454 



NATURE 



[September 4, 1890 



To this letter, reflecting so gravely on his honour and integrity, 

 Lavoisier made no reply. Nor did Laplace, Le Roi, Vander- 

 monde, or any one of the Academicians concerned, vouchsafe 

 any explanation. De non apparentibus et de non existentibus 

 £adem est ratio. No explanation appeared, because none was 

 possible. M. Berthelot ignores this letter, which is the more re- 

 markable, since reference is made to it in more than one of the 

 publications which he tells us he has consulted in the prepara- 

 tion of his account of the Water Controversy. If he knew of 

 it he must regard it either as unworthy of an answer or as 

 unanswerable. 



It would be heaping Ossa on Pelion to adduce further evidence 

 from letters of the time of what Lavoisier's contemporaries 

 thought of his claims. De mortuis nil nisi bonum. I would 

 much more willingly have dwelt upon the virtues of Lavoisier, 

 and have let his faults lie gently on him ; but I have felt it in- 

 cumbent on ine on this occasion to make some public answer to 

 M. Berthelot's book, and in no place could that answer be more 

 fittingly given than in this town, which saw the dawn of that 

 work out of which these grand discoveries arose. It may be 

 that much of what I have had to say is as a twice-told tale to many 

 of you. I trust I need make no apology on that account. The 

 honour of our ancestors is in our keeping, and we should be 

 unworthy of our heritage and false to our trust if we were slow 

 to resent or slack to repel any attempt to rob them of that 

 glory which is their just right and our proud boast. 



SECTION C. 



Opening Address by A. H. Green, M.A,, F.R.S., Pro- 

 fessor OF Geology in the University of Oxford, 

 President of the Section. 



The truth must be told ; and this obliges me to confess that 

 my contributions to our stock of geological knowledge, never 

 very numerous, have of late years been conspicuously few, and 

 so I have nothing to bring before the Geelogical Section that 

 can lay any claim to be the result of original research. 



In fact, nearly all my time during the last fifteen years has 

 been taken up in teaching. This had led me to think a good 

 deal about the value of geology as an educational instrument, 

 and how its study compares with that of other branches of learn- 

 ing in its capability of giving sinew and fibre to the mind, and 

 I have to ask you to listen to an exposition of the notions that 

 have for a long time been taking shape bit by bit in my mind on 

 this subject. 



I am not going to enter into the question, handled repeatedly 

 and by this time pretty well threshed out, of the relative value 

 of natural science, literature, and mathematics, as a means of 

 educational discipline ; for no one who is lucky enough to know 

 a little of all three will deny that each has an importance of its 

 own, and its own special place in a full and perfect curriculum. 

 The question which is the most valuable of the three I decline 

 to entertain, on the broad general ground that "comparisons 

 are odorous," and for the special reason that the answer must 

 depend on the constitution of the mind that is to be disciplined. 

 I might quite as reasonably attempt to lay down that a certain 

 x3iet which suits my constitution and mode of life must agree 

 equally well with all that hear me. 



I need scarcely say that nothing would induce me, if it could 

 possibly be helped, to say one word that might tend to disparage 

 the pursuit to which we are all so deeply attached. But I can- 

 not shut my eyes to the fact that, when geology is to be used as 

 a means of education, there are certain attendant risks that need 

 to be carefully and watchfully guarded against. 



Geologists, and I do not pretend myself to be any better than 

 the rest of them, are in danger continually of becoming loose 

 reasoners. I have often had occasion to feel this, and I recall a 

 scene which brought it home to me most forcibly. At-a gathering, 

 where several of our best English geologists were present, the 

 question of the cause of changes of climate was under discussion. 

 The explanation which found most favour was a change of the 

 position of the axis of rotation within the earth itself ; and this, 

 it was suggested, might have been brought about by the up- 

 heaval of great bodies of continental and mountainous land 

 where none now exist, and an accompanying depression of the 

 existing continents or parts of them. That such a redistribution 

 of the heavier material of the ear h would result in some shifting 

 of the axis of rotation admits of no doubt. The important 



NO. 1088, VOL. 42] 



question is, How much? What degree of rearrangement of 

 land and sea would be needed to produce a shift of the amount 

 required ? It is purely a question of figures, and the necessary 

 calculations can be made only by a mathematician. I ventured 

 to suggest that some one who could work out the sum should be 

 consulted before a final decision was arrived at, for I knew per- 

 fectly well that not one of the company present could do it. 

