,the ,fairy-,land of ,science ,arabella ,b4 ,buckley ,,table ,,of ,,contents ,lecture ,i ,the ,fairy-,land of ,science2 ,how to ,enter ,it2 ,how to ,use ,it2 ,and ,how to ,enjoy ,it ,lecture ,,ii ,sunbeams1 and the ,work ,they ,do ,lecture ,,iii ,the ,aerial ,ocean in ,which ,we ,live ,lecture ,,iv ,a ,drop of ,water on its ,travels ,lecture ,v ,the ,two ,great ,sculptors - ,water and ,ice ,lecture ,,vi ,the ,voices of ,nature1 and ,how ,we ,hear ,them ,lecture ,,vii ,the ,life of a ,primrose ,lecture ,,viii ,the ,history of a ,piece of ,coal ,lecture ,,ix ,bees in the ,hive ,lecture ,x ,bees and ,flowers ,week #a ,,lecture ,i ,,how ,,to ,,enter ,,it2 ,,how ,,to ,,use ,,it2 ,,and ,,how ,,to ,,enjoy ,,it ,i ,,have promised to introduce you today to the fairy-land of science - a somewhat bold promise1 seeing that most of you probably look upon science as a bundle of dry facts1 while fairy- land is all that is beautiful1 and full of poetry and imagination4 ,but ,i thoroughly believe myself1 and hope to prove to you1 that science is full of beautiful pictures1 of real poetry1 and of wonder-working fairies2 and what is more1 ,i promise you they shall be true fairies1 whom you will love just as much when you are old and greyheaded as when you are young2 for you will be able to call them up wherever you wander by land or by sea1 through meadow or through wood1 through water or through air2 and though they themselves will always remain invisible1 yet you will see their wonderful poet at work everywhere around you4 ,let us first see for a moment what kind of tales science has to tell1 and how far they are equal to the old fairy tales we all know so well4 ,who does not remember the tale of the ,sleeping ,beauty in the ,wood1 and how under the spell of the angry fairy the maiden pricked herself with the spindle and slept a hundred years8 ,how the horses in the stall1 the dogs in the court-yard1 the doves on the roof1 the cook who was boxing the scullery boy's ears in the kitchen1 and the king and queen with all their courtiers in the hall remained spell-bound1 while a thick hedge grew up all round the castle and all within was still as death4 ,but when the hundred years had passed the valiant prince came1 the thorny hedge opened before him bearing beautiful flowers2 and he1 entering the castle1 reached the room where the princess lay1 and with one sweet kiss raised her and all around her to life again4 ,can science bring any tale to match this8 ,tell me1 is there anything in this world more busy and active than water1 as it rushes along in the swift brook1 or dashes over the stones1 or spouts up in the fountain1 or trickles down from the roof1 or shakes itself into ripples on the surface of the pond as the wind blows over it8 ,but have you never seen this water spell-bound and motionless8 ,look out of the window some cold frosty morning in winter1 at the little brook which yesterday was flowing gently past the house1 and see how still it lies1 with the stones over which it was dashing now held tightly in its icy grasp4 ,notice the wind-ripples on the pond2 they have become fixed and motionless4 ,look up at the roof of the house4 ,there1 instead of living doves merely charmed to sleep1 we have running water caught in the very act of falling and turned into transparent icicles1 decorating the eaves with a beautiful crystal fringe4 ,on every tree and bush you will catch the water- drops napping1 in the form of tiny crystals2 while the fountain looks like a tree of glass with long down-hanging pointed leaves4 ,even the damp of your own breath lies rigid and still on the window-pane frozen into delicate patterns like fern-leaves of ice4 ,all this water was yesterday flowing busily1 or falling drop by drop1 or floating invisibly in the air2 now it is all caught and spell-bound - by whom8 ,by the enchantments of the frost-giant who holds it fast in his grip and will not let it go4 ,but wait awhile1 the deliverer is coming4 ,in a few weeks or days1 or it may be in a few hours1 the brave sun will shine down2 the dull-grey1 leaden sky will melt before his1 as the hedge gave way before the prince in the fairy tale1 and when the sunbeam gently kisses the frozen water it will be set free4 ,then the brook will flow rippling on again2 the frost-drops will be shaken down from the trees1 the icicles fall from the roof1 the moisture trickle down the window-pane1 and in the bright1 warm sunshine all will be alive again4 ,is not this a fairy tale of nature8 and such as these it is which science tells4 ,again1 who has not heard of ,catskin1 who came out of a hollow tree1 bringing a walnut containing three beautiful dresses - the first glowing as the sun1 the second pale and beautiful as the moon1 the third spangled like the star-lit sky1 and each so fine and delicate that all three could be packed into a walnut shell2 and each one of these tiny structures is not the mere dress but the home of a living animal4 ,it is a tiny1 tiny shell-palace made of the most delicate lacework1 each pattern being more beautiful than the last2 and what is more1 the minute creature that lives in it has built it out of the foam of the sea1 though he himself is nothing more than a drop of jelly4 ,lastly1 anyone who has read the ',wonderful ,travellers' must recollect the man whose sight was so keen that he could hit the eye of a fly sitting on a tree two miles away4 ,but tell me1 can you see gas before it is lighted1 even when it is coming out of the gas-jet close to your eyes8 ,yet1 if you learn to use that wonderful instrument the spectroscope1 it will enable you to tell one kind of gas from another1 even when they are both ninety-one millions of miles away on the face of the sun2 nay more1 it will read for you the nature of the different gases in the far distant stars1 billions of miles away1 and actually tell you whether you could find there any of the same metals which we have on the earth4 ,we might find hundreds of such fairy tales in the domain of science1 but these three will serve as examples1 and we much pass on to make the acquaintance of the science-fairies themselves1 and see if they are as real as our old friends4 ,tell me1 why do you love fairy-land8 what is its charm8 ,is it not that things happen so suddenly1 so mysteriously1 and without man having anything to do with it8 ,in fairy-land1 flowers blow1 houses spring up like ,aladdin's palace in a single night1 and people are carried hundreds of miles in an instant by the touch of a fairy wand4 ,and then this land is not some distant country to which we can never hope to travel4 ,it is here in the midst of us1 only our eyes must be opened or we cannot see it4 ,ariel and ,puck did not live in some unknown region4 ,on the contrary1 ,ariel's song is ,where the bee sucks1 there suck ,i2 ,in a cowslip's bell ,i lie2 ,there ,i couch when owls do cry4 ,on the bat's back ,i do fly1 ,after summer1 merrily4 ,the peasant falls asleep some evening in a wood and his eyes are opened by a fairy wand1 so that he sees the little goblins and imps dancing around him on the green sward1 sitting on mushrooms1 or in the heads of the flowers1 drinking out of acorn-cups1 fighting with blades of grass1 and riding on grasshoppers4 ,so1 too1 the gallant knight1 riding to save some poor oppressed maiden1 dashes across the foaming torrent2 and just in the middle1 as he is being swept away1 his eyes are opened1 and he sees fairy water-nymphs soothing his terrified horse and guiding him gently to the opposite shore4 ,they are close at hand1 these sprites1 to the simple peasant or the gallant knight1 or to anyone who has the gift of the fairies and can see them4 but the man who scoffs at them1 and does not believe in them or care for them1 he never sees them4 ,only now and then they play him an ugly trick1 leading him into some treacherous bog and leaving him to get out as he may4 ,now1 exactly all this which is true of the fairies of our childhood is true too of the fairies of science4 ,there are forces around us1 and among us1 which ,i shall ask you to allow me to call fairies1 and these are ten thousand times more wonderful1 more magical1 and more beautiful in their work1 than those of the old fairy tales4 ,they1 too1 are invisible1 and many people live and die without ever seeing them or caring to see them4 ,these people go about with their eyes shut1 either because they will not open them1 or because no one has taught them how to see4 ,they fret and worry over their own little work and their own petty troubles1 and do not know how to rest and refresh themselves1 by letting the fairies open their eyes and show them the calm sweet picture of nature4 ,they are like ,peter ,bell of whom ,wordsworth wrote3- ,a primrose by a river's brim ,a yellow primrose was to him1 ,and it was nothing more4 ,but we will not be like these1 we will open our eyes and ask1 ,what are these forces or fairies1 and how can we see them8 ,just go out into the country1 and sit down quietly and watch nature at work4 ,listen to the wind as it blows1 look at the clouds rolling overhead1 and waves rippling on the pond at your feet4 ,hearken to the brook as it flows by1 watch the flower-buds opening one by one1 and then ask yourself1 ,how all this is done8 ,go out in the evening and see the dew gather drop by drop upon the grass1 or trace the delicate hoar-frost crystals which bespangle every blade on a winter's morning4 ,look at the vivid flashes of lightening in a storm1 and listen to the pealing thunder3 and then tell me1 by what machinery is all this wonderful work done8 ,man does none of it1 neither could he stop it if he were to try2 for it is all the work of those invisible forces or fairies whose acquaintance ,i wish you to make4 ,day and night1 summer and winter1 storm or calm1 these fairies are at work1 and we may hear them and know them1 and make friends of them if we will4 ,there is only one gift we must have before we can learn to know them - we must have imagination4 ,i do not mean mere fancy1 which creates unreal images and impossible monsters1 but imagination1 the power of making pictures or images in our mind1 of that which is1 though it is invisible to us4 ,most children have this glorious gift1 and love to picture to themselves all that is told them1 and to hear the same tale over and over again till they see every bit of it as if it were real4 ,this is why they are sure to love science it its tales are told them aright2 and ,i1 for one1 hope the day may never come when we may lose that childish clearness of vision1 which enables us through the temporal things which are seen1 to realize those eternal truths which are unseen4 ,if you have this gift of imagination come with me1 and in these lectures we will look for the invisible fairies of nature4 ,watch a shower of rain4 ,where do the drops come from8 and why are they round1 or rather slightly oval8 ,in our fourth lecture we shall se that the little particles of water of which the raindrops are made1 were held apart and invisible in the air by heat1 one of the most wonderful of our forces99 or fairies1 till the cold wind passed by and chilled the air4 ,then1 when there was no longer so much heat1 another invisible force1 cohesion1 which is always ready and waiting1 seized on the tiny particles at once1 and locked them together in a drop1 the closest form in which they could lie4 ,then as the drops became larger and larger they fell into the grasp of another invisible force1 gravitation1 which dragged them down to the earth1 drop by drop1 till they made a shower of rain4 ,pause for a moment and think4 ,you have surely heard of gravitation1 by which the sun holds the earth and the planets1 and keeps them moving round him in regular order8 ,well1 it is this same gravitation which is a t work also whenever a shower of rain falls to the earth4 ,who can say that he is not a great invisible giant1 always silently and invisibly toiling in great things and small whether we wake or sleep8 997,i am quite aware of the danger incurred by using this word force1 especially in the plural2 and how even the most modest little book may suffer at the hands of scientific purists by employing it rashly4 ,as1 however1 the better term energy would not serve here1 ,i hope ,i may be forgiven for retaining the much- abused term1 especially as ,i sin in very good company47 ,now the shower is over1 the sun comes out and the ground is soon as dry as though no rain had fallen4 ,tell me2 what has become of the rain-drops8 ,part no doubt have sunk into the ground1 and as for the rest1 why you will say the sun has dried them up4 ,yes1 but how8 ,the sun is more than ninety-one millions of miles away2 how has he touched the rain-drops8 ,have you ever heard that invisible waves are travelling every second over the space between the sun and us8 ,we shall see in the next lecture how these waves are the sun's messengers to the earth1 and how they tear asunder the rain-drops on the ground1 scattering them in tiny particles too small for us to see1 and bearing them away to the clouds4 ,here are more invisible fairies working every moment around you1 and you cannot even look out of the window without seeing the work they are doing4 ,if1 however1 the day is cold and frosty1 the water does not fall in a shower of rain2 it comes down in the shape of noiseless snow4 ,go out after such a snow-shower1 on a calm day1 and look at some of the flakes which have fallen2 you will see1 if you choose good specimens1 that they are not mere masses of frozen water1 but that each one is a beautiful six-pointed crystal star4 ,how have these crystals been built up8 ,what power has been at work arranging their delicate forms8 ,in the fourth lecture we shall see that up in the clouds another of our invisible fairies1 which1 for want of a better name1 we call the force of crystallization1 has caught hold of the tiny particles of water before cohesion had made them into round drops1 and there silently but rapidly1 has moulded them into those delicate crystal starts know as snowflakes4 ,and now1 suppose that this snow-shower has fallen early in ,february2 turn aside for a moment from examining the flakes1 and clear the newly-fallen snow from off the flower-bed on the lawn4 ,what is this little green tip peeping up out of the ground under the snowy covering8 ,it is a young snowdrop plant4 ,can you tell me why it grows8 where it finds its food8 what makes it spread out its leaves and add to its stalk day by day8 ,what fairies are at work here8 ,first there is the hidden fairy life1 and of her even our wisest men know but little4 ,but they know something of her way of working1 and in ,lecture ,,vii we shall learn how the invisible fairy sunbeams have been buy here also2 how last year's snowdrop plant caught them and stored them up in it's bulb1 and how now in the spring1 as soon as warmth and moisture creep down into the earth1 these little imprisoned sun-waves begin to be active1 stirring up the matter in the bulb1 and making it swell and burst upwards till it sends out a little shoot through the surface of the soil4 ,then the sun-waves above-ground take up the work1 and form green granules in the tiny leaves1 helping them to take food out of the air1 while the little rootlets below are drinking water out of the ground4 ,the invisible life and invisible sunbeams are busy here1 setting actively to work another fairy1 the force of chemical attraction1 and so the little snowdrop plant grows and blossoms1 without any help from you or me4 ,week #b ,one picture more1 and then ,i hope you will believe in my fairies4 ,from the cold garden1 you run into the house1 and find the fire laid indeed in the grate1 but the wood dead and the coals black1 waiting to be lighted4 ,you strike a match1 and soon there is a blazing fire4 ,where does the heat come from8 ,why do the coals burn and give out a glowing light8 ,have you not read of gnomes buried down deep in the earth1 in mines1 and held fast there till some fairy wand has released them1 and allowed them to come to earth again8 ,well1 thousands and millions of years ago1 those coals were plants2 and like the snowdrop in the garden of to-day1 they caught the sunbeams and worked them into their leaves4 ,then the plants died and were buried deep in the earth and the sunbeams with them2 and like the gnomes they lay imprisoned till the coals were dug out by the miners1 and brought to your grate2 and just now you yourself took hold of the fairy wand which was to release them4 ,you struck a match1 and its atoms clashing with atoms of oxygen in the air1 set the invisible fairies heat and chemical attraction to work1 and they were soon busy within the wood and the coals causing their atoms too to clash2 and the sunbeams1 so long imprisoned1 leapt into flame4 ,then you spread out your hands and cried1 ,oh1 how nice and warm6 and little thought that you were warming yourself with the sunbeams of ages and ages ago4 ,this is no fancy tale2 it is literally true1 as we shall see in ,lecture ,,viii1 that the warmth of a coal fire could not exist if the plants of long ago had not used the sunbeams to make their leaves1 holding them ready to give up their warmth again whenever those crushed leaves are consumed4 ,now1 do you believe in1 and care for1 my fairy-land8 ,can you see in your imagination fairy ',cohesion' ever ready to lock atoms together when they draw very near to each other3 or fairy ',gravitation' dragging rain-drops down to the earth3 or the fairy of ',crystallization' building up the snow-flakes in the clouds8 ,can you picture tiny sunbeam-waves of light and heat travelling from the sun to the earth8 ,do you care to know how another strange fairy1 ',electricity1' flings the lightning across the sky and causes the rumbling thunder8 ,would you like to learn how the sun makes pictures of the world on which he shines1 so that we can carry about with us photographs or sun-pictures of all the beautiful scenery of the earth8 ,and have you any curiosity about ',chemical action1' which works such wonders in air1 and land1 and sea8 ,if you have any wish to know and make friends of these invisible forces1 the next question is ,how are you to enter the fairy-land of science8 ,there is but one way4 ,like the knight or peasant in the fairy tales1 you must open you eyes4 ,there is no lack of objects1 everything around you will tell some history if touched with the fairy wand of imagination4 ,i have often thought1 when seeing some sickly child drawn along the street1 lying on its back while other children romp and play1 how much happiness might be given to sick children at home or in hospitals1 if only they were told the stories which lie hidden in the things around them4 ,they need not even move from their beds1 for sunbeams can fall on them there1 and in a sunbeam there are stories enough to occupy a month4 ,the fire in the grate1 the lamp by the bedside1 the water in the tumbler1 the fly on the ceiling above1 the flower in the vase on the table1 anything1 everything1 has its history1 and can reveal to us nature's invisible fairies4 ,only you must with to see them4 ,if you go through the world looking upon everything only as so much to eat1 to drink1 and to use1 you will never see the fairies of science4 ,but if you ask yourself why things happen1 and how the great ,god above us has made and governs this world of ours2 ,if you listen to the wind1 and care to learn why it blows2 if you ask the little flower why it opens in the sunshine and closes in the storm2 and if when you find questions you cannot answer1 you will take the trouble to hunt out in books1 or make experiments to solve your own questions1 then you will learn to know and love those fairies4 ,mind1 ,i do not advise you to be constantly asking questions of other people2 for often a question quickly answered is quickly forgotten1 but a difficulty really hunted down is a triumph for ever4 ,for example1 if you ask why the rain dries up from the ground1 most likely you will be answered1 that the sun dries it1 and you will rest satisfied with the sound of the words4 ,but if you hold a wet handkerchief before the fire and see the damp rising out of it1 then you have some real idea how moisture may be drawn up by heat from the earth4 ,a little foreign niece of mine1 only four years old1 who could scarcely speak ,english plainly1 was standing one morning near the bedroom window and she noticed the damp trickling down the window-pane4 ,auntie1 she said1 what for it rain inside8 ,it was quite useless to explain to her in words1 how our breath had condensed into drops of water upon the cold glass2 but ,i wiped the pane clear1 and breathed on it several times4 ,when new drops were formed1 ,i said1 ,cissy and auntie have done like this all night in the room4 ,she nodded her little head and amused herself for a long time breathing on the window-pane and watching the tiny drops2 and about a month later1 when we were travelling back to ,italy1 ,i saw her following the drops on the carriage window with her little finger1 and heard her say quietly to herself1 ,cissy and auntie made you4 ,had not even this little child some real picture in her mind of invisible water coming from her mouth1 and making drops upon the window-pane8 ,then again1 you must learn something of the language of science4 ,if you travel in a country with no knowledge of its language1 you can learn very little about it3 and in the same way if you are to go to books to find answers to your questions1 you must know something of the language they speak4 ,you need not learn hard scientific names1 for the best books have the fewest of these1 but you must really understand what is meant by ordinary words4 ,for example1 how few people can really explain the difference between a solid1 such as the wood of the table2 a liquid1 as water2 and a gas1 such as ,i can let off from this gas-jet by turning the tap4 ,and yet any child can make a picture of this in his mind if only it has been properly put before him4 ,all matter in the world is made up of minute parts or particles2 in a solid these particles are locked together so tightly that you must tear them forcibly apart if you with to alter the shape of the solid piece4 ,if ,i break or bend this wood ,i have to force the particles to move round each other1 and ,i have great difficulty doing it4 ,but in a liquid1 though the particles are still held together1 they do not cling so tightly1 but are able to roll or glide round each other1 so that when you pour water out of a cup on to a table1 it loses its cuplike shape and spreads itself out flat4 ,lastly1 in a gas the particles are no longer held together at all1 but they try to fly away from each other2 and unless you shut a gas in tightly and safely1 it will soon have spread all over the room4 ,a solid1 therefore1 will retain the same bulk and shape unless you forcibly alter it2 a liquid will retain the same bulk1 but no the same shape if it be left free2 a gas will not retain either the same bulk or the same shape1 but will spread over as large a space as it can find wherever it can penetrate4 ,such simple things as these you must learn from books and by experiment4 ,then you must understand what is meant by chemical attraction2 and though ,i can explain this roughly here1 you will have to make many interesting experiments before you will really learn to know this wonderful fairy power4 ,if ,i dissolve sugar in water1 though it disappears it still remains sugar1 and does not join itself to the water4 ,i have only to let the cup stand till the water dries1 and the sugar will remain at the bottom4 ,there has been no chemical attraction here4 ,but now ,i will put something else in water which will call up the fairy power4 ,here is a little piece of the metal potassium1 one of the simple substances of the earth2 that is to say1 we cannot split it up into other substances1 wherever we find it1 it is always the same4 ,now if ,i put this piece of potassium on the water it does not disappear quietly like the sugar4 ,see how it rolls round and round1 fizzing violently with a blue flame burning round it1 and at last goes off with a pop4 ,what has been happening here8 ,you must first know that water is made of two substances1 hydrogen and oxygen1 and these are not merely held together1 but are joined to completely that they have lost themselves and have become water2 and each atom of water is made of two atoms of hydrogen and one of oxygen4 ,now the metal potassium is devotedly fond of oxygen1 and the moment ,i threw it on the water it called the fairy chemical attraction' to help it1 and dragged the atoms of oxygen out of the water and joined them to itself4 ,in doing this it also caught part of the hydrogen1 but only half1 and so the rest was left out in the cold4 ,no1 not in the cold6 for the potassium and oxygen made such a great heat in clashing together that the rest of the hydrogen became very hot indeed1 and sprang into the air to find some other companion to make up for what it had lost4 ,here it found some free oxygen floating about1 and it seized upon it so violently1 that they made a burning flame1 while the potassium with its newly found oxygen and hydrogen sank down quietly into the water as potash4 ,and so you see we have got quite a new substance potash in the basin2 made with a great deal of fuss by chemical attraction drawing different atoms together4 ,when you can really picture this power to yourself it will help you very much to understand what you read and observe about nature4 ,next1 as plants grow around you on every side1 and are of so much importance in the world1 you must also learn something of the names of the different parts of a flower1 so that you may understand those books which explain how a plant grows and lives and forms its seeds4 ,you must also know the common names of the parts of an animal1 and of your own body1 so that you may be interested in understanding the use of the different organs2 how you breathe1 and how your blood flows2 how one animal walks1 another flies1 and another swims4 ,then you must learn something of the various parts of the world1 so that you may know what is meant by a river1 a plain1 a valley1 or a delta4 ,all these things are not difficult1 you can learn them pleasantly from simple books on physics1 chemistry1 botany1 physiology1 and physical geography2 and when you understand a few plain scientific terms1 then all by yourself1 if you will open your eyes and ears1 you may wander happily in the fairy-land of science4 ,then wherever you go you will find ,tongues in trees1 books in the running brooks ,sermons in stones1 and good in everything4 ,and now we come to the last part of our subject4 ,when you have reached and entered the gates of science1 how are you to use and enjoy this new and beautiful land8 ,this is a very important question for you may make a twofold use of it4 ,if you are only ambitious to shine in the world1 you may use it chiefly to get prizes1 to be at the top of your class1 or to pass in examinations2 but if you also enjoy discovering its secrets1 and desire to learn more and more of nature and to revel in dreams of its beauty1 then you will study science for its own sake as well4 ,now it is a good thing to win prizes and be at the top of your class1 for it shows that you are industrious2 it is a good thing to pass well in examinations 1 for it show that you are accurate2 but if you study science for this reason only1 do not complain if you find it full1 and dry1 and hard to master4 ,you may learn a great deal that is useful1 and nature will answer you truthfully if you ask you questions accurately1 but she will give you dry facts1 just such as you ask for4 ,if you do not love her for herself she will never take you to her heart4 ,this is the reason why so many complain that science is dry and uninteresting4 ,they forget that though it is necessary to learn accurately1 for so only we can arrive at truth1 it is equally necessary to love knowledge and make it lovely to those who learn1 and to do this we must get at the spirit which lies under the facts4 ,what child which loves its mother's face is content to know only that she has brown eyes1 a straight nose1 a small mouth1 and hair arranged in such and such a manner8 ,no1 it knows that its mother has the sweetest smile of any woman living2 that her eyes are loving1 her kiss is sweet1 and that when she looks grave1 then something is wrong which must be put right4 ,and it is in this way that those who wish to enjoy the fairy-land of science must love nature4 ,it is well to know that when a piece of potassium is thrown on water the change which takes place is expressed by the formula ,k ,h#b,o ,,kho ,h4 ,but it is better still to have a mental picture of the tiny atoms clasping each other1 and mingling so as to make a new substance1 and to feel how wonderful are the many changing forms of nature4 ,it is useful to be able to classify a flower and to know that the buttercup belongs to the ,family ,ranunculaceae1 with petals free and definite1 stamens hypogynous and indefinite1 pistil apocarpous4 ,but it is far sweeter to learn about the life of the little plant1 to understand why its peculiar flower is useful to it1 and how it feeds itself1 and makes its seed4 ,no one can love dry facts2 we must clothe them with real meaning and love the truths they tell1 if we wish to enjoy science4 ,let us take an example to show this4 ,i have here a branch of white coral1 a beautiful1 delicate piece of nature's work4 ,we will begin by copying a description of it from one of those class-books which suppose children to learn words like parrots1 and to repeat them with just as little understanding4 ,coral is formed by an animal belonging to the kingdom of ,radiates1 sub-kingdom ,polypes4 ,the soft body of the animal is attached to a support1 the mouth opening upwards in a row of tentacles4 ,the coral is secreted in the body of the polyp out of the carbonate of lime in the sea4 ,thus the coral animalcule rears its polypidom or rocky structure in warm latitudes1 and constructs reefs or barriers round islands4 ,it is limited in rage of depth from #be to #cj fathoms4 ,chemically considered1 coral is carbonate of like2 physiologically1 it is the skeleton of an animal2 geographically1 it is characteristic of warm latitudes1 especially of the ,pacific ,ocean4 ,this description is correct1 and even fairly complete1 if you know enough of the subject to understand it4 ,but tell me1 does it lead you to love my piece of coral8 ,have you any picture in your mind of the coral animal1 its home1 or its manner of working8 ,but now1 instead of trying to master this dry1 hard passage1 take ,mr4 ,huxley's penny lecture on ',coral and ,coral ,reefs1' and with the piece of coral in your hand try really to learn its history4 ,you will then be able to picture to yourself the coral animal as a kind of sea-anemone1 something like those which you have often seen1 like red1 blue1 or green flowers1 putting out feelers in sea-water on our coasts1 and drawing in the tiny sea-animals to digest them in that bag of fluid which serves the sea-anemone as a stomach4 ,you will learn how this curious jelly animal can split itself in two1 and so form two polyps1 or send a bud out of its side and so grow up into a kind of tree or bush of polyps1 or how it can hatch little eggs inside it and throw out young ones from its mouth1 provided with little hairs1 by means of which they swim to new resting-places4 ,you will learn the difference between the animal which builds up the red coral as its skeleton1 and the group of animals which build up the white2 and you will look with new interest on our piece of white coral1 as you read that each of those little sups on its stem with delicate divisions like the spokes of a wheel has been the home of a separate polyp1 and that from the sea-water each little jelly animal has drunk in carbonate of lime as you drink in sugar dissolved in water1 and then has used it grain by grain to build that delicate cup and add to the coral tree4 ,we cannot stop to examine all about coral now1 we are only learning how to learn1 but surely our specimen is already beginning to grow interesting2 and when you have followed it out into the great ,pacific ,ocean1 where the wild waves dash restlessly against the coral trees1 and have seen these tiny drops of jelly conquering the sea and building huge walls of stone against the rough breakers1 you will hardly rest till you know all their history4 ,look at that curious circular island in the picture1 covered with palm trees2 it has a large smooth lake in the middle1 and the bottom of this lake is covered with blue1 red1 and green jelly animals1 spreading out their feelers in the water and looking like beautiful flowers1 and all round the outside of the island similar animals are to be seen washed by the sea waves4 ,such islands as this have been build entirely by the coral animals1 and the history of the way in which the reefs have sunk gradually down1 as the tiny creatures added to them inch by inch1 is as fascinating as the story of the building of any fairy palace in the days of old4 ,read all this1 and then if you have no coral of your own to examine1 go to the ,british ,museum and see the beautiful specimens in the glass cases there1 and think that they have been built up under the rolling surf by the tiny jelly animals2 and then coral will become a real living thing to you1 and you will love the thoughts it awakens4 ,but people often ask1 what is the use of learning all this8 ,if you do not feel by this time how delightful it is to fill your mind with beautiful pictures of nature1 perhaps it would be useless to say more4 ,but in this age of ours1 when restlessness and love of excitement pervade so many lives1 is it nothing to be taken out of ourselves and made to look at the wonders of nature going on around us8 ,do you never feel tired and out of sorts1 and want to creep away from your companions1 because they are merry and you are not8 ,then is the time to read about the starts1 and how quietly they keep their course from age to age2 or to visit some little flower1 and ask what story it has to tell2 or to watch the clouds1 and try to imagine how the winds drive them across the sky4 ,no person is so independent as he who can find interest in a bare rock1 a drop of water1 the foam of the sea1 the spider on the wall1 the flower underfoot or the starts overhead4 ,and these interests are open to everyone who enters the fairy-land of science4 ,moreover1 we learn from this study to see that there is a law and purpose in everything in the ,universe1 and it makes us patient when we recognize the quiet noiseless working of nature all around us4 ,study light1 and learn how all colour1 beauty1 and life depend on the sun's rays2 note the winds and currents of the air1 regular even in their apparent irregularity1 as they carry heat and moisture all over the world4 ,watch the water flowing in deep quiet streams1 or forming the vast ocean2 and then reflect that every drop is guided by invisible forces working according to fixed laws4 ,see plants springing up under the sunlight1 learn the secrets of plant life1 and how their scents and colours attract the insects4 ,read how insects cannot live without plants1 nor plants without the flitting butterfly or the busy bee4 ,realize that all this is worked by fixed laws1 and that out of it 7even if sometimes in suffering and pain7 springs the wonderful universe around us4 ,and then say1 can you fear for your own little life1 even though it may have its troubles8 ,can you help feeling a part of this guided and governed nature8 or doubt that the power which fixed the laws of the stars and of the tiniest drop of water - that made the plant draw power from the sun1 the tine coral animal its food from the dashing waves2 that adapted the flower to the insect and the insect to the flower - is also moulding your life as part of the great machinery of the universe1 so that you have only to work1 and to wait1 and to love8 ,we are all groping dimly for the ,unseen ,power1 but no one who loves nature and studies it can ever feel alone or unloved in the world4 ,facts1 as mere facts1 are dry and barren1 but nature is full of life and love1 and her calm unswerving rule is tending to some great though hidden purpose4 ,you may call this ,unseen ,power what you will - may lean on it in loving1 trusting faith1 or bend in reverent and silent awe2 but even the little child who lives with nature and gazes on her with open eye1 must rise in some sense or other through nature to nature's ,god4 ,week #c ,lecture ,,ii ,sunbeams and ,how ,they ,work ,who does not love the sunbeams1 and feel brighter and merrier as he watches them playing on the wall1 sparkling like diamonds on the ripples of the sea1 or making bows of coloured light on the waterfall8 ,is not the sunbeam so dear to us that it has become a household word for all that is merry and gay8 and when we want to describe the dearest1 busiest little sprite amongst us1 who wakes a smile on all faces wherever she goes1 do we not call her the sunbeam of the house8 ,and yet how little even the wisest among us know about the nature and work of these bright messengers of the sun as they dart across space6 ,did you ever wake quite early in the morning1 when it was pitch- dark and you could see nothing1 not even your own hand2 and then lie watching as time went on till the light came gradually creeping in at the window8 ,if you have done this you will have noticed that you can at first only just distinguish the dim outline of the furniture2 then you can tell the difference between the white cloth on the table and the dark wardrobe beside it2 then by degrees all the smaller details1 the handles of the drawer1 the pattern on the wall1 and the different colours of all the objects in the room become clearer and clearer till at last you see all distinctly in broad daylight4 ,what has been happening here8 and why have the things in the room become visible by such slow degrees8 ,we say that the sun is rising1 but we know very well that it is not the sun which moves1 but that our earth has been turning slowly round1 and bringing the little spot on which we live face to face with the great fiery ball1 so that his beams can fall upon us4 ,take a small globe1 and stick a piece of black plaster over ,england1 then let a lighted lamp represent the sun1 and turn the globe slowly1 so that the spot creeps round from the dark side away from the lamp1 until it catches1 first the rays which pass along the side of the globe1 then the more direct rays1 and at last stands fully in the blaze of the light4 ,just this was happening to our spot of the world as you lay in bed and saw the light appear2 and we have to learn today what those beams are which fall upon us and what they do for us4 ,first we must learn something about the sun itself1 since it is the starting-place of all the sunbeams4 ,if the sun were a dark mass instead of a fiery one we should have none of these bright cheering messengers1 and though we were turned face to face with him every day we should remain in one cold eternal night4 ,now you will remember we mentioned in the last lecture that it is heat which shakes apart the little atoms of water and makes them gloat up in the air to fall again as rain2 and that if the day is cold they fall as snow1 and all the water is turned into ice4 ,but if the sun were altogether dark1 think how bitterly cold it would be2 far colder than the most wintry weather ever known1 because in the bitterest night some warmth comes out of the earth1 where it has been stored from the sunlight which fell during the day4 ,but if we never received any warmth at all1 no water would ever rise up into the sky1 no rain ever fall1 no rivers flow1 and consequently no plants could grow and no animals live4 ,all water would be in the form of snow and ice1 and the earth would be one great frozen mass with nothing moving upon it4 ,so you see it becomes very interesting for us to learn what the sun is1 and how he sends us his beams4 ,how far away from us do you think he is8 ,on a fine summer's day when we can see him clearly1 it looks as if we had only to get into a balloon and reach him as he sits in the sky1 and yet we know roughly that he is more than ninety-one millions of miles distant from our earth4 ,these figures are so enormous that you cannot really grasp them4 ,but imagine yourself in an express train1 travelling at the tremendous rate of sixty miles an hour and never