Scientific Essays and Lectures

Then rose a very clever guess.  They must have been carried by icebergs, as much silt and stones (we know) has been carried, and have dropped, like them, to the bottom, when the icebergs melted.

There is great reason in that; but we have cause now to be certain that they did not come from Wales.  That they are not pieces of a rock older than the chalk, but much younger; that they were very probably formed close to where they now lie.

Now—how do we know that?

If you are not tired with all this close reasoning, I will tell you.—If you are, say so: but as I said at first, I want to show you what steady and sharp head-work this same geology requires, even in the nearest gravel-pit.

Well, then.  I do not think our gravel-pit will tell us what we want: but I know one which will.

You have all heard of Lady Grenville’s lovely place, Dropmore, beyond Maidenhead; where the taste of that good and great man, the late Lord Grenville, converted into a paradise of landscape-gardening art a barren common, full of clay and gravel-pits.  Lord Grenville wanted stones for rockwork; in those pits he found some blocks, of the same substance as those of Stonehenge or Pirbright.  And they contain the answer.  The upper surface of most of them is the usual clear sugar-sandstone: but the under surface of many has round pebbles imbedded in it, looking just like plums in a pudding; the smaller above and the larger below, as if they had sunk slowly through the fluid sand, before the whole mass froze, as it were, suddenly together.  And these pebbles are nothing else than rolled chalk flints.

That settles the matter.  The pebbles could not come from Wales; there are no flints there.  They could not have been made before the chalk; for out of the chalk they came; and the only explanation which is left to us, I believe, is, that over the tops of the chalk downs; over our heads where we stand now, there once stretched layers of sand and gravel, “Tertiary strata” as I have been calling them to you; and among them layers of this same hard sandstone.

When the floods came they must have swept away all these soft sands and gravels (possibly to make the Bagshot sands, of which I shall speak presently), and left the chalk downs bare; but while they had strength to move the finer particles, they had not generally strength to move these sandstone blocks, but let them drop through, and remain upon the freshly-bared floor of chalk, as the only relics of a tertiary land long since swept away; while some were carried off, possibly by icebergs, as far as Pirbright, and dropped, as the icebergs melted, both there, at Dogmersfield, and also, though few and small, in Eversley and the neighbourhood.

But how came these tertiary sandstones to be so very hard, while the strata around them are so soft?

Ladies and gentlemen, I know no more than you.  Experience seems to say that stone will not harden into that sugary crystalline state, save under the influence of great heat: but I do not know how the heat should have got to that layer in particular.  Possibly there may have been eruptions of steam, of boiling water holding silex (flint) in solution—a very rare occurrence: but something similar is still going on in the famous Geysers or boiling springs of Iceland.  However, I have no proof that this was the cause.  I suppose we shall find out some day how it happened; for we must never despair of finding out anything which depends on facts.

Part of the town of Odiham, and of North Warnborough, stands, I believe, upon these lower beds, which are called by geologists the Woolwich and Reading beds, and the Plastic clays, from the good brick earth which is so often found among them.  But as soon as you get to Hook Common, and to Dogmersfield Park, you enter on a fresh deposit; the great bed of the London clay.

I give you a rough section, from a deep well at Dogmersfield House; from which you may see how steeply the chalk dips down here under the clay, so that Odiham stands, as it were, on the chalk beach of the clay sea.

In boring that well there were pierced:

Forty feet of the upper sands (the Bagshot sands), of which I shall speak presently.

Three hundred and thirty feet of London clay.

Then about forty feet of mottled clays and sands.

Whether the chalk was then reached, I do not know.  It must have been close below.  But these mottled clays and sands abound in water (being indeed the layer which supplies the great breweries in London, and those soda-water bottles on dumb-waiters which squirt in Trafalgar Square); and (I suppose) the water being reached, the boring ceased.

Now, this great bed of London clay, even more than the sands below it, deserves the title of a new creation.

As a proof—some of you may recollect, when the South-Western Railway was in making, seeing shells—some of them large and handsome ones—Nautili, taken out of the London clay cutting near Winchfield.

