June lo, 1875] 



NA TURE 



After the vast expenditure of capital in the purchase of 

 the Cooke and Wheatstone patents, erection of lines oyer 

 the kingdom, station inauguration, and the incorporation 

 of the Company by special Act of Parliament, naturally 

 the promoters of the Electric Telegraph Company endea- 

 voured to create a monopoly in the transmission of 

 messages for the public. 



{To be continued) 



OUR ASTRONOMICAL COLUMN 

 The Total Solar Eclipse of 1886, Aug. 29.— This 

 eclipse will be a remarkable one, on account of the length 

 of duration of totality, which will not fall far short of that 

 of the eclipse of 1868, Aug. 18, though it unfortunately 

 happens that its track is mainly over the Atlantic Ocean, 

 and there will be no land station for physical observations 

 while the sun is hidden for the longest interval. The 

 elements of the eclipse are, very approximately, as 

 follows : — 

 Conjunction in R. A. 1886, Aug. 29, at oh. 57m. 377s. G.M.T. 



t57 50 51 '9 

 37 4-8 

 2 167 

 9 10 38-4 N. 

 9 17 23-9 N. 

 10 45'i S. 

 o 53'4 S. 

 61 20-5 



R.A 



Moon's hourly motion in R.A. 



Sun's ,, ,> 



Moon's declination 



Sun's ,, 



Moon's hourly motion in Dec!. 



Sun's ,, >, 



Moon's horizontal parallax 



Sun's ,, °^ 



Moon's true semidiameter 1642-9 



Sun's „ 15 5i'i 



The central eclipse begins Aug. 28, at 23h. 12m. 32s. 

 G.M.T., in longitude 79° 33'W., and latitude 9° 51' N., 

 and ends Aug. 29 at 2h. 36m. 28s. in longitude 47° I9 E-, 

 and latitude 21° Si' S., and the sun is on the meridian 

 centrally eclipsed in longitude 14° 13' W., and latitude 

 2° 58' N. The following are also points upon the central 

 line : — , . ^ 



Longitude. Latitude. 



66° 47' W , II 36 N 



61 I W : 12 6 N 



II 9 E II 5 S 



20 10 14 52 



21 39 15 25 

 25 5 E 16 36 S 



It would appear from this track that the only easily 

 accessible station where the sun will be at a sufficient 

 altitude will be at the southern extremity of the Island of 

 Grenada, in the West Indies ; for which point, assuming 

 its longitude 4b. 6m. 20s. W. and latitude 11° 59' N., we 

 find— 



H. M. S. 



Beginning of totality, Aug. 28, at 19 10 7 ) Local 

 Ending „ » 19 13 22^ mean times. 



The duration is therefore 31"- ^Ss-, and the sun's altitude 

 is about 20°. 



If we take for a point where the sun will be near the 

 meridian, longitude oh. 50m. 52s. W. and latitude 2° 8' N., 

 we have — 



H. M. S. 



Beginning of totality, Aug. 29, at o 8 48 ) Local 

 Ending „ „ o 15 14 i mean times. 



The duration of total eclipse, which is here nearly at its 

 maximum, is therefore 6m. 26s., and the sun at the time 

 is only f from the zenith. 



From this point the length of totality diminishes, until, 

 during the passage of central eclipse over Southern 

 Africa from near St. Philip de Benguela to the Mozam- 

 bique, it is comparatively short. It will be seen that the 

 central line runs considerably to the north of the islands 

 of Ascension and St. Helena. 



The middle of general eclipse occurs at oh. S4m. 30s. 

 G M.T. ; the sidereal time at Greenwich mean noon is 

 loh.'som. 27S-8, and the equation of time om. 46s. sub- 



tractive from mean time, figures which may facilitate a 

 further examination of the phenomenon. 



The Sun's Parallax.— Prof. Galle, Director of the 

 Observatory at Breslau, in a letter to M. Leverrier, gives 

 the definitive result of his discussion of observations of 

 the minor planet Flora (Hind, 1847, Oct. 18) in the 

 autumn of 1873, at observatories in both hemispheres, 

 with the view to a determination of the solar parallax. 

 The receipt of particulars concerning some doubtful 

 observations at Melbourne and other stations had en- 

 abled him to apply some small corrections, by which, 

 however, the value of the sun's parallax published in 

 No. 2,033 of ^^ Astronomische Nachrichteti is but very 

 slightly changed. Prof. Galle now finds from eighty-one 

 corresponding observations between the two hemispheres, 

 forty-one stars of comparison to the north of the planet 

 and forty to the south, that " the definitive result for the 

 solar parallax should be fixed at tt = 8"-873, with a very 

 small uncertainty in the hundredths of the second." He 

 adds, that of ninety-six corresponding observations in 

 all, he had excluded fifteen on account of some discord- 

 ances arising from imperfections in the southern instru- 

 ments, but even if these fifteen observations were included, 

 the value is only changed to 8"-878. Prof. Galle is 

 engaged in the composition of a memoir giving full 

 details of his investigation. He remarks upon the 

 close agreement of his result with that obtained by 

 the numerous and very exact measures of the velocity 

 of light, by M. Cornu, at the Observatory of Paris, 

 with the theoretical determination of M. Leverrier 

 from the perturbations of the planet Mars, and with 

 M. Puiseux's first result from observations of the 

 transit of Venus at Pekin and St. Paul Island. He 

 directs attention to the circumstance, that another 

 favourable opportunity of applying the method which has 

 furnished a value for the sun's parallax by observations 

 of Flora in the northern and southern hemisphere, so 

 nearly in agreement with values deduced in other ways, 

 will be afforded about the opposition of Eurydice (Peters, 

 1862, Sept. 22), which occurs on the 20th of September 

 next, when the planet will be a bright ninth magnitude. 

 It will be in perihelion early in the previous month, and 

 at its nearest approach to the earth on Sept. 1 3, will be 

 distant less than 0-878 of the earth's mean distance from 

 the sun. Prof. Galle hopes to secure on this occasion the 

 co-operation of the astronomers who have taken part 

 in the observations of Flora. 



The Minor Planets.— On comparing elements of 

 this group as known to the present time, it appears that 

 Flora h&s the shortest period of revolution, 1193 days, 

 and of those which have been satisfactorily calculated, 

 Sylvia has the longest, 2374 days, the corresponding 

 mean distances, expressed in parts of the earth's mean 

 distance from the sun, being 2-201 and 3-482. The nearest 

 approach to the sun is mace by Pliocea, 1-787, while Freia 

 recedes furthest from him, the aphelion distance being 

 4-C02. We may add to these the following values near 

 the extremes of distance :— 



Polyhymnia has the greatest excentricity, 0-33998, and 

 Lonna the least, 0-02176 ; Pallas the greatest inchnation, 

 34° 42', and Massalia the least, 0° 41'. It will be seen 

 that the difTerence of distance from the sun betweer 

 Phocea in perihelion and Freia in aphelion is 2-215, cor- 

 responding to about 204,000,000 miles. 



M. Leverrier's Bu^fetin International of June 5 cor- 



