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Th. licence--Droit--Paris, 1879-08-08.

A hot gas jet was produced by an Argon plasma torch and was played on a water cooled rotating cylinder mounted 30 mm above the nozzle of the torch. The power and gas flow rate to the torch were varied. A Mach-Zehnder interferometer was used to form the interference fringe shift patterns. A version of the Abel Transformation was used to derive radial temperature distribution results from collimated measurements of fringe shift along parallel chords at points long the axis of the jet. The axial temperatures of the jet were found to be between 800 K and-8000-K. No results were possible in the area of the jet close to the cool surface due to turbulence in the fringe pattern. Relationships between input conditions to the torch and the temperatures in the jet were sought but no conclusions could be drawn due-to the severe limitations found in the analysis. In the range of power, 1.3 to 3 kW, and flow rate, 1.4 to 4.3 1/min, supplied to the torch, the number of fringe shifts observed in the interferograms was small, usually less than 2.5, making the fitting of fringe shift curves to the experimental data points uncertain. Tests undertaken fitting different shaped curves to a sample set of data caused 50-100% variations in the resulting radial temperature distribution. Slight variations in the radius of the jet measured from the interferograms caused large changes in on-axis temperature, though the distribution-towards the outer edge of the jet was unaffected. A similar-phenomenon was observed by changing the number of iteration points used in the numerical analysis. Areas for further work are identified and discussed, in the thesis.

We present new, accurate astrophysical parameters for both components of the six short-period Algol-type binary stars RZ Cas, AT Peg, TX UMa, AF Gem, RU UMi and HU Tau. The accuracy of the astrophysical parameters is ensured by the determination of a mass ratio for each of the systems from the spectroscopic orbits of both components via the cross correlation technique. For RZ Cas and AT Peg we have developed a simple technique to correct the observed photometry for the presence of the secondary component. Spectral classification of the primary component of AT Peg was aided by the use of an improved Doppler tomography technique. The systems RZ Cas, AT Peg, TX UMa, AF Gem and HU Tau are found to be apparently normal semi-detached Algol-type systems and accurate masses and radii have been determined with a typical precision of a few percent. For RU UMi we have been able to confirm the suspected semi-detached configuration. We have compiled a list of nine Algol-type binary stars, five from this study, for which the observed astrophysical parameters have been determined accurately using a combination of both spectroscopic and photometric data in a self-consistent solution. The general model of non-conservative case B evolution adequately explains the properties of these systems as a group. Angular momentum loss via a magnetic stellar wind is shown to be an important factor in the evolution of these systems. However, there appear to be no published evolutionary models which can be used to estimate the properties of the progenitors of these systems. For the more massive systems the best available models predict periods that are too large by ~50-250% and luminosities for the faint components that are too high by factors of 10-20.

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Prolificacy in sheep, under most types of flock management, may exert an overwhelming influence on profitability. Three major classes of sheep farming are found in New Zealand, namely Extensive farming, on high country and droughty areas where wool is the chief product, Store sheep farming, on harder hill country, where income is derived from sales of both wool and surplus stock, and Fat lamb farming, in the easier and improved areas, where sales of fat stock almost exclusively dictate the size of the income. In all three types, ewe fertility is of paramount importance. This investigation was undertaken as a pilot attempt to demonstrate, with more accuracy, the source of, or reason for, the additional lambs which result from flushing ewes, in as far as this practice may increase both ovulation rate and subsequent mortality or merely reduce mortality in developing ova at some as yet underdefined stage of early pregnancy. The nature of the experiment was such that a study of the time-relationships of ovum loss and embryo mortality at various stages in early pregnancy could be made. Thus the matings of 225 ewes in two separate mobs were observed and slaughter dates were measured for individual ewes from mating times. By this means a considerable collection of both field and laboratory data was made available for a study of comparative individual and group reactions to the flushing treatment applied.

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