ASTRONOMY — DAVIS, NEWCOiMB. 83 



mediate divisions can be measured directly by means of the micro- 

 scopes of one circle from the nearest 10' division. 



The measurement of the plates of Eros, secured with the Crossley 

 reflector, has not yet been begun, but the services of the necessary 

 computers have been engaged. 



Davis, Herman S., Dover, Delaware. Grant No. 232. Nerr reduc- 

 tion of PiazzV s star observations. (For previous reports see Year 

 Book No. 2, p. xix, and Year Book No. 3, p. 87. > $1,500. 



Abstract of Report. — Meridian Circle: Determination of the con- 

 stants of this instrument has been continued. Constants for 378 

 dates have been determined out of the 2,000 dates on which obser- 

 vations were made. A record of all observations from 1791 to 1 813 has 

 been compiled from the manuscripts by bringing together on separate 

 cards all the observational data concerning each star, preliminary to 

 application of the instrumental corrections and combination of the 

 numerous observ^ations into one mean for the definitive catalogue. 

 Transit Instrument : All the observations not arranged by Piazzi 

 into regular corsi, but printed in the Storia Celeste as " Osservazioni 

 Staccate, ' ' have been arranged in corsi and copied into printed forms. 

 The reductions from apparent to mean place at 1800, for all dates and 

 stars, have been computed, interpolated, verified by independent dupli- 

 cates, and inserted where finally needed in the forms. Every time 

 of transit on each of the five wires has been separately reduced to the 

 mean of the wires for all dates and all stars and checked by duplicate. 

 The voluntary cooperation of Prof. J. G. Porter and Prof. R. H. 

 Tucker in reobserving all the Piazzi stars for the epoch igoo has 

 been brought to a successful conclusion by their publication of the 

 two catalogues mentioned in the bibliography of this Year Book, 

 pages 48, 49. 



This report closes 454 weeks of work on the new reduction. Within 

 this time eighteen different persons have been engaged for varying 

 periods of time, only two having worked continuously from the 

 beginning to the present time. 



Newcomb, Simon, Washington, District of Columbia. Grant No. 

 233. Investigation of the 7nea?i vtotion of the moon from observatio?is 

 from the earliest historic times to the prese?it. (For previous reports 

 see Year Book No. 2, p. xxi, and Year Book No. 3, p. 90), $2,500. 

 Grant No. 254. To aid investigations in mathematical astro7iomy , 

 statistical methods, and economic science, $5,000. $7, 500, 



Professor Newcomb submits the following list of researches which 



he lias carried on with the aid of the above grants : 