Nautili similar to them (but not the same) are now only found in the hottest parts of the Indian seas; and what is more, not one of those shells is the same as the shells you find in the chalk.  Throughout this great bed of London clay, the shells, the remains of plants and animals, are altogether a new creation.  If you look carefully at the London clay shells, you will be struck with their general likeness to fresh East Indian shells; and rightly so.  They do approach our modern live shells in form, far more than any which preceded them; and indeed, a few of the London clay shells exist still in foreign seas; in the beds, again, above the clay, you will meet with still more species which are yet alive; while in the chalk, and below the chalk, you never meet, I believe, with a single recent shell.  It is for this reason that the London clay is said to be Eocene, that is, the dawn of the new creation.

The chalk, I told you, seems to have been deposited at the bottom of a still and deep ocean.  But the London clay, we shall find, was deposited in a comparatively shallow sea, least in depth toward High Clere on the west, and deepening towards London and the mouth of the Thames.

For not only is the clay deeper as you travel eastward, but—and this is a matter to which geologists attach great importance—the character of the shells differs in different parts of the clay.

You must know that certain sorts of shells live in deep water, and certain in shallow.  You may prove this to yourselves, on a small scale, whenever you go to the seaside.  You will find that the shell which crawl on the rocks about high-water mark are different from those which you find at low-tide mark; and those again different from the shells which are brought up by the oyster-dredgers from the sea outside.  Now, the lower part of the clay, near here, contains shallow-water shells: but if you went forty miles to the eastward, you would find in the corresponding lower beds of the clay, deep-water shells, and far above them, shallow-water shells such as you find here: a fact which shows plainly that this end of the clay sea was shallowest, and therefore first filled up.

But again—and this is a very curious fact—between the time of the Plastic clays and sands, with their oyster-beds and black pebbles, and that of the London clay, great changes had taken place.  The Plastic clay and sands were deposited during a period of earthquake, of upheaval and subsidence of ancient lands; and therefore of violent currents and flood waves, seemingly rushing down from, or round the shores of that Wealden island to the south of us, on the shore of which island Odiham once stood.  We know this from the great irregularity of the beds: while the absence of that irregularity proves to us that the London clay was deposited in a quiet sea.

But more.  A great change in the climate of this country had taken place meanwhile; slowly perhaps: but still it had taken place.

In the lowest clay above the chalk are found at Reading many leaves, and buds, and seeds of trees, showing that there was dry land near; and these trees, as far as the best botanists can guess, were trees like those we have in England now.  Not of the same species, of course: but still trees belonging to a temperate climate, which had its regular warm summer and cold winter.

But before the London clay had been all deposited, this temperate climate had changed to a tropical one; and the plants and animals of the upper part of the London clay had begun to resemble rather those of the mouths of the African slave-rivers.

Extraordinary as this is, it is certainly true.

We know that the country near the mouth of the Thames, and probably the land round us here, was low rich soil, some half under water, some overflowed by rivers; some by fresh or brackish pools.  We know all this; for we find the shells which belong to a shallow sea, mixed with fresh-water ones.  We know, too, that the climate of this rich lowland was a tropical one.  We know that the neighbourhood of the Isle of Sheppey, at the mouth of the Thames, was covered with rich tropic vegetation; with screw pines and acacias, canes and gourds, tenanted by opossums, bats, and vultures: that huge snakes twined themselves along the ground, tortoises dived in the pools, and crocodiles basked on the muds, while the neighbouring seas swarmed with sharks as huge and terrible as those of a West Indian shore.

It is all very wonderful, ladies and gentlemen: but be it is: and all we can say is, with the Mussulman—“God is great.”

And then—when, none knows but God—there came a time in which some convulsion of nature changed the course of the sea currents, and probably destroyed a vast tract of land between England and France, and probably also, that sunken island of Atlantis of which old Plato dreamed—the vast tract which connected for ages Ireland, Cornwall, Brittany, and Portugal.  That convulsion covered up the rich clays with those barren sands and gravels, which now rise in flat and dreary steppes, on the Beacon Hill, Aldershot Moors, Hartford Bridge Flat, Frimley ridges, and Windsor Forest.  That rich old world was all swept away, and instead of it desolation and barrenness, piling up slowly on its ruins a desert of sand and shingle, rising inch by inch out of a lifeless sea.  There is something very awful to me in the barrenness of those Bagshot sands, after the rich tropic life of the London clay.  Not a fossil is to be found in them for miles.  Save a few shells, I believe, near Pirbright, there is not a hint that a living being inhabited that doleful sea.

