562 



SCIENCE. 



[N. S. Vol. III. No. 67. 



THE ;X-RAYS. 



To THE Editor of Science: As opportunity 

 offered experiments have been made in our 

 laboratory with the X-rays since a few days 

 after the appearance of Prof. Eoutgen's paper. 

 Of course, we have repeated most of the 

 experiments that have been announced from 

 trustworthy sources; but I recall one or two 

 observations made here that I have not seen 

 notice of, and take the liberty of offering the ac- 

 count to your journal. I use a Ruhmkorff coil 

 with Foucault interrupter. About two amperes 

 from accumulators, through the primary gives 

 about six-inch spark in the secondary. For a 

 tube I have used one of my old Crookes tubes. 

 The one I have found to work best is pear- 

 shaped, nine inches long, four inches in diameter 

 at the larger end, with a flat disc cathode in the 

 small end, set with the plane of the disc perpen- 

 dicular to the length of the tube, and for anode 

 it has a Maltese cross inserted about the middle. 

 The cross is hinged so that it may be shaken 

 down and thus not obstruct the cathode radia- 

 tion. The tube is the one designed, in Crookes 

 set, to show that the cathode radiation is in 

 straight lines and will ' cast a shadow. ' The 

 first plate I exposed was with this tube, the 

 cross of the anode being up so as to cast a 

 shadow in the end of the tube. The plate being 

 close to the tube, a clear shadow of the anode 

 was cast upon it. On repeating the experiment 

 with the sensitive plate six inches distant, 

 there was no image of the cross on the plate, 

 which was, instead, densely ' light struck ' all 

 over. This adds another to the quite numerous 

 proofs that the X-rays originate at the phos- 

 phorescent surface of the glass and not at the 

 cathode. The second observation I wish to 

 notice is a perfectly simple and commonplace 

 method of getting a sharp clear image by these 

 X-rays, which refuse to be reflected or refracted. 

 It is the use of a metal diaphragm interposed 

 between the tube and the sensitive plate. I have 

 found a metal plate with a circular hole one 

 inch in diameter, placed half an inch from the 

 tube, the tube being six inches from the sensi- 

 tive plate to give very satisfactory results.* 



*I enclose two prints, one of a hand and one of a 

 part of the forearm, showing the eiiect of a gunshot 

 wound made thirty years ago. The print shows how 



The most interesting observation is a physio- 

 logical effect of the X-rays. A month ago we 

 were asked to undertake the location of a bul- 

 let in the head of a child that had been acci- 

 dentally shot. On the 29th of February Dr. 

 Wm. L. Dudley and I decided to make a pre- 

 liminary test of photographing through the 

 head with our rather weak apparatus before 

 undertaking the surgical case. Accordingly 

 Dr. Dudley, with his characteristic devotion to 

 the cause of science, lent himself to the experi- 

 ment. A plateholder containing the sensitive 

 plate was tied to one side of his head, with a 

 coin between the plate and his head, and the 

 tube was set plaj'ing on the opposite side of his 

 head. The tube was about one-half inch dis- 

 tant from his hair, and the exposure was one 

 hour. The plate developed nothing ; but 

 yesterday, 21 days after the experiment, all the 

 hair came out over the space under the X-ray 

 discharge. The spot is now perfectly bald, 

 being two inches in diameter. This is the size 

 of the X-ray field close to this tube. We, and 

 especially Dr. Dudley, shall watch with interest 

 the ultimate effect. The skin looks perfectly 

 healthy, and there has been no pain nor other 

 indication of disorder. I called attention to the 

 place before Dr. Dudley had himself noticed it, 

 and we were both for some time at a loss to 

 account for it, as we had no previous intimation 

 of any effect whatever. 



But this little incident may bear a suggestion. 

 The X-rays are as yet unexplained ; but the 

 suggestion, beginning with Prof. Eontgen him- 

 self, has more than once been made that they 

 are longitudinal rather than transverse vibra- 

 tions. It is diflicvilt to distinguish a longitudinal 

 displacement of the ether from an electric cur- 

 rent, as far as it goes. It is a well-known 

 method of exterminating hair, that of sending 

 a current to its roots by a needle. If any such 

 quasi electric current has resulted from the 

 X-rays the effect upon the hair might be thus 

 accounted for. The intensity of the discharge 

 was not sufficient to heat the tube except very 



the ulna, some inches of which was shot away, has 

 attached to the radius, and also shows some half a 

 dozen shot still in the arm. It would have been diiB- 

 eult to get such clear shadowgraphs of objects so large 

 as these without a diaphragm. 



