VI PROCEEDINGS OY THE GEOLOGICAL SOCIETY. [vol. lxxiv,. 



facilitated by the application of X-rays, which removes the necessitv 

 of splitting the test or cutting sections through it. 



The speaker showed ordinary photographs and skiagraphs, made 

 at slightly varying azimuths, of Nummulites laevigata and 

 JV. variolaria, forms that strew the shores of Selsey Bill. A 

 particularly notable result was obtained in the case of A 7 ", gizek- 

 ensis, an organism that forms the dense masses of Nummulitic 

 Limestone of which the Pyramids of Egypt and the Citadel at 

 Cairo are built. 



Mr. Barnard said that, although the utilization of X-rays to 

 determine the internal structure of various bodies was well known, 

 he was not aware that the method had been successfully applied to- 

 small objects, sucli as foraminifera. After he had begun his ex- 

 periments he found that M. Pierre Groby had done some work in 

 this direction in Prance, but the method as Goby described it is 

 surrounded with considerable mystery and elaboration of apparatus, 

 which appear quite unnecessary. The speaker's results were 

 arrived at independently ; in fact, they are really a side issue. 



His original experiments were directed rather towards the use of 

 X-rays in obtaining magnified images, altogether apart from the 

 usual skiagraphic methods in which, a shadowgraph is, in fact, all 

 that can be produced. The primary object has not yet been 

 achieved, although there is some reason to hope that it may 

 ultimately come to pass. The results shown by Mr. Heron-Allen 

 are obtained by quite simple means. A very narrow beam of 

 X-raj^s, such as would be termed ' a parallel beam ' when speaking 

 in terms of ordinary light, is allowed to impinge on the object, 

 the latter being in contact with the photographic plate. The 

 negative produced is, therefore, of the same size as the object. 

 Photographic enlargement is then resorted to, and the result had 

 been shown on the screen. 



There are two points that require careful attention if success is 

 to be achieved. The qualit} r of the X-rays must be suited to the 

 object. In nearly all cases of small objects, what are known as 

 'soft' X-rays must be used, and the degree of softness is the crux of 

 the whole matter. The photographic plate must be of exceedingly 

 fine grain, otherwise the amount of enlargement that can be obtained 

 is very limited. Difficulties in this direction have been overcome, 

 and Mr. Heron-Allen states that the results are of considerable 

 biological value. 



A short discussion followed, and the thanks of the Fellows 

 present were accorded to Mr. Heron-Allen and Mr. Barnard for 

 their demonstration. 



Dr. A. Smith Woodward, F.R.S., V.P.G.S., exhibited a radio- 

 gram of the original slab of lithographic stone containing the 

 skeleton of Archceopteri/x, made for the British Museum by 

 Dr. Robert Knox in 1916. It was evident that the penetrability 

 of the fossil bones to the X-rays was the same as that of the 