But do not suppose, gentlemen and ladies, that we have yet got our gravel-pit made, or that the way-worn pebbles of which it is composed are near the end of their weary journey.  Poor old stones!  Driven out of their native chalk, rolled for ages on a sea-beach, they have tried to get a few centuries’ sleep in the Eocene sands on the top of the chalk hills behind us, while the London clay was being deposited peacefully in the tropic sea below; and behold, they are swept out, once more, and hurled pell-mell upon the clay, two hundred feet over our heads.

Over our heads, remember.  We have come now to a time when Hartford Bridge Flats stretched away to the Beacon Hill, and many a mile to the south-eastward—even down into Kent, and stretched also over Winchfield and Dogmersfield hither.

What broke them up?  What furrowed out their steep side-valleys?  What formed the magnificent escarpment of the Beacon Hill, or the lesser one of Finchamstead Ridges?  What swept away all but a thin cap of them on the upper part of Dogmersfield Park, another under Winchfield House; another at Bearwood, and so forth?

The convulsions of a third world; more fertile in animal life than those which preceded it: but also, more terrible and rapid, if possible, in its changes.

Of this third world, the one which (so to speak) immediately preceded our own, we know little yet.  Its changes are so complicated that geologists have as yet hardly arranged them.  But what we can see, I will sketch for you shortly.

A great continent to the south—England, probably an island at the beginning of the period, united to the continent by new beds—the Mammoth ranging up to where we now stand.

Then a period of upheaval.  The German Ocean becomes dry land.  The Thames, a far larger river than now, runs far eastward to join the Seine, and the Rhine, and other rivers, which altogether flow northward, in one enormous stream, toward the open sea between Scotland and Norway.

And with this, a new creation of enormous quadrupeds, as yet unknown.  Countless herds of elephants pastured by the side of that mighty river, where now the Norfolk fisherman dredges their teeth and bones far out in open sea.  The hippopotamus floundered in the Severn, the rhinoceros ranged over the south-western counties; enormous elk and oxen, of species now extinct, inhabited the vast fir and larch forests which stretched from Norfolk to the farthest part of Wales; hyenas and bears double the size of our modern ones, and here and there the sabre-toothed tiger, now extinct, prowled out of the caverns in the limestone hills, to seek their bulky prey.

We see, too, a period—whether the same as this, or after it, I know not yet—in which the mountains of Wales and Cumberland rose to the limits of eternal frost, and Snowdon was indeed Snowdon, an alp down whose valleys vast glaciers spread far and wide; while the reindeer of Lapland, the marmot of the Alps, and the musk ox of Hudson’s Bay, fed upon alpine plants, a few of whose descendants still survive, as tokens of the long past age of ice.  And at every successive upheaval of the western mountains the displaced waters of the ocean swept over the lower lands, filling the valley of the Thames and of the Wey with vast beds of drift gravel, containing among its chalk flints, fragments of stone from every rock between here and Wales, teeth of elephants, skulls of ox and musk ox; while icebergs, breaking away from the glaciers of the Welsh Alps, sailed down over the spot where we now are, dropping their imbedded stones and silt, to confuse more utterly than before the records of a world rocking and throbbing above the shocks of the nether fire.

At last the convulsions get weak.  The German Ocean becomes sea once more; the north-western Alps sink again to a level far lower even than their present one; only to rise again, but not so high as before; sea-beaches and sea-shells fill many of our lower valleys; whales by hundreds are stranded (as in the Farnham vale) where is now dry land.  Gradually the sunken land begins to rise again, and falls perhaps again, and rises again after that, more and more gently each time, till as it were the panting earth, worn out with the fierce passions of her fiery youth, has sobbed herself to sleep once more, and this new world of man is made.  And among it, I know not when, or by what diluvial wave out of hundreds which swept the Pleistocene earth, was deposited our little gravel-pit, from which we started on our journey through three worlds.