 But if I say that my advice met with scant approval, I should 

 represent very inadequately the lack of support I met with. 

 The bulk of those present seemed quite content with the vague 

 feeling that the thing could be done in the way suggested, and 

 there was a general air of indifference as to whether the hypo- 

 thesis would stand the test of numerical verification or not. 



I could bring many other similar instances which seem to me 

 to justify the charge I have ventured to make ; but it will be 

 more useful to inquire what it is that has led to a failing, which, 

 if it really exist, must be a source of regret to the whole brother- 

 hood of hammerers. 



The reason, I think, is not far to seek. The imperfection of the 

 Geological Record is a phrase as true as it is hackneyed. No more 

 striking instance of its correctness can be found than that fur- 

 nished by the well-known mammalian jaws from the Stonesfield 

 slate. The first of these was unearthed about 1764 ; others, to 

 the number of some nine, between then and 1818. The rock in 

 which these precious relics of the beginning of mammalian life 

 occur has been quarried without intermission ever since ; it has 

 been ransacked by geologists and collectors without number ; 

 many of the quarrymen know a jaw when they see it, and are 

 keenly alive to the market value of a specimen ; but not one of 

 these prized and eagerly-sought-after fossils has turned up during 

 the last seventy years. 



Then, again, how many of the geological facts which we 

 gather from observation admit of diverse explanation. Take the 

 case of Eozoon Canadense. Here we have structures which some 

 of the highest authorities on the Foraminifera assure us are the 

 remains of an organism belonging to that order ; other naturalists, 

 equally entitled to a hearing, will have it that these structures 

 are purely mineral aggregates simulating organic forms. And 

 hereby hangs the question whether the limestones in which the 

 problematical fossil occurs are organic, or formed in some other 

 and perhaps scarcely explicable way. 



And this after all is only one of the countless uncertainties 

 that crowd the vvhole subject of invertebrate palaeontology. In 

 what a feeble light have we constantly to grope our way when 

 we attempt the naming of fossil Conchifers for instance. The 

 two species Gryphcea dilatata and G. bilobata furnish an illustra- 

 tion. Marked forms are clearly separable, but it is easy to 

 obtain a suite of specimens, even ftom the Callovian of which 

 the second species is said to be specially characteristic, showing 

 a gradual passage from one form into the other. And over and 

 over again the distinctions relied upon for the discrimination of 

 species must be pronounced far-fetched and shadowy, and are, 

 it is to be feared, often based upon points which are of slender 

 value for classificatory purposes. In the case of fossil plants the 

 last statement is notoriously true, and yet we are continually 

 supplied with long lists of species which every botanist knows 

 to be words and nothing more, and zonal divisions are based 

 upon these bogus species and conclusions drawn from them. 



It is from data such as have been instanced, scrappy to the 

 last degree, or from facts capable of being interpreted in more 

 than one way, or from determinations shrouded in mist and 

 obscurity, that we geologists have in a large number of cases 

 to draw our conclusions. Inferences based on such incomplete 

 and shaky foundations must necessarily be very largely hypo- 

 thetical. That this is the character of a great portion of the 

 conclusions of geology we are all ready enough to allow with our 

 tongue — nay, even to lay stress upon the fact with penned or 

 spoken emphasis. But it is open to question whether this 

 homage at the shrine of logic is in many cases anything better 

 than lip-service ; whether we take sufficiently to heart the 

 meaning of our protestations, and are always as alive as our 

 words would imply to the real nature of our inferences. 



A novice in trade, scrupulously honest, even morbidly con- 

 scientious to begin with, if he lives among those who habitually 

 use false scales, runs imminent risk of having his sense of 

 integrity unconsciously blunted and his moral standard insen- 

 sibly lowered. A similar danger besets the man whose life is 

 occupied in deducing tentative results from imperfectly ascer- 

 tained facts. The living, day by day, face to face with approxi- 

 mation and conjecture must tend to breed an indifference to 



