518 Scientific Proceedings, Royal Dublin Society. 
experiment, must have been’an image of the area of radiation, and 
equal to itin size. This image I found to be irregularly circular in 
form, hazy and ill-defined round the edge, mt nal a aren of 
an inch in diameter.’ 
In connexion with this result, it is interesting to note a fact 
which must, I think, have fallen under the observation of most 
persons ite have worked at the X-Rays. There is always one 
small spot on the platinum plate which first begins to glow ; and 
it is not difficult so to regulate the current as to keep this spot 
glowing with a red heat, while the rest of the plate remains dark. 
This is evidently the area of fiercest bombardment, and it must be 
situated at or near the focus of the Cathode stream. It is irregu- 
larly circular in shape, ill-defined in its outline, and about a 
quarter of an inch in diameter. I think, therefore, we may infer 
that this glowing spot is, in fact, the area from which the X-Rays 
are emitted. 
