bluuebunny/crossref_metadata_2025 huggingface dataset:
The Distribution of Radio Brightness over the Solar Disk at a Wavelength of 21 Centimetres. II. The Quiet Sun ? One-dimensional Observations
Authors: Christiansen WN , Warburton JA
Published: May 2011

Daily records of one-dimensional distribution of radio brightness over the Sun are obtained in the way described in Part I of this series (Christiansen and Warburton 1953). When superimposed, these records show a well-marked lower envelope which remains substantially the same, in shape and size, over a period of months. This envelope gives the brightness distribution over the "quiet" Sun. The direction of scan, with respect to the position of. the solar axis, changes during a year by more than 50�. The very small change in shape of the envelope during this period suggests that for purposes of preliminary calculation the brightness distribution may be assumed to be circularly symmetrical. The radial distribution of brightness, calculated on this basis, is found to show marked limb-brightening and to be consistent with the calculated brightness distribution for a simple solar model in which the assumed values of temperature and density are close to those commonly accepted.
A High-resolution Aerial System of a New Type
Authors: Mills BY , Little AG
Published: May 2011

A method of constructing an aerial system of high resolution but small area and low cost is described. Its application to the production of narrow pencil beams at metre wavelengths for investigations in radio astronomy is discussed. A small-scale model has been constructed to test the principle.
Buoyant Motion in a Turbulent Environment
Authors: Priestley CHB
Published: May 2011

Solutions are given of the simultaneous equations for the vertical velocity and temperature of an element of fluid moving under buoyancy and subject to continuous mixing of heat and momentum with its environment. Three distinct modes of behaviour result: (A) ascent followed by damped oscillations, (B) asymptotic ascent to an equilibrium level, (C) absolute buoyancy in which the ascent rate increases indefinitely. For an environment in which the lapse rate is subadiabatic the motion is of type A for sufficiently large elements but may become B for the smaller elements; in super-adiabatic lapse rates the mode is C for sufficiently large elements, and B for the smaller elements, which are in no way unstable. The mode of motion is independent of the initial conditions but the scale of the motion is not.
The Structure of the F Region of the Ionosphere
Authors: Weiss AA
Published: May 2011

The effects of temperature cycles, of a decay coefficient non-uniform with height, and of vertical tidal drifts upon the structure of the F region of the ionosphere are considered. Special attention is devoted to the behaviour of the level at which the maximum electron density occurs.
Maxwell?Wagner Loss and Absorption Currents in Dielectrics
Authors: Hamon BV
Published: May 2011

The dielectric loss factors of a number of heterogeneous mixtures have been measured 'at frequencies up to 3 Mc/s. The mixtures consisted of a non-polar base material and small percentages of a slightly conducting solid or liquid "impurity".
Programme Design for the C.S.I.R.O. Mark I Computer. II. Programme Techniques
Authors: Pearcey T , Hill GW
Published: May 2011

The general structure of typical programmes is considered in relation to the structure of the computer, in particular to its facilities which tend to render programmes invariant with regard to their position in the store. Full-scale programmes are constructed by piecing together by a master programme a suitable selection of items from a library of "standard routines". The library contains "sub-routines" which are completely self-contained and require no additional information for their operation and are invariant with respect to their position in the store, and "routines" which are not so invariant and frequently require additional data to be provided during their entry into the store. The entry of special data for routines and the simplification of the construction of the master programme are facilitated by a special routine used whilst the entire programme is being entered into the store.
Efficiencies in the Method of Grouping
Authors: Guest PG
Published: May 2011

The efficiencies obtained in curve fitting by the method of grouping are discussed in terms of two parameters x2 x3 which specify the departure from uniform spacing. For polynomials of the first and second degree the efficiencies practically always exceed 0�7, but the efficiencies for the third degree polynomial may be less than this value if the spacing is markedly non-uniform.
Internal Conversion in the L-Subshells
Authors: Swan JB , Hill RD
Published: May 2011

The relative intensities of conversion-electron lines from the, three L-subshells have been determined for a number of ?-transitions, and the results compared with the theoretical values of Gellman, Griffith, and Stanley (1952). Experiment has been shown to be in accord with theory.
On the Reaction 23Na(p,g)24Mg and the Energy Levels of 24Mg
Authors: Turner OH
Published: May 2011

The energies of at least 20 ?-rays emitted from the 302 kV resonance level of 23Na(p,?)24Mg have been measured with sodium iodide crystals employed as (a) single crystal spectrometer, (b) scintillation pair spectrometer, (c) "cascade" spectrometer A tentative decay scheme involving levels at 1� 38, 4� 25, 5� 3, 5�8 or 6�2, 7�73, 8�57, 10�60,11�23,11�62, and 12�03 MeV is proposed for 24Mg. The effect of isotopic spin on the transition probabilities is discussed and some spin and parity assignments made. The resonance concerned has been determined as being at 302�2�0�6 kV, and is believed to be less than 50 V wide.
The Thermal and Electrical Conductivity of Copper at Low Temperatures
Authors: White GK
Published: May 2011

Measurements have been made of the thermal conductivity from 2 to 160 �K and the electrical conductivity from 1�4 to 293 �K of copper in strained and annealed states.
The Specific Heat and Thermal Conductivity of Graphite
Authors: Klemens PG
Published: May 2011

