anon seeming to relieve his feelings by stopping to pat my horse. At length I left my post, and dismounting, led my charger to the stable and handed it over to a comrade; then divesting myself of my cuirass, was ready to proceed to Scotland Yard. One of the corporals on guard received orders to accompany me; so, together with the gentleman, we started, and crossing the street, reached the police headquarters in a minute or two; and on making inquiries, were directed to the 'Lost Property' department. We stated our business; and an official, after receiving an assurance from me that the applicant was the right person, speedily produced the valise. 'Why didn't you see about this before?' he asked, addressing the gentleman.

'Because I was too ill to see about anything,' was the reply.

The gentleman then signed a book, certifying that his property had been restored to him, giving as he did so the name of Nobbs.

Having thanked the official, Mr Nobbs caught up his property, and we left the office. When we got to the door, we found assembled a small crowd of men employed about the establishment; for the unusual spectacle of two helmeted, jackbooted Guardsmen had caused a good deal of speculation as to our business there. Mr Nobbs hurriedly brushed past them, and gaining the street, hailed a passing cab, and the driver at once pulled up. 'Here is something for your trouble,' he said, slipping a sovereign into my hand. I, of course, thanked him heartily for this munificent douceur. Declining the offer of the driver to place his bag on the dicky, he put it inside the vehicle; then shaking hands with the corporal and myself, he said to the driver: Euston, as fast as you can,' and entered the cab.

The driver released the brake from the wheel, and was whipping up his scraggy horse with a view to starting, when the poor animal slipped and fell. The men belonging to Scotland Yard who had followed us into the street at once rushed to the driver's assistance, unbuckled the traces, and after pushing back the cab, got the horse on its feet. All the while Mr Nobbs was watching the operations from the window; and I noticed that one of the men was surveying him very attentively.

'Only some old clothes, I assure you,' said the crest-fallen Nobbs.

'Come inside, and we'll see,' said the detective, seizing the bag. 'Out of the cab-quick! and come with me to the office.'

Mr Nobbs complied with a very bad grace; while the corporal and I followed, wondering what was to happen next.

We entered a room in the interior, and the bag was opened; but it apparently contained nothing but the clothes.

"There is certainly no grounds for detaining the man,' said an inspector standing near.

Mr Nobbs at once brightened up and cried: 'You see I have told you the truth, and now be good enough to let me go.' 'Pack up your

'All right,' said the detective. traps and clear out!'

Mr Nobbs this time complied with exceeding alacrity, and began to replace the articles of clothing, when the detective, seemingly acting on a sudden impulse, caught up the valise and gave it a vigorous shake. A slight rustling sound was distinctly audible.

'Hillo! what's this?' cried the officer.Emptying the clothes out of the bag, he produced a pocket-knife, and in a trice ripped open a false bottom, and found-about two dozen valuable diamond rings and a magnificent emerald necklet carefully packed in wadding, besides a number of unset stones.

The jubilant detective at once compared them with a list which he took from a file, and pronounced them to be the entire proceeds of a daring robbery that had recently been committed in the shop of a West End jeweller, and which amounted in value to fifteen hundred pounds!

Mr Nobbs, alias Judd, now looking terribly confused and abashed at this premature frustration of his plan to clear out of the country with his booty, was formally charged with being in possession of the stolen valuables. He made no reply, and was led away in custody.

Before returning to the guard, I remarked to the inspector: I thought, sir, when he gave me a sovereign for looking after his bag that it was more than it was worth; but now I find that I have been mistaken.'

'A sovereign!' cried the inspector. 'Let me

see it.'

you've had a clean shave.' I started on hearing this statement; my suspicions, ridiculous as they seemed at the time, had turned out to be correct after all; while Mr Judd, alias Nobbs, turned as pale as death. 'Come out of that cab,' said the detective. 'You've no right to detain me,' said Nobbs. 'I was discharged this morning.'

Because nothing was known against you.-But look here, old man, what have you got in that bag?'

A few weeks after Mr Nobbs had received his well-earned punishment, I received a visit from a gentleman, who stated that he was cashier in the jeweller's establishment in which the robbery had been committed. He informed me that his employer, having taken into consideration the fact that I was to a certain extent instrumental in the recovery of the stolen jewellery, had sent me a present of thirty pounds. I gratefully accepted

the money, which, as I had seen enough of soldiering, I invested in the purchase of my discharge from the Household Cavalry. Such is my story of the Mysterious Valise.

