NA TURE 



['June 2 2, 1882 



Greenwich mean times. The quantities within square brackets 

 are logarithms of seconds of time. 



The Cordoba Observation of Comet 1881 II., on June 

 11. — In Nature, vol. xxv. p. 519, we gave an account of Dr. 

 Gould's observations of the great comet of last year, on the 

 evening of June 11, when be compared it with an object which 

 he could not identify as a fixed star, and it was mentioned that 

 Mr. Tebbutt had suggested that the objects really observed were 

 not the comet and a star, but the two stars A Eridani and Bradley 

 71S, which have almost precisely the differences of right ascen- 

 sion and declination that were recorded on the night in question. 

 This explanation we considered a probable one, and the same 

 view was taken by the editor of the Astroiwmische Nachrichten, 

 which has occasioned a further communication on the subject 

 from Dr. Gould, who rejects Mr. Tebbutt's suggested solution of 

 the difficulty. 



Dr. Gould says the appearance of the comet on June 1 1 pre- 

 cluded the slightest doubt as to its identity. "The tail itself 

 could not be seen with the telescope, it is true, but the large, 

 diffuse, and very elongated head, much brighter and more 

 defiuite on the advancing side, was sufficient to enable the 

 veriest tyro to recognise it as a comet." He was placed neces- 

 sarily on the top of a high observing chair, which he did not 

 leave during the observations, the records being made by his 

 assistant. He had made several sweeps to find a suitable com- 

 parison-star, and was about to commence a new one, when he 

 saw the object referred to above, "at the upper part of the field 

 on the left, while the comet was on the right, below." The 

 four published comparisons were then made, and whilst he was 

 in the act of pointing the micrometer-thread upon the comet for 

 a fifth, it disappeared below the horizon. He adds, that no jar 

 of the instrument had taken place ; " the field of the telescope 

 was fully under control from the beginning, the declination- 

 clamp remaining tight throughout," and he insists that no one 

 who saw the comet could have entertained the idea that any 

 amount of blurring could have given such an aspect to a fixed 

 star, though it were far brighter than A Eridani. And he doubts 

 whether a star of the sixth magnitude would have been visible 

 under the circumstances. He made experiments on subsequent 

 evenings, by looking at known stars of different magnitudes 

 when close to the horizm and through different degrees of haze, 

 but in no case did he find one ofler the appearance noted on 

 June II, Hence, he proceeds: "I can only suppose another 

 comet to have been in the field. That it was not a companion- 

 comet is manifest, not only from the relative motion, and from 

 an examination made the next day, but still more from the abun- 

 dant scrutiny in the northern hemisphere, which could not have 

 failed to detect any companion. That it was not a fixed star, 

 was evident from the beginning." 



Thus the matter is left by Dr. Gould, who, it must be ad- 

 mitted, is by far the most competent judge of the probable 

 explanation of the difficulty. 



Maskelyne's Solar Parallax. — By communications from 

 Mr. J. Morris, Hatfield Hall, Durham, and Mr. B. J. Hopkins, 

 Marlborough Road, Dalston, we learn that the value of the 

 solar parallax given by Maskelyne, to which allusion was made 

 in this column last week, appears in the third edition of Vince's 

 " Elements of Astronomy," Cambridge, 1810 : it was therefore 

 published during his life-time. 



THE ROYAL SOCIETY OF CANADA 



'"THIS Society, which has been founded under the auspices of 

 the Marquis of Lome, and is intended to be to Canada 

 what the Royal Society and the Institute are to England and 

 France respectively, held its first meeting on May 25, 26, and 

 27. Inaugural addresses were delivered on the 25th by the 

 Marquis, Principal Dawson, and the Hon. P. J. O. Chauveau. 

 For the purpose of reading and discussing papers, the Society 

 is divided into four sections : — (1) French literature, history, and 

 allied subjects ; (2) English literature, history, and allied sub- 

 jects ; (3) mathematical, physical, and chemical sciences; (4) 

 geological and biological sciences. The following papers were 

 read in Section 3 : — Note on zinc sulphide, by T. Mcl'arlane. 

