Published online by Cambridge University Press: 14 August 2015
Profiles of various lines in the spectra of umbrae are discussed, emphasizing the use of purely umbral lines. In the dark core of a large umbra the field strengths measured from various lines are the same, yielding 3080 ± 50G. In regions with umbral dots the field strengths do depend on the spectral line; the strengths are lower than in the dark core. Some conclusions are discussed.