1897] MICROSCOPICAL JOURNAL 373 



The Dennis Fluorometer. 



WIJll FKONTISI IKCK. 



It is tlie function of tliis instrument to establisii, with 

 precision, the location of any foreign object within the 

 human organism which is im[)eruieable or comparatively 

 impermeable to the X-rays. In other words it is the 

 province of the tiuorouieter to enable observers to form 

 an exact and certain diagnosis in cases of presence of 

 coins, bullets, needles, calculi or any other substance 

 which is compart vely more dense in its fluoroscopic 

 shadow than the subject in which it is contained. It is 

 also its function, by eliminating the distortion of posi- 

 tion, and the distortion caused by the divergence of the 

 rays, to provide the surgeon with absolute and reliable 

 measurements in cases of dislocations, fractures or any 

 abnormal conditions of the anatomy whicli are suscepti- 

 ble of reproduction in tlie Roentgen shadow. To obtain 

 a correct shadow with a view to locating an object after 

 the parallelism of the rays is accomplished, it is abso- 

 lutely necessary to have a base for measurement. 



To accomplish its results, it })roviaes : A shadow of 

 the body or limb, is thrown on the field of the fiuoros- 

 cope or, on the sensitive plate, at the same tim*' giving 

 data which will not only enable us to make mefisuremnnts 

 but to reproduce the exact position of the body or limb. 

 It eliminates the distortion resulting from the radiation 

 of tlie force or energy known as the X ray. The distor- 

 tion caused by the [to.sition of the subject or by the radi- 

 ation of the energy, having been eliminated, it provides 

 an accurate cross-section of the body or limb, and supplies 

 anabsolutely correct right-angle, at the intersection of the 

 lines of which the foreign object will be found in the 

 body or limb. 



The fluorometer consists in a set of carefully designed 

 metallic angle pieces, which conform generally to the 

 shape of the body or limb, and which are susceptible of 



