March. 1911. 



KNOWLEDGE. 



95 



under grant No. 100, /LOGO for: — (1) The com- 

 pletion and publication of a catalogue of about 

 10.000 stars. 8.000 being between declination —20° to 

 — 37°, to the 7'5 magnitude : these observations were 

 made between 1896 and 1901: (2) For the homo- 

 geneous determination of star positions and motions, 

 computed and discussed from all available observa- 

 tions and star catalogues, to the sixth and in some 

 cases to the 7'5 magnitude, with an accuracv of the 

 highest possible order. This Preliminarv General 

 Catalogue, formed from \arious sources, has no\\" 

 been published: it contains the positions of 6,188 

 stars reduced to the epoch 1900'0 and includes 

 results which are primarily designed to furnish 

 a large number of systematically and accurately 

 observed motions of stars. The intention was to 

 include all stars that seemed to show a proper 

 motion of 10" a century, derived from observations 

 made at various observatories. In Januar\-. 1902. 

 Professor Boss again made application to the 

 Trustees of the Carnegie Institution for aid in a 

 general investigation of both the nature and amount 

 of the motions of the stars. Specific things 

 proposed to be investigated were Ui) the direc- 

 tion and velocitv of the solar motion in space 

 to be determined with far more accuracv than at 

 present known ; (b) to investigate the subject of 

 " star-swarms," — swarms of stars moving in a 

 common direction like meteors — a new subject, to 

 which Professor Boss has been specially attracted : 

 (c) to determine with accuracv the relative distance 

 of various orders of stars ; id) to determine the 

 constant of precession more accuratelv than is now 

 known ; and to examine other questions as the\- arise. 

 Professor Boss considered that, as the basis of these 

 investigations, the motions of the stars must first be 

 accurately known, and that this would be both the 

 greater and the most laborious part of the work. 

 It is with this general investigation and the specific 

 in\-estigation {a), that Professor Boss and his staff 

 have been progressing to the extent to be indicated 

 later. 



The fact of so much having been alread\" accom- 

 plished served to prove bevond doubt to Professor 

 Boss that the real value of his results to that period, 

 about 1904, and of the final discussion, will depend 

 upon the systematic accurac\- of these determinations 

 of motion, and upon having a good determination of 

 motion for each star. Both these requirements 

 called for further special observations, the great need 

 in this direction being a new determination of the 

 positions of the standard stars, distributed from the 

 north to the south pole of the skv. Professor Boss' 

 plan proposed to the Carnegie Institution was further 

 supported by those results. The Dudley Observatory 

 Meridian Circle was then being altered to meet his 

 views with regard to such standard work. Aided by 

 a grant, the first series of re-observation of the 

 selected standard stars or points of ultimate refer- 

 ence, would be completed at Albany within about 

 two years ; after that he proposed to dismount the 

 instrument and re-erect it upon a suitable site in the 



Southern Hemisphere. The places he had selected as 

 eminently suitable were San Luiz, in .\rgentina, 

 specialh- recommended by Mr. JJavis, the chief of 

 the meteorological service, as possessing an excellent 

 and stead}' climate ; another was Bloemfontein, in 

 South Africa, highly recommended by Sir D, Gill, 

 and places in Australia were also suggested. The 

 idea in selecting a southern station was to observe 

 stars at .\lbany from the north pole to as far south 

 as possible, and then to use the southern observatory 

 for observing stars from the Albany zenith to the 

 south pole, and so interweave the two series that 

 the elimination of systematic errors of observation 

 might be effected by making them work in opposite 

 directions in the two positions of the instrument. 

 As a necessar\- addition to this proposal it was further 

 urged that special re-observations be made of those 

 stars, mostly south stars, which had been neglected 

 during the past twenty to thirty years ; the accuracv 

 of the places of these particular stars is much desired 

 in order to obtain improved knowledge of their 

 proper motions, and so help to bring up the quality 

 of their places to approximate that of the standard 

 stars. Professor Boss said that in one-fourth of the 

 southern skv, that near the southern pole, only thirt\- 

 per centum of the stars to the seventh magnitude 

 had been accurateh- observed since 1880, and scarcely 

 anv since 1894 : the need of their re-observation was, 

 therefore, ver\' great and urgent. 



In connection with the Carnegie Institution's 

 desire for the establishment of a southern observa- 

 torv it was proposed b\- Professor Boss, and warmh- 

 supported bv eminent astronomers, that his particular 

 scheme of research work, essentially referred to in 

 (ci) — the re-observation and determination of standard 

 positions of a large number of stars from the north 

 to the south poles of the skv — was specially that kind 

 of work for which a portion of the funds of that 

 Institution could be most appropriately utilized, 

 especialK' as the qualifications, time, and energies 

 of several astronomers were now awailable for 

 carrying out such a grand scheme. In making this 

 application to the Institution, Professor Boss said he 

 \\ould use the same instrument as employed at 

 Albany, which he considered to be one of the finest 

 meridian instruments in the world for such work, 

 and one in which the investigation of the division- 

 errors of its circles has been accomplished with 

 the highest degree of accuracy, by the combined 

 labours of four observers lasting more than a year. 

 He proposed to take personal charge of and responsi- 

 bility for the whole of the investigations both for the 

 northern and for the proposed southern observatory; 

 and intended to go to the Southern Hemisiihere to 

 organize the work, to remain there for a time in order 

 to ensure its smooth, speedy, and accurate running, 

 and, towards the end of the southern series of 

 observations, to re-visit that observatory to satisfy 

 himself and colleagues that no point of importance 

 liad been neglected. In making his application for a 

 grant to carry out his plans of 1902, in their most 

 complete and satisfactorv manner, he specially drew 