When?

Enough for us that He knows when, in whose hand are the times and the seasons—God the Father of the spirits of all flesh.

And now, ladies and gentlemen, take from hence a lesson.  I have brought you a long and a strange road.  Starting from this seemingly uninteresting pit, we have come upon the records of three older worlds, and on hints of worlds far older yet.  We have come to them by no theories, no dreams of the fancy, but by plain honest reasoning, from plain honest facts.  That wonderful things had happened, we could see: but why they had happened, we saw not.  When we began to ask the reason of this thing or of that, remember how we had to stop, and laying our hands upon our mouths, only say with the Mussulman: “God is great.”  We pick our steps, by lanthorn light indeed, and slowly, but still surely and safely, along a dark and difficult road: but just as we are beginning to pride ourselves on having found our way so cleverly, we come to an edge of darkness; and see before our feet a bottomless abyss, down which our feeble lanthorn will not throw its light a yard.

Such is true science.  Is it a study to make men conceited and self-sufficient?  Believe it not.  If a scientific man, or one who calls himself so, be conceited, the conceit was there before the science; part of his natural defects: and if it stays there long after he has really given himself to the patient study of nature, then is he one of those of whom Solomon has said: “Though you pound a fool in a mortar among wheat with a pestle, yet will not his folly depart from him.”

For what more fit to knock the conceit out of a student, than being pounded by these same hard facts—which tell him just enough to let him know—how little he knows?  What more fit to make a man patient, humble, reverent, than being stopped short, as every man of science is, after each half-dozen steps, by some tremendous riddle which he cannot explain—which he may have to wait years to get explained—which as far as he can see will never be explained at all?

The poet says: “An undevout astronomer is mad,” and he says truth.  It is only those who know a little of nature, who fancy that they know much.  I have heard a young man say, after hearing a few popular chemical lectures, and seeing a few bottle and squirt experiments: Oh, water—water is only oxygen and hydrogen!—as if he knew all about it.  While the true chemist would smile sadly enough at the youth’s hasty conceit, and say in his heart: “Well, he is a lucky fellow.  If he knows all about it, it is more than I do.  I don’t know what oxygen is, or hydrogen, either.  I don’t even know whether there are any such things at all.  I see certain effects in my experiments which I must attribute to some cause, and I call that cause oxygen, because I must call it something; and other effects which I must attribute to another cause, and I call that hydrogen.  But as for oxygen, I don’t know whether it really exists.  I think it very possible that it is only an effect of something else—another form of a something, which seems to make phosphorus, iodine, bromine, and certain other substances: and as for hydrogen—I know as little about it.  I don’t know but what all the metals, gold, silver, iron, tin, sodium, potassium, and so forth, are not different forms of hydrogen, or of something else which is the parent of hydrogen.  In fact, I know but very little about the matter; except this, that I do know very little; and that the more I experiment, and the more I analyse, the more unexpected puzzles and wonders I find, and the more I expect to find till my dying day.  True, I know a vast number of facts and laws, thank God; and some very useful ones among them: but as to the ultimate and first causes of those facts and laws, I know no more than the shepherd-boy outside; and can say no more than he does, when he reads in the Psalms at school: “I, and all around me, are fearfully and wonderfully made; marvellous are Thy works, and that my soul knoweth right well.”

And so, my friends, though I have seemed to talk to you of great matters this night; of the making and the destruction of world after world: yet what does all I have said come to?  I have not got one step beyond what the old Psalmist learnt amid the earthquakes and volcanoes of the pastures and the forests of Palestine, three thousand years ago.  I have not added to his words; I have only given you new facts to prove that he had exhausted the moral lesson of the subject, when he said:

These all wait upon thee, that thou mayest give them their meat in due season.

Thou givest, and they gather: thou openest thy hand, and they are filled with good.

Thou hidest thy face, they are troubled; thou takest away their breath; they die and return to their dust.