stopping4 ,at that rate1 if you wished to arrive at the sun today you would have been obliged to start #aga years ago4 ,that is1 you must have set off in the early part of the reign of ,queen ,anne1 and you must have gone on1 never1 never resting1 through the reigns of ,george ,i1 ,george ii1 and the long reign of ,george ,,iii1 then through those of ,george ,,iv1 ,william ,,iv1 and ,victoria1 whirling on day and night at express speed1 and at last1 today1 you would have reached the sun6 ,and when you arrived there1 how large do you think you would find him to be8 ,anaxagoras1 a learned ,greek1 was laughed at by all his fellow ,greeks because he said that the sun was as large as the ,peloponne-sus1 that is about the size of ,middlesex4 ,how astonished they would have been if they could have known that not only is he bigger than the whole of ,greece1 but more than a million times bigger than the whole world6 ,our world itself is a very large place1 so large that our own country looks only like a tiny speck upon it1 and an express train would take nearly a month to travel round it4 ,yet even our whole globe is nothing in size compared to the sun1 for it only measures #hjjj miles across1 while the sun measures more the #heb1jjj4 ,imagine for a moment that you could cut the sun and the earth each in half as you would cut an apple2 then if you were to lay the flat side of the half-earth on the flat side of the half sun it would take #ajf such earths to stretch across the face of the sun4 ,one of these #ajf round spots on the diagram represents the size which our earth would look if placed on the sun2 and they are so tiny compared to him that they look only like a string of minute beads stretched across his face4 ,only think1 then1 how many of these minute dots would be required to fill the whole of the inside of ,fig4 #d1 if it were a globe4 ,one of the best ways to form an idea of the whole size of the sun is to imagine it to be hollow1 like an air-ball1 and then see how many earths it would take to fill it4 ,you would hardly believe that it would take one million1 three hundred and thirty-one thousand globes the size of our world squeezed together4 ,just think1 if a huge giant could travel all over the universe and gather worlds1 all as big as ours1 and were to make first a heap of merely ten such worlds1 how huge it would be6 ,then he must have a hundred such heaps of ten to make a thousand world2 and then he must collect again a thousand times that thousand to make a million1 and when he had stuffed them all into the sun-ball he would still have only filled three-quarters of it6 ,after hearing this you will not be astonished that such a monster should give out an enormous quantity of light and heat2 so enormous that it is almost impossible to form any idea of it4 ,sir ,john ,herschel has1 indeed1 tried to picture it for us4 ,he found that a ball of lime with a flame of oxygen and hydrogen playing round it 7such as we use in magic lanterns and call oxy- hydrogen light7 becomes so violently hot that it gives the most brilliant artificial light we can get - such that you cannot put your eye near it without injury4 ,yet if you wanted to have a light as strong as that of our sun1 it would not be enough to make such a lime-ball as big as the sun is4 ,no1 you must make it as big as #adf suns1 or more than #adf1jjj1jjj times as big as our earth1 in order to get the right amount of light4 ,then you would have a tolerably good artificial sun2 for we know that the body of the sun gives out an intense white light1 just as the lime- ball does1 and that 1 like it1 it has an atmosphere of glowing gases round it4 ,but perhaps we get the best idea of the mighty heat and light of the sun by remembering how few of the rays which dart out on all sides from this fiery ball can reach our tiny globe1 and yet how powerful they are4 ,look at the globe of a lamp in the middle of the room1 and see how its light pours out on all sides and into every corner2 then take a grain of mustard-seed1 which will very well represent the comparative size of our earth1 and hold it up at a distance from the lamp4 ,how very few of all those rays which are filling the room fall on the little mustard-seed1 and just so few does our earth catch of the rays which dart out from the sun4 ,and yet this small quantity 7#a_/bjjj-millionth part of the whole7 does nearly all the work of our world4 7,these and the preceding numerical statements will be found worked out in ,sir ,j4 ,herschel's ',familiar ,lectures on ,scientific ,subjects1' #ahfh1 from which many of the facts in the first part of the lecture are taken47 ,in order to see how powerful the sun's rays are1 you have only to take a magnifying glass and gather them to a point on a piece of brown paper1 for they will set the paper alight4 ,sir ,john ,herschel tells us that at the ,cape of ,good ,hope the heat was even so great that he cooked a beefsteak and roasted some eggs by merely putting them in the sun1 in a box with a glass lid6 ,indeed1 just as we should all be frozen to death if the sun were sold1 so we should all be burnt up with intolerable heat if his fierce rays fell with all their might upon us4 ,but we have an invisible veil protecting us1 made - of what do you think8 ,of those tiny particles of water which the sunbeams draw up and scatter in the air1 and which1 as we shall see in ,lecture ,,iv1 cut off part of the intense heat and make the air cool and pleasant for us4 ,week #d ,we have now learnt something of the distance1 the size1 the light1 and the heat of the sun - the great source of the sunbeams4 ,but we are as yet no nearer the answer to the question1 ,what is a sunbeam8 how does the sun touch our earth8 ,now suppose ,i with to touch you from this platform where ,i stand1 ,i can do it in two ways4 ,firstly1 ,i can throw something at you and hit you - in this case a thing will have passed across the space from me to you4 ,or1 secondly1 if ,i could make a violent movement so as to shake the floor of the room1 you would feel a quivering motion2 and so ,i should touch you across the whole distance of the room4 ,but in this case no thing would have passed from me to you but a movement or wave1 which passed along the boards of the floor4 ,again1 if ,i speak to you1 how does the sound reach you ear8 ,not by anything being thrown from my mouth to your ear1 but by the motion of the air4 ,when ,i speak ,i agitate the air near my mouth1 and that makes a wave in the air beyond1 and that one1 another1 and another 7as we shall see more fully in ,lecture ,,vi7 till the last wave hits the drum of your ear4 ,thus we see there are two ways of touching anything at a distance2 #ast1 by throwing some thing at it and hitting it2 #bnd1 by sending a movement of wave across to it1 as in the case of the quivering boards and the air4 ,now the great natural philosopher ,newton thought that the sun touched us in the first of these ways1 and that sunbeams were made of very minute atoms of matter thrown out by the sun1 and making a perpetual cannonade on our eyes4 ,it is easy to understand that this would make us see light and feel heat1 just as a blow in the eye makes us see starts1 or on the body makes it feel hot3 and for a long time this explanation was supposed to be the true one4 ,but we know now that there are many facts which cannot be explained on this theory1 though we cannot go into them here4 ,what we will do1 is to try and understand what now seems to be the true explanation of the sunbeam4 ,about the same time that ,newton wrote1 a ,dutchman1 named ,huyghens1 suggested that light comes from the sun in tiny waves1 travelling across space much in the same way as ripples travel across a pond4 ,the only difficulty was to explain in what substance these waves could be travelling3 not through water1 for we know that there is no water in space - nor through air1 for the air stops at a comparatively short distance from our earth4 ,there must then be something filling all space between us and the sun1 finer than either water or air4 ,and now ,i must ask you to use all you imagination1 for ,i want you to picture to yourselves something quite as invisible as the ,emperor's new clothes in ,andersen's fairy-tale1 only with this difference1 that our invisible something is very active2 and though we can neither see it nor touch it we know it by its effects4 ,you must imagine a fine substance filling all space between us and the sun and the starts4 ,a substance so very delicate and subtle1 that not only is it invisible1 but it can pass through solid bodies such as glass1 ice1 or even wood or brick walls4 ,this substance we call ether4 ,i cannot give you here the reasons why we must assume that it is throughout all space2 you must take this on the word of such men as ,sir ,john ,herschel or ,professor ,clerk-,maxwell1 until you can study the question for yourselves4 ,now if you can imagine this ether filling every corner of space1 so that it is everywhere and passes through everything1 ask yourselves1 what must happen when a great commotion is going on in one of the large bodies which float in it8 ,when the atoms of the gases round the sun are clashing violently together to make all its light and heat1 do you not think they must shake this ether all around them8 ,and then1 since the ether stretches on all sides from the sun to our earth and all other planets1 must not this quivering travel to us1 just as the quivering of the boards would from me to you8 ,take a basin of water to represent the ether1 and take a piece of potassium like that which we used in our last lecture1 and hold it with a pair of nippers in the middle of the water4 ,you will see that as the potassium hisses and the flame burns round it1 they will make waves which will travel all over the water to the edge of the basin11 and you can imagine how in the same way waves travel over the ether from the sun to us4 ,straight away from the sun on all sides1 never stopping1 never resting1 but chasing after each other with marvellous quickness1 these tiny waves travel out into space by night and by day4 ,when our spot of the earth where ,england lies is turned away from them and they cannot touch us1 then it is night for us1 but directly ,england is turned so as to face the sun1 then they strike on the land1 and the water1 and warm it2 or upon our eyes1 making the nerves quiver so that we see light4 ,look up at the sun and picture to yourself that instead of one great blow from a fist causing you to see starts for a moment1 millions of tiny blows from these sun-waves are striking every instant on you eye2 then you will easily understand that his would cause you to see a constant blaze of light4 ,but when the sun is away1 if the night is clear we have light from the starts4 ,do these then too make waves all across the enormous distance between them and us8 ,certainly they do1 for they too are suns like our own1 only they are so far off that the waves they send are more feeble1 and so we only notice them when the sun's stronger waves are away4 ,but perhaps you will ask1 if no one has ever seen these waves not the ether in which they are made1 what right have we to say they are there8 ,strange as it may seem1 though we cannot see them we have measured them and know how large they are1 and how many can go into an inch of space4 ,for as these tiny waves are running on straight forward through the room1 if we put something in their way1 they will have to run round it2 and if you let in a very narrow ray of light through a shutter and put an upright wire in the sunbeam1 you actually make the waves run round the wire just as water runs round a post in a river2 and they meet behind the wire1 just as the water meets in a ,v shape behind the post4 ,now when they meet1 they run up against each other1 and here it is we catch them4 ,fir if they meet comfortably1 both rising up in a good wave1 they run on together and make a bright line of light2 but if they meet higgledy-piggledy1 one up and the other down1 all in confusion1 they stop each other1 and then there is no light but a line of darkness4 ,and so behind your piece of wire you can catch the waves on a piece of paper1 and you will find they make dark and light lines one side by side with the other1 and by means of these bands it is possible to find out how large the waves must be4 ,this question is too difficult for us to work it out here1 but you can see that large waves will make broader light and dark bands than small ones will1 and that in this way the size of the waves may be measured4 ,and now how large do you think they turn out to be8 so very1 very tiny that about fifty thousand waves are contained in a single inch of space6 ,i have drawn on the board the length of an inch1 and now ,i will measure the same space in the air between my finger and thumb4 ,within this space at this moment there are fifty thousand tiny waves moving up and down4 ,i promised you we would find in science things as wonderful as in fairy tales4 ,are not these tiny invisible messengers coming incessantly from the sun as wonderful as any fairies8 and still more so when1 as we shall see presently1 they are doing nearly all the work of our world4 ,we must next try to realize how fast these waves travel4 ,you will remember that an express train would take #aga years to reach us from the sun2 and even a cannon-ball would take from ten to thirteen years to come that distance4 ,well1 these tiny waves take only seven minutes and a half to come the whole #ia millions of miles4 ,the waves which are hitting your eye at this moment are caused by a movement which began at the sun only #g #a_/b minutes ago4 ,and remember1 this movement is going on incessantly1 and these waves are always following one after the other so rapidly that they keep up a perpetual cannonade upon the pupil of your eye4 ,so fast do they come that about #fjh billion waves enter your eye in one single second499 ,i do not ask you to remember these figures2 ,i only ask you to try and picture to yourselves these infinitely tiny and active invisible messengers from the sun1 and to acknowledge that light is a fairy thing4 799,light travels at the rate of #aij1jjj miles1 or #ab1afe1abj1jjj inches in a second4 ,taking the average number of wave-lengths in an inch at #ej1jjj1 then #ab1afe1abj1jjj ,x #ej1jjj #fjh1bef1jjj1jjj1jjj47 ,but we do not yet know all about our sunbeams4 ,see1 ,i have here a piece of glass with three sides1 called a prism4 ,if ,i put it in the sunlight which is streaming through the window1 what happens8 ,look6 on the table there is a line of beautiful colours4 ,i can make it long or short1 as ,i turn the prism1 but the colours always remain arranged in the same way4 ,here at my left hand is the red1 beyond it orange1 then yellow1 green1 blue1 indigo or deep blue1 and violet1 shading one into the other all along the line4 ,we have all seen these colours dancing on the wall when the sun has been shining brightly on the cut-glass pendants of the chandelier1 and you may see them still more distinctly if you let a ray of light into a darkened room1 and pass it through the prism as in the diagram 7,fig4 #g74 ,what are these colours8 ,do they come from the glass8 ,no2 for you will remember to have seen them in the rainbow1 and in the soap- bubble1 and even in a drop of dew or the scum on the top of a pond4 ,this beautiful coloured line is only our sunbeam again1 which has been split up into many colours by passing through the glass1 as it is in the rain-drops of the rainbow and the bubbles of the scum of the pond4 ,week #e ,till now we have talked of the sunbeam as if it were made of only one set of waves of different sizes1 all travelling along together from the sun4 ,these various waves have been measured1 and we know that the waves which make up red light are larger and more lazy than those which make violet light1 so that there are only thirty-nine thousand red waves in an inch1 while there are fifty-seven thousand violet waves in the same space4 ,how is it then1 that if all these different waves making different colours1 hit on our eye1 they do not always make us see coloured light8 ,because1 unless they are interfered with1 they all travel along together1 and you know that all colours1 mixed together in proper proportion1 make white4 ,i have here a round piece of cardboard1 painted with the seven colours in succession several times over4 ,when it is still you can distinguish them all apart1 but when ,i whirl it quickly round - see6 - the cardboard looks quite white1 because we see them all so instantaneously that they are mingled together4 ,in the same way light looks white to you1 because all the different coloured waves strike on your eye at once4 ,you can easily make on of these card for yourselves only the white will always look dirty1 because you cannot get the colours pure4 ,now1 when the light passes through the three-sided glass or prism1 the waves are spread out1 and the slow1 heavy1 red waves lag behind and remain at the lower end ,r of the coloured line on the wall 7,fig4 #g71 while the rapid little violet waves are bent more out of their road and run to ,v at the farther end of the line2 and the orange1 yellow1 green1 blue1 and indigo arrange themselves between1 according to the size of their waves4 ,and now you are very likely eager to ask why the quick waves should make us see one colour1 and the slow waves another4 ,this is a very difficult question1 for we have a great deal still to learn about the effect of light on the eye4 ,but you can easily imagine that colour is to our eye much the same as music is to our ear4 ,you know we can distinguish different notes when the air-waves play slowly or quickly upon the drum of the ear 7as we shall see in ,lecture ,,vi7 and somewhat in the same way the tiny waves of the ether play on the retina or curtain at the back of our eye1 and make the nerves carry different messages to the brain3 and the colour we see depends upon the number of waves which play upon the retina in a second4 ,do you think we have now rightly answered the question - ,what is a sunbeam8 ,we have seen that it is really a succession of tiny rapid waves1 travelling from the sun to us across the invisible substance we call ether1 and keeping up a constant cannonade upon everything which comes in their way4 ,we have also seen that1 tiny as these waves are1 they can still vary in size1 so that one single sunbeam is made up of myriads of different-sized waves1 which travel all together and make us see white light2 unless for some reason they are scattered apart1 so that we see them separately as red1 green1 blue1 or yellow4 ,how they are scattered1 and many other secrets of the sun-waves1 we cannot stop to consider not1 but must pass on to ask - ,what work do the sunbeams do for us8 ,they do two things - they give us light and heat4 ,it is by means of them alone that we see anything4 ,when the room was dark you could not distinguish the table1 the chairs1 or even the walls of the room4 ,why8 ,because they had no light-waves to send to your eye4 ,but as the sunbeams began to pour in at the window1 the waves played upon the things in the room1 and when they hit them they bounded off them back to your eye1 as a wave of the sea bounds back from a rock and strikes against a passing boat4 ,then1 when they fell upon your eye1 they entered it and excited the retina and the nerves1 and the image of the chair or the table was carried to your brain4 ,look around at all the things in this room4 ,is it not strange to think that each one of them is sending these invisible messengers straight to your eye as you look at it2 and that you see me1 and distinguish me from the table1 entirely by the kind of waves we each send to you8 ,some substances send back hardly any waves of light1 but let them all pass through them1 and thus we cannot see them4 ,a pane of clear glass1 for instance1 lets nearly all the light-waves pass through it1 and therefore you often cannot see that the glass is there1 because no light-messengers come back to you from it4 ,thus people have sometimes walked up against a glass door and broken it1 not seeing it was there4 ,those substances are transparent which1 for some reason unknown to us1 allow the ether waves to pass through them without shaking the atoms of which the substance is made4 ,in clear glass1 for example1 all the light- waves pass through without affecting the substance of the glass2 while in a white wall the larger part of the rays are reflected back to your eye1 and those which pass into the wall1 by giving motion to its atoms lose their own vibrations4 ,into polished shining metal the waves hardly enter at all1 but are thrown back from the surface2 and so a steel knife or a silver spoon are very bright1 and are clearly seen4 ,quicksilver is put at the back of looking-glasses because it reflects so many waves4 ,it not only sends back those which come from the sun1 but those1 too1 which come from your face4 ,so1 when you see yourself in a looking-glass1 the sun-waves have first played on your face and bounded off from it to the looking-glass2 then1 when they strike the looking-glass1 they are thrown back again on to the retina of your eye1 and you see your own face by means of the very waves you threw off from it an instant before4 ,but the reflected light-waves do more for us than this4 ,they not only make us see things1 but they make us see them in different colours4 ,what1 you will ask1 is this too the work of the sunbeams8 ,certainly2 for if the colour we see depends on the size of the waves which come back to us1 then we must see things coloured differently according to the waves they send back4 ,for instance1 imagine a sunbeam playing on a leaf3 part of its waves bound straight back from it to our eye and make us see the surface of the leaf1 but the rest go right into the leaf itself1 and there some of them are used up and kept prisoners4 ,the red1 orange1 yellow1 blue1 and violet waves are all useful to the leaf1 and it does not let them go again4 ,but it cannot absorb the green waves1 and so it throws them back1 and they travel to your eye and make you see a green colour4 ,so when you say a leaf is green1 you mean that the leaf does not want the green waves of the sunbeam1 but sends them back to you4 ,in the same way the scarlet geranium rejects the red waves2 this table sends back brown waves2 a white tablecloth sends back nearly the whole of the waves1 and a black coat scarcely any4 ,this is why1 when there is very little light in the room1 you can see a white tablecloth while you would not be able to distinguish a black object1 because the few faint rays that are there1 are all sent back to you from a white surface4 ,is it not curious to think that there is really no such thing as colour in the leaf1 the table1 the coat1 or the geranium flower1 but we see them of different colours because1 for some reason1 they send back only certain coloured waves to our eye8 ,wherever you look1 then1 and whatever you see1 all the beautiful tints1 colours1 lights1 and shades around you are the work of the tiny sun-waves4 ,again1 light does a great deal of work when it falls upon plants4 ,those rays of light which are caught by the leaf are by no means idle2 we shall see in ,lecture ,,vii that the leaf uses them to digest its food and make the sap on which the plant feeds4 ,week #f ,we all know that a plant becomes pale and sickly if it has not sunlight1 and the reason is1 that without these light-waves it cannot get food out of the air1 nor make the sap and juices which it needs4 ,when you look at plants and trees growing in the beautiful meadows2 at the fields of corn1 and at the lovely landscape1 you are looking on the work of the tiny waves of light1 which never rest all through the day in helping to give life to every green thing that grows4 ,so far we have spoken only of light2 but hold your hand in the sun and feel the heat of the sunbeams1 and then consider if the waves of heat do not do work also4 ,there are many waves in a sunbeam which move too slowly to make us see light when they hit our eye1 but we can feel them as heat1 though we cannot see them as light4 ,the simplest way of feeling heat-waves is to hold a warm iron near your face4 ,you know that no light comes from it1 yet you can feel the heat-waves beating violently against your face and scorching it4 ,now there are many of these dark heat- rays in a sunbeam1 and it is they which do most of the work in the world4 ,in the first place1 as they come quivering to the earth1 it is they which shake the water-drops apart1 so that these are carried up in the air1 as we shall see in the next lecture4 ,and then remember1 it is these drops1 falling again as rain1 which make the rivers and all the moving water on the earth4 ,so also it is the heat-waves which make the air hot and light1 and so cause it to rise and make winds and air-currents1 and these again give rise to ocean-currents4 ,it is these dark rays1 again1 which strike upon the land and give it the warmth which enables plants to grow4 ,it is they also which keep up the warmth in our own bodies1 both by coming to us directly from the sun1 and also in a very roundabout way through plants4 ,you will remember that plants use up rays of light and heat in growing2 then either we eat the plants1 or animals eat the plants and we eat the animals2 and when we digest the food1 that heat comes back in our bodies1 which the plants first took from the sunbeam4 ,breathe upon your hand1 and feel how hot your breath is2 well1 that heat which you feel1 was once in a sunbeam1 and has travelled from it through the food you have eaten1 and has now been at work keeping up the heat of your body4 ,but there is still another way in which these plants may give out the heat-waves they have imprisoned4 ,you will remember how we learnt in the first lecture that coal is made of plants1 and that the heat they give out is the heat these plants once took in4 ,think how much work is done by burning coals4 ,not only are our houses warmed by coal fires and lighted by coal gas1 but our steam-engines and machinery work entirely by water which has been turned into steam by the heat of coal and coke fire2 and our steamboats travel all over the world by means of the same power4 ,in the same way the oil of our lamps comes either from olives1 which grow on trees2 or from coal and the remains of plants and animals in the earth4 ,even our tallow candles are made of mutton fat1 and sheep eat grass2 as so1 turn which way we will1 we find that the light and heat on our earth1 whether it comes from fires1 or candles1 or lamps1 or gas1 and whether it moves machinery1 or drives a train1 or propels a ship1 is equally the work of the invisible waves of ether coming from the sun1 which make what we call a sunbeam4 ,lastly1 there are still some hidden waves which we have not yet mentioned1 which are not useful to us either as light or heat1 and yet they are not idle4 ,before ,i began this lecture1 ,i put a piece of paper1 which had been dipped in nitrate of silver1 under a piece of glass2 and between it and the glass ,i put a piece of lace4 ,look what the sun has been doing while ,i have been speaking4 ,it has been breaking up the nitrate of silver on the paper and turning it into a deep brown substance2 only where the threads of the lace were1 and the sun could not touch the nitrate of silver1 there the paper has remained light-coloured1 and by this means ,i have a beautiful impression of the lace on the paper4 ,i will now dip the impression into water in which some hyposulphite of soda is dissolved1 and this will fix the picture1 that is1 prevent the sun acting upon it any more2 then the picture will remain distinct1 and ,i can pass it round to you all4 ,here1 again1 invisible waves have been at work1 and this time neither as light nor as heat1 but as chemical agents1 and it is these waves which give us all our beautiful photographs4 ,in any toyshop you can buy this prepared paper1 and set the chemical waves at work to make pictures4 ,only you must remember to fix it in the solution afterwards1 otherwise the chemical rays will go on working after you have taken the lace away1 and all the paper will become brown and your picture will disappear4 ,and now1 tell me1 may we not honestly say1 that the invisible waves which make our sunbeams1 are wonderful fairy messengers as they travel eternally and unceasingly across space1 never resting1 never tiring in doing the work of our world8 ,little as we have been able to learn about them in one short hour1 do they not seem to you worth studying and worth thinking about1 as we look at the beautiful results of their work8 ,the ancient ,greeks worshipped the sun1 and condemned to death one of their greatest philosophers1 named ,anaxagoras1 because he denied that it was a god4 ,we can scarcely wonder at this when we see what the sun does for our world2 but we know that it is a huge globe made of gases and fiery matter and not a god4 ,we are grateful for the sun instead of to him1 and surely we shall look at him with new interest1 now that we can picture his tiny messengers1 the sunbeams1 flitting over all space1 falling upon our earth1 giving us light to see with1 and beautiful colours to enjoy1 warming the air and the earth1 making the refreshing rain1 and1 in a word1 filling the world with life and gladness4 ,week #g ,,lecture ,,iii ,the ,aerial ,ocean in ,which ,we ,live ,did you ever sit on the bank of a river in some quiet spot where the water was deep and clear1 and watch the fishes swimming lazily along8 ,when ,i was a child this was one of my favourite occupations in the summertime on the banks of the ,thames1 and there was one question which often puzzled me greatly1 as ,i watched the minnows and gudgeon gliding along through the water4 ,why should fishes live in something and be often buffeted about by waves and currents1 while ,i and others lived on the top of the earth and not in anything8 ,i do not remember ever asking anyone about this2 and if ,i had1 in those days people did not pay much attention to children's questions1 and probably nobody would have told me1 what ,i now tell you1 that we do live in something quite as real and often quite as rough and stormy as the water in which the fishes swim4 ,the something in which we live is air1 and the reason that we do not perceive it1 is that we are in it1 and that it is a gas1 and invisible to us2 while we are above the water in which the fishes live1 and it is a liquid which our eyes can perceive4 ,but let us suppose for a moment that a being1 whose eyes were so made that he could see gases as we see liquids1 was looking down from a distance upon our earth4 ,he would see an ocean of air1 or aerial ocean1 all round the globe1 with birds floating about in it1 and people walking along the bottom1 just as we see fish gliding along the bottom of a river4 ,it is true1 he would never see even the birds come near to the surface1 for the highest- flying bird1 the condor1 never soars more than five miles from the ground1 and our atmosphere1 as we shall see1 is at least #ajj miles high4 ,so he would call us all deep-air creatures1 just as we talk of deep-sea animals2 and if we can imagine that he fished in this air-ocean1 and could pull one of us out of it into space1 he would find that we should gasp and die just as fishes do when pulled out of the water4 ,he would also observe very curious things going on in our air- ocean2 he would see large streams and currents of air1 which we call winds1 and which would appear to him as ocean-currents do to us1 while near down to the earth he would see thick mists forming and then disappearing again1 and these would be our clouds4 ,from them he would see rain1 hail and snow falling to the earth1 and from time to time bright flashes would shoot across the air- ocean1 which would be our lightning4 ,nay even the brilliant rainbow1 the northern aurora borealis1 and the falling stars1 which seem to us so high up in space1 would be seen by him near to our earth1 and all within the aerial ocean4 ,but as we know of no such being living in space1 who can tell us what takes place in our invisible air1 and we cannot see it ourselves1 we must try by experiments to see it with our imagination1 though we cannot with our eyes4 ,first1 then1 can we discover what air is8 ,at one time it was thought that it was a simple gas and could not be separated into more than one kind4 ,but we are now going to make an experiment by which it has been shown that air is made of two gases mingled together1 and that one of these gases1 called oxygen1 is used up when anything burns1 while the other nitrogen is not used1 and only serves to dilute the minute atoms of oxygen4 ,i have here a glass bell-jar1 with a cork fixed tightly in the neck1 and ,i place the jar over a pan of water1 while on the water floats a plate with a small piece of phosphorus upon it4 ,you will see that by putting the bell-jar over the water1 ,i have shut in a certain quantity of air1 and my object now is to use up the oxygen out of this air and leave only nitrogen behind4 ,to do this ,i must light the piece of phosphorus1 for you will remember it is in burning that oxygen is used up4 ,i will take the cork out1 light the phosphorus1 and cork up the jar again4 ,see6 as the phosphorus burns white fumes fill the jar4 ,these fumes are phosphoric acid which is a substance made of phosphorous and the oxygen of the air together4 ,now1 phosphoric acid melts in water just as sugar does1 and in a few minutes these fumes will disappear4 ,they are beginning to melt already1 and the water from the pan is rising up in the bell-jar4 ,why is this8 ,consider for a moment what we have done4 ,first1 the jar was full of air1 that is1 of mixed oxygen and nitrogen2 then the phosphorus used up the oxygen making white fumes2 afterwards1 the water sucked up these fumes2 and so1 in the jar now nitrogen is the only gas left1 and the water has risen up to fill all the rest of the space that was once taken up with oxygen4 ,we can easily prove that there is no oxygen now in the jar4 ,i take out the cork and let a lighted taper down into the gas4 ,if there were any oxygen the taper would burn1 but you see it goes out directly proving that all the oxygen has been used up by the phosphorous4 ,when this experiment is made very accurately1 we find that for every pint of oxygen in air there are four pints of nitrogen1 so that the active oxygen-atoms are scattered about1 floating in the sleepy1 inactive nitrogen4 ,it is these oxygen-atoms which we use up when we breathe4 ,if ,i had put a mouse under the bell-jar1 instead of the phosphorus1 the water would have risen just the same1 because the mouse would have breathed in the oxygen and used it up in its body1 joining it to carbon and making a bad gas1 carbonic acid1 which would also melt in the water1 and when all the oxygen was used1 the mouse would have died4 ,do you see now how foolish it is to live in rooms that are closely shut up1 or to hide your head under the bedclothes when you sleep8 ,you use up all the oxygen-atoms1 and then there are none left for you to breathe2 and besides this1 you send out of your mouth bad fumes1 though you cannot see them1 and these1 when you breathe them in again1 poison you and make you ill4 ,perhaps you will say1 ,if oxygen is so useful1 why is not the air made entirely of it8 ,but think for a moment4 ,if there was such an immense quantity of oxygen1 how fearfully fast everything would burn6 ,our bodies would soon rise above fever heat from the quantity of oxygen we should take in1 and all fires and lights would burn furiously4 ,in fact1 a flame once lighted would spread so rapidly that no power on earth could stop it1 and everything would be destroyed4 ,so the lazy nitrogen is very useful in keeping the oxygen-atoms apart2 and we have time1 even when a fire is very large and powerful1 to put it out before it has drawn in more and more oxygen from the surrounding air4 ,often1 if you can shut a fire into a closed space1 as in a closely-shut room or the hold of a ship1 it will go out1 because it has used up all the oxygen in the air4 ,so1 you see1 we shall be right in picturing this invisible air all around us as a mixture of two gases4 ,but when we examine ordinary air very carefully1 we find small quantities of other gases in it1 besides oxygen and nitrogen4 ,first1 there is carbonic acid gas4 ,this is the bad gas which we give out of our mouths after we have burnt up the oxygen with the carbon of our bodies inside our lungs2 and this carbonic acid is also given out from everything that burns4 ,if only animals lived in the world1 this gas would soon poison the air2 but plants get hold of it1 and in the sunshine they break it up again1 as we shall see in ,lecture ,,vii1 and use up the carbon1 throwing the oxygen back into the air for us to use4 ,secondly1 there are very small quantities of ammonia1 or the gas which almost chokes you in smelling-salts1 and which1 when liquid is commonly called spirits of hartshorn4 ,this ammonia is useful to plants1 as we shall see by and by4 ,lastly1 there is a great deal of water in the air1 floating about as invisible vapour or water-dust1 and this we shall speak of in the next lecture4 ,still1 all these gases and vapours in the atmosphere are in very small quantities1 and the bulk of the air is composed of oxygen and nitrogen4 ,having now learned what air is1 the next question which presents itself is1 ,why does it stay round our earth8 ,you will remember we saw in the first lecture1 that all the little atoms of a gas are trying to fly away from each other1 so that if ,i turn on this gas-jet the atoms soon leave it1 and reach you at the farther end of the room1 and you can smell the gas4 ,why1 then1 do not all the atoms of oxygen and nitrogen fly away from our earth into space1 and leave us without any air8 ,ah6 here you must look for another of our invisible forces4 ,have you forgotten our giant force1 gravitation1 which draws things together from a distance8 ,this force draws together the earth and the atoms of oxygen and nitrogen2 and as the earth is very big and heavy1 and the atoms of air are light and easily moved1 they are drawn down to the earth and held there by gravitation4 ,but for all that1 the atmosphere does not leave off trying to fly away2 it is always pressing upwards and outwards with all its might1 while the earth is doing its best to hold it down4 ,the effect of this is1 that near the earth1 where the pull downward is very strong1 the air-atoms are drawn very closely together1 because gravitation gets the best of the struggle4 ,but as we get farther and farther from the earth1 the pull downward becomes weaker1 and then the air-atoms spring farther apart1 and the air becomes thinner4 ,suppose that the lines in this diagram represent layers of air4 ,near the earth we have to represent them as lying closely together1 but as they recede from the earth they are also farther apart4 ,but the chief reason why the air is thicker or denser nearer the earth1 is because the upper layers press it down4 ,if you have a heap of papers lying one on the top of the other1 you know that those at the bottom of the heap will be more closely pressed together than those above1 and just the same is the case with the atoms of the air4 ,only there is this difference1 if the papers have lain for some time1 when you take the top ones off1 the under ones remain close together4 ,but it is not so with the air1 because air is elastic1 and the atoms are always trying to fly apart1 so that directly you take away the pressure they spring up again as far as they can4 ,week #h ,i have here an ordinary pop-gun4 ,if ,i push the cork in very tight1 and then force the piston slowly inwards1 ,i can compress the air a good deal4 ,now ,i am forcing the atoms nearer and nearer together1 but at last they rebel so strongly against being more crowded that the cork cannot resist their pressure4 ,out it flies1 and the atoms spread themselves out comfortably again in the air all around them4 ,now1 just as ,i pressed the air together in the pop-gun1 so the atmosphere high up above the earth presses on the air below and keeps the atoms closely packed together4 ,and in this case the atoms cannot force back the air above them as they did the cork in the pop-gun2 they are obliged to submit to be pressed together4 ,even a short distance from the earth1 however1 at the top of a high mountain1 the air becomes lighter1 because it has less