 On the "transition" resistance to the electric current at the 

 bounding surface between amalgamated zinc and solutions of 

 zinc sulphate, by Prof. J. G. MacGregor, D.Sc. The " tran- 

 sit n " resistance in this case was shown to be at any rate not 

 greater than a small fraction of an ohm, the current being weak 



and the electrodes large. The method of measurement employed 

 was a modification of that formerly used by Beetz. — On the 

 measurement of the resistance of electrolytes by means of 

 Wheatstone's bridge, by the same. In this paper, a new mode 

 of using the bridge was described. Alter»ate currents were sent 

 through the bridge, and brought into the same direction by a 

 commutator in the galvanometer branch, in which one of Thom- 

 son's galvanoscopes was inserted. Two of the arms contained 

 equal metallic resistances; the other two contained, besides 

 metallic resistances, electrolytic cells the same in all respects, 

 except as to length. Thus the errors due to polari-ation and 

 possible "transition" resistance were eliminated. — On molecular 

 contraction in natural sulphides, by Prof. E. J. Chapman. — On 

 the law of facility of error in the sum of n independent 

 quantities, each accurate to the nearest unit, by Chas. Carpmael, 

 M.A. The chance of the error in the sum lying between y\ and 

 y. 2 , where r 2 -)\ is small, was shown to be 



the series to be continued as long as the part raised to power 

 « - 1 is positive. This series is approximately equal to 



/^/±.^ n [y s -yj 



— A symmetrical investigation of the curvature of surfaces ; 

 including a discussion of the plane sections of quadrics, the axes 

 of conic sections and of quadrics, by Prof. A. Johnson, LL.D. 

 In this paper it was shown that the leading theorems concerning 

 principal radii of curvature, directions of principal sections, 

 umbilics, lines of curvature, &c, can be obtained directly by a 

 purely analytical investigation, elementary and symmetrical in 

 its character, of the plane sections of a quadric. — Note on the 

 deduction of the equation of continuity, by Prof. Loudon. — 

 Note on the motion of a chain on a fixed curve, by Prof. Cherri- 

 man. — Note on the application of a remarkable determinant, by 

 the same. — Note on a question of probabilities, by the same. — 

 On the general regulation of civil time, by Sandford Fleming, 

 C.E. — On the utility of geometry as applied to the arts and 

 sciences, by Chas. Baillarge. 



The following papers were read in Section 4 : — The distribu- 

 tion of some saline and other plants in the West, by Prof. 

 Maconn. This was an oral exposition, aided by a lan;e map of 

 certain peculiarities in the distribution of maritime Eastern and 

 Western plants in the interior of the continent, and of some 

 peculiar extensions of Southern plants to localities far north of 

 their usual range. — Note on a general section from the Lauren* 

 tian axis to the Rocky Mountains, north of the 49th parallel, by 

 Dr. G. M. Dawson. This paper gave a summary of the latest 

 facts respecting the succession and distribution of Cretaceous 

 and early Tertiary beds in the North- West Territories, and of 

 the facts obtained respecting their subdivision into groups, and 

 the useful deposits of coal and lignite contained in them. — 

 On the cretaceous and tertiary floras of British Columbia and 

 the North-west territory, by Dr. J. W. Dawson, F.R.S., &C. 

 The researches of the Geological Survey have resulted in the 

 collection of series of fossil plants from a number of localities in 

 the cretaceous of the Pacific coast, and of the eastern base of the 

 Rocky Mountains, in the laramie or lignitic group of the plains, 

 and in the Tertiary Lake Basins of British Columbia. From 

 these it appears that while up to the Middle Cretaceous a flora 

 of strictly Mesozoic character, consisting of pines, cycads, and 

 ferns prevails, the Middle and Upper Cretaceous show the in 

 traduction of a larger number of broad-leaved evergreens of 

 modern types. Though there seems to be a continuous pre- 

 valence of warm and temperate conditions, from the Upper 

 Cretaceous, up to the Pliocene, the groups of plants observed 

 may he classed as — (1) Lower and Middle Cretaceous ; (2) 

 Middle and Upper Cretaceous, with modern evergreens, as 

 Salix, Populus, Magnolia, Bctttla, Quereiis, &c, and fan palms 

 and cycads ; (3) Laramie or Fort Tunis group, probably a tran- 

 sition from the Cretaceous to the Eocene, with many new forms : 

 (4) Tertiary Flora of the probably Miocene Tertiary of British 

 Columbia. Descriptions and figures of these plants are being 

 prepared, and it is hoped may soon be published. — On the 

 anatomy and development of cestoid worms, by Prof. Ramsay 



