SMITHSONIAN REPORT. 1956. — MENZEL 



PLATE 3 



1. Typical ascending prominence. The helical structure of the luminous region suggests 

 that electric currents are partly responsible for the formation. (Sacramento Peak 

 Observatory.) 



2. Hedgerow prominence, photographed in hydrogen light with large coronagraph. 

 detailed filamentary structure. (Sacramento Peak Observatory.) 



Note 



