432 SCIENTIFIC RECORD FOR 1885. 



centigrade below zero. Running- wheels are used as guides and to take 

 such a share of the superimposed weight only as may be necessary to 

 secure perfect steadiness in rotation. It is evident that by adding to 

 the water in the tank the weight on the wheels can be either entirely 

 or partially relieved, and by abstracting from it, any desired pressure 

 can be placed upon these wheels. The shutter is made in two leaves, 

 and opens right and left with a rain-tight joint in the center; the open- 

 ing is about 10 feet. For a complete description of the dome, with illus- 

 trations, we must refer to VAstronomie, 4 : 206-12; Observatory y 8 : 290; 

 and N'ature, 32 : 62, 297. 



M. Faye announces that the objective of 30 inches clear aperture has 

 been finished by the Henry brothers, and has been sent to Gautier, who 

 has charge of the construction of the great equatorial; it is hoped the 

 instrument will be mounted in April, 1886. 



O'Oyalla. — Sixteen hundred and ten observations for the spectroscopic 

 JJurchnwsterung of the southern sky have been made. Color observa- 

 tions with the Zoeliner photometer are also continued, as well as various 

 other photometric and spectroscopic series. 



Oxford University Observatory. — The director's annual report was read 

 on June 3, 1885. A subsidiary observatory, for instruction, has been 

 built. Professor Pritchard has published a memoir on the evidences 

 of mutual gravitation among the components of the Pleiades. The com- 

 pletion is announced of the phometric survey of all stars visible to the 

 naked eye from the pole to — 10°. 



Paris. — Eear- Admiral Monchez has issued his report on the work of 

 this establishment during the year 1884. The completion of the reob- 

 servation of Lalande's stars has led to a new disposition of the meridian 

 instruments, one of which, on the proi)Osal of M. Loewy, is now occupied 

 with the determination of a number of circumpolar stars on his new 

 method ; the great meridian circle and the circle of Gambey are still 

 employed for observations of the minor planets and of comparison stars 

 for planets, comets, and nebulae observed with the equatorials. The 

 great telescope of 0'"'74 is still unmounted, no suitable position being- 

 available in the present state of the grounds of the observatory. M. 

 Mouchez mentions having received communications from the authorities 

 in Algeria, referring to the possibility of obtaining from the local budget 

 the greater part of the sum that would be required to mount the instru- 

 ment at the observatory of Algiers on the summit of the Boudjareah, 

 an exceptionally favorable situation, which might be visited by the as- 

 tronomers of the Paris Observatory for special observations, but the 

 council of the latter institution have not availed themselves of the prop- 

 osition, in the hope that the equatorial may yet be erected at Paris. 

 Amongst the observations made with the instruments in the west tower 

 and the Henry equatorial are many of the satellites of Uranus and 

 Neptune, the companion of SirJuSj the Tbelts of Uranus, nebulae, and 



