April 2, 1900.] 



KNOWLEDGE 



83 



ban, lies midway between Zeta Ursse Majoris auct 

 Gamma Ursie Minoris. 



Starting from Epsilon Ursse Majoris, the star in the 

 Great Bear's tail nearest the root, and crossing the North 

 Pole, we find on the further side of the Polo, right upon 

 the sparkling background of the Milky Way, here almost 

 at its broadest, five stai-s in the shape of a W, the prin 

 cipal stars of the constellation Cassiopeia, the " Lady m 

 her Chair. " At midnight on the first of April, this group 

 is low down in the north; the W being, as it were, 

 written in a dropping line from left to right, that is 

 from west to east, as if scrawled by a tired writer. The 

 lettering of the stars is nearly but not quite in the re- 

 verse order of writing. Reading from left to right they 

 come Epsilon, Delta, Gamma, Alpha, Beta, the three 

 last named being distinctly brighter than the other two. 



Starting from Cassiopeia, and following the Milky 

 Way towards the west, we find a number of stars 

 mai-king out the spine of the Galaxy, and bending down 

 in an elegant curve to the bright somewhat yellow star 

 m the north-west. The stai's in this curve are the prin- 

 cipal members of the constellation Perseus, and the 

 bright yellow star at the end of the curve is Cai)ella. 

 Alpha in the constellation Auriga. It is a star im 

 possible to mistake, since close beside it is a very pretty 

 little right-angled triangle of moderately bright stars. 



Following the Milky Way towards the east, we find 

 a bright star in the centre of the Galactic stream and 

 about as far from Cassiopeia on the east as Capella is 

 on the west. This is Deneb, Alpha in the constellation 

 Cygnus, and it forms the head of a magnificent cross of 

 slars. A little further along the Galaxy we coma to 

 another star not quite so bright, but of a slightly warmer 

 tinge. This is Gamma, the star which marks where the 

 two beams of the cross intersect. Above and below 

 Gamma are other stars, making up a magnificent 

 curving line, the transvei-se beam of the cross, or, 'f we 

 prefer so to regard it. the upper outline of the out- 

 stretched wings of the Swan. A straight line from Alpha 

 through Gamma and along the spine of the Milky 

 Way, leads through a succession of considerable stars to 

 Beta, which marks the Swan's beak, or the root of the 

 cross. 



Somewhat above the Swan and further to the east, 

 and making very nearly a right-angled isosceles triangle 

 with Beta and Gamma, the right angle being at Beta, 

 is a splendid steel blue star, Vega, the rival of Capella 

 in brightness, the two being claimants for the premier- 

 ship of the northern heavens. The five bright stars 

 ■v^hich wait upon Vega in its immediate neighbourhood, 

 and of which the nearest, Epsilon, is a very close double 

 to keen sight, make up with it the constellation of Lyra, 

 a constellation which lies for the most part outside the 

 circumpolar circle for the latitude of London. 



The chief guiding stars, therefore, for the northern 

 keavens, are the well-known Plough, the scarcely less 

 distinctive little W of Cassiopeia on the < pposite side 

 of the Pole, and the two great brilliants between ihem 

 on the right hand and on the left, Capella and Vega. 

 All these are continually visible for Scotland and the 

 North of England; for the southern part of our is'and 

 Vega is lost for a short time when due north. 



Only one important group among the northern con- 

 stellations has now been left undescribed. This is 

 Cepheus, the Ethiopian king, a constellation of no great 

 brilliancy or distinctiveness, and lying between the 

 Dragon and Ca.ssiopeia; the feet of the figure are sup 

 posed to stand on the Pole of the sky. 



The accompanying map shows the position of the 

 circumpolar region with regard to the north horizon at 

 midnight on the first of April. Tho figures ranged 

 round tho circumference of the map show the position 

 of tho north point of tho horizon for hourly intervals 

 of the day and night at that time of the year. For other 

 dates in the year we can find its position noarly enough 

 by remembering that for cvci^ month later in the year 

 that we take wc must also take two hours earlier in the 

 evening to obtain stars in the same position, or if W3 

 take a single day later in the year then wc must choose 

 our time four minutes earlier. 



EARTHQUAKE-SOUNDS. 



By CiiART.F.s Davison, sc.d., f.g.s. 



The .sound which accompanies an earthquake li;is rarely, 

 if ever, been described more graphically than bv an 

 obsei-ver of the Charleston earthquake of 188G. He was 

 at the time on the second floor of a lofty building in 

 Charleston when his attention was " vaguely attracted 

 by a sound that seemed to come from tho office below, 

 and was supposed for a moment to be caused by the 

 rapid rolling of a heavy body, as an ii-on safe or a 

 heavily laden truck, over the floor. Accompanying the 

 sound there was a perceptible tremor of the building, 

 not more maiked, however, than would be caused by 

 the passage of a car or dray along the street. For per- 

 haps two or three seconds the occurrence excited no 

 surprise or comment. Then by swift degrees, or all at 

 once — it is difficult to say which — the sound deepened 

 in volume, the tremor became more decided, the ear 

 caught the rattle of window-sashes, gas-fixtures, and 



other movable objects The long roll deepened 



and spread into an awful roar, that seemed to pervade 

 at once tho troubled earth and the still air above and 

 around. The tremor was now a rude rapid quiver, that 

 agitated the whole lofty, strong-walled building." Soon 

 " the floors were heaving underfoot, the surrounding 

 walls and partitions visibly swayed to and fro, the 

 crash of falling masses of stone and brick and mortar 

 was heard overhead and without, the terrible roar filled 

 the ears and seemed to fill tho mind and heart, dazing 

 perception, arresting thought . . .", until at last " the 

 uproar slowly died away in seeming distance. The 

 earth was .still, and oh! the blessed relief of that 

 stillness !"* 



Though the chief features of the earthquake-sound 

 are described in the above extract, its character varies 

 considerably in different earthquakes, in various parts 

 of the area of one and the same earthquake, and even 

 with individual observers in the same house. For several 

 years I have paid special attention to the phenomena 

 of earthquake-soundsf and have collected several thou- 

 sand descriptions, the types of comparison employed 

 belonging generally to one of tho classes mentioned 

 below. Occasionally, however, an observer is uncertain, 

 and quotes alternative types which may belong to dif- 

 ferent classes. But often the resemblance is so close 

 that he is himself deceived, and starts up from his chair 

 to see the unexpected carriage pass. 



(1) The most frequent references of all arc to passing 

 vehicles of various kinds, and, as a rule, to very heavy 

 ones, such as traction-engines, steam-rollers or waggons, 



» C. E. Dutton, Amer. Geol. Survey, Nintli -Innual Report, pp. 212-213. 

 t See a paper in tho VhiL Mag. for January, 1900,-of whi.-h the 

 prc\sent paper is an abstract. 



