122 CARNEGIE INSTITUTION 



known to have sensible motions, or to be brighter than the seventh 

 magnitude. This has been undertaken with the purpose of founding 

 upon it a comprehensive examination of problems relating to pre- 

 cession, solar motion, and generally to systematic motions of the 

 stars. In this way only is it possible to gain exact knowledge as to 

 the mechanism of the heavens. 



Reduction of Old Observations. 



In recent years there has been great activity in the work of re- 

 vising the computations relating to series of meridian observations 

 made prior to the middle of the last century. This is a most im- 

 portant department of astronomical effort. Several years ago Dr. 

 Auwers, of Berlin, completed a most painstaking and masterly re- 

 vision of the star catalogue founded on Bradley's observ^ations of 

 mean date about 1755. He also effected a new reduction of Mayer's 

 less important observations of about the same date. Stone and Gill 

 have completed the reduction and publication of the long series of 

 obser\^ations made at the Observatory of the Cape of Good Hope. 

 Frisby and Brown, of the Naval Observatory, have reduced the zone 

 obser\'ations of Gilliss at Santiago in 1S50. Weiss has revised 

 Argelander's southern zones of 1850, and Seeliger those of Lamont 

 of an earlier date. Dr. Copeland, of Edinburgh, has undertaken to 

 revise the reductions for Henderson's valuable series of meridian 

 observations made at Edinburgh around 1840. Dr. Downing, of 

 the British Nautical Almanac, has published a revision of Taylor's 

 Madras observations contained in his star catalogue for 1835. For 

 some years Dr. Hermann Davis, of the U. S. Coast and Geodetic 

 Survey, has been engaged upon a new reduction of Piazzi's observa- 

 tions made at Palermo about 1800. Recently a new reduction of 

 Groombridge's observations, 1810, has been undertaken at the Green- 

 wich Observatory. Dr. Auwers has recently published a most valu- 

 able star catalogue, compiled from the Greenwich observations of 

 Pond about 181 5, and Dr. Chandler long ago proved the very great 

 value which would attach to a new reduction of Pond's later (and 

 best) work about 1830. 



It is extremely desirable that this latter work should be taken up 

 and pushed to completion, since it would undoubtedly result in a 

 star catalogue of very high precision, fairly comparable in accuracy 

 with the very best observations of Struve and Argelander and supe- 

 rior to them in some respects. 



