it is the practical evaporating power. The theoretical evaporating power varies with the quality of the fuel. A given weight of certain species of coal will evolve in combustion a greater or less quantity of heat than other species. In general, it may be stated that the strongest coals, meaning by that term those which have the greatest evaporating power, are those which are richest in carbon. The practical evaporating power of a given species of coal varies with the form, construction, and magnitude of the furnace and boiler. That portion of the heat which does not reach the water is dissipated in various ways. A part of it is lost by radiation from the grate; a part by radiation from the boiler; a part is carried by the heated gases of combustion into the chimney. The first two sources of waste of heat are reduced to a very small amount by a variety of ingenious contrivances. But the last is indispensable to the maintenance of the combustion, and ought to be considered as the power by which the furnace is worked, rather than a waste of heat.

The grate upon which the fuel is placed is surrounded on every side by parts of the boiler, within which water is contained. In some boilers, even the ash-pit is a part of the surface of the boiler, under which there is water. In this case, all the heat radiated from the grate, and the fuel upon it, is transmitted to the boiler; and in all cases the furnace is surrounded on every side, except the bottom of the grate or ash-pit, with surfaces having water within them.

The waste of heat by radiation from the surfaces of the boiler, steampipes, cylinder, and other parts of the machinery in which steam is contained, or through which it passes, is diminished by various expedients, which in general consist in surrounding such surfaces with packing, casing, or coating, composed of materials which are non-conductors, or at least very imperfect conductors of heat. In some cases the boiler is built round in brick work. In marine boilers it has been the practice recently to clothe the boiler and steam-pipes with a coating of felt, which is attended with a similar effect. When these remedies are properly applied, the loss of heat proceeding from the radiation of the boiler is reduced to an extremely small amount.

The circumference of the earth measures twenty-five thousand miles; if it were be

girt with an iron railway, a train carrying two hundred and forty passengers would be drawn round it by the combustion of about three hundred tons of coke, and the circuit would be accomplished in five weeks.

The enormous consumption of coals produced by the application of the steam engine in the arts and manufactures, as well as to railways and navigation, has of late years excited the fears of many as to the possibility of the exhaustion of our coal-mines. Such apprehensions are, however, altogether groundless. If the present consumption of coal be estimated at sixteen millions of tons annually, it is demonstrable that the coal-fields of this country would not be exhausted for many centuries.

But in speculations like these, the probable, if not certain progress of improvement and discovery ought not to be overlooked; and we may safely pronounce that, long before such a period of time shall have rolled away, other and more powerful mechanical agents will supersede the use of coal. Philosophy already directs her finger at sources of inexhaustible power in the phenomena of electricity and magnetism. The alternate decomposition and recomposition of water, by electric action, has too close an analogy to the alternate processes of vaporization and condensation, not to occur at once to every mind: the development of the gases from solid matter by the operation of the chemical affinities, and their subsequent condensation into the liquid form, has already been essayed as a source of power. In a word, the general state of physical science at the present moment, the vigor, activity, and sagacity with which researches in it are presented in every civilized country, the increasing consideration in which scientific men are held, and the personal honors and rewards which begin to be conferred upon them, all justify the expectation that we are on the eve of mechanical discoveries still greater than any which have yet appeared; that the steam engine itself, with its gigantic powers, will dwindle into insignificance in comparison with the energies of nature which are still to be revealed; and that the day will come when that machine, which is now extending the blessings of civilization to the most remote skirts of the globe, will cease to have existence except in the page of history.

OLD BOGIE.

blood, where the ogre's dead wives were dangling by the hair. We saw plainly the

little ones to whom love ministers, and whose fears are not excited by fancied horrors or imaginary monsters. And yet childhood is naturally fearless. It is education-sadly misapplied word! but it is education that makes cowards. Note, for illustration, the boldness with which children will fondle animals; the confidence with which a little boy will throw his arms about a Newfoundland dog. These are characteristics with which tutors of the young idea should not deal too lightly. Yet how soon is fear created in the child. How soon is its wild imagination led to objects of horror that fasten upon it, and become to it irresistibly fascinating! The story of Old Bogie is, alas! a household story-the religion of every nursery. The grim monster presents himself behind a sheet elevated upon a broom-stick, or crouching in a corner, when the gloom of evening leaves broad black shadows in the room. Then are children gathered about | the fire, huddled around the nurse's knee, while she relates his wondrous adventures; how, once upon a time, he carried off a little boy who would not go to bed when his mamma told him; how he ate another child who would not learn his letters; how he came with a big bag to a third, and, seeing that the little fellow declined to take the Saturday bath-that weekly misfortune which children dreadput him into the bag, and took him, screaming, away upon his broad shoulders. And then the children, while listening to these awful histories, glance at the dark corners of the room, and clutching still tighter at the nurse's gown, vow that they will be good; that they will go to sleep directly they are put to bed; that they will never cry again; that they will be model scholars.