Thou sendest forth thy spirit, they are created; and thou renewest the face of the earth.

But—The glory of the Lord shall endure for ever.  The Lord shall rejoice in his works.  Amen.

HOW TO STUDY NATURAL HISTORY 7

Ladies and gentlemen, I speak to you to-night as to persons assembled, somewhat, no doubt, for amusement, but still more for instruction.  Institutions such as this were originally founded for the purpose of instruction; to supply to those who wish to educate themselves some of the advantages of a regular course of scholastic or scientific training, by means of classes and of lectures.

I myself prize classes far higher than I do lectures.  From my own experience, a lecture is often a very dangerous method of teaching; it is apt to engender in the mind of men ungrounded conceit and sciolism, or the bad habit of knowing about subjects without really knowing the subject itself.  A young man hears an interesting lecture, and carries away from it doubtless a great many new facts and results: but he really must not go home fancying himself a much wiser man; and why?  Because he has only heard the lecturer’s side of the story.  He has been forced to take the facts and the results on trust.  He has not examined the facts for himself.  He has had no share in the process by which the results were arrived at.  In short, he has not gone into the real scientia, that is, the “knowing” of the matter.  He has gained a certain quantity of second-hand information: but he has gained nothing in mental training, nothing in the great “art of learning,” the art of finding out things for himself, and of discerning truth from falsehood.  Of course, where the lecture is a scientific one, illustrated by diagrams, this defect is not so extreme: but still the lecturer who shows you experiments, is forced to choose those which shall be startling and amusing, rather than important; he is seldom or never able, unless he is a man of at once the deepest science and the most extraordinary powers of amusing, to give you those experiments in the proper order which will unfold the subject to you step by step; and after all, an experiment is worth very little to you, unless you perform it yourself, ask questions about it, or vary it a little to solve difficulties which arise in your own mind.

Now mind—I do not say all this to make you give up attending lectures.  Heaven forbid.  They amuse, that is, they turn the mind off from business; they relax it, and as it were bathe and refresh it with new thoughts, after the day’s drudgery or the day’s commonplaces; they fill it with pleasant and healthful images for afterthought.  Above all, they make one feel what a fair, wide, wonderful world one lives in; how much there is to be known, and how little one knows; and to the earnest man suggest future subjects of study.  I only ask you not to expect from lectures what they can never give; but as to what they can give, I consider, I assure you, the lecturer’s vocation a most honourable one in the present day, even if we look on him as on a mere advertiser of nature’s wonders.  As such I appear here to-night; not to teach you natural history; for that you can only teach yourselves: but to set before you the subject and its value, and if possible, allure some of you to the study of it.

I have said that lectures do not supply mental training; that only personal study can do that.  The next question is, What study?  And that is a question which I do not answer in a hurry, when I say, The study of natural history.  It is not, certainly, a study which a young man entering on the business of self-education would be likely to take up.  To him, naturally, man is the most important subject.  His first wish is to know the human world; to know what men are, what they have thought, what they have done.  And therefore, you find that poetry, history, politics, and philosophy are the matters which most attract the self-guided student.  I do not blame him, but he seems to me to be beginning at the middle, rather than at the beginning.  I fell into the same fault myself more than once, when I was younger, and meddled in matters too high for me, instead of refraining my soul, and keeping it low; so I can sympathise with others who do so.  But I can assure them that they will find such lofty studies do them good only in proportion as they have first learnt the art of learning.  Unless they have learnt to face facts manfully, to discriminate between them skilfully, to draw conclusions from them rigidly; unless they have learnt in all things to look, not for what they would like to be true, but for what is true, because God has done it, and it cannot be undone—then they will be in danger of taking up only the books which suit their own prejudices—and every one has his prejudices—and using them, not to correct their own notions, but to corroborate and pamper them; to confirm themselves in their first narrow guesses, instead of enlarging those guesses into certainty.  The son of a Tory turn will read Tory books, the son of a Radical turn Radical books; and the green spectacles of party and prejudice will be deepened in hue as he reads on, instead of being thrown away for the clear white glass of truth, which will show him reason in all honest sides, and good in all honest men.