118 



DISCOVERY 



approximate estimate of the yearly movement to be 

 expected. It would appear that in many places the 

 velocity of displacement must be too small to be 

 measurable astronomically in a reasonable time. How- 

 ever, in three or four places it should be possible to 

 establish the movement by measurements repeated 

 after a ten years' interval. In the case of the move- 

 ment of Greenland relatively to Europe, I. P. Koch 

 (the cartographer of the Danish Expedition of 1906-8) 

 has made a comparison between the observations of 

 this expedition and those of the second German North 

 Polar expedition of 1870 and still older observations 

 of Sabine in 1823. He has succeeded in deducing evi- 

 dence that the distance of Greenland from Europe has 

 noticeably increased in the interval, by an amount 

 exceeding considerably possible errors of observation. 

 There is evidence of a movement of about 15 metres a 

 year which is in complete agreement with that to be 

 expected from the displacement theorj'. 



We will conclude with this the series of examples from 

 our chain of evidence. If the standpoint of the dis- 

 placement theory be taken up, numerous problems 

 immediately present themselves, of which the most 

 important is perhaps the nature of the forces which 

 give rise to the displacements. Here no final conclu- 

 sion can be reached, but the problem has been so far 

 examined by the theoretical physicists and geophysi- 

 cists as to leave no doubt as to the possibility of such a 

 force existing. According to the displacement theory, 

 the continents display, in general, a movement towards 

 the West and towards the equator. Koppen ascribes 

 this latter tendency to the action of the force directed 

 away from the pole which tends to drive towards the 

 equator all floating bodies whose centres of gravity are 

 higher than their centres of buoyancy. This force 

 has been calculated to be of the magnitude of one three- 

 millionth of the weight of the body, and so to be rather 

 more than the tidal force. It may be shown that this 

 force is sufficiently great to pull the continental masses 

 through the underlying layers with the necessary slow- 

 ness, even if these la3'ers are as rigid as steel at ordinary 

 temperatures. On the other hand, it seems question- 

 able whether this force can explain the great Tertiary 

 mountain folds, which extend from the Himalayas 

 through the Alps to the Atlas Mountains, along the 

 line of the equator in those times. It is not impossible 

 that at that period, and perhaps in the earlier Carboni- 

 ferous period, still other forces existed in addition to 

 the normal force directed from the pole, owing to rapid 

 displacements of the pole and the consequent readjust- 

 ment of the hgure of the earth to the new polar axis, 

 these forces being perhaps twenty to a hundred times 

 as great. This would give a possible explanation of 

 the fact that this equatorial mountain folding is limited 

 to these periods. 



Just as the movement from the poles manifests itself 

 principally in mountain folds along the equator, so also 

 the westward movement of the continents is evidenced 

 by many strikingfeatures of the earth's face which 

 has hitherto been completely unexplained. We have 

 already instanced the frontal resistance which the 

 American continental masses experience in moving 

 through the ancient and deeply cooled bottom of the 

 Pacific, a resistance which has led to the throwing up 

 of the gigantic mountain chain of the Andes. Since 

 this frontal resistance must have a much greater 

 influence for small masses than for large, these small 

 masses will be left behind in the general westward 

 movement. Thence arises the great sweep of the 

 Antilles, left far to the east by America, and the great 

 bend of the so-called southern Antilles between Tierra 

 del Fuego and \\'est Antarctica. Thence also comes 

 the partial separation of the eastern edge of Asia in 

 the form of chains of islands, and the separation, long 

 ago completed, of the former Australian coastal chain 

 which now forms New Zealand. By the same move- 

 ment Ceylon has been broken away from India, and we 

 see evidence of it also in the bending of all the ends of 

 continents towards the east, such as the southern end 

 of Greenland, of Tierra del Fuego and the northern end 

 of Graham Land. Schweydar has suggested an origin 

 for the force driving the continents westward which 

 he believes to be due to the procession of the earth's 

 axis, but the whole question of the origin of the forces 

 is so much in a state of flux that it is impossible at 

 present to reach any final conclusions. 



New Light on Old 

 Authors 



IV. THE GOLDEN BRANCH 

 By R. S. Conway, Litt.D., F.B.A. 



Hulme Professor of Latin in tlie University of I\Iancbester 



Most of us who have any interest in primitive religion 

 and folk-lore know the name of Sir James Frazer's 

 great book. The Golden Bough. But it is quite likely 

 that a large number of those who have from time to 

 time quarried in its wonderful mines of learning, or 

 strayed in its charming avenues of fancy, would find 

 it hard to say just why he gave it that name. And 

 even if they did remember something about the 

 Vegetable-Spirit, they might still find it difficult to 

 know how it was connected with Vergil's story of the 

 descent of ^Eneas into the Underworld, and his having 

 to pluck a golden branch from the midst of a dark 

 forest in order to traverse that world unscathed. 

 And in truth their difficulty would be pardonable. 