The specific heat of graphite is discussed in terms of a modified Debye treatment. It is shown that the contribution from the longitudinal waves varies as T3 below 45 �K, and as T2 at higher temperatures, whereas the usual two-dimensional treatment leads to a T2 variation at all low temperatures. Similarly the transverse contribution varies as T3 at lowest temperatures, But above 10 �K it varies as T2.
The Effect of Tension on the Thermoelectric Properties of Metals
Authors: Mortlock AJ
Published: May 2011

Measurements have been made on 11 different metals of the change in thermo-electric power accompanying elastic tensile strain. The measurements were made over the temperature range 20?400 �C on specimens of known purity. There is evidence that the magnitude of the general effect is dependent upon the purity of the specimen. The results obtained with gold differ considerably from those found by another observer.
Galactic Radiation at Radio Frequencies. V. The Sea Interferometer
Authors: Bolton JG , Slee OB
Published: May 2011

The factors involved in the study of discrete sources of galactic noise by the sea interferometer are discussed. Three new forms of sea interferometer which increase the effectiveness of this technique are described.
Flight Characteristics of Expansible Balloons
Authors: Darby JF , Hopper VD , E Laby Jean , Wilson ARW
Published: May 2011

A general study is made of the factors governing the flight of rubber balloons for cosmic ray research, and a brief account is given of the methods that have been used to obtain long exposures at great heights. The results of incidental upper air wind observations in Victoria over a period of 18 months are included.
Borehole Temperature Measuring Equipment and the Geothermal Flux in Tasmania
Authors: Newstead G , Beck A
Published: May 2011

An instrument, using a thermistor and an A.C. bridge circuit, is described by which temperature measurements in boreholes can be made to 0�01 �C. Results of temperature measurements in Tasmania are given and a value of 2 cal cm?2 sec?1 is obtained for the heat flux (uncorrected for recent glaciation).
The Influence of Meteoritic Dust on Rainfall
Authors: Bowen EG
Published: May 2011

A great deal of attention has been given in the meteorological literature to periodicities in the weather and to singularities in temperature or pressure, that is, occasions on which these quantities tend to have an abnormally high or an abnormally low value. The analysis of daily rainfall figures has not received as much attention, however, and it is the purpose of this note to point out some unexpected features in the rainfall occurring in different parts of the world and to advance a possible explanation for the phenomenon.
8Li(ß)8Be*(2a) Hammer Tracks in Photographic Emulsions
Authors: Wilson ARW
Published: May 2011

The a-pair energy spectrum of 94 8Li(�)8Be*(2a) hammer tracks observed in photographic emulsion and reported in the literature has been shown by Pickup and Voyvodic (1950) to agree with the results of Bonner et al. (1948), and Bennett, Bonner, Mandeville, and Watt (unpublished data 1948, see Bonner et al. 1948), who used cloud chambers to measure the pair energy spectrum up to about 10 MeV.
An Interpretation of the Field Tensor in the Unified Field Theory
Authors: Taylor NW
Published: May 2011

It is assumed that the skew symmetric part of the field tensor gik is a complex, self-dual tensor. This permits the whole set of field equations for free space to be derived directly from the theory without the introduction of an electric current density tensor. However, with this assumption it appears impossible for spherically symmetric electric and magnetic fields to exist in free space.
Twisted Magnetic Fields in Conducting Fluids
Authors: Dungey JW , Loughhead RE
Published: May 2011

The formation of loops in the lines of force of a twisted magnetic field confined within a cylinder of radius R, first suggested by AIfv�n (1950a), is discussed by the method of normal modes. The model first becomes unstable with respect to modes which do not lead to the formation of loops. Ignoring this, the condition obtained for loop formation is that the pitch of the twisted field be less than pR.
Space Charge Wave Amplification in a Shock Front and the Fine Structure of Solar Radio Noise
Authors: K Sen Hari
Published: May 2011

The Mott-Smith (1951) interpolation method gives a non-Maxwellian velocity distribution for the particles in a shock front. The dispersion equation corresponding to the non-Maxwellian distribution is derived by Vlasov's (1945) formula. The roots of the dispersion equation indicate frequency bandwidths of space charge wave amplification that decrease with the shock strength. It is suggested, in agreement with Denisse and Rocard (1951), that the storm bursts of narrow bandwidth originating in shock fronts constitute the elementary fine-structure components of solar radio noise bursts.
Galactic Radiation at Radio Frequencies. VII. Discrete Sources with Large Angular Widths
Authors: Bolton JG , Westfold KC , Stanley GJ , Slee OB
Published: May 2011

Observations with three forms of equipment have revealed the existence of a number of sources of angular width more than 1�.
Galactic Radiation at Radio Frequencies. VIII. Discrete Sources at 100 Mc/s Between Declinations +50° and ?50°
Authors: Bolton JG , Stanley GJ , Slee OB
Published: May 2011

One hundred and four discrete sources have been found from a survey covering declinations +50 to ?50�. The individual sources are compared in position and flux density with those of previous surveys. The observed distribution shows the concentration of sources of all brightnesses to the galactic equator found by Brown and Hazard (1953) and the concentration of the bright sources to the equator found by Mills (1952a, 1952b, 1952c).
Vertical Heat Transfer from Impressed Temperature Fluctuations
Authors: Priestley CHB
Published: May 2011

