236 



SCIENCE. 



[N. S. Vol. III. No. 59. 



the bones of a hand laid upon the plate 

 holder, and subsequent plates have revealed 

 the bones of the hand and arm with start- 

 ling distinctness. (See Plate 3, Fig. 2.) 



It was possible yesterday to test the 

 method upon a broken arm. After an ex- 

 posure of 20 minutes the plate on develop- 

 ment showed the fracture in the ulna very 

 distinctly. Comment upon the numerous 

 applications of the new method in the sci- 

 ences and arts would be superfluous. 



Edwin B. Fbost. 



Hanovee, N. H., February 4, 1896. 



EXPEBI3IENTS ON THE BONTGEN X-BAYS. 



DuEiNG the past week experiments have 

 been in progress in the physical laboratory 

 of the University of Pennsylvania on the 

 Eontgen phenomena. The apparatus has 

 been gradually simplified till now only a 

 single induction coil about 12 inches long 

 and 4J inches in diameter is used. The re- 

 sistance of the primary is about 0.3 of an 

 ohm, and that of the secondary about 3,200 

 ohms. The current for the primary is sup- 

 plied by eight or ten storage cells connected 

 two in multiple arc. The Crookes tube is 

 a pear-shaped one about 1 inches long and 

 4^ inches in diameter at the larger end. 

 The exposure has been inconveniently 

 long, an hour or more giving the best re- 

 sults. 



Impressions of several surgical cases, in- 

 cluding deformed fingers, fractures, etc., 

 have been successfully produced. The re- 

 sults seem to be best where the tube is 

 about 5 inches from the sensitive plate, with 

 its longer axis vertical and the cathode at 

 the top. A card with a broad line of white 

 lead paint upon it was used, showing the 

 card transparent and the paint opaque. 



Special experiments made by Dr. H. C. 

 Hichards indicate that amethyst, quartz, 

 calc spar, mica and tourmaline are quite 

 opaque. In one of the experiments a ^- 

 inch aperture in a copper screen was placed 



2^- inches below the tube. The sensitive 

 was 3^ inches below the aperture. The 

 result showed that the raj^s in passing 

 through the opening were considerably dif- 

 fused. Experiments have been arranged to 

 examine the possible deviation of the rays 

 in passing through a wooden prism. The re- 

 sults as yet are not conclusive. The pictures 

 accompanjdng this article (see Plate 4) are 

 some of a number taken on February 5th 

 and 6th. One shows a thick leather pocket 

 purse containing a couple of coins. Upon the 

 same plate were placed a slip of thin glass 

 and a bit of aluminium tube. As is seen, 

 the glass and aluminium seem equally 

 opaque. Another of the cuts shows the 

 outlines of a pocket pincase taken by Dr. 

 E. E. Tatnall. Everj^ pin shows clearly in 

 its place. Some flowers painted upon one 

 of the surfaces are quite visible in the nega- 

 tive. 



In our experiments the sensitive plates 

 have been enclosed light-tight in an ordi- 

 nary plate holder and placed horizontally 

 upon the table beneath the tube. Upon 

 the slide of the plate holder were placed 

 the articles to be tested. 



The wide field for the development and 

 the application of the new science will be- 

 come apparent to everyone. As has al- 

 ready been suggested, it may prove to be an 

 efficient mode of examination for the sur- 

 geon. It may also be used to judge the 

 genuine from the false as in the detection 

 of a spurious diamond or other gem from 

 the real. 



As the X-rays are not light rays, but 

 probably are some form of radiant energy, 

 the writer has suggested the.term radiography 

 instead of pliotography for the new process. 



The comments of sevei'al scientists that 

 the form of wave motion transmitting the 

 energy concerned in the Rontgen pheno- 

 mena is longitudinal and not transverse, 

 have especial interest. It is shown in a 

 recent article by G. Jaumann, in Wiede- 



