April 24, 1890] 



NATURE 



595 



again dissolve on cooling. This behaviour is very character 

 istic of the acid, the barium salt showing the phenomenon 

 also in a striking manner. It is due to the different amounts of 

 water of crystallization in the salts separating at different tem- 

 peratures. The chloride of the acid radical, the amide, and the 

 anilide of the acid have also been prepared, and found to resemble 

 the corresponding derivatives of the fatty acids. 



The additions to the Zoological Society's Gardens during the 

 past week include two Indranee Owls {Syniiiim iiidraiwc) from 

 Ceylon, presented by Mr. A. R. Lewis ; two Lataste's Frogs 

 {Rana latasti) from Italy, presented by Mr. G. A. Boulenger, 

 F.Z.S. ; a Common Moorhen {Gallinula chloropus), British, 

 two Moorish Toads {Bufo jnauritanica) from North Africa, 

 presented by Mr. Cuthbert Johnson ; an Indian White Crane 

 (Gnts leitcogeranos), two Black-gorgeted Jay Thrushes {Garrulax 

 pectoralis), an Indian Muntjac {Cervultis nnintjac <J ) from 

 India, deposited; a Pacific Fruit Pigeon {Carpophaga pacifica) 

 from the Solomon Islands, four Madagascar Weaver Birds 

 {Foudia madagascaj-iensis, 2629) from Madagascar, six 

 Common Cormorants {Phalacrocorax carbo), European, two 

 Adelaide Parrakeets {Platycercus adelaidic) from South Australia, 

 purchased ; a Puma {Fclis concolor), born in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



Objects for the Spectroscope. 



Sidereal Time at Greenwich at 10 p.m. on April 24 = 

 I2h. iim. 30s. 



Remarks. 



(i, 2, 3) Although the constellation Virgo is so exceptionally 

 rich in nebulas, comparatively few of thehi have been submitted 

 to spectroscopic examination. Smyth remarks that "the situa- 

 tion of the extraordinary conglomerate of nebulae and com- 

 pressed spherical clusters which crowd the Virgin's left wing 

 and shoulder is pretty well pointed out to the practised naked 

 eye by e, 5, 7, r;, and j8 Virginis, forming a semicircle to the 

 east, whilst, due north of the last-mentioned star, $ Leonis 

 marks the north-west boundary." As it is not possible to give 

 anything like a complete list, three of the brighter ones which 

 have not yet been spectroscopically observed have been selected. 

 No. I is the remarkable spiral nebula of 99 M Virginis, and is 

 thus described in the General Catalogue: — "A very remark- 

 able object ; bright ; large ; round ; gradually brighter in the 

 middle; three-branched spiral." No. 2 is 87 M Virginis, and 

 is described as " Very bright ; very large ; round ; much 

 brighter in the middle." No. 3 is described as " Very bright ; 

 considerably large ; pretty much elongated in a direction about 

 63° ; very suddenly much brighter in the middle to a nucleus." 

 It is a remarkable fact that all the nebulae in Virgo, which have 

 so far been examined, exhibit so-called " continuous " spectra. 

 D'Arrest observed the nebulae G.C. 2930 (84 M Virginis), 2961 

 (86 M), 3021 (49 M), and Lieutenant Herschel observed G.C. 

 3021, 3132, 3227, 3229, and 3397. Some of these may be 

 re-examined for bright maxima in the continuous spectra. 



(4) The spectrum of this (Group II.) star is thus described by 

 Duner : — "The bands 2-8 are well marked by strong lines 

 which terminate them on the violet sides. But, with the excep- 

 tion of 2 and 3, they are rather narrow, and the spectrum ap- 

 proaches to the type of Aldebaran." The star is obviously at a 

 transition stage between Groups II. and III., and a special 

 detailed study of the lines and bands should be made. 



(5, 6) The spectra of these two stars have been observed by 

 Vogel, who states that the first has a spectrum of the solar 

 type, whilst the second is one of Group IV. The usual further 

 observations are required in each case. 



(7) Notwithstanding the small magnitude of this star, it has, 

 according to Vogel, a magnificent spectrum of Group VI. The 

 star is not included in Duner's Catalogue, and Vogel gives no 

 particulars as to the number and character of the bands present. 

 Further detailed observations are obviously required. The 

 intensity of the carbon band near X564, as compared with the 

 other bands, should be particularly noted. 



(8) This variable will reach a maximum about April 27. Its 

 period is about 225 days, and it varies from 7"2-8'2 at maximum' 

 to io"2-i2'8 at minimum. According to Duner, the spectrum 

 is one of Group II., but very fully developed. As no details of 

 the spectrum are given, it seems probable that the observation 

 was made near minimum, and the present maximum may afford 

 an opportunity of securing further observations. As in similar 

 variables, bright lines may also be looked for. 



A. Fowler. 



Mathe.matical Study of the Solar Corona. — The 

 Smithsonian Institution, Washington, has published a paper by 

 Prof. Frank H. Bigelow in which the solar corona is discussed 

 by spherical harmonics. The subject is treated by this theory 

 on the supposition that the phenomenon seen is similar to that 

 of free eleectricity, the rays being lines of force and the coronal 

 matter being discharged from the body of the sun, or arranged 

 and controlled by these forces. In order to give the solution 

 a general foundation the important parts of the theory of har- 

 monics specially relating to the case are recapitulated, and the 

 corresponding geometrical solution given in a notation adapted 

 to the sun. An analysis of the lines of force demonstrates the 

 applicability of the formulae of statical electricity to the coronal 

 structure, hence some repulsive force must exist on the surface 

 of the sun which acts upon the corona according to the laws of 

 electric potential. It is shown how the concentration of potential 

 at each pole throws vertical lines of force at the polar region, 

 which gradually bend each side, and finally close on the equator at 

 a certain distance from the centre. Similarly other lines are traced 

 which leave the sphere at various angles to the vertical axis and 

 have diminished potentials ; these therefore close on the equator 

 at a less distance from the centre than the high potential vertical 

 lines thrown out at the polar region. «•.-*—< 



Applying these electrical principles to the solar corona, the 

 author thinks that the straight polar rays of high tetision carry 

 the lightest substances, such as hydrogen, meteoritic matter, 

 debris of comets and other coronal material away from the sun, 

 and they soon become invisible by dispersion. The strong quadri- 

 lateral rays which form the appendages conspicuously seen at 

 periods of great solar activity are produced by four lines of 

 force having potential 0*9, 08, 07, and 06, of the potential at 

 each pole, and the explanation of the long equatorial wings, with 

 absence of well-marked quadrilaterals, seen at periods of mini- 

 mum, is that they are due to the closing of the lines of force 

 about the equator. The theory is tested by applying it to two 

 photographs taken by Messrs. Barnard and Pickering on January I, 

 1889, and Prof Langley submits it to astronomers and physicists 

 as a possible clue to the explanation of the corona and as sug- 

 gesting the direction to be taken in future o^servations and 

 investigations. 



Solar Observations. — The following is the ;V.f«W of solar 

 observations made at Rome, by Prof. Tacchini, during the first 

 three months of this year : — 



Spots and Facultc. 



