64 FRAGMENTS OF SCIENCE. 



these invisible rays are brought to a focus, at a distance of 

 several feet from the electric lamp, the dark rays form an 

 invisible image of their source. By proper means, this 

 image may be transformed into a visible one of dazzling 

 brightness. It might, moreover, be shown, if time per- 

 mitted, how, out of those perfectly dark rays, could be ex- 

 tracted, by a process of transmutation, all the colors of the 

 solar spectrum. It might also be proved that those rays, 

 powerful as they are, and sufficient to fuse many metals, 

 can be permitted to enter the eye, and to break upon the 

 retina, without producing the least luminous impression. 



The dark rays being thus collected, you see nothing at 

 their place of convergence. With a proper thermometer it 

 could be proved that even the air at the focus is just as 

 cold as the surrounding air. And mark the conclusion to 

 which this leads. It proves the ether at the focus to be 

 practically detached from the air that the most violent 

 ethereal motion may there exist, without the least aerial 

 motion. But, though you see it not, there is sufficient 

 heat at that focus to set London on fire. The heat there 

 is competent to raise iron to a temperature at which it 

 throws off brilliant scintillations. It can heat platinum to 

 whiteness, and almost fuse that refractory metal. It 

 actually can fuse gold, silver, copper, and aluminium. The 

 moment, moreover, that wood is placed at the focus it 

 bursts into a blaze. 



It has been already affirmed that, whether as regards 

 radiation or absorption, the elementary atoms possess but 

 little power. This might be illustrated by a long array of 

 facts; and one of the most singular of these is furnished 

 by the deportment of that extremely combustible substance, 

 phosphorus, when placed at the dark focus. It is 

 impossible to ignite there a fragment of amorphous phos- 

 phorus. But ordinary phosphorus is a far quicker 

 combustible, and its deportment toward radiant heat is still 

 more impressive. It may be exposed to the intense radia- 

 tion of an ordinary fire without bursting into flarne. It 

 may also be exposed for twenty or thirty seconds at an 

 obscure focus, of sufficient power to raise platinum to a 

 red heat, without ignition. Notwithstanding the energy 

 of the ethereal waves here concentrated, notwithstanding 

 the extremely inflammable character of the elementary body 

 exposed to their action, the atoms of that body refuse to 



