ASTRONOMY, PROGRESS OF, IN 1890. 



passing through the increased thickness. Two 

 years will probably be required for the grinding, 

 polishing, and final testing of this huge lens. 



Dr. E. H. Williams, of Philadelphia, has gen- 

 erously given $15,000 for the purchase of a re- 

 fracting telescope of 16 inches aperture for the 

 observatory of Carletpn College, Northfield, 

 Minn. The objective is being made by J. A. 

 ,r, of Allegheny, Pa., and the equatorial 

 mounting by Warner & Swasey, of Cleveland, 

 Ohio, who two years ago constructed a steel 

 dome for that observatory. This firm has con- 

 tracts for the construction of two steel domes 

 for the new Naval Observatory, Washington, 

 D. C., one of 45 and the other of 26 feet di- 

 amet <T. The 184-inch telescope and other astro- 

 nomical instruments formerly belonging to the 

 ( 'hicairo Astronomical Society have been removed 

 to the Evanston University, and a new observa- 

 tory has been built on its grounds at a cost of 

 $75,000, a gift of James B. Hobbs, Esq. Prof. 

 (',. W. Hough is director. 



The University of Denver has received from 

 the Hon. H. B. Chamberlain, of that city, the 

 gift of an observatory, with generous equipment, 

 costing (buildings and instruments) $50,000. 

 The dome of the observatory is of iron, and is 

 built on the Hough system. The object-glass, 

 20 inches in diameter and adaptable to photogra- 

 phy, is by Alvan Clark's Sons, and its mounting 

 by Fauth & Co. Its director is Herbert A. 

 Howe, Sc. D. 



William Smith, of Geneva, N. Y., has built a 

 commodious observatory, and also a dwelling for 

 its director, in the outskirts of that village. The 

 former is furnished with a 10^-inch refractor, 

 transit circle, sidereal and mean time clocks, and 

 a Brashear spectroscope. The construction of 

 the steel dome and the mountings of the tele- 

 scope and transit circle were by Warner & 

 Swasey. William R. Brooks, the discoverer of 

 many comets, is its director. 



M;my smaller telescopes, which a few years 

 ago would have been considered large, are being 

 constructed in the manufactories of the five 

 principal telescope makers of the world, viz., the 

 Clarks, Brashear, Grubb, Calver, and Cook. 



Telescopes for Photography. Prof. Barn- 

 anl, of Lick Observatory, in a letter to the Royal 

 Agronomical Society, published in the March 

 number of the "Notices, says: "The photographic 

 telescopes now being made, except the Bruce 

 telescope, will give us but little information 

 about the structure of the Milky Way, as the 

 field of view will be too small to show the cloud 

 form-. What is wanted is a photographic chart 

 of the Milky Way made with a short-focus por- 

 trait lens of the largest attainable aperture one 

 t hat will cover at least 100 square degrees." The 

 writer has received from him two photographs 

 of the ^ivat nebula in Andromeda and two of 

 the Milky Way, the former showing 64,000 stars, 

 the latter stars innumerable, and its cloud forms 

 perfectly and beautifully delineated, the work of 

 a camera bearing a 6-inch objective. These 

 cloud forms are wonderfully true to nature, and 

 t his i- t IK- first time they have been truly revealed 

 by photography or by any other method. 



Comets. Since the last report the following- 

 named comets have been discovered: Comet/ 

 1889 was detected at W T arner Observatory, Roch- 



ester, N. Y., by Dr. Lewis Swift, on Nov. 16. 

 From its small inclination, it was immediately 

 suspected to be a periodic a fact confirmed by 

 computation from subsequent observations. The 

 subjoined elliptic elements, computed by Karl 

 Zelber, differ but little from those made by 

 others : Time of perihelion passage, Nov. 29-66411 

 Berlin mean time; longitude of perihelion, 40 

 55' 52-8"; longitude of node, 331 26' 40-1" ; in- 

 clination, 10 3' 21*1" ; perihelion distance, 1-19; 

 period, 6'91 years. 



It is probably the faintest of all the periodic 

 comets, D'Arrest's not excepted. 



Comet g 1889 was discovered by M. Borelly 

 at Marseilles, France, on Dec. 12. Though it 

 was faint at discovery, its brightness increased 

 to 23-52 on Jan. 24, 1890, or to more than twenty- 

 three and a half times its brilliancy at discovery. 

 Its motion was rapidly south, and it was soon 

 lost to view from northern observatories. The 

 following elements were computed by A. Ber- 

 berich : Time of perihelion passage, 1890, Jan. 

 26-5143 Berlin mean time ; node to perihelion, 

 200 1-52' ; longitude of node, 8 17*82' ; inclina- 

 tion, 56 43-43' ; perihelion distance, 0-26926. 



Comet a 1890 was found by Prof. W. R. 

 Brooks, Director of Smith Observatory, Geneva, 

 N. Y., on March 19. It was faint when discov- 

 ered, but in June had attained a brightness five 

 and a half times that of March 19. At this 

 writing (Oct. 1) its brightness = 0-55, and it is 

 running well with the ephemeris computed from 

 the following elements by Prof. 0. C. Wendell, 

 of Harvard College Observatory: Time, 1890, 

 June 1-15896, Greenwich mean time ; longitude 

 of perihelion, 29 2' 15-5" ; from node to peri- 

 helion, 320 18' 55-6" ; inclination, 120 30' 56-5" ; 

 perihelion distance, 1-9091. 



Comet b 1890 was discovered, on July 19, by 

 M. Coggia, of Marseilles Observatory, France. 

 Though telescopic, it must have been rather 

 bright at its perihelion passage, as it was of fair 

 brilliancy at discovery, but grew fainter so rap- 

 idly that in twenty days it had diminished one 

 half. The elements of its orbit, as computed by 

 F. Bidschof, are : Perihelion passage, 1890, July 

 8'730, Berlin mean time; from node to perihelion, 

 85 58-5' ; longitude of node, 14 25-6' ; inclina- 

 tion, 63 14-6' ; perihelion distance, 0-7661. 



Comet c 1890 owes its discovery to William 

 F. Denning, of Bristol, England, on July 23. It 

 was both faint and small, with motion almost 

 exactly south. Gradually increasing in bright- 

 ness, it reached 2-21 on Sept. 2. These are its 

 elements, according to Berberich : Time of peri- 

 helion passage, 1890, Sept. 24-6489, Berlin mean 

 time; from node to perihelion, 161 22' 24-9"; 

 longitude of node, 98 47' 39'7" ; inclination, 99 

 13' 38-7" ; perihelion distance, 1-2838. 



Comet d 1890 was discovered on Oct. 6 by 

 Barnard in right ascension 19 h 13 m 30 s , declina- 

 tion 26 7' 30". Subsequent observations proved 

 it to be D'Arrest's periodic comet, which as- 

 tronomers for several months had been search- 

 ing for. 



Denning's periodic comet of 1881, which was 

 expected to return to perihelion during the early 

 months of 1890, was not found. Search for it 

 was almost useless, as the geocentric positions 

 of both the comet and the sun were so nearly 

 alike that when near enough to have been other- 



