ASTRONOMY. 4,31 



servatorio Nacional de Mexico, Sr. A. Augiiiano, director. A prelimi- 

 Dury discussion gives 35™ 57^.25 as the difl'erence of longitude, or 6^ 36"" 

 40^41 west of Greenwich as the resulting longitude of the transit-circle 

 piers of the Mexican observatory. This differs 5^.0 from the old value 

 determined by moon-culminations. The circuit was 2,583 miles long, 

 with five repeaters, and the armature time was quite constant, averag- 

 ing 0^38. The outfit of the Mexican National Observatory includes a 

 15-inch equatorial by Grubb, and an S-iuch meridian circle and a 6-inch 

 transit, both by Troughton and Simms. The personnel consists of the 

 director (Sr. Anguiano) and five assistants, {ticience., November G, 

 1885.) 



Milan (1884).— The 8-inch refractor has been used for measurements of 

 255 double stars and for observations of comets. The measures of the 

 ellipticity of Uranus cannot yet be considered free from all objections. 

 The observations on Mars seem to confirm previous results as to the 

 duplication of canals, &c. 



The large dome for the ISinch refactor is nearly completed. 



Munich (1884). — The 10-inch equatorial is now remounted and the Rep- 

 sold micrometer has been studied. It will be principally used to de- 

 termine the parallaxes of LI. 28298, 26 Draconis, Gr. 2875, Br. 3077. 



The Munich zones contain 34,000 stars, of which 0,800 reciuire reob- 

 servation. This will be accomplished in zones 6° broad. The old Mun- 

 ich zones are recomputed and a cat.ilogue (for 1880) is in preparation. 



Natal Observatory (1884). — Fifty-nine transits of the moon's limb and 

 50 transits of the nearly central crater Murchison A have been obtained 

 with the transit circle. These observations furnish data for calculating 

 the variation in the irradiation at the edge of the moon and of the ef- 

 fect of the known irregularities on the limb. Arkley Observatory, 

 England, co-ojierates in this work. An appendix to the report con- 

 tains observations of comets Pons and Barnard. 



Nice. — The observatory and its extensive grounds occupy the sum- 

 mit of a hill known as Mont Gras, some 1,200 feet above sea level and 

 distant from the Mediterranean about 3 or 4 miles. We notice that it 

 is arranged on the plan of detached buildings, a plan that has been fol- 

 lowed in the construction of n)0st large observatories of recent date. 

 On the southern slope of the hill are the dwelling houses for the ob- 

 servers, library, computing rooms, &c., and higher up are the various 

 buildings that contain the instruments. A 15-inch equatorial, 0-inch 

 meridian circle, and 3inch transit are already in use. The great steel 

 dome, 72 feet in diameter, is finished and has been found to work sat- 

 isfactorily. The peculiarity in the con.struction of this dome — the work 

 of the celebrated engineer Eiffel, of Paris — is that the greater part 

 of its weight is taken by a circular float Avhich revolves in an annular 

 tank tilled with a solution of chloride of magnesium in water. This so- 

 lution has a density of 1-25, and is able to r^isist a temperature of 40° 



