164 



DISCOVERY 



and at the same time of striking interest, is not b}' any 

 means a simple matter. For instance, a very large in- 

 strument for estimating the heating powers of gas — 

 " The ' Boys ' Integrating and Recording Gas Calori- 

 meter " — while fascinating in its intricacy, was perhaps 

 of too complicated design to be understood save by the 

 expert, after careful study. 



Great interest was taken in a " stream-line filter " 

 exhibited by Dr. Hele-Shaw, F.R.S. Everyone is familiar 

 with the waste of time involved in filtering fluids contain- 

 ing suspended matter by ordinary means. Yet filtration is 

 a process which is essential every moment in laboratories. 

 In this new filter, a most simple device is employed with 

 extraordinary success. Holes about half an inch in 

 diameter are punched through a series of sheets of paper — 

 the eventual effect being rather as if one had pushed a 

 cheese scoop through a magazine several times. The 

 dirty water is then forced tlirough these holes by a pump, 

 while the sheets of paper are forced together with a vari- 

 able strength. The water is only allowed to escape 

 between the leaves of paper, and since that space is ex- 

 ceedingly small, all solid matter remains behind in the 

 large punched-out spaces. Even a dye, such as methylene 

 blue, if put through the filter, comes out colourless, and 

 it must be remarked that this is in no sense the effect 

 of what is called " adsorption " — a physico-chemical 

 process by which a kind of combination between dye 

 and paper takes place — but a true filtration, or mechanical 

 removal of suspended matter. 



]NIr. John Walton, of the Botany School, Cambridge, also 

 selected a simple and yet most interesting demonstration. 

 Fossil plants, while common enough, are rather disappoint- 

 ing to the botanist, since they show little detail. In 

 Mr. Walton's new method of e.xamination, an impression 

 of the fossil is taken on a gum known as balsam. The 

 rock is then dissolved oS with acid. The results are 

 amazing. Every tiny detail of hairs, cells, and water- 

 conduction systems of the leaves is revealed with absolute 

 clearness, and, instead of a faint impression on a rock, 

 we are face to face with what appears to be a living plant, 

 which grew and faded away many million years ago. 



Mr. Walter Heape, F.R.S. , showed a series of photo- 

 graphs, taken at the rate of from 500 to 5,000 per second. 

 _The breaking of a glass vacuum-tube by a hammer was 

 one example — the complete break-up taking only a 

 twentieth part of a second. The tube seemed to bulge 

 inward first at the point of impact, and then the part of 

 the tube opposite to that point bulged outwards, and 

 broke in a fine powder ; finally the process of destruction 

 extended all over the tube. A solid rubber ball was also 

 followed in its course from a gun to a steel target — a 

 process which, with the rebound, occupied only one-fortieth 

 of a second. It assumed the most complicated shapes 

 during its adventures — varying from a flat disk, when it 

 hit the target, to an egg with a flat base when it bounced 

 off. Intense illumination is essential for these experi- 

 ments — two searchlights were employed in one instance 

 — and the cinema machine was an immense erection, 

 operated by electricity. 



Much has been heard of late concerning the trans- 



plantation of the heads of water-beetles. Three speci- 

 mens of beetles thus treated were shown by JMr. H. Graham 

 Cannon — of the beetle Hydrophilus on which the head 

 of a separate species, Dytiscus, had been grafted. In one 

 case a dissection had been made, and it was shown that 

 the gullet of the composite creature which resulted was 

 continuous throughout. The further developments of 

 this new investigation will be awaited with great interest. 

 Skin grafting, bone grafting, and gland grafting have 

 been performed for many years with success ; but when 

 we remember that a successful grafting of a head on to 

 a new body involves the regeneration of nervous tissue — 

 or at least appears to involve it — we are in touch with 

 a really important question. It is well known that, in 

 the human body at all events, if the spinal column is cut 

 across there is never any regeneration. A nerve, on the 

 other hand, will regenerate, although, as far as we know, 

 there has never been a successful attempt to graft a nerve 

 from another species on to a severed nerve. 



A more intimate exhibit was that of the contents of a 

 crocodile's stomach, which was, in the words of the 

 catalogue, " a notorious inan-eater." It lived in Africa, 

 in the Tanganyika Territory, and its stomach contained 

 a number of human bones, several metal bracelets, a 

 bead necklace, and the quills of a porcupine. There 

 must be several disadvantages in being a crocodile ! 



The National Institute of Industrial Psychology, under 

 Dr. S. C. Myers, F.R.S., showed a number of examples of 

 research work. There were investigations on the effect 

 of improved illumination on the output of coal-miners, 

 and a series of tests wliich were designed to select indivi- 

 duals entering engineering trades for their most appro- 

 priate tasks. They consisted of strips of wood of various 

 sizes, which had to be grouped in pairs so as to make 

 strips of equal length, geometrical figures which together 

 made rectangles, and other more complicated devices. 

 The results of these tests were in many cases surprising 

 and valuable ; for example, it is seen that there is never 

 any relationship between accuracy of muscular control 

 and muscular strength ; moreover, the particular apti- 

 tudes discovered were independent of the general 

 intelligence of candidates as tested by an examination 

 in English. 



Our only regret is that such demonstrations as this of 

 the Royal Society are not open, more frequently, to the 

 general public. They go a long way towards stimulating 

 interest in the great advances of the present day. 



R. J. V. POLVERT.\FT. 



Reviews of Books 



The Nebular Hypothesis and Modern Cosmogony. By 

 J. H. Je.\ns, M.A., F.R.S. (Oxford : Clarendon 

 Press, 2s. 6d.) 



Those of us who read seldom give the attention to 

 lectures issued as pamphlets that is given to larger works 

 bound in cloth. Tliis is frequently a mistake. A 

 lecturer with an audience to face, and a subject to describe 



