Abstract
For 121 southern stars of spectral types between O5 and A3, including 35 supergiants, equivalent widths and values of υ e sin i have been measured from direct-intensity tracings of spectrograms with original dispersion 150 μ , Å –1 . The central depths of the Balmer lines of H I for slow rotators increase monotonically with reciprocal temperature θe , in close agreement with predictions on the basis of model atmospheres computed by Mihalas. For the stars from B3 to B9, the strengths of the He I triplet lines 4026, 4471 follow a single relation with the intrinsic colour-index Q . At class B I , however, the mean equivalent width for these lines ranges over a factor of 3, increasing from supergiants through stars near the main sequence to those with hydrogen in emission, and showing a positive correlation with υ e sin i .
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