216 Electric Shadows and Luminescence. [May 8, 



nescent stuffs, several platino-cyanirles, several sulphides, and some 

 samples of tungstate of calcium. Of these materials the brightest 

 in luminescence is the hydrated platino-cyanide of potassium em- 

 ployed by Mr. Sydney Jackson ; the next brightest is a French sample 

 of platino-cyanide of barium; platino-cyanide of strontium coming 

 third. 



Using a focus tube of Mr. Jackson's improved pattern, enclosed 

 in a box with a cardboard front, and taking a platino-cyanide screen, 

 I am able in conclusion to demonstrate to all those of my audience 

 who are within a few feet of the apparatus, the facts that have so 

 startled the world You can see the bones of my hand and of my 

 wrist. You can see light between the two bones of my forearm ; 

 while metal objects, keys, coins, scissors, &c., enclosed in boxes, 

 embedded in wood blocks, or locked up in leather bags, are plainly 

 visible to the eye. 



Whatever these remarkable rays are, whether they are vortices in 

 the ether, or longitudinal vibrations, or radiant matter that has 

 penetrated the tube, or, lastly, whether they consist simply of ultra- 

 violet light, their discovery affords us one more illustration of the 

 fact that there is no finality in science. The universe around us 

 is not only not empty, is not only not dark, but is, on the contrary, 

 absolutely full and palpitating with light : though there be light 

 which our eyes may never see, and sounds which our ears may never 

 hear. But science has not yet pronounced its last word on the 

 hearing of that which is inaudible and the seeing of that which is 

 invisible. 



[S. P. T.] 



