7-uly2S, 1889] 



NATURE 



299 



Make-believe. 



I CAN well believe in Sally meaning a joke. Animals have 

 a keen sense of '* making believe " which is the essence of play. 

 A child's first game is bo-peep — a make-believe. When a pair of 

 friendly dogs have a jolly tussle, they make believe to engage in 

 deadly combat. 



A striking instance of this occurred to me some years back. I 

 gave a dead mouse to a kitten. It was the first time she had 

 seen one, and she sniffed at it inquisitively before deciding on 

 tossing it about. A pair of slippers lay on the floor. She 

 dropped it into one of them, and iww^rt'£a/f/)' proceeded to look 

 for it most zealously in the other slipper, till I took up the first, 

 which contained her booty ; then she showed that it was no real 

 lack of memory that had sent her on the bootless search. 



The law allowed to game, when hunted for recreation, is 

 perhaps the most marked evidence of the make-believe element 

 which is to be found in the play of civilized adults. 



Dublin, July 16. Marcus M. Hartog. 



Dogs and Fire. 



An unrecorded type of the pluck of the fox-terrier was demon- 

 strated to me recently. A young dog two or three years old, 

 the property of Mr. Doyle, of Loretto Terrace, Bray, goes for fire 

 with as much zeal as any of his race go for rats. When a news- 

 paper thoroughly ablaze is thrown down, he stamps upon it with 

 frequent short rushes till it is extinguished, and then worries 

 the scorched remains before asking for a fresh opportunity. He 

 gets excited and keen on being shown a crumpled newspaper or 

 a match-box. 



The possibility thus shown of educating dogs to tackle fire 

 gives additional point to my friend Dr. Sigerson's published 

 suggestion to use dogs as companions to night-watchmen, based 

 on their keenness of scent. Marcus M. Hartog. 



Dublin, July 16. 



" The Theorem of the Bride." 



Referring to the last paragraph of the review of my " Greek 

 Geometry from Thales to Euclid" which appeared in Nature 

 of June 20 (p. 172) it may interest some of your readers to know 

 that since the publication of my book I have found the expres- 

 sion — tJ) Trjs pv/j.(l>r]s Qeoiprifxa — in the Scholia on the " Ele- 

 ments of Euclid." See " Euclidis Elementa," ed. Heiberg, 

 vol. v. p. 217, Lipsiae, 1888. 



The expression seems to have been a common name of 

 Euclid i. 47. George J. Allman, 



Belsito, Milford, Lymington, July 18. 



RECENT RESEARCHES INTO THE ORIGIN 

 AND AGE OF THE HIGHLANDS OF SCOT- 

 LAND AND THE WEST OF IRELAND.^ 



I. 



''pHE records of geological history, like those of the 

 -*■ human race, become more fragtnentary and illegible, 

 the farther back we trace them into the past. While the 

 younger rocks of the earth's crust have been made to yield 

 a more or less connected story of geographical and biolo- 

 gical evolution, the oldest rocks have till comparatively 

 lately been neglected, or have been tacitly left to mere 

 speculation and conjecture. Only within the last few 

 years have these ancient formations been seriously and 

 sedulously attacked by scientific methods of inquiry. 

 Though the progress of investigation has necessarily been 

 slow, a steady advance in knowledge can be chronicled. 

 There is a curious fascination in this department of 

 geology. These venerable rocks reveal to us the oldest 

 known part of the outer shell of our planet. The 

 palimpsest of the earth's surface has been written over 

 again and again during the long ages of geological history ; 

 but down among these bottom-rocks we reach the earhest 

 recognizable inscriptions, and come as near towards the 

 beginning of things as geological evidence by itself is 

 ever likely to lead us. These records carry us back to a 



'The Friday evening lecture delivered at the Royal Institution en June 7, 

 by Dr. Archibald Geikie, F.R.S. 



time anterior to that of the oldest fossiliferous formations, 

 possibly to an epoch that preceded the appearance of 

 vegetable or animal life on the globe. They reveal to us 

 the very foundations of the earth's crust, on which all 

 other know n rocks rest, and out of the waste of which the 

 greater part of these rocks has been formed. 



Within the last ten years, after prolonged misconception 

 and neglect, the most ancient rocks of the British Isles 

 have come to occupy a foremost place among the re- 

 searches of the geologists of this country. The tracts 

 where they are now exposed to view, often among the 

 wildest mountains, or " placed far amid the melancholy 

 main," have become favourite geological hunting-grounds, 

 and have furnished a notable amount of material for those 

 disputes and combats which seem to form a necessary 

 element in geological progress. Avoiding, as far as 

 possible, matters of controversy, I propose this evening 

 to offer a brief outline of the actual state of knowledge, 

 up to the present time, of the history of those ancient 

 crystalline masses of which our north-western mountains 

 ate composed.^ The storv is a somewhat involved and 

 complicated one. But its main points may perhaps be 

 conveniently grasped, if we bear in mind that they 

 naturally group themselves into four sections : (i) the 

 Archaean period ; (2) the Cambrian period ; (3) the 

 Lower Silurian period ; (4) the period of the younger 

 Schists. 



Let me at the outset remark that in the investigation of 

 these early ages of geological history we enjoy in this 

 country a special advantage. The British Isles stand on 

 the oceanic border of a great continental region. They are 

 therefore placed along that critical belt where not only 

 have terrestrial disturbances been especially numerous and 

 violent from the earliest geological times, but where an 

 oscillation upward or downward of a few hundred feet 

 has sufficed to make all the difference between land and 

 sea. In the heart of a continent, as, for example, over the 

 vast plains of Russia, long cycles of geological time have 

 passed without serious disturbance of any kind. To this 

 day some of the ancient PaUcozoic sediments in that 

 region, for hundreds of square miles in extent, lie as level 

 as when they were deposited on the sea-floor. They have 

 been uplifted bodily into land, but still remain little more 

 than mere hardened mud and sand. In Western Europe, 

 on the other hand, where from the remotest geological 

 antiquity the oscillations and dislocations have been in- 

 numerable, every successive continental uplift has recorded 

 itself in some crumbling or fracture of the rocks. Hence 

 in the geological map of that region the various forma- 

 tions form a pattern of exceeding complexity, while in the 

 maps of Eastern Europe each of them covers a broad 

 unbroken expanse. 



I. — The ArcJuean Period. 



The oldest known rocks of Europe, now generally 

 termed Archaean, are well exposed along the north- 

 western borders of the continental area from the extreme 

 north of Scandinavia, by the west coast of Scotland, to 

 Galway Bay in the west of Ireland, a total distance of 

 some 1600 miles. They give rise to topographical features 

 which, where fully developed, strongly distinguish them 

 from all younger formations. Nowhere else can such ex- 

 traordinary unevenness of surface be found. Knobs, 

 hummocks, and ridges of bare or almost bare rock, 

 separated by narrow gullies or by wider winding valleys, 

 roughen the ground in every direction. In the hollows 

 lie innumerable tarns and lakes, or flat tracts of bog 

 where lakes once were. In some districts, indeed, there 

 is as much water as land in a given number of square 

 miles. On a large scale, this type of scenery is perhaps 



' It would be obviously out of place to include here references to the 

 voluminous literature of the subject. A condensed summary will be found 

 in the Report by the officers of the Geological Survey, Quart. Joum. Geol. 

 Soc. vol. xliv., 1888. 



