April 14, 1882. J 



• KNC^A^LEDGE ♦ 



513 



THE ECLIPSE OF MAY 17. 



■fTJE propose to give next week a small map showing 

 V\ ^e course of the moon's shadow during this 

 eclipse. The editor has appointed Mr. Ricliard A. Proctor 

 his special correspondent in Egypt on this occasion ; but 

 whether Mr. Proctor's numerous engagements will allow 

 him to accept the appointment is not as yet known. 



THE NEW MOON IN APRIL. 



THIS is the way in which our usually calm and reflective 

 contemporary, the Scientijic American, tells us that 

 the moon will be in conjunction with four planets on the 

 18th and 19th inst :— 



The new moon of the 1 7th commences her course with a 

 brilliant record. On the 18th, the day after her change, 

 she pays her respects to three planets — Venus, Saturn, and 

 Neptune — on the same evening. It is difficult to see the 

 moon when a d.iv old, for the crescent is but a slender 

 thread, stUl it can be done. If the evening be exceptionally 

 clear, the keen-eyed observer may behold the lovely picture, 

 the moon passing al)0ut two degrees north of \'enus and 

 three degrees and a half north of Saturn. But the love- 

 liest exhibition of the month wiU occur on the 19th, when 

 tlie two days' old crescent will be in conjunction with 

 Jupiter, and only forty minutes north of him. As the 

 moon does not set until after 9 o'clock, there wUl be 

 ample opportumty for seeing the show, if the clouds are 

 kind. 



nni 



VENDS IN APRIL, 1882. 



■^HE iScieiUiJic American has, indeed, suddenly become 

 X quite poetic over the planets. Here, for instance, is 

 its account of Venus in April, 1SS2 : — "A'enus is evening 

 star, and the only one among the planets whose movements 

 excite a marked interest during the month. She has now 

 advanced far enough in her eastern course to be seen in 

 the west soon after sunset, and to allow the observer to 

 obtain a glimpse of the beauty to be revealed during her 

 nearly ten months' course as evening star. She will soon 

 be the brightest in radiance, the largest in size, the softest 

 in colour, of the myriad golden points that glitter in the 

 celestial archway. Neither is she to be considered alone in 

 an aesthetic light. The Queen of the Stars has unwittingly 

 a mission to perform, when, closing her career as evening 

 star in December with the grand event of the transit, she 

 furnishes the Lnliabitiuits of the planet that shines so 

 brightly in her sk}-, one means for measuring the un- 

 approachable, the much-desired solution of the problem — 

 the earth's distance from the sun." 



THE NEW COMET. 



THIS comet, called " Comet Wells," is now passiug from near 

 Vega (Alpha Ljne) into Cepheus, where its course will change, 

 in May. We propose to give next week a map showing a portion 

 of its path. The following reaches us from America (Scientijic 

 .American) : — 



The elements of the orbit of the new comet are : Perihelion pas- 

 sage, June 15 ; perihelion place, 49 deg. 35 min. ; longitnde of 

 node, 20G dog. 40 min. ; inclination, 74 deg. 47 min. ; perihelion 

 distance, 10,000,000 miles ; motion direct. 



This comet appears to have no analogue in the past, as no comet 

 is known with elements sufficiently resembling these to constitute 

 reasonable belief in identity. The elements of the comet of 10'J7 

 somewhat resemble those of the present comet, but the pei-ihelion 



distance of the former is computed to be seven times as great as 

 that of the latter. 



.\t present the comet is about 100,000,000 miles from the eartli, 

 and its distance from us will probably not be less than 80,000,000 

 at any time, though further calculations will be necessary to settle 

 that point. It may be expected to make a fine display lor a few- 

 days in the early part of June. Tlie present extraordiuaiy intensity 

 of its light, which comes to us from the enormous distance of 

 100,000,000 miles, proves that it has plenty of material for future 

 display, and it will probably show a long and nearly straight tail of 

 enormous dimensions to our antipodes. How much it will give us is 

 still problematical. 



