2l8 



SCIENTIFIC NEWS. 



[Sept. 7, 1888. 



I mention this particularly, as those names thus 

 painted have subsequently acquired an historical scien- 

 tific interest. In 1844 the block split into two 

 pieces, and since that the frost has rent it into 

 a mere heap of debris. Forty years after the first 

 rupture — i.e., in 1884 — M. Forel was able to identify this 

 heap by the vestiges of the paint-pot still remaining on 

 some of the fragments. 



It had then travelled a distance of 2,400 metres 

 (7,874 feet) from its position in 1840, showing that this 

 great mass of ice on which it rested had been flowing down 

 the valley at a mean rate of 1 79 feet per annum, a slower 

 speed than usual, owing to the fact that the downward 

 incline of this glacier is very small, so small that it ap- 

 pears in most parts nearly level. 



This movement of glaciers is the most important ele- 

 ment of the whole subject in reference to their work in 

 the sculpture of the earth, and this medial moraine of 

 the Aar Glacier is classic ground in reference to it, as it 

 was here in the early days of glacier research that a very 

 striking and demonstrative discovery was made. Agassiz 

 knew that in 1827 Hugi had built a sort of refuge or 

 shelter on the moraine, and also knew particulars con- 

 cerning its position. In 1839 Agassiz, with some com- 

 panions, trying to find some traces of it, spent four hours 

 in the search, and were returning, when suddenly they 

 came upon a solidly-built hut, but could not believe that 

 it was Hugi's, which they knew was at the confluence of 

 the Finsteraar and Lauteraar Glaciers, close to the 1m 

 Abschwung promontory of rock, from which they were 

 now at a considerable distance. The hut was in 

 good condition, even some of the hay and straw remain- 

 ing on the roof. They examined the inside, and there 

 found a bottle containing papers. One was in Hugi's 

 handwriting, stating that he had revisited the hut in 

 1830, and found that it had moved about 100 paces from 

 its original position. A second paper described a third 

 visit- in 1836, when he found that it had travelled 2,200 

 feet from the rock against which he built it. A third 

 paper stated that some naturalists from Berne and Basle 

 had at about this time repaired the hut and used it as a 

 shelter while weather-bound in attempting to cross the 

 glacier to Grindelwald. 



Agassiz measured the distance from the original place 

 and found that it then amounted to 4,400 feet, and there- 

 fore the hut had travelled in the three years between 1836 

 and 1839 as far as in the nine years from 1827 to 1836. 

 Another measurement, in 1840, showed a progress of 200 

 feet in the year. These measurements he recorded in 

 the visitors' book of the Grimsel Hospice, with an appeal 

 to future visitors to continue the investigation. 



Making due allowance for Hugi's rough measurements 

 by stepping, a remarkable acceleration is here apparent, 

 and is explained by subsequent observations, which show 

 that the middle of the glacier, like the middle of a river, 

 flows more rapidly than its sides. Hugi's hut was at 

 first at the spot where the right and left banks of the 

 confluent glaciers meet, but as it advanced it came out 

 into mid-stream, and its pace was accelerated accordingly. 

 The maximum thickness of the ice was reached at about 

 1836. This diminished downwards by combined 

 action of sun-heat on the upper surface and earth-heat 

 and friction below. 



Other curious results of " ablation," or thinning down, 

 of glaciers are peculiarly well shown on the Aar Glacier, 

 and we examined them under expert guidance. I will 

 describe them in my next. 



ANCIENT OPINIONS AND PRE-SCIEN" 

 TIFIC FANCIES CONCERNING THE 

 INTERIOR OF THE EARTH. 



MANY ages before the rise of geology, the human 

 imagination had set itself to work, and philo- 

 sophers, basing upon some notions more or less vague 

 gleaned here and there, or setting out with the observa- 

 tion of a few local phenomena, had forged systems more 

 bold and ingenious than probable or logical, with the 

 object of explaining the structure of the earth's core. 

 Subsequently these old paradoxes were forgotten in 

 proportion as more serious hypotheses cropped up. Still 

 in the year 1678 savants were far from being agreed 

 on this mysterious question, and the margin left for 

 dreamers was still ample. 



Aristoteles proved, or believed that he had proved by 

 means of a syllogism, which has remained famous as a 

 specimen of a vicious circle, that the centre of the earth 

 coincided with the centre of the visible universe. Indeed 

 if we adopt the old astronomical notions, it would be 

 difficult to admit that the pivot of the heavens was placed 

 eccentrically with reference to the celestial sphere. 

 Almost all imaginable suppositions were put forward in 

 antiquity and in modern times when it was required to 

 conceive the physical condition of the earth's interior. 

 The bowels of the earth, according to Pythagoras, Em- 

 pedocles, and Plato, are on fire. 



Their opinion, maintained afterwards with more autho- 

 rity by Descartes and Leibnitz, still prevails in France, 

 strenuously advocated by such eminent champions as 

 Daubree, Faye, and De Lapparent. On the contrary, 

 according to Anaxagoras and Democritus, followed long 

 afterwards by Woodward, we walk upon a sphere filled 

 with water, encased in a thin coating of earth, like the 

 shell of an egg. Buffon avowed his ignorance, but he 

 did not favour the central fire. We do not know who 

 first gave us a nucleus of iron. Could he return to the 

 earth he might perceive with satisfaction that his view, 

 far from being forgotten is still sustained, among others, 

 by Professor Nordenskiold. Even the very existence ot 

 terrestrial magnetism constitutes a strong argument. A 

 certain number of more mystical thinkers supposed 

 beneath our feet a vast void in which there circulated a 

 sun, a moon, and planets, inhabited by plants, animals, 

 and rational beings of a very special nature. Others 

 affirmed that the world is perforated by a long tunnel, 

 opening at the two poles. Less daring speculators 

 were content to imagine the existence of great internal 

 seas, communicating with the superficial oceans. 



A very minute description of the earth's interior is 

 given by the celebrated Father Athanasius Kircher in a 

 work in two folio volumes, entitled Mundus Subterra- 

 neus. The treatise of this learned Jesuit merits the name 

 of an encyclopaedia, for we find here condensed the 

 principles or the applications of all the sciences which 

 are closely or remotely conneeted with the main ques- 

 tion : geography, astronomy, mechanics, physics, che- 

 mistry, and natural history. 



The subjoined figure which we borrow from La Nature 

 is taken from an engraving in Kircher's great work, 

 published in 1678. It is an ideal section of the earth, 

 showing the central fire, A, and the internal circula- 

 tion of the waters. 



Kircher's fundamental idea is a parallelism between 

 the human body or microcosm and the earth, geocosm. 



The inmost nucleus of the latter is in a state of igni- 

 tion, but the constitution of the mean and higher strata 



