268 LIGHT SCIENCE FOR LEISURE HOURS. 



The lightning of the mind, 

 Which out of things familiar, undesigned, 

 When least we deem of such, calls up to view 

 The spectres whom no exorcism can bind. 



The phenomena of spiritual photography were first 

 observed some years since, and a set of carte photo- 

 graphs were sent from America to Dr. Walker, of 

 Edinburgh, in which photographic phantoms were very 

 obviously, however indistinctly, discernible. More re- 

 cently an English photographer noticed a yet stranger 

 circumstance, though he was too sensible to seek for a 

 supernatural interpretation of it. When he took a 

 photograph with a particular lens, there could be seen 

 not only the usual portrait of the sitter, but at some 

 little distance a faint ' double,' exactly resembling the 

 principal image. Superstitious minds might find this 

 result even more distressing than the phantom photo- 

 graphic friend. To be visited by the departed through 

 the medium of a lens, is at least not more unpleasing 

 than to hold converse with spirits through an ordinary 

 * rappmg' medium. But the appearance of a * double,' 

 or * fetch,' has ever been held by the learned in ghostly 

 lore to signify approaching death. 



Fortunately both one and the other appearance can 

 be very easily accounted for without calling in the aid 

 of the supernatural. At a recent meeting of the Photo- 

 graphical Society it was shown that an image may 

 often be so deeply impressed on the glass that the sub- 

 sequent cleaning of the plate, even with strong acids? 

 will not completely remove the picture. When the 



