Pauline Barmby's "Notes for discussion of Heiles' 1979 paper," presented in Astronomy 208, October 10, 1996: -survey has pretty lousy resolution (36') -seems strange that they are transforming digital data to nonlinear pictures (optical astronomers) were starting to do the exact opposite about the same time) -a lot of selection effects in this survey -expanding shell: changes size with velocity -what's going on with the negative and positive velocity shell stuff (p. 536)? -estimating distances is tricky. -difficulty getting energies -difficulty correlating these things with other objects conclusion: they see these things but can't measure them very well and don't know what they are. Better resolution would help to tell if they are real. context: as of 1984 (APJS paper) - still no unique explanation 1989 paper: magnetic pressure important in shells (67x thermal pressure) - type III supernovae: a Zwicky idea no one else bought into - 1996: paper by Rand et al.: modelling supershell in N4631 as results of impact of high velocity cloud with galactic disk - 1995: paper by Maciejewski et al: one of Heiles' supershells as multiple SNR