December 1, 1886.] 



♦ KNOWLEDGE ♦ 



THE SOUTHERN SKIES. 



DECEMBKR, JASUAKV, AND KEBRUARV. 



3 HERE are few features of a journey »outh 

 more interesting than the change by which 

 night after night new stars are brought 

 into view. IjOw clown towards the southern 

 liorizon constellations unknown in our 

 northern heavens are seen hour by hour, 

 night after night. As the stout ship ploughs 

 her way onwards the star groups already 

 seen creep gradually higher in the southern skies, fresh 

 groups taking their place along the southward verge of the 

 star canopy. The stars which had been overhead at home 

 pass downwards towards the north ; the stars which had 

 been high in the southern skies pass overhead, and are seen 

 northwards ; and the stars which had been high towards 

 the north sink lower, or pa.ss beneath the northern horizon. 

 But changes such as these attract less notice than the 

 changes towards the south, because they bring no new stars 

 into view, whereas not a clear night comes in any voyage 

 towards the south but stars never seen in our latitudes 

 can be recognised low down in that dii'ection. It is 

 as when we climb a rounded hill, seeing at each step new 

 features beyond its outline, only that though we are 

 rounding a globe surface in travelling we cannot bu said to 

 climb, seeing that our distance from the centre remains 

 unchanged save for the oblateness of the earth's spheroidal 

 globe. 



It has seemed to me well (the idea occui-red long after this 

 work was well entered on) to use these southern maps to 

 illustrate the change of the heavens towards the south in 

 southward travelling, as well as to show (which was their 

 primary purpose) the aspect of the southern heavens, month 

 by month and hour by hour, in southern latitudes. Thus these 

 maps may serve as companions for travellers from northern 

 to southern regions, enabling them, at whatever time their 

 journey may take place, to lecognise the new stars rising 

 steadily above the southern horizon as they themselves 

 advance steadily southwards. 



Suppose, for instance, that the traveller is on his way 

 south from the latitude of the middle of the British Isles, in 

 the month of February. The map of the southern skies in 

 the present number of Knowledge presents in its upper half 

 the southern half of the heavens as seen at the houi-s named 

 underneath the map, in England and Wales, Scotland and 

 Ireland, or in any part of the northern hemisphere in the 

 same latitudes. Of coui'se this is only absolutely true for \ 

 one exact latitude, viz., 52° north, but it is quite near 

 enough for ordinary study of the star-strewn heavens 

 between latitudes 45° and 60° north. The point marked z, 

 which, ^s the map is intended to be used in the southern 

 hemisphere, represents the north point of the horizon, is the 

 zenith, or point overhead, for the northern use of the map I 

 am now considering. The point E is on the horizon due east, 

 the point w is on the horizon due west — in both uses of the 

 map ; but whereas for the southern use e o w represents a 

 semicircle passing from east at E overhead at o to west at w, 

 in the northei-n use it represents the horizon from east at E 

 to due south at o and to west at w. 



In England, then, we have at the time and hours named 

 under the map, Orion at hLs highest nearly due south. 

 Almost overhe;id is the night star Capella, a of the Con- 

 stellation Auriya. Along the horizon we have Hydra in the 

 south-east, a great vacant region all around, a part of the 

 poop of Argo, Canis the Greater Dog, Colunibu the Dove, 



Eridanus'. the Great River, and the upper half of the body 

 of Cetv-s the Sea Monster.* 



Travelling southwards, it is the stars below o in our map 

 which at the times named telow the map are coming 

 gradually into view. More and more of Argo rises above 

 the horizon somewhat to the east of the south point, more 

 and more oi Eridfuius towards the south-west. The south 

 point of the horizon advances along the south pole of the 

 heavens as the traveller advances towards the south, and at 

 a rate varying precisely as liis does, for the plan of the pro- 

 jection is such that equal distances on the star sphere are 

 represented by equal distances along all diameters of the 

 map. The varying southern horizon is not shown in the 

 maps, but can easily be pictured as an arc (not far from 

 circulai-) running from e to w through the south point of 

 the horizon, advancing southwards as described. 



After travelling southward to about 38° north, the bright 

 star Canopus comes into view somewhat east of south. At 

 about 25° north latitude the Greater Magellanic Cloud 

 begins to be seen due south. Soon after the whole of this 

 strange congeries of stars and star clouds has become visible, 

 the southern horizon, shifting southwards, passes below the 

 whole of Arijo on the eastern side, and the whole of Eridamis, 

 even to the bright Achernar, on the western. As thus seen 

 Argo certainly suggests no resemblance to a ship, unless the 

 imagination rises to the thought of the stern half of a ship 

 plunging almost vertically downwards beneath the waves. 

 But with that idea, and including half the constellation 

 Canis and the whole of Columba, remembering also the 

 form of the old-fashioned ships such as Egyptian, Greek, and 

 Roman carvings show them, we have about as fine a star- 

 drawn picture of a foundering ship as could well be expected. 

 It adds to the interest with which we thus contemplate the 

 conception of very ancient imaginations, indeed, to consider 

 that the great star-ship thus seen in our days so strangely 

 situated was like a ship drawn stern foremost into harbour 

 (that is, only slightly slanted) in the days of Eudoxus and 

 Aratus. The Great Ship was on an even keel, and the whole 

 of it — from its poop, where we now see the Greater Dog, to 

 its bows, where we now see the Centaur — was well above the 

 horizon of the Great Pvramid and Babylon — nay, of Athens 

 and of Rome — fifty-two or fifty-three centuries ago, when the 

 Great Pyramid was built. 



At the equator the south pole rises above the horizon — 

 we cannot say it comes into view, for it is not marked by 

 any conspicuous star. At this time the Southern Cross, 

 Crux, is rising into view in the south-east, but not in that 

 position which suggests the idea of a cross ; indeed a 

 traveller who had reached the equator at the season con-e- 

 sponding to Map II., and only observed the heavens dui-ing 

 the hours before midnight as he travelled south, could not 

 at all have recognised the cross-like appearance of this 

 small constellation ; nor could he recognise it afterwards. 

 The Southern Cross, paradoxically enough, is only properly 



* It should be noticed that equal distances aloDs: the horizon are 

 represented by equal distances along E o w. Moreover, those star- 

 groups to which we direct chief attention in this use of the map, viz., 

 tliose low down cowards the south (near O therefore) are very little 

 distorted. It is near the circumference of all these maps that the 

 chief distortion, resulting from showing a hemisphere in a circular 

 map, comes in. AVe have a fair picture of the horizon constellations 

 Canis, Orion, Lt'pus, Columba, and Eridaiuis, in the second map of 

 our series. In this sense the maps of the present series will form a 

 useful supplement to the maps of my Star Primer, as those in like 

 manner will form to these ; seeing that the constellations near the 

 horizon are distorted in one set (as if stretched out parallel to the 

 horizon) and undistorted in the other, and vice versa. Note further 

 that the maps published each month serve as well (though for 

 different hours) for England, where they appear at once as for 

 southern places, which they only reach two months or so later. 



