1897] MICROSCOPICAL JOURNAL. 377 



arras of the fluorometer on the subject, the exact cross- 

 section of the patient, as shown on the fluoroscope, will 

 be made manifest. If, therefore, the cross-section is es- 

 tablished very close to the foreign object, it will be s(^en 

 at once that the first difficulty has been surmounted; tlie 

 object has been located in close juxtaposition to a thin 

 cross-section of the body or limb. 



■ Attachable to the table is a metallic grating with 

 meshes of exactly one inch. This grating, when in posi- 

 tion, is also square with reference to the table upon 

 which the patient is placed, and the normal position is 

 close to the side of the patient, opposite to the source of 

 energy. The fluoroscope is placed against this grating, 

 and it will be seen at once that measuring from any point 

 desirable, on the surface of the patient to the foreign ob- 

 ject, is but the matter of a moment. Just here two mov- 

 able pins on the arms of the fluorometer appliance come 

 into use. These pins are placed equidistant from the 

 base of the fluorometer (which is, of course, squared with 

 the table). Then when the table, with its patient, is ad- 

 justed, so that the pins or "sights" coincide with the foi-- 

 eign object, it will be known that all three are in the 

 parallelism of the rays, and that the characteristic dis- 

 tortion, caused by the angle of the rays, has been elimin- 

 ated. Measurements, taken with the eye by means of a 

 metallic grating, will tlius enable the surgeon to cliart 

 unerringly the position of the object with reference to 

 the surface of the body which contains it. 



How far "in" from the surface of the body it may I e, 

 however, is, at this point, a mystery. Now, without 

 moving the patient or disturbing the position of the 

 fluorometer, the second observation is taken. 



For convenience in using tlie fluoroscope, a section of 

 the top of the table is removable, and a proper fluoro- 

 metric appliance substituted, by means of which the sec- 

 ond right line of the right angle is determined. This 



