December, 1910. 



KNOWLEDGE. 



475 



The planet may be seen in detail in quite small telescopes ; 

 even telescopes of only 2-in. aperture are sufficient to observe 

 details on the disc as well as the Cassini division in the ring, 

 using a magnification of 100. whilst the ring may be seen with 

 a magnifying power of 50. The dark or crape ring requires 

 at least a 4-in. telescope, but it is seen to better advantage in 

 larger telescopes. The diameter of the ball is 18", whilst the 

 diameters of the outer major and minor a.\es of the ring are 

 45' and 12" respectively. The Southern surface of the ring is 

 presented to us at an angle of 16° to our line of \ision; thus 

 the ring appears well open. The Moon appears near the 

 planet on the evening of the 12th. 



Uranus is approaching conjunction with the Sun, which 

 takes place 11th January, and hence is practically unobserv- 

 able, as he sets about 6 p,m, near the middle of the month. 



Neptime rises about 5.50 p.m. near the middle of the month, 

 and is due South about 1.50 a.m. The planet is situated in 

 Gemini, about four degrees South- East of the star Geminorum, 

 but in small telescopes without setting circles it is difficult to 

 identify from the numerous small stars in the same field of 

 view. He maj-, howe\er. be detected by his motion if 

 observations are made on several successive nights. 



Meteors. — The principal shower of meteors during the 

 month is the Geminids. December 10th to 12th: the radiant is 

 near Castor, in R.A. VII.'' 12"", Dec.+33°. The meteors are 

 short and quick, and difficult to record accurately. 



Minima of .^Igol mav be observed on the 15th at 9.52 p.m., 

 and at 6,41 p.m. on the 18th. The period is 2* 20" 49" from 

 which other minima mav be calculated. 



Telescopic Objects : — 



Double St.^rs. — 1 Pegasi 21'' 17'5 

 4'5. S"6 ; separation 36"'2. 



TT Andromeda: 0" 31'5'' 



N". 19° 20'. mags. 

 X. 55'^ 11', mags, 4'0, S'O; separa- 

 17', mags. 3'7. 4'7: separa- 



6"6"', X. 29° 50', mags, 5, 6-4 : separa- 



tion 36"'3. 



a Piscium 1" 56-9'°, X. 

 tion 3"'6. 



I TriangiiU 

 tion 3"'a. 



Clusters. — (^ \"I. 53. 34.1 The Perseus clusters visible 

 to the naked eye and situated about midway between 7 Persei 

 and S Cassiopeiae. These magnificent clusters are described 

 bv Sm\-th as "affording together one of the most brilhant 

 telescopic objects in the heavens." 



(M 34.) A mass of small stars about the 8th magnitude : 

 not ver\- compact. The cluster is just perceptible to the naked 

 eye about 5° Xorth-\\'est of Algol. 



SOLAR DLSTL'RB.A.XCES DURIXG OCTOBER, 1910. 

 Bv FRANK C, DENNETT, 



The revival of Solar acti\ity, mentioned last month, was 

 continued during October, yet on the 15th only faculae were 

 \isible. The way in which disturbances are drawing near to 

 the equator is a significant indication of the approaching 

 minimum of sun-spots. It further appears that the Xorthem 

 Hemisphere is nearer the end of its cycle than the Southern. 

 The longitude of the central meridian at noon on October 

 the 1st was 67° 16'. 



Xos. 70, 72, and 73 were still on the disc at the beginning 

 of October, and are therefore shown on the present chart. 



No. 75. — A group of pores seen on the 7th. which dwindled 

 to a solitarv- pore during a part of the 10th. On the 11th it 

 had redeveloped into a line of pores 68,000 miles in length, 

 but after the 11th it declined until last seen on the 14th. 



No. 75^. — A spotlet preceding the last, onlv recorded on 

 the 11th. 



No. 76. — A group of faculae on the 7th had a pore at its 

 south-west edge. This had increased to a triangular group 

 of four pores on the 10th, 3° in length, but not seen again, 



Xo, 77. — A group of three pores forming a bent line on 

 the 17th, but on the 18th there was a triangle of four, not 

 seen after. 



Xo. 77a. — A nearly circular group of eight pores on 

 the 17th, but reduced to a single pore when last seen on 

 the 18th, 



Xo. 78. — On the 16tb, close within the eastern edge or limb, 

 a bright faculic ridge was seen with a spot in front, having a 

 very black looking umbra. On the 17th the umbra was 

 surroimded by a bright fringe, whilst a little south-east there 

 was a smaller spot. .Another spot had appeared close east on 

 the ISth, as well as some pores. -A bright uprush of hydrogen 



was also observed east of the leader at 11.15 a.m. By next 

 day the leader had a diameter of 22,000 miles, and the group, 

 which had a roughly elliptical outline, had a length of 65,000 

 miles. On the 20th the spot had reached a maximum 

 diameter of 30,000 miles, but a good part of its umbra was 

 obscured b\- a triangular hazy mass. On the 21st the spot 

 began to show traces of breaking up, yet on the 23rd it 

 appeared to be in a very active state. It seemed as if a mass 

 of the photospheric matter had broken in on the northern side 

 of the spot, and two of its umbrae were brightly fringed. 

 Next day the spot had broken up, whilst the group following 

 it had almost gone. The area was marked by a triangle of 

 larger spots and a few pores from the 25th to the 27th, when last 

 seen. As it was passing round the limb on the 28th a bright 

 metallic prominence was visible. 



No. 79. — A .group, composed of a spot and pores, 44.000 

 miles in length, near the site of Xo. 70, was seen to have come 

 on to the disc on the 17th, but the spot was not seen after the 

 19th, and all were gone by the 22nd. 



No. 79a. — On the 23rd a new group, 30,000 miles in length, 

 had developed directly to north of Xo. 79. Variations 

 in size occurred among the pores, two of which continued 

 visible until the 26th. 



Xo. 796. — A considerable group of pores seen 10° east of 

 the last on the 25th. but decreased to two verj' close pores 

 on the 26th, one of which continued until the 2Sth, when it 

 was seen in a facuUc disturbance, which enclosed the entire 

 district of the 79, a. b. and c groups. 



No. 79c. — Two pores, only seen on the 25th a little south of 

 Xo. 79a. 



Xo. 80. — A group of pores first seen, close past the central 

 meridian, on the 18th, There were two pairs on the 19th. 