weight of atmosphere above it1 and people who go up in balloons often have great difficulty in breathing1 because the air is so thin and light4 ,in #ahjd a ,frenchman1 named ,gay-,lussac1 went up four miles and a half in a balloon1 and brought down some air2 and he found that it was much less heavy than the same quantity of air taken close down to the earth1 showing that it was much thinner1 or rarer1 as it is called299 and when1 in #ahfb1 ,mr4 ,glaisher and ,mr4 ,coxwell went up five miles and a half1 ,mr4 ,glaisher's veins began to swell1 and his head grew dizzy1 and he fainted4 ,the air was too thin for him to breathe enough in at a time1 and it did not press heavily enough on the drums of his ears and the veins of his body4 ,he would have died if ,mr4 ,coxwell had not quickly let off some of the gas in the balloon1 so that it sank down into denser air4 799#ajj cubic inches near the earth weighed #ca grains1 while the same quantity taken at four and a half miles up in the air weighed only #ab grains1 or two- fifths of the weight47 ,and now comes another very interesting question4 ,if the air gets less and less dense as it is farther from the earth1 where does it stop altogether8 ,we cannot go up to find out1 because we should die long before we reached the limit2 and for a long time we had to guess about how high the atmosphere probably was1 and it was generally supposed not to be more than fifty miles4 ,but lately1 some curious bodies1 which we should have never suspected would be useful to us in this way1 have let us into the secret of the height of the atmosphere4 ,these bodies are the meteors1 or falling stars4 ,most people1 at one time or another1 have seen what looks like a star shoot right across the sky1 and disappear4 ,on a clear starlight night you may often see one or more of these bright lights flash through the air2 for one falls on an average in every twenty minutes1 and on the nights of ,august #ith and ,november #acth there are numbers in one part of the sky4 ,these bodies are not really stars2 they are simply stones or lumps of metal flying through the air1 and taking fire by clashing against the atoms of oxygen in it4 ,there are great numbers of these masses moving round and round the sun1 and when our earth comes across their path1 as it does especially in ,august and ,november1 they dash with such tremendous force through the atmosphere that they grow white-hot1 and give out light1 and then disappear1 melted into vapour4 ,every now and then one falls to the earth before it is all melted away1 and thus we learn that these stones contain tin1 iron1 sulphur1 phosphorus1 and other substances4 ,it is while these bodies are burning that they look to us like falling stars1 and when we see them we know that hey must be dashing against our atmosphere4 ,now if two people stand a certain known distance1 say fifty miles1 apart on the earth and observe these meteors and the direction in which they each see them fall1 they can calculate 7by means of the angle between the two directions7 how high they are above them when they first see them1 and at that moment they must have struck against the atmosphere1 and even travelled some way through it1 to become white-hot4 ,in this way we have learnt that meteors burst into light at least #ajj miles above the surface of the earth1 and so the atmosphere must be more than #ajj miles high4 ,our next question is as to the weight of our aerial ocean4 ,you will easily understand that all this air weighing down upon the earth must be very heavy1 even though it grows lighter as it ascends4 ,the atmosphere does1 in fact1 weigh down upon land at the level of the sea as much as if a #ae-pound weight were put upon every square inch of land4 ,this little piece of linen paper1 which ,i am holding up1 measures exactly a square inch1 and as it lies on the table1 it is bearing a weight of #ae lbs4 on its surface4 ,but how1 then1 comes it that ,i can lift it so easily8 ,why am ,i not conscious of the weight8 ,to understand this you must give all your attention1 for it is important and at first not very easy to grasp4 you must remember1 in the first place1 that the air is heavy because it is attracted to the earth1 and in the second place1 that since air is elastic all the atoms of it are pushing upwards against this gravitation4 ,and so1 at any point in air1 as for instance the place where the paper now is as ,i hold it up1 ,i feel no pressure because exactly as much as gravitation is pulling the air down1 so much elasticity is resisting and pushing it up4 ,so the pressure is equal upwards1 downwards1 and on all sides1 and ,i can move the paper with equal ease any way4 ,even if ,i lay the paper on the table this is still true1 because there is always some air under it4 ,if1 however1 ,i could get the air quite away from one side of the paper1 then the pressure on the other side would show itself4 ,i can do this by simply wetting the paper and letting it fall on the table1 and the water will prevent any air from getting under it4 ,now see6 if ,i try to lift it by the thread in the middle1 ,i have great difficulty1 because the whole #ae pounds' weight of the atmosphere is pressing it down4 ,a still better way of making the experiment is with a piece of leather1 such as the boys often amuse themselves with in the streets4 ,this piece of leather has been well soaked4 ,i drop it on the floor and see6 it requires all my strength to pull it up4 7,in fastening the string to the leather the hole must be very small and the know as flat as possible1 and it is even well to put a small piece of kid under the knot4 ,when ,i first made this experiment1 not having taken these precautions1 it did not succeed well1 owing to air getting in through the hole47 ,i now drop it on this stone weight1 and so heavily is it pressed down upon it by the atmosphere that ,i can lift the weight without its breaking away from it4 ,have you ever tried to pick limpets off a rock8 ,if so1 you know how tight they cling4 the limpet clings to the rock just in the same way as this leather does to the stone2 the little animal exhausts the air inside it's shell1 and then it is pressed against the rock by the whole weight of the air above4 ,perhaps you will wonder how it is that if we have a weight of #ae lbs4 pressing on every square inch of our bodies1 it does not crush us4 ,and1 indeed1 it amounts on the whole to a weight of about #ae tons upon the body of a grown man4 ,it would crush us if it were not that there are gases and fluids inside our bodies which press outwards and balance the weight so that we do not feel it at all4 ,this is why ,mr4 ,glaisher's veins swelled and he grew giddy in thin air4 ,the gases and fluids inside his body were pressing outwards as much as when he was below1 but the air outside did not press so heavily1 and so all the natural condition of his body was disturbed4 ,i hope we now realize how heavily the air presses down upon our earth1 but it is equally necessary to understand how1 being elastic1 it also presses upwards2 and we can prove this by a simple experiment4 ,i fill this tumbler with water1 and keeping a piece of card firmly pressed against it1 ,i turn the whole upside- down4 ,when ,i now take my hand away you would naturally expect the card to fall1 and the water to be spilt4 ,but no6 the card remains as if glued to the tumbler1 kept there entirely by the air pressing upwards against it4 7,the engraver has drawn the tumbler only half full of water4 ,the experiment will succeed quite as well in this way if the tumbler be turned over quickly1 so that part of the air escapes between the tumbler and the card1 and therefore the space above the water is occupied by air less dense than that outside47 ,and now we are almost prepared to understand how we can weigh the invisible air4 ,one more experiment first4 ,i have here what is called a ,u tube1 because it is shaped like a large ,u4 ,i pour some water in it till it is about half full1 and you will notice that the water stands at the same height in both arms of the tube1 because the air presses on both surfaces alike4 ,putting my thumb on one end ,i tilt the tube carefully1 so as to make the water run up to the end of one arm1 and then turn it back again4 ,but the water does not now return to its even position1 it remains up in the arm on which my thumb rests4 ,why is this8 ,because my thumb keeps back the air from pressing at that end1 and the whole weight of the atmosphere rests on the water at the other end4 ,and so we learn that not only has the atmosphere real weight1 but we can see the effects of this weight by making it balance a column of water or any other liquid4 ,in the case of the wetted leather we felt the weight of the air1 here we see its effects4 ,now when we wish to see the weight of the air we consult a barometer1 which works really just in the same way as the water in this tube4 ,an ordinary upright barometer is simply a straight tube of glass filled with mercury or quicksilver1 and turned upside-down in a small cup of mercury4 ,the tube is a little more than #cj inches long1 and though it is quite full of mercury before it is turned up1 yet directly it stands in the cup the mercury falls1 till there is a height of about #cj inches between the surface of the mercury in the cup1 and that of the mercury in the tube4 ,as it falls it leaves an empty space above the mercury which is called a vacuum1 because it has no air in it4 ,now1 the mercury is under the same conditions as the water was in the ,u tube1 there is no pressure upon it at the top of the tube1 while there is a pressure of #ae lbs4 upon it in the bowl1 and therefore it remains held up in the tube4 ,week #i ,but why will it not remain more than #cj inches high in the tube8 ,you must remember it is only kept up in the tube at all by the air which presses on the mercury in the cup4 ,and that column of mercury now balances the pressure of the air outside1 and presses down on the mercury in the cup at its mouth just as much as the air does on the rest4 ,so this cup and tube act exactly like a pair of scales4 ,the air outside is the thing to be weighed at one end as it presses on the mercury1 the column answers to the leaden weight at the other end which tells you how heavy the air is4 ,now if the bore of this tube is made an inch square1 then the #cj inches of mercury in it weigh exactly #ae lbs1 and so we know that the weight of the air is #ae lbs4 upon every square inch1 but if the bore of the tube is only half a square inch1 and therefore the #cj inches of mercury only weigh #g #a_/b lbs4 instead of #ae lbs41 the pressure of the atmosphere will also be halved1 because it will only act upon half a square inch of surface1 and for this reason it will make no difference to the height of the mercury whether the tube be broad or narrow4 ,but now suppose the atmosphere grows lighter1 as it does when it has much damp in it4 ,the barometer will show this at once1 because there will be less weight on the mercury in the cup1 therefore it will not keep the mercury pushed so high up in the tube4 ,in other words1 the mercury in the tube will fall4 ,let us suppose that one day the air is so much lighter that it presses down only with a weight of #ad #a_/b lbs4 to the square inch instead of #ae lbs4 ,then the mercury would fall to #bi inches1 because each inch is equal to the weight of half a pound4 ,now1 when the air is damp and very full of water-vapour it is much lighter1 and so when the barometer falls we expect rain4 ,sometimes1 however1 other causes make the air light1 and then1 although the barometer is low1 no rain comes1 ,again1 if the air becomes heavier the mercury is pushed up above #cj to #ca inches1 and in this way we are able to weigh the invisible air-ocean all over the world1 and tell when it grows lighter or heavier4 ,this then1 is the secret of the barometer4 ,we cannot speak of the thermometer today1 but ,i should like to warn you in passing that it has nothing to do with the weight of the air1 but only with heat1 and acts in quite a different way4 ,and now we have been so long hunting out1 testing and weighing our aerial ocean1 that scarcely any time is left us to speak of its movements or the pleasant breezes which it makes for us in our country walks4 ,did you ever try to run races on a very windy day8 ,ah6 then you feel the air strongly enough2 how it beats against your face and chest1 and blows down your throat so as to take your breath away2 and what hard work it is to struggle against it6 ,stop for a moment and rest1 and ask yourself1 what is the wind8 ,why does it blow sometimes one way and sometimes another1 and sometimes not at all8 ,wind is nothing more than air moving across the surface of the earth1 which as it passes along bends the tops of the trees1 beats against the houses1 pushes the ships along by their sails1 turns the windmill1 carries off the smoke from cities1 whistles through the keyhole1 and moans as it rushes down the valley4 ,what makes the air restless8 why should it not lie still all round the earth8 ,it is restless because1 as you will remember1 its atoms are kept pressed together near the earth by the weight of the air above1 and they take every opportunity1 when they can find more room1 to spread out violently and rush into the vacant space1 and this rush we call a wind4 ,imagine a great number of active schoolboys all crowded into a room till they can scarcely move their arms and legs for the crush1 and then suppose all at once a large door is opened4 ,will they not all come tumbling out pell-mell1 one over the other1 into the hall beyond1 so that if you stood in their way you would most likely be knocked down8 ,well1 just this happens to the air- atoms2 when they find a space before them into which they can rush1 they come on helter-skelter1 with such force that you have great difficulty in standing against them1 and catch hold of something to support you for fear you should be blown down4 ,but how come they to find any empty space to receive them8 ,to answer this we must go back again to our little active invisible fairies the sunbeams4 ,when the sun-waves come pouring down upon the earth they pass through the air almost without heating it4 ,but not so with the ground2 there they pass down only a short distance and then are thrown back again4 ,and when these sun- waves come quivering back they force the atoms of the air near the earth apart and make it lighter2 so that the air close to the surface of the heated ground becomes less heavy than the air above it1 and rises just as a cork rises in water4 ,you know that hot air rises in the chimney2 for if you put a piece of lighted paper on the fire it is carried up by the draught of air1 often even before it can ignite4 ,now just as the hot air rises from the fire1 so it rises from the heated ground up into higher parts of the atmosphere4 and as it rises it leaves only thin air behind it1 and this cannot resist the strong cold air whose atoms are struggling and trying to get free1 and they rush in and fill the space4 ,one of the simplest examples of wind is to be found at the seaside4 there in the daytime the land gets hot under the sunshine1 and heats the air1 making it grow light and rise4 ,meanwhile the sunshine on the water goes down deeper1 and so does not send back so many heat-waves into the air2 consequently the air on the top of the water is cooler and heavier1 and it rushes in from over the sea to fill up the space on the shore left by the warm air as it rises4 ,this is why the seaside is so pleasant in hot weather4 ,during the daytime a light sea-breeze nearly always sets in from the sea to the land4 ,when night comes1 however1 then the land loses its heat very quickly1 because it has not stored it up and the land-air grows cold2 but the sea1 which has been hoarding the sun-waves down in its depths1 now gives them up to the atmosphere above it1 and the sea-air becomes warm and rises4 ,for this reason it is now the turn of the cold air from the land to spread over the sea1 and you have a land-breeze blowing off the shore4 ,again1 the reason why there are such steady winds1 called the trade winds1 blowing towards the equator1 is that the sun is very hot at the equator1 and hot air is always rising there and making room for colder air to rush in4 ,we have not time to travel farther with the moving air1 though its journeys are extremely interesting2 but if1 when you read about the trade and other winds1 you will always picture to yourselves warm air made light by the heat rising up into space and cold air expanding and rushing in to fill its place1 ,i can promise you that you will not find the study of aerial currents so dry as many people imagine it to be4 ,we are now able to form some picture of our aerial ocean4 ,we can imagine the active atoms of oxygen floating in the sluggish nitrogen1 and being used up in every candle-flame1 gas-jet and fire1 and in the breath of all living beings2 and coming out again tied fast to atoms of carbon and making carbonic acid4 ,then we can turn to trees and plants1 and see them tearing these two apart again1 holding the carbon fast and sending the invisible atoms of oxygen bounding back again into the air1 ready to recommence work4 ,we can picture all these air-atoms1 whether of oxygen or nitrogen1 packed close together on the surface of the earth1 and lying gradually farther and farther apart1 as they have less weight above them1 till they become so scattered that we can only detect them as they rub against the flying meteors which flash into light4 ,we can feel this great weight of air pressing the limpet on to the rock2 and we can see it pressing up the mercury in the barometer and so enabling us to measure its weight4 ,lastly1 every breath of wind that blows past us tells us how this aerial ocean is always moving to and fro on the face of the earth2 and if we think for a moment how much bad air and bad matter it must carry away1 as it goes from crowded cities to be purified in the country1 we can see how1 in even this one way alone1 it is a great blessing to us4 ,yet even now we have not mentioned many of the beauties of our atmosphere4 ,it is the tiny particles floating in the air which scatter the light of the sun so that it spreads over the whole country and into shady places4 ,the sun's rays always travel straight forward2 and in the moon1 where there is no atmosphere1 there is no light anywhere except just where the rays fall4 ,but on our earth the sun-waves hit against the myriads of particles in the air and glide off them into the corners of the room or the recesses of a shady lane1 and so we have light spread before us wherever we walk in the daytime1 instead of those deep black shadows which we can see through a telescope on the face of the moon4 ,again1 it is electricity playing in the air-atoms which gives us the beautiful lightning and the grand aurora borealis1 and even the twinkling of the starts is produced entirely by minute changes in the air4 ,if it were not for our aerial ocean1 the stars would stare at us sternly1 instead of smiling with the pleasant twinkle-twinkle which we have all learned to love as little children4 ,all these questions1 however1 we must leave for the present2 only ,i hope you will be eager to read about them wherever you can1 and open your eyes to learn their secrets4 ,for the present we must be content if we can even picture this wonderful ocean of gas spread round our earth1 and some of the work it does for us4 ,we said in the last lecture that without the sunbeams the earth would be cold1 dark1 and frost-ridden4 ,with sunbeams1 but without air1 it would indeed have burning heat1 side by side with darkness and ice1 but it could have no soft light4 our planet might look beautiful to others1 as the moon does to us1 but it could have comparatively few beauties of its own4 ,with the sunbeams and the air1 we see it has much to make it beautiful4 ,but a third worker is wanted before our planet can revel in activity and life4 ,this worker is water2 and in the next lecture we shall learn something of the beauty and the usefulness of the drops of water on their travels4 ,week #aj ,,lecture ,,iv4 ,a ,,drop ,,of ,,water ,,on ,,its ,,travels ,we are going to spend an hour to-day in following a drop of water on its travels4 ,if ,i dip my finger in this basin of water and lift it up again1 ,i bring with it a small glistening drop out of the body of water below1 and hold it before you4 ,tell me1 have you any idea where this drop has been8 what changes it has undergone1 and what work it has been doing during all the long ages that water has lain on the face of the earth8 ,it is a drop now1 but it was not so before ,i lifted it out of the basin2 then it was part of a sheet of water1 and will be so again if ,i let it fall4 ,again1 if ,i were to put this basin on the stove till all the water had boiled away1 where would my drop be then8 ,where would it go8 ,what forms will it take before it reappears in the rain-cloud1 the river1 or the sparkling dew8 ,these are questions we are going to try to answer to-day2 and first1 before we can in the least understand how water travels1 we must call to mind what we have learnt about the sunbeams and the air4 ,we must have clearly pictured in our imagination those countless sun-waves which are for ever crossing space1 and especially those larger and slower undulations1 the dark heat- waves2 for it is these1 you will remember1 which force the air- atoms apart and make the air light1 and it is also these which are most busy in sending water on its travels4 ,but not these alone4 ,the sun-waves might shake the water-drops as much as they liked and turn them into invisible vapour1 but they could not carry them over the earth if it were not for the winds and currents of that aerial ocean which bears the vapour on its bosom1 and wafts it to different regions of the world4 ,let us try to understand how these two invisible workers1 the sun-waves and the air1 deal with the drops of water4 ,i have here a kettle 7,fig4 #ah1 p4 #gf7 boiling over a spirit-lamp1 and ,i want you to follow minutely what is going on in it4 ,first1 in the flame of the lamp1 atoms of the spirit drawn up from below are clashing with the oxygen-atoms in the air4 ,this1 as you know1 causes heat-waves and light-waves to move rapidly all round the lamp4 ,the light-waves cannot pass through the kettle1 but the heat-waves can1 and as they enter the water inside they agitate it violently4 ,quicker1 and still more quickly1 the particles of water near the bottom of the kettle move to and fro and are shaken apart2 and as they become light they rise through the colder water letting another layer come down to be heated in its turn4 ,the motion grows more and more violent1 making the water hotter and hotter1 till at last the particles of which it is composed fly asunder1 and escape as invisible vapour4 ,if this kettle were transparent you would not see any steam above the water1 because it is in the form of an invisible gas4 ,but as the steam comes out of the mouth of the kettle you see a cloud4 ,why is this8 ,because the vapour is chilled by coming out into the cold air1 and its particles are drawn together again into tiny1 tiny drops of water1 to which ,dr4 ,tyndall has given the suggestive name of water-dust4 ,if you hold a plate over the steam you can catch these tiny drops1 though they will run into one another almost as you are catching them4 ,the clouds you see floating in the sky are made of exactly the same kind of water-dust as the cloud from the kettle1 and ,i wish to show you that this is also really the same as the invisible steam within the kettle4 ,i will do so by an experiment suggested by ,dr4 ,tyndall4 ,here is another spirit-lamp1 which ,i will hold under the cloud of steam - see6 the cloud disappears6 ,as soon as the water-dust is heated the heat-waves scatter it again into invisible particles1 which float away into the room4 ,even without the spirit-lamp1 you can convince yourself that water-vapour may be invisible2 for close to the mouth of the kettle you will see a short blank space before the cloud begins4 ,in this space there must be steam1 but it is still so hot that you cannot see it2 and this proves that heat-waves can so shake water apart as to carry it away invisibly right before your eyes4 ,now1 although we never see any water travelling from our earth up into the skies1 we know that it goes there1 for it comes down again in rain1 and so it must go up invisibly4 ,but where does the heat come from which makes this water invisible8 ,not from below1 as in the case of the kettle1 but from above1 pouring down from the sun4 ,wherever the sun-waves touch the rivers1 ponds1 lakes1 seas1 or fields of ice and snow upon our earth1 they carry off invisible water-vapour4 ,they dart down through the top layers of the water1 and shake the water-particles forcibly apart2 and in this case the drops fly asunder more easily and before they are so hot1 because they are not kept down by a great weight of water above1 as in the kettle1 but find plenty of room to spread themselves out in the gaps between the air-atoms of the atmosphere4 ,can you imagine these water-particles1 just above any pond or lake1 rising up and getting entangled among the air-atoms8 ,they are very light1 much lighter than the atmosphere2 and so1 when a great many of them are spread about in the air which lies just over the pond1 they make it much lighter than the layer of air above1 and so help it to rise1 while the heavier layer of air comes down ready to take up more vapour4 ,in this way the sun-waves and the air carry off water everyday1 and all day long1 from the top of lakes1 rivers1 pools1 springs1 and seas1 and even from the surface of ice and snow4 ,without any fuss or noise or sign of any kind1 the water of our earth is being drawn up invisibly into the sky4 ,it has been calculated that in the ,indian ,ocean three-quarters of an inch of water is carried off from the surface of the sea in one day and night2 so that as much as #bb feet1 or a depth of water about twice the height of an ordinary room1 is silently and invisibly lifted up from the whole surface of the ocean in one year4 ,it is true this is one of the hottest parts of the earth1 where the sun-waves are most active2 but even in our own country many feet of water are drawn up in the summer-time4 ,what1 then1 becomes of all this water8 ,let us follow it as it struggles upwards to the sky4 ,we see it in our imagination first carrying layer after layer of air up with it from the sea till it rises far above our heads and above the highest mountains4 ,but now1 call to mind what happens to the air as it recedes from the earth4 ,do you not remember that the air-atoms are always trying to fly apart1 and are only kept pressed together by the weight of air above them8 ,well1 so this water-laden air rises up1 its particles1 no longer so much pressed together1 begin to separate1 and as all work requires an expenditure of heat1 the air becomes colder1 and then you know at once what must happen to the invisible vapour1 -- it will form into tiny water-drops1 like the steam from the kettle4 ,and so1 as the air rises and becomes colder1 the vapour gathers into the visible masses1 and we can see it hanging in the sky1 and call it clouds4 ,when these clouds are highest they are about ten miles from the earth1 but when they are made of heavy drops and hang low down1 they sometimes come within a mile of the ground4 ,look up at the clouds as you go home1 and think that the water of which they are made has all been drawn up invisibly through the air4 ,not1 however1 necessarily here in ,london1 for we have already seen that air travels as wind all over the world1 rushing in to fill spaces made by rising air wherever they occur1 and so these clouds may be made of vapour collected in the ,mediterranean1 or in the ,gulf of ,mexico off the coast of ,america1 or even1 if the wind is from the north1 of chilly particles gathered from the surface of ,greenland ice and snow1 and brought here by the moving currents of air4 ,only1 of one thing we may be sure1 that they come from the water of our earth4 ,sometimes1 if the air is warm1 these water-particles may travel a long way without ever forming into clouds2 and on a hot1 cloudless day the air is often very full of invisible vapour4 ,then1 if a cold wind comes sweeping along1 high up in the sky1 and chills this vapour1 it forms into great bodies of water-dust clouds1 and the sky is overcast4 ,at other times clouds hang lazily in a bright sky1 and these show us that just where they are 7as in ,fig4 #ai7 the air is cold and turns the invisible vapour rising from the ground into visible water-dust1 so that exactly in those spaces we see it as clouds4 ,such clouds form often on warm1 still summer's day1 and they are shaped like masses of wool1 ending in a straight line below4 ,they are not merely hanging in the sky1 they are really resting upon a tall column of invisible vapour which stretches right up from the earth2 and that straight line under the clouds marks the place where the air becomes cold enough to turn this invisible vapour into visible drops of water4 ,week #aa ,and now1 suppose that while these or any other kind of clouds are overhead1 there comes along either a very cold wind1 or a wind full of vapour4 ,as it passes through the clouds1 it makes them very full of water1 for1 if it chills them1 it makes the water- dust draw more closely together2 or1 if it brings a new load of water-dust1 the air is fuller than it can hold4 ,in either case a number of water-particles are set free1 and our fairy force cohesion seizes upon them at once and forms them into large water-drops4 ,then they are much heavier than the air1 and so they can float no longer1 but down they come to the earth in a shower of rain4 ,there are other ways in which the air may be chilled1 and rain made to fall1 as1 for example1 when a wind laden with moisture strikes against the cold tops of mountains4 ,thus the ,khasia ,hills in ,india which face the ,bay of ,bengal1 chill the air which crosses them on its way from the ,indian ,ocean4 ,the wet winds are driven up the sides of the hills1 the air expands1 and the vapour is chilled1 and forming into drops1 falls in torrents of rain4 ,sir ,j4 ,hooker tells us that as much as #ejj inches of rain fell in these hills in nine months4 ,that is to say1 if you could measure off all the ground over which the rain fell1 and spread the whole nine months' rain over it1 it would make a lake #ejj inches1 or more than #dj feet deep6 ,you will not be surprised that the country on the other side of these hills gets hardly any rain1 for all the water has been taken out of the air before it comes there4 ,again for example in ,england1 the wind comes to ,cumberland and ,westmorland over the ,atlantic1 full of vapour1 and as it strikes against the ,pennine ,hills it shakes off its watery load2 so that the lake district is the most rainy in ,england1 with the exception perhaps of ,wales1 where the high mountains have the same effect4 ,in this way1 from different causes1 the water of which the sun has robbed our rivers and seas1 comes back to us1 after it has travelled to various parts of the world1 floating on the bosom of the air4 ,but it does not always fall straight back into the rivers and seas again1 a large part of it falls on the land1 and has to trickle down slopes and into the earth1 in order to get back to its natural home1 and it is often caught on its way before it can reach the great waters4 ,go to any piece of ground which is left wild and untouched you will find it covered with grass weeds1 and other plants2 if you dig up a small plot you will find innumerable tiny roots creeping through the ground in every direction4 ,each of these roots has a sponge-like mouth by which the plant takes up water4 ,now1 imagine rain-drops falling on this plot of ground and sinking into the earth4 ,on every side they will find rootlets thirsting to drink them in1 and they will be sucked up as if by tiny sponges1 and drawn into the plants1 and up the stems to the leaves4 ,here1 as we shall see in ,lecture ,,vii41 they are worked up into food for the plant1 and only if the leaf has more water than it needs1 some drops may escape at the tiny openings under the leaf1 and be drawn up again by the sun-waves as invisible vapour into the air4 ,again1 much of the rain falls on hard rock and stone1 where it cannot sink in1 and then it lies in pools till it is shaken apart again into vapour and carried off in the air4 ,nor is it idle here1 even before it is carried up to make clouds4 ,we have to thank this invisible vapour in the air for protecting us from the burning heat of the sun by day and intolerable frost by night4 ,let us for a moment imagine that we can see all that we know exists between us and the sun4 ,first1 we have the fine ether across which the sunbeams travel1 beating down upon our earth with immense force1 so that in the sandy desert they are like a burning fire4 ,then we have the coarser atmosphere of oxygen and nitrogen atoms hanging in this ether1 and bending the minute sun- waves out of their direct path4 ,but they do very little to hinder them on their way1 and this is why in very dry countries the sun's heat is so intense4 ,the rays beat down mercilessly1 and nothing opposes them4 ,lastly1 in damp countries we have the larger but still invisible particles of vapour hanging about among the air-atoms4 ,now1 these watery particles1 although they are very few 7only about one twenty-fifth part of the whole atmosphere71 do hinder the sun-waves4 ,for they are very greedy of heat1 and though the light-waves pass easily through them1 they catch the heat-waves and use them to help themselves to expand4 ,and so1 when there is invisible vapour in the air1 the sunbeams come to us deprived of some of their heat-waves1 and we can remain in the sunshine without suffering from the heat4 ,this is how the water-vapour shields us by day1 but by night it is still more useful4 ,during the day our earth and the air near it have been storing up the heat which has been poured down on them1 and at night1 when the sun goes down1 all this heat begins to escape again4 ,now1 if there were no vapour in the air1 this heat would rush back into space so rapidly that the ground would become cold and frozen even on a summer's night1 and all but the most hardy plants would die4 ,but the vapour which formed a veil against the sun in the day1 now forms a still more powerful veil against the escape of the heat by night4 ,it shuts in the heat- waves1 and only allows them to make their way slowly upwards from the earth - thus producing for us the soft1 balmy nights of summer and preventing all life being destroyed in the winter4 ,perhaps you would scarcely imagine at first that it is this screen of vapour which determines whether or not we shall have dew upon the ground4 ,have you ever thought why dew forms1 or what power has been at work scattering the sparkling drops upon the grass8 ,picture to yourself that it has been a very hot summer's day1 and the ground and the grass have been well warmed1 and that the sun goes down in a clear sky without any clouds4 ,at once the heat- waves which have been stored up in the ground1 bound back into the air1 and here some are greedily absorbed by the vapour1 while others make their way slowly upwards4 ,the grass1 especially1 gives out these heat-waves very quickly1 because the blades1 being very thin1 are almost all surface4 ,in consequence of this they part with their heat more quickly than they can draw it up from the ground1 and become cold4 ,now the air lying just above the grass is full of invisible vapour1 and the cold of the blades1 as it touches them1 chills the water- particles1 and they are no longer able to hold apart1 but are drawn together into drops on the surface of the leaves4 ,we can easily make artificial dew for ourselves4 ,i have here a bottle of ice which has been kept outside the window4 ,when ,i bring it into the warm room a mist forms rapidly outside the bottle4 ,this mist is composed of water-drops1 drawn out of the air of the room1 because the cold glass chilled the air all round it1 so that it gave up its invisible water to form dew-drops4 ,just in this same way the cold blades of grass chill the air lying above them1 and steal its vapour4 ,but try the experiment1 some night when a heavy dew is expected1 of spreading a thin piece of muslin over some part of the grass1 supporting it at the four corners with pieces of stick so that it forms an awning4 ,though there may be plenty of dew on the grass all round1 yet under this awning you will find scarcely any4 ,the reason of this is that the muslin checks the heat-waves as they rise from the grass1 and so the grass-blades are not chilled enough to draw together the water-drops on their surface4 ,if you walk out early in the summer mornings and look at the fine cobwebs flung across the hedges1 you will see plenty of drops on the cobwebs themselves sparkling like diamonds2 but underneath on the leaves there will be none1 for even the delicate cobweb has been strong enough to shut in the heat-waves and keep the leaves warm4 ,again1 if you walk off the grass on to the gravel path1 you find no dew there4 ,why is this8 ,because the stones of the gravel can draw up heat from the earth below as fast as they give it out1 and so they are never cold enough to chill the air which touches them4 ,on a cloudy night also you will often find little or no dew even on the grass4 ,the reason of this is that the clouds give back heat to the earth1 and so the grass does not become chilled enough to draw the water-drops together on its surface4 ,but after a hot1 dry day1 when the plants are thirsty and there is little hope of rain to refresh them1 then they are able in the evening to draw the little drops from the air and drink them in before the rising sun comes again to carry them away4 ,but our rain-drop undergoes other changes more strange than these4 ,till now we have been imagining it to travel only where the temperature is moderate enough for it to remain in a liquid state as water4 ,but suppose that when it is drawn up into the air it meets with such a cold blast as to bring it to the freezing point4 ,if it falls into this blast when it is already a drop1 then it will freeze into a hailstone1 and often on a hot summer's day we may have a severe hailstorm1 because the rain-drops have crossed a bitterly cold wind as they were falling1 and have been frozen into round drops of ice4 ,but if the water-vapour reaches the freezing air while it is still an invisible gas1 and before it has been drawn into a drop1 then its history is very different4 ,the ordinary force of cohesion has then no power over the particles to make them into watery globes1 but its place is taken by the fairy process of crystallization1 and they are formed into beautiful white flakes1 to fall in a snow-shower4 ,i want you to picture this process to yourselves1 for if once you can take an interest in the wonderful power of nature to build up crystals1 you will be astonished how often you will meet with instances of it1 and what pleasure it will add to your life4 ,the particles of nearly all substances1 when left free and not hurried1 can build themselves into crystal forms4 ,if you melt salt in water and then let all the water evaporate slowly1 you will get salt-crystals2 -- beautiful cubes of transparent salt all built on the same pattern4 ,the same is true of sugar2 and if you will look at the spikes of an ordinary stick of sugar-candy1 such as ,i have here1 you will see the kind of crystals which sugar forms4 ,you may even pick out such shapes as these from the common crystallized brown sugar in the sugar basin1 or see them with a magnifying glass on a lump of white sugar4 ,but it is not only easily melted substances such as sugar and salt which form crystals4 ,the beautiful stalactite grottos are all made of crystals of lime4 ,diamonds are crystals of carbon1 made inside the earth4 ,rock-crystals1 which you know probably under the name of ,irish diamonds1 are crystallized quartz2 and so1 with slightly different colourings1 are agates1 opals1 jasper1 onyx1 cairngorms1 and many other precious stones4 ,iron1 copper1 gold1 and sulphur1 when melted and cooled slowly build themselves into crystals1 each of their own peculiar form1 and we see that there is here a wonderful order1 such as we should never have