6o8 



NATURE 



\April 24, 1884 



|)o;ed in 1702 to the Royal Academy of France, that all stones, 

 fossils included, \i ere derived from liquid stone seeds, is gravely 

 considered and rejected. 



The description of volcanoes, both active and extinct, is also 

 given in a lucid manner ; bnt tlie opinions as to the cause of 

 vulcanicity are sometimes very peculiar, including the theory of 

 Dr. Lister — that they are originated by an inflammable mineral 

 called pyrites. 



The origin of basilt (basaltes) is correctly given, according 

 to the researches of Desmarest in Auvergne, and Raspe in 

 Germany, so that before Werner no erroneous views on that 

 suliject were held. 



Hut it is a most remarkable fact that there was not even an 

 attempt made to give an explanation of stratigraphical geology, 

 and how the different rocks \\ere formed, or to connect certain 

 sets of fossils with certain rocks in which they occur ; so that in 

 many respects we can claim that geology is a child of the last 

 hunilred years. 



Abraliam Gottlob Werner, the great teacher of the Freiberg 

 Academy of Mining, may be considered one of the founders of 

 modern geology. In 1785 he delivered the first course of 

 geognosy, as distinct from mineralogy, and by his great know- 

 ledge of all matters connected with the latter .science and minmg, 

 and his excellent method of teachiuL', he had an enormous 

 influence upon the advancement of geology. Therefore, as far 

 as I am aware, the word ge gnosy was first used two years after 

 the last volume of Chambers' " Cyclap;i;dia " appeared. 



A great retrograde step was, however, made by Werner when 

 be brought out his famous theory of the aqueous origin of basalt, 

 usually named the theory of Ncptunisni. After the war between 

 the Neptuiiists and the Plutonists (those who maintained the 

 igiieous origin of basalt) had been raging for some years, most 

 of the disciples of Werner — acting ai partisans, and instead of 

 trying to elucidate the truth, were only iient upon making liy all 

 means in their i-ower the cause advocated by them victorious — 

 for a time managed to get the upper hand. Those scientific 

 men, who knew froji their own experience that Werner's 

 doctrines on the subject were incorrect, preferred to retire 

 from the contest, and refused to fight with the same unfair 

 weapons. 



Of equal, if not of greater importance, are the labours of 

 Jaaies Hutton, who, in 1788, published his "Theory of the 

 Earth," in which, for the first time, the complicated structure of 

 the surface of the earth is explained by the agency of natural 

 forces, still at work at tte present day. With this the founda- 

 tion of modern geology was securely established, and though in 

 some respects the great Scotch 1 hilosopher v.ent too far, his 

 system was, nevertheles-, the only true one on which his succes- 

 sors could build that branch of knowledge now claiining a pro- 

 mi lent rank amon^jst its sisters as an inductive science. And 

 when William Smith, the modest English land surveyor, in 1790 

 published his "Tabular View of the Briti-h Strata," in which 

 the first attempt was made to connect certain fossils w ith certain 

 str.ata, an attempt turning out a masterpiece of patient research 

 and skill, a further great step was made in advance, and instead 

 of inerely theori in' on disconnected facts, the greater portion of 

 gejlogical students began to rely more upon the facts collected 

 by them and others, than upon speculative views, however 

 fascinating they might be. 



In entering upon a short review of the physics relating to the 

 great system of which our earth is only a very inconsiderable 

 speck, we find th.it although men of the highest scientific merit 

 hid tried to explain the origin and nature of the Cosjios, and the 

 laws by which it is governed, not one speculation had been 

 adopted at the time of the publication of the " Cyclopaedia" of 

 Chambers, as possessing all the necessary precision for the entire 

 satisf,action of inductive reasoning. 



It was only at the end of list century that Pierre Simon 

 Laplace published his two great works, " Exposition du Systeme 

 du Monde" in 1796, and "La Mecanique celeste" in 1799. 

 This cosmogony, usually called the " Nebular Hypothesis," has 

 hitherto stood the test of inquiry nearly a whole century ; all the 

 facts — and they are innumerable — tending invariably to testify at 

 least to the great probability of its general correctness. In 

 justice I ought here to mention that Immanuel Kant published 

 in 1755 his cosmical theories in his work " Allgemeine 

 Naturgeschichte und Theorie des Himmels," in which the gre.it 

 Konigsberg philosopher came to the same conclusions after- 

 wards so convincingly demonstrated by the French mathe- 

 matician. 



