R. M. Field — Roentgen Ray in Paleontology. 543 



Art. XXX V — The Use of the Roentgen Ray in Paleontology. 

 Skiagraphy of Fossils ; by Richard M. Field. With 

 Plate VIII. 



Theory of Skiagraphy. 



In the spring of 1914, while studying some fossil brachiopods 

 in the paleontological laboratory of Harvard University, the 

 idea occurred to the writer of using the Roentgen rays as a means 

 for investigating the internal or hidden structures of fossils. 

 The wonderful strides which have been made in diagnosis and 

 medical research during the past few years are well known to 

 the physician, the recent progress of whose knowledge of such 

 concealed and intricate processes as digestion, bone diseases, 

 and all sub-surface phenomena of the human body is largely 

 due to the means which the ray affords for direct observation 

 of the processes at work and the structures of the diseased and 

 fractured tissues. "With the advent of skiagraphy (X-ray 

 photography) came the possibility of retaining an accurate and 

 permanent picture of the structure to be examined. The clear- 

 ness with which the ray will skiagraph even minute details 

 upon the X-ray, or modified, photographic plate, is indeed 

 amazing. 



The writer believes that this method of investigation has 

 been little appreciated by others than those of the medical pro- 

 fession. Why should not the scientist make use of skiagraphy 

 for investigating inorganic as well as organic structures? The 

 paleontologist may ask the following questions : — 



1. Will the X-ray penetrate those inorganic substances which 

 cause petrifaction ? 



2. If penetration is effected will a skiagraph result which 

 faithfully reproduces the hidden structure of the petrifaction 

 to be examined % 



With these questions in mind the writer made a hasty sur- 

 vey of English, French and German literature to see what 

 investigations had been made along these lines. 



As early as 1895 Professor Roentgen had examined, by 

 means of the fluoroscope, a sheet of zinc composed of small 

 plates soldered laterally together with solders of different 

 metallic proportions. The different lines of shadow caused by 

 the difference in solders were visible evidence that a new 

 means had been detected for discovering flaws and chemical 

 variations in metals. The writer was at first unable to dis- 

 cover whether more had been done in developing the use of 

 the Roentgen ray for determining inorganic structures. Min- 

 eralogists are aware of the interesting discoveries of Laue and 

 Friedrich* and the recent masterly application of these results, 



* << Interferenzersclieinungen bei Roentgenstrahlen und die Raumgitter der 

 Krystalle" ; von W. Friedrich, Zeit. fur Kryst. u. Min., vol. lii, p. 58, 1913. 



