The β Cephei stars 12 and 16 Lacertae in 1979

About 650 blue filter photoelectric observations of 12 and 16 Lacertae, secured in the summer and autumn of 1979 at the Bialkow station of the Wroclaw University Observatory, are presented. An analysis of these data is then carried out. In the case of 12 Lacertae no substantial change in the frequency spectrum is detected relative to the earlier results. As far as 16 Lacertae is concerned, it is found that the decrease of all three pulsation amplitudes, noted in 1977, has probably continued through 1979. The observations of 16 Lacertae include fragments of three successive eclipses of the star by its invisible companion. These new data confirm the ephemeris derived previously from the 1965 and 1977 observations. 8 refs., 5 figs., 8 tabs. (author)