The ability of buoyant elements to carry heat upwards through a stably stratified fluid depends on their rate of mixing and hence on their size. The largest and smallest elements are both relatively ineffective and there exists an optimum intermediate size yielding a maximum value of the buoyant heat flux for a given intensity of temperature disturbance.
Deviations from Matthiessen's Rule for Cold - Drawn Wires
Authors: Ogilvie GJ , Clothier WK
Published: May 2011

An A.C. bridge method of high accuracy has been developed to measure deviations from Matthiessen's rule. Deviations have been shown to exist in cold-drawn wires of copper, aluminium, bronze, and 80/20 brass.
The Multiple Scattering of Electrons and Positrons
Authors: Mohr CBO , Tassie LJ
Published: May 2011

The angular distribution of the single scattering of 33, 121, and 1065 keV electrons at small angles in gold is calculated and compared with the distributions given by the Born approximation and by the WKB method as used by Moli�re. The single scattering distribution for 1065 keV electrons is integrated numerically to give mean square angles of multiple scattering, and these are compared with the values given by the various multiple scattering theories.
On the Choice of Glasses for Cemented Achromatic Aplanatic Doublets
Authors: Steel WH
Published: May 2011

It is shown that the types of glass given by tables for thin, low aperture telescope objectives of the "crown leading" doublet form are also those most suitable for thick, high aperture systems. The maximum focal lengths and the tolerances permissible in glass properties are given for each aperture, and the variation of these properties is considered when the thickness or wavelength of correction is changed, or the objective used with prisms.
The Barometer Coefficient and Air Mass Effects on Cosmic Rays at Macquarie Island
Authors: Jacklyn RM
Published: May 2011

The changes in cosmic ray intensity associated with the passage of weather fronts over the observing station have been investigated, using data from Macquarie Island. The effects can be explained in terms of the different way in which the height of the production layer for mesons varies with surface pressure for warm moist and cold dry air masses. The barometer coefficients found for these air masses are respectively ?0�120 � 0�058 per cent. per mb and ?0�220�0�041 per cent. per mb for the penetrating component. These results indicate that the frequently observed fluctuations in short-term barometer coefficients may be traceable to changes in air mass types.
An Investigation of Finite Strain in an Isotropic Material Subjected to Hydrostatic Pressure and its Seismological Applications
Authors: Keane A
Published: May 2011

An attempt is made to reduce the generality of the usual theories of finite strain and to concentrate on the case of hydrostatic pressure. The method used has been based on the works of Murnaghan (1951) and Birch (1952), and yields a general relation giving the elastic constants in terms of the strain and the derivatives of pressure with respect to strain.
On the Secular Variation of Rainfall at Adelaide
Authors: Cornish EA
Published: May 2011

A detailed analysis of the rainfall of Adelaide has established that periodic changes occur in the incidence and duration of the winter rains. These changes have a period and amplitude of approximately 23 years and 30 days respectively, and superimposed on them is a long-term trend which is manifested by protraction of the latter half of the season, spring rains now occurring about 3 weeks later than they did just over 100 years ago. The total quantity of rain precipitated has shown no statistically significant changes.
Comments on a Paper by E.G. Bowen Entitled ?The Influenoe of Meteoritic Dust on Rainfall?. 1
Authors: Swinbank WC
Published: May 2011

In a paper recently published in this Journal E. G. Bowen (1953) has proposed that meteoritic dust is an important factor in stimulating rainfall. This hypothesis is advanced as a result of a study of daily rainfall statistics .over a long period for Sydney and other places which reveal features, it is claimed,
Comments on a Paper by E.G. Bowen Entitled "The Influence of Meteoritic Dust on Rainfall". 2
Authors: Martyn DF
Published: May 2011

In this Journal Bowen (1953) has recently put forward evidence purporting to show that " there is a marked tendency for heavy falls of rain to occur on certain days rather than on others, and for this pattern to be repeated year after year". It is claimed that these days of heavy rain coincide (within a margin of variation of �2 days) in many parts of the world, and a theory is put forward explaining the supposed phenomenon in terms of world-wide concentrations of dust produced by the impact of known meteor showers on the atmosphere. He suggests that debris from these meteors, partially disintegrated by atmospheric friction at heights of about 100 km, filters down to the tropopause in about 29 days, where it activates or " seeds" rain clouds, so producing heavy rainfall.
Electron Screening and Thermonuclear Reactions
Authors: Salpeter EE
Published: May 2011

In the interior of stars most atoms are ionized, but the electrostatic potential of a bare nucleus induces a spherically symmetric polarization of the surrounding electrons and nuclei. The effect of this screening charge cloud on the rate of thermonuclear reactions is investigated for the case of complete ionization of all atoms.
The Influence of the Cathode Material on Measured Breakdown Strengths of Solid and Liquid Dielectrics
Authors: O'Dwyer JJ
Published: May 2011