dreamt of1 if we had not proved it4 ,if you possess a microscope you may watch the growth of crystals yourself by melting some common powdered nitre in a little water till you find that no more will melt in it4 ,then put a few drops of this water on a warm glass slide and place it under the microscope4 ,as the drops dry you will see the long transparent needles of nitre forming on the glass1 and notice how regularly these crystals grow1 not by taking food inside like living beings1 but by adding particle to particle on the outside evenly and regularly4 ,week #ab ,can we form any idea why the crystals build themselves up so systematically8 ,dr4 ,tyndall says we can1 and ,i hope by the help of these small bar magnets to show you how he explains it4 ,these little pieces of steel1 which ,i hope you can see lying on this white cardboard1 have been rubbed along a magnet until they have become magnets themselves1 and ,i can attract and lift up a needle with any one of them4 ,but if ,i try to lift one bar with another1 ,i can only do it by bringing certain ends together4 ,i have tied a piece of red cotton 7c1 ,fig4 #ba7 round one end of each of the magnets1 and if ,i bring two red ends together they will not cling together but roll apart4 ,if1 on the contrary1 ,i put a red end against an end where there is not cotton1 then the two bars cling together4 ,this is because every magnet has two poles or points which are exactly opposite in character1 and to distinguish them one is called the positive pole and the other the negative pole4 ,now when ,i bring two red ends1 that is1 two positive poles together1 they drive each other away4 ,see6 the magnet ,i am not holding runs away from the other4 ,but if ,i bring a red end and a black end1 that is1 a positive and a negative end together1 then they are attracted and cling4 ,i will make a triangle 7,a1 ,fig4 #ba7 in which a black end and a red end always come together1 and you see the triangle holds together4 ,but now if ,i take off the lower bar and turn it 7,b1 ,fig4 #ba7 so that two red ends and two black ends come together1 then this bar actually rolls back from the others down the cardboard4 ,if ,i were to break these bars into a thousand pieces1 each piece would still have two poles1 and if they were scattered about near each other in such a way that they were quite free to move1 they would arrange themselves always so two different poles came together4 ,now picture to yourselves that all the particles of those substances which form crystals have poles like our magnets1 then you can imagine that when the heat which held them apart is withdrawn and the particles come very near together1 they will arrange themselves according to the attraction of their poles and so build up regular and beautiful patterns4 ,so1 if we could travel up to the clouds where this fairy power of crystallization is at work1 we should find the particles of water-vapour in a freezing atmosphere being built up into minute solid crystals of snow4 ,if you go out after a snow-shower and search carefully1 you will see that the snow-flakes are not mere lumps of frozen water1 but beautiful six-pointed crystal stars1 so white and pure that when we want to speak of anything being spotlessly white1 you say that it is white as snow4 ,some of these crystals are simply flat slabs with six sides1 others are stars with six rods or spikes springing from the centre1 others with six spikes each formed like a delicate fern4 ,no less than a thousand different forms of delicate crystals have been found among snowflakes1 but though there is such a great variety1 yet they are all built on the six-sided and six-pointed plan1 and are all rendered dazzlingly white by the reflection of the light from the faces of the crystals and the tiny air-bubbles built up within them4 ,this1 you see1 is why1 when the snow melts1 you have only a little dirty water in your hand2 the crystals are gone and there are no more air-bubbles held prisoners to act as looking-glasses to the light4 ,hoar-frost is also made up of tiny water-crystals1 and is nothing more than frozen dew hanging on the blades of grass and from the trees4 ,but how about ice8 ,here1 you will say1 is frozen water1 and yet we see no crystals1 only a clear transparent mass4 ,here1 again1 ,dr4 ,tyndall helps us4 ,he says 7and as ,i have proved it true1 so may you for yourselves1 if you will7 that if you take a magnifying glass1 and look down on the surface of ice on a sunny day1 you will see a number of dark1 six-sided stars1 looking like flattened flowers1 and in the centre of each a bright spot4 ,these flowers1 which are seen when the ice is melting1 are our old friends the crystal stars turning into water1 and the bright spot in the middle is a bubble of empty space1 left because the watery flower does not fill up as much room as the ice of the crystal star did4 ,and this leads us to notice that ice always takes up more room than water1 and that this is the reason why our water-pipes burst in severe frosts2 for as the water freezes it expands with great force1 and the pipe is cracked1 and then when the thaw comes on 1 and the water melts again1 it pours through the crack it has made4 ,it is not difficult to understand why ice should take more room2 for we know that if we were to try to arrange bricks end to end in star-like shapes1 we must leave some spaces between1 and could not pack them so closely as if they lay side by side4 ,and so1 when this giant force of crystallization constrains the atoms of frozen water to grow into star-like forms1 the solid mass must fill more room than the liquid water1 and when the star melts1 this space reveals itself to us in the bright spot of the centre4 ,we have now seen our drop of water under all its various forms of invisible gas1 visible steam1 cloud1 dew1 hoar-frost1 snow1 and ice1 and we have only time shortly to see it on its travels1 not merely up and down1 as hitherto1 but round the world4 ,we must first go to the sea as the distillery1 or the place from which water is drawn up invisibly1 in its purest state1 into the air2 and we must go chiefly to the seas of the tropics1 because here the sun shines most directly all the year round1 sending heat-waves to shake the water-particles asunder4 ,it has been found by experiment that1 in order to turn #a lb4 of water into vapour1 as much heat must be used as is required to melt #e lbs4 of iron2 and if you consider for a moment how difficult iron is to melt1 and how we can keep an iron poker in a hot fire and yet it remains solid1 this will help you to realize how much heat the sun must pour down in order to carry off such a constant supply of vapour from the tropical seas4 ,now1 when all this vapour is drawn up into the air1 we know that some of it will form into clouds as it gets chilled high up in the sky1 and then it will pour down again in those tremendous floods of rain which occur in the tropics4 ,but the sun and air will not let it all fall down at once1 and the winds which are blowing from the equator to the poles carry large masses of it away with them4 ,then1 as you know1 it will depend on many things how far this vapour is carried4 ,some of it1 chilled by cold blasts1 or by striking on cold mountain tops1 as it travels northwards1 will fall in rain in ,europe and ,asia1 while that which travels southwards may fall in ,south ,america1 ,australia1 or ,new ,zealand1 or be carried over the sea to the ,south ,pole4 ,wherever it falls on the land as rain1 and is not used by plants1 it will do one of two things2 either it will run down in streams and form brooks and rivers1 and so at last find its way back to the sea1 or it will sink deep in the earth till it comes upon some hard rock through which it cannot get1 and then1 being hard pressed by the water coming on behind1 it will rise up again through cracks1 and come to the surface as a spring4 ,these springs1 again1 feed rivers1 sometimes above- ground1 sometimes for long distances under-ground2 but one way or another at last the whole drains back into the sea4 ,but if the vapour travels on till it reaches high mountains in cooler lands1 such as the ,alps of ,switzerland2 or is carried to the poles and to such countries as ,greenland or the ,antarctic ,continent1 then it will come down as snow1 forming immense snow- fields4 ,and here a curious change takes place in it4 ,if you make an ordinary snowball and work it firmly together1 it becomes very hard1 and if you then press it forcibly into a mould you can turn it into transparent ice4 ,and in the same way the snow which falls in ,greenland and on the high mountains of ,switzerland becomes very firmly pressed together1 as it slides down into the valleys4 ,it is like a crowd of people passing from a broad thoroughfare into a narrow street4 ,as the valley grows narrower and narrower the great mass of snow in front cannot move down quickly1 while more and more is piled up by the snowfall behind1 and the crowd and crush grow denser and denser4 ,in this way the snow is pressed together till the air that was hidden in its crystals1 and which gave it its beautiful whiteness1 is all pressed out1 and the snow-crystals themselves are squeezed into one solid mass of pure1 transparent ice4 ,then we have what is called a glacier1 or river of ice1 and this solid river comes creeping down till1 in ,greenland1 it reaches the edge of the sea4 ,there it is pushed over the brink of the land1 and large pieces snap off1 and we have icebergs4 ,these icebergs - made1 remember1 of the same water which was first draw up from the tropics - float on the wide sea1 and melting in its warm currents1 topple over and over99 7,a floating iceberg must have about eight times as much ice under the water as it has above1 and therefore1 when the lower part melts in a warm current1 the iceberg loses its balance and tilts over1 so as to rearrange itself round the centre of gravity47 till they disappear and mix with the water1 to be carried back again to the warm ocean from which they first started4 ,in ,switzerland the glaciers cannot reach the sea1 but they move down into the valleys till they come to a warmer region1 and there the end of the glacier melts1 and flows away in a stream4 ,the ,rhone and many other rivers are fed by the glaciers of the ,alps2 and as these rivers flow into the sea1 our drop of water again finds its way back to its home4 ,but when it joins itself in this way to its companions1 from whom it was parted for a time1 does it come back clear and transparent as it left them8 ,from the iceberg it does indeed return pure and clear2 for the fairy ,crystallization will have no impurities1 not even salt1 in her ice-crystals1 and so as they melt they give back nothing but pure water to the sea4 ,yet even icebergs bring down earth and stones frozen into the bottom of the ice1 and so they feed the sea with mud4 ,but the drops of water in rivers are by no means as pure as when they rose up into the sky4 ,we shall see in the next lecture how rivers carry down not only sand and mud all along their course1 but even solid matter such as salt1 lime1 iron1 and flint1 dissolved in the clear water1 just as sugar is dissolved1 without our being able to see it4 ,the water1 too1 which has sunk down into the earth1 takes up much matter as it travels along4 ,you all know that the water you drink from a spring is very different from rain-water1 and you will often find a hard crust at the bottom of kettles and in boilers1 which is formed of the carbonate of lime which is driven out of the clear water when it is boiled4 ,the water has become hard in consequence of having picked up and dissolved the carbonate of lime on its way through the earth1 just in the same way as water would become sweet if you poured it through a sugar-cask4 ,you will also have heard of iron-springs1 sulphur-springs1 and salt-springs1 which come out of the earth1 even if you have never tasted any of them1 and the water of all these springs finds its way back at last to the sea4 ,and now1 can you understand why sea-water should taste salt and bitter8 ,every drop of water which flows from the earth to the sea carries something with it4 ,generally1 there is so little of any substance in the water that we cannot taste it1 and we call it pure water2 but the purest of spring or river-water has always some solid matter dissolved in it1 and all this goes to the sea4 ,now1 when the sun-waves come to take the water out of the sea again1 they will have nothing but the pure water itself2 and so all these salts and carbonates and other solid substances are left behind1 and we taste them in sea-water4 ,some day1 when you are at the seaside1 take some extra water and set it on the hob till a great deal has simmered gently away1 and the liquid is very thick4 ,then take a drop of this liquid1 and examine it under a microscope4 ,as it dries up gradually1 you will see a number of crystals forming1 some square - and these will be crystals of ordinary salt2 some oblong - these will be crystals of gypsum or alabaster2 and others of various shapes4 ,then1 when you see how much matter from the land is contained in sea-water1 you will no longer wonder that the sea is salt2 on the contrary1 you will ask1 ,why does it not grow salter every year8 ,the answer to this scarcely belongs to our history of a drop of water1 but ,i must just suggest it to you4 ,in the sea are numbers of soft-bodied animals1 like the jelly animals which form the coral1 which require hard material for their shells or the solid branches on which they live1 and they are greedily watching for these atoms of lime1 of flint1 or magnesia1 and of other substances brought down into the sea4 ,it is with lime and magnesia that the tiny chalk-builders form their beautiful shells1 and the coral animals their skeletons1 while another class of builders use the flint2 and when these creatures die1 their remains go to form fresh land at the bottom of the sea2 and so1 though the earth is being washed away by the rivers and springs it is being built up again1 out of the same materials1 in the depths of the great ocean4 ,and now we have reached the end of the travels of our drop of water4 ,we have seen it drawn up by the fairy heat1 invisible into the sky2 there fairy cohesion seized it and formed it into water-drops and the giant1 gravitation1 pulled it down again to the earth4 ,or1 if it rose to freezing regions1 the fairy of crystallization built it up into snow-crystals1 again to fall to the earth1 and either to be melted back into water by heat1 or to slide down the valleys by force of gravitation1 till it became squeezed into ice4 ,we have detected it1 when invisible1 forming a veil round our earth1 and keeping off the intense heat of the sun's rays by day1 or shutting it in by night4 ,we have seen it chilled by the blades of grass1 forming sparkling dew-drops or crystals of hoar-frost1 glistening in the early morning sun2 and we have seen it in the dark underground1 being drunk up greedily by the roots of plants4 ,we have started with it from the tropics1 and travelled over land and sea1 watching it forming rivers1 or flowing underground in springs1 or moving onwards to the high mountains or the poles1 and coming back again in glaciers and icebergs4 ,through all this1 while it is being carried hither and thither by invisible power1 we find no trace of its becoming worn out1 or likely to rest from its labours4 ,ever onwards it goes1 up and down1 and round and round the world1 taking many forms1 and performing many wonderful feats4 ,we have seen some of the work that it does1 in refreshing the air1 feeding the plants1 giving us clear1 sparkling water to drink1 and carrying matter to the sea2 but besides this1 it does a wonderful work in altering all the face of our earth4 ,this work we shall consider in the next lecture1 on ,the two great ,sculptors - ,water and ,ice4 ,week #ac ,,lecture ,v4 ,,the ,,two ,,great ,,sculptors - ,,water ,,and ,,ice4 ,in our last lecture we saw that water can exist in three forms3-- #ast1 as an invisible vapour2 #bnd1 as liquid water2 #crd1 as solid snow and ice4 ,to-day we are going to take the two last of these forms1 water and ice1 and speak of them as sculptors4 ,to understand why they deserve this name we must first consider what the work of a sculptor is4 ,if you go into a statuary yard you will find there large blocks of granite1 marble1 and other kinds of stone1 hewn roughly into different shapes2 but if you pass into the studio1 where the sculptor himself is at work you will find beautiful statues1 more or less finished2 and you will see that out of rough blocks of stone he has been able to cut images which look like living forms4 ,you can even see by their faces whether they are intended to be sad1 or thoughtful1 or gay1 and by their attitude whether they are writhing in pain1 or dancing with joy1 or resting peacefully4 ,how has all this history been worked out from the shapeless stone8 ,it has been done by the sculptor's chisel4 ,a piece chipped off here1 a wrinkle cut there1 a smooth surface rounded off in another place1 so as to give a gentle curve2 all these touches gradually shape the figure and mould it out of the rough stone1 first into a rude shape and afterwards1 by delicate strokes1 into the form of a living being4 ,now1 just in the same way as the wrinkles and curves of a statue are cut by the sculptor's chisel1 so the hills and valleys1 the steep slopes and gentle curves on the face of our earth1 giving it all its beauty1 and the varied landscapes we love so well1 have been cut out by water and ice passing over them4 ,it is true that some of the greater wrinkles of the earth1 the lofty mountains1 and the high masses of land which rise above the sea 1 have been caused by earthquakes and shrinking of the earth4 ,we shall not speak of these to-day1 but put them aside as belonging to the rough work of the statuary yard4 ,but when once these large masses are put ready for water to work upon1 then all the rest of the rugged wrinkles and gentle slopes which make the country so beautiful are due to water and ice1 and for this reason ,i have called them sculptors4 ,go for a walk in the country1 or notice the landscape as you travel on a railway journey4 ,you pass by hills and through valleys1 through narrow steep gorges cut in hard rock1 or through wild ravines up the sides of which you can hardly scramble4 ,then you come to grassy slopes and to smooth plains across which you can look for miles without seeing a hill2 or1 when you arrive at the seashore1 you clamber into caves and grottos1 and along dark narrow passages leading from one bay to another4 ,all these - hills1 valleys1 gorges1 ravines1 slopes1 plains1 caves1 grottos1 and rocky shores - have been cut out by the water4 ,day by day and year by year1 while everything seems to us to remain the same1 this industrious sculptor is chipping away1 a few grains here1 a corner there1 a large mass in another place1 till he gives to the country its own peculiar scenery1 just as the human sculptor gives expression to his statue4 ,our work to-day will consist in trying to form some idea of the way in which water thus carves out the surface of the earth1 and we will begin by seeing how much can be done by our old friends the rain-drops before they become running streams4 ,everyone must have noticed that whenever rain falls on soft ground it makes small round holes in which it collects1 and then sinks into the ground1 forcing its way between the grains of earth4 ,but you would hardly think that the beautiful pillars in ,fig4 #bd have been made entirely in this way by rain beating upon and soaking into the ground4 ,where these pillars stand there was once a solid mass of clay and stones1 into which the rain-drops crept1 loosening the earthly particles2 and then when the sun dried the earth again cracks were formed1 so that the next shower loosened it still more1 and carried some of the mud down into the valley below4 ,but here and there large stones were buried in the clay1 and where this happened the rain could not penetrate1 and the stones became the tops of tall pillars of clay1 washed into shape by the rain beating on its sides1 but escaping the general destruction of the rest of the mud4 ,in this way the whole valley has been carved out into fine pillars1 some still having capping-stones1 while others have lost them1 and these last will soon be washed away4 ,we have no such valleys of earth-pillars here in ,england1 but you may sometimes see tiny pillars under bridges where the drippings have washed away the earth between the pebbles1 and such small examples which you can observe for yourselves are quite as instructive as more important ones4 ,another way in which rain changes the surface of the earth is by sinking down through loose soil from the top of a cliff to a depth of many feet till it comes to solid rock1 and then lying spread over a wide apace4 ,here it makes a kind of watery mud1 which is a very unsafe foundation for the hill of earth above it1 and so after a time the whole mass slips down and makes a fresh piece of land at the foot of the cliff4 ,if you have ever been at the ,isle of ,wight you will have seen an undulating strip of ground1 called the ,undercliff1 at ,ventnor and other places1 stretching all along the sea below the high cliffs4 ,this land was once at the top of the cliff1 and came down by succession of landslips such as we have been describing4 ,a very great landslip of this kind happened in the memory of living people1 at ,lyme ,regis1 in ,dorsetshire1 in the year #ahci4 ,you will easily see how in forming earth-pillars and causing landslips rain changes the face of the country1 but these are only rare effects of water4 ,it is when the rain collects in brooks and forms rivers that it is most busy in sculpturing the land4 ,look out some day into the road or the garden where the ground slopes a little1 and watch what happens during a shower of rain4 ,first the rain-drops run together in every little hollow of the ground1 then the water begins to flow along any ruts or channels it can find1 lying here and there in pools1 but always making its way gradually down the slope4 ,meanwhile from other parts of the ground little rills are coming1 and these all meet in some larger ruts where the ground is lowest1 making one great stream1 which at last empties itself into the gutter or an area1 or finds its way down some grating4 ,now just this1 which we can watch whenever a heavy shower of rain comes down on the road1 happens also all over the world4 ,up in the mountains1 where there is always a great deal of rain1 little rills gather and fall over the mountain sides1 meeting in some stream below4 ,then1 as this stream flows on1 it is fed by many runnels of water1 which come from all parts of the country1 trickling along ruts1 and flowing in small brooks and rivulets down the gentle slope of the land till they reach the big stream1 which at last is important enough to be called a river4 ,sometimes this river comes to a large hollow in the land and there the water gathers and forms a lake2 but still at the lower end of this lake out it comes again1 forming a new river1 and growing and growing by receiving fresh streams until at last it reaches the sea4 ,the ,river ,thames1 which you all know1 and whose course you will find clearly described in ,mr4 ,huxley's ',physiography1' drains in this way no less than one-seventh of the whole of ,england4 ,all the rain which falls in ,berkshire1 ,oxfordshire1 ,middlesex1 ,hertfordshire1 ,surrey1 the north of ,wiltshire and north-west of ,kent1 the south of ,buckinghamshire and of ,gloucestershire1 finds its way into the ,thames2 making an area of #fafj square miles over which every rivulet and brook trickle down to the one great river1 which bears them to the ocean4 ,and so with every other area of land in the world there is some one channel towards which the ground on all sides slopes gently down1 and into this channel all the water will run1 on its way to the sea4 ,but what has this to do with sculpture or cutting out of valleys8 ,if you will only take a glass of water out of any river1 and let it stand for some hours1 you will soon answer this question for yourself4 ,for you will find that even from river water which looks quite clear1 a thin layer of mud will fall to the bottom of the glass1 and if you take the water when the river is swollen and muddy you will get quite a thick deposit4 ,this shows that the brooks1 the streams1 and the rivers wash away the land as they flow over it and carry it from the mountains down to the valleys1 and from the valleys away out into the sea4 ,but besides earthly matter1 which we can see1 there is much matter dissolved in the water of rivers 7as we mentioned in the last lecture71 and this we cannot see4 ,if you use water which comes out of a chalk country you will find that after a time the kettle in which you have been in the habit of boiling this water has a hard crust on its bottom and sides1 and this crust is made of chalk or carbonate of lime1 which the water took out of the rocks when it was passing through them4 ,professor ,bischoff has calculated that the river ,rhine carries past ,bonn every year enough carbonate of lime dissolved in its water to make #ccb1jjj million oyster-shells1 and that if all these shells were built into a cube it would measure #efj feet4 ,week #ad ,imagine to yourselves the whole of ,st4 ,paul's churchyard filled with oyster-shells1 built up in a large square till they reached half as high again as the top of the cathedral1 then you will have some idea of the amount of chalk carried invisibly past ,bonn in the water of the ,rhine every year4 ,since all this matter1 whether brought down as mud or dissolved1 comes from one part of the land to be carried elsewhere or out to sea1 it is clear that some gaps and hollows must be left in the places from which it is taken4 ,let us see how these gaps are made4 ,have you ever clambered up the mountainside1 or even up one of those small ravines in the hillside1 which have generally a little stream trickling through them8 ,if so1 you must have noticed the number of pebbles1 large and small1 lying in patches here and there in the stream1 and many pieces of broken rock1 which are often scattered along the sides of the ravine2 and how1 as you climb1 the path grows steeper1 and the rocks become rugged and stick out in strange shapes4 ,the history of this ravine will tell us a great deal about the carving of water4 ,once it was nothing more than a little furrow in the hillside down which the rain found its way in a thin thread-like stream4 ,but by and by1 as the stream carried down some of the earth1 and the furrow grew deeper and wider1 the sides began to crumble when the sun dried up the rain which had soaked in4 ,then in winter1 when the sides of the hill were moist with the autumn rains1 frost came and turned the water to ice1 and so made the cracks still larger1 and the swollen steam rushing down1 caught the loose pieces of rock and washed them down into its bed4 ,here they were rolled over and over1 and grated against each other1 and were ground away till they became rounded pebbles1 such as lie in the foreground of the picture 7,fig4 #be72 while the grit which was rubbed off them was carried farther down by the stream4 ,and so in time this became a little valley1 and as the stream cut it deeper and deeper1 there was room to clamber along the sides of it1 and ferns and mosses began to cover the naked stone1 and small trees rooted themselves along the banks1 and this beautiful little nook sprang up on the hill-side entirely by the sculpturing of water4 ,shall you not feel a fresh interest in all the little valleys1 ravines1 and gorges you meet with in the country1 if you can picture them being formed in this way year by year8 ,there are many curious differences in them which you can study for yourselves4 ,some will be smooth1 broad valleys and here the rocks have been soft and easily worn1 and water trickling down the sides of the first valley has cut other channels so as to make smaller valleys running across it4 ,in other places there will be narrow ravines1 and here the rocks have been hard1 so that they did not wear away gradually1 but broke off and fell in blocks1 leaving high cliffs on each side4 ,in some places you will come to a beautiful waterfall1 where the water has tumbled over a steep cliff1 and then eaten its way back1 just like a saw cutting through a piece of wood4 ,there are two things in particular to notice in a waterfall like this4 ,first1 how the water and spray dash against the bottom of the cliff down which it falls1 and grind the small pebbles against the rock4 ,in this way the bottom of the cliff is undermined1 and so great pieces tumble down from time to time1 and keep the fall upright instead of its being sloped away at the top1 and becoming a mere steam4 ,secondly1 you may often see curious cup-shaped holes1 called pot-holes1 in the rocks on the sides of a waterfall1 and these also are concerned in its formation4 ,in these holes you will generally find two or three small pebbles1 and you have here a beautiful example of how water uses stones to grind away the face of the earth4 ,these holes are made entirely by the falling water eddying round and round in a small hollow of the rock1 and grinding the pebbles which it has brought down1 against the bottom and sides of this hollow1 just as you grind round a pestle in a mortar4 ,by degrees the hole grows deeper and deeper and though the first pebbles are probably ground down to powder1 others fall in1 and so in time there is a great hole perforated right through1 helping to make the rock break and fall away4 ,in this and other ways the water works its way back in a surprising manner4 ,the ,isle of ,wight gives us some good instances of this2 ,alum ,bay ,chine and the celebrated ,blackgang ,chine have been entirely cut out by waterfalls4 ,but the best know and most remarkable example is the ,niagara ,falls1 in ,america4 ,here1 the ,river ,niagara first wanders through a flat country1 and then reaches the great ,lake ,erie in a hollow of the plain4 ,after that1 it flows gently down for about fifteen miles1 and then the slope becomes greater and it rushes on to the ,falls of ,niagara4 ,these falls are not nearly so high as many people imagine1 being only #afe feet1 or about half the height of ,st4 ,paul's ,cathedral1 but they are #bgjj feet or nearly half-a-mile wide1 and no less than #fgj1jjj tons of water fall over them every minute1 making magnificent clouds of spray4 ,sir ,charles ,lyell1 when he was at ,niagara1 came to the conclusion that1 taking one year with another1 these falls eat back the cliff at the rate of about one foot a year1 as you can easily imagine they would do1 when you think with what force the water must dash against the bottom of the falls4 ,in this way a deep cleft has been cut right back from ,queenstown for a distance of seven miles1 to the place where the falls are now4 ,this helps us a little to understand how very slowly and gradually water cuts its way2 for if a foot a year is about the average of the waste of the rock1 it will have taken more than thirty-five thousand years for that channel of seven miles to be made4 ,but even this chasm cut by the falls of ,niagara is nothing compared with the canyons of ,colarado4 ,canyon is a ,spanish word for a rocky gorge1 and these gorges are indeed so grand1 that if we had not seen in other places what water can do1 we should never have been able to believe that it could have cut out these gigantic chasms4 ,for more than three hundred miles the ,river ,colorado1 coming down from the ,rocky ,mountains1 has eaten its way through a country made of granite and hard beds of limestone and sandstone1 and it has cut down straight through these rocks1 leaving walls from half-a-mile to a mile high1 standing straight up from it4 ,the cliffs of the ,great ,canyon1 as it is called1 stretch up for more than a mile above the river which flows in the gorge below6 ,fancy yourselves for a moment in a boat on this river1 as shown in ,figure #bg1 and looking up at these gigantic walls of rock towering above you4 ,even half-way up them1 a man1 if he could get there1 would be so small you could not see him without a telescope2 while the opening at the top between the two walls would seem so narrow at such an immense distance that the sky above would have the appearance of nothing more than a narrow streak of blue4 ,yet these huge chasms have not been made by any violent breaking apart of the rocks or convulsion of an earthquake4 ,no1 they have been gradually1 silently1 and steadily cut through by the river which now glides quietly in the wider chasms1 or rushes rapidly through the narrow gorges at their feet4 ,no description1 says ,lieutenant ,ives1 one of the first explorers of this river1 can convey the idea of the varied and majestic grandeur of this peerless waterway4 ,wherever the river turns1 the entire panorama changes4 ,stately facades1 august cathedrals1 amphitheatres1 rotundas1 castellated walls1 and rows of time-stained ruins1 surmounted by every form of tower1 minaret1 dome and spire1 have been moulded from the cyclopean masses of rock that form the mighty defile4 ,who will say1 after this1 that water is not the grandest of all sculptors1 as it cuts through hundreds of miles of rock1 forming such magnificent granite groups1 not only unsurpassed but unequalled by any of the works of man8 ,but we must not look upon water only as a cutting instrument1 for it does more than merely carve out land in one place1 it also carries it away and lays it down elsewhere2 and in this it is more like a modeller in clay1 who smooths off the material from one part of his figure to put it upon another4 ,running water is not only always carrying away mud1 but at the same time laying it down here and there wherever it flows4 ,when a torrent brings down stones and gravel from the mountains1 it will depend on the size and weight of the pieces how long they will be in falling through the water4 ,if you take a handful of gravel and throw it into a glass full of water1 you will notice that the stones in it will fall to the bottom at once1 the grit and coarse sand will take longer in sinking1 and lastly1 the fine sand will be an hour or two in settling down1 so that the water becomes clear4 ,now1 suppose that this gravel were sinking in the water of a river4 ,the stones would be buoyed up as long as the river was very full and flowed very quickly1 but they would drop through sooner than the coarse sand4 ,the coarse sand in its turn would begin to sink as the river flowed more slowly1 and would reach the bottom while the fine sand was still borne on4 ,lastly1 the fine sand would sink through very1 very slowly1 and only settle in comparatively still water4 ,from this it will happen that stones will generally lie near to the bottom of torrents at the foot of the banks from which they fall1 while the gravel will be carried on by the stream after it leaves the mountains4 ,this too1 however1 will be laid down when the river comes into a more level country and runs more slowly4 ,or it may be left together with the finer mud in a lake1 as in the lake of ,geneva1 into which the ,rhone flows laden with mud and comes out at the other end clear and pure4 ,but if no lake lies in the way the finer earth will still travel on1 and the river will take up more and more as it flows1 till at last it will leave this too on the plains across which it moves sluggishly along1 or will deposit it at its mouth when it joins the sea4 ,week #ae ,you all know the history of the ,nile2 how1 when the rains fall very heavily in ,march and ,april in the mountains of ,abyssinia1 the river comes rushing down and brings with it a load of mud which it spreads out over the ,nile valley in ,egypt4 ,this annual layer of mud is so thin that it takes a thousand years for it to become #b or #c feet thick2 but besides that which falls in the valley a great deal is taken to the mouth of the river and there forms new land1 making what is called the ,delta of the ,nile4 ,alexandria1 ,rosetta1 and ,damietta1 are towns which are all built on land made of ,nile mud which was carried down ages and ages ago1 and which has now become firm and hard like the rest of the country4 ,you will easily remember other deltas mentioned in books1 and all these are made of the mud carried down from the land to the sea4 ,the delta of the ,ganges and ,brahmapootra in ,india1 is actually as large as the whole of ,england and ,wales1 7#eh1caa square miles47 and the ,river ,mississippi in ,america drains such a large tract of country that its delta grows1 ,mr4 ,geikie tells us1 at the rate of #hf yards in year4 ,all this new land laid down in ,egypt1 in ,india1 in ,america1 and in other places1 is the work of water4 ,even on the ,thames you may see mud-banks1 as at ,gravesend1 which are made of earth brought from the interior of ,england4 ,but at the mouth of the ,thames the sea washes up very strongly every tide1 and so it carries most of the mud away and prevents a delta growing up there4 ,if you will look about when you are at the seaside1 and notice wherever a stream flows down into the sea1 you may even see little miniature deltas being formed there1 though the sea generally washes them away again in a few hours1 unless the place is well sheltered4 ,this1 then1 is what becomes of the earth carried down by rivers4 ,either on plains1 or in lakes1 or in the sea1 it falls down to form new land4 ,but what becomes of the dissolved chalk and other substances8 ,we have seen that a great deal of it is used by river and sea animals to build their shells and skeletons1 and some of it is left on the surface of the ground by springs when the water evaporates4 ,it is this carbonate of lime which forms a hard crust over anything upon which it may happen to be deposited1 and then these things are called petrified4 ,but it is in the caves and hollows of the earth that this dissolved matter is built up into the most beautiful forms4 ,if you have ever been to ,buxton in ,derbyshire1 you will probably have visited a cavern called ,poole's ,cavern1 not far from there1 which when you enter it looks as if it were built up entirely of rods of beautiful transparent white glass1 hanging from the ceiling1 from the walls1 or rising up from the floor4 ,in this cavern1 and many others like it1997,see the picture at the head of the lecture47 water comes dripping through the roof1 and as it falls carbonate of lime forms itself into a thin1 white film on the roof1 often making a complete circle1 and then1 as the water drips from it day by day1 it goes on growing and growing till it forms a long needle-shaped or tube-shaped rod1 hanging like an icicle4 ,these rods are called stalactites1 and they are so beautiful1 as their minute crystals glisten when a light is taken into the cavern1 that one of them near ,tenby is called the ,fairy ,chamber4 ,meanwhile1 the water which drips on to the floor also leaves some carbonate of lime where it falls1 and this forms a pillar1 growing up towards the roof1 and often the hanging stalactites and the rising pillars 7called stalagmites7 meet in the middle and form one column4 ,and thus we see that underground1 as well as aboveground1 water moulds beautiful forms in the crust of the earth4 ,at ,adelsberg1 near ,trieste1 there is a magnificent stalactite grotto made of a number of chambers one following another1 with a river flowing through them2 and the famous ,mammoth ,cave of ,kentucky1 more than ten miles long1 is another example of these wonderful limestone caverns4 ,but we have not yet spoken of the sea1 and this surely is not idle in altering the shape of the land4 ,even the waves themselves in a storm wash against the cliffs and bring down stones and pieces of rock on to the shore below4 ,and they help to make cracks and holes in the cliffs1 for as they dash with force against them they compress the air which lies in the joints of the stone and cause it to force the rock apart1 and so larger cracks are made and the cliff is ready to crumble4 ,it is1 however1 the stones and sand and pieces of rock lying at the foot of the cliff which are most active in wearing it away4 ,have you never watched the waves breaking upon a beach in a heavy storm8 ,how they catch up the stones and hurl them down again1 grinding them against each other6 ,at high tide in such a storm these stones are thrown against the