I4 THE HAMILTON ASSOCIATION. 
border. Some of the thinner members then stood before the 
rays, and on the screen could be distinctly traced the position 
ot the heart and ribs; even the beating of the heart and the 
movement of the diaphram were visible to the experienced eye. 
A watch in the pocket of one gentleman was also shown. 
Then a purse was used, and the coins in it were visible. 
One feature of the rays is, that they cannot be refracted, 
and so may not be used in ordinary photography. Photo- 
graphs are taken by throwing the rays direct upon the plate 
without the interception of lenses. The doctor then took a 
photograph of a deformed hand. It was exposed to the rays 
for about the space of one minute, and when developed showed 
the hand most distinctly. He developed also at the same time 
a photograph of a young man who had swallowed a ten 
cent piece. The coin could be seen located in the neck. 
Another interesting photograph showed the effect of anelectric 
current on a photographic plate. It might be described as a 
picture of lightning, and showed a remarkable likeness to plant 
growth. A practical illustration was also given of the use of 
the flouroscope, by means of which any object may be 
examined directly when the rays are turned upon it. 
As to the nature of the X rays, the doctor said that 
Roentgen himself called them the unknown rays, and 
thought they must consist of particles of the electric fluid cast 
off into the air. The French describe them as “‘ black light,”’ 
and say they are beyond the range of the solar spectrum. 
The lecturer then referred to their many uses in medical 
surgery. In the recent South African war, the doctors were 
able to locate the bullets and extract them at once. One case 
was mentioned where the bullet entered the neck and was 
discovered in the ankle. In this connection it was mentioned 
that President Garfield’s life might certainly have been saved 
had the use of the X rays been known at the time. 
Fractures and dislocations can be located at once; and 
examined. A living illustration of this process was afforded 
