“…It was shown that the five sources measured, Oassiopea A and Oygnus A in England and Oygnus A, Taurus A, Virgo A, and Oentaurus A in Australia, all had angular sizes of the order of a minute to several minutes of arc, consistent with the identifications which had been made with visible nebulae. These initial measurements were extended and improved (Smith 1952b;Mills 1953;Jennison and Das Gupta 1956) and for several years represented the only results available on the small discrete sources. Subsequent measurements extended the number of known sizes to a couple of dozen, all in the range l' arc or greater (Oarter, personal communication; Edge et al 1959) and, more important, showed that a few sources appeared to have sizes less than 12" arc (Morris, Palmer, and Thompson 1957).…”