foot of the cliff1 and each blow does something towards knocking away part of the rock1 till at last1 after many storms1 the cliff is undermined and large pieces fall down4 ,these pieces are in their turn ground down to pebbles which serve to batter against the remaining rock4 ,professor ,geikie tells us that the waves beat in a storm against the ,bell ,rock ,lighthouse with as much force as if you dashed a weight of #c tons against every square inch of the rock1 and ,stevenson found stones of #b tons' weight which had been thrown during storms right over the ledge of the lighthouse4 ,think what force there must be in waves which can lift up such a rock and throw it1 and such force as this beats upon our sea-coasts and eats away the land4 ,fig4 #bh is a sketch on the shores of ,arbroath which ,i made some years ago4 ,you will not find it difficult to picture to yourselves how the sea has eaten away these cliffs till some of the strongest pieces which have resisted the waves stand out by themselves in the sea4 ,that cave in the left-hand corner ends in a narrow dark passage from which you come out on the other side of the rocks into another bay4 ,such caves as these are made chiefly by the force of the waves and the air1 bringing down pieces of rock from under the cliff and so making a cavity1 and then as the waves roll these pieces over and over and grind them against the sides1 the hole is made larger4 ,there are many places on the ,english coast where large pieces of the road are destroyed by the crumbling down of cliffs when they have been undermined by caverns such as these4 ,thus1 you see1 the whole of the beautiful scenery of the sea - the shores1 the steep cliffs1 the quiet bays1 the creeks and caverns - are all the work of the sculptor water2 and he works best where the rocks are hardest1 for there they offer him a good stout wall to batter1 whereas in places where the ground is soft it washes down into a gradual gentle slope1 and so the waves come flowing smoothly in and have no power to eat away the shore4 ,and now1 what has ,ice got to do with the sculpturing of the land8 ,first1 we must remember how much the frost does in breaking up the ground4 ,the farmers know this1 and always plough after a frost1 because the moisture1 freezing in the ground1 has broken up the clods1 and done half their work for them4 ,but this is not the chief work of ice4 ,you will remember how we learnt in our last lecture that snow1 when it falls on the mountains1 gradually slides down into the valleys1 and is pressed together by the gathering snow behind until it becomes moulded into a solid river of ice 7see ,fig4 #bi1 ,frontispiece74 ,in ,greenland and in ,norway there are enormous ice-rivers or glaciers1 and even in ,switzerland some of them are very large4 ,the ,aletsch glacier1 in the ,alps1 is fifteen miles long1 and some are even longer than this4 ,they move very slowly - on an average about #bj to #bg inches in the centre1 and #ac to #ai inches at the sides every twenty-four hours1 in the summer and autumn4 ,how they move1 we cannot stop to discuss now2 but if you will take a slab of thin ice and rest it upon its two ends only1 you can prove to yourself that ice does bend1 for in a few hours you will find that its own weight has drawn it down in the centre1 so as to form a curve4 ,this will help you to picture to yourselves how glaciers can adapt themselves to the windings of the valley1 creeping slowly onwards until they come down to a point where the air is warm enough to melt them1 and then the ice flows away in a stream of water4 ,it is very curious to see the number of little rills running down the great masses of ice at the glacier's mouth1 bringing down with them gravel1 and every now and then a large stone1 which falls splashing into the stream below4 ,if you look at the glacier in the ,frontispiece1 you will see that these stones come from those long lines of stones and boulders stretching along the sides and centre of the glacier4 ,it is easy to understand where the stones at the side come from2 for we have seen that damp and frost cause pieces to break off the surface of the rocks1 and it is natural that these pieces should roll down the steep sides of the mountains on to the glacier4 ,but the middle row requires some explanation4 ,look to the back of the picture1 and you will see that this line of stones is made of two side rows1 which come from the valleys above4 ,two glaciers1 you see1 have there joined into one1 and so made a heap of stones all along their line of junction4 ,these stones are being continually1 though slowly1 conveyed by the glacier1 from all the mountains along its sides1 down to the place where it melts4 ,here it lets them fall1 and they are gradually piled up till they form great walls of stone1 which are called moraines4 ,some of the moraines left by the larger glaciers of olden time1 in the country near ,turin1 form high hills1 rising up even to #aejj feet4 ,therefore1 if ice did no more than carry these stone blocks1 it would alter the face of the country2 but it does much more than this4 ,as the glacier moves along1 it often cracks for a considerable way across its surface1 and this crack widens and widens1 until at last it becomes a great gaping chasm1 or crevasse as it is called1 so that you can look down it right to the bottom of the glacier4 ,into these crevasses large blocks of rock fall1 and when the chasm is closed again as the ice presses on1 these masses are frozen firmly into the bottom of the glacier1 much in the same way as a steel cutter is fixed in the bottom of a plane4 ,and they do just the same kind of work2 for as the glacier slides down the valley1 they scratch and grind the rocks underneath them1 rubbing themselves away1 it is true1 but also scraping away the ground over which they move4 ,in this way the glacier becomes a cutting instrument1 and carves out the valleys deeper and deeper as it passes through them4 ,you may always know where a glacier has been1 even if no trace of ice remains2 for you will see rocks with scratches along them which have been cut by these stones2 and even where the rocks have not been ground away1 you will find them rounded like those in the left-hand of the ,frontispiece1 showing that the glacier- plane has been over them4 ,these rounded rocks are called roches moutonnees1 because at the distance they look like sheep lying down4 ,you have only to look at the stream flowing from the mouth of a glacier to see what a quantity of soil it has ground off from the bottom of the valley2 for the water is thick1 and coloured a deep yellow by the mud it carries4 ,this mud soon reaches the rivers into which the streams run2 and such rivers as the ,rhone and the ,rhine are thick with matter brought down from the ,alps4 ,the ,rhone leaves this mud in the ,lake of ,geneva1 flowing out at the other end quite clear and pure4 ,a mile and a half of land has been formed at the head of the lake since the time of the ,romans by the mud thus brought down from the mountains4 ,thus we see that ice1 like water1 is always busy carving out the surface of the earth1 and sending down material to make new land elsewhere4 ,we know that in past ages the glaciers were much larger than they are in our time2 for we find traces of them over large parts of ,switzerland where glaciers do not now exist1 and huge blocks which could only have been carried by ice1 and which are called erratic blocks1 some of them as big as cottages1 have been left scattered over all the northern part of ,europe4 ,these blocks were a great puzzle to scientific men till1 in #ahdj1 ,professor ,agassiz showed that they must have been brought by ice all the way from ,norway and ,russia4 ,in those ancient days1 there were even glaciers in ,england2 for in ,cumberland and in ,wales you may see their work1 in scratched and rounded rocks1 and the moraines they have left4 ,llanberis ,pass1 so famous for its beauty1 is covered with ice-scratches1 and blocks are scattered all over the sides of the valley4 ,there is one block high up on the right-hand slope of the valley1 as you enter from the ,beddgelert side1 which is exactly poised upon another block1 so that it rocks to and fro4 ,it must have been left thus balanced when the ice melted round it4 ,you may easily see that these blocks were carried by ice1 and not by water1 because their edges are sharp1 whereas if they had been rolled in water1 they would have been smoothed down4 ,we cannot here go into the history of that great ,glacial ,period long ago1 when large fields of ice covered all the north of ,england2 but when you read it for yourselves and understand the changes on the earth's surface which we can see being made by ice now1 then such grand scenery as the rugged valleys of ,wales1 with large angular stone blocks scattered over them1 will tell you a wonderful story of the ice of bygone times4 ,and now we have touched lightly on the chief ways in which water and ice carve out the surface of the earth4 ,we have seen that rain1 rivers1 springs1 the waves of the sea1 frost1 and glaciers all do their part in chiselling out ravines and valleys1 and in producing rugged peaks or undulating plains - here cutting through rocks so as to form precipitous cliffs1 there laying down new land to add to the flat country - in one place grinding stones to powder1 in others piling them up in gigantic ridges4 ,we cannot go a step into the country without seeing the work of water around us2 every little gully and ravine tells us that the sculpture is going on2 every stream1 with its burden of visible or invisible matter1 reminds us that some earth is being taken away and carried to a new spot4 ,in our little lives we see indeed but the very small changes1 but by these we learn how greater ones have been brought about1 and how we owe the outline of all our beautiful scenery1 with its hills and valleys1 its mountains and plains1 its cliffs and caverns1 its quiet nooks and its grand rugged precipices1 to the work of the ,two great sculptors1 ,water and ,ice4 ,week #af ,lecture ,,vi ,,the ,,voices ,,of ,,nature ,,and ,,how ,,we ,,hear ,,them ,we have reached to-day the middle point of our course1 and here we will make a new start4 ,all the wonderful histories which we have been studying in the last five lectures have had little or nothing to do with living creatures4 ,the sunbeams would strike on our earth1 the air would move restlessly to and fro1 the water-drops would rise and fall1 the valleys and ravines would still be cut out by rivers 1 if there were no such thing as life upon the earth4 ,but without living things there could be none of the beauty which these changes bring about4 ,without plants1 the sunbeams1 the air and the water would be quite unable to clothe the bare rocks1 and without animals and man they could not produce light1 or sound1 or feeling of any kind4 ,in the next five lectures1 however1 we are going to learn something of the use living creatures make of the earth2 and to- day we will begin by studying one of the ways in which we are affected by the changes of nature1 and hear her voice4 ,we are all so accustomed to trust to our sight to guide us in most of our actions1 and to think of things as we see them1 that we often forget how very much we owe to sound4 ,and yet ,nature speaks to us so much by her gentle1 her touching1 or her awful sounds1 that the life of a deaf person is even more hard to bear than that of a blind one4 ,have you ever amused yourself with trying how many different sounds you can distinguish if you listen at an open window in a busy street8 ,you will probably be able to recognize easily the jolting of the heavy wagon or dray1 the rumble of the omnibus1 the smooth roll of the private carriage and the rattle of the light butcher's cart2 and even while you are listening for these1 the crack of the carter's whip1 the cry of the costermonger at his stall1 and the voices of the passers-by will strike upon you ear4 ,then if you give still more close attention you will hear the doors open and shut along the street1 the footsteps of the passengers1 the scraping of the shovel of the mud-carts2 nay1 if he happen to stand near1 you may even hear the jingling of the shoeblack's pence as he plays pitch and toss upon the pavement4 ,if you think for a moment1 does it not seem wonderful that you should hear all these sounds so that you can recognize each one distinctly while all the rest are going on around you8 ,but suppose you go into the quiet country4 ,surely there will be silence there4 ,try some day and prove it for yourself1 lie down on the grass in a sheltered nook and listen attentively4 ,if there be ever so little wind stirring you will hear it rustling gently through the trees2 or even if there is not this1 it will be strange if you do not hear some wandering gnat buzzing1 or some busy bee humming as it moves from flower to flower4 ,then a grasshopper will set up a chirp within a few yards of you1 or1 if all living creatures are silent1 a brook not far off may be flowing along with a rippling musical sound4 ,these and a hundred other noises you will hear in the most quiet country spot2 the lowing of the cattle1 the song of the birds1 the squeak of the field-mouse1 the croak of the frog1 mingling with the sound of the woodman's axe in the distance1 or the dash of some river torrent4 ,and beside these quiet sounds1 there are still other occasional voices of nature which speak to us from time to time4 ,the howling of the tempestuous wind1 the roar of the sea-waves in a storm1 the crash of thunder1 and the mighty noise of the falling avalanche2 such sounds as these tell us how great and terrible nature can be4 ,now1 has it ever occurred to you to think what sounds is1 and how it is that we hear all these things8 ,strange as it may seem1 if there were no creature that could hear upon the earth1 there would be no such thing as sound1 though all these movements in nature were going on just as they are now4 ,try and grasp this thoroughly1 for it is difficult at first to make people believe it4 ,suppose you were stone-deaf1 there would be no such thing as sound to you4 ,a heavy hammer falling on an anvil would indeed shake the air violently1 but since this air when it reached your ear would find a useless instrument1 it could not play upon it4 and it is this play on the drum of your ear and the nerves within it speaking to your brain which make sound4 ,therefore1 if all creatures on or around the earth were without ears or nerves of hearing1 there would be no instrument on which to play1 and consequently there would be no such thing as sound4 ,this proves that two things are needed in order that we may hear4 ,first1 the outside movement which plays on our hearing instrument2 and1 secondly1 the hearing instrument itself4 ,first1 then1 let us try to understand what happens outside our ears4 ,take a poker and tie a piece of string to it1 and holding the ends of the string to your ears1 strike the poker against the fender4 ,you will hear a very loud sound1 for the blow will set all the particles of the poker quivering1 and this movement will pass right along the string to the drum of your ear and play upon it4 ,now take the string away from you ears1 and hold it with your teeth4 ,stop your ears tight1 and strike the poker once more against the fender4 ,you will hear the sound quite as loudly and clearly as you did before1 but this time the drum of your ear has not been agitated4 ,how1 then1 has the sound been produced8 ,in this case1 the quivering movement has passed through your teeth into the bones of your hear1 and from them into the nerves1 and so produced sound in your brain4 ,and now1 as a final experiment1 fasten the string to the mantelpiece1 and hit it again against the fender4 ,how much feebler the sound is this time1 and how much sooner it stops6 ,yet still it reaches you1 for the movement has come this time across the air to the drums of your ear4 ,here we are back again in the land of invisible workers6 ,we have all been listening and hearing ever since we were babies1 but have we ever made any picture to ourselves of how sound comes to us right across a room or a field1 when we stand at one end and the person who calls is at the other8 ,since we have studied the aerial ocean1 we know that the air filling the space between us1 though invisible1 is something very real1 and now all we have to do is to understand exactly how the movement crosses this air4 ,this we shall do most readily by means of an experiment made by ,dr4 ,tyndall in his lectures on ,sound4 ,i have here a number of boxwood balls resting in a wooden tray which has a bell hung at the end of it4 ,i am going to take the end ball and roll it sharply against the rest1 and then ,i want you to notice carefully what happens4 ,see6 the ball at the other end has flow off and hit the bell1 so that you hear it ring4 ,yet the other balls remain where they were before4 ,why is this8 ,it is because each of the balls1 as it was knocked forwards1 had one in front of it to stop it and make it bound back again1 but the last one was free to move on4 ,when ,i threw this ball from my hand against the others1 the one in front of it moved1 and hitting the third ball1 bounded back again2 the third did the same to the fourth1 the fourth to the fifth1 and so on to the end of the line4 ,each ball thus came back to its place1 but it passed the shock on to the last ball1 and the ball to the bell4 ,if ,i now put the balls close up to the bell1 and repeat the experiment1 you still hear the sound1 for the last ball shakes the bell as if it were a ball in front of it4 ,now imagine these balls to be atoms of air1 and the bell your ear4 ,if ,i clap my hands and so hit the air in front of them1 each air-atom hits the next just as the balls did1 and though it comes back to its place1 it passes the shock on along the whole line to the atom touching the drum of your ear1 and so you receive a blow4 ,but a curious thing happens in the air which you cannot notice in the balls4 ,you must remember that air is elastic1 just as if there were springs between the atoms as in the diagram1 ,fig4 #ca1 and so when any shock knocks the atoms forward1 several of them can be crowded together before they push on those in front4 ,then1 as soon as they have passed the shock on1 they rebound and begin to separate again1 and so swing to and fro till they come to rest4 meanwhile the second set will go through just the same movements1 and will spring apart as soon as they have passed the shock on to a third set1 and so you will have one set of crowded atoms and one set of separated atoms alternately all along the line1 and the same set will never be crowded two instants together4 ,you may see an excellent example of this in a luggage train in a railway station1 when the trucks are left to bump each other till they stop4 ,you will see three or four trucks knock together1 then they will pass the shock on to the four in front1 while they themselves bound back and separate as far as their chains will let them3 the next four trucks will do the same1 and so a kind of wave of crowded trucks passes on to the end of the train1 and they bump to and fro till the whole comes to a standstill4 ,try to imagine a movement like this going on in the line of air- atoms1 the drum of your ear being at the end4 ,those which are crowded together at that end will hit on the drum of your ear and drive the membrane which covers it inwards2 then instantly the wave will change1 these atoms will bound back1 and the membrane will recover itself again1 but only to receive a second blow as the atoms are driven forwards again1 and so the membrane will be driven in and out till the air has settled down4 ,this you see is quite different to the waves of light which moves in crests and hollows4 ,indeed1 it is not what we usually understand by a wave at all1 but a set of crowdings and partings of atoms of air which follow each other rapidly across the air4 ,a crowding of atoms is called a condensation1 and a parting is called a rarefaction1 and when we speak of the length of a wave of sound1 we mean the distance between two condensations1 or between two rarefactions4 ,although each atom of air moves a very little way forwards and then back1 yet1 as a long row of atoms may be crowded together before they begin to part1 a wave is often very long4 ,when a man talks in an ordinary bass voice1 he makes sound-waves from #h to #ab feet long2 a woman's voice makes shorter waves1 from #b to #d feet long1 and consequently the tone is higher1 as we shall presently explain4 ,and now ,i hope that some one is anxious to ask why1 when ,i clap my hands1 anyone behind me or at the side1 can hear it as well or nearly as well as you who are in front4 ,this is because ,i give a shock to the air all round my hands1 and waves go out on all sides1 making as it were gloves of crowdings and partings widening and widening away from the clap as circles widen on a pond4 ,thus the waves travel behind me1 above me1 and on all sides1 until they hit the walls1 the ceiling1 and the floor of the room1 and wherever you happen to be1 they hit upon your ear4 ,week #ag ,if you can picture to yourself these waves spreading out in all directions1 you will easily see why sound grows fainter at the distance4 ,just close round my hands when ,i clap them1 there is a small quantity of air1 and so the shock ,i give it is very violent1 but as the sound-waves spread on all sides they have more and more air to move1 and so the air-atoms are shaken less violently and strike with less force on your ear4 ,if we can prevent the sound-wave from spreading1 then the sound is not weakened4 ,the ,frenchman ,biot found that a low whisper could be heard distinctly for a distance of half a mile through a tube1 because the waves could not spread beyond the small column of air4 ,but unless you speak into a small space of some kind1 you cannot prevent the waves going out from you in all directions4 ,try and imagine that you see these waves spreading all round me now and hitting on your ears as they pass1 then on the ears of those behind you1 and on and on in widening globes till they reach the wall4 ,what will happen when they get there8 ,if the wall were thin1 as a wooden partition is1 they would shake it1 and it again would shake the air on the other side1 and so anyone in the next room would have the sound of my voice brought to their ear4 ,but something more will happen4 ,in any case the sound-waves hitting against the wall will bound back from it just as a ball bounds back when thrown against anything1 and so another set of sound-waves reflected from the wall will come back across the room4 ,if these waves come to your ear so quickly that they mix with direct waves1 they help to make the sound louder in this room than you would in the open air1 for the ,ha from my mouth and a second ,ha from the wall come to your ear so instantaneously that they make one sound4 ,this is why you can often hear better at the far end of a church when you stand against a screen or a wall1 then when you are half-way up the building nearer to the speaker1 because near the wall the reflected waves strike strongly on your ear and make the sound louder4 ,sometimes1 when the sound comes from a great explosion1 these reflected waves are so strong that they are able to break glass4 ,in the explosion of gunpowder in ,st4 ,john's ,wood1 many houses in the back streets had their windows broken2 for the sound-waves bounded off at angles from the walls and struck back upon them4 ,now suppose the wall were so far behind you that the reflected sound-waves only hit upon your ear after those coming straight from me had died away2 then you would hear the sound twice1 ,ha from me and ,ha from the wall1 and here you have an echo1 ,ha1 ha4 ,in order for this to happen in ordinary air1 you must be standing at least #ef feet away from the point from which the waves are reflected1 for then the second blow will come one-tenth of a second after the first one1 and that is long enough for you to feel them separately499 ,miss ,c4 ,a4 ,martineau tells a story of a dog which was terribly frightened by an echo4 ,thinking another dog was barking1 he ran forward to meet him1 and was very much astonished1 when1 as he came nearer the wall1 the echo ceased4 ,i myself once knew a case of this kind1 and my dog1 when he could find no enemy1 ran back barking1 till he was a certain distance off1 and then the echo of course began again4 ,he grew so furious at last that we had great difficulty in preventing him from flying at a strange man who happened to be passing at the time4 799,sound travels #aabj feet in a second1 in air of ordinary temperature1 and therefore #aab feet in the tenth of a second4 ,therefore the journey of #ef feet beyond you to reach the wall and #ef feet to return1 will occupy the sound-wave one-tenth of a second and separate the two sounds47 ,sometimes1 in the mountains1 walls of rock rise at some distance one behind another1 and then each one will send back its echo a little later than the rock before it1 so that the ,ha which you give will come back as a peal of laughter4 ,there is an echo in ,woodstock ,park which repeats the word twenty times4 ,again sometimes1 as in the ,alps1 the sound-waves coming back rebound from mountain to mountain and are driven backwards and forwards1 becoming fainter and fainter till they die away2 these echoes are very beautiful4 ,if you are now able to picture to yourselves one set of waves going to the wall1 and another set returning and crossing them1 you will be ready to understand something of that very difficult question1 ,how is it that we can hear many different sounds at one time and tell them apart8 ,have you ever watched the sea when its surface is much ruffled1 and noticed how1 besides the big waves of the tide1 there are numberless smaller ripples made by the wind blowing the surface of the water1 or the oars of a boat dipping in it1 or even rain- drops falling8 ,if you have done this you will have seen that all these waves and ripples cross each other1 and you can follow any one ripple with you eye as it goes on its way undisturbed by the rest4 ,or you may make beautiful crossing and recrossing ripples on a pond by throwing in two stones at a little distance from each other1 and here too you can follow any one wave on to the edge of the pond4 ,now just in this way the waves of sound1 in their manner of moving1 cross and recross each other4 ,you will remember too1 that different sounds make waves of different lengths1 just as the tide makes a long wave and the rain-drops tiny ones4 ,therefore each sound falls with its own peculiar wave upon your ear1 and you can listen to that particular wave just as you look at one particular ripple1 and then the sound becomes clear to you4 ,all this is what is going on outside your ear1 but what is happening in your ear itself8 ,how do these blows of the air speak to your brain8 ,by means of the following diagram1 ,fig4 #cc1 we will try to understand roughly our beautiful hearing instrument1 the ear4 ,first1 ,i want you to notice how beautifully the outside shell1 or concha as it is called1 is curbed round so that any movement of the air coming to it from the front is caught in it and reflected into the hole of the ear4 ,put your finger round your ear and feel how the gristly part is curved towards the front of your head4 ,this concha makes a curve much like the curve a deaf man makes with his hand behind his ear to catch the sound4 ,animals often have to raise their ears to catch the sound well1 but ours stand always ready4 ,when the air-waves have passed in at the hole of your ear1 they move all the air in the passage1 which is called the auditory1 or hearing1 canal4 ,this canal is lined with little hairs to keep out insects and dust1 and the wax which collects in it serves the same purpose4 ,but is too much wax collects1 it prevents the air from playing well upon the drum1 and therefore makes you deaf4 ,across the end of this canal1 a membrane or skin called the tympanum is stretched1 like the parchment over the head of a drum1 and it is this membrane which moves to and fro as the air-waves strike on it4 ,a violent box on the ear will sometimes break this delicate membrane1 or injure it1 and therefore it is very wrong to hit a person violently on the ear4 ,on the other side of this membrane1 inside the ear1 there is air1 which fills the whole of the inner chamber and the tube1 which runs down into the throat behind the nose1 and is called the ,eustachian tube after the man who discovered it4 ,this tube is closed at the end by a valve which opens and shuts4 ,if you breathe out strongly1 and then shut your mouth and swallow1 you will hear a little click in your ear4 ,this is because in swallowing you draw the air out of the ,eustachian tube and so draw in the membrane1 which clicks as it goes back again4 ,but unless you do this the tube and the whole chamber cavity behind the membrane remains full of air4 ,now1 as this membrane is driven to and fro by the sound-waves1 it naturally shakes the air in the cavity behind it1 and it also sets moving three most curious little bones4 ,the first of the bones is fastened to the middle of the drumhead so that it moves to and fro every time this membrane quivers4 ,the head of this bone fits into a hole in the next bone1 the anvil1 and is fastened to it by muscles1 so as to drag it along with it2 but1 the muscles being elastic1 it can draw back a little from the anvil1 and so give it a blow each time it comes back4 ,this anvil is in its turn very firmly fixed to the little bone1 shaped like a stirrup1 which you see at the end of the chain4 ,this stirrup rests upon a curious body which looks in the diagram like a snail-shell with tubes coming out of it4 ,this body1 which is called the labyrinth1 is made of bone1 but it has two little windows in it1 one covered only by a membrane1 while the other has the head of the stirrup resting upon it4 ,now1 with a little attention you will understand that when the air in the canal shakes the drumhead to and fro1 this membrane must drag with it the hammer1 the anvil1 and the stirrup4 ,each time the drum goes in1 the hammer will hit the anvil1 and drive the stirrup against the little window2 every time it goes out it will draw the hammer1 the anvil1 and the stirrup out again1 ready for another blow4 ,thus the stirrup is always playing upon this little window4 ,meanwhile1 inside the bony labyrinth there is a fluid like water1 and along the little passages are very fine hairs1 which wave to and fro like reeds2 and whenever the stirrup hits at the little window1 the fluid moves these hairs to and fro1 and they irritate the ends of a nerve1 and this nerve carries the message to your brain4 ,there are also some curious little stones called otoliths1 lying in some parts of this fluid1 and they1 by their rolling to and fro1 probably keep up the motion and prolong the sound4 ,you must not imagine we have explained here the many intricacies which occur in the ear2 ,i can only hope to give you a rough idea of it1 so that you may picture to yourselves the air-waves moving backwards and forward in the canal of your ear1 then the tympanum vibrating to and fro1 the hammer hitting the anvil1 the stirrup knocking at the little window1 the fluid waving the fine hairs and rolling the tiny stones1 the ends of the nerve quivering1 and then 7how we know not7 the brain hearing the message4 ,is not this wonderful1 going on as it does at every sound you hear8 ,and yet his is not all1 for inside that curled part of the labyrinth1 which looks like a snail-shell and is called the cochlea1 there is a most wonderful apparatus of more than three thousand fine stretched filaments or threads1 and these act like the strings of a harp1 and make you hear different tones4 ,if you go near to a harp or a piano1 and sing any particular note very loudly1 you will hear this note sounding in the instrument1 because you will set just that particular string quivering1 which gives the note you sang4 ,the air-waves set going by your voice touch that string1 because it can quiver in time with them1 while none of the other strings can do so4 ,now1 just in the same way the tiny instrument of three thousand strings in your ear1 which is called ,corti's organ1 vibrates to the air-waves1 one thread to one set of waves1 and another to another1 and according to the fibre that quivers1 will be the sound you hear4 ,here then at last1 we see how nature speaks to us4 ,all the movements going on outside1 however violent and varied they may be1 cannot of themselves make sound4 ,but here1 in the little space behind the drum of our ear1 the air-waves are sorted and sent on to our brain1 where they speak to us as sound4 ,week #ah ,but why then do we not hear all sounds as music8 ,why are some mere noise1 and others clear musical notes8 ,this depends entirely upon whether the sound-waves come quickly and regularly1 or by an irregular succession of shocks4 ,for example1 when a load of stones is being shot out of a cart1 you hear only a long1 continuous noise1 because the stones fall irregularly1 some quicker1 some slower1 here a number together1 and there two or three stragglers by themselves2 each of these different shocks comes to your ear and makes a confused1 noisy sound4 ,but if you run a stick very quickly along a paling1 you will hear a sound very like a musical not4 ,this is because the rods of the paling are all at equal distances one from another1 and so the shocks fall quickly one after another at regular intervals upon your ear4 ,any quick and regular succession of sounds makes a note1 even though it may be an ugly one4 ,the squeak of a slate pencil along a slate1 and the shriek of a railway whistle are not pleasant1 but they are real notes which you could copy on a violin4 ,i have here a simple apparatus which ,i have had made to show you that rapid and regular shocks produce a natural musical note4 ,this wheel 7,fig4 #cd7 is milled at the edge like a shilling1 and when ,i turn it rapidly so that it strikes against the edge of the card fixed behind it1 the notches strike in rapid succession1 and produce a musical sound4 ,we can also prove by this experiment that the quicker the blows are1 the higher the note will be4 ,i pull the string gently at first1 and then quicker and quicker1 and you will notice that the note grows sharper and sharper1 till the movement begins to slacken1 when the note goes down again4 ,this is because the more rapidly the air is hit1 the shorter are the waves it makes1 and short waves give a high note4 ,let us examine this with two tuning-forks4 ,i strike one1 and it sounds ,d1 the third space in the treble2 ,i strike the other1 and it sounds ,g1 the first leger line1 five notes above the ,c4 ,i have drawn on this diagram 7,fig4 #ce71 an imaginary picture of these two sets of waves4 ,you see that the ,g fork makes three waves1 while the ,c fork makes only two4 ,why is this8 ,because the prong of the ,g fork moves three times backwards and forwards while the prong of the ,c fork only moves twice2 therefore the ,g fork does not crowd so many atoms together before it draws back1 and the waves are shorter4 ,these two notes1 ,c and ,g1 are a fifth of an octave apart2 if we had two forks1 of which one went twice as fast as the other1 making four waves while the other made two1 then that note would be an octave higher4 ,so we see that all the sounds we hear1 - the warning noises which keep us from harm1 the beautiful musical notes with all the tunes and harmonies that delight us1 even the power of hearing the voices of those we love1 and learning from one another that which each can tell1 - all these depend upon the invisible waves of air1 even as the pleasures of light depend on the waves of ether4 ,it is by these sound-waves that nature speaks to us1 and in all her movements there is a reason why her boice is sharp or tender1 loud or gentle1 awful or loving4 ,take for instance the brook we spoke of at the beginning of the lecture4 ,why does it sing so sweetly1 while the wide deep river makes no noise8 ,because the little brook eddies and purls round the stones1 hitting them as it passes2 sometimes the water falls down a large stone1 and strikes against the water below2 or sometimes it grates the little pebbles together as they lie in its bed4 ,each of these blows makes a small globe of sound-waves1 which spread and spread till they fall on your ear1 and because they fall quickly and regularly1 they make a low1 musical note4 ,we might almost fancy that the brook wished to show how joyfully it flows along1 recalling ,shelley's beautiful lines3- ,sometimes it fell ,among the moss with hollow harmony1 ,dark and profound2 now on the polished stones ,it danced2 like childhood laughing as it went4 ,the broad deep river1 on the contrary1 makes none of these cascades and commotions4 ,the only places against which it rubs are the banks and the bottom2 and here you can sometimes hear it grating the particles of sand against each other if you listen very carefully4 ,but there is another reason why falling water makes a sound1 and often even a loud roaring noise in the cataract and in the breaking waves of the sea4 ,you do not only hear the water dashing against the rocky ledges or on the beach1 you also hear the bursting of innumerable little bladders of air which are contained in the water4 ,as each of these bladders is dashed on the ground1 it explodes and sends sound-waves to your ear4 ,listen to the sea some day when the waves are high and stormy1 and you cannot fail to be struck by the irregular bursts of sound4 ,the waves1 however1 do not only roar as they dash on the ground2 have you never noticed how they seem to scream as they draw back down the beach8 ,tennyson calls it1 ,the scream of the madden'd beach dragged down by the wave2 and it is caused by the stones grating against each other as the waves drag them down4 ,dr4 ,tyndall tells us that it is possible to know the size of the stones by the kind of noise they make4 ,if they are large1 it is a confused noise1 when smaller1 a kind of scream2 while a gravelly beach will produce a mere hiss4 ,who could be dull by the side of a brook1 a waterfall1 or the sea1 while he can listen for sounds like these1 and picture to himself how they are being made8 ,you may discover a number of other causes of sound made by water1 if you once pay attention to them4 ,nor is it only water that sings to us4 ,listen to the wind1 how sweetly it sighs among the leaves4 ,there we hear it1 because it rubs the leaves together1 and they produce the sound-waves4 ,but walk against the wind some day and you can hear it whistling in your own ear1 striking against the curved cup1 and then setting up a succession of waves in the hearing canal of the ear itself4 ,why should it sound in one particular tone when all kinds of sound-waves must be surging about in the disturbed air8 ,this glass jar will answer our question roughly4 ,if ,i strike my tuning-fork and hold it over the jar1 you cannot hear it1 because the sound is feeble1 but if ,i fill the jar gently with water1 when the water rises to a certain point you will hear a loud clear note1 because the waves of air in the jar are exactly the right length to answer to the note of the fork4 ,if ,i now blow across the mouth of the jar you hear the same note1 showing that a cavity of a particular length will only sound to the waves which fit it4 do you see now the reason why pan-pipes give different sounds1 or even the hole at the end of a common key when you blow across it8 ,here is a subject you will find very interesting if you will read about it1 for ,i can only just suggest it to you here4 ,but now you will see that the canal of your ear also answers only to certain waves1 and so the wind sings in your ear with a real if not a musical note4 ,again1 on a windy night have you not heard the wind sounding a wild1 sad note down a valley8 ,why do you think it sounds so much louder and more musical here than when it is blowing across the plain8 ,because air in the valley will only answer to a certain set of waves1 and1 like the pan-pipe1 gives a particular note as the wind blows across it1 and these waves go up and down the valley in regular pulses1 making a wild howl4 ,you may hear the same in the chimney1 or in the keyhole2 all these are waves set up in the hole across which the wind blows4 ,even the music in the shell which you hold to your ear is made