Volume 48 number 1 (2020)
(Abstract only) LS Persei is an Algol-type eclipsing binary star, with a 2.9-day period and a documented instance of a period decrease. I have extended the record of times of minima backwards by more than 50 years using the photographic plate collection at Harvard College Observatory, and up to the present using CCD observations. The extended O–C curve shows an overall concave-downward trend, corresponding to a continuous period decrease (P· = –2.3 × 10–8), and an additional nearly sinusoidal variation. The former may be caused by mass transfer from the more massive to the less massive star of the pair. A cause for the nearly sinusoidal variation is less clear.