February 26, 1920] 



NATURE 



697 



of their work, a feature which a photographer 

 would never be guilty of neglecting. 



About half the exhibition was devoted to medical 

 radiography, and the extraordinary progress that 

 has been made since the discovery of the X-rays 

 twenty-five years ago was strikingly brought out by 

 the juxtaposition of two prints of the human hand 

 (Fig. i), one taken in January, 1896, by Campbell 

 .Swinton, with an exposure of twenty minutes, and 

 the other in December, igig, by Knox, with a 

 single-impulse flash occupying about i/ioo sec. In 

 the former the bones can be seen, though only 

 blurred; in the latter (with i '120,000 of the ex- 

 posure) every detail is brilliantly portrayed. Knox 

 further showed a fine series of flash radiographs of 

 the chest (Fig. 2). Detection of stones in the kidney 



Some of the most attractive prints were those of 

 shells and rare fossils taken by Rodman ; the 

 results reminded one irresistibly of the designs 

 which the harmonograph traces out. Henri Beclere 

 showed a new application of the rays in the radio- 

 graphing of finger-prints. The skin is first rubbed 

 over with red lead, and the radiograph shows the 

 surface markings and openings of the cutaneous 

 glands in so vivid a fashion as to suggest that the 

 method would have advantages over that normally 

 employed by the Criminal Investigation Depart- 

 ment. 



Several examples of negative prints on radio- 

 bromide paper were exhibited, the most remark- 

 able being that of the skeleton of a man. This 

 radiograph, which was contained en a single sheet, 



Fig. 2. — Klasli radio^^raph ofchest. (Knox.) 



and bladder is now relatively straightforward 

 work, as the constituent oxalates and phosphates 

 are dense enough to cast good shadows. Until 

 recently gall-stones (consisting chiefly of chole- 

 sterin) were deemed impossible of detection, but 

 the radiographer acquires astounding skill in the 

 interpretation of faint shadows, and both Thurstan 

 Holland and Knox showed fine examples of 

 success in diagnosing this troublesome complaint. 

 Fig. 3 is an example of Thurstan Holland's work 

 in barium-meal radiography. 



A number of war radiographs were shown ; one 

 calling for comment was by Finzi of a bullet in 

 the heart of a man who, it may be added, is still 

 alive. Of interest also was the radiograph of the 

 hand of an Egyptian mummy- — a princess of the 

 Second Dynasty (1500 B.C.) — with a scarab ring on 

 the third finger. (Evidently an X-ray equipment 

 will have to be added to the Egyptologist's outfit !) 

 NO. 2626, VOL. 104] 



\ \i\. 3,- Kight iliac fos^a after a banuin meal, showing appendix, cajcum 

 ascending colon (with "filling defect " due to' malignant growth), an 

 transverse colon. (Thurstan Holland.) 



8 ft. by 4 ft., was taken by Forder with a Coolidge 

 bulb working 8 ft. away. 



The use of the X-rays for revealing the interior 

 of plant life is comparatively recent. Considerable 

 differences exist in the mineral content and 

 density, and hence in the transparency, of the 

 different parts of a plant — root, stem, leaf, flower, 

 fruit, seed, etc. It thus happens that even the 

 most delicate structures of plants can be laid bare 

 without tearing the plant to pieces in order to 

 study it. Microscopic detail is, of course, not re- 

 vealed. Long-waved X-rays are required for such 

 work, of which Knox showed some good flower 

 illustrations. 



In the case of timber the different varieties 

 absorb X-rays to different degrees. Peculiarities 

 in the structure and course of the fibres (such as 