by the air in the shell pulsating to and fro4 ,and how do you think it is set going8 ,by the throbbing of the veins in your own ear1 which causes the air in the shell to vibrate4 ,another grand voice of nature is the thunder4 ,people often have a vague idea that thunder is produced by the clouds knocking together1 which is very absurd1 if you remember that clouds are but water-dust4 ,the most probable explanation of thunder is much more beautiful than this4 ,you will remember from ,lecture ,,iii that heat forces the air-atoms apart4 ,now1 when a flash of lightning crosses the sky it suddenly expands the air all round it as it passes1 so that globe after globe of sound-waves is formed at every point across which the lightning travels4 ,now light1 you remember1 travels so wonderfully rapidly 7#aib1jjj miles in a second7 that a flash of lightning is seen by us and is over in a second1 even when it is two or three miles long4 ,but sound comes slowly1 taking five seconds to travel half a mile1 and so all the sound-waves at each point of the two or three miles fall on our ear one after the other1 and make the rolling thunder4 ,sometimes the roll is made even longer by the echo1 as the sound-waves are reflected to and fro by the clouds on their road2 and in the mountains we know how the peals echo and re-echo till they die away4 ,we might fill up far more than an hour in speaking of those voices which come to us as nature is at work4 ,think of the patter of the rain1 how each drop as it hits the pavement sends circles of sound-waves out on all sides2 or the loud report which falls on the ear of the ,alpine traveller as the glacier cracks on its way down the valley2 or the mighty boom of the avalanche as the snow slides in huge masses off the side of the lofty mountain4 ,each and all of these create their sound-waves1 large or small1 loud or feeble1 which make their way to your ear1 and become converted into sound4 ,we have1 however1 only time now just to glance at life-sounds1 of which there are so many around us4 ,do you know why we hear a buzzing1 as the gnat1 the bee1 or the cockchafer fly past8 ,not by the beating of their wings against the air1 as many people imagine1 and as is really the case with humming birds1 but by the scraping of the under-part of their hard wings against the edges of their hind legs1 which are toothed like a saw4 ,the more rapidly their wings move the stronger the grating sound becomes1 and you will now see why in hot1 thirsty weather the buzzing of the gnat is so loud1 for the more thirsty and the more eager he becomes1 the wilder his movements will be4 ,some insects1 like the drone-fly 7,eristalis tenax71 force the air through the tiny air-passages in their sides1 and as these passages are closed by little plates1 the plates vibrate to and fro and make sound-waves4 ,again1 what are those curious sounds you may hear sometimes if you rest your head on a trunk in the forest8 ,they are made by the timber-boring beetles1 which saw the wood with their jaws and make a noise in the world1 even though they have no voice4 ,all these life-sounds are made by creatures which do not sing or speak2 but the sweetest sounds of all in the woods are the voices of the birds4 ,all voice-sounds are made by two elastic bands or cushions1 called vocal chords1 stretched across the end of the tube or windpipe through which we breathe1 and as we send the air through them we tighten or loosen them as we will1 and so make them vibrate quickly or slowly and make sound-waves of different lengths4 ,but if you will try some day in the woods you will find that a bird can beat you over and over again in the length of his note2 when you are out of breath and forced to stop he will go on with his merry trill as fresh and clear as if he had only just begun4 ,this is because birds can draw air into the whole of their body1 and they have a large stock laid up in the folds of their windpipe1 and besides this the air-chamber behind their elastic bands or vocal chords has two compartments where we have only one1 and the second compartment has special muscles by which they can open and shut it1 and so prolong the trill4 ,only think what a rapid succession of waves must quiver through the air as a tiny lark agitates his little throat and pours forth a volume of song6 ,the next time you are in the country in the spring1 spend half an hour listening to him1 and try and picture to yourself how that little being is moving all the atmosphere round him4 ,then dream for a little while about sound1 what it is1 how marvellously it works outside in the world1 and inside in your ear and brain2 and then1 when you go back to work again1 you will hardly deny that it is well worth while to listen sometimes to the voices of nature and ponder how it is that we hear them4 ,week #ai ,,lecture ,,vii ,,the ,,life ,,of ,a ,,primrose ,when the dreary days of winter and the early damp days of spring are passing away1 and the warm bright sunshine has begun to pour down upon the grassy paths of the wood1 who does not love to go out and bring home posies of violets1 and bluebells1 and primroses8 ,we wander from one plant to another picking a flower here and a bud there1 as they nestle among the green leaves1 and we make our rooms sweet and gay with the tender and lovely blossoms4 ,but tell me1 did you ever stop to think1 as you added flower after flower to your nosegay1 how the plants which bear them have been building up their green leaves and their fragile buds during the last few weeks8 ,if you had visited the same spot a month before1 a few 7of7 last year's leaves1 withered and dead1 would have been all that you would have found4 ,and now the whole wood is carpeted with delicate green leaves1 with nodding bluebells1 and pale-yellow primroses1 as if a fairy had touched the ground and covered it with fresh young life4 ,and our fairies have been at work here2 the fairy ,life1 of whom we know so little1 though we love her so well and rejoice in the beautiful forms she can produce2 the fairy sunbeams with their invisible influence kissing the tiny shoots and warming them into vigour and activity2 the gentle rain-drops1 the balmy air1 all these have been working1 while you or ,i passed heedlessly by2 and now we come and gather the flowers they have made1 and too often forget to wonder how these lovely forms have sprung up around us4 ,our work during the next hour will be to consider this question4 ,you were asked last week to bring with you to-day a primrose- flower1 or a whole plant if possible1 in order the better to follow out with me the ,life of a ,primrose4 7,to enjoy this lecture1 the reader ought to have1 if possible1 a primrose- flower1 an almond soaked for a few minutes in hot water1 and a piece of orange47 ,this is a very different kind of subject from those of our former lectures4 ,there we took world- wide histories2 we travelled up to the sun1 or round the earth1 or into the air2 now ,i only ask you to fix your attention on one little plant1 and inquire into its history4 ,there is a beautiful little poem by ,tennyson1 which says - ,flower in the crannied wall1 ,i pluck you out of the crannies2 ,hold you here1 root and all1 in my hand1 ,little flower2 but if ,i could understand ,what you are1 root and all1 and all in all1 ,i should know what ,god and man is4 ,we cannot learn all about this little flower1 but we can learn enough to understand that it has a real separate life of its own1 well worth knowing4 ,for a plant is born1 breathes1 sleeps1 feeds1 and digests just as truly as an animal does1 though in a different way4 ,it works hard both for itself to get its food1 and for others in making the air pure and fit for animals to breathe4 ,it often lays by provision for the winter4 ,it sends young plants out1 as parents send their children1 to fight for themselves in the world2 and then1 after living sometimes to a good old age1 it dies1 and leaves its place to others4 ,we will try to follow out something of this life to-day2 and first1 we will begin with the seed4 ,i have here a packet of primrose-seeds1 but they are so small that we cannot examine them2 so ,i have also had given to each one of you an almond-kernel1 which is the seed of the almond- tree1 and which has been soaked1 so that it splits in half easily4 ,from this we can learn about seeds in general1 and then apply it to the primrose4 ,if you peel the two skins off your almond-seed 7the thick1 brown1 outside skin1 and the thin1 transparent one under it71 the two halves of the almond will slip apart quite easily4 ,one of these halves will have a small dent at the pointed end1 while in the other half you will see a little lump1 which fitted into the dent when the two halves were joined4 ,this little lump 7a b1 ,fig4 #cg7 is a young plant1 and the two halves of the almond are the seed leaves which hold the plantlet1 and feed it till it can feed itself4 ,the rounded end of the plantlet 7b7 sticking out of the almond1 is the beginning of the root1 while the other end 7a7 will in time become the stem4 ,if you look carefully1 you will see two little points at this end1 which are the tips of future leaves4 ,only think how minute this plantlet must be in a primrose1 where the whole seed is scarcely larger than a grain of sand6 ,yet in this tiny plantlet lies hid the life of the future plant4 ,when a seed falls into the ground1 so long as the earth is cold and dry1 it lies like a person in a trance1 as if it were dead2 but as soon as the warm1 damp spring comes1 and the busy little sun-waves pierce down into the earth1 they wake up the plantlet and make it bestir itself4 ,they agitate to and fro the particles of matter in this tiny body1 and cause them to seek out for other particles to seize and join to themselves4 ,but these new particles cannot come in at the roots1 for the seed has none2 nor through the leaves1 for they have not yet grown up2 and so the plantlet begins by helping itself to the store of food laid up in the thick seed-leaves in which it is buried4 ,here it finds starch1 oils1 sugar1 and substances called albuminoids1 -- the sticky matter which you notice in wheat-grains when you chew them is one of the albuminoids4 ,this food is all ready for the plantlet to use1 and it sucks it in1 and works itself into a young plant with tiny roots at one end1 and a growing shoot1 with leaves1 at the other4 ,but how does it grow8 ,what makes it become larger8 ,to answer this you must look at the second thing ,i asked you to bring - a piece of orange4 ,if you take the skin off a piece of orange1 you will see inside a number of long-shaped transparent bags1 full of juice4 ,these we call cells1 and the flesh of all plants and animals is made up of cells like these1 only of various shapes4 ,in the pith of elder they are round1 large1 and easily seen 7a1 ,fig4 #ci72 in the stalks of plants they are long1 and lap over each other 7b1 ,fig4 #ci71 so as to give the stalk strength to stand upright4 ,sometimes many cells growing one on the top of the other break into one tube and make vessels4 ,but whether large or small1 they are all bags growing one against the other4 ,in the orange-pulp these cells contain only sweet juice1 but in other parts of the orange-tree or any other plant they contain a sticky substance with little grains in it4 ,this substance is called protoplasm1 or the first form of life1 for it is alive and active1 and under a microscope you may see in a living plant streams of the little grains moving about in the cells4 ,now we are prepared to explain how our plant grows4 ,imagine the tiny primrose plantlet to be made up of cells filled with active living protoplasm1 which drinks in starch and other food from the seed-leaves4 ,in this way each cell will grow too full for its skin1 and then the protoplasm divides into two parts and builds up a wall between them1 and so one cell becomes two4 ,each of these two cells again breaks up into two more1 and so the plant grows larger and larger1 till by the time it has used up all the food in the seed-leaves1 it has sent roots covered with fine hairs downwards into the earth1 and a shoot with beginnings of leaves up into the air4 ,sometimes the seed-leaves themselves come above the ground1 as in the mustard-plant1 and sometimes they are left empty behind1 while the plantlet shoots through them4 ,and now the plant can no longer afford to be idle and live on prepared food4 ,it must work for itself4 ,until now it has been taking in the same kind of food that you and ,i do2 for we too find many seeds very pleasant to eat and useful to nourish us4 ,but now this store is exhausted4 ,upon what then is the plant to live8 ,it is cleverer than we are in this1 for while we cannot live unless we have food which has once been alive1 plants can feed upon gases and water and mineral matter only4 ,think over the substances you can eat or drink1 and you will find they are nearly all made of things which have been alive3 meat1 vegetables1 bread1 beer1 wine1 milk2 all these are made from living matter1 and though you do take in such things as water and salt1 and even iron and phosphorus1 these would be quite useless if you did not eat and drink prepared food which your body can work into living matter4 ,but the plant as soon as it has roots and leaves begins to make living matter out of matter that has never been alive4 ,through all the little hairs of its roots it sucks in water1 and in this water are dissolved more or less of the salts of ammonia1 phosphorus1 sulphur1 iron1 lime1 magnesia1 and even silica1 or flint4 ,in all kinds of earth there is some iron1 and we shall see presently that this is very important to the plant4 ,suppose1 then1 that our primrose has begun to drink in water at its roots4 ,how is it to get this water up into the stem and leaves1 seeing that the whole plant is made of closed bags or cells8 ,it does it in a very curious way1 which you can prove for yourselves4 ,whenever two fluids1 one thicker than the other1 such as treacle and water for example1 are only separated by a skin or any porous substance1 they will always mix1 the thinner one oozing through the skin into the thicker one4 ,if you tie a piece of bladder over a glass tube1 fill the tube half-full of treacle1 and then let the covered end rest in a bottle of water1 in a few hours the water will get in to the treacle and the mixture will rise up in the tube till it flows over the top4 ,now1 the saps and juices of plants are thicker than water1 so1 directly the water enters the cells at the root it oozes up into the cells above1 and mixes with the sap4 ,then the matter in those cells becomes thinner than in the cells above1 so it too oozes up1 and in this way cell by cell the water is pumped up into the leaves4 ,when it gets there it finds our old friends the sun-beams hard at work4 ,if you have ever tried to grow a plant in a cellar1 you will know that in the dark its leaves remain white and sickly4 ,it is only in the sunlight that a beautiful delicate green tint is given to them1 and you will remember from ,lecture ,,ii4 that this green tint shows that the leaf has used all the sun-waves except those which make you see green2 but why should it do this only when it has grown up in the sunshine8 ,the reason is this3 when the sunbeam darts into the leaf and sets all its particles quivering1 it divides the protoplasm into two kinds1 collected into different cells4 ,one of these remains white1 but the other kind1 near the surface1 is altered by the sunlight and by the help of the iron brought in by the water4 ,this particular kind of protoplasm1 which is called chlorophyll1 will have nothing to do with the green waves and throws them back1 so that every little grain of this protoplasm looks green and gives the leaf its green colour4 ,it is these little green cells that by the help of the sun-waves digest the food of the plant and turn the water and gases into useful sap and juices4 ,we saw in ,lecture ,,iii4 that when we breathe-in air1 we use up the oxygen in it and send back out of our mouths carbonic acid1 which is a gas made of oxygen and carbon4 ,now1 every living things wants carbon to feed upon1 but plants cannot take it in by itself1 because carbon is solid 7the blacklead in your pencils is pure carbon71 and a plant cannot eat1 it can only drink-in fluids and gases4 ,here the little green cells help it out of its difficulty4 ,they take in or absorb out of the air carbonic acid gas which we have given out of our mouths and then by the help of the sun-waves they tear the carbon and oxygen apart4 ,most of the oxygen they throw back into the air for us to use1 but the carbon they keep4 ,if you will take some fresh laurel-leaves and put them into a tumbler of water turned upside-down in a saucer of water1 and set the tumbler in the sunshine1 you will soon see little bright bubbles rising up and clinging to the glass4 ,these are bubbles of oxygen gas1 and they tell you that they have been set free by the green cells which have torn from them the carbon of the carbonic acid in the water4 ,but what becomes of the carbon8 ,and what use is made of the water which we have kept waiting all this time in the leaves8 ,water1 you already know1 is made of hydrogen and oxygen1 but perhaps you will be surprised when ,i tell you that starch1 sugar1 and oil1 which we get from plants1 are nothing more than hydrogen and oxygen in different quantities joined to carbon4 ,it is very difficult at first to picture such a black thing as carbon making part of delicate leaves and beautiful flowers1 and still more of pure white sugar4 ,but we can make an experiment by which we can draw the hydrogen and oxygen out of common loaf sugar1 and then you will see the carbon stand out in all its blackness4 ,i have here a plate with a heap of white sugar in it4 ,i pour upon it first some hot water to melt and warm it1 and then some strong sulphuric acid4 ,this acid does nothing more than simply draw the hydrogen and oxygen out4 ,see6 in a few moments a black mass of carbon begins to rise1 all of which has come out of the white sugar you saw just now4 997,the common dilute sulphuric acid of commerce is not strong enough for this experiment1 but pure sulphuric acid can be secured from any chemist4 ,great care must be taken in using it1 as it burns everything it touches47 ,you see1 then1 that from the whitest substance in plants we can get this black carbon2 and in truth1 one-half of the dry part of every plant is composed of it4 ,now look at my plant again1 and tell me if we have not already found a curious history8 ,fancy that you see the water creeping in at the roots1 oozing up from cell to cell till it reaches the leaves1 and there meeting the carbon which has just come out of the air1 and being worked up with it by the sun-waves into starch1 or sugar1 or oils4 ,but meanwhile1 how is new protoplasm to be formed8 for without this active substance none of the work can go on4 ,here comes into use a lazy gas we spoke of in ,lecture ,,iii4 ,there we thought that nitrogen was of no use except to float oxygen in the air1 but here we shall find it very useful4 ,so far1 as we know1 plants cannot take up nitrogen out of the air1 but they can get it out of the ammonia which the water brings in at their roots4 ,ammonia1 you will remember1 is a strong-smelling gas1 made of hydrogen and nitrogen1 and which is often almost stifling near a manure-heap4 ,when you manure a plant you help it to get this ammonia1 but at any time it gets some from the soil and also from the rain-drops which bring it down in the air4 ,out of this ammonia the plant takes the nitrogen and works it up with the three elements1 carbon1 oxygen1 and hydrogen1 to make the substances called albuminoids1 which form a large part of the food of the plant1 and it is these albuminoids which go to make protoplasm4 ,you will notice that while the starch and other substances are only made of three elements1 the active protoplasm is made of these three added to a fourth1 nitrogen1 and it also contains phosphorus and sulphur4 ,and so hour after hour and day after day our primrose goes on pumping up water and ammonia from its roots to its leaves1 drinking in carbonic acid from the air1 and using the sun-waves to work them all up into food to be sent to all parts of its body4 ,in this way these leaves act1 you see1 as the stomach of the plant1 and digest its food4 ,sometimes more water is drawn up into the leaves than can be used1 and then the leaf opens thousands of little mouths in the skin of its under surface1 which let the drops out just as drops of perspiration ooze through our skin when we are overheated4 ,these little mouths1 which are called stomates 7a1 ,fig4 #db7 are made of two flattened cells1 fitting against each other4 ,when the air is damp and the plant has too much water these lie open and let it out1 but when the air is dry1 and the plant wants to keep as much water as it can1 then they are closely shut4 ,there are as many as a hundred thousand of these mouths under one apple-leaf1 so you may imagine how small they often are4 ,plants which only live one year1 such as mignonette1 the sweet pea1 and the poppy1 take in just enough food to supply their daily wants and to make the seeds we shall speak of presently4 ,then1 as soon as their seeds are ripe their roots begin to shrivel1 and water is no longer carried up4 ,the green cells can no longer get food to digest1 and they themselves are broken up by the sunbeams and turn yellow1 and the plant dies4 ,but many plants are more industrious than the stock and mignonette1 and lay by store for another year1 and our primrose is one of these4 ,look at this thick solid mass below the primrose leaves1 out of which the roots spring4 7,see the plant in the foreground of the heading of the lecture47 ,this is really the stem of the primrose hidden underground1 and all the starch1 albuminoids1 c41 which the plant can spare as it grows1 are sent down into this underground stem and stored up there1 to lie quietly in the ground through the long winter1 and then when the warm spring comes this stem begins to send out leaves for a new plant4 ,week #ba ,we have now seen how a plant springs up1 feeds itself1 grows1 stores up food1 withers1 and dies2 but we have said nothing yet about its beautiful flowers or how it forms its seeds4 ,if we look down close to the bottom of the leaves in a primrose root in spring-time1 we shall always find three or four little green buds nestling in among the leaves1 and day by day we may see the stalk of these buds lengthening till they reach up into the open sunshine1 and then the flower opens and shows its beautiful pale- yellow crown4 ,we all know that seeds are formed in the flower1 and that the seeds are necessary to grow into new plants4 ,but do we know the history of how they are formed1 or what is the use of the different parts of the bud8 ,let us examine them all1 and then ,i think you will agree with me that this is not the least wonderful part of the plant4 ,remember that the seed is the one important thing and then notice how the flower protects it4 ,first1 look at the outside green covering1 which we call the calyx4 ,see how closely it fits in the bud1 so that no insects can creep in to gnaw the flower1 nor any harm come to it from cold or blight4 ,then1 when the calyx opens1 notice that the yellow leaves which form the crown or corolla1 are each alternate with one of the calyx leaves1 so that anything which got past the first covering would be stopped by the second4 ,lastly1 when the delicate corolla has opened out1 look at those curious yellow bags just at the top of the tube 7b1#b1 ,fig4 #dc74 ,what is their use8 ,but ,i fancy ,i see two or three little questioning faces which seem to say1 ,i see no yellow bags at the top of the tube4 ,well1 ,i cannot tell whether you can or not in the specimen you have in your hand2 for one of the most curious things about primrose flowers is1 that some of them have these yellow bags at the top of the tube and some of them hidden down right in the middle4 ,but this ,i can tell you3those of you who have got no yellow bags at the top will have a round knob there 7,i a1 ,fig4 #dc71 and will find the yellow bags 7b7 buried in the tube4 ,those1 on the other hand1 who have the yellow bags 7#b b1 ,fig4 #dc7 at the top will find the knob 7a7 half-way down the tube4 ,now for the use of these yellow bags1 which are called the anthers of the stamens1 the stalk on which they grow being called the filament or thread4 ,if you can manage to split them open you will find that they have a yellow powder in them1 called pollen1 the same as the powder which sticks to your nose when you put it into a lily2 and if you look with a magnifying glass at the little green knob in the centre of the flower1 you will probably see some of this yellow dust sticking on it 7,a1 ,fig4 #dc74 ,we will leave it there for a time1 and examine the body called the pistil1 to which the knob belongs4 ,pull off the yellow corolla 7which will come off quite easily71 and turn back the green leaves4 ,you will then see that the knob stands on the top of a column1 and at the bottom of this column there is a round ball 7s v71 which is a vessel for holding the seeds4 ,in this diagram 7,a1 ,fig4 #dc7 ,i have drawn the whole of this curious ball and column as if cut in half1 so that we may see what is in it4 ,in the middle of the ball1 in a cluster1 there are a number of round transparent little bodies1 looking something like round green orange-cells full of juice4 ,they are really cells full of protoplasm1 with one little dark spot in each of them1 which by-and-by is to make our little plantlet that we found in the seed4 ,these1 then1 are seeds1 you will say4 ,not yet2 they are only ovules1 or little bodies which may become seeds4 ,if they were left as they are they would all wither and die4 ,but those little grains of pollen1 which we saw sticking to the knob at the top1 are coming down to help them4 ,as soon as these yellow grains touch the sticky knob or stigma1 as it is called1 they throw out tubes1 which grow down the column until they reach the ovules4 ,in each one of these they find a tiny hole1 and into this they creep1 and then they pour into the ovule all the protoplasm from the pollen-grain which is sticking above1 and this enables it to grow into a real seed1 with a tiny plantlet inside4 ,this is how the plant forms its seed to bring up new little ones next year1 while the leaves and the roots are at work preparing the necessary food4 ,think sometimes when you walk in the woods1 how hard at work the little plants and big trees are1 all around you4 ,you breathe in the nice fresh oxygen they have been throwing out1 and little think that it is they who are making the country so fresh and pleasant1 and that while they look as if they were doing nothing but enjoying the bright sunshine1 they are really fulfilling their part in the world by the help of this sunshine2 earning their food from the ground working it up2 turning their leaves where they can best get light 7and in this it is chiefly the violet sun-waves that help them71 growing1 even at night1 by making new cells out of the food they have taken in the day2 storing up for the winter2 putting out their flowers and making their seeds1 and all the while smiling so pleasantly in quiet nooks and sunny dells that it makes us glad to see them4 ,but why should the primroses have such golden crowns8 plain green ones would protect the seed quite as well4 ,ah6 now we come to a secret well worth knowing4 ,look at the two primrose flowers1 #a and #b1 ,fig4 #dc1 p4 #afc1 and tell me how you think the dust gets on to the top of the sticky knob or stigma4 ,no4 #b seems easy enough to explain1 for it looks as if the pollen could fall down easily from the stamens on to the knob1 but it cannot fall up1 as it would have to do in ,no4 #a4 ,now the curious truth is1 as ,mr4 ,darwin has shown1 that neither of these flowers can get the dust easily for themselves1 but of the two ,no4 #a has the least difficulty4 ,look at a withered primrose1 and see how it holds its head down1 and after a little while the yellow crown falls off4 ,it is just about as it is falling that the anthers or bags of stamens burst open1 and then1 in ,no4 #a 7,fig4 #dd71 they are dragged over the knob and some of the grains stick there4 ,but in the other form of primrose1 ,no4 #b1 when the flower falls off1 the stamens do not come near the knob1 so it has no chance of getting any pollen2 and while the primrose is upright the tube is so narrow that the dust does not easily fall4 ,but1 as ,i have said1 neither kind gets it very easily1 nor is it good for them if they do4 ,the seeds are much stronger and better if the dust or pollen of one flower is carried away and left on the knob or stigma of another flower2 and the only way this can be done is by insects flying from one flower to another and carrying the dust on their legs and bodies4 ,if you suck the end of the tube of the primrose flower you will find it tastes sweet1 because a drop of honey has been lying there4 ,when the insects go in to get this honey1 they brush themselves against the yellow dust-bags1 and some of the dust sticks to them1 and then when they go to the next flower they rub it off on to its sticky knob4 ,look at ,no4 #a and ,no4 #b 7,fig4 #dc7 and you will see at once that if an insect goes into ,no4 #a and the pollen sticks to him1 when he goes into ,no4 #b just that part of his body on which the pollen is will touch the knob2 and so the flowers become what we call crossed1 that is1 the pollen-dust of the one feeds the ovule of the other4 ,and just the same thing will happen if he flies from ,no4 #b to ,no4 #a4 ,there the dust will be just in the position to touch the knob which sticks out of the flower4 ,therefore1 we can see clearly that it is good for the primrose that bees and other insects should come to it1 and anything it can do to entice them will be useful4 ,now1 do you not think that when an insect once knew that the pale-yellow crown showed where honey was to be found1 he would soon spy these crowns out as he flew along8 or if they were behind a hedge1 and he could not see them1 would not the sweet scent tell him where to come and look for them8 ,and so we see that the pretty sweet-scented corolla is not only delightful for us to look at and to smell1 but it is really very useful in helping the primrose to make strong healthy seeds out of which the young plants are to grow next year4 ,and now let us see what we have learnt4 ,we began with a tiny seed1 though we did not then know how this seed had been made4 ,we saw the plantlet buried in it1 and learnt how it fed at first on prepared food1 but soon began to make living matter for itself out of gases taken from the water through the cells to its stomach - the leaves6 ,and how marvellously the sun-waves entering there formed the little green granules1 and then helped them to make food and living protoplasm6 ,at this point we might have gone further1 and studied how the fibres and all the different vessels of the plant are formed1 and a wondrous history it would have been4 ,but it was too long for one hour's lecture1 and you must read it for yourselves in books on botany4 ,we had to pass on to the flower1 and learn the use of the covering leaves1 the gaily coloured crown attracting the insects1 the dust-bags holding the pollen1 the little ovules each with the germ of a new plantlet1 lying hidden in the seed- vessel1 waiting for the pollen-grains to grow down to them4 ,lastly1 when the pollen crept in at the tiny opening we learnt that the ovule had now all it wanted to grow into a perfect seed4 ,and so we came back to a primrose seed1 the point from which we started2 and we have a history of our primrose from its birth to the day when its leaves and flowers wither away and it dies down for the winter4 ,but what fairies are they which have been at work here8 ,first1 the busy little fairy ,life in the active protoplasm2 and secondly1 the sun-waves4 ,we have seen that it was by the help of the sunbeams that the green granules were made1 and the water1 carbonic acid1 and nitrogen worked up into the living plant4 ,and in doing this work the sun-waves were caught and their strength used up1 so that they could no longer quiver back into space4 ,but are they gone for ever8 ,so long as the leaves or the stem or the root of the plant remain they are gone1 but when those are destroyed we can get them back again4 ,take a handful of dry withered plants and light them with a match1 then as the leaves burn and are turned back again to carbonic acid1 nitrogen1 and water1 our sunbeams come back again in the flame and heat4 ,and the life of the plant8 ,what is it1 and why is this protoplasm always active and busy8 ,i cannot tell you4 ,study as we may1 the life of the tiny plant is as much a mystery as your life and mine4 ,it came1 like all things1 from the bosom of the ,great ,father1 but we cannot tell how it came nor what it is4 ,we can see the active grains moving under the microscope1 but we cannot see the power that moves them4 ,we only know it is a power given to the plant1 as to you and to me1 to enable it to live its life1 and to do its useful work in the world4 ,week #bb ,,lecture ,,viii ,,the ,,history ,,of ,a ,,piece ,,of ,,coal ,i have here a piece of coal 7,fig4 #de71 which1 though it has been cut with some care so as to have a smooth face1 is really in no other way different from any ordinary lump which you can pick for yourself out of the coal-scuttle4 ,our work to-day is to relate the history of this black lump2 to learn what it is1 what it has been1 and what it will be4 ,it looks uninteresting enough at first sight1 and yet if we examine it closely we shall find some questions to ask even about its appearance4 ,look at the smooth face of this specimen and see if you can explain those fine lines which run across so close together as to look like the edges of the leaves of a book4 ,try to break a piece of coal1 and you will find that it will split much more easily along those lines than across the other way of the lump2 and if you wish to light a fire quickly you should always put this lined face downwards so that the heat can force its way up through these cracks and gradually split up the block4 ,then again if you break the coal carefully along one of these lines you will find a fine film of charcoal lying in the crack1 and you will begin to suspect that this black coal must have been built up in very thin layers1 with a kind of black dust between them4 ,the next thing you will call to mind is that this coal burns and gives flame and heat1 and that this means that in some way sunbeams are imprisoned in it2 lastly1 this will lead you to think of plants1 and how they work up the strength of the sunbeams into their leaves1 and hide black carbon in even the purest and whitest substance they contain4 ,is coal made of burnt plants1 then8 ,not burnt ones1 for if so it would not burn again2 but you may have read how the makers of charcoal take wood and bake it without letting it burn1 and then it turns black and will afterwards make a very good fire2 and so you will see that it is probable that our piece of coal is made of plants which have been baked and altered1 but which have still much sunbeam strength bottled up in them1 which can be set free as they burn4 ,if you will take an imaginary journey with me to a coal-pit near ,newcastle1 which ,i visited many years ago1 you will see that we have very good evidence that coal is made of plants1 for in all coal-mines we find remains of them at every step we take4 ,let us imagine that we have put on old clothes which will not spoil1 and have stepped into the iron basket 7see ,fig4 #df7 called by the miners a cage1 and are being let down the shaft to the gallery where the miners are at work4 ,most of them will probably be in the gallery b1 because a great deal of the coal in a has been already taken out4 ,but we will stop in a because there we can see a great deal of the roof and the floor4 ,when we land on the floor of the gallery we shall find ourselves in a kind of tunnel with railway lines laid along it and trucks laden with coal coming towards the cage to be drawn up1 while empty ones are running back to be loaded where the miners are at work4 ,taking lamps in our hands and keeping out of the way of the trucks1 we will first throw the light on the roof1 which is made of shale or hardened clay4 ,we shall not have gone many yards before we see impressions of plants in the shale1 like those in this specimen 7,fig4 #dg71 which was taken out of a coal-mine at ,neath in ,glamorganshire1 a few days ago1 and sent up for this lecture4 ,you will recognize at once the marks of ferns 7a71 for they look like those you gather in the hedges of an ordinary country lane1 and that long striped branch 7b7 does not look unlike a reed1 and indeed it is something of this kind1 as we shall see by-and-by4 ,you will find plenty of these impressions of plants as you go along the gallery and look up at the roof1 and with them there will be others with spotted stems1 or with stems having a curious diamond pattern upon them1 and many ferns of various kinds4 ,next look down at your feet and examine the floor4 ,you will not have to search long before you will almost certainly find a piece of stone like that represented in ,fig4 #dh1 which has also come from ,neath ,colliery4 ,this fossil1 which is the cast of a piece of a plant1 puzzled those who found it for a very long time4 ,at last1 however1 ,mr4 ,binney found the specimen growing to the bottom of the trunk of one of the fossil trees with spotted stems1 called ,sigillaria2 and so proved that this curious pitted stone is a piece of fossil root1 or rather underground stem1 like that which we found in the primrose1 and that the little pits or dents in it are scars where the rootlets once were given off4 ,whole masses of these root-stems1 with ribbon-like roots lying scattered near them1 are found buried in the layer of clay called the underclay which makes the floor of the coal1 and they prove to us that this underclay must have been once the ground in which the roots of the coal-plants grew4 ,you will feel still more sure of this when you find that there is not only one straight gallery of coal1 but that galleries branch out right and left1 and that everywhere you find the coal lying like a sandwich between the floor and the roof1 showing that quite a large piece of country must be covered by these remains of plants all rooted in the underclay4 ,but how about the coal itself8 ,it seems likely1 when we find roots below and leaves and stems above1 that the middle is made of plants1 but can we prove it8 ,we shall see presently that it has been so crushed and altered by being buried deep in the ground that the traces of leaves have almost been destroyed1 though people who are used to examining with the microscope1 can see the crushed remains of plants in thin slices of coal4 ,but fortunately for us1 perfect pieces of plants have been preserved even in the coal-bed itself4 ,do you remember our learning in ,lecture ,,iv1 that water with lime in it petrifies things1 that is1 leaves carbonate of lime to fill up grain by grain the fibres of an animal or plant as the living matter decays1 and so keeps an exact representation of the object8 ,now1 it so happens that in a coal-bed at ,south ,ouram1 near ,halifax1 as well as in some other places1 carbonate of lime trickled in before the plants were turned into coal1 and made some round nodules in the plant-bed1 which look like cannon- balls4 ,afterwards1 when all the rest of the bed was turned into coal1 these round balls remained crystallized1 and by cutting thin transparent slices across the nodule we can distinctly see the leaves and stems and curious little round bodies which make up the coal4 ,several such sections may be seen at the ,british ,museum1 and when we compare these fragments of plants with those which we find above and below the coal-bed1 we find that they agree1 thus proving that coal is made of plants1 and of those plants whose roots grew in the clay floor1 while their heads reached up far above where the roof now is4 ,the next question is1 what kind of plants were these8 ,have we anything like them living in the world now8 ,you might perhaps think that it would be impossible to decide this question from mere petrified pieces of plants4 ,but many men have spent their whole lives in deciphering all the fragments that