TO MY BOY: AN APOSTROPHE.

I GAZE into the azure depths of thy bonnie eyes, my boy, and that gaze brings back to me other eyes and another form, long since mouldered to clay, and I feel bound to thee by a double tie. The childhood's love I bore that other is thine, and added thereto is a father's love, yearning and anxious. I can see in thy eyes the bygone days and years, which now are only memories vague and dim, like a diorama seen in dreams. There stand the two or three homely cottages which formed the hamlet where my boyhood's days were spent. There I see the greensward where my bare feet danced to untuned numbers. I again see the mossy bridge and the rippling brook. I hear the drone of the humble-bee, the grinding tune of the corneraik, and the hurried whir of the startled partridge. I can see the damp mists creep over the hills and sheet the valley in the gray twilight of the quiet summer evenings; and the flitting vision of the great white moths, which, in the gathering gloom, come out of shadow-land and again disappear. Sweeter than all the tunes I learned in these happy days, I hear my sister's and my mother's voice in happy hymnings again. There lie the 'lusty trout' that have just been emptied from my father's fishing-basket-the fruits of an evening hour. I see, by that old crumbling wall, the narrow strip of garden-ground that we shared among us, and where our near neighbours came to help.

Still

But gone to their graves, or scattered, are all the forms I loved so well. Many miles from where our lot is now cast are these treasured spots. The burn still tinkles on; but where are the men, women, and children I knew? the evening mists drape the valley with gray ; still the moths flit to and fro in the darkness. The old bridge is not greatly altered; but strangers may inquire in vain to whom belong those huge initials on the copestone, which we hewed out with a big nail and a stone one sweltering summer day. The wild-flowers bloom the same as ever; and in the early dawn may still be heard the familiar song of the skylark and the plaintive cry of the peewit-just as of old. But new forms fill the places of the old familiar ones, and I-I am a stranger where, for centuries, my forefathers dwelt and owned the land. The girls and boys are women now, and have become prisoners in smoky cities, there to toil for bread, and look back with a fond but unavailing regret to the quiet hamlet where they were born and bred. Some of them have escaped this fate, and slumber quietly in the still churchyard among the trees. One of them had thy gentle eyes, my son; and when thy gaze meets mine, the dead past rises before me, filling me with thoughts I cannot utter. Though a stranger in the land of my fathers, I see my brother in thy eyes, and in the eyes of every azure speedwell by the burnie's brim. I hear his voice in thine, and I hear it in every tumbling stream. He is gone, and you and I shall go into the

silent land' very soon; and still the busy world shall hurry on: the burn will not miss us; even our friends shall cease to miss us, for they, too, shall go.

MY LITTLE BOOK. A LITTLE book of sundry songs To me, who prize it much, belongs : Sweet songs are they of maid and youth, Of man and wife, of love and truth, Of bud and blossom, ear and sheaf, Of winter berry, summer leaf, Of orchard-blossoms in mid-May, Of fruitage golden, scented hay, Of shore and sea, of tarn and del!, Of haunted grange and holy well, Of Bacchus jovial 'mongst the grapes, And many another thing which shapes Itself with poet's brain and pen In songs that win the hearts of men.

My neighbour Fact, who keeps a school,
A model place of line and rule,
Who, the world's wise and prudent man,
Has not a thought without its plan;
Whose heart is captive to the head,
And by its calculations led,
While what escapes in love or thanks
Goes to the great per cents or banks,
He cares not for my little book,
But says 'twould neither keep a cook,
Nor pay the rent, nor buy a field,
Nor make the mine its ingots yield,
Nor add an eighth to dividend,
Nor introduce a wealthy friend.
In short, Fact says I am a fool
Whom sense has never put to school,
And that the race of rhymesters all,
Rank they the great ones or the small,
While they blow bubbles in the air,
Leave men to life's grand work and wear.

But I have friends, a chosen few,
Who love the good, and seek the true,
And know that men live not alone
In acres broad and piles of stone.
These often come, and with me look
For treasure in my little book.
Like bees we hie from flower to flower,
Lured on by sunshine of the hour,
We cluster round each favourite song,
And wish it were ten times as long,
And e'en when skies are dark and dull,
Each cell within our hive is full,
Nor gods themselves have daintier fare,
Or can than we be happier.
Ah! who is richer, Fact or I?
Whose rare estate he cannot buy,
Whose friends a life-long joy bespeak,
While his will change with every freak,
Whose wealth is sung in love and trust,
While his the wealth that turns to dust.
May I not thank my God that He
Has tuned my life to poesy?

