Sept. I, 1 88 1 ] 



NATURE 



419 



although the most perfect explanation of a chemical reaction 

 consists of a statement of the atomic interchange which takes 

 plice between tuo molecules ; or the change of mutual eom- 

 biaation between the atoms in one molecule. 



It lias, however, been proved tJiat tlie heat of combinatioa 

 affords a measure of its force ; and we know that in giving off 

 heat particles of matter undergo a diminution of velocity of 

 motion. We see, accordingly, that substances capable of exert- 

 ing great force by their combination are those which can undergo 

 a great diminution of the velocity of their internal motions, and 

 reciprocally. 



The force of chemical combination is evidently a function of 

 atomic motion. 



It has been shown that the relative velocities of certain atomic 

 interchanges afford a measure of the amount of chemical action 

 between two substances ; but a vast amount of work will doubt- 

 less be required to develop the atomic tlieory to the point of 

 explaining the force of chemical action in precise terms of atomic 

 motion. 



The general terms of chemistry are mere symbols. Each of 

 them serves to recall a group (usually a very large group) of facts 

 established by observation. The explanation of each term is 

 afforded by a careful study of the facts which it is used to 

 denote ; and, accordingly, a chain of evidence involving the 

 use of chemical terms can be fully understood only by chemists 

 accustomed to the consideration of such evidence. The general 

 outline of it may perhaps be to some general thinkers of suf- 

 ficient interest to attract them to further study of our science. 



SECTION C 



Opening Afideess by A. C. Ramsav, LL.D., F.R.S., &c., 



&c., Director-General of the Geological Survey, 



President of the Section 

 On the Origin and Progress of the Present State of British Geolo^, 

 Especially since the first Meeting of the British Association at 

 York in 1831 



In the year 1788 Hutton published his first sketch of his 

 " Theory of the Earth," afterwards extended and explained by 

 Playfair in a manner more popular and perspicuous than is done 

 in Hutton's own writings. In this grand work, Hutton clearly 

 explains that the oldest known strata, like their successors, are 

 derivative, and that as far as c/isci-jjt:on can discover, in all 

 geological time, "we find no ves'.ige of a beginning, and no tign 

 of an end." The complement to this far-seeing observation was 

 at length brought about by William Smith, in his original 

 "Geological Map of the Strata of England and Wales" in 

 1815, followed, in 1S16, by his "Strata Identified by Organised 

 Fossils." This great discovery, for such it was, threw a new 

 light on the history of the earth, proving what had before been 

 unknown, that all the " Secondary " formations, at least from the 

 Lias to the Chalk inclusive, contained each a set of distinctive 

 fossils by which it could be recognised. A law was thus pro- 

 vided for the identification of formations which geographically 

 are often widely separated from each oth-^r, not only in England 

 in the case of minor outliers, but also easily applicable to great 

 areas on the neighbouring continent of liurupe. 



In 181 1 the first volu ne of the Transactions of the Geo- 

 logical Society was published, and in 1826 27 there appeared 

 the first volume of the Proceedings, the object being to com- 

 municate to the Fellows as promptly as possible the Proceedings 

 of the Society " during the intervals between the appearance of 

 the several parts of the Transactions." The last volume of the 

 Transactions contiim memoirs read between the years 1 845- 1856, 

 and only four volumes of the Proceedings appeared between the 

 years 1826 and 1S45 inclusive, after which the title of the annual 

 volume was changed to that of the "Quarteily Journal of the 

 Geolo.^ical Society." The Geological Society, to which the 

 science owes so much, was therefore in full action when the 

 British Association was founded in 1831, and the memoirs read 

 before the Society from 1831 to this date may be said to show 

 generally the state of British geology during the last fifty years. 

 To this must be added the powerful influence of the first (1830) 

 and later editions of Lyell s "Principles of Geology," a work 

 which helped to lay the foundations of those researches in 

 Physical Geology which bjth in earlier and later years have 

 attracted so much attention. 



Fifty years ago, in this city, Viscount Milton was president of 

 the first meeting of " The British Associati-jn for the Advancement 

 of Science," which he explained had for its chitf object "to 

 give a stronger impulse and more systematic direction to scien- 

 tific inquiry." In his address he pointed out the numbers of 

 Philosophical Societies which had by degrees sprung up in all 

 parts of the kingdom ; and the practicability, through the 

 means of the Association, "including all the scientific strength 

 of Great Britain," " to point out the lines in which the direction 

 of science should move." 