An outline is given of a general method of accounting for the effect of electronic and ionic space charge in the breakdown of solid and liquid dielectrics. Detailed calculations are performed for a special model of both a liquid and a solid dielectric, and the results are compared with recent experimental work. Ex(tct calculation is not possible, but it is shown that for some substances an effect due to cathode material may well be measurable, and the factors influencing such an effect are examined.
The Residual Range of Delayed Particles in Extensive Air Showers
Authors: Officer VC , Eccles PJ
Published: May 2011

The arrival times of the penetrating particles of extensive air showers relative to that of the electrons have been studied by means of short reaction time Geiger counters. A 50 channel hodoscope has been used to identify the penetrating particles and measure their residual ranges where these lay between 15 and 30 cm of lead. From observations on 782 showers of median density 70 particles m-' in which a Penetrating component was detected, it was deduced that between 3 and 9 particles in 104 shower particles from showers of median density 28 particles m-', have delays <5 X 10-8 sec and are able to penetrate 15 em of lead. It follows that 81-94 per cent. of the delayed particles found by Jelley and Whitehouse (1953) without the use of absorbers, must be stopped by 15 cm of lead. This indicates a height of production below 0�8 km for at least half of these particles.
Harmonics in the Spectra of Solar Radio Disturbances
Authors: Wild JP , Murray JD , Rowe WC
Published: May 2011

The paper describes observations with a 40-240 McJs radio spectroscope leading to the discovery and preliminary investigation of harmonics in the spectra of sporadic bursts from the SWl. It is found that spectral features of bursts are commonly duplicated with a 2: 1 frequency separation. The ratio is sometimes appreciably lower though apparently never greater. This and other features of the spectra are shown to support the hypothesis that the fundamental frequency corresponds to the natural plasma frequency of the corona in the vicinity of the source. By applying this result to a standard model of the corona, information on the position, velocity, and size of the sources is deduced. The results suggest that the generation of bursts may be associated with longitudinal plasma oscillations excited by fast streams of charged particles.
Variations of Intensity of the Aurora at Macquarie Island
Authors: Jacka F
Published: May 2011

Observations of intensity of the aurora at Macquarie Island (geomagnetic co� ordinates 61 oS., 243�E.) are examined. The intensity is found to be dependent on geomagnetic planetary disturbance index Kp but the form of this dependence is different for different auroral forms. After eliminating the effects of variation of K p the residual diurnal and annual variations of intensity are small and irregular.
The Contribution of Phonons to the Thomson Coefficient
Authors: Klemens PG
Published: May 2011

An electric current of density j flowing in a temperature gradient \1T gives
up heat in a reversible way; the amount of heat thus liberated per unit volume
and unit time is given by
-p.j\1T, (1)
p. being the Thomson coefficient, which can be shown to be
T d r l(Kl )' p.=-e dT(P Ko -~ 5' (2)
where ~ is the Fermi energy, and the K's are the usual transport coefficients
as defined by Mott and Jones (1936, p. 306, equation (99)), or more generally
by Wilson (1953, p. 305).
The Multivariate t-Distribution Associated with a Set of Normal Sample Deviates
Authors: Coornish EA
Published: May 2011

This paper gives a short account of the more important properties of the multivariate t-distribution, which arises in association with a set of normal sample deviates.
The Angular Distribution of High Energy Electrons in Air Showers. I. Landau Approximation
Authors: Kalos MH , Blatt JM
Published: May 2011

The angular distribution of high energy (> 5 X 108 e V) electrons in air showers is calculated on a track length basis, using approximation A of Rossi and Greisen (1941) (no ionization loss) and the Landau (1940) multiple scattering approximation. We start with a discussion of the approximations used and an estimate of their validity. The basic equations are written down; qualitative results and very rough solutions are developed and applied to the Furry model of a cascade. For the Furry cascade the qualitative arguments lead directly to an Ansatz which yields an exact solution. In the actual cascade the corresponding Ansatz does not yield an exact solution. We then perform an iteration, employing a general method of Friedman. The final (iterated) solution is compared with the exact (in the Landau approximation) solution by means of their moments, and appears to be within 10 per cent. of the correct solution for E6fEs <l. Our solution compares well with earlier work on this problem. Appendices contain a short derivation of the angular moments, a general inversion formula for going from the distribution-in-projected-angle to the distribution-in-angle-with-the-showeraxis, and a derivation of the Friedman variation principle in vector space terminology.
The Emission of Radiation from Model Hydrogen Chromospheres. II.
Authors: Jefferies JT , Giovanelli RG
Published: May 2011

An improved method is presented for calculating the characteristics of the radiation field of Hoc, Loc, L[3, and the Lyman continuum emitted by model hydrogen atmospheres which are isothermal at one of a number of kinetic temperatures in the range 10' to 2�5 X 10' oK. It is found that earlier estimates of the intensities of these lines need revision and improved values have been obtained.
Aerial Smoothing in Radio Astronomy
Authors: Bracewell RN , Roberts JA
Published: May 2011

When an aerial is used to survey the distribution of radio brightness over the sky, the observed distribution is smoother than the true distribution; the broader the beam of the aerial, the greater the smoothing. It is shown that the aerial does not register those spatial Fourier components of the true distribution having frequencies beyond a cut-off determined by the aerial aperture. Components of lower frequency are registered but their relative strengths are altered.
Sea Surface Temperatures
Authors: Ball FK
Published: May 2011

