December 9, 1909J 



NATURE 



177 



the fuel available. The coal that was obtainable was of 

 so unsuitable a quality that, after experiments with it whole 

 and pulverised, none of which was attended with success, 

 recourse was had to oil fuel. A feature of the smelting 

 operation is the relatively large proportion of flue dust 

 treated. Full details are given of the quantities of 

 materials treated and of the costs of the various operations, 

 and the author goes minutely into the circumstances attend- 

 ing the failure of the coal-firing and difficulties encountered 

 during that and the subsequent oil-firing. The paper is 

 principally composed of observed facts. 



Physical Society, November 26. — Dr. C. Chree, F. R.S., 

 president, in the chair. — Dr. J. W. Nicholson : The 

 effective resistance and inductance of a helical coil. This 

 paper deals with a determination of the effective resistance 

 and inductance of a helical coil of great length, composed 

 of thin wire, wound on a cylinder the radius of which is 

 large in comparison with that of the wire. The pitch of 

 the winding is not small, so that the problem cannot be 

 treated by the method of Cohen. The method employed 

 depends upon the use of a type of " helical coordinates " 

 defining the position of any point, and of the general 

 theorem relating to orthogonal systems of coordinates. A 

 solution is obtained for the internal and external forces, 

 corresponding to a given impressed electromotive force, in 

 the form of a Foujier series of which only the initial 

 terms require calculation. The value of the effective 

 current across any section is obtained, and thence the 

 inductance and resistance. For a high frequency it is 

 found that the change of self-inductance due to twisting 

 of the wire tends to vanish, and that the change of resist- 

 ance tends towards a value independent of the frequency. 

 — W. A. Scoble : Ductile materials under combined stress. 

 The author further considers the results from some earlier 

 tests made on mild steel bars, £-inch diameter and 30 inches 

 effective length, under combined bending and torsion. It 

 is pointed out that the yield-point is usually selected as 

 the criterion of strength, because it is more easily deter- 

 mined than the elastic limit, it is less affected by special 

 treatment of the material, and it is assumed that the 

 failure of Hooke's law between the elastic limit and the 

 yield-point is due to local yielding. The elastic limit is 

 the correct point, and is used throughout, because the 

 intermediate state mentioned above does not appear in 

 bending. The results of tests on steel and copper tubes 

 under combined bending and torsion are also given. All 

 the results indicate that the maximum stress and maximum 

 strain laws do not apply to ductile materials. The stress 

 difference or shear stress law is approximately true, but 

 there is, in each case, a deviation from the law which is 

 opposed to the other theories mentioned. The shear stress 

 law appears to state the average behaviour of ductile 

 materials, but there are considerable deviations from the 

 law, which are usually opposed to the other theories. 

 Other tests by the author indicate that brittle materials 

 obey the maximum stress law, and it is therefore suggested 

 that the value of. " m " depends chiefly on the degree of 

 ductility of the material considered, and to a lesser extent 

 on the system of loading. — Drs. W. Makower and 

 S. Russ : The recoil of radium C from radium B. It 

 has been shown in a previous paper that, during a radio- 

 active transformation involving the expulsion of an a 

 particle, the residue of the atom from which the a particle 

 has been expelled recoils in an opposite direction to that 

 in which the a particle is emitted, and can travel a con- 

 siderable distance through a gas if the pressure is 

 sufficiently low. A similar effect was also demonstrable in 

 the case of the transformation of radium B into radium C, 

 although this transformation is supposed to be accom- 

 panied by only j3 rays. The phenomena associated with 

 this recoil are studied in this paper. In the first place, it 

 was found that it was only in certain circumstances that 

 pure radium C free from radium B was projected from a 

 plate coated with radium B and radium C. Secondly, the 

 active deposit on a plate appears to be concentrated into 

 heaps, so that radium C, in breaking up, mechanically 

 carries with it some radium B. If, however, sufficient 

 time is allowed after removing a plate from the emanation 

 for Radium A to decay completely, and if, further, 

 sufficiently small quantities of deposit are used to avoid 

 NO. 2093, VOL. 82] 



the formation of heaps, practically pure radium C is 

 emitted. The law according to which the radiation fell off 

 with distance was also studied, and it was found that 

 radium C is not emitted from an active plate equally in 

 all directions, a greater quantity being emitted normally 

 to the plate than in directions making an angle with the 

 normal. The absorption by air of radium C when it 

 recoils from radium B was investigated. It was found 

 that about half the radium C projected from a plate was 

 stopped by 2-5 cm. of air at a pressure of 004 mm. 

