482 



♦ KNOWLEDGE ♦ 



[Dec. 12, 1884. 



amorous, much inclined to music and poetry, and ever 

 inventing masques and tournaments in honour of their 

 mistresses." 



" Pardon me, madam," said I ; " you are little acquainted 

 ■with the planet. Granada, in all its glory, was a perfect 

 Greenland to it ; and your gallant Moors, in comparison 

 ■with that people, -were as stu])id as .so many Laplanders." 



" But what do you think, then, of the inhabitants of 

 Mercury 1 They are yet nearer to the sun, and are so 

 full of fire that they are absolutely mad. I fancy they 

 have no memory at all, like most of the negroes, that 

 they make no reflections ; and what they do is by 

 sudden starts, and perfect haphazard. In short. Mercury 

 is the bedlam of tlie universe : the sun appears to them 

 much greater than it does to us, because they are much 

 nearer to it than we : it sends them so vast and strong a 

 light that the most glorious day here would be no more 

 with them than a declining twilight. I know not if they 

 can distinguish olyects ; but the heat to which they are 

 accustomed, is so excessive, that they would be starved with 

 cold in the torrid zone. Their year is but three months ; 

 but we know not the exact length of their day, because 

 Mercury is so little, and so near the sun : it is (as it were) 

 lost in his rays, and is very hardly di.scovered by the 

 astronomers ; so that they cannot observe how it moves on 

 its centre ; but because it is so little, fancy it completes its 

 motion in a little time : so that by consequence the day there 

 is very short, and the sun appears to them like a vast fiery 

 furnace at a little distance, whose motion is prodigiously 

 swift and rapid, which is so much the better for them, as 

 it is evident they must long for night* ; and during their 

 night, Venus and the earth (which must appear conside- 

 rably big) gives light to them. As for the other planets 

 which are beyond the earth, towards the firmament, they 

 appear less to them in Mercury, than they do to us here, 

 and they receive but little light from them, perhaps none at 

 all : the fixed stars likewise seem less to them, and some of 

 'em totally disappear, which, were I there, I should esteem 

 a very great loss. I should be very uneasy to see this 

 large convex studded with but few stars, and those too of 

 the least magnitude and lustre. 



" What signifies the loss of a few fixed stars ? " says the 

 lady ; " I pity them for the excessive heat they endure ; 

 let us give them some relief, and send Mercury a few of 

 the refreshing showers they have sometimes four months 

 together in the hottest countries, during their greatest 

 extremity." 



" Your fancy is good, ]\Iadam," reply'd I ; " but we 

 will relieve 'em another way. In China there are coun- 

 tries which are extremely hot by their situation ; yet in 

 July and August are so cold that the rivers are frozen : 

 the reason is, they are full of saltpetre, which, being ex- 

 hal'd in great abundance by the excessive heat of the sun, 

 makes a perfect winter at midsummer. We will fill the 

 little planet with saltpetre, and let the sun shine as hot as 

 he pleases. And yet, after all, who knows but the inhabi- 

 tants of Mercury may have no occasion either for rain or 

 saltpetre ? If it is a certain truth that Nature never gives 

 life to any creature, but where that creature may live : 

 then, thro' custom and ignorance of a better life, these 

 people may live happily." 



(To lie continued.) 



It is stated that the January number of the Cornhill Magazine 

 will contain an .irticle upon Charles Dickens, ivritten by his eldest 

 daughter, entitled " Charles Dickens at Home," -with special re- 

 ference to his relations with children. 



* Only then their nights TTOuld be correspondingly short : bnt 

 perhaps they work at night and hide in caves by day. — R. P. 



EAMBLES WITH A HA]MMER. 



By W. Jerome Harbison, F.G.S. 

 GEOLOGY OP CEICCIETH AND PWLLHELI (continued). 



ABOVE the Arenig slates we come to the Bala Beds — 

 coarse black and blue slates and shales, with occa- 

 sional bands of sandstone — which form nearly all the 

 surface of the Lleyn peninsula, except where they ■wrap 

 round, or are pierced by, rocks of an igneous character. 

 There are many exposures of the Bala beds in quarries, 

 cuttings, and clifls ; and in such spots it is almost always 

 possible, by patient search, to find such characteristic fossils 

 as corals, trilobites, and brachiopods. The roadside cuttings 

 near Pwllheli, the grounds of Boduan Hall, Crugan near 

 Llanbedrog, and Plas-hen, may be named as good localities 

 for fossil-hunting. The coarseness of the sediment and the 

 abundant evidence of contemporaneous life, indicate that 

 the Bala beds were deposited in a shallow sea. This sea^ 

 bottom ■nas not so frequently disturbed by volcanic 

 eruptions as the part which lay further east, where — in 

 Snowdon, for example — we have alter notions of fossiliferous 

 strata of Bala age with lava flows and consolidated ash- 

 beds. But those igneous rocks, which in Lleyn are found to- 

 be connected with the Silurian strata, are intrusive in 

 them, cutting across the beds, and altering the rocks above, 

 as well as those below. Such intrusive masses must 

 necessarily be of later date than the strata -which they 

 traverse. 



Fig. 1. — lloel-y-gest. 1. Lingnla Flags; 2. Tremadoe Slates; 

 3. Arenig Beds ; 4. Greenstone Intrusive in Arenigs. 



The thickness of the Bala beds of Lleyn is unknown, but 

 is probably less than 2,000 feet. The strata have no 

 regular dip, but undulate over the surface of the peninsula, 

 so that they cover ajvery large area, hiding all but a narrow 

 fringe of the Cambrian and Arenig rocks beneath them, 

 and lapping round the harder masses of igneous rocks which 

 rise up as hUls. The efieet is very striking when we stand 

 on any of these eminences, and look across the low plain of 

 the Bala beds to the distant hills. All the high points owe 

 their present superiority in altitude to the greater hardness 

 of their rocks, which has enabled them to resist better the 

 wearing-down forces of sea and river, rain, frost, and 

 ice. The height of the hills is from 900 ft. (Cam Boduan) 

 to 1,887 it. (Yr Eifl), while the surface of the plain of Bala 

 beds from which they rise does not average more than 

 400 ft. above sea-level. The Bala beds are the newest, or 

 latest-formed, of the regularly stratified rocks which occur 

 in the peninsula of Lleyn. 



The Surface Deposits. — Under the name of Drift we 

 include all the relics of the last glacial period — the stones, 

 clay, sand, ic, which formed the moraines of the ancient 

 glaciers. Some quarter of a million years ago, it appears, 

 from causes partly cosmical, but, perhaps, in part geo- 

 graphical, the northern ice-cap of this planet stretched 

 southwards to somewhere near lat. 50° in Western Europe. 

 The mountains of Wales then furnished a gathering ground 

 for important ice-sheets, which radiated in every direction 

 from the hills. But the glaciers of Cumberland were still 

 larger, and, sweeping southwards, they arrested and 

 deflected the northerly flow of the Welsh ice ; then, grinding 

 on southwards, they excavated a long narrow valley, which 

 now forms the Menai Straits; or, as Ramsay forcibly puts it, 