The surface of the sea is losing heat by evaporation and by long-wave radiation exchange with the sky, both of these rates being of the order of 10-2 W cm-2 in clear weather. Heat lost in this way must be provided by conduction upward from the water beneath and downward from the air above. Short-wave radiation need not be considered since it is not absorbed at the surface. It seems possible therefore that on days of light wind the "skin" temperature of the sea might be appreciably less than the temperature of the layers beneath. Now sea surface temperatures are usually measured by means of a dip bucket and it is clear that water entering the bucket is derived in varying amounts from various depths below the surface, so that the temperature of the 'mixture will not generally be equal to the skin temperature of the sea. In view of these considerations an experiment was carried out with the object of determining the skin temperature by measuring the long-wave radiation emitted from the sea and comparing it with the dip bucket temperature.
The Sampling Distributions of Statistics Derived From the Multivariate t-Distribution
Authors: Cornish EA
Published: May 2011

The sampling distributions of the more important statistical derivates from the multivariate t-distribution are established.
Chord Construction for Correcting Aerial Smoothing
Authors: Bracewell RN
Published: May 2011

A graphical method is given for correcting the smoothing effect which arises when a celestial distribution of brightness temperature is scanned with an aerial beam. The method is much simpler to apply than previous methods which have been used and is no less accurate.
The Effects of Collimation and Oblique Incidence in Length Interferometers. I.
Authors: Bruce CF
Published: May 2011

An investigation has been made of the effects of position and size of diaphragm apertures on the interference fringes in length interferometry. The results indicate that, while the well-known correction formula for the effect of the oblique rays from a point source off the optic axis is always applicable, the effect of finite area of aperture is a more complex one and is not in general proportional to the length measured. This effect depends essentially on the phase differences arising from different points of the aperture and is oscillatory in character.
Theory of Tracks in Nuclear Research Emulsions
Authors: Blatt JM
Published: May 2011

The process of the formation of a visible track in a nuclear research emulsion is approximated by a simplified model which reduces it to a one-dimensional problem. Within this basic approximation, there are included many different detailed models, including all models so far proposed in the literature. We then consider the following quantities characteristic of the track : the number of gaps longer than some minimum length r contained in a cell length t of the track, nr(t) ; and the sum of the excess (over and above r) lengths of these nr gaps, xr(t).
The Influence of Noise on Radar Meteor Observations
Authors: Ellyett CD , Fraser GJ
Published: May 2011

An experimental investigation has been made of the minimum detectable echo power from meteor trails, using radar techniques at 69 Mc/s, with incoherent detection.
Note on Plasma?Electron Oscillations
Authors: Emeleus KG , Allen TK
Published: May 2011

Wild, Murray, and Rowe (1954) have recently presented strong evidence that coronal plasma oscillations are responsible for certain forms of solar radio noise. It may be of interest in this connexion to mention briefly some results, partly new, which we have obtained in a laboratory study of plasma oscillations. The interpretation of the experiments is not in all respects unambiguous, and we have not attempted any quantitative sealing from discharge tube to solar conditions?nor to the apparently allied problem of colliding nebulae?but there is at least some parallelism between the phenomena probably occurring in the different sources.
Excitation Studies of Reactions Occurring in the Proton Bombardment of 10B
Authors: Wignall JWG
Published: May 2011

This note reports an investigation of the excitation functions for the reactions 10B(p,?)11C and 10B(p,a)7Be for proton energies of up to 775 keV. Curran, Dee, and Petr?�lka (1939) investigated the (p,?) reaction by analysing the decay curve of activations produced in the bombardment of a thick boron target by 960 ke V protons ; they found no evidence for this reaction and quoted an upper limit of 10?13 11C nuclei formed per incident proton.
Hydromagnetic Stability of a Current Layer
Authors: Loughhead RE
Published: May 2011

The hydromagnetic stability of a uniform current flowing along a magnetic field and confined within a pair of parallel planes is discussed by the method of normal modes. The condition for marginal stability is derived and discussed with reference to two special cases.
Correcting for Running Means by Successive Substitutions
Authors: Bracewell RN
Published: May 2011

The paper discusses a practical procedure which compensates for the effect of taking running means, and a numerical example is worked out. The procedure simply requires the evaluation of further running means and should prove readily applicable in many cases where the need arises. In this procedure, which has already gained importance in more general form in other fields (as the method of successive substitutions), a criterion of convergence has been given ; and it is a major aim of the paper to illustrate, using running means as an instance, that the utility of the method of successive substitutions is wider than is indicated by this criterion.
Galactic Survey at 400 Mc/s Between Declinations ?17° and ?49°
Authors: Jefferies JT
Published: May 2011

The zone of the sky between declinations ?17� and ?49� was surveyed with a pencil-beam aerial. The operating frequency was 400. Mc/s and the aerial beam width 2� between half-power points.
Eigen Oscillations of Compressible, Ionized Fluids
Authors: Loughhead RE
Published: May 2011

The frequencies of eigen oscillations of regions of uniform magnetic field may be derived very simply from the hydromagnetic equations for a compressible fluid of infinite electrical conductivity in the cases where the regions are bounded by cylindrical and plane-parallel surfaces.
The Diffusion of Slow Electrons in Deuterium
Authors: IH Hall Barbara
Published: May 2011

