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This thesis contains an account of some of the work undertaken by the author while a member of the Astronomy Group at the University of Durham. The work of the group which involves the measurement of the amount of linear polarisation in nebular astronomical objects, is in collaboration with the Royal Greenwich Observatory. The initial chapters of the thesis describe the design and construction of the Durham Polarimeter which detects and measures the polarisation, and outlines the advantages of using a 4 cm McMullan electronographic camera as a recording device Initial alignment of the polarimcter components prior to observation and the procedures followed to obtain a series of electronographic plates are described along with the development of a series of reduction equations which link the polarisation parameters to the densities of the images on the electronographic plates. Electronographs of the irregular II galaxy, M82, which is the subject of study in this thesis are illustrated. In the later chapters of the thesis, the 1 education of the visual electronograplis to a digital form and the subsequent sophisticated computer programming required to accurately align the digital electronographs, lead out the densities for several thousand locations distributed over the lunge of the galaxy, and finally convert these densities to polarisation parameters is described. Comparison of the new polarisation map of 1182, with the previous photo-electric determinations confirms the success of this new automatic technique for the production of high resolution, accurate polarimetric measurements. In the final chapters of this thesis, M82 is reviewed chronologically, and the observational information on the galaxy is summarised. Finally, the present polarisation data is analysed using a recent model of the galaxy, and the result which are consistent with those previously determined are considered in conjunction with the mass of observational evidence concerning the evolution and morphology of the galaxy. The possibility that M82 may represent a connecting link in galactic evolution is tentatively proposed.

The design of the modification required to increase the angular resolution of the Haverah Park Magnet Spectrograph is described. It is shown that the reduction in uncertainty of angular measurement achieved by the modification is characterised by a standard deviation of 0.l6 , corresponding to a limit of momentum resolution of 120 GeV/c. The momentum spectra, of muons in EAS derired from the data available at the conclusion of the period of operation of the original spectrograph are presented. These spectra relate to muons falling between 150 m and 600 m from the cores of showers of primary energy within the approximate range 10(^-16) eV to 18(^-18) eV. The preliminary results from the modified spectrograph are also presented but they are shown to be statistically insufficient to be considered as evidence, for or against, the validity of the earlier data. An investigation of the dependence of the momentum spectra on primary energy and shower zenith angle, originally undertaken using data available prior to the end of the period of operation of the Original spectrograph, has been repeated in the light of the improved statistics and revised EAS data. In addition, other checks have been undertaken: (a) on the effect of the accuracy of core location on the momentum spectra, and (b) on the method of deriving the spectra from the data. The data available at the conclusion of the original experiment have also been used, in conjunction with a new theoretical study of the distortion of the muon charge ratio produced by the geomagnetic field, to estimate the height of origin of muons in EAS. It is shown that measurement of this distortion cannot be used to give sufficiently accurate assessment of the height of muon production, to allow comment to be made on the nature of the primary particle or the ultra high energy interactions. Finally, an improved analytical model of EAS is described and the results are compared with those of other workers and observation.

This thesis contains an investigation into polarisation produced by light scattered within nebulae and galaxies. In the first chapter a general outline of mechanisms, producing polarisation is given. This is followed in chapter two by a detailed analysis of the theory of scattering. Here we show the formulation of the theory for scattering from small particles (Raylei^ scattering) and scattering from larger particles, (Mie theory). Chapter three gives an overview of interstellar grains, their composition, growth, destruction, size distributions and the possible sources of their origins. This is followed in the next chapter by a study of the galaxy m82. Here is given the scientific development of the galaxy showing previous models developed and the controversy which has built up over the years on whether the galaxy actually exploded or not. Chapter five contains a dust scattering model of the galaxy. This is based upon the hypothesis that the galaxy has drifted into an enormous intergalactic dust cloud. The results and consequences of the model are presented in chapter six. The dust scattering model used for M82 assumed Rayleigh scatterers. Chapter seven shows the results from model nebulae consisting of Mie particles. Here discussion is given to the effect on the predicted results when varying the properties of the grains. We also mention the potentials of other forms of polarisation techniques.

The question of the origin of the cosmic radiation is a fundamental problem in high energy astro physics, this thesis is concerned with one particular aspect of this question namely, whether or not the cosmic ray sources are Galactic or Extragalactic. This problem is Investigated through the results of Galactic Gamma-ray astronomy. The main mechanism for gamma ray production are discussed. The observational results of Galactic Gamma ray astronomy are described. Theories about the Galactic cosmic ray sources and the distribution of these sources are described and related to the resulting distribution of cosmic rays in various propagation models. The distribution of gas in the galaxy is described. Calculations are presented which indicate that the role of Inverse Compton Scattering in producing the observed Galactic Gamma ray intensity is small. The reason for the disagreement of this result with earlier results is analysed. The distribution of cosmic rays in the inner Galaxy (0-10 kpc from the Galactic Centre) is determined from a comparison of the distribution of Gamma ray emissivity and the hydrogen distribution, this Is found to follow the distribution of sources between 6 - 10 kpc. The penetration of dense molecular clouds by cosmic rays is investigated. It is concluded that the uncertainties in the hydrogen distribution do not permit us to rule out an Extragalactic origin, from the inner Galaxy data . The distribution of gamma ray intensity in the Galactic anticentre is modelled on Galactic and Extragalactic theories and the predictions of the Galactic model are found to be in excellent agreement with observation. The cosmic ray distribution is found to be consistent with the origin in Supernovae or their remnants. It is concluded that there is rather strong evidence for the majority of cosmic ray nuclei between 1 and 10 GeV having been produced within the Galaxy.