Fbofessob Maspebo is said to have succeeded in making satis- 

 factory terms with the villagers whose dwellings and mosqne 

 encumber the temple of Li:xor, his only difficulty being witli 

 Mustapha Aga, the local British Consul, whose demands are cc- 

 sidercd exorbitant. The temple is likely to yield results of the 

 highest archaeological interest. It was begun by AmenUotep III.. 

 caiTied on by Seti I., Rameses II., Horns Sabaco, and Alexander 

 CKgus; and the great pylons erected by Eameses II. are sculptured 

 with battle scenes similar to those at Aboo-Simbel, and inscribed 

 with a version of the heroic poem of Pentatu-. 



The Formation of Coal. — All attempts to explain satisfactorily 

 the formation of coal have thus far proved unsuccessful, though it 

 is generally understood that it is the product of the decomposition 

 of vegetable matter. Just how that decomposition has been bronglit 

 about chemically is a mutter which chemists have not as yet been 

 able to solve. The principal difficulty has been that it has bec:i 

 impossible to obtain a clear insight into the chemical constitution 

 of coal. It has been thought hitherto, and this is still the populiu- 

 belief, that coal is in the main pure carbon, mixed with vaiyiiig 

 quantities of bituminous substances. It has been generally 

 bcUeved that, as the product of the distillation of coal is prin- 

 cipally carbon, it would be safe to conclude that free carbon 

 actually does exist in coal. The fact that sugar, starch, Ac, 

 under similar circumstances leaves a residuum consisting of carbon 

 has never been considered a proof that that element existed in these 

 bodies in a free state. It is well-known that coals which may have 

 the same percentage of carbon, hydrogen, and oxygen, do not by 

 any means, in coking, yield the same products of distillation, and we 

 have a complete analogy for this in the behaviour of cellulose and 

 starch when subjected to distillation. Evidence points to the 

 conclusion that coal is a mixture of many and complex compounds ; 

 and the difficulty, amounting almost to an impossibility, of separa- 

 ting these compounds has much to do in rendering a chemical solution 

 of the questions involved in the formation of coal a very arduous task. 

 The production of coal by artificial means is met by great obstacles, 

 among which the absence of all knowledge concerning the con- 

 ditions under which that process actually took place is the principal 

 one. The question whether the vegetable matter to which our coal 

 veins owe their origin was amassed by drifting, or was carbonised 

 in situ, has been much debated, and there has been much discus- 

 sion on the point whether it was obtained from water or from 

 land plants. Dr. Muck, of Boehum, in a recent work to which we 

 shall refer at greater length in the future, takes up the theor\- 

 that alga; have mainly contributed to the formation of coal. It 

 is urged that the remains of marine plants are rarely found 

 in coal veins, and that shells, &c., are not often met with. 

 Dr. Muck calls attention to the fact that marine plants de- 

 compose easily and completely, losing their form entirely ; 

 and that the disappearance of the calcareous remains of mol- 

 lusks is readily explained by the formation of large quantities 

 of carbonic acid gas dtiring the process of carbonisation. In 

 accepting the marine origin of coal, it is not necessary to resort 

 to the assumption of immense pressure and high temperatures to 

 explain decomposition and the total destruction of the structure of 

 the original substance. Dr. Muck combats Fremy's bog theory at 

 length. His views are well supported by recent investigations made 

 by Herr P. F. Kcinseh, who has examined 1,200 sections of coal, 

 coming to the conclusion that that mineral substance has not been 

 formed by the alteration of accumulated land-plants. Herr Reinsch 

 claims to have discovered that coal consists of microscopical organie 

 forms of a lower order of proto|>lasm : and though he carefully ex- 

 amined the cells and other remains of plants of a higher order, he 

 computed that they have contributed only a fraction of the matter 

 of the coal-veins, however numerous they may be in some instances. 

 — Scientijic American. 



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