The seeing conditions during the month of September were much above the average, 104 spectra being secured on 25 nights. While in the earlier days the average number of spectra secured per night was considerably greater, we are now observing fainter stars and in this month a special investigation of nebulae required very long exposures so the on 14 of the nights only 16 spectrograms were secured. The last four months have been the best in the observing history of the institution. While the office work did not make such good progress on account of the absence of the Director and Messrs. Harper and Young and the large amount of observing, the coming of coming cloudy weather will help in its progress.

Director J. S. Plaskett absent from Sept. 2 to Sept 28 inclusive in California attending eclipse and meeting of the American Astronomical Society. with very profitable results from discussion at the latter. Obtained 8 spectrograms on 1 night. Computed mean parallaxes and absolute magnitudes of O-type stars. Pprepared description of eclipse and meeting on route.

[ The meeting was the 30th of the American Astronomical Society and was held at the Mount Wilson Observatory, Pasadena, California on September 17 to 20, 1923. The eclipse of September 10 had attracted a large number of astronomers and many of these attended the Mount WIlson meeting., Ed.]

Research Astronomer W. E. Harper was absent all month on account of illness but returned on Oct. 1

Astronomer R. K. Young obtained 42 spectrograms for absolute magnitude and radial velocity on 4 nights. Small systematic and accidental errors in the tables for obtaining absolute magnitude were investigated and as far as possible removed. New values for absolute magnitude for the 500 stars were read off. Tables for obtaining absolute magnitude from line intensity and type were converted so as to collect the results for various types on one page instead of the results for one spectral line. Latter arrangement is the most convenient for investigating corrections to the tables for the various spectral lines while the former is much more convenient in use. Start has been made on obtaining absolute magnitudes for Boss stars. Absent on leave until Sept. 12.

Astronomer H. H. Plaskett obtained 12 spectrograms of long exposure on 10 nights, total exposure of 64 hours. Measured and reduced 4 spectrograms of Z Andromedae. Considerable successful experimental work with etalon in adjustment and test. Continued computation and discussion of the nebular spectrum and corrected the proof of Volume II, Number 12.

Observing Assistant W. H. Christie obtained 55 spectrograms on 10 nights,5 of which were all night exposures. Measured 3 spectrograms for radial velocity. Obtained the period of the binary HR 6506. Completed the card catalogue of radial velocities and made enlarged transparencies of spectrum negatives.

Clerk-Stenographer Miss H. R. Keay handled the usual correspondence, accounts and reports. Entered the plates taken during the month. Corrected the proof of Volume II, Number 12. Entered the data on absolute magnitude cards. Completed transcription of periodicals received to loose leaf books and commenced on the index for same.

Instrument Maker Foreman T. T. Hutchison assisted in observing on 21 nights and made the necessary repairs and adjustment to telescope.