In that year, 1831, Prof. Sedgwick was president of the Geo- 

 logical Society, and the Geological and Geographical Committee 

 of the Briiish Associati-^n recommended that geologists .should 

 examine the truth of that part of the theory of Elie de Beaumont, 

 in its application to England, Scotland, and Ireland, which 

 asserts that the lines of disturbance of the strata assii;)iable to the 

 same age are parallel ; that Prof. PhiUips be requested to draw 

 up a systematic catalogue of all the organised /bssils of Great 

 Britain and Ireland ; and that Mr. Robert Stephenson, civil 

 engineer, be reque-ted to prepare a report upon t/ie waste and 

 extension of the land on the east coast of Britain, and the tjucstion 

 of the permanence of the relative level of the sea and land. 



In 1881 it seems strange to us that, in 1831, with William 

 Smith's map of "The Strata of England and Wales, with pai-t 

 Scotland," before ihem, it should have been considered necessary 

 to institute an inquiry as to the truth of the general parallelism 

 of disturbed strata, which, in a limited area like Englind, had 

 suffered upheaval at different successive epochs ; and « e may 

 fancy the internal s liile with which Phillips, the nephew of 

 Smith, regarded the needless proposal. The masterpiece of the 

 old land-surveyor and civil engineer remains to this day the 

 foundation of all subsequent geol -gical maps of England and 

 Wales ; and as an nnaiiled c^ort of practical genius — for such it 

 was — it seems impossible that it should be surpassed, in spite of 

 all the accuracy and detail w hich happily modern science has 

 introduced into modern geological maps. 



The first paper read at York, in the year 1831, was by Prof. 

 Sedgwick, " On the Ger.eral Structure of the Lake Mountains of 

 the North of England." This was followed by "Supplementary 

 Observations on the Struclm-e of the Austrian and Bavarian 

 Alps," by the Secretary of the Society, Mr. Murchison, a 

 memoir at that time of the highest value, and still valuable 

 both in a stratigraphical point of view and also for the light 

 which it threw on the nature of the disturbances that originated 

 the Alpine u" juntains, and their relations in point of date to the 

 far more ancient mountains of Bohemia. In his elaborate 

 address in the same year, on his retiring from the president's 

 chair, he largely expatiates on the parallelism of many of the 

 great lines of disturbance of what were then distinguished as 

 the more ancient schistose and greywackc mountains, and quotes 

 the authority of Elie de Beaumont for the statement, "that 

 mountain chains elevated at the same period of time have a 

 general parallelism in the bearing of their component strata." 

 On a great scale this undoubtedly holds true, as, for example, 

 in the ca^e of the Scandinavian chain, and the more ancient 

 Pala;ozoic rocks north of Scotland, Cumberland, and even of 

 great part of Wales. The same holds good with regard to 

 the parallelism of the much more recent mou'tain ranges of the 

 Apennines, the Alps, the Caucasus, the Atlas, and the Hima- 

 layas, all of which strike more or less east and west, and are to 

 a great extent of post-Eccene, and even partly of post-Miocene 

 age. The same, however, is not precisely the cise with the 

 Apalachian chain and the Rocky Mountains of North America, 

 the first of which trends N.N.W., and the latter N.N.E. The 

 remarkable chain of the Ural Mountains trends nearly true 

 north and south, and is parallel to no other chain that I know 

 of, unless it be the Andes and the mountains of Japan. It is 

 worthy of notice that the chain of the Ural is of pre-Pcrmian 

 age according to Murchison, while Darwin has shown that the 

 chief upheaval of the Andes took place in post-Cretaceous 

 times. 



The Apalachian chain is chiefly of post-Carboniferous date, 

 and the Rocky Mountains have been re-disturbed and re-elevated 

 as late as ] ost Miocene times. 



In the same address Prof. Sedgwick entered an eloquent protest 

 against the broad uniformitarian views so powerfully advocated 

 in the first edition of Lyell's "Principles of Geology" in 1830, 

 in which, throw ing aside all discussion concerning cosmogony, 

 he took tlie world as he found it, and, agreeing with Hutton that 

 geology is in no way concerned with, and not sufficiently 



