26-4 Geological Society. 



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

 of splitting it or cutting sections through it. 



The speaker showed ordinary photographs and skiagraphs, made 

 at slightly varying azimuths, of Xummulites laevigata and A r . vario- 

 laria, forms that strew the shores of Selsey Bill. A particularly 

 notable result was obtained in the case of -ZV. gizehensis, an 

 organism that forms the dense masses of Nummulitic Limestone 

 of which the Pyramids of Egvpt 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, such as Foraminifera. After he had begun his ex- 

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

 this direction in France, but the method as he 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-ravs 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-rays, 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 to if success is to be achieved. 



The quality 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 has stated that the results are of considerable 

 biological value. 



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 Archceoptergx, 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 

 surrounding matrix. The only portions of the skeleton visible 

 in the radiogram were those more or less raised above the general 

 surface of the slab. This result accorded with that obtained by 

 Prof. W. Branca when he similarly experimented with the Berlin 

 specimen of Arcliajoptcryx. 



