On the spectral gradient around wave-number 2.34.

Summary. A comparison is made between the new data on spectral gradients in "the blue spectral region" given by Chalonge and Divan (1973) and the calibration given by Ardeberg (1969). For stars of low luminosity excellent agreement is found. Only for spectral types earlier than B 3 a discrepancy is present. If the data of Chalonge and Divan are corrected for the influence of wavelength-dependent interstellar absorp lion the differences disappear completely. Also the results for supergiant stars given by Chalonge and Divan are in very good agreement with the calibration by Ardeberg. Key words: spectral gradients - supergiant stars - interstellar absorption