SIR DA VID BRE WSTER. 1 9 1 



reward to the inventor, and was so completely anticipated, as 

 in the case of the kaleidoscope. The very announcement of the 

 patent, by which the discovery was intended to be secured, 

 was immediately followed by an infringement so extensive as to 

 leave all legal redress unattainable. But the piracy did not 

 terminate here ; for various attempts were made to deprive its 

 author, Sir David Brewster, of the merits of the discovery, and 

 to refer it to Baptista Porta, Harris, Wood, Bradley, &c. All 

 these were very satisfactorily answered by Sir David Brewster, 

 confirmed by Professor Playfair, Mr. Watt, and Professor Pictet, 

 who attested the originality of the invention. 



It was in the year 1814, when Sir David Brewster was engaged 

 in experiments on the polarization of light by successive reflec- 

 tions between plates of glass, the reflectors being in some cases 

 inclined to each other, that he had occasion to remark the 

 circular arrangement of the images of a candle round a centre, 

 or the multiplication of the sectors formed by the extremities of 

 the glass plates. In repeating at a subsequent period the 

 experiments of M. Biot on the action of fluids upon light, 

 Brewster placed the fluids in a trough formed by two plates 

 of glass cemented together at an angle. The eye being neces- 

 sarily placed at one end, some of the cement which had been 

 pressed through between the plates appeared to be arranged 

 into a regular figure. The symmetry of this figure being very 

 remarkable. Sir David Brewster set himself to investigate the 

 cause of the phenomenon, and in doing this he discovered the 

 leading principles of the kaleidoscope. 



Upon these principles Sir David Brewster constructed an 

 instrument, in which he fixed permajiently, across the ends of 

 the reflectors, pieces of coloured glass and other irregular ob- 

 jects ; but the great step towards the completion of the instru- 



