1897 1 MICROSCOPICAL JOURNAL. 375 



graphs, and, as a consequence, two views taken at right 

 angles, would not disclose the location of the object. It 

 was at once apparent that the visible effect of the Roent- 

 gen ray, whether in its action on a sensitive plate or pa- 

 per, or its visual effect on the fluorescent screen, is a 

 shadow only. It must be remembered that we are deal- 

 ing with a shadow, which is not only treacherous, but is 

 lacking in the dimension of thickness. When the X ray 

 once starts it goes straight to infinity. Thus it has hap- 

 pened in many cases that, while apparently a bullet or 

 needle, for instance, was located in a certain position 

 with reference to the anatomy, as shown by a skiagraph, 

 it would be found that it was not at the place indicated. 

 It is not necessary to enlarge upon this branch of the 

 distortion, for it is familiar not only to every experimen- 

 ter on the lines of the Roentgen rays, but to every sur- 

 geon who has made a skiagraph the basis of exploration. 

 The only practical solution of the difficulty is to estab- 

 lish a definite cross section of the patient by means of 

 angle pieces, which would be less permeable than any 

 portion of the subject, and which could be made to re- 

 tain their relative position to the subject, and with the 

 parallelism of the rays through the process of producing 

 the angles. Having established this cross-section, it 

 was found that it was desirable that it should be formed 

 in close proximity to the foreign object, which had been 

 superficially located by means of the fluoroscope. An ap- 

 pliance was perfected which conforms in a general way 

 to the shape of the body, the neck, the head, the foot or 

 the limb, and which at the same time preserves the posi- 

 tion of the body squarely in its relation with an adjust- 

 able table. This adjustable table is extremely simple, 

 and is so arranged that when the patient is placed in the 

 position desired, the fluorometer will rest in a groove on 

 the table, in one case, and an attachment of the table in 

 the other. Then the desired position having thus been 



