88 UNIVEKSITY OF VIRGINIA PUBLICATIONS 



The pitch of the micrometer screw was determined at different tempera- 

 tures by transits of polar and equatorial stars and by measures of differences 

 in right ascension of stars in the Pleiades. The observed and adopted values 

 of the pitch are given in the following table: 



The value of the pitch of the screw for the mean temperature for each 

 set of observations is given by the formula — 



P = 9."856 — 0."00025(50° — t). 



The values derived from this formula were used for the fundamental 

 stars. For the other stars the mean value 9. "856 was used, the errors 

 arising therefrom being negligible in comparison with the errors of obser- 

 vation. 



On the best nights it was my custom to observe the fainter stars and 

 to look for others not catalogued by Professor Bond. Through this search 

 I found five stars, the existence of which is certain. I do not believe that 

 these stars have been catalogued before, and make a special note of their 

 positions in the hope that some one may be interested enough to look them 

 up. 



No. 2 is certainly variable. It was not seen at all during the first 

 year of observation, but on November 10, 11, and 12, 1909, it was nearly 

 as bright as 589, from which it is distant about 6". Upon February 1, 1910, 

 it was considenably fainter. No. 4 must also be variable, since during the 

 fall of 1909 it was almost as bright as 612 and 618 and considerably 

 brighter than several of the Bond stars in the region. Upon February 1, 

 1910, it also seemed to be much fainter. If either No. 2 or No. 4 had 

 attained a maximum during the period covered by Professor Bond's obser- 

 vations, it is hardly probable that they would have been overlooked by him. 

 The other three stars are very faint and would hardly have been seen by 

 Professor Bond. 



