122 TRANSACTIONS OF THE CANADIAN INSTITUTE. (VoL. VIII. 
substitute contrivances are, none of them can compare with the original 
lamp of Finsen. Many of them give out rays very rich in the ultra- 
violet light, some much richer than the original lamp, and capable of 
killing germs comparatively near the surface in very much less time; 
but these more rapid germ-killers labour under the universal disadvantage 
that their rays do not penetrate so deeply as those of the original Finsen 
lamp, which gives out rays of much lower rate of vibration than they do, 
although deficient in the upper ultra-violet rays as compared with them. 
The result of all this most meritorious striving for better things has 
been not only the exercise of much ingenuity, but also the attraction of 
much earnest thought in the direction of light and light-treatment, that 
else had trended otherwhere. In many styles of substitute lamp, the 
great aim has been to bring the source of light energy closer to the part 
to be treated, also to have fewer lenses intervening, hoping thereby to 
husband many of the active rays that would otherwise be absorbed in 
the lenses and the intervening space. Again, others have incorporated 
different metals with the carbons which go to form the arc; and others 
have substituted iron or other metals for one or both carbon electrodes, 
thereby effecting a marked saving in the amount of electricity consumed, 
Fic. 5—The “ Ultra,” with iron electrodes, one of the many outcomes of the Finsen Light. 
and increasing notably the proportion of ultra-violet rays given out, the 
vapour of the burning iron giving a spectrum very rich in the wished-ior 
bactericidal ultra-violet. But these while gaining in ultra-violet, have 
lost proportionately in the less refrangible, more penetrating rays of lower 
frequency, and this fact miltates against, or even prohibits their success- 
ful use in deep seated affections. Were lupus confined to the surface of 
the skin alone, the victory would lie with the ‘‘improved” apparatus. 
But, in spite of all that has been done, the original Finsen lamp, 
with such modifications as have been introduced by the originator of 
this treatment himself, remains to-day the only reliable means of carrying 
out his light treatment in the more severe and deeper seated cases. 
And yet, wonderful is the law of compensation; all this ingenuity 
