On the inclination of rotation axes in visual binaries

Spectral types and projected rotational velocities are determined for a number of visual binary systems with known orbits. These data, along with data for other visual binaries taken from the literature, are used to demonstrate a tendency for the rotation axes to be aligned perpendicular to the orbital planes in such systems. This tendency appears strong in F stars while the evidence for A stars is rather weak. The question of coplanarity of orbits in triple systems is briefly discussed. Subject headings: rotation, stellar - visual double or multiple stars