There is a fascination in their fright, and they eagerly ask for other stories equally terrible. Then comes Old Bogie's great son, Blue-Beard. His is a charming story for children! His blue beard; his keys dangling at his waist; his cimeter; his rolling eyes; do we not all remember them as making up perhaps the earliest image that held fast our young imaginations? We read or still, while the book trembled in our hands, to the chamber of

appeared! But the blood lingered in our memories. That clotted key has cost us many a wakeful moment at the dead of night, even when the clothes have been heaped over our head. A worthy son of Old Bogie was Blue-Beard to us; nor have we much fault to find, on the score of blood, in Jack the Giant-Killer. To be sure, the little fellow is a brave fellow; and there is some kind of rough justice in his career; but it is all blood. Nor are the experiences of his good, timid little cousin, Red Riding Hood, more acceptable to our judgment now. That hungry wolf that ate up the little girl's grandam, and subsequently invited the child to lie beside him, made no mean figure in our gallery of monsters. We had our gallery full; in short, a demon at our elbow always. And what cowards they were! Did they not come to us always in that terrible dark? As soon as the light faded from the heavens and objects lost their outline, how wildly did our imaginations set forth on their fearful journey. On no account could we suffer one moment's solitude. Did the nurse leave the room simply to fetch fuel, did we not cling to her apron, even while she scolded us bitterly for our cowardice? And then, when she opened that black place, the coal-cellar, and she playfully asked us whether it did not resemble Blue-Beard's shambles; did not the plaything we held drop among the coals, and were we not too terrified to pick it up? And did not the nurse, seeing our fear, call out that Old Bogie was there, and did we not scamper off in horror? It was a powerful influence that nurse had over us ever afterward. Not she, but Old Bogie, governed us. Did we soil our blouse in the garden, Old Bogie would certainly visit Did we play with the fire, he would come down the chimney. Through our fear, our craven fear, we were led captives.

us.

limitless kindness, and hope to see it presently in practice. There is a tyranny in the world from which our grand-children will not be emancipated, because it rests in the selfishness and in the pride of men. Deep and subtle as parental love is, it is soon reconciled to the shifts which selfishness imposes upon children, and to the hard laws with which pride rules them. For the sake of quiet, in the quest of economy, how soon is the father ready to turn his child from home, to the care of a stranger! He cheats himself generally into the belief that he is sorry to part with his child, but that the step is for its ultimate good. More, his mother is spoiling him. True, the poor mother may have worked upon the child's fears to keep it quiet; true, she may have created in its mind a horror of our old friend and tutor, Bogie; but has she not, too, held it to her bosom? It will run to fetch mamma's scissors with a nimbler foot than that which follows the paternal orders; for the father is but a mild form of Bogie-a Bogie tempered with occasional flashes of kindness. If there be punishment to inflict, it is he who chastises. If there be a lecture to deliver, his deep voice pronounces it; and the child listens very gravely. This is, we are told, proper respect for the parent-the duty of the child to the father.

But what if we say that the child, when it comes into the world, owes the parent no duty whatever; that what we call duty is simply bondage; if we assert that the true and only duty due from the child, is its acknowledgment of the parental love that may be lavished upon it. But suppose no love warms its childhood-suppose that the father mistakes stern authority for parental dignity-is the child a debtor for its mere existence? "Non est bonum vivere, sed bene vivere," said Seneca. And he declared that he who gave him nothing more than life, gave him only what a fly or a worm might boast. Well, is he a benefactor to the child or to the state, who nurses the child's fears and works upon them chiefly? In no sense. Constant fear degrades the moral sense. It is the basest of all influences; it chops the fingers of the dying wretch overweighting the raft; it turns crowds into wild animals, even in a place of worship. Yet, Old Bogie is our witness that fear is brought to our children's cradles. We,

men and women, are their slave-owners. We whip them, imprison them, reduce their allowance of food, and, strange perversity of nature, they grow up ungrateful!

TO-DAY AND TO-MORROW.

HIGH hopes that burn'd like stars sublime,
Go down i' the heavens of Freedom,
And true hearts perish in the time
We bitterliest need 'em!
But never sit we down and say

There's nothing left but sorrow;
We walk the wilderness to-day,

The Promised Land to-morrow.

Our birds of song are silent now,

There are no flowers blooming, Yet life beats in the frozen bough,

And Freedom's spring is coming! And Freedom's tide comes up alway,

Though we may strand in sorrow; And our good bark, aground to-day, Shall float again to-morrow.