The agitational energies and drift velocities of slow electrons diffusing in deuterium are measured as a function of the ratio Z/p of the electric field strength Z to the gas pressure p. The lateral spread of the diffusing electron stream is measured, which enables Townsend's energy coefficient to be calculated. Drift velocities are measured using a magnetic deflection method. On the basis of the kinetic theory of gases these measurements are used to calculate values for the mean free path L of the electrons at unit pressure, the mean proportion η of the energy lost by an electron in a collision with a deuterium molecule, and the collisional cross section A of the molecules in collisions with the electrons. The values obtained are compared with those of Crompton and Sutton (1952) for hydrogen.
Apparent Intensity Variations of the Radio Source Hydra?A
Authors: Slee OB
Published: May 2011

This paper describes the results of a detailed study of the flux density of the discrete radio source, Hydra-A. Over a period of 12 months, approximately 200 measurements of the Hydra-A intensity were compared with a similar number of observations on other strong sources. It was concluded that the observed flux density of Hydra-A is much more variable than that of these other sources, although no periodic changes have yet been detected. Possible mechanisms for the observed intensity changes are discussed.
Rotation and Other Motions of the Magellanic Clouds from Radio Observations
Authors: Kerr FJ , de Vaucouleurs G
Published: May 2011

The radial velocities measured in a survey of the 21 cm line from the Magellanic Clouds are discussed, principally in terms of the median velocity for each line profile. It is shown that each Cloud is rotating, and the analysis confirms the view, based on optical evidence, that the Clouds are flattened and tilted systems. The gas is probably the least flattened constituent of each Cloud and shows a large decrease of rotational speed with increasing distance from the equatorial plane.
Some Observations of Wind Velocity Autocorrelations in the Lowest Layers of the Atmosphere
Authors: Taylor RJ
Published: May 2011

From wind velocity observations in the lowest layers of the atmosphere, mean square velocity differences over a time interval at a point fixed in space are derived and their variation with the time interval is considered. The magnitude of these mean square differences is related to the rate of viscous dissipation of energy and to the shearing stress. On the average, fair agreement with predictions from the dimensional arguments of the theory of local isotropy is shown even though the results pertain to eddy sizes outside. the inertial subrange as usually defined.
Dispersal of Dust Particles from Elevated Sources
Authors: Csanady GT
Published: May 2011

The equations of Sutton for the atmospheric diffusion of gaseous pollutants are extended to the case of particles of appreciable free falling velocity with the boundary condition that dust fall rate equals ground level concentration times free falling velocity. It is shown that the effect of gravitational settling can be allowed for by (a) substituting the height above ground of the downward deflected plume axis for chimney height and (b) by introducing a factor a(x,z) as a multiplier to the "reflection" term in Sutton's equation.
The Diffusion of Electrons in a Gas at Low Temperatures
Authors: IH Hall Barbara
Published: May 2011

In the absence of an electric field, the state of motion of electrons moving freely among molecules of a gas is one in which the mean energy of agitation Q of an electron is the same as that, Q0, of a molecule of the gas. It is known, however, that in the presence of an applied uniform electric field Z the steady state of motion is one in which Q exceed's Q0, and, for a constant gas temperature, Q is a function of Z/n where n is the number of gas molecules in unit volume. Usually the measurements are made at room temperature, generally taken as 288�K, and it is convenient to replace Z/n by Z/p where p is the pressure of the gas in millimetres of mercury. It is of interest, however (Crompton, Huxley, and Sutton 1953), to investigate how the dependence of Q upon Z/n is influenced by the temperature of the gas itself, that is to say, by Q0. If the dependence of Q upon both Z/n and Q0 be expressed by some formula Q = f(Z/n, Q0), then all that is known with certainty about the function f is that when Z/n = 0, Q = Q0. In view of the absence of any theoretical guidance concerning the dependence of Q upon both Z/n = 0 and Q0, it was decided to investigate the matter experimentally in two simple diatomic gases, nitrogen and hydrogen.
An Unusual Electron Shower
Authors: Lim YK
Published: May 2011

Figure 1 depicts an event observed in a 600 � glass-backed Ilford G5 emulsion. The shower occurred at point 0 as indicated by a sudden increase in grain density of the incident track. For the first 150 � from 0 the grain density of all secondary tracks (which are not separated) is 46 �4 grains per 50 (�, approximately 3�5 times the plateau value (13�0 grains/50 �). 200 � from 0 five tracks are resolved and the sum of their grain densities is 64 � 2 grains/50 �, approximately five times plateau. These values suggest that one track originated some 150?200 � from 0, although the possibility that it originated at 0 is not entirely excluded.
Conduction of Heat in an Infinite Region Bounded Internally by a Circular Cylinder of a Perfect Conductor
Authors: Jaeger JC
Published: May 2011

Numerical information is given for radial flow of heat in an infinite region bounded
internally by a circular cylinder of radius a containing a perfect conductor, there being
contact resistance IIH per unit area across the cylinder. Problems considered are:
(i) the perfect conductor and the surrounding region initially at different temperatures;
(ii) heat supply to the perfect conductor.
The Heat Capacity of Copper Below 4?2 °K
Authors: Rayne JA
Published: May 2011

