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that direction, might, by the use of ordinary intelligence, and a 
little 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- 
- eandescent 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 iscolour? The great advance made 
by Wollaston in 1802, by the use of a narrow slit 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 complimentary colours. Dr. Wollaston, 
examining sunlight, as Newton had done more than a century 
before, found that the narrow slit 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. This 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, &. This discovery 
constituted a sort of foundation stone in modern spectrum analysis. 
‘The addition of a lens by Mr. Simms and Professor Swann, to the 
ae 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 
_ineandescent body, either solid or liquid, gave a continuous spec- 
