332 ANNUAL EEPOET SMITHSONIAN INSTITUTION, 1910. 



Without doubt, however, the greatest problem in the cartography 

 of the southern skies which awaits the observatories of the Southern 

 Hemisphere is the completion of their respective shares in the great 

 photographic map of the heavens mentioned above, w^hich w^as in- 

 augurated at the International Conference in Paris in 1887. As is 

 well known, this plan, in its entirety, involved the construction of a 

 photographic map of the entire sky down to the fourteenth stellar 

 magnitude, for which about 22,000 plates were to be taken, and the 

 total number of the stars registered on the plates would probably 

 reach 20.000,000. Supplementary to these charts the plans con- 

 templated the publication of a great catalogue of perhaps 2,000,000 

 stars down to the eleventh magnitude, based on plates or shorter ex- 

 posure time. The task was apportioned among 18 observatories in 

 the two hemispheres. The observatories south of the Equator which 

 possess photographic equatorials of the uniform type adopted for 

 the work are those at La Plata, Cordoba, the Cape, Santiago, Perth, 

 Melbourne, and Sydney. It was proposed that the entire work be 

 repeated in 100 years. But so vast is the scope of this program that 

 even in the Northern Hemisphere this project, whose value for the 

 astronomy of position of the future can scarcely be overestimated, 

 has by no means made the progress anticipated for it at the time of 

 its inception. Owing to the cost, only a few of the cooperating ob- 

 servatories have agreed to publish the great maps, and among south- 

 ern observatories Perth has decided to take only the plates to the 

 eleventh magnitude and to publish the resulting catalogue. Perth has 

 taken all the plates in its zone, and has commenced the measures for 

 the Catalogue. The section apportioned to the Cape of Good Hope 

 is now nearly completed, both as to the taking of the plates and their 

 measurement, and rapid progress is being made at Sydney, Mel- 

 bourne, and Cordoba. Up in 1908 nothing had been done at La 

 Plata or Santiago, though Dr. Ristenpart, recently appointed director 

 of the National Observatory at Santiago, will make every effort for 

 the prompt completion of the zone assigned to him; the work of 

 taking the plates has already been begun under the direction of Dr. 

 Zurhellen. It w^ould seem that the publication of the costly maps 

 might well be abandoned, for the plan adopted at Oxford of publish- 

 ing only the coordinates of the stars would be far cheaper and fully 

 as useful. 



Excellent work has been done in determination of stellar parallax 

 at the Cape of Good Hope, but the difficult field of work which has 

 for its aim the determination of the distances of the stars by the 

 heliometer or modern photographic methods is still practically un- 

 touched in the Southern Hemisphere. Parallaxes of only 17 stars 

 south of declination —30° have been published, while north of this 



