HARDWICKE'S SCIENCE-GOSSIP. 



179 



fthe lofty hills appear as towering cliffs, and craggy 

 islands. And, when we turn to a geological map of 

 Norway, we find that it is almost entirely occupied by 

 ■Cambrian and Silurian rocks ; the coast of Norway is 

 geologically the same as the west coast of Scotland. 

 We may then infer that the Norwegian invaders chose 

 ■our west coast because of its similarity to their own, 

 and we know that the resemblance is due to geo- 

 logical structure. 



And can we offer a similar explanation with regard 

 to the Danish choice ? The country most thickly 

 peopled by the Danes extends from the mouth of the 

 Tees to the Naze in Essex. Of this, the region from 

 the Tees to the Great Ouse is the most thickly studded 

 with Danish names. Two-thirds of this latter extent 

 is composed of recent drift and alluvium, and the 

 remainder almost entirely of Liassic and Oolitic 

 rocks. Flamborough Head and the Norfolk coast are 

 •Cretaceous ; the remaining part, southwards to the 

 Naze, the Tertiary rocks of the London basin. Hence 

 we have on the line occupied by the Danish settlers 

 a large extent of flat coast, cliffs not lofty, and no 

 deep indentations such as we find on the west coast. 

 Looking at an ordinary map of Denmark, we are 

 struck at once by the peculiarity of its coast-line. The 

 sea penetrates into the heart of, and at times almost 

 ■ across, the country; narrow spits of land cut off, or 

 almost cut off, small areas of ocean ; lakes are thickly 

 studded over the interior, and there are no high 

 mountains. All this suggests an absence of the older 

 geological formations, and a land recently elevated 

 from the sea. And on consulting a geological map, 

 we find that with the exception of a few patches of 

 Cretaceous rocks, Denmark is entirely Tertiary. So 

 it appears the Danes chose that portion of the British 

 coast which most resembled their own low-lying 

 shores. 



Yet another geological element has exerted an 

 influence in determining roughly the ultimate extent 

 of territoiy occupied by the Danes. This influence is 

 due to that barrier of Magnesian limestone which 

 stretches with a gap of twenty miles immediately 

 south of the Tees, like a wall from the Tyne to 

 ,the Trent, where the latter begins to take its final 

 northern bend. In a roughly approximate way this 

 barrier has bound in the Danish settlers. Through 

 ■the gap on the south of the Tees the green of the 

 Danish district on the map swells out westward to 

 meet and mingle with the Norwegian blue, spreading 

 • eastwards from the coast of Cumberland. And again, 

 <where the magnesian barrier ends at the river Trent, 

 the Danish settlers have spread out south-west 

 towards the Bristol Channel. 



This coincidence, it has been hinted, is only 

 rough, but the two bulgings out westwards through 

 'the gap and below the wall are most striking. A 

 large portion of Central England to the west of 

 .it is, in fact, left comparatively free from Danish 

 influence on its place names. 



Such are the results which suggest themselves, on 

 a cursory comparison of the geological map with one 

 coloured according to the prevailing nationality, as 

 determined by place names. 



They show that geology has had some share in 

 deciding the areas to be occupied by the different 

 nations. The part which the geological structure of a 

 region has had in moulding the character and 

 physical development of the people opens out another 

 interesting field of inquiry. 



Corbridge-on- Tyne. 



GOSSIP ON CURRENT TOPICS. 

 By "\V. Mattieu Williams, F.R.A.S., F.C.S. 



\LUMINIUM. — The production of aluminium is 

 steadily progressing in the direction of cheapness. 

 If its future history shall correspond with the past 

 history of many other chemical manufactures, it may 

 ere long become sufficiently cheap to enter into the 

 composition of ordinary domestic utensils, and 

 largely to take the place of copper and brass. If it 

 thereby hastens the ruin of commercial conspirators 

 who are rigging the copper market, all respectable 

 men of business will be thankful to it. 



The combination of tenacity with lightness which 

 is the characteristic of this interesting metal, consti- 

 tutes its chief merit. A multitude of uses will arise 

 from this combination immediately the price is 

 sufficiently reduced. 



It should be remembered that its low specific 

 gravity is practically an element of cheapness. 

 Copper, bulk for bulk, is more than three and a half 

 times as heavy as aluminium, silver four times ; there- 

 fore aluminium at 3J. per lb. is practically as cheap as 

 copper at tenpence, seven aluminium kettles of given 

 size will weigh less than two of copper, besides the 

 economy in handling. Four aluminium spoons of 

 given size, will weigh less than one of silver. 



I should here correct a rather common mistake. 

 In newspaper references to this subject, the writers 

 frequently describe clay as alumina, or the oxide of 

 aluminium. Even in a well-established text-book on 

 geology, I find enumerated among the constituents of 

 rocks " alumina or pure clay," and in an old 

 Dictionary of Geology we are told that " When clay 

 is quite pure and unmixed it is termed alumina." 

 Pure clay h3s a far more complex composition. It is 

 a hydrated silicate of alumina, i.e. a compound of 

 solid water with the oxide of silicon and alumina. 

 Neither alumina nor silicate of alumina (whether wet 

 or dry) has the characteristic plastic properties of 

 clay. If clay were mere alumina, the problem of 

 making aluminium would be materially simplified. 



The Mandrake. — In a recent number of " The 

 Asclepiad " (2nd quarter, iSSS), Dr. Richardson has 

 an interesting article on this subject. The facts he 



