422 SCIENTIFIC RECORD FOR 1883. 



ring, the observers here fail to see on the best nights. During the 

 greatest opening of the ring, which is near at hand, it is intended to 

 make a set of micrometric measures of the dimensions of the ring. Some 

 observations for stellar parallax have been undertaken ; but as the ob- 

 server resides at some distance from the observatory, such work is very 

 laborious, and it seems better to defer it until more convenient arrange- 

 ments are made. At the present time the pressing need on this instru- 

 ment is, that the observations of satellites already made should be dis- 

 cussed for the purpose of correcting the orbits of these satellites and 

 of determining the masses of the planets. This discussion has been 

 begun, and the numerical calculations are being made by Ensigns W. 

 H. Allen and J. A. Hoogewerff. 



The transit circle. — This instrument, in charge of Prof. J. B. Eastman, 

 was employed in the same class of work as in 1881-82. The observers 

 were Professor Eastman and Assistant Astronomers A. K". Skinner, 

 Miles Bock,* and W. 0. Winlock. The whole number of observations 

 made with the transit circle from October 18, 1882, to October 18, 1883, 

 is 3,880. 



The meteorological observations have been continued, as in former 

 years, by the watchmen. 



The 9.6-inch equatorial. — This instrument has been in charge of Com- 

 mander W. T. Sampson, assisted part of the time by Lieut. W. E. 

 Sewell, and part of the time by Lieut. John Garvin. It has been used, 

 as in former years, in observations of the phenomena of Jupiter's satel- 

 lites, occultations by the moon, places of comets, and for obtaining cor- 

 rections to the ephemeris places of minor planets. 



Prime vertical instrument. — This instrument is in charge of Lieut. 0. 

 G. Bowman, assisted by Ensign H. Taylor. Observations with it were 

 recommenced November 14, 1882. Continuous observations have been 

 restricted to about forty stars, in no case exceeding 2° zenith distance 

 when on the meridian ; and these, with one exception, have been closely 

 confined to the time of the two maxima of aberration. The one excep- 

 tion referred to was in the case of alpha Lyrae, which has been regu- 

 larly observed throughout the twenty-four hours, having in view the 

 possibility of a determination of its absolute parallax. Up to this time 

 about 580 observations have been secured. In the reductions, Struve's 

 formulae have been used, and the labor has been greatly lessened by 

 the use of his auxiliary tables for the prime vertical transit. 



JHeridian transit instrument. — This instrument has been in charge of 

 Lieut. U. B. Harris, and Lieut. E. 0. Pendleton has assisted. The 

 meridian transit instrument has been used for the observations of stars 

 of the American ephemeris for clock and azimuth corrections, and the de- 

 terminations of the right ascensions of the sun, moon, and major planets. 

 The total number of observations of the character mentioned is 1,408. 



* Succeeded November 1, 1883, by Prof. H. M. Paul. 



