Differential
B-band photometry of BV Dra and BW Dra, obtained in 1965, is presented. Times of primary and secondary minima are derived and
combined with published times for a period study. Period variations are found in both binaries and magnetic cycles are proposed
as an explanation. The cycle length is 19 years in BV Dra and 8 years in BWDra
Key words eclipsing binaries, period variations - magnetic fields - cycles—stars - individual—W UMa binaries
On leave from Dyer Observatory, Vanderbilt University, Nashville, Tennessee.