April 26, 1877] 



NATURE 



549 



Mr. Abbay, the rock is limestone, as is proved by its being 

 largely quarried and burned. Moreover, the patena soil in 

 Ouvah is not of the ordinary worthless quality, at any rate in the 

 opinion of planters owning portions of it, as they frequently 

 assert that it is as good as the jungle soil of Dimbula, and the 

 neighbouring districts. What truth there is in this I cannot say. 



Further, though cleared forest land when abandoned usually 

 runs into " chena," I could show Mr. Abbay, if he were to 

 return to Ceylon, as I wish he would, cases in which it has nin 

 into patena. The Dimbula cricket ground is a case in point. 



Pendleton, Manchester, April 17 E. Heelis 



Cumming's Electricity 



In a passage from my " Introduction to the Theory of Elec- 

 tricity " which you quote in a review of the work in Nature, vol. 

 XV. p. 526, occurs a very unfortunate misprint of the word oj for the 

 word on, which seems to have misled your reviewer, and I there- 

 fore beg a few lines to correct it. The passage in question is the 

 statement of Prop. 8, p. 203, which ought to have been written : 

 " In computing the potential on any closed circuit we may sub- 

 stitute for it any closed circuit which is obtained by projecting 

 the given circuit by means of lines of force." 



In defence of this phrase I may perhaps be allowed to point 

 out that the definition of potential quoted by the reviewer as 

 that of Sir William Thomson is not the definition of potential 

 but of electrostatic potential at a point, which is given at 

 p. 45 of my book. The phrase potential on an electrified body 

 in a field of electrical force is, I hold, perfectly legitimate, de- 

 noting the work done against electrical forces in moving the body 

 (supposing all electrification undisturbed by the movement) to an 

 infinite distance out of the field. 



The case in point, however, refers to electro-magnetic potential 

 and the potential on the closed circuit really represents the work 

 done in carrying the circuit against magnetic forces out of the 

 magnetic field. 



ihe phrase suggested in your review — induction through the 

 circuit— I had purposely avoided as liable to be confused with 

 ordinary " magnetic induction " in a mass of magnetic iron, or 

 with the ' ' self-induction " of the circuit, or even with the in- 

 duced current produced by the movement of the circuit, while 

 the phrase potential on the circuit is at once suggestive of its 

 own meaning and clear from any ambiguity. 



Rugby, April 19 L, CuMMlNG 



Remarkable Papuan Skull 



I WISH to call your attention to a remarkable Papuan skull 

 which Prof. Mantegazza showed at the last meeting of the 

 Anthropological Society of Italy. The upper jaw contained 

 very distinctly no less than four molars and two canine teeth on 

 each side, all the molars being well developed. 



Unfortunately the lower jaw is missing, but if it corresponded 

 with the upper jaw, as we may justly presume — the whole skull 

 not showing any abnormality of structure — the total number of 

 teeth would amount to forty. There are cases recorded of 

 negro-skulls showing three, four, and five supernumerary teeth, 

 but eight is certainly an extremely rare occurrence. 



It would be interesting to know whether museums or collec- 

 tions in England contain any similar specimens. J. E. Z. 



Meteor 



About 10.50 p.m. on the night of Monday, the i6thUnst., 

 the sky being cloudless and the young moon just setting, I ob- 

 served a remarkable meteor in the northern heavens. It origi- 

 nated near to the star 7 Cephei, and travelled towards the 

 eastern horizon, its path forming an angle of about 35° with the 

 perpendicular. The head, two or three times as large and bright 

 as Venus, was bluish, and left a trail of yellowish light. I took 

 it at first for a falling rocket, whose ascent I had not noticed ; 

 but its transient existence, its sudden extinction without noise or 

 sparks, and the straightness of its path, with only a slight zig-zag, 

 but no curve, preclude that explanation I think. 



