656 



NATURE 



[Oct. 31, 1889 



routine work in connection with the maintenance of the system 

 of colonial time signals ; a number of observations of the zenith 

 distances of northern stars and circumpolars both above and 

 below the Pole, for the comparison of declinations as observed 

 at Observatories on either side of the equator ; and some pro- 

 ;gress as having been made in the observation of pairs of equi- 

 zenith distance stars for the determination of the latitude of the 

 Observatory. The various computations undertaken at the 

 •Observatory have been pushed forward much more zealously. 

 These embrace the comparison of the Greenwich lunar obser- 

 vations for the decade 1878-87 with Hansen's lunar tables ; 

 the reduction of Mr. Campbell's observations of the lunar crater 

 Murchison A, made at the Arkley Observatory in the years 

 1882-84; and the reduction of the third year's tidal observations 

 at Durban. 



The Spectrum of R Andromeda. — Mr. Espin, who has 

 ■recently discovered bright lines in the spectra of several long- 

 period variables of Secchi's third type, has added another to the 

 ■list ; R Andromedse, at the maximum just passed, showing a 

 number of bright lines, F being very bright, so bright as to 

 appear to project beyond the spectrum. The spectrum of the 

 star had manifestly undergone a great change from the time 

 when Duner made the very thorough study of it which he has 

 ■recorded in his work on " Les Etoiles a Spectres de la Troisieme 

 Classe." Five of the seven variables included in Mr. Lockyer's 

 Species 10 of this type have now shown bright lines at maximum, 

 whilst Gore's Nova Orionis, which should certainly be included 

 in the same species, would make a sixth. The two stars in 

 which bright lines have not yet been observed are R Leonis 

 Minoris and a Herculis. 



Comet 1889 d (Brooks, July 6). — The following ephemeris 

 is in continuation of that given in Nature for October 3 

 (p. 550) :— 



Ephemeris for Berlin Midnight. 



ASTRONOMICAL PHENOMENA FOR THE 

 WEEK 1889 NOVEMBER 3-9. 



/TpOR the reckoning of time the civil day, commencing at 

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



■is here employed.) 



At Greenwich on November 3 

 Sun rises, 7h. om, ; souths, iih. 43m. 40-4S. ; daily increase 



of southing, 0-53. ; sets, i6h. 28m. : right asc. on meridian, 



I4h. 35 -4m. ; decl. 15° 13' S. Sidereal Time at Sunset, 



I9h. 2im. 

 Moon (Full on November 7, i6h.) rises, I5h. 30m. ; soutls, 



2ih. im. ; sets, 2h, 45m.*: right asc. on meridian, 



23h. 54 •5m. ; decl. 6° 7' S. 



Planet. 



Mercury,. 

 Venus ... 

 Mars ... 

 Jupiter .., 

 Saturn ... 

 Uranus... 

 Neptune.. 



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

 that of the following morning. 



Saturn, November 3. — Outer major axis of outer ring = 39"'3 ; 

 outer minor axis of outer ring = 5" -8 : southern surface visible. 



Meteor-Showers. 

 R.A. Decl. 



Near 7 Camelopardalis... 55 ... 71 N. ... Swift. 



,, \\i& Pleiades 60 ... 20 N. ... The Taurids. 



,, e Ursse Majoris ... 143 ... 50 N. ... Very swift. 

 From Lacerta 346 ... 52 N. ... Rather slow. 



Nov. 



5 Cephei 



... 22 25-0 ... 57 51 N. ... ,, 



M signifies aiaximum : m minimum. 



SEISMOLOGICAL WORK IN JAPAN} 



'T^HE seismological work which has been accomplished in 

 Japan is to a great extent described in fourteen small 

 volumes published by a Society which was organized in 1880 to 

 study phenomena connected with earthquakes and volcanoes. 

 This Society is called the Seismological Society of Japan. An 

 epitome of a portion of this work is to be found in nine Reports 

 on the volcanic phenomena of Japan issued by this Association. 

 A glance at the first few volumes published by the Seismological 

 Society shows that the attention of its members was directed 

 towards seismometry. For several years attempts were made 

 to record earthquakes by using the old types of earthquake 

 instruments, such as columns balanced on end, bowls or tubes 

 filled with liquid, pendulums with pencils or pointers writing on 

 paper or smoked glass. The records obtained from instruments 

 of this order were, however, gradually recognized as being too 

 indefinite ; the instruments indicated that shakings had taken 

 place, but they failed to measure them. All investigators 

 recognized that to measure the movement of the earth it was 

 necessary, while the movement was going on, to obtain a steady 

 point or platform relatively to which the motion might be 

 measured. By the patient labours of investigators in Japan, 

 which have extended over many years, this has been accomplished, 

 and we now have pendulums and other forms of instruments 

 which for small displacements are in neutral equilibrium, so that 

 when the frames carrying these instruments are shaken back and 

 forth or up and down there are certain portions of them which 

 remain at rest. From these steady points pointers project which 

 write the movements or magnified representations of these 

 movements upon suitably prepared surfaces. 



From the simple pendulum and style, tracing its movements in 

 sand, and costing but a few pence, elaborate instruments, embrac- 

 ing many new mechanical contrivances, and writing their move- 

 ments with delicate siphons on continuously running bands of 

 paper, have gradually been evolved. With the assistance of 

 these instruments many thousands of diagrams, each of which 

 represents in absolute measures the back and forth motions of 

 the ground during an earthquake, have been obtained, and we 

 now know the true nature of earthquake movement. We have 

 learnt that, in many earthquakes which are quite perceptible 

 and sometimes even alarming, the amplitude of motion may 

 not exceed a millimetre, while if it reached 25 millimetres, or an 

 inch, we might expect cities to be ruined. 



The results which have flowed from a study of these diagrarris 

 are numerous and interesting. We now know that the direction 

 of movement in any given earthquake is continually varying. 

 At one moment a point on the iurface of the earth may be 

 moving north and south, and the next moment it may be 

 moving east and west, while at other times it may be following 

 a path too intricate to be easily described. 



More interesting observations relate to the period and ampli- 

 tude of the earth's motion, from which may be calculated the 

 destructive power, which depends partly on the maximum 

 velocity and partly on the suddenness of movement. Some 

 earthquakes commence with preliminary tremors, which have 

 been recorded with a frequency of eight or ten waves per second. 



The back and forth movements of considerable amplitude 

 which constitute the shock or shocks in an earthquake usually 

 have a period of one or two seconds, while the ordinary back 



' A Paper, by Prof. John Milne, of the Imperial University of Japan, 

 Tokio, read at ihe British Association. 



