MERIDIAN ASTR0ME;TRY — BOSS. 20/ 



ment and combination of the corresponding observations will afford accu- 

 rate means for determining the amount of refraction at each station, while 

 the customary observations of circumpolar stars at lower culmination will 

 also afford values independent of these. 



Thus a twofold advantage is anticipated from this project of observation: 

 (i) Greater simplicity and probably greater accuracy in the fundamental 

 determination of position for stars for both hemispheres. (2) The accumu- 

 lation of observations on the southern sky to reduce the disparity between 

 the two hemispheres in observed material now existing. This existing dis- 

 parity is due to two sources. In the first place, useful observations of pre- 

 cision upon stars in general were undertaken later in the southern than in 

 the northern hemisphere and are relatively far less numerous. In the second 

 place, there are only three or four observatories in the southern hemisphere 

 engaged in effective work of this kind, while there are at least twenty such 

 observatories in the northern hemisphere. It should occasion no surprise 

 that the share of observing due to the southern hemisphere is entitled to 

 added support of an increased number of instruments and observers. 



Preparations for the projected expedition are already undertaken. While 

 the site of the southern station has not been definitively settled, much study 

 lias been devoted to that subject in years past. Finally, during his visit to 

 this country last summer opportunity for personal conference with Mr. 

 Walter G. Davis, chief of the meteorological service of Argentina, served 

 materially to clear up the situation. It now seems probable that in the 

 balance of advantages, among which must be reckoned the prevalence of 

 clear skies, Argentina offers desirable locations for the establishment of our 

 southern station. 



Some minor equipment in instruments and accessories will be necessary, 

 in addition to the meridian circle, and these are receiving due attention. 

 Plans for the simple constructions required are also in preparation. 



It is proposed to employ a staff of about seven persons at the southern 

 station, of whom three, at least, should be observers of experience. Under 

 this arrangement, and with the large number of clear nights attributed to 

 some of the stations under consideration, 15,000 observations per annum 

 should be regarded as a safe minimum estimate of the number of observa- 

 tions that it will be possible to obtain. 



In the interests of the entire work both north and south an observing list 

 of stars is in preparation which is likely to number about 25,000 objects. 

 Of these at least 8,000 to 9,000 will belong to that part of the sky to be 

 covered by operations at the southern station. 



Meanwhile the observations and computations requisite to the preparation 

 of the Preliminary General Catalog, as described in previous reports, is in 

 progress. As heretofore explained, this catalog will contain the computed 

 positions for 1900 and the motions for something over 6,000 stars, including 



