observations that it described an orbit seemingly circular, having a radius of about 1". There could be no doubt that this motion must be due to the revolution of a satellite, but the latter long evaded discovery, though carefully searched for with the new telescopes which were from time to time brought into use. At length in 1895 Schaeberle found the long-looked-for object with the 36-inch telescope of the Lick Observatory. It was nearly in the direction predicted by Auwers, and a year's observation by Schaeberle, Barnard and others showed that it was revolving in accordance with the theory.
If the conclusion of Auwers that the apparent orbit of the principal star is circular were correct, the distance of the satellite should always be the same. It would then be equally easy to see at all times. The fact that neither Burnham nor Barnard ever succeeded in seeing the
Fig. 2. Apparent Orbit of α Centauri, by Professor See.
object with the Lick telescope would then be difficult to account for. The fact is, however, that the periodic motion of Procyon is so small that a considerable eccentricity might exist without being detected by observations. The probability is, therefore, that the apparent orbit is markedly eccentric and that the satellite was nearer the primary during the years 1878-92 than it was when discovered.
One very curious feature, common to both of these systems, is that the mass of each satellite, as compared with that of its primary, is out of all proportion to its brightness. The remarkable conclusions to be drawn from this fact will he discussed in a subsequent chapter.
