidoscope. 

 In Kircher's Ars Magna Lucis et Umbra?, published at Rome 

 in 1646, there is an account of the experiment, which has of 

 late created so much amusement, under the name of the kalei- 

 doscope. At p. 890 of that work is a description of the appear- 

 ance of the circle divided into its aliquot parts (which Dr. 

 Brewster's tube so beautifully exhibits), by means of two plane 

 mirrors, which are set at the angles of 120°, 90°, 72°, &c. See. 

 with one another. He afterwards goes on to describe the 

 multiplication of images by reflections from mirrors, set in 

 different situations with one another, and expressly mentions 

 the variety of combinations which may be produced by changes 

 in the objects which are reflected. Kircher claims the experi- 

 ment as his own, saying that he had not heard of its having 

 occurred to any one before him. S. 



