SummaryA low resolution (2?2) survey of the neutral hydrogen in the Magellanic Clouds has produced two important additions to our knowledge of the system. (1) A bridge of gas between the Small and Large Cloud has been mapped. (2) The Small Cloud profiles show double peaks over a wide area, suggesting the possibility of two substantially separate masses of gas.The observations are discussed in terms of the distribution of integrated brightness and the median velocity of the H·line profiles. Contours of integrated brightness are compared with distributions ofHII regions and globular clusters. The overall mass of neutral hydrogen in the system is estimated at 109MO.The contours of median velocity reveal a rotation curve for the Large Cloud from which a total mass of 7 to 10 X 109MO is estimated for this galaxy.

SummaryA survey has been made of the 21 cm line from neutral interstellar hydrogen in the Magellanic Clouds. These are the fu;st observations of this radiation from an extragalactic source.The observations show that neutral hydrogen extends well beyond the easily visible regions of each Cloud, the gas being in each case less concentrated towards the nucleus than are the bright stars. From the total radiation received, the masses of neutral hydrogen are calculated to be 6 X 10 8 and 4 X 10 8 solar masses for the Large and Small Cloud respectively. Since the Small Cloud is believed to contain much less dust, this means that the ratio of gas to dust is very different in the two systems.The measurement of Doppler frequency shifts has yielded extensive new information about radial velocities within the Clouds. The velocity distribution indicates that both Clouds are rotating. Detailed discussion of the velocities has been deferred for subsequent pUblication.

SummaryObservations of radiation from neutral hydrogen in the Small Cloud of Magellan at a wavelength of 21 em have been made using the 210 ft Parkes telescope and a multichannel receiver. Profiles were observed over an area of 30 sq deg of sky.There is good correlation between the distribution of the neutral gas and the bright stars, but no detailed correspondence with clusters or Cepheids has been found.Well· defined structure is evident in the velocity distribution of the gas, which is interpreted as originating in a number of expanding gas shells between 1 and 2 kpc in diameter and containing from 1 to 2 X 107 M 0 of neutral hydrogen.A rotation curve has been derived and the total mass of the SMC estimated at 1· 5 X 109 M 0' while the corresponding mass of neutral hydrogen in the system is 5x108 Mo.

A preliminary survey of 1420 Mc/s. hydrogen-line emission has been made over 270� of galactic longitude extending through the galactic centre, and anticentre. The radiation source is in the form of a band of varying intensity along the galactic equator. The maximum brightness temperature is about 100 �K, in the direction of the galactic anticentre. Measurements of line-profile show considerable variation, with a minimum width of 0.12 Mc/s. Double lines are evident between galactic longitudes 170 and 240� and it is suggested that these may originate in major structural features of the Galaxy. The change in the peak brightness of the line along the galactic equator may result from line broadening due to galactic rotation. On the other hand it may reveal the existence of highly emitting regions. The latter interpretation is supported by the agreement in position of the bright areas for both the line emission and the continuous spectrum galactic emission.

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