574 



NATURE 



[June 30, 1921 



noidal coils of either solid or stranded wire. Con- 

 ditions producing the maximum value of L/R' for a 

 given length of wire of given diameter are deduced. 

 'Jhe observed inferiority of stranded wire coils as 

 •compared with solid wire coils at high frequencies 

 is due to the lack of internal spacing of the strands 

 of the coils making the best conditions unattainable. 

 — E. S. Bieler : The currents induced in a cable by 

 the passage of a mass of magnetic material over it. 

 The mass used is in the form of a spherical shell, and 

 the deflection of a critically damped galvanometer in 

 series with the cable is deduced. The results agree 

 -with those of experiments carried out in the laboratory 

 on a small scale. The theoretical results are used to 

 ■determine the law of variation of the galvanometer 

 with different factors, and the relation between the 

 galvanometer deflection and the E.M.F. which pro- 

 duces it.— Dr. G. Barlow and Dr. H. B. Keene : The 

 experimental analysis of sound in air and water : some 

 experiments towards a sound spectrum. The original 

 sound vibration gives rise to an electric current of 

 telephonic magnitude, which is analysed by a method 

 of periodic interruption. A motor-driven interrupter 

 with a range of interruption frequency from 3-2000/sec. 

 is placed in series with a Broca galvanometer in the 

 circuit containing the alternating current to be 

 analysed. The speed of the interrupter is then slowly 

 varied. When the interruptions synchronise with any 

 component of the current, the galvanometer giv^s a 

 steady deflection, the magnitude of which depends on 

 the phase diff'erence. Thus the amplitude of each com- 

 ponent may be determined, and at the same instant 

 the corresponding frequency is observed strobo- 

 scopically. Experiments were made (i) to test the 

 trustworthiness of the method by analysing alternating 

 currents containing known constituents ; (2) to analyse 

 different types of sound in air, using both carbon 

 microphone and magnetophone receivers ; (3) to analyst- 

 sounds in water. The variations of the sound 

 s|5ectrum with distance, depth, and direction are in- 

 vestigated, and the spectrum of a motor-driven boat 

 ]s obtained under various conditions. — Dr. G. Barlow : 

 The theory of the analysis of an electric current bv 

 periodic interruption. A mathematical treatment of 

 the method of periodic interruption used in the experi- 

 mental analysis of sounds described in the previous 

 paper is gfiven, with an explanation of the effects of 

 periodic interruption on the intensity and quality of 

 sounds heard in a telephone. 



Geological Society, June 8.— Mr. R. D. Oldham, 

 president, in the chair. — Dr. W. F. Hume : The rela- 

 tions of the northern Red Sea and its associated gulf- 

 areas to the "rift" theory. The areas specially con- 

 sidered are the northern portion of the Red Sea and 

 the "Clysmic Gulf" (from "Clysma," the Roman 

 name for Suez), defined as the district lying between 

 the fault-bounded ranges of Egypt and Sinai. Within 

 Its borders Miocene deposits are of wide distribu- 

 tion ; beyond them they are absent. The folds 

 Avithin this region are from north-west to south-east, 

 •outside it the trend is frequently almost at right 

 ■angles. A line prolonging the direction of the western 

 •coast of the Gulf of Akaba to the shores of Egypt 

 divides the Clvsmic Gulf from the Red Sea, the former 

 being one. of complicated fold-and-fracture effects, 

 while in the latter only fold effects have been ob- 

 served. It is concluded that the whole region under- 

 went extremely slow submergence, the negative move- 

 ments continuing from earlv Jurassic to late Cre- 

 taceous times. Emergence of new land probablv took 

 ■place near the close of the Eocene period. It is sug- 

 gested that the area was occupied by an anticline 

 plunging northwards in the Clysmic Gulf region, and 



NO. 2696, VOL. 107] 



that it was subject first to marine and then to sub- 

 aerial erosion. This formed part of the continent on 

 which grew the trees of the Petrified Forest, and on 

 which wandered animals such as the Arsinoitherium 

 and the earliest elephants. The continental period 

 was most marked during late Eocene and early 

 Miocene times, and the area dealt with here appears 

 to have become one of very varied ridge and depres- 

 sion. The whole region was slowly invaded by the 

 ancient Mediterranean during the Miocene and 

 Pliocene periods. The pre-existing ridges became 

 coral-reef centres and the intervening depressions 

 were filled up, first by land-derived deposits and 

 then by lagoon formations. The earliest of these 

 formations appear to have been of Schlier (Middle 

 Miocene) age. The whole region of the Clysmic Gulf 

 became folded and fractured. There is strong faulting 

 at the borders with the igneous hills, and fold-ranges 

 are of asymmetrical anticline type. Compression of 

 the area, with uplift of portions, offers the best solu- 

 tion for the fact observed. Dislocation so marked and 

 so widespread could scarcely arise under rift forma- 

 tion as defined by Prof. J. W. Gregory, nor can the 

 whole of the surface-differences be ascribed to erosion. 

 No simple solution of the problem can be offered on 

 the evidence at present available, especially in view 

 of the fact that no important faulting has been noted 

 on the western borders of the Red Sea. The portion 

 of the Nile Valley about latitude 26° N., where fault- 

 ing is most conspicuous, may have been initiated by 

 erosion of a sharp anticlinal fold due to the compres- 

 sion of almost horizontal strata. .Sharp folds exist 

 in the desert east of the Nile, but their origin is 

 doubtful. 



Physical Society, June 10.— Dr. C. Chree, vice-presi- 

 dent, in the chair.— Sir Ernest Rutlierford : The stabilitv 

 of atoms. Traces of hydrogen and helium had been 

 found in discharge tubes believed to be initiallv free 

 from these gases; but it was impossible to establish 

 that no source of contamination was available. It is 

 necessary to attack the nucleus of the atom, and to do 

 this successfully requires extremely swift particles. 

 The effects produced when a-particles fired through 

 hydrogen collide with an atom were shown, and ex- 

 periments were described from which the conclusion 

 had been drawn that when an o-particle collides with a 

 nitrogen atom, a hydrogen atom is expelled from the 

 nucleus. The speed of these is in excess of what 

 can be obtained by collisions in hvdrog-en gasi itself, 

 so that the result must be due to the disintegration of 

 the nitrogen nucleus rather than to contamination 

 with hydrogen. Results on the disintegration of 

 aluminium and other elements were also indicated. 



Linnean Society, June 16. — Dr. A. Smith Woodward, 

 president, in the chair. — Prof. A. H. R. Buller : 

 The ocellus function of the subsporangial swelling of 

 Pilobolus. The subsporangial swelling of Pilobolus 

 functions as a squirting apparatus, and also as an 

 ocellus, which receives the heliotropic stimulus which 

 causes the stipe to turn the fungus gun towards the 

 light. The swelling is transparent and refracts light. 

 It appears to be the only orthoheliotropic plant organ 

 known which has a special light-perceiving' 

 cell-structure, which is sometimes described as a 

 simple eye. — Dr. N. Annandale : The vegetation of an 

 island in the Chilka Lake. The area of the island 

 is about one-third of a square mile, and the rocks 

 are comp>osed of garnet-bearing quartzite which yields 

 an infertile and scanty soil on weathering. The 

 climate is relatively dry. The vegetation consists 

 mainly of trees, shrubs, and perennial creepers, with 

 a great scarcity of herbs, ferns, and epiphytes, and a 

 complete absence of palms, bamboos, screw-pines, and 



