THE SPECTROSCOPIC BINARY CAPELLA. By W. W. CAMPBELL. AN examination of six spectrum plates of a Aurigae, obtained with the Mills spectrograph in 1896-7, leaves no doubt that this star is a spectroscopic binary. The spectrum is composite. The component whose spectrum is of the solar type furnished the following velocities with reference to the solar system : On the first photograph the spectrum is of essentially normal solar type; on the others it is unmistakably different. There appears to be a second component whose spectrum contains the Hy line and the rather prominent iron lines. On the plates of September 16, October 3, and October 5, these lines are shifted toward the violet with reference to the solar type spectrum; and in the spectra of November 12 and February 24 they are shifted toward the red. LICK OBSERVATORY, THE VARIABLE VELOCITIES IN THE LINE OF SIGHT OF LIBRAE, h DRACONIS, λ ANDROMEDAE, € € URSAE MINORIS AND DRACONIS. By W. W. CAMPBELL. € LIBRAE (a 15h 18.8m, 8=-9° 57′). THE variable velocity of this star, detected several months ago, is indicated by the following results: The period is undetermined, but it seems to exceed three months. h_DRACONIS (a=16h 55.4m, 8=+65° 17′). The velocities obtained for this star are: A ANDROMEDAE (a=23h 32.6m, 8=+45° 56′). The reality of the variations indicated by the first three plates, noticed in June, is amply confirmed by five later plates. The velocities obtained up to date are as follows: An underexposed plate, not suitable for accurate measurement. The observations are apparently satisfied by a period of about 19.2 days. € URSAE MINORIS (a=16h 56m, 8=+82° 12′), The velocities observed for this star are as below: 1897 May 5 + 3km 27 -35 July 21 -10 Aug. 4 + 9 1899 July 31 -40 The period remains undetermined. @ DRACONIS (a17h 37.5m, 8=+68° 48′). The velocity of this star in the line of sight varies rapidly. Four spectrograms give the following results: Compared with the whole number of stars for which plates. have been secured with the Mills spectrograph, the nine or ten spectroscopic binaries recently discovered here seem to indicate that these systems are at least as plentiful as visual binaries. The observations for determining the orbits of these bodies are well up to date, and for several of them are practically completed. Acknowledgments are due to Mr. Wright for his skillful assistance in the observations. THE VARIABLE VELOCITY OF a URSAE MINORIS IN THE LINE OF SIGHT. By W. W. CAMPBELL. POLARIS furnishes an interesting case of variable velocity in the line of sight. Six spectrograms were obtained in 1896, as follows: 2 The agreement of these results was satisfactory, and gave no evidence of variable velocity. 1 Read at the Third Conference of Astronomers and Astrophysicists, Sept. 8, 1899. 2 Published in this JOURNAL, October 1898, p. 149. In order to test the current results of our work with the Mills spectrograph, another photograph of the spectrum of Polaris was obtained on Aug. 8, 1899. This yielded a velocity of 13.1 km, and led to the suspicion that we were dealing with a variable. Two additional plates were secured on August 9 and 14, which yielded velocities of -11.4 and -9.0 km, respectively. Inasmuch as a range of 4 km is not permissible in the case of such an excellent spectrum, the star was suspected to be a short period variable, and further observations were obtained, as on page 180. On plotting these observations, Fig. 1, it became evident that Polaris is a spectroscopic binary, having a period a little less than four days. The 1899 observations have been collected and plotted, in Fig. 2, on the assumption that the period is |