Through all the long, dark night of years,

The people's cry ascendeth,

And earth is wet with blood and tears,
But our meek sufferance endeth!
The few shall not forever sway,

The many moil in sorrow;
The powers of hell are strong to-day,
But Christ shall rise to-morrow.

Though hearts brood o'er the past, our eyes
With smiling features glisten!

For lo! our day bursts up the skies!
Lean out your souls and listen!
The world rolls Freedom's radiant way,
And ripens with her sorrow:
Keep heart! who bear the cross to-day
Shall wear the crown to-morrow.

O youth flame earnest! still aspire,
With energies immortal,
To many a heaven of desire

Our yearing opes a portal!
And though age wearies by the way,
And hearts break in the furrow,
We'll sow the golden grains to-day;
The harvest comes to-morrow.

Build up heroic lives, and all

Be like a sheathen'd saber, Ready to flash out at God's call, O chivalry of labor ! Triumph and toil are twins, for aye Joy suns the cloud of Sorrow, And 'tis the martyrdom to-day Brings victory to-morrow.

NEVER regret an act of generosity, however worthless the object. If you act nobly to one that deserves nobly, you confer a benefit on him and yourself; if he be undeserving, still the very action does good to your own heart.

THE

LITTLE BRIDGET.

HE correspondent to whose graceful pen the NATIONAL is indebted for a series of articles on Humane Institutions, has given several biographical sketches of those who, in God's inscrutable providence, have come into this weary world without those faculties, in possession of which most of us rejoice. The deaf, and the dumb, and the blind, have excited our warmest sympathies. The various forms of insanity, and the philanthropic means used for its alleviation, have also been described in former pages. There is another large class of our fellow-creatures, the silly, the half-witted, who pass through life, too frequently the mere sport of the thoughtless, and who, nevertheless, have warm hearts, and whose lives might, by a little care, be rendered, if not happy, at | least not altogether wretched. Read the simple account which follows, from the pen of a German philanthropist.

Little Bridget, when I first saw her, was no longer quite a child, being already thirteen years of age; but she was very little and a sad cripple. Judging from her height, you would have taken her for six or seven. She was very deaf, spoke most unintelligibly, was most painfully deformed, and her face looked as if it belonged to a person of forty years of age. She always appeared very serious and ill-tempered, I had almost said morose; and if she did occasionally smile, it had such a painful appearance that one hardly knew whether to grieve or to rejoice.

Her parents were poor people; and one day, as I entered their cottage to offer her father a job of work, I saw Bridget standing amid a merry, rosy-cheeked group of her brothers and sisters. I was so startled by her appearance that I had almost forgotten the object of my visit, and could only stand staring at the poor little girl's old wizened-looking face.

"Yes," said Bridget's mother, who seemed to guess the current of my thoughts, "that child is a sad trouble; she is nearly thirteen, and can neither read nor say her prayers. At school they can do nothing with her, and I have no time to devote to her; so, you see, she grows up any how; though, goodness knows, one cannot exactly say that she grows."

The little one, perhaps, understood a great part of this speech, for she retired

with dignified ill-humor into a corner of the window.

She

"Yes," continued the mother, "what is to become of her I don't know. can do nothing, and she has learned nothing. It is a sad thing when the two come together."

"Is she a good child?"

"Good? well, I hardly know myself; I have so little time, and she doesn't talk much, but goes her own way. She does not beat her brothers and sisters; I must say that; and when I ask her to do anything that she can do, peel potatoes, or anything of that sort, she does it without any objection, and is very industrious about it; but, at the same time, most dreadfully slow.".

I looked, with unspeakable compassion, at the poor little thing; it grieved my heart to look, and yet I could not help doing so. I gave a small piece of money to each of the children, simply for the sake of an excuse for giving a trifle to Bridget. When her mother called her to me, she gave me a disdainful look, held out her hand sullenly, and muttered a few words, which I did not understand; if it was a "thank you," it was, at any rate, an unfriendly one. I went away, but the image of the little one went with me. I could think of nothing but that miserable, old-looking face, and the gray eyes that had been fixed upon me so scrutinizingly. In a few days I had arranged my plans; I begged Bridget's parents to confide the child to me, and, taking her to my country estate, placed her under the village schoolmaster, who had an excellent wife, and was himself a very good man.

In three years' time Bridget had acquired some notion of religion-as much, perhaps, as was requisite for her; she could read and write too, but no one understood what she read. I called often to see her she had gradually become accustomed to me; I often praised her; and when I first told her that she was a sensible little girl, to whom a great deal could be trusted, she smiled gratefully and joyously.

I reflected a long time upon the position that Bridget seemed fitted to fill in the world; at last I discovered a suitable occupation, and, after the expiration of those three years, took her on to the estate, and gave her the charge of all the poultry. The employment seemed made for her;