94 



KNOWLEDGE. 



[Apbh, 2, 1894. 



should be mentioned that Prof. Marshall Ward has not 

 confidence in his cultures, and does not seem inclined to 

 give these minute bodies a similar place in his classifica- 

 tion of organisms. 



It may be noted in conclusion that the leguminous 

 plant, being the stronger of 

 the two symbionts, directs the 

 growth. It provides space 

 in which the bacteroids may 

 develop by means of the 

 zone of merismatic cells, and 

 it encloses them in a corky 

 tissue, so that their develop- 

 ment may go on undisturbed 

 by external influences. 



At the death of the bac- 

 teroids the plant absorbs the 

 nourishing matter provided 



Fig. 12. — Section showing 

 bacteroids budding from tip 

 of livpba. 



by them, and thus is a distinct gainer in the matter of 

 assimilated nitrogen. Further, the tubercles being 

 situated near the vascular bundle, a ready source of 

 nutrient material, in the form of carbo-hydrates (elaborated 

 in the leaves), is always open to bacteroids, and at the 

 same time the products of decomposition of their bodies 

 can be conveyed to the green plant as required. 



THE FACE OF THE SKY FOR APRIL. 



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



AM.\GNIFICEXT group of sunspots has lately been 

 visible on the Sim's disc. An annular eclipse of 

 the Sun will occur on the 5th, but no portion of 

 it will be visible in these islands. Conveniently 

 observable minima of Algol occur at lib. 6m. 

 P.M. on the 6th, at 7h. 55m. p.m. on the 9th, and at 9h. 

 37m. p.Ji. on the 29th. 



Mercury is a morning star in the sense of its rising 

 before the Sun, and is at his greatest western elongation 

 (27|°) on the 10th, but as during the whole month he 

 does not rise more than forty minutes before the Sun, he 

 cannot be detected by the naked eye. 



Venus is a morning star, but is decreasing in apparent 

 diameter and brilliancy, her brightness at the end of the 

 month being about two-thirds of what it was towards the 

 end of March. She is at her greatest western elongation 

 (46^°) on the 27th. On the 1st she rises at 4h. 3m. a.m., 

 or Ih. 85m. before the Sun, with a southern declination of 

 8° 57', and an apparent diameter of 33^", -j^V'!^^ of ^^^ 

 disc being illuminated, and her brightness being about 

 equal to what it was on January 21st. On the 11th she 

 rises at 3h. 48m. a.m., or Ih. 27m. before the Sun, with a 

 southern declination of 7° 32', and an apparent diameter 

 of 29|'', Tu'^s of the disc being illuminated, and the 

 brightness of the planet bemg about equal to what it was 

 on March 11th. On the 21st she rises at 3h. 32m. a.m., 

 or Ih. 23m. before the Sim, with a southern declination 

 of 5° 16', and an apparent diameter of 251", Tooths of the 

 disc being illuminated, and her brightness being about 

 equal to what it was on March 7th. On the 30th she 

 rises at 3h. 17m. a.m., or Ih. 20m. before the Sun, with a 

 southern declination of 2° 39', and an apparent diameter 

 of 28", iVo*'^!^ of *^^ "^isc being illuminated. During the 

 month Venus pursues a direct path through part of 

 Aquarius into Pisces. On the morning of the 4th 

 she is very near the 4i magnitude star 6 Aquarii, 

 and on the following morning the 5} magnitude star p 

 Aquarii. 



Mars is, for the purposes of the amateur observer, 

 invisible. 



