May 19, 1892 



NATURE 



65 



ing a spot maximum the sun's atmosphere is becoming more 

 and more disturbed. At the time of greatest obscuration the 

 blood-red tinge, caused by the absorption of our atmosphere, 

 became very apparent, but this gradually wore off as the brighter 

 part of the moon made its appearance. 



From a series of photographs of the eclipsed moon taken at 

 intervals of about a quarter of an hour, the penumbra in some 

 of them was very distinct, especially in those taken near the 

 time of greatest obscuration, the exposures then being compara- 

 tively long. At mid eclipse an attempt was made to obtain a 

 photograph of the whole disk of the moon, as it appeared so 

 distinct and clear on the ground glass, but even an exposure of 

 I2s., using extra rapid dry plates and a 30-inch reflector, was not 

 sufficient to bring it out, although the extent of the t right 

 crescent and penumbra was very much increased. 



Declinations of Stars for Rf.duction of Variations 

 IN Latitude. — No. 263 of the Astronomical J ournal cox>X^\n% 

 the declinations of thirty-six stars, which have been obtained 

 with the prime-vertical transit of the United States Naval 

 Observatory. The observations were made for the determina- 

 tion of the constant of aberration, and consequently at the periods 

 of maxima aberration effects, but their present publication, as 

 Prof. S. J. Brown states, is owing to the "many requests for 

 the observed declinations of these stars for use in discussing 

 probable secular and periodical changes in latitude." The 

 stars in this list are comprised in the zone 36° 37' — 38° 40'. 

 The communication contains a brief account of the methods of 

 reduction employed, together with a reference to the instrumental 

 adjustments. 



The same number of the Journal contains also some results 

 of the observations of a Lyrae, made during the years 1862-67 

 with the same instrument as mentioned above. The discussion 

 of these observations was first made when Euler's value of 306 

 days for the periodical variation of the latitude was in vogue, 

 but Prof. S. Newcomb, in the present case, has taken Mr. 

 Chandler's new value, and gives, briefly, the following results : — 



Mean declination of a Lyrae for 1865 'O,! 



assuming the latitude of the centre of the ^38° 39' 35" '56 



Ob>ervatory to be 38° 53' 39" "25 j 



Correction to Struve's constant of aberration... + o"'oo6 



Hence, constant of aberration 20" '451 



Parallax of a Lyrae + o"24 



Coefficient of sun's azimuth in declination ... + o"'507 



Coefficient of sin N s= + o" 086 



Coefficient of cosine N c =■ - d'0%1 



the value of N being assumed zero at 1864*50, increasing 

 308° annually. 



The expression which he gives for the variation of the 

 latitude of Washington is 



S</> = o"-i22 cos 308° (/ - i864'94), 



the distance between the poles, or the semi-amplitude of the 

 variation of the latitude, being o"*i22. 



Comet 1892 Denning (March 18). — The following 

 elements and ephemeris are given for this comet in the 

 Astronomische Nachrichten, No. 3089, computed from three 

 observations made at the Hamburg Observatory : — 



T = 1892 May 11-22042 Berlin M.T, 



w = 129 18 34*4 

 8 = 253 25 41-6 

 i = 89 42 4-3 

 log (/ = 0"2946i9; 



M. Equator i892'o. 



Ephemerts for 12//. Berlin M. T. 



1892. h.'^m'''s ^^^^' '°«''- •''S'i- Br. 



May 19 3 49 27 +S2 13-5 



20 52 26 51 577 



21 55 22 51 41 '8 0-2947 o*4423 o-So 



22 58 15 51 25-9 



23 415 5« lo-o 



24 3 52 50 54-1 



25 6 37 50 38-2 0-2948 0-4466 0-79 



26 9 19 50 223 



The brightness at the lime of discovery is taken as unity. 



Comet 1892 Swift (March 6).— The elements and ephemeris 

 of this comet are given in the Edinburgh Circular (No. 26), 

 from which we make the following extract : — 



1892. 



Decl. 



\og £i. 



log!*-. 



01522 0-1035 o'53 



R..\. 



h. m. s. , / 



May 19 23 23 44 -f3i 52-2 



20 26 16 32 22-2 



21 28 47 32 51-6 



22 31 16 33 20-4 



23 33 44 33 48 7 



24 36 10 34 16-5 



25 38 34 34 437 01628 0-1166 0-47 



26 40 56 35 10-4 



The brightness at the time of discovery is taken as unity. 



The comet is situated in the constellation of Pegasus, and on 

 the 22nd will form very nearly an isosceles triangle with h Pegasi 

 and a Andromedce, the comet then lying nearly midway between 

 rj Pegasi and a Andromedse. 



NO. I 177, VOL. 46] 



GEOGRAPHICAL NOTES. 



M. Louis L(')CZV, in his annual address to the Hungarian 

 Geographical Society at the commencement of the current 

 session, expressed surprise that scientific geography was so little 

 appreciated in England. "It is sad to see," he said, "that, 

 despite the efforts of the oldest of Geographical Societies, the 

 great Universities of Oxford and Cambridge have not yet 

 established chairs of geography, and that lectureships even have 

 only been established with difficulty." 



In the Report of the Mississippi River Commission, the extent 

 of the levees confining the river below Cape Girardeau (Missouri) 

 is given as 1300 miles. During the high water of 1891, the 

 levees gave way in five places, and the total length of the 

 breaches made in the embankment was about one mile. By far 

 the most serious gap was that at Ames Plantation, opposite 

 New Orleans, which attained a width of 1665 feet, and a 

 maximum discharge of about 91,000 cubic feet per second. It 

 overflowed 2000 square miles, one tenth being cultivated land. 

 The cause of this crevasse was a badly constructed rice-flume, 

 and as the great Nita crevasse of 1890 had a similar origin, the 

 Commission has resolved to discountenance the use of such 

 flood-gates in future. All of the crevasses of 1891 put together 

 discharged less water than the Niia crevasse alone in the 

 previous year, and it was only one out of about fifty breaks 

 which occurred during the great floods. 



A new map of Dahomey, on the scale of i : 500,000, has been 

 prepared by M. A. L. d'Albeca, and published as a supplement 

 to the new journal. La Politujtie Coloniale, All available data 

 have been employed in its preparation, much being of course 

 derived from itineraries unchecked by observation. 



Captain Gallwey, Vice-Consul for the Oil Rivers 

 Protectorate, has succeeded in tracing a channel navigable for 

 canoes through the deltaic swamps between Benin and Lagos, 

 a distance of 160 miles. 



The Proceedings of the Royal Geographical Society for May 

 contains a letter from Mr. Gilbert T. Carter, Governor of Lagos, 

 describing a recent journey into the interior. From the summit 

 of a hill near Ode Ondo he obtained a magnificent view to the 

 south-east over a foreground of rocky forest- clad hills, backed by 

 a fine range of mountains about twenty miles away, which have 

 not previously been reported. The height of the most con- 

 spicuous summits is estimated to he from 5000 to 8000 feet 

 above sea-leveL 



THE VARIATION OF TERRESTRIAL 

 LATITUDES. 



TN a letter addressed to M. R. Radau by M. Antoine 

 ^ d'Abbadie, which appears in the March number of the 

 Bulletin Astronomiqtie, the writer gives an interesting his- 

 torical account of the work that has been done with regard to 

 this question. As it contains also some suggestions for future 

 work, the following rcsumS may be of service. 



