March 22, i8i8] 



NA TURE 



495 



habits. He established a fish- farm on his own estate, and 

 watched over it for many years. He divides his subject into five 

 parts. In the first place, he discusses the fish supply of Bengal, 

 and in doing so shows that the supply is frequently not equal to 

 the demand — a fact due chiefly to the absence of skilled fisher- 

 men. And so it happens that at various seasons breeding and 

 unmatured fish are brought to market to meet the demand. The 

 second chapter treats of the best food for fish ; the third of 

 hatching and breeding, and the proper precautions to be taken 

 at those times. The fourth part deals with the question from a 

 commercial and speculative point of view. A little capital, the 

 author says, if wisely invested in pisciculture and in fisheries 

 produces a greater return than in any other industry ; for while, 

 as Prof. Huxley says, an acre of land will produce in the year a 

 ton of grain or two or three hundredweight of meat, the same 

 extent of water in a good fishing-ground will yield a greater 

 weight of fish in a week. The author begs of his countrymen 

 to pay attention to this much neglected subject ; he puts his 

 practical experience before them, and thinks, that in a country 

 like Bengal, where fish forms a large portion of the dietary of 

 the people, it is a pity that more is not known of this subject. 

 One of the most valuable portions of this little work is the fifth, 

 in which he gives a scientific description and classification of 

 almost all the known fish in the waters of Bengal, with their 

 Bengalee equivalents. 



The additions to the Zoological Society's Gardens during the 

 past week include two Stock-Doves (Cohimba anas), British, 

 presented by Lieut. -Colonel W. G. Dawkins ; a 02i'^2\ {Bihos 

 frontalis), born in the Gardens. 



OUR ASTRONOMICAL COLUMN. 

 Distribution of the Sunspots of 1886 and 1887. — 

 Prof. Spoerer points out in a short note in the Astronotnischc 

 Nachrichten, No. 2828, that the predominance of the southern 

 hemisphere over the northern as to the numbers and areas of 

 sunspots which they have displayed has continued throughout 

 the two years just past. It would seem, indeed, as if the maxi- 

 mum for the southern hemisphere had fallen later than for the 

 northern, for after the last return of the great group of November 

 12-25, 1882, the latter hemisphere became comparatively 

 quiescent for a considerable time, and from that date the pre- 

 dominance of the southern hemisphere has been almost uninter- 

 rupted, the displays it exhibited during the latter part of 1883 

 and the earlier months of 1884 being so considerable and so 

 numerous as to make the date of maximum the same for the sun 

 as a whole as for the southern zone. So in the decline since the 

 maximum, not only has the mean spotted area of the northern 

 hemisphere been scarcely more than half that of the southern, 

 but the running down in latitude has been more marked in the 

 former than the latter. Thus in 1884, the northern zones above 

 lat. 25° were already free from spots, whilst in the south the 

 zone 25° to 30° was still occupied. In 1886 spots had ceased to 

 be seen in the zones north of N. lat. 20°, but were still seen in 

 the corresponding southern belt ; whilst in 1887 they had almost 

 vanished from the zone N. lat. 15° to 20°, though still fairly 

 numerous at a like distance from the equator on the other side. 

 The actual distribution of the spots is shown by Prof. Spoerer in 

 the following table : — 



Year. Totals. 



-{-2o° -1-15° -fio° 4-5° 0° -50 -10° -15° -20° -25° N. S. 



1886 M 17 I 30 I 40 I 14 II so I 45 I 68 I 47 j 5 11 loi I 215 



1887 11 2 I 22 I 15 I 14 II 19 I 56 J 27 I 14 I II S3 I 116 



The Total Eclipse of the Moon, January 28.— By the 

 kindness of Dr. E. Lindemann we are enabled to give the 

 following further list of occultations observed during the total 

 eclipse of the moon on January 28 : — Amherst, U.S., 7 ; Clinton, 

 U.S., 3 ; Copenhagen, 25 ; Harvard College, U.S., 23 ; Madrid, 

 20; Montreal, 6; Moscow, 15; Nice, 24 ; Princeton, U.S., 8; 

 Toulouse, 13 ; Utrecht, 15 ; Washington, li ; West Point, U.S., 

 2. Th2 weather was also favourable at the Birkdale Observa- 

 tory, SouthpDrt, and at Berlin and Dun Echt ; but at the last 

 two Observatories, and also at Lord Rosse's, the occultations 

 were not observed. The sky was cloudy at Hereny, O'Gyalla, 

 Quebec, Rio Janeiro, Stockholm, and Vienna. 