could be found1 and though the section given in ,fig4 #di may look to you quite incomprehensible1 yet a botanist can reed it as we read a book4 ,for example1 at ,s and ,l1 where stems are cut across1 he can learn exactly how they were build up inside1 and compare them with the stems of living plants1 while the fruits cc and the little round spores lying near them1 tell him their history as well as if he had gathered them from the tree4 ,in this way we have learnt to know very fairly what the plants of the coal were like1 and you will be surprised when ,i tell you that the huge trees of the coal-forests1 of which we sometimes find trunks in the coal-mines from ten to fifty feet long1 are only represented on the earth now by small insignificant plants1 scarcely ever more than two feet1 and often not many inches high4 ,have you ever seen the little club moss or ,lycopodium which grows all over ,england1 but chiefly in the north1 on heaths and mountains8 ,at the end of each of its branches it bears a cone made of scaly leaves2 and fixed to the inside of each of these leaves is a case called a sporangium1 full of little spores or moss-seeds1 as we may call them1 though they are not exactly like true seeds4 ,in one of these club-mosses called ,selaginella1 the cases near the bottom of the cone contain large spores1 while those near the top contain a powdery dust4 ,these spores are full of resin1 and they are collected on the ,continent for making artificial lightning in the theatres1 because they flare when lighted4 ,now this little ,selaginella is of all living plants the one most like some of the gigantic trees of the coal-forests4 ,if you look at this picture of a coal-forest 7,fig4 #ea71 you will find it difficult perhaps to believe that those great trees1 with diamond markings all up the trunk1 hanging over from the right to the left of the picture1 and covering all the top with their boughs1 could be in any way relations of the little ,selaginella2 yet we find branches of them in the beds above the coal1 bearing cones larger but just like ,selaginella cones2 and what is most curious1 the spores in these cones are of exactly the same kind and not any larger than those of the club-mosses4 ,these trees are called by botanists ,lepidodendrons1 or scaly trees2 there are numbers of them in all coal-mines1 and one trunk has been found #di feet long4 ,their branches were divided in a curious forked manner and bore cones at the ends4 ,the spores which fell from these cones are found flattened in the coal1 and they may be seen scattered about in the coal-ball4 ,week #bc ,another famous tree which grew in the coal-forests was the one whose roots we found in the floor or underclay of the coal4 ,it has been called ,sigillaria1 because it has marks like seals 7sigillum1 a seal7 all up the trunk1 due to the scars left by the leaves when they fell from the tree4 ,you will see the ,sigillarias on the left-hand side of the coal-forest picture1 having those curious tufts of leaves springing out of them at the top4 ,their stems make up a great deal of the coal1 and the bark of their trunks is often found in the clays above1 squeezed flat in lengths of #cj1 #fj1 or #gj feet4 ,sometimes1 instead of being flat the bark is still in the shape of a trunk1 and the interior is filled with sane2 and then the trunk is very heavy1 and if the miners do not prop the roof up well it falls down and kills those beneath it4 ,stigmaria is the root of the ,sigillaria1 and is found in the clays below the coal4 ,botanists are not yet quite certain about the seed-cases of this tree1 but ,mr4 ,carruthers believes that they grew inside the base of the leaves1 as they do in the quillwort1 a small plant which grows at the bottom of our mountain lakes4 ,but what is that curious reed-like stem we found in the piece of shale 7see ,fig4 #dg78 ,that stem is very important1 for it belonged to a plant called a ,calamite1 which1 as we shall see presently1 helped to sift the earth away from the coal and keep it pure4 ,this plant was a near relation of the horsetail1 or ,equisetum1 which grows in our marshes2 only1 just as in the case of the other trees1 it was enormously larger1 being often #bj feet high1 whereas the little ,equisetum1 ,fig4 #eb1 is seldom more than a foot1 and never more than #d feet high in ,england1 though in tropical ,south ,america they are much higher4 ,still1 if you have ever gathered horsetails1 you will see at once that those trees in the foreground of the picture 7,fig4 #ea71 with leaves arranged in stars round the branches1 are only larger copies of the little marsh-plants2 and the seed-vessels of the two plants are almost exactly the same4 ,these great trees1 the ,lepidodendrons1 the ,sigillarias1 and the ,calamites1 together with large tree-ferns1 are the chief plants that we know of in the coal-forests4 ,it seems very strange at first that they should have been so large when their descendants are now so small1 but if you look at our chief plants and trees now1 you will find that nearly all of them bear flowers1 and this is a great advantage to them1 because it tempts the insects to bring them the pollen-dust1 as we saw in the last lecture4 ,now the ,lipidodendrons and their companions had no true flowers1 but only these seed-cases which we have mentioned2 but as there were no flowering plants in their time1 and they had the ground all to themselves1 they grew fine and large4 ,by-and-by1 however1 when the flowering plants came in1 these began to crowd out the old giants of the coal-forests1 so that they dwindled and dwindled from century to century till their great-great- grandchildren1 thousands of generations after1 only lift up their tiny heads in marshes and on heaths1 and tell us that they were big once upon a time4 ,and indeed they must have been magnificent in those olden days1 when they grew thick and tall in the lonely marshes where plants and trees were the chief inhabitants4 ,we find no traces in the clay-beds of the coal to lead us to suppose that men lived in those days1 nor lions1 nor tigers1 nor even birds to fly among the trees2 but these grand forests were almost silent1 except when a huge animal something like a gigantic newt or frog went croaking through the marsh1 or a kind of grasshopper chirruped on the land4 ,but these forms of life were few and far between1 compared to the huge trees and tangled masses of ferns and reeds which covered the whole ground1 or were reflected in the bosom of the large pools and lakes round about which they grew4 ,and now1 if you have some idea of the plants and trees of the coal1 it is time to ask how these plants became buried in the earth and made pure coal1 instead of decaying away and leaving behind only a mixture of earth and leaves8 ,to answer this question1 ,i must ask you to take another journey with me across the ,atlantic to the shores of ,america1 and to land at ,norfolk in ,virginia1 because there we can see a state of things something like the marshes of the coal-forests4 ,all round about ,norfolk the land is low1 flat1 and marshy1 and to the south of the town1 stretching far away into ,north ,carolina1 is a large1 desolate swamp1 no less than forty miles long and twenty-five broad4 ,the whole place is one enormous quagmire1 overgrown with water-plants and trees4 ,the soil is as black as ink from the old1 dead leaves1 grasses1 roots1 and stems which lie in it2 and so soft1 that everything would sink into it1 if it were not for the matted roots of the mosses1 ferns1 and other plants which bind it together4 ,you may dig down for ten or fifteen feet1 and find nothing but peat made of the remains of plants which have lived and died there in succession for ages and ages1 while the black trunks of the fallen trees lie here and there1 gradually being covered up by the dead plants4 ,the whole place is so still1 gloomy1 and desolate1 that it goes by the name of the ,great ,dismal ,swamp1 and you see we have here what might well be the beginning of a bed of coal2 for we know that peat when dried becomes firm and makes an excellent fire1 and that if it were pressed till it was hard and solid it would not be unlike coal4 ,if1 then1 we can explain how this peaty bed has been kept pure from earth1 we shall be able to understand how a coal-bed may have been formed1 even though the plants and trees which grow in this swamp are different from those which grew in the coal-forests4 ,the explanation is not difficult2 streams flow constantly1 or rather ooze into the ,great ,dismal ,swamp from the land that lies to the west1 but instead of bringing mud in with them as rivers bring to the sea1 they bring only clear1 pure water1 because1 as they filter for miles through the dense jungle of reeds1 ferns1 and shrubs which grow round the marsh1 all the earth is sifted out and left behind4 ,in this way the spongy mass of dead plants remains free from earthy grains1 while the water and the shade of the thick forest of trees prevent the leaves1 stems1 etc41 from being decomposed by the air and sun4 ,and so year after year as the plants die they leave their remains for other plants to take root in1 and the peaty mass grows thicker and thicker1 while tall cedar trees and evergreens live and die in these vast1 swampy forests1 and being in loose ground are easily blown down by the wind1 and leave their trunks to be covered up by the growing moss and weeds4 ,now we know that there were plenty of ferns and of large ,calamites growing thickly together in the coal-forests1 for we find their remains everywhere in the clay1 so we can easily picture to ourselves how the dense jungle formed by these plants would fringe the coal-swamp1 as the present plants do the ,great ,dismal ,swamp1 and would keep out all earthy matter1 so that year after year the plants would die and form a thick bed of peat1 afterwards to become coal4 ,week #bd ,the next thing we have to account for is the bed of shale or hardened clay covering over the coal4 ,now we know that from time to time land has gone slowly up and down on our globe so as in some places to carry the dry ground under the sea1 and in others to raise the sea-bed above the water4 ,let us suppose1 then1 that the great ,dismal ,swamp was gradually to sink down so that the sea washed over it and killed the reeds and shrubs4 ,then the streams from the west would not be sifted any longer but would bring down mud1 and leave it1 as in the delta of the ,nile or ,mississippi1 to make a layer over the dead plants4 ,you will easily understand that this mud would have many pieces of dead trees and plants in it1 which were stifled and died as it covered them over2 and thus the remains would be preserved like those which we find now in the roof of the coal-galleries4 ,but still there are the thick sandstones in the coal-mine to be explained4 ,how did they come there8 ,to explain them1 we must suppose that the ground went on sinking till the sea covered the whole place where once the swamp had been1 and then sea-sand would be thrown down over the clay and gradually pressed down by the weight of new sand above1 till it formed solid sandstone and our coal-bed became buried deeper and deeper in the earth4 ,at last1 after long ages1 when the thick mass of sandstones above the bed b 7,fig4 #df7 had been laid down1 the sinking must have stopped and the land have risen a little1 so that the sea was driven back2 and then the rivers would bring down earth again and make another clay-bed4 ,then a new forest would spring up1 the ferns1 ,calamites1 ,lepidodendrons1 and ,sigillarias would gradually form another jungle1 and many hundred of feet above the buried coal-bed b1 a second bed of peat and vegetable matter would begin to accumulate to form the coal-bed a4 ,such is the history of how the coal which we now dig out of the depths of the earth once grew as beautiful plants on the surface4 ,we cannot tell exactly all the ground over which these forests grew in ,england1 because some of the coal they made has been carried away since by rivers and cut down by the waves of the sea1 but we can say that wherever there is coal now1 there they must have been then4 ,try and picture to yourselves that on the east coast of ,northumberland and ,durham1 where all is now black with coal- dust1 and grimy with the smoke of furnaces2 and where the noise of hammers and steam-engines1 and of carts and trucks hurrying to and fro1 makes the country re-echo with the sound of labour2 there ages ago in the silent swamp shaded with monster trees1 one thin layer of plants after another was formed1 year after year1 to become the coal we now value so much4 ,in ,lancashire1 busy ,lancashire1 the same thing was happening1 and even in the middle of ,yorkshire and ,derbyshire the sea must have come up and washed a silent shore where a vast forest spread out over at least #gjj or #hjj square miles4 ,in ,stafford-shire1 too1 which is now almost the middle of ,england1 another small coal-field tells the same story1 while in ,south ,wales the deep coal-mines and number of coal-seams remind us how for centuries and centuries forests must have flourished and have disappeared over and over again under the sand of the sea4 ,but what is it that has changed these beds of dead plants into hard1 stony coal8 ,in the first place you must remember they have been pressed down under an enormous weight of rocks above them4 ,we can learn something about this even from our common lead pencils4 ,at one time the graphite or pure carbon1 of which the blacklead 7as we wrongly call it7 of our pencils is made1 was dug solid out of the earth4 but so much has now been used that they are obliged to collect the graphite dust1 and press it under a heavy weight1 and this makes such solid pieces that they can cut them into leads for ordinary cedar pencils4 ,now the pressure which we can exert by machinery is absolutely nothing compared to the weight of all those hundreds of feet of solid rock which lie over the coal-beds1 and which has pressed them down for thousands and perhaps millions of years2 and besides this1 we know that parts of the inside of the earth are very hot1 and many of the rocks in which coal is found are altered by heat4 ,so we can picture to ourselves that the coal was not only squeezed into a solid mass1 but often much of the oil and gas which were in the leaves of the plants was driven out by heat1 and the whole baked1 as it were1 into one substance4 ,the difference between coal which flames and coal which burns only with a red heat1 is chiefly that one has been baked and crushed more than the other4 ,coal which flames has still got in it the tar and the gas and the oils which the plant stored up in its leaves1 and these when they escape again give back the sunbeams in a bright flame4 ,the hard stone coal1 on the contrary1 has lost a great part of these oils1 and only carbon remains1 which seizes hold of the oxygen of the air and burns without flame4 ,coke is pure carbon1 which we make artificially by driving out the oils and gases from coal1 and the gas we burn is part of what is driven out4 ,we can easily make coal-gas here in this room4 ,i have brought a tobacco-pipe1 the bowl of which is filled with a little powdered coal1 and the broad end cemented up with ,stourbridge clay4 ,when we place this bowl over a spirit-lamp and make it very hot1 the gas is driven out at the narrow end of the pipe and lights easily 7see ,fig4 #ec74 ,this is the way all our gas is made1 only that furnaces are used to bake the coal in1 and the gas is passed into large reservoirs till it is wanted for use4 ,you will find it difficult at first to understand how coal can be so full of oil and tar and gases1 until you have tried to think over how much of all these there is in plants1 and especially in seeds - think of the oils of almonds1 of lavender1 of cloves1 and of caraways2 and the oils of turpentine which we get from the pines1 and out of which tar is made4 ,when you remember these and many more1 and also how the seeds of the club-moss now are largely charged with oil1 you will easily imagine that the large masses of coal-plants which have been pressed together and broken and crushed1 would give out a great deal of oil which1 when made very hot1 rises up as gas4 ,you may often yourself see tar oozing out of the lumps of coal in a fire1 and making little black bubbles which burst and burn4 ,it is from this tar that ,james ,young first made the paraffin oil we burn in our lamps1 and the spirit benzoline comes from the same source4 ,from benzoline1 again1 we get a liquid called aniline1 from which are made so many of our beautiful dyes - mauve1 magenta1 and violet2 and what is still more curious1 the bitter almonds1 pear- drops1 and many other sweets which children like to well1 are actually flavoured by essences which come out of coal-tar4 ,thus from coal we get not only nearly all our heat and our light1 but beautiful colours and pleasant flavours4 ,we spoke just now of the plants of the coal as being without beautiful flowers1 and yet we see that long1 long after their death they give us lovely colours and tints as beautiful as any in flower-world now4 ,think1 then1 how much we owe to these plants which lived and died so long ago6 ,if they had been able to reason1 perhaps they might have said that they did not seem of much use in the world4 ,they had no pretty flowers1 and there was no one to admire their beautiful green foliage except a few croaking reptiles1 and little crickets and grasshoppers2 and they lived and died all on one spot1 generation after generation1 without seeming to do much good to anything or anybody4 ,then they were covered up and put out of sight1 and down in the dark earth they were pressed all out of shape and lost their beauty and became only black1 hard coal4 ,there they lay for centuries and centuries1 and thousands and thousands of years1 and still no one seemed to want them4 ,at last1 one day1 long1 long after man had been living on the earth1 and had been burning wood for fires1 and so gradually using up the trees in the forests1 it was discovered that this black stone would burn1 and from that time coal has been becoming every day more and more useful4 ,without it not only should we have been without warmth in our houses1 or light in our streets when the stock of forest-wood was used up2 but we could never have melted large quantities of iron-stone and extracted the iron4 ,we have proof of this in ,sussex4 ,the whole country is full of iron-stone1 and the railings of ,st4 ,paul's churchyard are made of ,sussex iron4 ,iron-foundries were at work there as long as there was wood enough to supply them1 but gradually the works fell into disuse1 and the last furnace was put out in the year #ahji4 ,so now1 because there is no coal in ,sussex1 the iron lies idle1 while in the ,north1 where the iron-stone is near the coal- mines1 hundreds of tons are melted out every day4 ,again1 without coal we could have had no engines of any kind1 and consequently no large manufactories of cotton goods1 linen goods1 or cutlery4 ,in fact1 almost everything we use could only have been made with difficulty and in small quantities2 and even if we could have made them it would have been impossible to have sent them so quickly all over the world without coal1 for we could have had no railways or steamships1 but must have carried all goods along canals1 and by slow sailing vessels4 ,we ourselves must have taken days to perform journeys now made in a few hours1 and months to reach our colonies4 ,in consequence of this we should have remained a very poor people4 ,without manufactories and industries we should have had to live chiefly by tilling the ground1 and everyone being obliged to toil for daily bread1 there would have been much less time or opportunity for anyone to study science1 or literature1 or history1 or to provide themselves with comforts and refinements of life4 ,all this then1 those plants and trees of the far-off ages1 which seemed to lead such useless lives1 have done and are doing for us4 ,there are many people in the world who complain that life is dull1 that they do not see the use of it1 and that there seems no work specially for them to do4 ,i would advise such people1 whether they are grown up or little children1 to read the story of the plants which form the coal4 ,these saw no results during their own short existences1 they only lived and enjoyed the bright sunshine1 and did their work1 and were content4 ,and now thousands1 probably millions1 of years after they lived and died1 ,england owes her greatness1 and we much of our happiness and comfort1 to the sunbeams which those plants wove into their lives4 ,they burst forth again in our fires1 in our brilliant lights1 and in our engines1 and do the greater part of our work2 teaching us ,that nothing walks with aimless feet ,that not one life shall be destroyed1 ,or cast as rubbish to the void1 ,when ,god hath made the pile complete4 ,in ,memoriam ,week #be ,lecture ,,ix ,bees in the ,hive ,i am going to ask you to visit with me to-day one of the most wonderful cities with no human beings in it1 and yet it is densely populated1 for such a city may contain from twenty thousand to sixty thousand inhabitants4 ,in it you will find streets1 but no pavements1 for the inhabitants walk along the walls of the houses2 while in the houses you will see no windows1 for each house just fits its owner1 and the door is the only opening in it4 ,though made without hands these houses are most evenly and regularly built in tiers one above the other2 and here and there a few royal palaces1 larger and more spacious than the rest1 catch the eye conspicuously as they stand out at the corners of the streets4 ,some of the ordinary houses are used to live in1 while others serve as storehouses where food is laid up in the summer to feed the inhabitants during the winter1 when they are not allowed to go outside the walls4 ,not that the gates are ever shut3 that is not necessary1 for in this wonderful city each citizen follows the laws2 going out when it is time to go out1 coming home at proper hours1 and staying at home when it is his or her duty4 ,and in the winter1 when it is very cold outside1 the inhabitants1 having no fires1 keep themselves warm within the city by clustering together1 and never venturing out of doors4 ,one single queen reigns over the whole of this numerous population1 and you might perhaps fancy that1 having so many subjects to work for her and wait upon her1 she would do nothing but amuse herself4 ,on the contrary1 she too obeys the laws laid down for her guidance1 and never1 except on one or two state occasions1 goes out of the city1 but works as hard as the rest in performing her own royal duties4 ,from sunrise to sunset1 whenever the weather is fine1 all is life1 activity1 and bustle in this busy city4 ,though the gates are so narrow that two inhabitants can only just pass each other on their way through them1 yet thousands go in and out every hour of the day2 some bringing in materials to build new houses1 others food and provisions to store up for the winter2 and while all appears confusion and disorder among this rapidly moving throng1 yet in reality each has her own work to do1 and perfect order reigns over the whole4 ,even if you did not already know from the title of the lecture what city this is that ,i am describing1 you would no doubt guess that it is a beehive4 ,for where in the whole world1 except indeed upon an anthill1 can we find so busy1 so industrious1 or so orderly a community as among the bees8 ,more than a hundred years ago1 a blind naturalist1 ,francois ,huber1 set himself to study the habits of these wonderful insects and with the help of his wife and an intelligent manservant managed to learn most of their secrets4 ,before his time all naturalists had failed in watching bees1 because if they put them in hives with glass windows1 the bees1 not liking the light1 closed up the windows with cement before they began to work4 ,but ,huber invented a hive which he could open and close at will1 putting a glass hive inside it1 and by this means he was able to surprise the bees at their work4 ,thanks to his studies1 and to those of other naturalists who have followed in his steps1 we now know almost as much about the home of bees as we do about our own2 and if we follow out to-day the building of a bee-city and the life of its inhabitants1 ,i think you will acknowledge that they are a wonderful community1 and that it is a great compliment to anyone to say that he or she is as busy as a bee4 ,in order to begin at the beginning of the story1 let us suppose that we go into a country garden one fine morning in ,may when the sun is shining brightly overhead1 and that we see hanging from the bough of an old apple-tree a black object which looks very much like a large plum-pudding4 ,on approaching it1 however1 we see that it is a large cluster or swarm of bees clinging to each other by their legs2 each bee with its two fore-legs clinging to the two hinder legs of the one above it4 ,in this way as many as #bj1jjj bees may be clinging together1 and yet they hang so freely that a bee1 even from quite the centre of the swarm1 can disengage herself from her neighbours and pass through to the outside of the cluster whenever she wishes4 ,if these bees were left to themselves1 they would find a home after a time in a hollow tree1 or under the roof of a house1 or in some other cavity1 and begin to build their honeycomb there4 ,but as we do not wish to lose their honey we will bring a hive1 and1 holding it under the swarm1 shake the bough gently so that the bees fall into it1 and cling to the sides as we turn it over on a piece of clean linen1 on the stand where the hive is to be4 ,and now let us suppose that we are able to watch what is going on in the hive4 ,before five minutes are over the industrious little insects have begun to disperse and to make arrangements in their new home4 ,a number 7perhaps about two thousand7 of large1 lumbering bees of a darker colour than the rest1 will it is true1 wander aimlessly about the hive1 and wait for the others to feed them and house them2 but these are the drones1 or male bees 7#c1 ,fig4 #ed71 who never do any work except during one or two days in their whole lives4 ,but the smaller working bees 7#a1 ,fig4 #ed7 begin to be busy at once4 ,some fly off in search of honey4 ,others walk carefully all round the inside of the hive to see if there are any cracks in it2 and if there are1 they go off to the horse-chestnut trees1 poplars1 hollyhocks1 or other plants which have sticky buds1 and gather a kind of gum called propolis1 with which they cement the cracks and make them air-tight4 ,others again1 cluster round one bee 7#b1 ,fig4 #ed7 blacker than the rest and having a longer body and shorter wings2 for this is the queen-bee1 the mother of the hive1 and she must be watched and tended4 ,but the largest number begin to hang in a cluster from the roof just as they did from the bough of the apple tree4 ,what are they doing there8 ,watch for a little while and you will soon see one bee come out from among its companions and settle on the top of the inside of the hive1 turning herself round and round1 so as to push the other bees back1 and to make a space in which she can work4 ,then she will begin to pick at the under part of her body with her fore-legs1 and will bring a scale of wax from a curious sort of pocket under her abdomen4 ,holding this wax in her claws1 she will bite it with her hard1 pointed upper jaws1 which move to and fro sideways like a pair of pincers1 then1 moistening it with her tongue into a kind of paste1 she will draw it out like a ribbon and plaster it on the top of the hive4 ,after that she will take another piece2 for she has eight of these little wax-pockets1 and she will go on till they are all exhausted4 ,then she will fly away out of the hive1 leaving a small lump on the hive ceiling or on the bar stretched across it2 then her place will be taken by another bee who will go through the same manoeuvres4 ,this bee will be followed by another1 and another1 till a large wall of wax has been built1 hanging from the bar of the hive as in ,fig4 #ee1 only that it will not yet have cells fashioned in it4 ,meanwhile the bees which have been gathering honey out of doors begin to come back laden4 ,but they cannot store their honey1 for there are no cells made yet to put it in2 neither can they build combs with the rest1 for they have no wax in their wax-pockets4 ,so they just go and hang quietly on to the other bees1 and there they remain for twenty-four hours1 during which time they digest the honey they have gathered1 and part of it forms wax and oozes out from the scales under their body4 ,then they are prepared to join the others at work and plaster wax on to the hive4 ,week #bf ,and now1 as soon as a rough lump of wax is ready1 another set of bees come to do their work4 ,these are called the nursing bees1 because they prepare the cells and feed the young ones4 ,one of these bees1 standing on the roof of the hive1 begins to force her head into the wax1 biting with her jaws and moving her head to and fro4 ,soon she has made the beginning of a round hollow1 and then she passes on to make another1 while a second bee takes her place and enlarges the first one4 ,as many as twenty bees will be employed in this way1 one after another1 upon each hole before it is large enough for the base of a cell4 ,meanwhile another set of nursing bees have been working just in the same way on the other side of the wax1 and so a series of hollows are made back to back all over the comb4 ,then the bees form the walls of the cells and soon a number of six-sided tubes1 about half an inch deep1 stand all along each side of the comb ready to receive honey or bee-eggs4 ,you can see the shape of these cells in c1d1 ,fig4 #ef1 and notice how closely they fit into each other4 ,even the ends are so shaped that1 as they lie back to back1 the bottom of one cell 7,b1 ,fig4 #ef7 fits into the space between the ends of three cells meeting it from the opposite side 7,a1 ,fig4 #ef71 while they fit into the spaces around it4 ,upon this plan the clever little bees fill every atom of space1 use the least possible quantity of wax1 and make the cells lie so closely together that the whole comb is kept warm when the young bees are in it4 ,there are some kinds of bees who do not live in hives1 but each one builds a home of its own4 ,these bees - such as the upholsterer bee1 which digs a hole in the earth and lines it with flowers and leaves1 and the mason bee1 which builds in walls - do not make six-sided cells1 but round ones1 for room is no object to them4 ,but nature has gradually taught the little hive-bee to build its cells more and more closely1 till they fit perfectly within each other4 ,if you make a number of round holes close together in a soft substance1 and then squeeze the substance evenly from all sides1 the rounds will gradually take a six-sided form1 showing that this is the closest shape into which they can be compressed4 ,although the bee does not know this1 yet as gnaws away every bit of wax that can be spared she brings the holes into this shape4 ,as soon as one comb is finished1 the bees begin another by the side of it1 leaving a narrow lane between1 just broad enough for two bees to pass back to back as they crawl along1 and so the work goes on till the hive is full of combs4 ,as soon1 however1 as a length of about five or six inches of the first comb has been made into cells1 the bees which are bringing home honey no longer hang to make it into wax1 but begin to store it in the cells4 ,we all know where the bees go to fetch their honey1 and how1 when a bee settles on a flower1 she thrusts into it her small tongue-like proboscis1 which is really a lengthened under-lip1 and sucks out the drop of honey4 ,this she swallows1 passing it down her throat into a honey-bag or first stomach1 which lies between her throat and her real stomach1 and when she gets back to the hive she can empty this bag and pass honey back through her mouth again into the honey-cells4 ,but if you watch bees carefully1 especially in the spring-time1 you will find that they carry off something else besides honey4 ,early in the morning1 when the dew is on the ground1 or later in the day1 in moist shady places1 you may see a bee rubbing itself against a flower1 or biting those bags of yellow dust or pollen which we mentioned in ,lecture ,,vii4 ,when she has covered herself with pollen1 she will brush it off with her feet1 and1 bringing it to her mouth1 she will moisten and roll it into a little ball1 and then pass it back from the first pair of legs to the second and so to the third or hinder pair4 ,here she will pack it into a little hairy groove called a basket in the joint of one of the hind legs1 where you may see it1 looking like a swelled joint1 as she hovers among the flowers4 ,she often fills both hind legs in this way1 and when she arrives back at the hive the nursing bees take the lumps form her1 and eat it themselves1 or mix it with honey to feed the young bees2 or1 when they have any to spare1 store it away in old honey-cells to be used by-and-by4 ,this is the dark1 bitter stuff called bee- bread which you often find in a honeycomb1 especially in a comb which has been filled late in the summer4 ,when the bee has been relieved of the bee-bread she goes off to one of the clean cells in the new comb1 and1 standing on the edge1 throws up the honey from the honey-bag into the cell4 ,one cell will hold the contents of many honey-bags1 and so the busy little workers have to work all day filling cell after cell1 in which the honey lies uncovered1 being too thick and sticky to flow out1 and is used for daily food - unless there is any to spare1 and then they close up the cells with wax to keep for the winter4 ,meanwhile1 a day or two after the bees have settled in the hive1 the queen-bee begins to get very restless4 ,she goes outside the hive and hovers about a little while1 and then comes in again1 and though generally the bees all look very closely after her to keep her indoors1 yet now they let her do as she likes4 ,again she goes out1 and again back1 and then1 at last1 she soars up into the air and flies away4 ,but she is not allowed to go alone4 ,all the drones of the hive rise up after her1 forming a guard of honour to follow her wherever she goes4 ,in about half-an-hour she comes back again1 and then the working bees all gather round her1 knowing that now she will remain quietly in the hive and spend all her time in laying eggs2 for it is the queen-bee who lays all the eggs in the hive4 ,this she begins to do about two days after her flight4 ,there are now many cells ready besides those filled with honey2 and1 escorted by several bees1 the queen-bee goes to one of these1 and1 putting her head into it remains there a second as if she were examining whether it would make a good home for the young bee4 ,then1 coming out1 she turns round and lays a small1 oval1 bluish-white egg in the cell4 ,after this she takes no more notice of it1 but goes on to the next cell and the next1 doing the same thing1 and laying eggs in all the empty cells equally on both sides of the comb4 ,she goes on so quickly that she sometimes lays as many as #bjj eggs in one day4 ,then the work of the nursing bees begins4 ,in two or three days each egg has become a tiny maggot or larva1 and the nursing bees put into its cell a mixture of pollen and honey which they have prepared in their own mouths1 thus making a kind of sweet bath in which the larva lies4 ,in five or six days the larva grows so fat upon this that it nearly fills the cell1 and then the bees seal up the mouth of the cell with a thin cover of wax1 made of little rings and with a tiny hole in the centre4 ,as soon as the larva is covered in1 it begins to give out from its under-lip a whitish1 silken film1 made of two threads of silk glued together1 and with this it spins a covering or cocoon all round itself1 and so it remains for about ten days more4 ,at last1 just twenty-one days after the egg was laid1 the young bee is quite perfect1 lying in the cell as in ,fig4 #eg1 and she begins to eat her way through the cocoon and through the waxen lid1 and scrambles out of her cell4 ,then the nurses come again to her1 stroke her wings and feed her for twenty-four hours1 and after that she is quite ready to begin work1 and flies out to gather honey and pollen like the rest of the workers4 ,by this time the number of working bees in the hive is becoming very great1 and the storing of honey and pollen-dust goes on very quickly4 ,even the empty cells which the young bees have left are cleaned out by the nurses and filled with honey2 and this honey is darker than that stored in clean cells1 and which we always call virgin honey because it is so pure and clear4 ,at last1 after six weeks1 the queen leaves off laying worker- eggs1 and begins to lay1 in some rather larger cells1 eggs from which drones1 or male bees1 will grow up in about twenty days4 ,meanwhile the worker-bees have been building on the edge of the cones some very curious cells 7q1 ,fig4 #eg7 which look like thimbles hanging with the open side upwards1 and about every three days the queen stops in laying drone-eggs and goes to put an egg in one of these cells4 ,notice that she waits three days between each of these peculiar layings1 because we shall see presently that there is a good reason for her doing so4 ,the nursing bees take great care of these eggs1 and instead of putting ordinary food into the cell1 they fill it with a sweet1 pungent jelly1 for this larva is to become a princess and a future queen bee4 ,curiously enough1 it seems to be the peculiar food and the size of the cell which makes the larva grow into a mother-bee which can lay eggs1 for if a hive has the misfortune to lose its queen1 they take one of the ordinary worker-larvae and put it into a royal cell and feed it with jelly1 and it becomes a queen-bee4 ,as soon as the princess is shut in like the others1 she begins to spin her cocoon1 but she does not quite close it as the other bees do1 but leaves a hole at the top4 ,week #bg ,at the end of sixteen days after the first royal egg was laid1 the eldest princess begins to try to eat her way out of her cell1 and about this time the old queen becomes very uneasy1 and wanders about distractedly4 ,the reason of this is that there can never be two queen-bees in one hive1 and the queen knows that her daughter will soon be coming out of her cradle and will try to turn her off her throne4 ,so1 not wishing to have to fight for her kingdom1 she makes up her mind to seek a new home and take a number of her subjects with her4 ,if you watch the hive about this time you will notice many of the bees clustering together after they have brought in their honey1 and hanging patiently1 in order to have plenty of wax ready to use when they start1 while the queen keeps a sharp look-out for a bright1 sunny day1 on which they can swarm3 for bees will never swarm on a wet or doubtful day if they can possibly help it1 and we can easily understand why1 when we consider how the rain would clog their wings and spoil the wax under their bodies4 ,meanwhile the young princess grows very impatient1 and tries to get out of her cell1 but the worker-bees drive her back1 for they know there would be a terrible fight if the two queens met4 ,so they close up the hole she has made with fresh wax after having put in some food for her to live upon till she is released4 ,at last a suitable day arrives1 and about ten or eleven o'clock in the morning the old queen leaves the hive1 taking with her about #bjjj drones and from #ab1jjj to #bj1jjj worker-bees1 which fly a little way clustering round her till she alights on the bough of some tree1 and then they form a compact swarm ready for a new hive or to find a home of their own4 ,leaving them to go their way1 we will now return to the old hive4 ,here the liberated princess is reigning in all her glory2 the worker-bees crowd round her1 watch over her1 and feed her as though they could not do enough to show her honour4 ,but still she is not happy4 ,she is restless1 and runs about as if looking for an enemy1 and she tries to get at the remaining royal cells where the other young princesses are still shut in4 ,but the workers will not let her touch them1 and at last she stands still and begins to beat the air with her wings and to tremble all over1 moving more and more