490 ON THE INTERDEPENDENCE OF SCIENCE 



extent by the bones, so that the plate is little acted upon in the parts opposite 

 to them, while the portions corresponding to the muscles and other soft parts 

 are influenced in an intermediate degree. Thus a picture is obtained in which 

 the bones stand out in sharp relief among the flesh, and anything abnormal 

 in their shape or position is clearly displayed. 



I need hardly point out what important aid this must give to the surgeon. 

 As an instance, I may mention a case which occurred in the practice of Mr. 

 Howard Marsh. He was called to see a severe injury of the elbow, in which 

 the swelling was so great as to make it impossible for him by ordinary means of 

 examination to decide whether he had to deal with a fracture or a dislocation. 

 If it were the latter, a cure would be effected by the exercise of violence which 

 would be not only useless but most injurious if a bone was broken. By the aid 

 of the Rontgen rays a photograph was taken in which the bone of the upper arm 

 was clearly seen displaced forwards on those of the forearm. The diagnosis 

 being thus established, Mr. Marsh proceeded to reduce the dislocation ; and 

 his success was proved by another photograph which showed the bones in their 

 natural relative position. 



The common metals, such as lead, iron, and copper, being still denser than 

 the osseous structures, these rays can show a bullet embedded in a bone or a 

 needle lodged about a joint. At the last conversazione of the Royal Society, 

 a picture produced by the new photography displayed with perfect distinctness 

 through the bony framework of the chest a halfpenny low down in a boy's 

 gullet. It had been there for six months, causing uneasiness at the pit of the 

 stomach during swallowing ; but whether the coin really remained impacted, 

 and if so, what was its position, was entirely uncertain till the Rontgen rays 

 revealed it. Dr. Macintyre, of Glasgow, who was the photographer, informs 

 me that when the presence of the halfpenny had been thus demonstrated, the 

 surgeon in charge of the case made an attempt to extract it, and although this 

 was not successful in its immediate object, it had the effect of dislodging the 

 coin ; for a subsequent photograph by Dr. Macintyre not only showed that it 

 had disappeared from the gullet, but also, thanks to the wonderful penetrating 

 power which the rays had acquired in his hands, proved that it had not lodged 

 further down in the alimentary passage. The boy has since completely 

 recovered. 



The Rontgen rays cause certain chemical compounds to fluoresce, and 

 emit a faint light plainly visible in the dark ; and if they are made to fall upon 

 a translucent screen impregnated with such a salt, it becomes beautifully illu- 

 minated. If a part of the human body is interposed between the screen and 

 the source of the rays, the bones and other structures are thrown in shadow 



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