February 21, 19 18] 



NATURE 



499 



Mihlimation, has given a similar growth of actinium. 

 (.1) The work was undertaken to test and confirm the 

 view that the parent of actinium occupies the eka- 

 tantalum place in the periodic table, ajid gives actinium 

 in an a-ray change of long period, itself being formed 

 as the product of uranium-Y, discovered by Antonoff, 

 wlio suggested that it was the first member of the 

 .'ictinium series. But this mode of origin of actinium, 

 tliough at present the most probable, is not yet conclu- 

 sively established to the exclusion of all the other pos- 

 sible modes of origin, discussed in the historical intro- 

 duction. — Prof. A. Schuster : Some problems in the 

 theory of radiation. This paper deals with the oscil- 

 latory energy taken up by a simple resonator under 

 the action of white light, and the translatory energy 

 imparted to a molecule by radiation. The first problem 

 has been treated by Planck. It is solved here in a 

 very simple manner, and the method used, wheh ap- 

 plied to the second problem, leads to the important 

 result that a molecule at rest, within an enclosure of 

 uniform temperature, will, while taking up an oscilla- 

 tory energy, be set in motion with an acceleration that 

 will increase its speed until the average energy reaches 

 a definite value. If the Rayleigh-Jeans laws of radia- 

 tion be assumed to hold, the ultimate average energy 

 due to radiation alone is two-thirds of that derived 

 from the kinetic theory of gases. — E. A. Owen : The 

 absorption of the radiation emitted by a palladium anti- 

 cathode in rhodium, palladium, and silver, (i) A short 

 account is given of some preliminary experiments car- 

 ried out with the rays from an ordinary X-ray bulb. 

 (2) A spectrum of the rays from a palladium anti- 

 cathode is obtained over a limited range of wave- 

 lengths by reflection in the (iii) face of a carborundum 

 n ystal. The spectrum shows that the bulb emits a 

 I ontinuous band of wave-lengths upon which are super- 

 f)()sed the characteristic rays of the metal of the anti- 

 ( athode, and under the conditions of working in this 

 particular case the relative intensities of the different 

 wave-lengths in the spectrum remained approximately 

 constant. (3) The "end radiation" of the bulb was 

 found to be verv homogeneous. (4) There is a minimum 

 of intensity in the spectrum corresponding with the wave- 

 length o-4q3 X 10-* cm. On the assumption that the 

 minimum is due to the selective absorption of this wave 

 in the crystal, the value 0-493x10-* cm. is assigned 

 to the /3 line of the J series of silicon. From the ex- 

 perimental results of Barkla and White on the J series 

 of the elements Al, C. and O, the approximate values 

 deduced for the ^ line of the J series of oxygen and 

 carbon are oj^iqxio-' cm. and 0-559x16-* cm. re- 

 spectively. (5) Assuming Bragg's mean value of the 

 a line of palladium to be 0-586 x 10-' cm., the follow- 

 ing values are obtained for the wave-lengths of the ^ 

 and V lines: ^ = 0-520x10-* cm.; 7 = 0-509x10-' cm. 

 (6) The absorption coefficients of the ravs from the bulb 

 have been measured in rhodium, palladium, and silver. 

 The results show that the relation between wave-leng^th 

 and absorption coefficient is expressed by the relation 

 T/e = KA', where r/e is the fluorescent coefficient and 

 IC is a constant for a given substance over the range 

 of wave-lengths between the absorption bands of that 

 substance. (7) The critical wave-length necessary to 

 excite the characteristic rays of a substance lies in the 

 neighbourhood of the ^ ray of that substance. The 

 a rav is not excited until the^ ray is excited, (8) It 

 is pointed out that the purity of the characteristic lines 

 emitted by a bulb and isolated by reflection at a crystal 

 face will depend, to a great extent, upon the state of 

 working of the bulb. 