 mercury. Since radium B emits only ;8 particles, the 

 energy of recoil in this case should be less than one- 

 millionth of the energy of recoil in a transformation in 

 which an a particle is emitted. The fact that the penetra- 

 tion of radium C when it recoils is as much as one-fortieth 

 of that previously found for radium A and radium B is 

 therefore surprising. — Dr. C. V. Burton : The sun's 

 motion with respect to the rether. Notwithstanding the 

 well-known " principle of relativity," it is theoretically 

 possible to determine the motion of the solar system with 

 respect to the jether from observations of the eclipses of 

 Jupiter's satellites, and the possibility was indicated by 

 Maxwell some thirty years ago. For convenience, the 

 motion of the aether with respect to the sun may be called 

 a wind, and the method proposed is based on the con- 

 sideration that the tidings of an eclipse will travel towards 

 us more rapidly when the Jovian system is to windward 

 of us than when it is to leeward. The residual dis- 

 crepancies between the observed and calculated times of 

 eclipses have to be analysed for systematic differences 

 depending on the direction in space of the straight line 

 drawn from the earth to Jupiter, and formulje are given 

 for finding by the method of least squares the most prob- 

 able values of a, b,, c,, the components of the sun's velocity 

 with respect to the aether. The material available is to 

 be found in Prof. R. A. Sampson's discussion of the 

 Harvard photometric eclipse observations, about 330 

 eclipses of Jupiter's satellite I. being included. In order 

 to obtain a preliminary notion of the accuracy to be ex- 

 pected, a simplified system has been considered in which 

 (for one thing) the eccentricity of the orbits was virtually 

 neglected, and it appears that some advantage is to be 

 gained by taking the plane of Jupiter's orbit, rather than 

 the ecliptic, as one of the coordinate planes. The axis of 

 K is drawn from the sun's centre through the node of 

 Jupiter's orbit, the axis of y lying also in that orbit, and 

 the axis of c being perpendicular thereto. Taking 4-5 

 seconds as the " probable " discrepancy between theory 

 and observation for a single eclipse, the following pre- 

 liminary estimates are obtained : — probable error in a = 

 43-6 km. per second; orobable error in 61 = 45.6 km. per 

 second; probable error in C; = 10,000 km. per second. 



Royal Anthropological Institute, November 30. — Dr. 

 A. C. Haddon, F.R.S., in the chair. — Canon Greenwell 

 and the Rev. R. A. Gatty : Pit-dwellings at Holderness. 

 An interesting discovery of pit-dwellings has been made 

 by Mr. William Morfitt, of Atwick, near Hornsea, in 

 Holderness. Mr. Morfitt for the past twenty years has 

 devoted his attention to these dwellings, which are 

 excavated 5 feet deep in the Boulder-clay, and are covered 

 by an unbroken surface soil to the depth of 18 inches. 

 The pits are filled with black mud, which on being re- 

 moved discloses the original floor of the dwelling, with 

 its hearth and broken pottery, the remains of past feasts 

 in the form of broken bones, and the rude flint tools of 

 the dwellers, for no well-shaped implement has come to 

 light. About thirty of these dwellings have been examined 

 and the pottery restored. Their great antiquity is proved 

 by the fact that long after the inhabitants had ceased to 

 occupy the pits, and mud had filled them up, a surface soil 

 had formed to the depth of 18 inches, upon which late 

 Neolithic implements and bronze implements have been 

 found. This shows the dwellers to have been earlier than 

 the Bronze age. The pottery is of the rudest kind, with no 

 decoration. The bones remaining from the feasts include 

 those of red deer, horse, Celtic ox, goat, and pig. Although 

 the pits are now close to the sea, no fish bones or shells 

 have been found in them, which proves that when they 

 were occupied their position was far inland. The rapid 



