Many attempts have been made to interpret the systematic proper motions of the stars as the result of a movement of the solar system in space. In recent years several elaborate and extensive investigations have been made, but the increase of the available material in amount and accuracy has not led to a corresponding increase in the accuracy of the so-called “Solar Apex.” Instead, determinations from different groups of stars have shown larger differences than can be attributed to accidental error, and in particular a determination by Kobold, using Bessel's method, has given results at variance with those obtained by Airy's method.