Spectroscopic Determination of the Rotation 

 Period of the Sun. -Mr. Henry Crew, Assistant in Physics 

 at the Johns Hopkins University, has recently published {Ameri- 

 can Journal of Scienre, February 1888) a series of observations 

 made with a fine Rowland grating of 14,436 lines to the inch, 

 of the relative displacement of certain lines in the solar spec- 

 trum, as given by the opposite limbs, with a view to determine 

 the rotation period of the sun. The result which he obtained 

 from 455 settings in the course of observations ranging over four 

 months and a half, gives, for the mean equatorial velocity, 

 if - v" = 2 '437 ± 024 miles per second, corresponding to a 

 true period of 25 88 days. But an unexpected and remarkable 

 circumstance was brought out by the investigadon, in that the 

 observations seemed to show a gradual increase of daily angular 

 motion with higher heliographical latitude, whilst, as is well 

 known, Carrington found a decrease of such motion for the spots. 

 Mr. Crew gives for the equation of this change — 



V = 1-158 cos x° (I + 0-00335 X), 

 whence we have for the daily angular motion of any point in 

 the reversing layer — 



Q = 794' (i + 0-00335 X°). 

 whilst Carrington obtained for the sunspots — 

 = S65' (i - o'lgi sin ix°)- 

 The greate-t irregularities in the value of v' - v" occurred be- 

 tween the latitudes 15° and 25°, i.e. in the chief spot zone. 



It should be added that different lines gave different values of 

 v' - v", with nearly as large a range as the different latitudes 

 did, but there appeared to be no connection between the order 

 of the velocities and the order in which the elements causing 

 the lines observed are generally supposed to be distributed in 

 the solar atmosphere. The double line, 1474 K, of which one 

 component is due to iron, and the other is the lineof the corona, 

 gave no evidence of variation in width on one limb, as compared 

 with the other, so if the two lines be produced by absorption 

 from different laye'S, those layers cannot be drifting with 

 respect to each other at a higher rate than one-third of a mile 

 per second. 



The spectrum of the fourth order was used throughout. 

 Attempts were made to measure the relative displacement of 

 the Dg line, as given by opposite limbs, but with this dispersion 

 the definition was not sufficiently good to permit satisfactory 

 measures of the line to be made. 



New Minor Planet. — A new minor planet. No. 273, was 

 discovered on March 8, by Herr Palisa at Vienna. This is 

 Herr Palisa's sixty-first discovery. 



ASTRONOMICAL PHENOMENA FOR THE 



WEEK 1888 MARCH 25-31. 

 /■pOR the reckoning of time the civil day, commencing at 

 V •^ Greenwich mean midnight, counting the hours on to 24, 

 is here employed. ) 



At Grecnuiich on March 25 

 Sun rises, 5h. 51m. ; souths, I2h. 5m. 54-3s. ; sets, i8h. 20m. : . 

 right asc. on meridian, oh. I9'4m. ; decl. 2° 6' N. 

 Sidereal Time at Sunset, 6ti. 34m. 

 Moon (Full, March 27, 22h.) rises, I5h. I2m. ; souths, 

 22h. 28m.; sets, 5h. 29m.*: right a-c. on meridian, 

 loh. 43'4m. ; decl. 10° 51' N. 



Right asc. and declination 

 Planet. Rises. Souths. Sets. on meridian. 



h. m. h. m. h. m. h. m. . / 



Mercury.. 5 10 ... 10 27 .. 15 44 ... 22 40-8 ... 9 9 S. 

 Venus ... 5 10 ... 10 23 .. 15 36 ... 22 36-7 ... 9 59 S. 

 Mars ... 20 12*... I 34 ... 6 56 ... 13 460 ... 8 10 S. 

 Jupiter ... 23 54*... 4 6 ... 8 18 ... 16 i8-6 ... 20 25 S. 

 Saturn ... Ii 54 ••• 19 53 ••• 3 52*... 8 76 ... 20 48 N. 

 Uranus... 19 12*... o 47 ... 6 22 ... 12 58-8 ... 5 32 S. 

 Neptune.. 7 49 ... 15 3° •■• 23 11 ... 3 44-1 ... 18 6 N. 

 » Indicates that the rising is that of the preceding evening and the setting 

 .that of the following morning. 



Occultations of Stars by the Moon (visible at Greenwich), 



Corresponding 



angles from ver- 



March. Star. Mag. Disap. Reap. tex to right for 



inverted image, 

 h. m. h. m. o o 



28 ... 80 Virginis ... 6 ... 19 49 ••• 20 43 ... 10 230 

 31 ... i\ Librcc 6 ... I 20 ... 2 30 ... 6l 234 