B. W. PROVIS.

Printed and Published by W. & R. CHAMBERS, 47 Paternoster Row, LONDON, and 339 High Street, EDINBURGH.

No. 72.-VOL. II.

DUST.

ABOUT fourteen years ago, Professor Tyndall, when conducting some curious and interesting experiments into the purity of the atmosphere of various localities, had occasion to make use of a simple method of determining whether certain samples of air contained dust or not. By 'dust,' it should be explained, is meant any foreign floating particles, no matter what their nature may be. Having confined his air in a transparent glass, he placed it on a dark background in a darkened room, and allowed a ray of very powerful light to pass through it. When the air was free from dust, the ray within the vessel was invisible, the pure air remaining unilluminated; when, on the other hand, the air contained dust, the floating particles reflected more or less of the light, and the ray became visible as an illuminated band. He discovered that the ordinary atmosphere-such, that is, as is found close to the surface of the earth, and especially near cities and in dwelling-housesinvariably contains foreign bodies; that, in other words, it reflects light.

It was while carrying out these experiments that Professor Tyndall noticed a very remarkable phenomenon. If a heated body, such as a hot wire, be suspended in a glass that contains dusty air, and a ray of light be then passed through the vessel, the observer will remark that a dark, unilluminated aura at once rises about and above the wire; or, to speak otherwise, that, in the midst of the luminous dusty air, there is a transparent, unilluminated space, the core of which is the wire. In fact, streaming upwards, there is a body of air which is free from dust. The mounting of the air from the hot wire is explicable enough. The particles in immediate proximity to the wire become warmer, and, in consequence, lighter than the other particles; and therefore a current starts upwards from the hot surface. The then unsolved problem was: Why did this current contain no dust? The most natural conclusion seemed to be that the heated wire destroyed the dust that came 电

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into contact with it; and it may be that in certain cases this conclusion is a just one, for there are some kinds of dust-using the word in its widest sense-which heat may be said to annihilate. Floating particles of water and of fugitive salts, &c., come under this category; and Professor Tyndall appears to have temporarily accepted this explanation as applying to all kinds of dust. But it was in time demonstrated that this theory was incorrect. Three or four years ago, the provisional conclusions were upset by some further experiments of Lord Rayleigh, who for the hot wire substituted a wire of very low temperature, and observed that a downward current was then produced, and that this current, like the other one, was free from dust. The cold wire of course cooled the particles of air that came into immediate contact with it, and rendering them heavier than their neighbours, induced them to travel downwards. But why was the column dustless? It seemed incredible that the dust could have been destroyed by cold, as it had been supposed to be destroyed by heat. Some other explanation was obviously required; and the difficulty led scientific men to observe with greater attention than before the behaviour of dust in the neighbourhood of fixed bodies.

Experiments were made with vessels containing air which had been artificially loaded with floating particles. The burning of a piece of magnesium wire liberates a dense white cloud, consisting of minute atoms of magnesia. Charge a glass receiver with these fumes; suspend within the vessel a fragment of charcoal; and arrange matters in such a way that a strong ray of warm sunlight may be turned on to the charcoal and off again at will. If the observer suddenly turns on the ray, he will see that the fumes are dense throughout the vessel, and that these closely surround the charcoal, which, in fact, so long as it remains in the dark and at the same temperature as the surrounding air, has no influence upon the dust. But, in a few seconds, the sunlight will begin to warm the charcoal, and then the upward current of dustless air will become noticeable. First, a thin layer of

dustless air will be seen to form around the charcoal. It will be thickest on the side that is immediately exposed to the warmth; and it will rise gradually, until it constitutes the unilluminated aura, which was remarked by Professor Tyndall. As the observer watches, it will seem to him as if the charcoal drove away the dust from the approaching air. This cleansing process begins with the warming of the charcoal; and it is therefore tolerably clear that the warming of the charcoal is the cause of the phenomenon. This supposition is supported by the fact, that if the charcoal be warmed before its introduction into the vessel, and the ray be then turned on, it will be seen that the dustless, unilluminated aura has been already formed. It will also be remarked that the hotter the charcoal, the larger will be the aura. Indeed, in favourable circumstances, an aura with a minimum thickness of one-twentyfifth of an inch may be produced. Hot iron, glass, paper, or stone may be substituted for charcoal. Any of these, or even a heated surface of oil or water, will give the same results. From the warm body, a column of dustless air will be seen to rise. If a glass tube be passed through the body of the receiver, the phenomenon can be examined under the most favourable conditions; for the tube can then be charged with water of varying temperature; and it will be noticed that any increase of heat is immediately followed by an increase in the dimensions of the aura, and of the upward current of dustless air. If the tube be charged with ice, a downward current will set in, and, although no aura will be visible, and the tube itself will become dusty, the downward current will still be found to be free from dust.

