Oct. 12, 1876] 



NATURE 



533 



sidered to be of natural origin. Little or no notice of 

 their contents appears to have been taken until the ex- 

 amination of them by Prof. VVyman, in i860 and 1867. 

 They are now for the most part covered by a thick forest- 

 growth, the chief trees being oaks and palmettoes, with 

 many shrubs and vines. The age of some of the oaks 

 growing upon the mounds has been estimated by their 

 annual rings at 400 years, and one, a gigantic one, at 666 

 years. Taking this into consideration, together with the 

 changes in the channel of the river, the formation of neiv 

 land, and the extension of plants and trees over it, Piof. 

 Wyman thinks that an antiquity of a thousand years 

 would not be an unreasonable age to allow for the earliest 

 shell-mounds. 



OUR ASTRONOMICAL COLUMN 



The Variable Star 34 Cygni, Nova 1600.— This 

 star, although an object of pretty frequent meridian obser- 

 vation, has probably received less attention than most 

 others from those observers who especially occupy them- 

 selves with the variable stars, owing to the circumstance 

 of the estimates of magnitude recorded at transit having 

 been remarkably accordant for upwards of a century. 

 Indeed since the year 1750, on examining the catalogues, 

 we find in the majority of cases that the star is estimated 

 5^, the only marked exception being Bessel's observation 

 in his zone 1825, September 14, when it is called 6*7. 



If, however, we examine the earlier history of this star, 

 we see there are some grounds for suspecting that one or 

 more maxima may h.ave escaped observation, unless the 

 irregularity of variation attributed to it, in the recent 

 catalogues of such objects be very great. 



The discovery of the star is ascribed to William 

 Janson, who had marked it on a celestial globe in i6co, 

 as we learn from Kepler (" De Stella tertii honoris in 

 Cygno," appended to his well-known work, '■' De Stella 

 nova in pede Serpentarii," which appeared in 1606). 

 Kepler himself was not aware of its existence till May, 

 1602, and he enters into an explanation which is, to an 

 extent, apologetical,for his not having previously remarked 

 it. At the same time he calls it a new star, and in proof 

 of its being so, adduces, in addition to Janson, the 

 authority of Justin Byrgius and Bayer, who, by the way, 

 has attached the letter P to the star in his " Uranometria," 

 and is followed by Prof. Schonfeld. By observations in 

 August, 1602, he fixed its position in R.A. 300° 46', 

 Decl. 36° 52', which agrees closely with the modern cata- 

 logues. He calls it a third magnitude in 1602, and states 

 that it continued of the same brightness during the nine- 

 teen years over which his observations extended ; :'t was 

 not quite so bright as y Cygni, but was brighter than i3 in 

 the same constellation. 



According to Liceti it appeared again in 1621, after- 

 wards diminishing, until lost altogethtr. In 1655 ^t was 

 observed again by Dominique Cassini, and gradually 

 brightened during five years, until it attained the third 

 magnitude, and subsequently diminished. Hevelius states 

 that it reappeared in November, 1655 ; it was still very 

 small in 1666, afterwards becoming brighter, though with- 

 out reaching the third magnitude. In 1677, 1682, and in 

 17 15 it was estimated a sixth magnitude, and there is no 

 further record of its increase to the maximum of 1602. 



Pigott assigned a period of eighteen years, which but 

 imperfectly represents the observations ol the seventeenth 

 century. 



Schonfeld remarks that it is doubtful whether the star 

 had its actual brightness before the year 1600, or was in- 

 visible ; perhaps the former condition will be considered 

 the more probable, notwithstanding Kepler's account of 

 its having escaped his observation from the year 1591, 

 when he commenced the study of the heavens under 

 Maestlin, and noted but one conspicuous star in the breast 

 of the Swan, 



Probably a systematic observation of 34 Cygni may lead 

 to the record of another maximum. The star is of a deep 

 yellow colour, and its position for the beginning of 1877 

 is in R.A. 2oh. 13m. 15s., N.P.D. 52° 21'. 



Its neighbour X (Bayer) Cygni, deserves special atten- 

 tion at present, the fluctuations of brightness for some 

 years past having been quite exceptional. Its position is 

 in R.A. igh. 45m. sos., N.P.D. 57° 23' for 1877-0. 



The Intra-Mercurial Planet Question. — M. 

 Leverrier made a further communication to the Paris 

 Academy, on the 2nd inst., with reference to this subject. 

 Having collected in his previous communications, chiefly 

 from the original authorities, such observations as could 

 be supposed to bear upon it in any way, he finally selects 

 for discussion those only which, in addition to the round- 

 ness and blackness of the spots, have distinct mention of 

 sensible change of position upon the sun's disk on the 

 day of observation. There are ten cases under this head 

 in the months of January, February, March, May, and 

 June, or possibly beginning of July, and October. M. 

 Leverrier remarks it is inadmissible that a body pro- 

 jected upon the sun on February 12, tvhich is the date of 

 the observation by Steinheibel mentioned in the corre- 

 spondence between Olbers and Bessel, could repass at 

 the end of March or beginning of October, i.e., when 

 arriving in the line of nodes of the objects seen by 

 Lescarbault and Lummis. This could only happen if 

 the first body moved in an orbit very little inclined to the 

 ecliptic, but in this case the necessary frequency of the 

 transits must have led to its being more often observed. 

 For the present, therefore, he confines himself to treating 

 five observations in October and March, where motion 

 like that of a planet in transit are recorded. His data 

 stand thus : — 



Ilelioc. long., 8 '60 

 ,, 16-46 



,, 17201 



179-86 

 „ 18660 



Decuppis, 1839, Oct. 2-0 



Fritsch, 1802, Oct. lo-o 



SidebothaiD, 1849, March i2-i8 ... 



Lummi?, 1862, March 19-87 ... 



Lescarbault, 1859, March 26-22 ... 



And it is found that these five longitudes are represented 

 with all the precision permitted by the nature of the 

 observations by the formula (i/ = helioc. longitude) — 



V = i2i°-49 + io°-90i7834y — o"'-52 cos. v, 

 j being reckoned in days from 1750-0. 



The differences between calculation and observation 



+ 3-5 

 + 0-8 

 -4-6 



None of the residuals exceeding a half-day's motion, 

 M. Leverrier thinks it permissible to infer that the five 

 observations appertain to the transits of the same body. 



With the above motion the period of revolution is 

 33-0225 days, and the semi-axis major 0-201. 



The existence of an intra- Mercurial body announced by 

 theory, being, according to M. Leverrier, beyond doubt ; 

 to use his own words, " nous voilh, desormais en possession 

 de donnees permettant d^s k present de constituer une 

 premiere theorie qui conduira k retrouver la planete avec 

 facility et a la faire rentrer dans le syst^me rdgulier des 

 corps celestes." In conclusion he states that he is now 

 occupied in determining the epochs of the next following 

 transits over the sun's disk. 



NOTE ON THE SUN-SPOT OF APRIL 4, 1876 

 {Communicated by the Astronomer Royal) 



ON the publication of Herr Weber's observation of a 

 round spot seen on ihe sun on April 4, reference 

 was made to the photographs taken at the Royal Obser- 

 vatory, Greenwich, on the morning of that day, and it 

 was remarked at once that there was a small round spot 