Leicester, April 17 F. T. Mott 



OUR ASTRONOMICAL COLUMN 

 The U.S. Naval Observatory, Washingtox. — Under 

 the title " Instruments and Publications of the United States 

 Naval Observatory," the superintendent has circulated a series of 



photographs of the instruments at present in use in that noble 

 astronomical institution. They are taken by the heliotype pro- 

 cess, and comprise (i) the mural circle, mounted in 1844, aper- 

 ture 4-1 inch ; the transit instrument, 5 '33 inch aperture, 

 mounted in the same year, and placed in the same room beside 

 the mural circle ; the smaller equatorial, mounted in 1 844, with 

 which so much good work has been performed, aperture 9 •62 

 inch ; the transit-circle, by Pistor and Martins, Berlin, which 

 was mounted in 1866, the aperture of the object-glass 8-52 inch, 

 and the focal length 1 2 feet i inch ; a general view of the grand 

 26-inch refractor, of 32 feet 5 '8 inch focal length, mounted in 

 1873, and one of the most powerful telescopes in the world ; 

 the clock-work, &c. , of this magnificent instrument is shown on 

 a separate plate. Brief descriptions accompany these heliotypes, 

 and in addition are drawings made with the 26-inch equatorial 

 of the nebula in Orion, the omega nebula, the annular nebula 

 in Lyra, and the planet Saturn. Some account of the founda- 

 tion of the observatory and a list of its publications from 

 1845-76 precede the brief description of the instruments of which 

 views are presented. 



New Variable Star. — A recent number of M. Leverrier's 

 Bulletin International contains a notice from MM. Henry re- 

 specting a variable star in Virgo, which they state has been under 

 observation for some time. The period is about seven months, 

 and the limits of variation 8m. to I4ra. ; at present it is near a 

 maximum. The position for 1877 "o is in R. A. I2h. 27m. 32'2s., 

 N.P.D. 93° 44' 37". 



Early Observation of Solar Spots. — In our popular 

 astronomical works the Chinese are not usually credited with 

 the observation of spots upon the sun at a distant date. Gaubil, 

 however, records from the Chinese annals that on May 7, 826 

 black spots were seen on the sun's disc, and again on April 2X, 

 832. There are, indeed, few phenomena which are not noted 

 by this observant people, or rather by their watchful astrono- 

 mers ; yet, strange to say, the zodiacal light is amongst them. 

 And it 15 singular that while Kepler's star of 1604 is duly re- 

 corded, the Chinese annals have no reference to the similar 

 object in 1572, with which, the name of Tycho Brahe is com- 

 monly associated. 



Comet 1877 III. — The comet discovered by M. Borelly at 

 Marseilles, on April 14, appears to have been detected three or 

 four nights earlier by Mr. Lewis Swift, of Rochester, New York, 

 who is already the independent discoverer of more than one of 

 these bodies. We say three or four nights earlier, for although 

 the telegram forwarded to Europe through the Smithsonian 

 Institution dates the observation on the night of April 1 1, the 

 rough place there assigned agrees more nearly with the com- 

 puted position for the previous midnight. In circular No. xxv. 

 of the Imperial Academy of Sciences at Vienna, are elements by 

 Dr. Holetschek, from the first three nights' observations, which 

 it is remarked have " a very great resemblance to those of the 

 comet of the year 1762." The following orbit ha? been calcu- 

 lated by Mr. Hind from the first complete observation at 

 Marseilles, on April 14, one at Marmheim by Prof. Schonfeld, on 

 the 1 6th, and a third at the observatory of Mr. J. Gumey 

 Barclay, at Leyton, on the 19th. For the sake of comparison 

 the elements of ^the comet of 1762, calculated by Burckhardt, 

 after a new reduction of the Paris observations, are annexed. 



Comet 1877 III. Comet 1762. 

 Perihelion Passage (G.M.T.) ... April 269501 May28'3345 



Long, of Perihelion 



,, Ascending Node 



Inclination 



Perihelion Distance 



102 45 51 104 2 o 



345 53 18 348 33 5 



77 » 56 85 38 13 



I '01089 I '00905 



The motion is direct. It will be remarked that the only material 

 difference is in the inclination of the orbits to the ecliptic. The 

 comet of 1762 was discovered in the Netherlands, by Klinken- 



