REPORT OF EXECUTIVE COMMITTEE. 87 



modation. One assistant, employed since May 8, 1903, in the me- 

 ridian circle department, has been engaged in the reduction of the 

 observations of the 2,800 stars in Sir David Gill's Zodiacal List. It 

 is expected that the reductions will be completed in the summer of 

 1905. The purpose of the investigation is to supply more accurate 

 positions of the principal stars near the paths of the planets of the 

 solar system, to form a basis for improvements in their orbits. The 

 assistant has also taken part, with Astronomer Tucker, in an exten- 

 sive investigation of the division errors of the meridian circle by the 

 method of simultaneous readings on both circles by the two observers, 

 and he has made more than 9,000 circle readings for this purpose. 



Three assistants have contributed, under the direction of Director 

 Campbell, to the determination of stellar motions in the line of 

 sight with the 36-inch equatorial and the Mills spectrograph ; one 

 assistant since July 17, 1903, and two assistants since June 20, 1904. 

 The direct results of their work are as follows : The securing of 

 288 new spectrograms ; the approximate measurement and reduc- 

 tion of 65 spectrograms ; the definitive measurement and reduction 

 of 240 spectrograms ; the investigation of the micrometer screws of 

 two measuring microscopes ; the keeping up of the records of the 

 investigation ; the investigation of the temperature coefficient of the 

 one-prism spectrograph, together with the design of a temperature 

 case and thermostat ; the investigation of the loss of light by absorp- 

 tion and reflection in the 36-inch objective and the correcting lens ; 

 the investigation of the loss of light by diffraction at the slit of the 

 Mills spectrograph. An additional assistant in spectroscopy has 

 been engaged for January i, 1905. 



Herman S. Davis, Gaithersburg, Md. Grant No. 102. For a new 

 reduction of PiazzV s star observations. (First report is in Year 

 Book No. 2, p. xix.) $1,500. 



Abstract of Report. — Considerable work has been done toward de- 

 termining the errors of adjustment of the meridian circle. Secular 

 variations of precession in right ascension and declination have been 

 computed for all stars by the method given vaA. N. jg6^. A critical 

 discussion of the identity of all Flamsteed stars has been made for 

 the column of star names in the final catalogue. Compilation has 

 been made in form Z of all quantities thus far obtained (which will 

 be published in the definitive catalogue), that they may be handy 

 for reference as the work progresses. Explanatory introductions to 

 many of the ' ' forms ' ' of manuscript have been written and the 

 volumes bound. 



