_Photographs by artificial Lights_.--May I ask for references to any
manuals of photography, or papers in scientific journals, in which are
recorded any experiments that have been made with the view of obtaining
photographs by means of artificial lights? This is, I have no doubt, a
subject of interest to many who, like myself, are busily occupied during
the day, and have only their evenings for scientific pursuits: while it is
obvious, that if such a process can be successfully practised, there are
many objects--such as _prints_, _coins_, _seals_, _objects of natural
history and antiquity_--which might well be copied by it, even though
artificial light should prove far slower in its action than solar light.