Jupiter is an evening star, but is so rapidly approaching 

 the Sun that we only give an ephemeris of him for the 

 first half of the month. While visible he pursues a direct 

 jmth in Taurus, through a region barren of naked eye 

 stars. On the 1st he sets at lib. Im. p.m., with a 

 northern declination of 19° 23', and an apparent equatorial 

 diameter of 34^". On the 15th he sets at lOh. 23m. p.m., 

 with a northern declination of 20° 8', and an apparent 

 equatorial diameter of 33". The following phenomena 

 of the satellites occur up to the 15th, while the planet is 

 more than 8° above and the Sun 8° below the horizon : — 

 On the 2nd an occultation disappearance of the second 

 satellite at 9h. 16m. p.m. On the 8rd a transit ingress of 

 the shadow of the first satellite at 7h. 28m. p.m., a transit 

 egress of the second satellite itself at 8h. 38m. p.m., and 

 of its shadow at 9h. 36m. p.m. On the 5th an occultation 

 disappearance of the second satellite at 9h. 24m. p.m. On 

 the 6th a transit ingress of the shadow of the third 

 satellite at 7h. 32m. p.m., and its transit egress at 9h. 87m. 

 p.m. On the 7th a transit egress of the shadow of the 

 second satellite at 8h. 58m. p.m. On the 10th a transit 

 ingress of the first satellite at 8h. 25m. p.m., and of its 

 shadow at 9h. 18m. p.m. On the 11th an eclipse re- 

 appearance of the first satellite at 8h. 49m. 57s. p.m. On 

 the 13th a transit ingress of the third satellite at 

 8h. 6m. p.m. On the 14th a transit ingress of the shadow 

 of the second satellite at 9h. 6m. p.m. 



Saturn is an evening star, rising on the 1st at 7h. 14m. 

 P.M., with a southern declination of 6° 14', and an apparent 

 equatorial diameter of 18'7" (the major axis of the ring 

 system being 43" in diameter, and the minor 9|"). On 

 the 15th he rises at 6h. 13m. p.m., with a southern declina- 

 tion of 5° 50', and an apparent equatorial diameter of 18-7" 

 (the major axis of the ring system being 43" in diameter, 

 and the minor 9i"). On the 30th he rises at 5h. 8m. p.m., 

 with a southern declination of 5° 26', and an apparent equa- 

 torial diameter of 18'6" (the major axis of the ring system 

 being 43" in diameter, and the minor 9"). On the 

 evening of the 11th the d^ magnitude star 72 Virginis 

 will be about j' south of Saturn, and at lOh. p.m. there 

 will be a conjunction of this star with Rhea. lapetus is 

 at his eastern elongation on the 9th, and in inferior con- 

 junction on the 27th. Saturn is in opposition on the 11th, 

 at a distance from the earth of about 808 millions of 

 miles. During the month Saturn pursues a retrograde 

 path in Virgo, being about 23' south of 74 Virginis, 5th 

 magnitude, on the 6th. 



Uranus is an evening star, and but for his southern 

 declination would be favourably placed for observation. 

 On the 1st he rises at 9h. 26m. p.m., with a southern 

 declination of 15° 51', and an apparent diameter of 3-8". 

 On the 30th he rises at 7h. 26m. p.m., with a southern 

 declination of 15° 30'. Dm-ing the month he pursues a 

 retrograde path in Libra, up to and beyond a-. He is in 

 conjunction with a- Librre (3-0 magnitude) at lb. p.m. on 

 the 27th, of course in bright sunlight, and at lOh. p.m. he 

 is only 3*0s. p. and 4' 20" north of it. At 8h. p.m. on the 

 28th he is in conjunction with a^ (5'3 magnitude) at 6b. 

 p.m., 2' 15" to the north, but the asterism does not rise till 

 about 7h. 30m. p.m. At lOh. p.m. that evening he will be 

 l-7s. />. and 2' 23 ' north of a'. Asa' and Uranus are nearly 

 of the same magnitude and colour, this, if the weather be 

 clear, will prove a very interesting phenomenon, especially 

 as the Moon will be absent, o' a'-^ Librse form a wide 

 double, not, however, divisible with the naked eye on 

 account of the inequality of the stars, 231 " apart in the 

 direction of 314^°. A map of the stars near the path of 