The heat capacity of copper has been measured below 4?2 �K with a calorimeter using a mechanical heat switch. The effects of changes in the chemical and physical state of the copper have been investigated with a view to understanding discrepancies between the results of previous workers.
Emission Nebulae as Radio Sources
Authors: Mills BY , Little AG , Sheridan KV
Published: May 2011

Attempts have been made to detect 14 bright emission nebulae at a wavelength of 3?5 m using a pencil-beam radio telescope with a beamwidth of 50 min of arc. Of these nebulae, six were probably observed in emission, seven were undetectable, and one, NGC 6357, was observed in absorption; radio isophotes were obtained for NGC 2237 and NGC 3372. Radio and optical data have been combined to estimate electron densities, masses, and sometimes the electron temperature of many of the nebulae. Values range from an electron density of 3 cm?3 and a mass of 3�10. solar masses for the outer regions of the 30 Doradus complex to an average electron density of 500 cm?3 and a mass of 20 solar masses for the Orion Nebula. Temperatures generally appear to be in the neighbourhood of 10,000 �K, except in the case of NGC 6357, for which 6500 �K is estimated.
Sporadic E at Brisbane
Authors: Thomas JA
Published: May 2011

Further data are presented in support of McNicol and Gipps's classification of two types of sporadic E at Brisbane (lat. 27?5 �S.), namely, sequential type (Ess) and constant-height type (Esc).
The Measurement of the Thermal Conductivities of Rocks by Observations in Boreholes
Authors: Beck A , Jaeger JC , Newstead G
Published: May 2011

The various possible methods of measuring thermal conductivity by observations in a borehole are discussed in the light of practical considerations. Three designs of measuring head are described and methods of reducing the observations are given. The possibility of obtaining results by heating a considerable length of a borehole is discussed.
On the Association of Solar Radio Emission and Solar Prominences
Authors: Wild JP , Zirin H
Published: May 2011

Prominence cinematograms made at Sacramento Peak and climax in the years 1949?55 have been examined and compared with the solar radio records at 167 Mc/s. No close connexion was found between limb events and radio events, but some eruptions were found to be associated with simultaneous radio bursts. Three such cases are discussed in detail.
Ionospheric Reflections from Heights Below the E Region
Authors: Gregory JB
Published: May 2011

The pulse method of radio sounding has been used at 1.75 Mc/s to detect low ionospheric regions whose voltage reflection coefficient exceeds 4 � 10?6. Observations from February to July 1955 have revealed reflections, from 95 km vertical height and of day-time occurrence only, which are believed to originate in the lower E region. A region with a lower boundary predominantly at 85 km has been found to exist continuously, and previous suggestions as to its meteor origin are queried. A series of complex partial reflections have been detected during day-time only down to 53 km, with significant heights near 75, 67, and 55 km. The occurrence and strength of these lower reflections increases markedly during winter.
The Theory of Strong Katabatic Winds
Authors: Ball FK
Published: May 2011

In regions where strong katabatic winds occur, notably Commonwealth Bay, Antarctica, there is often a sharp boundary between the strong winds and the comparatively calm conditions at sea. The seaward movement of this boundary across a coastal station is accompanied by a sudden onset of strong winds and the landward movement by their sudden cessation. The boundary has all the characteristics of a pressure jump line accompanying a sudden change in depth of the cold air. Further-more, it is to be expected from theoretical considerations that a pressure jump will occur near the coast. A simple theory is developed from which various characteristics of the flow can be predicted, including the intensity of the jump and the deviation of the wind from the lines of greatest slope caused by the Earth's rotation. These predictions agree moderately well with observations.
The Thermal Expansion of a Grossularite Garnet
Authors: Wilson LG
Published: May 2011

A study of the thermal behaviour of the lattice constant of a grossularite garnet in terms of thermal expansion has been made using a 10�302 cm diameter high temperature back reflection symmetrical processing X-ray camera designed by G. B. Clarke (1951) for the measurement of mineral lattice constants at high temperature.
A Model of Nuclear Shape Oscillations for g?Transitions and Electron Excitation
Authors: Tassie LJ
Published: May 2011

A model of nuclear shape oscillations is set up for an arbitrary nuclear charge distribution. For a uniform charge distribution the model reduces to the liquid drop model. The model is used to consider ?-transitions and electron excitation of nuclei. Explicit expressions are obtained for four charge distributions: (a) uniform, (b) Gaussian, (c) exponential, (d) uniform with Gaussian "edge". The theory predicts a relative angular distribution of electrons scattered by the 4�43 MeV level of 12C in agreement with the experimental results of Fregeau and Hofstadter (1955), but gives a scattered intensity seven times too large.
Calculation of Activation Energies from Calorimetric Work Carried Out at a Constant Rate of Heating
Authors: Nicholas JF
Published: May 2011

Some recovery processes in metals occur at temperatures too high to be readily accessible to isothermal calorimetric studies and such phenomena are more conveniently investigated using a constant rate of heating. It is shown that the activation energies of these processes can be determined from calorimetric work carried out at a constant rate of heating.
Neutron Experiments with a Sensitive Szilard?Chalmers Detector
Authors: Edge RD
Published: May 2011

