4G 



KNOWLEDGE 



[February 1, 1894. 



chalk, and the pine and cedar type from the Trias on- 

 wards ; but all the wood of the older formations exhibits 

 the araucarian structure. In paljeozoic wood of the 

 araucaroxylon type each tracheide commonly exhibits 

 several rows of pits crowded together and mutually 

 compressed, so that the outer circle or border of each pit 

 presents a hexagonal rather than circular outline, giving 

 a tesselated appearance to the markings as though the 

 cell-wall were overlaid with minute mosaic. Coniferous 

 wood is much simpler than that of dicotyledons ; the 

 latter includes, beside trache'ides, cells and fibres of 

 various kinds. Palieozoic is therefore distinguished from 

 modern wood by the greater uniformity and simplicity of 

 its structure. 



The various elements entering into the composition of 

 vegetable tissues and their symmetrical arrangements 

 often give to microscopic sections, both of living and fossil 

 plants, a remarkably beautiful appearance. The trans- 

 verse section of the stalk of the common bracken, for 

 example, is a lovely object presenting an elegant lace-like 

 pattern. This feature is retained even in the fossil ; 

 silicified fern stems from Saxony have long been cut and 

 polished wholesale on account of the graceful designs 

 which the sections present. The starling's-breast mineral, 

 or staarstein of the Germans, is also a fossilized fern, 

 being formed from the stalk? of species of Parsonieffi, and 

 in the wood opals petrified vegetable tissues even attain 

 the dignity of precious stones. We have only touched the 

 fringe of a large and interesting subject, but if we have 

 succeeded in conveying the impression intended, the 

 reader will have been able to form some slight conception 

 of the singularly charming field of investigation opened up 

 by fossil botany. 



THE FACE OF THE SKY FOR FEBRUARY. 



By Herbert Sadler, F.R.A.S. 



WHENEVEE the Sun is visible, its disc should 

 be watched for spots and facuhi;. On moon- 

 less nights the zodiacal light should be looked 

 for in the south-west shortly after sunset. 

 Conveniently observable minima of Algol 

 occur at 9h. 10m. p.ji. on the 2nd ; 6h. Om. p.m. on the 

 5th ; lOh. 53m. p.m. on the 22ud : and 7h. 42m. p.m. on 

 the 25th. 



Mercury is an evening star, and is well situated for 

 observation during the last two thirds of the month — in 

 fact, this will be the most favourable evening apparition in 

 the whole year. On the 11th he sets at 5h. 58m. p.m., or 

 51m. after sunset, with a southern declination of 11° 43', 

 and an apparent diameter of 5^", tW-^^ o^ ^^^ "^isc being 

 illuminated. On the 16th he sets at 6h. 32m. p.m., or 

 Ih. 18m. after the Sun, with a southern declination of 

 7° 42', and an apparent diameter of 5^", tbV^'^s of the 

 disc being illuminated. On the 20th he sets at Oh. 58m. 

 P.M., or Ih. 34m. after the Sun, with a southern declination 

 of 4° 25', and an apparent diameter of Gj", VuVths of the 

 disc being illuminated. About this time he is at his 

 greatest brilliancy. On the 2f)th he sets at 7h. 20m. p.m., 

 or Ih. 48m. after the Sun, with a southern declination of 

 0° 6', and an apparent diameter of 7j", rather less than 

 -I'jths of the disc being illuminated. He is now at his 

 greatest eastern elongation (18° 5'). While visible. 

 Mercury passes through part of Aquarius into Pisces. On 

 the evening of the 15th he will be closely .«.,/'. A Aquarii, 

 4th magnitude, planet and star being visible in the same 

 field of view with a low power eye-piece ; and on the 18th 

 he will be near the 4th magnitude star <^ Aquarii. 



