History of the Kaleidoscope. 447 



fiirwaidness, the gentleman who was employed to manufacture 

 them under the patent, carried a kaleidoscope to show to the 

 principal Londun opticians, for the purpose of taking orders from 

 them. These gentlemen naturally made one for their own use, 

 and for the amusement of their friends ; and the character of 

 the instrument being thus made public, the tinmen and gla- 

 ziers began to manufacture the detached parts of it, in order to 

 evade the patent; while others manufactured and sold the in- 

 strnment complete, without being aware that the exclusive pro- 

 perty of it had been secured by a patent. 



In this way the invasion of the patent right became general 

 among that class of individuals against whom the law is seldom 

 enforced but in its terrors. Some workmen of a higher class 

 were encouraged to piracy by this univer?al opposition to the 

 patent; but none of the respectable London opticians would yield 

 to the clamours of their customers, to encroach upon the rights 

 of an inventor, to whom they were at least indebted for a new 

 and a lucrative article of trade. 



In order to justify these piratical proceedings, it became ne- 

 cessary to search out some combinations of plain mirrors, which 

 might be supposed to have some resemblance to Dr. Brewster's 

 instrument; and it would have been strange indeed, if some 

 theorem or experiment had not been discovered, which could 

 have been used to impose upon the great crowd, v.'hoare entirely 

 ignorant of the principles and construction of optical instruments. 

 There never was a popular invention, which the labours of en- 

 vious individuals did not attempt to trace to some remote period; 

 and in the present case, so many persons had hazarded their 

 fortunes and their characters, that it became necessary to lay 

 hold of something which could be construed into an anticipa- 

 tion of the kaleidoscope. 



The first supposed anticipation of the kaleidoscope was found 

 in Prop. xiii. and xiv. of Professor Wood's Optics, where that 

 learned author gives a mathematical investigation of the num- 

 ber and arrangement of the images formed by two reflectors, 

 either inclined or parallel to each other. This theorem assigns 

 no position either to the eye or to the ol)ject, and does not even 

 include the principle of inversion, which is absolutely necessary 

 to the production of symmetrical forms. The theorem is true, 

 whatever be the position of the object or of the eve. In order 

 to put this matter to rest, Dr. Brewster wrote a letter to Pro- 

 fessor Wood, requesting him to say if he had any idea of the 

 effects of the kaleidoscope when he wrote those propositions. 

 To this letter Dr. B, received the following- liandsonie and satis- 

 factory answer : 



" St. John's, 