The phenomena, strange as they are, are both explicable by reference to the mechanical laws of heat. According to the received theory, heat is the motion of the molecules of which all bodies ultimately consist. The molecules of air are always in lively motion; and the warmer the air, the more lively is that motion. If in a portion of air there be placed a body of a higher temperature, that body imparts a portion of its heat to the surrounding molecules of air, and, in consequence, increases the liveliness of their motion. In the immediate neighbourhood of the warmer body, therefore, the air molecules have two different motions. Those of them which have not touched the warmer body move with comparative slowness; whereas, those of them which have touched it move with accelerated speed away from it. And so, a particle of dust that chances to float somewhere near to the warm body is gently impelled towards it by the unaffected molecules, but more forcibly driven away from it by the molecules which have acquired new heat. The warmed molecules win the day; and, naturally, the particle of dust being unable to overcome them, does not approach the warm body. Such is the position of things so long as the body remains warmer than the air in which it has been placed; and such is the explanation of the dustless aura that surrounds warm bodies. The lighter a gas is, the more vigorous is the motion of its molecules. In hydrogen, therefore, a larger dustless aura may be produced than in atmospheric air; and, similarly, under the halfexhausted receiver of an air-pump, a larger aura may be produced than is possible under normal

conditions. When a body of a temperature lower than that of the surrounding air is introduced into the receiver, the strife between the two classes of air-molecules has a different result. The molecules which have touched the cold body have their temperature lowered, or, in other words, their activity lessened. They are driven back by the superior vigour of the others; and the particles of dust that are floating in the air are, in consequence, carried close to the cold body and forced against it. They remain on its surface, and the air in which they floated is cooled, and falls, by virtue of its weight. Such is the expla nation of the downward dustless current. To sum up: bodies which are warmer than their surroundings, visibly drive off dust; and those which are colder, visibly attract it. These are the special principles, which, modified, of course, by the operation of the various natural forces, regulate the deposit of floating particles from the atmosphere.

The

But there is yet another kind of body which has a remarkable influence upon dust, and, through dust, upon moisture in the air. introduction into a dusty atmosphere of a body highly charged with electricity produces a new phenomenon. In order to observe it, let an electrical machine in action be so arranged that its conductor shall be charged with positive electricity, while the negative current goes to the earth; and then let the room be filled with dust. The influence of the conductor will make itself felt over a large cubic space in the following manner. In normal circumstances, every particle of dust contains equal portions of positive and negative electricity. The positive conductor, however, attracts negative electricity and repels positive. The particles, therefore, become posi tive on one side and negative upon the other. If two particles of dust, while in this condition, approach one another, the negative electricity of the one will attract the positive electricity of the other; and the two particles will, in consequence, cleave together, and form a larger particle, which, in turn, at once becomes positive on one side and negative on the other. There are thus continual additions of particles; and when the aggregations of dust become large, they sink by their own weight to the ground. The pres ence, therefore, of highly electrified bodies hastens the deposit of dust.

It has been proposed to utilise this law in order to free London from the soot and fog which, especially at certain seasons, enshroud her. It seems to be established that a London fog owes its existence to the immense quantity of dust which is created by the myriad chimneys and the ten thousand manufactories of the metropolis; and the way in which the yellow fog is supposed to form is curious. When a particle of dust is afloat in a damp atmosphere, some of the moisture condenses on it, and it becomes the nucleus of an 'atom' of fog. The weight of the particle is thus increased; and the water-logged dust floats low. The result is that the humidity is denser than it would be if it were unladen with so much dust, and that it is darker and more opaque in proportion to the amount of dust that it contains. If we had less dust and soot, we should have less of this pall-like fog; and if we could precipitate some of our dust, we should diminish our