The Szilard-Chalmers reaction has been developed as a sensitive detector for the comparison of neutrons from sources of different primary energy and angular distribution. Using sodium permanganate solution, a detection efficiency of approximately 7 per cent. for all neutrons in the energy range 0?5 MeV was obtained and high accuracy achieved.
The Behaviour of a Chapman Layer in the Night F2 Region of the Ionosphere, Under the Influence of Gravity, Diffusion, and Attachment
Authors: Duncan RA
Published: May 2011

It is shown that, in the presence of diffusion, gravity, and attachment, a Chapman layer, no matter what its height, maintains its shape, decaying uniformly with an effective attachment coefficient equal to the true attachment coefficient at the height of the electron density maximum; and that, at the same time, the layer drifts bodily towards an equilibrium height.
Radio Echo Observations of Meteor Activity in the Southern Hemisphere
Authors: Ellyett CD , Keay CSL
Published: May 2011

A further analysis has been made of 32,000 meteor echoes obtained during 1953 by radar apparatus operating at a frequency of 69 Mc/s. Monthly and annual mean diurnal rate curves have been drawn, revealing a strong similarity between southern and northern hemisphere results. It is concluded that most meteoric matter incident on the southern hemisphere, down to magnitude +4�5, is confined to direct orbits closely following the plane of the ecliptic.
A Survey of Cosmic Radio Emission at 600 Mc/s
Authors: Piddington JH , Trent GH
Published: May 2011

The results are given of a survey of cosmic radio emission at 600 Mc/s between declinations 90 �S. and 51 �N. using a 3��3 wide beam. Isophotes are plotted in a system of celestial coordinates (epoch 1955).
An Investigation of the Radio Source 06N2A in Gemini
Authors: Rishbeth H
Published: May 2011

A lunar occultation of the radio source 06N2A in Gemini was observed in the course of an investigation at a wavelength of 3�5 m, for which the "Mills Cross" aerial was employed. During the occultation the intensity of the source was reduced by over one-fifth, although less than one-tenth of the associated galactic nebulosity IC 443 was obscured. The radio source appears to resemble the nebula, and the relation between them is discussed with the aid of simple geometrical models of the source.
The Electronic Heat Capacity of a Copper?3 Per Cent Zinc Alloy
Authors: Rayne JA , Kemp WRG
Published: May 2011

Recent measurements on a copper-1 per cent. cadmium alloy (Rayne 1956) have shown that its electronic heat capacity differs considerably from that of pure copper. For the alloy
Recurrence Formulae for the Reflectance And Transmittance of Multilayer Films with Applications
Authors: Godfrey GH
Published: May 2011

Formulae are developed which, by repeated application, give the changes in amplitude and phase when light passes normally through any number of layers of homogeneous absorbing or transparent materials. These formulae are suitable for numerical computation and provide a direct route to the analytical expressions for the reflectance and transmittance in particular cases. Special attention is given to the case in which the layers are a quarter wave or multiples of a quarter wave in thickness.
The Measurement of the Drift Velocity of Electrons Through Gases by the Electron Shutter Method
Authors: Duncan RA
Published: May 2011

The behaviour of an electron shutter apparatus such as that used by Neilsen and Bradbury for the measurement of electron velocities is analysed, taking into account the effect of electron diffusion. A relation between shutter frequency and drift velocity, and a relation giving the accuracy obtainable by the method in terms of the chamber length and gas pressure are derived. It is thus shown that neglect of the influence of diffusion can lead to large errors, but that these can be reduced to any desired degree by increasing the chamber length or the gas pressure. Numerical examples are given.
A Study of "Spread?F" Ionospheric Echoes at Night at Brisbane. III. Frequency Spreading
Authors: Singleton DG
Published: May 2011

Virtual range versus frequency (P'f) records of the ionosphere made at Brisbane (lat. 27�5 �S., long. 152�9 �E.) during 1952 and 1953 have been examined. It is found that occasionally neither the o nor the x mode of propagation penetrates the F2 layer at a unique frequency, the upward sweeping traces either being blurred out over a range of penetration frequencies (diffuseness) or possessing a fine structure (penetration-frequency multiplicity). Temporal analysis of the occurrence of these. effects reveals that they occur only at night; penetration-frequency multiplicity appearing more frequently in the hours before dawn, while the diurnal distribution of diffuseness has a maximum between 0100 and 0500 hr in summer and represents a more even distribution between 2100 and 0500 hr in winter. The seasonal distribution has a pronounced peak in the winter months and minima in the equinoctial months. These data are compared with the world-wide picture of these variations as it has emerged from the recent literature.
A Least Squares Solution of Linear Equations with Coefficients Subject to a Special Type of Error
Authors: Mackenzie JK
Published: May 2011

Following the classical method a least squares solution is given for the equations where the ark and brk are fixed known constants and the er are observed values subject to error. The solution is obtained as a series in the successive moments of the joint distribution of the er, and only terms up to those involving the variance are retained. In this approximation the estimated values of the xk are biased, but, after correction for this bias and using a particular weight for each equation, the classical tests of significance for the case brk = 0 can be applied unchanged. With suitable assumptions it is shown that the series converges more and more rapidly as n ? 8 for almost all sequences of the er