Zoological Society, February 5.— Dr. A. Smith Wood- 

 ward, vice-president, in the chair.— Prof. B. L. Bhatia 

 and Baini Prasiiad : Skull of ^ana tigrina. Daud. — 

 NO. 2521, VOL. 100] 



G. A. Boulenger : Description of a new snake of the 

 genus Oligodon, from Upper Burma.— Dr. R. Broom : 

 Two rare South African golden moles. One specimen 

 was described as a new species of Bematiscus, B. 

 leschae. Hitherto the giant moles of the eastern Cape 

 Colony have been referred to B. trevelyani, but the 

 present type from St. Cuthbert's, Isolo, differs from 

 B. trevelyani and agrees with B. transvaalensis and B. 

 villosa in having the temporal bulla markedly project- 

 ing from the side of the skull. The other specimen 

 exhibited was one of the rare mole, Chrysochlorts 

 sclateri. Hitherto it has been only known from the 

 Nieuwveld and from Basutoland— localities 350 miles 

 apart. The present specimen was from New Bethesda, 

 130 miles nearer to Basutoland than the original 

 locality. 



Matliematical Society, February 14.— Prof. H. Hilton, 

 vice-president, in the chair.— Prof. A. C. Dixon : Note 

 on functional equations which are limiting forms of 

 integral equations.— Prof. D. M. Y. Sommervllle : The 

 singularities of trochoidal curves.— O. Hoppe : The 

 primality of (io^»-i) (second communication).— L. J. 

 Mordell : A statement by Fermat. 



Edinburgh. 

 Royal Society, January 14.— Dr. John Home, presi- 

 dent, in the chair.— Prof. R. A. Sampson : Notes on 

 the Coupar Angus meteorite. This meteorite, which 

 attracted much attention from its brilliancy before it 

 burst, fell on December 3, 19 17, and fragments were 

 found in Perthshire and Forfarshire. It is an aero- 

 lite or stony meteorite, but the detailed mineralogical 

 characters have not vet been given. It was estimated, 

 from the evidence o'f a number of witnesses, that it 

 began to blaze at a height of about twenty miles in 

 the atmosphere, probably above Coupar Angus. In 

 regard to the origin of such bodies, it was suggested 

 that thev might have been ejected in bygone ages from 

 lunar volcanoes, continuing to circulate since then be- 

 tween the earth and the moon in irregular orbits until 

 finally drawn down upon the earth.— Dr. C. G. Knott : 

 The propagation of earthquake waves through the 

 earth and connected problems. When a large earth- 

 quake occurs at any part of the earth elastic waves an 

 sent out in all directions through the earth, emerging 

 at the surface as disturbances which can be recorder' 

 on delicate seismometers. Up to about 120° from th. 

 epicentre, the times at which these variations emerge 

 i after the time of occurrence of the earthquake 

 i were first tabulated by J. Milne. The increasing num- 

 ! ber of observations and the improvement of the instru- 

 ' ments have led to the tabulation of more accurate data 

 1 than was possible in the earlier days. Following up 

 certain calculations made in iqo8. Dr. Knott, using 

 ' these more recent data, has made fresh calculations of 

 I the velocities of the seismic waves through the earth 

 \ by a mathematical method based on the theory of 

 integral equations and entirely free from assumptions. 

 As has long been recognised, two types of wave are 

 transmitted through the body of the earth known as 

 the primary (P) and the secondary (S) waves. The 

 broad results of the investigation may be stated thus :— 

 The velocity of the P wave increases steadily with 

 I depth from 4-46 miles (7- 18 kilometres) per second at 

 the surface to 6-2 miles (10 km.) per second at a depth 

 of 400 miles (650 km.), continuously increasing at a 

 slightly smaller rate of increase until it reaches 

 7.95 miles (12-8 km.) per second at a depth of 

 1000 miles (1600 km.), after which, at greater depths 

 the speed of propagation remains constant. The S 

 wave travels moreslowly than the P wave, but changes 

 in verv much the same wav. the values of the speed 

 being 2-47 miles (3-98 km.) per second at the surface. 



