548 



NATURE 



\_April lo, 1890 



isolated as a strongly basic volatile liquid, which yields a very 

 hygroscopic hydrochloride with hydrochloric acid. On boiling 

 this hydrochloride with dilute sulphuric acid, it is decomposed, 

 with assimilation of the elements of water, into paraldehyde and 

 hydrazine — 



/n /w 



^N . NH., ^O 



The hydrate of hydrazine is readily obtained from the sulphate 

 by simple distillation with alkalies. 



The additions to the Zoological Society's Gardens during the 

 past week include an Egyptian Cat {Felis chaus) from North 

 Africa, presented by Mrs. Florence J. Waghorn ; a Stoat {Mus- 

 ■tela erminea i ), British, pre->ented by Mr. Cuthbert Johnson ; 

 two Mantchurian Cranes {Grus viridirostris) from Corea, pre- 

 sented by Mr. Campbell ; three Long-eared Owls {Asio oius), 

 British, presented by Mr. W. Geoffrey N. Powell ; a Black faced 

 Weaver- Bird {Hyphantornis sp. inc.), from South Africa, pre- 

 sented by Commander W. M. Latham, R.N., F.Z.S. ; a Three- 

 toed Sand Skink [Seps tridactylus), European, presented by Mr. 

 J. C. Warburg ; two Hybrid Deer (between Ccrviis elaphus 6 

 and Ccrvus sika ? ), deposited ; a Diana Monkey {Cercopilhecics 

 ■diana $ ) from West Africa, eight Undulated Grass Parrakeets 

 {Melopsittacus tcndulatus) from Australia, purchased ; a Rhesus 

 Monkey {Macacus rhesus), born in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



Objects for the Spectroscope. 



Sidereal -T.ma at Greenwich at 10 p.m. on April 

 iih. 1 6m. 1 8s. 



Remarks. 

 (i) The General Catalogue description of this nebula is as 

 follows : " Bright, pretty large, round, pretty suddenly much 

 brighter in the middle." In 1869, Prof. Wmlock observed the 

 spectrum at Harvard College Observatory, and stated that it 

 was continuous, with a possible bright line near A 525. The 

 nebula does not appear to have been spectroscopically examined 

 'by any other observer, so that further observations are required 

 to confirm this result. If there really be a bright line as re- 

 corded, others may certainly be expected. Comparisons with 

 ■the carbon flutings in the Bunsen or spirit-lamp flame spectrum 

 should be made. It seems highly probable that many of the 

 ■so-called "continuous" spectra of nebula; really consist of 

 bright lines or flutings superposed upon a continuous spectrum, 

 as Dr. Huggins has stated that brighter parts have been sus- 

 pected in some cases, and I myself have often noted irregulari- 

 'ties, notably in the Great Nebula of Andromeda. In 1866 Dr. 

 Huggins was careful to point out that his use of the term 

 " continuous " was not to be understood to mean more than 

 that, when the slit was made as narrow as the feeble light 

 ipermitted, the spectrum was not resolved into bright lines. 



(2) This star has a very fine spectrum of Group II. Accord- 

 ing to Duner, the bands 2-8 are wide and dark, especially those 

 in the red. This indicates, as I have pointed out on previous 

 •occasions, that the star is probably considerably advanced 



towards Group III., in which the bands will be replaced by 

 lines. It will be interesting to know if any lines exist in the 

 -spectrum of the star at present, and, if so, what lines they are. 



(3) A star of the solar type (Konkoly). The usual differential 

 observations are required. 



(4) A star of Group IV. (Gothard). Usual observations 

 •required. 



(,5) It is generally agreed that 152 Schj. is one of the finest 

 ■exaoiples of stars of Group VI. It shows the usual bands of 



carbon very strongly marked, and all of the secondary bands 

 are well visible. We have certainly still a great deal to learn 

 about stars of this group, and the present favourable position of 

 a typical example may therefore be taken advantage of for 

 further inquiry. 



(6) At the last maximum of this interesting variable, Mr. 

 Espin found that the F line was bright in its spectrum, the 

 general spectrum being a very fine one of Group II. Mr. Espin 

 also noted that the bright bands (probably the bright flutings of 

 carbon) were relatively brighter as the star was on the increase, 

 and weaker when its luminosity was decreasing. It is very im- 

 portant that a recurrence of these phenomena at the approaching 

 maximum of April 11 should not escape observation, even 

 though the star is not one which rises early in the evening at 

 this time of the year. The period of the variable is about 434 

 days, but is apparently decreasing. In 1708 it was about 500 

 days. It varies from magnitude 4-5 at maximum to about 10 at 

 minimum. A. Fowler. 



The Ai'ex or the Sun's Way.— A determination of the 

 amount and direction of solar motion is given by Mr. Lewis 

 Boss in Astronomical yournal No. 213. This determination is 

 an important one, because of the fact that, out of the 253 stel- 

 lar motions used, only 49 are known to have been previously 

 employed in a similar research, and it is by means of new mate- 

 rial and variations of arrangements in its use that any general 

 facts or laws are likely to be discovered. The stars whose 

 proper motions have been utilized were given in No. 200 of the 

 above journal, and are all contained in the Albany zone, which 

 is 4° 20' in breadth, and at a mean declination of 3° north of 

 the celestial equator. 



The method employed is substantially that proposed by Airy, 

 and in the first solution five stars haviiig proper motion greater 

 than 100" in a century were excluded, with the following 

 results : — 



825 



First series ) 

 (135 stars) j 



.Second series | 

 (144 stars) j 



Both series ( 

 combined J 



Probable errors 



6 6 21 9 



8 '6 20 '9 



7'6 21-4 



— — ± I'OO 



6/^ '-•o'-o 



.5 " c C .J 

 rf «» IS ■* - 



12-39 



1373 



1309 



o J3 



280-4 

 2857 



283-3 

 ± 69 



-f- 42-8 



+ 45-1 



+ 44*1 

 ± 3-2 



When stars are excluded whose proper motions per century 

 amounted to 40" or more, the following are the resulting 

 values : — 



Single series ) 



(253 stars) j 



Probable errors 



77 



17-80 



10-58 

 ± 0-60 



288-7 

 ± 7-2 



+ 5i"S 

 ± 3-2 



The values of the several elements of solar motion, as deter- 

 mined by Struve and Bischof, are as follows .• — 



Struve 

 Bischof 



6-0 



8-O0 

 47-58 



(using Argelander's method) 



4-36 

 33-67 



273-3 

 290-8 



2857 



+ 273 

 + 43-5 

 + 48-5 



By using the present declinations of the American ephemeris, 

 Mr. Boss finds that the value given by Struve for the declination 

 of the sun's way requires a correction of -I- 10^-4, thus making 

 ^t + 37'-7> which is more in accordance with the other values 

 given above. 



The most probable co-ordinates of solar motion might there- 

 fore be assumed to be — 



R.A. = 280°; Decl. = + 40°. 



Stability of the Rings ok Saturn. — The Bulletin Astro- 

 nofnique for February 1890 contains an interesting paper by M. 

 O. Callandreau, on the calculations of the late Clerk-Maxwell, 

 relative to the movement of a rigid ring around Saturn. It is 

 well known that Laplace found it impossible for a homogeneous 

 and uniform ring surrounding a planet to be in a state of stable 

 equilibrium, and remarked that irregularities must exist in the' 



