160 



POPULAR SCIENCE NEWS. 



[November, 1888. 



upon a rose-bush ; but the magical change of 

 color can be made equally well upon a piece 

 of cloth, paper, or even the hand, and will 

 invariably cause much surprise and wonder- 

 ment. 



THE MEGALITHIC MONUMENTS 

 CARNAC. 



OF 



In the French province of Brittany there 

 still exist many relics of that strange prehis- 

 toric race which was so widely scattered over 

 the world, if we maj' assume that monuments 

 of similar form and construction indicate a 

 similarity of race, and not, as seems more 

 reasonable, to attribute the resemblance of 

 these simple structures to the natural develop- 

 ment of the human mind in widely separated 



countries, and in 



races not ethnologi- 

 callj' connected. 



These prehistoric 

 monuments occur 

 abundantly in 

 Western Europe 

 and Great Britain. 

 The celebrated 

 "Druids' Temple" 

 of Stonehenge is 

 one of the best-pre- 

 served, although it 

 is not likely that 

 tlie Druids had any 

 thing at all to do 

 with its construc- 

 tion. Little or 

 nothing is really 

 known about these 

 structures, and the 

 time and purpose 

 of their erection, 



and the race of men who built them, are still 

 an unsolved mystery. 



These monuments vary in size from single 

 stones, or groups of two or three, to such enor- 

 mous collections of stones as are found at 

 Carnac in Brittany, a view of which is given 

 in the accompanying engraving, copied from a 

 photograph. At present there are about five 

 hundred stones, regularly arranged to form 

 enclosures and roads. In the sixteenth cen- 

 tury it is said that ten or fifteen thousand 

 stones were visible, extending over six miles of 

 country ; but in the course of time the land 

 has been brought under cultivation, and the 

 stones have been removed or destroyed by the 

 inhabitants. This vandalism continued until 

 the past year, when the French government 

 appropriated the land for the purpose of per- 

 petually preserving this invaluable relic of 

 prehistoric times. 



It seems evident that these immense works 

 could be of no practical use to their builders, 

 and it is highly probable that they were either 

 erected as memorials of departed heroes and 

 important events, or else as temples for use in 

 connection with their religious rites and super- 

 stitions. Whatever the motive that led to 

 their erection, it must have been a powerful 

 one, as the amount of work indicated by such 



structures as Carnac or Stonehenge must 

 have been immensely great, especially to such 

 savage or semi-civilized people as we conceive 

 the men of early times to have been. It is 

 useless to speculate, however, upon their con- 

 dition or the extent of their civilization until 

 we have more actual information. In the case 

 of Stonehenge, its builders must have had 

 some astronomical knowledge, for it is so laid 

 out, that, at the time of the summer solstice, 

 the rays of the rising sun fall exactly upon 

 the central " altar-stone,'- casting thereon the 

 shadow of a large upright stone placed before 

 the door. This certainly indicates a condition 

 above that of actual barbarism. As these 

 ancient builders toiled at their arduous task, 

 they doubtless thought that the fame and his- 



tory of their work would last as long as the 

 earth itself; but a few hundreds or thousands 

 of years only have since passed, and not a 

 single fact in connection with them remains 

 known. Who can say whether a similar fate 

 maj' not befall the more extensive works of 

 modern times, and that in a few thousand 

 j'ears their immense ruins may be onlj' an 

 object of curiosity and sjieculation to the 

 people then living on the earth ? 



[Original in The Popular Science News.'[ 



THE TENDENCY OF MATTER AT THE 

 SURFACE OF THE EARTH. 



BV W. A. ASHE, F.R.A.S. 

 [Cunduded.'] 

 It is evident, that, if on the surface of such a solid 

 there is a film of matter more responsive to the mov- 

 ing force than our solid's arrested particles, it will 

 proceed towards the equator and the solid of equi- 

 librium, beyond symmetrical arrangement about 

 the more immovable portions of the figure. It 

 seems evident, therefore, that the most natural 

 conclusion for us to draw from the visible evidence 

 presented by a rotating oblate spheroid, is, that its 

 present outline is a natural result of the forces that 

 are acting on it; from which there are but two 

 further concliisious to be drawn, — one, that the 

 solid has attaiaed equilibrium, in which the diiler- 

 ent media composing it are arranged symmetrically 



about it in the approximate order of their specific 

 gravities, and that they have no tendency to further 

 movement ; the other, that the motion of the parti- 

 cles towards the above condition and arrangement 

 was arrested before either had been reached, and 

 that, as a result of the order of arrestation, de- 

 pending as it did on the nature of the several 

 media, there has resulted a solid of unsymmetri- 

 cal arrangement of such sort, that those which were 

 first arrested in their motion equatorwards would 

 be more nearly spherical than those latter; and 

 that, while the condition and position of the first 

 would prevent the latter reaching the outline of the 

 solid of equilibrium, it would be more near it than 

 in the case of those first arrested; so that, if we ac- 

 cept the earth as being an illustration of what we 

 wish to maintain, we should find the spheroid con- 

 taining the solids less oblate than that containing 

 the liquids, whilst that of the atmosphere should 



be the most oblate of 

 all, or have the great- 

 est difference between 

 the polar and equato- 

 rial diameters. We 

 have, therefore, to 

 conclude that, instead 

 of there being any 

 tendency, on the part 

 of the waters of the 

 earth, to form " two 

 vast polar oceans," 

 or of the atmosphere, 

 or of the correspond- 

 ing elements of any 

 other member of the 

 solar system, there is 

 either symmetrical 

 arrangement, because 

 of the solid of equi- 

 librium having been 

 attained, or, failing 

 this, that the ten- 

 dency on the part of 

 these aqueous, at- 

 mospheric, or other 

 elements is to accumulate about the equator. 



The full consideration of the question is affected 

 by the possibility of the momentum of the particles, 

 in moving from the sphere into the spheroid, car- 

 rying them beyond their position of equilibrium, — 

 a possibility that might result in the spheroid being 

 over-developed when its particles were at last 

 brought to rest, — a possibility, however, without a 

 great amount of probability in it; for it does not 

 seem possible to suppose that during the earlier 

 phases of existence of the members of our system, 

 a phase in which rotational velocity was undoubt- 

 edly increasing whilst the transferrence of the 

 particles towards the equator was being effected, 

 and at the same time radiation and consequent 

 gradual solidification — resulting in a lessening 

 ability amongst the particles to respond to the 

 translating force — are simultaneously proceeding, 

 could by any possibility result in an over-developed 

 solid : we may, therefore, proceed to the considera- 

 tion of other reasons that might be held as suffi- 

 cient to account for this assumed tendency. 



The most plausible reason that could be advanced 

 would be the assumption that the diurnal motion 

 is decreased and decreasing from its maximum 

 value, — an assumption that is entirely unsupported 

 by the evidence, which, on the other hand, almost 

 conclusively proves that our diurnal motion has a 

 fixed or so slightly altering value, that the most 

 careful measures of it, which the most precise of 

 astronomical methods permit of, point to its un- 

 varying nature; so that although there is no evi- 

 dence of there not being a change in its value of 



