SummaryInformation is presented concerning the distributions of the intensity and radial velocity of atomic hydrogen gas at radial velocities away from zero. The observations were made with an aerial beam of 2?2 between half-power points and a multichannel H-line receiver of channel spacing equivalent to 7 km/s and bandwidth 38 kc/s ("'" 8 km/s).The gas at the higher velocities is found in the galactic latitude range blI = ± 10° arrayed in a number of spiral arms. The simply reduced observational data are compared with the refined reductions of previous workers in the case of theIt is shown that, if use is made of the radial velocity-distance models at present accepted, the principal elements of the gaseous spiral arms are clouds of enormous size. The size of the clouds and hence the thickness of the spiral arms apparently increases markedly with distance from the galactic centre greater than solar distance (R o). The masses of these large clouds remain fairly uniform atGalactic neutral hydrogen at other than small radial velocities is, in general, confined to the Milky Way regions and is observed between galactic latitudes bII = ±10°. The low velocity gas discussed in paper II ) is concentrated to the galactic plane but appears at all latitudes because of its local nature. The distribution of atomic hydrogen in the Milky Way has been subjected to intensive study and discussion by the workers in two observatories particularly: Leiden (van de Hulst, Muller, and Oort 1954; and the Radiophysics Laboratory, Sydney .Using similar reduction and analytical techniques they have produced the picture of the spiral structure of our Galaxy accepted at present. The work on the inner parts, i.e. those at distances less than the Sun-galactic centre distance, has been mainly responsible for the establishment of the new IAU System of Galactic Coordinates .This paper aims to show how the higher velocity atomic hydrogen appears to the observer before any great amount of reduction, correction, and analysis is applied. Attention is directed to the gas in the outer parts of the Galaxy where it is shown that the spiral arms appear to consist of extremely large complexes whose dimensions increase and densities decrease with distance from the galactic centre.The results have emerged incidentally from the sky survey carried out at Murraybank, Sydney, which was directed primarily towards mapping the local SummaryInformation is presented concerning the distributions of the intensity and radial velocity of atomic hydrogen gas at radial velocities away from zero. The observations were made with an aerial beam of 2~2 between half-power points and a multichannel H-line receiver of channel spacing equivalent to 7 km/s and bandwidth 38 kc/s ("'" 8 km/s).The gas at the higher velocities is found in the galactic latitude range bII = ± 10° arrayed in a number of spiral arms. The simply reduced observational data are compared with the refined reductions of previous workers in the case of theIt is shown that, if use is made of the radial velocity-di...

The distributions of intensity and radial velocity of neutral hydrogen gas of low radial velocity are presented in the form of detailed diagrams of T max., the temperature at the peak of a hydrogen line profile, and of the radial velocity value at the Tmax ..The survey, concerning the whole sky from -90° to -1-42° in declination, was made with an aerial beam of 2°.2 to half power and a multichannel receiver of bandwidth 38 kc/s and channel separation 33·2 kc/s (= 7· 0 km/s in radial velocity).The radial velocities in the galactic plane are discussed in terms of differential galactic rotation and compared with results from optical interstellar absorption lines.General comparisons are made between the neutral hydrogen and distribu· tions of continuum radio sources, H II regions, and dark nebulae and obscuration.

The neutral hydrogen gas in the Large Magellanic Cloud has been observed with the 14′.5 beam of the Parkes 210-foot telescope and the 48-channel H-line receiver. We wish to present a progress report based on computer reductions of integrated brightness and median radial velocities for some 4200 profiles. The survey is incomplete for some of the southern regions below dec. −73°. Assisting in the observations were our colleagues, M. W. Sinclair, C. J. Ohlston, and G. H. Trent and the staff at ANRAO, Parkes.