Venus is not very well situated for observation during 

 February. On the 1st she sets at 7h. 13m. p.m., or 2h. 23m. 

 after the Snn, with a southern declination of 4'^ 4', and 

 an apparent diameter of 55", yJo^hs of the disc being 

 illuminated, her brightness being little more than half 

 what it was on January 11th. On the 10th she sets at 

 Oh. 24m. p.m., with a southern declination of 3^ 43', and 

 an apparent diameter of GO", -j-g^ths of the disc being 

 illuminated, and her brightness being only about one-fifth 

 of what it was on January 11th. After this she comes too 

 near the Sun to be visible. She is in inferior conjunction 

 with the Sun on the 16th, and after this becomes a morning 

 star, but still too near the Sun to be conveniently observed. 

 During the first ten days of February Venus describes a 

 short retrograde path in Aquarius, without approaching 

 any very bright star. 



Mars and Uranus are both, for the purposes of the 

 amateur, invisible. 



The minor planet Pallas comes into opposition with the 

 Sun on the 15th, her distance from the earth being about 

 115 million miles. On the 1st her R.A. is 9h. 28fm., 

 southern declination 20^ 20'. On the 15th her Pi. A. is 

 Oh. 18im., southern declination 15° 39'. On the 28th 

 her R.A. is Oh. llm., southern declination 10'^ 11'. She 

 will appear as a OJ- magnitude star during February, and 

 may thus be possibly visible to the naked eye in the 

 absence of moonlight. During the month she describes a 

 retrograde path in Hydra, without approaching any naked 

 eye star. 



Jupiter is the brightest object in the evening sky, but 

 his diameter is perceptibly decreasing. He sets on the 1st 

 at 2h. 12m. a.m., with a northern declination of 17° 28', 

 and an apparent equatorial diameter of 40'8". He sets 

 on the lltli at Hi. 36m. a.m., with a northern declination 

 of 17^ 42', and an apparent equatorial diameter of 39-4". 

 On the 28th he sets at 8h. 40m. a.m., with a northern 

 declination of 18'^ 14', and an apparent equatorial diameter 

 of 37-4". He pursues a short direct path in Taurus 

 during the month, but does not approach any naked eye 

 star. The following phenomena of the satellites occur 

 while the planet is more than 8° above and the Sun 8° 

 below the horizon : — On the 1st an eclipse reappearance 

 of the first satellite at 8h. 2m. 8s. p.m. On the 2nd a 

 transit egress of the second satellite at 6h. 34m. p.m. ; a 

 transit ingress of its shadow at Oh. 48m. p.m., and a 

 transit egress of the shadow at 9h. 10m. p.m. On the 4th an 

 occultation reappearance of the third satellite at 5h. 53m. 

 P.M. ; its eclipse disappearance at Oh. 23m. Os. p.m., and 

 its eclipse reappearance at lib. Om. p.m. On the (ith an 

 occultation disappearance of the first satellite at lib. 59m. 

 P.M. On the 7th a transit ingress of the first satellite at 

 9h. 9m. P.M. ; of its shadow at lOh. 20m. p.m. ; a transit 

 egress of the first satellite at llh. 22m. p.ji. ; an occul- 

 tation disappearance of the second satellite at llh. 40m. 

 p.m. On the 8th a transit egress of the shadow of the 

 first satellite at Oh. 42m. a.m. ; its occultation disappear- 

 ance at Oh. 27m. p.m., and its eclipse reappearance at 

 9h. 58m. 2s. p.m. On the 9th a transit ingress of the 

 second satellite at Oh. 47m. p.m. ; a transit egress of the 

 shadow of the first satellite at 7h. llm. p.m. ; a transit 

 egress of the second satellite at 7h. llm. p.m. ; a transit 

 ingress of its shadow at 9h. 26m. p.m., and its transit 

 egress at llh. 48m. p.m. On the 11th an eclipse reappear- 

 ance of the second satellite at Oh. 5m. 9s. p.m. ; an 

 occultation disappearance of the third satellite at 7h. 51m. 

 P.M., and its occultation reappearance at Oh. 54m. p.m. 

 On the 14th a transit ingress of the first satellite at 

 llh. 4m. P.M. On the 15th an occultation disappearance 

 of the first satellite at 8h. 23m. p.m., and its ecHpse 