quickly1 till she makes quite a loud1 piping noise4 ,hark6 ,what is that note answering her8 ,it is a low1 hoarse sound1 and it comes from the cell of the next eldest princess4 ,now we see why the young queen has been so restless4 ,she knows her sister will soon come out1 and the louder and stronger the sound becomes within the cell1 the sooner she knows the fight will have to begin4 ,and so she makes up her mind to follow her mother's example and to lead off a second swarm4 ,but she cannot always stop to choose a fine day1 for her sister is growing very strong and may come out of her cell before she is off4 ,and so the second1 or after swarm1 gets ready and goes away4 ,and this explains why princesses' eggs are laid a few days apart1 for if they were laid all on the same day1 there would be no time for one princess to go off with a swarm before the other came out of her cell4 ,sometimes1 when the workers are not watchful enough1 two queens do meet1 and then they fight till one is killed2 or sometimes they both go off with the same swarm without finding each other out4 ,but this only delays the fight till they get into the new hive2 sooner or later one must be killed4 ,and now a third queen begins to reign in the old hive1 and she is just as restless as the preceding ones1 for there are still more princesses to be born4 ,but this time1 if no new swarm wants to start1 the workers do not try to protect the royal cells4 ,the young queen darts at the first she sees1 gnaws a hole with her jaws1 and1 thrusting in her sting through the hole in the cocoon1 kills the young bee while it is still a prisoner4 ,she then goes to the next1 and the next1 and never rests till all the young princesses are destroyed4 ,then she is contented1 for she knows no other queen will come to dethrone her4 ,after a few days she takes her flight in the air with the drones1 and comes home to settle down in the hive for the winter4 ,then a very curious scene takes place4 ,the drones are no more use1 for the queen will not fly out again1 and these idle bees will never do any work in the hive4 ,so the worker-bees begin to kill them1 falling upon them1 and stinging them to death1 and as the drones have no stings they cannot defend themselves1 and in a few days there is not a drone1 nor even a drone-egg1 left in the hive4 ,this massacre seems very sad to us1 since the poor drones have never done any harm beyond being hopelessly idle4 ,but it is less sad when we know that they could not live many weeks1 even if they were not attacked1 and1 with winter coming1 the bees cannot afford to feed useless mouths1 so a quick death is probably happier for them than starvation4 ,and now all the remaining inhabitants of the hive settle down to feeding the young bees and laying in the winter's store4 ,it is at this time1 after they have been toiling and saving1 that we come and take their honey2 and from a well-stocked hive we may even take #cj lbs4 without starving the industrious little inhabitants4 ,but then we must often feed them in return and give them sweet syrup in the late autumn and the next early spring when they cannot find any flowers4 ,although the hive has now become comparatively quiet and the work goes on without excitement1 yet every single bee is employed in some way1 either out of doors or about the hive4 ,besides the honey collectors and the nurses1 a certain number of bees are told off to ventilate the hive4 ,you will easily understand that where so many insects are packed closely together the heat will become very great1 and the air impure and unwholesome4 ,and the bees have no windows that they can open to let in fresh air1 so they are obliged to fan it in from the one opening of the hive4 ,the way in which they do this is very interesting4 ,some of the bees stand close to the entrance1 with their faces towards it1 and opening their wings1 so as to make them into fans1 they wave them to and fro1 producing a current of air4 ,behind these bees1 and all over the floor of the hive1 there stand others1 this time with their backs towards the entrance1 and fan in the same manner1 and in this way air is sent into all the passages4 ,another set of bees clean out the cells after the young bees are born1 and make them fit to receive honey1 while others guard the entrance of the hive to keep away the destructive wax-moth1 which tries to lay its eggs in the comb so that its young ones may feed on the honey4 ,all industrious people have to guard their property against thieves and vagabonds1 and the bees have many intruders1 such as wasps and snails and slugs1 which creep in whenever they get a chance4 ,if they succeed in escaping the sentinel bees1 then a fight takes place within the hive1 and the invader is stung to death4 ,sometimes1 however1 after they have killed the enemy1 the bees cannot get rid of his body1 for a snail or slug is too heavy to be easily moved1 and yet it would make the hive very unhealthy to allow it to remain4 ,in this dilemma the ingenious little bees fetch the gummy propolis from the plant-buds and cement the intruder all over1 thus embalming his body and preventing it from decaying4 ,and so the life of this wonderful city goes on4 ,building1 harvesting1 storing1 nursing1 ventilating and cleaning from morn till night1 the little worker-bee lives for about eight months1 and in that time has done quite her share of work in the world4 ,only the young bees1 born late in the season1 live on till the next year to work in the spring4 ,the queen-bee lives longer1 probably about two years1 and then she too dies1 after having had a family of many thousands of children4 ,we have already pointed out that in our fairy-land of nature all things work together so as to bring order out of apparent confusion4 ,but though we should naturally expect winds and currents1 rivers and clouds1 and even plants to follow fixed laws1 we should scarcely have looked for such regularity in the life of the active1 independent busy bee4 ,yet we see that she1 too1 has her own appointed work to do1 and does it regularly and in an orderly manner4 ,in this lecture we have been speaking entirely of the bee within the hive1 and noticing how marvellously her instincts guide her in her daily life4 ,but within the last few years we have learnt that she performs a most curious and wonderful work in the world outside her home and that we owe to her not only the sweet honey to eat1 but even in a great degree the beauty and gay colours of the flowers which she visits when collecting it4 ,this work will form the subject of our next lecture1 and while we love the little bee for her constant industry1 patience1 and order within the hive1 we shall1 ,i think1 marvel at the wonderful law of nature which guides her in her unconscious mission of love among the flowers which grow around it4 ,week #bh ,lecture ,x ,,bees ,,and ,,flowers ,whatever thoughts each one of you may have brought to the lecture to-day1 ,i want you to throw them all aside and fancy yourself to be in a pretty country garden on a hot summer's morning4 ,perhaps you have been walking1 or reading1 or playing1 but it is getting too hot now to do anything2 and so you have chosen the shadiest nook under the old walnut-tree1 close to the flower-bed on the lawn1 and would almost like to go to sleep if it were not too early in the day4 ,as you lie there thinking of nothing in particular1 except how pleasant it is to be idle now and then1 you notice a gentle buzzing close to you1 and you see that on the flower-bed close by1 several bees are working busily among the flowers4 ,they do not seem to mind the heat1 nor to wish to rest2 and they fly so lightly and look so happy over their work that it does not tire you to look at them4 ,that great humble-bee takes it leisurely enough as she goes lumbering along1 poking her head into the larkspurs1 and remaining so long in each you might almost think she had fallen asleep4 ,the brown hive-bee on the other hand1 moves busily and quickly among the stocks1 sweet peas1 and mignonette4 ,she is evidently out on active duty1 and means to get all she can from each flower1 so as to carry a good load back to the hive4 ,in some blossoms she does not stay a moment1 but draws her head back directly she has popped it in1 as if to say ,no honey there4 ,but over the full blossoms she lingers a little1 and then scrambles out again with her drop of honey1 and goes off to seek more in the next flower4 ,let us watch her a little more closely4 ,there are plenty of different plants growing in the flower-bed1 but1 curiously enough1 she does not go first to one kind and then to another2 but keeps to one1 perhaps the mignonette1 the whole time till she flies away4 ,rouse yourself up to follow her1 and you will see she takes her way back to the hive4 ,she may perhaps stop to visit a stray plant of mignonette on her way1 but no other flower will tempt her till she has taken her load home4 ,then when she comes back again she may perhaps go to another kind of flower1 such as the sweet peas1 for instance1 and keep to them during the next journey1 but it is more likely that she will be true to her old friend the mignonette for the whole day4 ,we all know why she makes so many journeys between the garden and the hive1 and that she is collecting drops of honey from each flower1 and carrying it to be stored up in the honeycomb for winter's food4 ,how she stores it1 and how she also gathers pollen-dust for her bee-bread1 we saw in the last lecture2 to-day we will follow her in her work among the flowers1 and see1 while they are so useful to her1 what she is doing for them in return4 ,we have already learnt from the life of a primrose that plants can make better and stronger seeds when they can get pollen-dust from another plant1 than when they are obliged to use that which grows in the same flower2 but ,i am sure you will be very much surprised to hear that the more we study flowers the more we find that their colours1 their scent1 and their curious shapes are all so many baits and traps set by nature to entice insects to come to the flowers1 and carry this pollen-dust from one to the other4 ,so far as we know1 it is entirely for this purpose that the plants form honey in different parts of the flower1 sometimes in little bags or glands1 as in the petals of the buttercup flower1 sometimes in clear drops1 as in the tube of the honeysuckle4 ,this food they prepare for the insects1 and then they have all sorts of contrivances to entice them to come and fetch it4 ,you will remember that the plants of the coal had no bright or conspicuous flowers4 ,now we can understand why this was1 for there were no flying insects at that time to carry the pollen- dust from flower to flower1 and therefore there was no need of coloured flowers to attract them4 ,but little by little1 as flies1 butterflies1 moths and bees began to live in the world1 flowers too began to appear1 and plants hung out these gay- coloured signs1 as much as to say1 ,come to me1 and ,i will give you honey if you will bring me pollen-dust in exchange1 so that my seeds may grow healthy and strong4 ,we cannot stop to inquire to-day how this all gradually came about1 and how the flowers gradually put on gay colours and curious shapes to tempt the insects to visit them2 but we will learn something about the way they attract them now1 and how you may see it for yourselves if you keep your eyes open4 ,for example1 if you watch the different kinds of grasses1 sedges and rushes1 which have such tiny flowers that you can scarcely see them1 you will find that no insects visit them4 ,neither will you ever find bees buzzing round oak-trees1 nut-trees1 willows1 elms or birches4 ,but on the pretty and sweet-smelling apple- blossoms1 or the strongly scented lime-trees1 you will find bees1 wasps1 and plenty of other insects4 ,the reason of this is that grasses1 sedges1 rushes1 nut-trees1 willow1 and the others we have mentioned1 have all of them a great deal of pollen-dust1 and as the wind blows them to and fro1 it wafts the dust from one flower to another1 and so these plants do not want the insects1 and it is not worth their while to give out honey1 or to have gaudy or sweet-scented flowers to attract them4 ,but wherever you see bright or conspicuous flowers you may be quite sure that the plants want the bees or some other winged insect to come and carry their pollen for them4 ,snowdrops hanging their white heads among their green leaves1 crocuses with their violet and yellow flowers1 the gaudy poppy1 the large- flowered hollyhock or the sunflower1 the flaunting dandelion1 the pretty pink willow-herb1 the clustered blossoms of the mustard and turnip flowers1 the bright blue forget-me-not and the delicate little yellow trefoil1 all these are visited by insects1 which easily catch sight of them as they pass by and hasten to sip their honey4 ,sir ,john ,lubbock has shown that bees are not only attracted by bright colours1 but that they even know one colour from another4 ,he put some honey on slips of glass with coloured papers under them1 and when he had accustomed the bees to find the honey always on the blue glass1 he washed this glass clean1 and put the honey on the red glass instead4 ,now if the bees had followed only the smell of the honey1 they would have flown to the red glass1 but they did not4 ,they went first to the blue glass1 expecting to find the honey on the usual colour1 and it was only when they were disappointed that they went off to the red4 ,is it not beautiful to think that the bright pleasant colours we love so much in flowers1 are not only ornamental1 but that they are useful and doing their part in keeping up healthy life in our world8 ,neither must we forget what sweet scents can do4 ,have you never noticed the delicious smell which comes from beds of mignonette1 thyme1 rosemary1 mint1 or sweet alyssum1 from the small hidden bunches of laurustinus blossom1 or from the tiny flowers of the privet8 ,these plants have found another way of attracting the insects2 they have no need of bright colours1 for their scent is quite as true and certain a guide4 ,you will be surprised if you once begin to count them up1 how many white and dull or dark- looking flowers are sweet-scented1 while gaudy flowers1 such as tulip1 foxglove and hollyhock1 have little or no scent4 ,and then1 just as in the world we find some people who have everything to attract others to them1 beauty and gentleness1 cleverness1 kindliness1 and loving sympathy1 so we find some flowers1 like the beautiful lily1 the lovely rose1 and the delicate hyacinth1 which have colour and scent and graceful shapes all combined4 ,but we are not yet nearly at an end of the contrivances of flowers to secure the visits of insects4 ,have you not observed that different flowers open and close at different times8 ,the daisy receives its name day's eye1 because it opens at sunrise and closes at sunset1 while the evening primrose 7,aenothera biennis7 and the night campion 7,silene noctiflora7 spread out their flowers just as the daisy is going to bed4 ,what do you think is the reason of this8 ,if you go near a bed of evening primroses just when the sun is setting1 you will soon be able to guess1 for they will then give out such a sweet scent that you will not doubt for a moment that they are calling the evening moths to come and visit them4 ,the daisy opens by day1 because it is visited by day insects1 but those particular moths which can carry the pollen-dust of the evening primrose1 fly only by night1 and if this flower opened by day other insects might steal its honey1 while they would not be the right size or shape to touch its pollen-bags and carry the dust4 ,it is the same if you pass by a honeysuckle in the evening2 you will be surprised how much stronger its scent is than in the day- time4 ,this is because the sphinx hawk-moth is the favourite visitor of that flower1 and comes at nightfall1 guided by the strong scent1 to suck out the honey with its long proboscis1 and carry the pollen-dust4 ,again1 some flowers close whenever rain is coming4 ,the pimpernel 7,anagallis arvensis7 is one of these1 hence its name of the ,shepherd's ,weather-glass4 ,this little flower closes1 no doubt1 to prevent its pollen-dust being washed away1 for it has no honey2 while other flowers do it to protect the drop of honey at the bottom of their corolla4 ,look at the daisies for example when a storm is coming on2 as the sky grows dark and heavy1 you will see them shrink up and close till the sun shines again4 ,they do this because in each of the little yellow florets in the centre of the flower there is a drop of honey which would be quite spoiled if it were washed by the rain4 ,and now you will see why cup-shaped flowers so often droop their heads - think of the harebell1 the snowdrop1 the lily-of-the- valley1 the campanula1 and a host of others2 how pretty they look with their bells hanging so modestly from the slender stalk6 ,they are bending down to protect the honey-glands within them1 for if the cup became full of rain or dew the honey would be useless1 and the insects would cease to visit them4 ,week #bi ,but it is not only necessary that the flowers should keep their honey for the insects1 they also have to take care and keep it for the right kind of insect4 ,ants are in many cases great enemies to them1 for they like honey as much as bees and butterflies do1 yet you will easily see that they are so small that if they creep into a flower they pass the anthers without rubbing against them1 and so take the honey without doing any good to the plant4 ,therefore we find numberless contrivances for keeping the ants and other creeping insects away4 ,look for example at the hairy stalk of the primrose flower2 those little hairs are like a forest to a tiny ant1 and they protect the flower from his visits4 ,the ,spanish catchfly 7,silene otites71 on the other hand1 has a smooth1 but very gummy stem1 and on this the insects stick1 if they try to climb4 ,slugs and snails too will often attack and bite flowers1 unless they are kept away by thorns and bristles1 such as we find on the teazel and the burdock4 ,and so we are gradually learning that everything which a plant does has its meaning1 if we can only find it out1 and that even very insignificant hair has its own proper use1 and when we are once aware of this a flower-garden may become quite a new world to us if we open our eyes to all that is going on in it4 ,but as we cannot wander among many plants to-day1 let us take a few which the bees visit1 and see how they contrive not to give up their honey without getting help in return4 ,we will start with the blue wood-geranium1 because from it we first began to learn the use of insects to flowers4 ,more than a hundred years ago a young ,german botanist1 ,christian ,conrad ,sprengel1 noticed some soft hairs growing in the centre of this flower1 just round the stamens1 and he was so sure that every part of a plant is useful1 that he set himself to find out what these hairs meant4 ,he soon discovered that they protected some small honey-bags at the base of the stamens1 and kept the rain from washing the honey away1 just as our eyebrows prevent the perspiration on our faces from running into our eyes4 ,this led him to notice that plants take great care to keep their honey for insects1 and by degrees he proved that they did this in order to tempt the insects to visit them and carry off their pollen4 ,the first thing to notice in this little geranium flower is that the purple lines which ornament it all point directly to the place where the honey lies at the bottom of the stamens1 and actually serve to lead the bee to the honey2 and this is true of the veins and marking of nearly all flowers except of those which open by night1 and in these they would be useless1 for the insects would not see them4 ,when the geranium first opens1 all its ten stamens are lying flat on the corolla or coloured crown1 as in the left-hand flower in ,fig4 #eh1 and then the bee cannot get at the honey4 ,but in a short time five stamens begin to raise themselves and cling round the stigma or knob at the top of the seed-vessel1 as in the middle flower4 ,now you would think they would leave their dust there4 ,but no6 the stigma is closed up so tight that the dust cannot get on to the sticky part4 ,now1 however1 the bee can get at the honey-glands on the outside of the raised stamens2 and as he sucks it1 his back touches the anthers or dust-bags1 and he carries off the pollen4 ,then1 as soon as all their dust is gone1 these five stamens fall down1 and the other five spring up4 ,still1 however1 the stigma remains closed1 and the pollen of these stamens1 too1 may be carried away to another flower4 ,at last these five also fall down1 and then1 and not till then1 the stigma opens and lays out its five sticky points1 as you may see in the right-hand flower1 ,fig4 #eh4 ,but its own pollen is all gone1 how then will it get any8 ,it will get it from some bee who has just taken it from another and younger flower2 and thus you see the blossom is prevented from using its own pollen1 and made to use that of another blossom1 so that its seeds may grow healthy and strong4 ,the garden nasturtium1 into whose blossom we saw the humble-bee poling his head1 takes still more care of its pollen-dust4 ,it hides its honey down at the end of its long spur1 and only sends out one stamen at a time instead of five like the geranium2 and then1 when all the stamens have had their turn1 the sticky knob comes out last for pollen from another flower4 ,all this you may see for yourselves if you find geraniums99 in the hedges1 and nasturtiums in you garden4 ,but even if you have not these1 you may learn the history of another flower quite as curious1 and which you can find in any field or lane even near ,london4 ,the common dead-nettle 7,fig4 #ei7 takes a great deal of trouble in order that the bee may carry off its pollen4 ,when you have found one of these plants1 take a flower from the ring all round the stalk and tear it gently open1 so that you can see down its throat4 ,there1 just at the very bottom1 you will find a thick fringe of hairs1 and you will guess at once that these are to protect a drop of honey below4 ,little insects which would creep into the flower and rob it of its honey without touching the anthers of the stamens cannot get past these hairs1 and so the drop is kept till the bee comes to fetch it4 799,the scarlet and other bright geraniums of our flower-gardens are not true geraniums1 but pelargoniums4 ,you may1 however1 watch all these peculiarities in them if you cannot procure the true wild geranium47 ,now look for the stamens2 there are four of them1 two long and two short1 and they are quite hidden under the hood which forms the top of the flower4 ,how will the bee touch them8 ,if you were to watch one1 you would find that when the bee alights on the broad lip and thrusts her head down the tube1 she first of all knows her back against the little forked tip4 ,this is the sticky stigma1 and she leaves there any dust she has brought from another flower2 then1 as she must push far in to reach the honey1 before she comes out again has carried away the yellow powder on her back1 ready to give it to the next flower4 ,do you remember how we noticed at the beginning of the lecture that a bee always likes to visit the same kind of plant in one journey8 ,you see now that this is very useful to the flowers4 ,if the bee went from a dead-nettle to a geranium1 the dust would be lost1 for it would be of no use to any other plant but a dead- nettle4 ,but since the bee likes to get the same kind of honey each journey1 she goes to the same kind of flowers1 and places the pollen-dust just where it is wanted4 ,there is another flower1 called the ,salvia1 which belongs to the same family as our dead-nettle1 and ,i think you will agree with me that its way of dusting the bee's back is most clever4 ,the ,salvia 7,fig4 #fj7 is shaped just like the dead-nettle1 with a hood and a broad lip1 but instead of four stamens it has only two1 the other two being shrivelled up4 ,the two that are left have a very strange shape1 for the stalk or filament of the stamen is very short1 while the anther1 which is in most flowers two little bags stuck together1 has here grown out into a long thread1 with a little dust-bag at one end only4 ,in #a1 ,fig4 #fj1 you only see one of these stems1 because the flower is cut in half1 but in the whole flower1 one stands on each side just within the lip4 ,now1 when the bee puts her head into the tube to reach the honey1 she passes right between these two swinging anthers1 and knocking against the end pushes it before her and so brings the dust-bag plump down on her back1 scattering the dust there6 you can easily try this by thrusting a pencil into any ,salvia flower1 and you will see the anther fall4 ,you will notice that all this time the be does not touch the sticky stigma which hangs high above her1 but after the anthers are empty and shrivelled the stalk of the stigma grows longer1 and it falls lower down4 ,by-and-by another bee1 having pollen on her back1 comes to look for honey1 and as she goes into ,no4 #c1 she rubs against the stigma and leaves upon it the dust from another flower4 ,tell me1 has not the ,salvia1 while remaining so much the same shape as the dead-nettle1 devised a wonderful contrivance to make use of the visits of the bee8 ,the common sweet violet 7,viola odorata7 or the dog violet 7,viola canina71 which you can gather in any meadow1 give up their pollen-dust in quite a different way from the ,salvia1 and yet it is equally ingenious4 ,everyone has noticed what an irregular shape this flower has1 and that one of its purple petals has a curious spur sticking out behind4 ,in the tip of this spur and in the spur of the stamen lying in it the violet hides its honey1 and to reach it the bee must press past the curious ring of orange-tipped bodies in the middle of the flower4 ,these bodies are the anthers1 ,fig4 #fa1 which fit tightly round the stigma1 so that when the pollen-dust1 which is very dry1 comes out of the bags1 it remains shut in by the tips as if in a box4 ,two of these stamens have spurs which lie in the coloured spur of the flower1 and have honey at the end of them4 ,now1 when the bee shakes the end of the stigma1 it parts the ring of anthers1 and the fine dust falls through upon the insect4 ,let us see for a moment how wonderfully this flower is arranged to bring about the carrying of the pollen1 as ,sprengel pointed out years ago4 ,in the first place1 it hangs on a thin stalk1 and bends its head down so that the rain cannot come near the honey in the spur1 and also so that the pollen-dust falls forward into the front of the little box made by the closed anthers4 ,then the pollen is quite dry1 instead of being sticky as in most plants4 ,this is in order that it may fall easily through the cracks4 ,then the style or stalk of the stigma is very thin and its tip very broad1 so that it quivers easily when the bee touches it1 and so shakes the anthers apart1 while the anthers themselves fold over to make the box1 and yet not so tightly but that the dust can fall through when they are shaken4 ,lastly1 if you look at the veins of the flower1 you will find that they all point towards the spur where the honey is to be found1 so that when the sweet smell of the flower has brought the bee1 she cannot fail to go in at the right place4 ,two more flowers still ,i want us to examine together1 and then ,i hope you will care to look at every flower you meet1 to try and see what insects visit it1 and how its pollen-dust is carried4 ,these two flowers are the common ,bird's-foot trefoil 7,lotus corniculatus71 and the ,early ,orchis 7,orchis mascula71 which you may find in almost any moist meadow in the spring and early summer4 ,the ,bird's-foot trefoil1 ,fig4 #fb1 you will find almost anywhere all through the summer1 and you will know it from other flowers very like it by its leaf1 which is not a true trefoil1 for behind the three usual leaflets of the clover and the shamrock leaf1 it has two small leaflets near the stalk4 ,the flower1 you will notice1 is shaped very like the flower of a pea1 and indeed it belongs to the same family1 called the ,papilionaceae or butterfly family1 because the flowers look something like an insect flying4 ,in all these flowers the top petal stands up like a flag to catch the eye of the insect1 and for this reason botanists call it the standard4 ,below it are two side-petals called the wings1 and if you pick these off you will find that the remaining two petals are joined together at the tip in a shape like the keel of a boat4 ,for this reason they are called the keel4 ,notice as we pass that these two last petals have in them a curious little hollow or depression1 and if you look inside the wings you will notice a little knob that fits into this hollow1 and so locks the two together4 ,we shall see by-and-by that this is important4 ,week #cj ,next let us look at the half-flower when it is cut open1 and see what there is inside4 ,there are ten stamens in all1 enclosed with the stigma in the keel2 nine are joined together and one is by itself4 ,the anthers of five of these stamens burst open while the flower is still a bud1 but the other stamens go on growing1 and push the pollen-dust1 which is very moist and sticky1 right up into the tip of the keel4 ,here you see it lies right round the stigma1 but as we saw before in the geranium1 the stigma is not ripe and sticky yet1 and so it does not use the pollen grains4 ,now suppose that a bee comes to the flower4 ,the honey she has to fetch lies inside the tube1 and the one stamen being loose she is able to get her proboscis in4 but if she is to be of any use to the flower she must uncover the pollen-dust4 ,see how cunningly the flower has contrived this4 ,in order to put her head into the tube the bee must stand upon the wings1 and her weight bends them down4 but they are locked to the keel by the knob fitting in the hole1 and so the keel is pushed down too1 and the sticky pollen- dust is uncovered and comes right against the stomach of the bee and sticks there6 ,as soon as she has done feeding and flies away1 up go the wings and the keel with them1 covering up any pollen that remains ready for next time4 ,then when the bee goes to another flower1 as she touches the stigma as well as the pollen1 she leaves some of the foreign dust upon it1 and the flower uses that rather than its own1 because it is better for its seeds4 ,if however no bee happens to come to one of these flowers1 after a time the stigma becomes sticky and it uses its own pollen3 and this is perhaps one reason why the bird's-foot trefoil is so very common1 because it can do its own work if the bee does not help it4 ,now we come lastly to the ,orchis flower4 ,mr4 ,darwin has written a whole book on the many curious and wonderful ways in which orchids tempt bees and other insects to fertilize them4 ,we can only take the simplest1 but ,i think you will say that even this blossom is more like a conjuror's box than you would have supposed it possible that a flower could be4 ,let us examine it closely4 ,it has sic deep-red covering leaves1 ,fig4 #fb1 three belonging to the calyx or outer cup1 and three belonging to the corolla or crown of the flower2 but all six are coloured alike1 except that the large on in front1 called the lip1 has spots and lines upon it which will suggest to you at once that they point to the honey4 ,but where are the anthers1 and where is the stigma8 ,look just under the arch made by those three bending flower-leaves1 and there you will see two small slits1 and in these some little club-shaped bodies1 which you can pick out with the point of a needle4 ,one of these enlarged is shown4 ,it is composed of sticky grains of pollen held together by fine threads on the top of a thin stalk2 and at the bottom of the stalk there is a little round body4 ,this is all that you will find to represent the stamens of the flower4 ,when these masses of pollen1 or pollinia as they are called1 are within the flower1 the knob at the bottom is covered by a little lid1 shutting them in like the lid of a box1 and just below this lid you will see two yellowish lumps1 which are very sticky4 ,these are the top of the stigma1 and they are just above the seed-vessel1 which you can see in the lowest flower in the picture4 ,now let us see how this flower gives up its pollen4 ,when a bee comes to look for honey in the orchis1 she alights on the lip1 and guided by the lines makes straight for the opening just in front of the stigmas4 ,putting her head into this opening she pushes down into the spur1 where by biting the inside skin she gets some juicy sap4 ,notice that she has to bite1 which takes time4 ,you will see at once that she must touch the stigmas in going in1 and so give them any pollen she has on her head4 but she also touches the little lid and it flies instantly open1 bringing the glands at the end of the pollen-masses against her head4 ,these glands are moist and sticky1 and while she is gnawing the inside of the spur they dry a little and cling to her head and she brings them out with her4 ,darwin once caught a bee with as many as sixteen of these pollen-masses clinging to her head4 ,but if the bee went into the next flower with these pollinia sticking upright1 she would simply put them into the same slits in the next flower1 she would not touch them against the stigma4 ,nature1 however1 has provided against this4 ,as the bee flies along1 the glands sticking to its head dry more and more1 and as they dry they curl up and drag the pollen-masses down1 so that instead of standing upright1 as in #a1 ,fig4 #fc1 they point forwards1 as in #b4 ,and now1 when the bee goes into the next flower1 she will thrust them right against the sticky stigmas1 and as they cling there the fine threads which hold the grains together break away1 and the flower is fertilized4 ,if you will gather some of these orchids during your next spring walk in the woods1 and will put a pencil down the tube to represent the head of the bee you may see the little box open1 and the two pollen-masses cling to the pencil4 ,then if you draw it out you may see them gradually bend forwards1 and by thrusting your pencil into the next flower you may see the grains of pollen bread away1 and you will have followed out the work of a bee4 ,do not such wonderful contrivances as these make us long to know and understand all the hidden work that is going on around us among the flowers1 the insects1 and all forms of life8 ,i have been able to tell you but very little1 but ,i can promise you that the more you examine1 the more you will find marvellous histories such as these in simple field-flowers4 ,long as we have known how useful honey was to the bee1 and how it could only get it from flowers1 yet it was not till quite lately that we have learned to follow out ,sprengel's suggestion1 and to trace the use which the bee is to the flower4 ,but now that we have once had our eyes opened1 every flower teaches us something new1 and we find that each plant adapts itself in a most wonderful way to the insects which visit it1 both so as to provide them with honey1 and at the same time to make them unconsciously do it good service4 ,and so we learn that even among insects and flowers1 those who do most for others1 receive most in return4 ,the bee and the flower do not either of them reason about the matter1 they only go on living their little lives as nature guides them1 helping and improving each other4 ,think for a moment how it would be1 if a plant used up all its sap for its own life1 and did not give up any to make the drop of honey in its flower4 ,the bees would soon find out that these particular flowers were not worth visiting1 and the flower would not get its pollen-dust carried1 and would have to do its own work and grow weakly and small4 ,or suppose on the other hand that the bee bit a hole in the bottom of the flower1 and so got at the honey1 as indeed they sometimes do2 then she would not carry the pollen-dust1 and so would not keep up the healthy strong flowers which make her daily food4 ,but this1 as you see1 is not the rule4 ,on the contrary1 the flower feeds the bee1 and the bee quite unconsciously helps the flower to make its healthy seed4 ,nay more2 when you are able to read all that has been written on this subject1 you will find that we have good reason to think that the flowerless plants of the ,coal ,period have gradually put on the beautiful colours1 sweet scent1 and graceful shapes of our present flowers1 in consequence of the necessity of attracting insects1 and thus we owe our lovely flowers to the mutual kindliness of plants and insects4 ,and is there nothing beyond this8 ,surely there is4 ,flowers and insects1 as we have seen1 act without thought or knowledge of what they are doing2 but the law of mutual help which guides them is the same which bids you and me be kind and good to all those around us1 if we would lead useful and happy lives4 ,and when we see that the ,great ,power which rules over our universe makes each work for the good of all1 even in such humble things as bees and flowers2 and that beauty and loveliness come out of the struggle and striving of all living things2 then1 if our own life be sometimes difficult1 and the struggle hard to bear1 we learn from the flowers that the best way to meet our troubles is to lay up our little drop of honey for others1 sure that when they come to sip it they will1 even if unconsciously1 give us new vigour and courage in return4 ,and now we have arrived at the end of those subjects which we selected out of the ,fairy-land of ,science4 ,you must not for a moment imagine1 however1 that we have in any way exhausted our fairy domain2 on the contrary1 we have scarcely explored even the outskirts of it4 ,the ,history of a ,grain of ,salt1 ,a ,butterfly's ,life1 or ,the ,labours of an ,ant1 would introduce us to fairies and wonders quite as interesting as those of which we have spoken in these ,lectures4 ,while ,a ,flash of ,lightning1 ,an ,explosion in a ,coal-mine1 or ,the ,eruption of a ,volcano1 would bring us into the presence of terrible giants known and dreaded from time immemorial4 ,but at least we have passed through the gates1 and have learnt that there is a world of wonder which we may visit if we will2 and that it lies quite close to us1 hidden in every dewdrop and gust of wind1 in every brook and valley1 in every little plant or animal4 ,we have only to stretch out our hand and touch them with the wand of inquiry1 and they will answer us and reveal the fairy forces which guide and govern them2 and thus pleasant and happy thoughts may be conjured up at any time1 wherever we find ourselves1 by simply calling upon nature's fairies and asking them to speak to us4 ,is it not strange1 then1 that people should pass them by so often without a thought1 and be content to grow up ignorant of all the wonderful powers ever active in the world around them8 ,neither is it pleasure alone which we gain by a study of nature4 ,we cannot examine even a tiny sunbeam1 and picture the minute waves of which it is composed1 travelling incessantly from the sun1 without being filled with wonder and awe at the marvellous activity and power displayed in the infinitely small as well as in the infinitely great things of the universe4 ,we cannot become familiar with the facts of gravitation1 cohesion1 or crystallization1 without realizing that the laws of nature are fixed1 orderly1 and constant1 and will repay us with failure or success according as we act ignorantly or wisely2 and thus we shall begin to be afraid of leading careless1 useless1 and idle lives4 ,we cannot watch the working of the fairy life in the primrose or the bee1 without learning that living beings as well as inanimate things are governed by these same laws of nature2 nor can we contemplate the mutual adaptation of bees and flowers without acknowledging that it teaches the truth that those succeed best in life who1 whether consciously or unconsciously1 do their best for others4 ,and so our wanderings in the ,fairy-land of ,science will not be wasted1 for we shall learn how to guide our own lives1 while we cannot fail to see that the forces of nature1 whether they are apparently mechanical1 as in gravitation or heat2 or intelligent1 as in living beings1 are one and all the voice of the ,great ,creator1 and speak to us of ,his ,nature and ,his ,will4