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that direction, might, by the use of ordinary intelhgeuce, and a 

 Httle more than ordinary patience, acquire a knowledge of the facts 

 and methods ot this science, that truer and better knowledge which 

 came from observation and experiment was not so readily accessible. 

 Using therefore, such apparatus as he had at his disposal, he would 

 endeavour to give at least some glimpses of this fascinating and 

 important science. The first illustration was the famous and 

 historical experiment of Newton. Using the oxy-hydrogen light as 

 a substitute for the sun, the beautiful continuous spectrum of in- 

 candescent lime was produced by means of a carbon disulphide 

 prism. The recomposition of white light was effected by the 

 introduction of a second carbon disulphide prism put in a reversed 

 position. The lecturer proceeded to answer two questions ; first, 

 what is light ? Second, what is colour ? The great advance made 

 by Wollaston in 1802, by the use of a narrow sht parallel to the 

 refracting edge of the prism, thereby securing a pure spectrum, 

 was noted. The optical character of a prism was briefly described, 

 and this was followed by a statement of Newton's discovery that 

 the best effect of a prism is obtained when it is so placed that the 

 ray under examination leaves the prism at exactly the same angle 

 at which the incident ray falls upon it, the angle of minimum 

 deviation. The spectrum was again thrown upon the screen, and 

 a series of interesting experiments shown, illustrating the doctrine 

 of colour. This was the more important, as colour was the special 

 domain of spectrum analysis. The experiments included absorp- 

 tion, subjective colours, and comphmentary colours. Dr. Wollaston, 

 examining sunlight, as Newton had clone more than a century 

 before, found that the narrow sht he had introduced, enabled him 

 to correct the observation of Newton, that the solar spectrum was 

 continuous. Wollaston found, on the contrary, that it was divided 

 or crossed by many narrow dark lines. Thie discovery was of the 

 most vital importance. In 1814, Fraunhofer, a German optician, 

 working quite independently, mapped out 576 of these lines in the 

 solar spectrum, hence called Fraunhofer's lines, the more con- 

 spicuous and important being lettered A, B, C, &c. This discovery 

 constituted a sort of foimdation stone in modern spectrum analysis. 

 The addition of a lens by Mr. Simms and Professor Swann, to the 

 prism and slit, by which more light and better definition were 

 obtained, was remarked upon. The construction of the modern 

 spectroscope, for physical, chemical, and astronomical research, 

 was briefly described, as was also a very large direct-vision spec- 

 troscope on the lecture table The lecturer next stated, and 

 experimentally illustrated, some of the more important generaliza- 

 tions of the science of spectrum analysis. The fact that an 

 incandescent body, either solid or liquid, gave a continuous spec- 



