The first attempt to determine the solar apex (as the point towards which the solar motion is directed is termed) was made in 1783 by Sir William Herschel.
There is for example some evidence that the declination of the solar apex is really increased when the motion is referred to fainter stars.
The older one - which may be called the " one-drift " hypothesis, since according to it the stars appear to form a single drift moving away from the solar apex - requires that the apparent directions of motion should be so distributed that fewest stars are moving directly towards the solar apex, and most stars along the great circle away from the solar apex, the number decreasing symmetrically, for directions inclined on either side of this great circle, according to a law which can be calculated.
The deviation is unmistakable; in general the direction from the solar apex is not the one in which most stars are moving; and, what is even more striking, the directions, in which most and fewest stars respectively move, are not by any means opposite to one another.
The position of the solar apex calculated in this way agrees satisfactorily with that found by the usual methods.