But when we leave the Cosmos and confine our.-elves to our 

 small planet, we find ourselves surrounded by such diflicuhies 

 that we appear just as far now from a true conception of the 

 constitution of the earth's interior as our predecessors were at 

 the beginning of this century. 



Numerous theories, based upon careful calculations, as to the 

 thickness of the crust of the earth have been advanced. Some 

 physicists give to our earth so thin a cru-t that it has been 

 compared to the rind of an orange, the fruit inclosed in it 

 repre.-enting the molten matter of the globe ; others affirm that 

 the crust is of much greater thickness, while there are some who 

 maintain that our planet has cooled so thoroughly that it n mw 

 forms a mass of rock of various density from the surface to the 

 very centre. Other theories (or, better stated, hypotheses) giving 

 to our globe a crust of more or less thickness, with a hard 

 metallic nucleus in tlie centre, and matter in a high state of 

 fusion filling the space between both, have been advocated by 

 other scientilic men, and mathematical proofs in support have 

 not been wanting. However, objections apparently fatal to 

 them all have been brought forward at one time or another by 

 physicists, astronomers, or geologists, according to their particu- 

 lar line of study, and we can therefore only wait patiently and 

 follow attentively the careful researches continued in all civilised 

 countries, applying at the same time every new discovery to the 

 elucidation of a problem, the more tantalising as its solution has 

 for many years appejred to be within our grasp. 



The great hopes that the deep borings lately obtained in 

 artesian wells, or careful temperature observations in deep 

 mines, would supply us with some material for advancing this 

 question, by offering important and reliable data of a uniform 

 ciraracter, have not been fulfilled. It appears, on the contrary, 

 from the deep borings at Sperenberg, in Germany, reaching 

 nearly to 4200 feet, that the increase of heat exhibits a remark- 

 able retardition of its rate the deeper we descend. And even 

 if we take convection and conductivity of the rocks into account, 

 there are scarcely two localities where the same ratio of increase 

 in the temperature has been observed, in some that ratio being 

 more than treble that of others. There may once have been a 

 uniform cooling of the original crust of the earth, now almost 

 entirely removed or remodelled, but there is no doubt that this 

 difference in the increase of temperature depends now either 

 up jn local generation of heat by hydro-chemical action or 

 mechanical agencies of enormous power still at work. Thus in 

 localising the variable increase of temperature, the vera causa 

 both for the crumpling and metamorphism of rocks, for the 

 formation of mountain chains, as well as for the origin of vol- 

 canic action, might be traced with more reliance than to seek to 

 establish a general law that most probably no longer existed 

 when Ihestrata acce sible to our examination were formed. 



Leaving the domini )n of theory and returning to the actual 

 work of the geologi-t in the field, 1 need scarcely say that the 

 task already accomplished h.is been truly gigantic. Patient re- 

 search in the civilised countries of f-urope, in the United States 

 of North America, and mo-t of the English colonies, as well as 

 the work of travellers to almost every part of the globe — of the 

 latter I wish only to allude to Baron von Richthofen's excellent 

 late researches in China — have made us acquainted with .such 

 remarkable and iimumerable data that it is impossible for any 

 man, however studious he may be, to gain more than an imper- 

 fect knowledge of the material already accumulated. 



The relations of the plutonic, metamorjihic, sediaientary, and 

 volcanic rocks to each other have been clearly defined, and most 

 valuable facts have been brought together, from which the past 

 history of our globe is being constructed, while the pala;ontolo- 

 giat has done his work equally well in classifying the wonderfully 

 complex animal and vegetable life, always in harmony with the 

 conditions i f the earth's surface, gradually and during untold 

 ages reaching, by evolution, the present stage of existence and 

 perfection. 



It would lead me too far to enter into a discussi:)n of all the 

 theories advanced as to the cause or causes by which mountain 

 chains and seas have been formed, and volcanoes and earth- 

 quakes — -because in mot instances the two latter are intimately 

 connected with each other — have been originated. Elie de Beau- 

 mont's theory of the sudden upheaval of parallel mountain 

 chains, first publi-hed in 1833, although at one time finding 

 great favour on the continent of Europe, was never adopted by 

 any geologist of note, the teachings of Hutton and Lyell leaving 

 j no room for the doctrines of the paroxysmal school. Moreover, 

 I when the size and direction of mountain chains were taken into 



