AZIMUTHS OF THE LICK OBSERVATORY MERIDIAN CIRCLE

Abstract

There has been a persistent tendency of our meridian instrument to give minus azimuth rates at night, during the past thirty years. The south end of the telescope generally swings to the west during the observing period. The rates have been measured by observations of the circumpolar stars, and by readings on the Mire or meridian mark, south of the instrument. The determination of rates rests entirely upon measures made during the periods of observation at night, and no dependence has been placed upon the relative changes of azimuth between successive dates, nor upon the changes of Mire readings between such dates. The changes of the azimuth of the instrument are relatively large from night to night, and they follow no known law connected with temperature or the season of the year. The difference may be as large between successive dates as it is over periods of a month or