342 



NATURE 



{Feb, 15, 1877 



deep rea are different in structure and composition from known 

 ores of manganese. 



Eighth. — That we do not appear to have equivalents of the 

 rocks now forming in the deep sea far from land, in the geolo- 

 gical series. 



In conclusion, I have to acknowledge much assistance in these 

 investigations from all my colleagues, especially my indebtedness 

 to Sir Wyville Thomson and Mr. Buchanan. 



Since my return I have received many hints from Profs. Tait, 

 Geikie, Turner, Dr. Purves, Mr. Morrison, and other gentlemen. 



In much of the mechanical work which an examination of 

 these deposits has entailed, I have, both during the cruise and 

 since my return, had the assistance of Frederick Pearcey. 



OUR ASTRONOMICAL COLUMN 



New Comet. — M. Stephan, Director of the Observatory at 

 Marseilles, announces the discovery of a new comet by M. 

 Borrelly on the morning of the 9th inst. It is described as 

 bright, round, with a well-defined nucleus, and 3^ minutes in 

 diameter. The first complete observation gave for its position— 

 February 8 at i6h. 57ra. 58s. M.T. at Marseilles. 



Apparent Right Ascension I7h. 13m. 237s. 



,, North Polar distance 91° 28' 20" 



Diurnal motion in R.A. + im, 44s. ; in N.P.D. - 3° 7'. 



M. Borrelly was also the discoverer of the last unpredicted 

 comet, on December 6, 1874, in which year six comets were 

 observed ; in 1875 only two were observed, both known comets 

 of short period j in 1876 none. 



The Occult ation of Regulus on February 26, — The 

 occultation of a star of the first, or between the first and second 

 magnitudes, is a sufficiently uncommon phenomenon to attract 

 attention. Regulus will be occulted on the 26th instant while 

 the moon is at a considerable altitude, and to facilitate the calcu- 

 lation of the times of immersion and emersion at any place in 

 this country we will apply the very convenient method given by 

 the late Prof. Littrow for distributing such predictions over a 

 limited area. 



Putting the latitude of the place = 50° + /, and expressing 

 I in degrees, and the longitude from Greenwich = L, and ex- 

 pressing L in minutes of time, + if east, — if west, and found- 

 ing the equations upon direct computations for Greenwich, 

 Edinburgh, and Dublin, we find with the Nautical Almanac 

 elements, 



Time of Immersion = I2h. 47m"2 — [o'0095]/ + [9'5i9i] L 



„ Emersion = I3h. S3m-5 - [0-2188]/ + [9'3209] L 



Angle at Emersion 



from N. Point 



232°-8 - [0-185]/ - [9-468] L 



The quantities within brackets being logarithms and the result- 

 ing times for the meridian of Greenwich. 



The following are the circumstances of the occultation at a 

 few of our observatories ; Greenwich time throughout : — 



In B.C. 27, second year Ho-ping, in the tenth moon, between 

 the 20th and last day of the moon, Saturn distant from Regulus 

 1° (Chinese measure), Jupiter to the north-west 1°, Mars to 

 north-west 2°. 



The Chinese commenced their year at the new moon imme- 

 diately preceding the sun's entry into the sign Pisces, and their 

 months were lunar. Accordingly in B.C. 27 the first moon com- 

 menced soon after midnight on February 10, Greenwich time, 

 and the tenth moon on the evening of November 2 ; the time 

 indicated by the Chinese record is therefore probably between 

 November 23 and December 2. Perhaps some one may have 

 the curiosity to examine this reported conjunction of Mars, 

 Jupiter, Saturn, and Regulus. We can state positively that an 

 occultation recorded about forty years earlier, observed under 

 the same dynasty, Han, and at the same station, that of the 

 Chinese court at Si-gnan-fou, in the province of Chen-sy, actually 

 occurred, according to our latest tables, and at the hour recorded 

 in the Chinese annals. 



The Solar Eclipse of 1567, April 9. — Prof. Grant, in his 

 valuable " History of Physical Astronomy," remarks that "the 

 earliest eclipse which was unequivocally asserted to have been 

 annular was one which occurred in the year 1567." It was ob- 

 served at Rome by Clavius, of Calendar celebrity, who has 

 recorded that when the obscuration was greatest there still 

 remained round the moon's limb a very narrow ring of the solar 

 light. Kepler (" Ad Vitellionem") found from his tables the 

 sun would have entirely covered the moon, and hence considered 

 that the luminous ring, mentioned by Clavius, was in reality the 

 corona, visible during total eclipses of the sun. 



The elements of the eclipse of 1567 obtained upon a similar 

 system of calculation to that applied to other modem solar 

 eclipses in this column are as follow : — . 

 Conjunction in R.A. 1567, April 8d. at 23h. 17m, los. G.M.T. 



No other occultation of so bright a star, visible in this coun- 

 try, will take place until July 28, 1879, when Antares will be 

 occulted. 



Amongst the Chinese observations collected by the Jesuit 

 missionary, Gaubil, are a number of occultations of Regulus, 

 the earliest of which is dated March 16, a.d. 501. While re- 

 ferring to this star, we may mention a remarkable approximation 

 of several planets near it, which is also recorded in the Chinese 

 annals, and which, so far as we know, has never been examined. 

 As interpreted by Gaubil, the observation runs thus :— 



R.A 



Moon's hourly motion in R. A. 

 Sun's „ „ „ 



Moon's declination ... 

 Sun's „ 



Moon's hourly motion in deck 

 Sun's „ „ ,, 



Moon's horizontal parallax . . . 

 Sun's ,, „ 



Moon's true semi-diameter . . . 

 Sun's ,, „ 



26 30 57 

 33 8 



2 19 

 11,27 45 N, 

 10 58 57 N, 



9 6N. 



o 52 N, 



57 36 

 o 9 



15 54-0 

 15 417 



The sidereal time at Greenwich mean noon, April 9, was 

 ih, 47m, 8s, If with the above elements we make a direct cal- 

 culation of the circumstances of the eclipse at Rome we find a 

 very great eclipse little short of totality ; began at loh. 41m. os 

 A.M., ended at ih. 42m. 23s. P.M. mean times at Rome, magni- 

 tude 0-9972, so that the breadth of the crescent was about 2% 

 seconds. The eclipse would be total for a few seconds on the 

 central line in this longitude, the augmented semi-diameter of 

 the moon exceeding the sun's semi-diameter only i"-5 ; but our 

 result as ic stands may very well explain the words of Clavius, 

 the extremely narrow crescent of the solar disc still remaining, 

 added to the probable visibility of the brighter part of the corona, 

 giving to the naked eye the appearance of a narrow uniform ring 

 of light. 



New Minor Planet, — No, 172 of the group of small planets 

 was detected by M, 15orrelly at Marseilles on the Sth inst. ; at 

 I2h. 8m. its R.A. was loh. 35m. 36s., N.P.D. 80° so'-g, twelfth 

 magnitude. On the following night at gh. 58m. its R.A. was 

 loh. 34m. 46s., N.P.D. 80° 29' -3. 



METEOROLOGICAL NOTES 

 Meteorology of the Libyan Desert. — A second volume 

 of Gerhard Rohlfs' great expedition into the Libyan desert has 

 been recently published at Cassel, under the editorship of Dr. 



