ASTRONOMY. 443 



very rarely and only for quite extraordinary merits. You iiiid Repsold 

 are the first wlio will receive it from the present Emperor, Alexander 

 III." - - - 



"Ton will be pleased to hear that with the 30-inch refractor in good 

 nights all the most difficult double-stars discovered by Burnhum with 

 the Washington refractor can be easily measured." 



Illumination by means of the electric light. — In regard to the applica- 

 tion of electricity to illuminating the microsco])es and field of view of 

 a large fixed instrument, Dr. Gill, of the Cape Observatory, says: 

 "Electric illumination by small incandescent lamps has been applied 

 with complete success to the microscopes and field of the great theodo- 

 lite with which the azimuth observations are made. The electricity is 

 supplied to the lamps from a storage battery, which is charged dur- 

 ing daytime two or three times a week by a small Grove battery. The 

 success of the experiment has been complete. The whole arrangement 

 is so simple, clean, and convenient, and the advantages to accuracy of 

 observation by perfect uniformity of light, freedom from flicker, glare, 

 and heat can only be fully appreciated after trial." 



Method of supporting a mercury trough for reflection observations. * — 

 " The observation of the nadir has hitherto been almost impossible at 

 the Paris Observatory, owing to the disturbance of the mercury caused 

 by the traffic in the neighboring streets. Lately, however, M. Gautier 

 has devised a very simple arrangement by which this is obviated. The 

 new ajDparatus consists of two cylindrical basins placed one above the 

 other, the lower one, which contains the supply of mercury, having a 

 slightly larger diameter than the upj)er. The bottom of the lower basin 

 is pierced at its center to admit a screw which projects in a vertical di- 

 rection into the inside and is fixed in that position. A cylinder, fixed 

 as an axis to the bottom of the smaller basin, is tapped to fit the pro- 

 jecting screw, and thus, by turning this basin round its axis, it can be 

 raised or lowered in the larger vessel so as to obtain a supply of mer- 

 cury in it (by means of an opening provided for the jiurpose) sufficient 

 for observation, whilst the oscillations of the ground. Admiral Mouchez 

 states in the paper before us, are completely counteracted by the 'demi- 

 flottage' of the second basin." (Observatory.) 



Hough'' sprinting chronograph. — At the Ann Arbor meeting of the Ameri - 

 can Association, Professor Hough read a paper on the printing chrono- 

 graph that he has invented. He has given a description of the instru- 

 ment in his report as director of the Dearborn Observatory for 1885. The 

 instrument is designed to print on a fillet of pai)er, minutes, seconds, and 

 hundredths of seconds, indicated by the clock which controls it, at any 

 instant that an observing key is closed by the observer's finger. The 

 impression is made from the surface of three continuously running type 

 wheels, the swiftest of which revolves once per second. The recent im- 



*Bull. Aatron., 2 : 549; also (abstr.), Eng. Mechan., 42 : 488, 



