io6 



NATURE 



iDcc. 5, 1878 



the memoir of Sir J. Hall {Trans. R. S. E., vol. vii. 1813), 

 and to that of the Petit Bomand in Savoy (Favre, 

 Recherches, pi. x.) ; at <5 is a valley open at one of its ends 

 and almost closed at the other ; at ^ is a vault almost 

 straight, the prolongation of which is very level ; at g, h, 

 and /are vaults twisted and a little broken, while at / is a 

 broken fold, the curves of which are almost vertical. All 

 these accidents of the ground recall those which have 

 been so often observed in the Jura, the Alps, and the 

 Appalachians. 



Fig. 2 represents a band of clay whose thickness was 

 about 40 mm. before compression, and 65 after. We 

 remark contortions similar to those of the preceding 

 figure, among others a vault a, very exactly formed. At 

 distances are seen vertical slices, on which the pressure 

 appears to have acted in a particularly energetic fashion, 

 and which maybe called "zones de refoulement ; " the 

 strata are there broken in an exceptional manner, often 

 separated from each other. One of these vaults is re- 

 placed by a single fault on the opposite side of the band 

 of clay. 



Before compression, in the band of clay in Fig. 3, were 

 seen the two divisions which are seen there now — that in 

 the right was 33 cm. long, and 25 mm. thick at a, and 35 

 at bj the left division was 25 cm. long, and 65 mm. thick. 

 A gentle slope united the part c to the part d. After 

 compression, the mean height of ab was 45, and that of c 

 75 mm. All the layers were spread horizontally. 



In this experiment I have sought to imitate the effect 

 of crushing at the limit of a mountain and a plain. The 

 height of the mountain c has been notably increased, the 

 five or six upper layers have advanced on the side of the 

 plain ; they encroach on it. The plain has, however, 

 offered a resistance sufficiently great to cause the strata 

 of the mountain to be strongly inflected at the bottom. 

 From this struggle between the plain and the mountain, 

 there resulted a cushion, d, which is the first hill at the 

 foot of the height. It also resulted that the strata of the 

 plain assumed an appearance of depression at contact 

 with the mountain in consequence of the vault which is 

 formed at b; they plunge underneath the mountain. 

 This resembles what is often seen in the Alps at the 

 junction of the first calcareous chain and the hills of 

 *'mollasse;" in fact, the strata of the latter rock seem 

 to plunge under those of the neighbouring heights. In 

 consequence of the pressure, there are formed several 

 ranges of hills in the plain between b and a. 



" In Fig. 4 the band of clay had, before compression, a 

 thickness of 45 mm. ; after that the culminating point was 

 more than 10 cm. I have here sought to represent what 

 must happen when terrestrial pressure is exerted on hori- 

 zontal strata still moist, deposited at the bottom of a sea 

 where are two mountains already solidified. For this 

 purpose I placed in the caoutchouc and under the clay 

 two bare cylinders of wood, a and b, of [about 35 mm. 

 radius, at 20 cm. from the ends of the band of clay, and 

 at the same distance from each other. Before compres- 

 sion, the surface of the clay and the strata were com- 

 pletely horizontal. Pressure gave rise at the top of the 

 half-cylinder, a, to a valley, c, formed by a twisting of 

 the beds to the right, and by a little mountain, d, to the 

 left. But I do not believe that it has ever been thought 

 to assign to a valley an origin of this nature. 



" On the other semi-cylinder, b, is produced an enormous 

 elevation which has carried the ground to e, with such a 

 rupture that the left lip, /,g, has suffered a complete 

 reversal by turning, as on a hinge, around the horizontal 

 line which passes by the point h. It follows that the 

 four upper strata of clay designated by the figures i, 2, 3, 4, 

 being in a normal position before compression, are, after 

 that, so arranged as to show the succession represented 

 by the following arrangement of figures : — i, 2, 3, 4, 4, 3, 

 2> i> i> 2, 3, 4, making the section of this formation by 

 a line drawn from x to z. li the left lip should disappear 



vye should then have between the points x and z the sec- 

 tion I, 2, 3, 4, 5, I, 2, 3, 4, 5. Sections analogous to 

 these, presenting inversions in the order of strata, are 

 known to geologists. 



" The forms assumed by the clay depend on several cir- 

 cumstances which it is difficult to describe, such as the 

 strength and the rate of compression, the thickness and 

 the greater or less plasticity of the clay, &c. Why have 

 accidents of the upper surface of the clay, which are inti- 

 mately connected with those of the interior of the mass, 

 so small an extension that they are not even similar in 

 the two sides of a band of clay ? This small continuity 

 is owing to causes which we can neither foresee nor 

 appreciate. Is it not the same in nature ? Why is the chain 

 of the Alps not a true chain, but a succession of masses 

 often oblique with respect to each other ? Why, in the 

 Jura, do we see chains which have for their prolongation 

 plains and valleys ? It is always the case that the forms 

 and structures obtained in these experiments have an 

 incredible resemblance to those which are found on the 

 surface of the globe. But it must be admitted that many 

 of the latter have not been reproduced by these artificial 

 crushings. 



"It appears probable that, by pressures more powerful 

 and more variedly employed, we might obtain again 

 very different structures. But I have not thought it 

 necessary to multiply these experiments, thinking that 

 the varied forms which have resulted show sufficiently 

 the effects of crushing." 



GEORGE HENRY LEWES 



T^HIS is a name which has been long before the 

 -*- reading public of England, and the announcement 

 of Mr. Lewes' s death, on Saturday last, at the age of 

 sixty-one years, will be received by very many with 

 genuine regret.* This will be especially the case with those 

 who have reached or passed middle life, for latterly Mr. 

 Lewes's name has come little before the public, and what 

 work he has done appeals to a comparatively small circle. 

 Of Mr. Lewes's many-sidedness every one knows ; he com- 

 menced his career as a novelist, and ended as a physio- 

 logical psychologist — perhaps in some respects no very 

 great leap, after all ; indeed the two functions may be 

 said to be combined in that greatest of philosophical 

 novelists, if not of novelists absolutely, " George Eliot," 

 Mr. Lewes's widow. Science owes a good deal to Mr. 

 Lewes ; for, though he made little or no pretension to 

 be an original investigator in physical science, he did 

 very much by his writings to give the general public an 

 idea of what real science is, and to help forward 

 the good work of carrying it into every-day life. 

 His "Physiology of Common Life" had a long and 

 deserved popularity, and even yet, we believe, is 

 often "asked for" at libraries and book-shops. His 

 "Biographical History of Philosophy" is thoroughly 

 readable and full of information, which is more than can 

 be said of philosophical works generally. Of his " Life 

 of Goethe," one of the very few masterly biographies, we 

 leave it to others to speak, though he did much there to 

 bring out the real importance of Goethe's botanical and 

 other scientific researches. Of his latest work, " Problems 

 of Life and Mind," we spoke at length on the appearance 

 of the volumes that have been published ; in these 

 volumes and in one or two letters and articles contributed 

 to our pages, Mr. Lewes was perhaps at his best as an 

 investigator in a department of science with which 

 we are cautious of interfering, but which has a strange 

 fascination for many thinkers. Altogether Mr. Lewes 

 filled an important and many-sided place in the intel- 

 lectual life of this country during his long career. 

 It is easy to say that a man of his unusual keen- 

 ness of mind might have achieved jjermanent great- 

 ness by concentrating his great store of energy in one 



