50 



SCIENCE. 



[Vol. YL, No. 128. 



T = time of perihelion passage. 

 n = longitude of perihelion. 



W =77 — Q. 



Q = longitude of the ascending node. 



i = inclination of orbit. 



e = eccentricity = sin <}>. 



= eccentric angle. 



a = semi-major axis, or mean distance, 



q = perihelion distance. 



fi = mean daily motion. 



U = period of revolution. 



The equinox to which the elements are re- 

 ferred is given, since the vernal equinox is 

 continually shifting on account of the slow 

 motion of precession. 



With what has gone before, I think that 

 very little need be said in explanation of fig. 3, 

 which is drawn from a model made as I have 

 just described. The true form of a portion 

 of the comet's orbit is given, and upon it is 

 projected the earth's orbit, which, with such a 

 small value of i, appears here again as a circle. 

 The positions of the earth and comet are given 

 for several dates. 



Fig. 4 shows the entire orbit of Barnard's 

 comet (as well as that of Wolf's comet, pres- 

 ently to be mentioned), the earth's orbit, that 

 of Mars, and a small portion of the orbit of 

 Jupiter. These orbits are all represented in 

 one plane, and on so small a scale the in- 

 clinations are not great enough to cause an}^ 

 appreciable distortion. For the comets, the 

 lines of nodes and the major axes are drawn 

 in. Perihelion in all of the orbits is marked 

 P; aphelion, A. 



Fig. 5 is a map of a portion of the heavens 

 showing the apparent path of the comet among 

 the stars during the period of its visibility. 

 It was in the constellation Lupus when first 

 seen, and moved towards the north and east, 

 through the constellations Scorpius, Sagit- 

 tarius, Capricornus, and Aquarius. The place 

 of the comet is given here, also, for Jul}' 16, 

 the date of discover}^ ; Aug. 16, perihelion 

 passage ; and Dec. 1, the limit of visibilitv. 



Comet 1884 III (Wolf). —Wolf's comet, 

 an insignificant object ph^'sicall}', is moving 

 in an orbit of unusual interest. Its period is 

 about six and three-fourths years. The entire 

 orbit is shown in fig. 4, where two of the most 

 interesting peculiarities are brought out, — a 

 near approach to Jupiter in longitude 209°, 

 May, 1875 (about eight million miles) ; and a 

 near approach, at the descending node of the 

 comet, to the orbit of Mars. From both of 

 these planets the comet is evidently liable to 

 considerable perturbation, and its past and 

 future history become matters of some uncer- 

 tainty. 



Our chart shows a large part of the comet's 

 apparent path in the heavens during its visi- 

 bility. William C. Winlock. 



GEOGRAPHICAL NOTES. 



The roll of geographical journals is increased by 

 one. The Florentine section of the Italian African 

 society has been authorized by the central council 

 and treasurer to issue a bulletin, the first two fascic- 

 uli of which appeared recently. It is intended to be 

 partly eclectic, presenting geographical and especially 

 African news to its readers, and partly the oflScial 

 record of the proceedings of the section. The pres- 

 ent number contains an address by Professor Licata 

 on the role of Italy in the Red Sea, an article by A. 

 Mori on Massowah, and other matters of the same 

 sort ; bibliography, including a notice of a number of 

 papers on the zoology of Africa, which have appeared 

 from time to time in the annals of the civic museum 

 of natural history in Genoa ; African notes ; the pro- 

 ceedings of the society; and the annual address of 

 Yice-president Stefanelli on the operations of the sec- 

 tion for 1884. The new journal is free to members, 

 or may be subscribed for at the secretary's office. Via 

 San Gallo No. 33, Florence, at the rate of five lire 

 per annum. 



Dr. Seriziat has been for two years engaged in 

 collecting Lepidoptera at Collo, in the more wooded 

 district of Algeria, reaching some thirty-five hundred 

 feet above the sea. He has obtained about a hundred 

 and eighty-four species in all, — about as many as are 

 ascribed to the whole of Algeria in the most recent 

 catalogue. There are about fifty-two diurnal species, 

 — just half as many as are found at Basle in Switzer- 

 land. The cause of this deficiency is stated to be 

 the small number of succulent plants suitable for the 

 food of larvae, and the incredible multitude of insec- 

 tivorous birds. It would be a source of gratification 

 if Collo would lend to America her surplus of the 

 latter in place of our own inecffiient wild birds ; and 

 our climate would, perhaps, be quite well suited to 

 the Algerian birds, at least in certain regions. 



On the occasion of the presentation to the Rus- 

 sian representative, of the gold Vega medal recently 

 awarded by the geographical society of Stockholm to 

 Prjevalski, Mr. Elf wing, the American consul, made 

 an address on behalf of the society, which was much 

 appreciated, and which has been reproduced in the 

 ' Revue geographique ' of Renaud. Mr. de Berends 

 made a suitable response on behalf of the absent 

 explorer. This is the third award of the medal, the 

 previous recipients being Baron Nordenskiold and 

 Capt. Palander. 



The death of Madam Carlo-Serena, author of 

 geographical articles on the Caucasus, is announced 

 as having occurred in 1884 at an obscure village — 

 Oedips — in Greece, on the borders of the Aegean. 

 She was chiefly noted for her passion for mountain 

 travel, and the courage and energy with which she 



