ton in the vicinity of their gin." Near the close | large farmers to work their slaves

of this letter the writer says: "There might be thousands of bales of free cotton collected through this country, but for the ginning and packing, or baling."

"Yalabusha Co. (Miss.) 12th mo. 30, 1848. "The writer states that about 100 bales of free cotton may be obtained in one neighbourhood, and that a gin, to be managed by free labour, is likely to be erected by "men of small or middling property, but firm and fixed principles, and whose reputation for piety stands high with

large portions of it are already completed-there being no doubt that the whole structure will be at no distant period fixed, and in full work-yet as the Conway Tube is the only one which is perfected as yet, and upon which actual working has commenced, we shall confine our account to this alone. But it may be inentioned that both of these tubular bridges-although the one at Conway is inferior in proportions and in weight to the Britannia--are constructed on similar principles, and are in other respects alike, both in their object and form, and in the mechanical adjustment by means of which they are placed in situ.

ditions of strength and lightness. Having so
far satisfied himself on these points, he con-
structed a model tube on a large scale, contain-
ing nearly all the features of the proposed bridge.
The form of a circular tube was found defective
in many respects, and the idea of constructing
the bridge of that form was soon abandoned.
Tubes were also constructed of elliptical and
rectangular forms, with various results. Even-
tually a square tube was decided upon; and the
investigations were now continued, to evolve the
principles upon which this form might be ren-
dered of sufficient strength to resist vertical and
lateral violence. At first, Mr. Fairbairn con-
ceived that the strongest form would be one in
which the top and bottom of the tube consisted
of a series of pipes arranged in a hollow com-
partment, covered above and below by iron
plates rivetted together, and having a parallel
direction to the long axis of the tube.
By this
means great rigidity would be communicated to
the top, to resist the immense compression it
would necessarily endure; and the bottom would
be equally strong, to resist the tension which it
would be subject to. And this form would pro-
bably have been adopted, but for several serious
practical difficulties which presented themselves
to its construction, and to its repair, if accidentally
damaged.

The idea of a tube bridge is one of those original conceptions which are the birth, not of an individual's life, but of an era, It is one of those truly unique and rare productions--a new and valuable fact. No one appears to have dreamed of such a thing before. Ingenious people, who take an unkind pleasure in pulling down the high fame of others, have found, as they imagine, the originals of suspension bridges in the rude contrivances of American Indians to cross a gully; but no one can point to a tube bridge as the invention of any time or country but our own. If, therefore, it can be truly shown that not only has a novel system been discovered, but also that it possesses such advantages in an engineering point of view as are The model tube, the form of which was to be possessed by none other previously discovered, adopted in the large scale, was finally formed of Mr. Stephenson the engineer, may be pointed to a square shape, with longitudinal cellular comas one of those illustrious men in whom apartments, also square, at the top and bottom. happy union of originality of talent, with indomitable patience in working out its conceptions, has largely added to the resources of science, and, by necessary consequence, largely benefited the human race. All sorts of forebodings, and these, as indeed is only too commonly the case, from men of pre-eminent practical skill and scientific attainments, foretold certain failure to the daring enterprise which proposed to cast a huge tube over a strait, that men might travel in security through its interior. The proposition also to construct this great aërial tunnel of wrought iron was entirely novel, and it remained for time, experience, and experiment, to show its applicability to the purpose in question.

The scale was exactly one-sixth of the bridge across one of the spans of the Menai Straits; it was also one-sixth of the depth, one-sixth of the width, and as nearly as possible, one-sixth of the thickness of the iron plates. Thus it was eighty feet long, four feet six inches deep, two feet eight inches wide, and rested on two supports, the distance between which was seventyfive feet. The entire weight of this large model was between four and five tons. It was now subjected to the severe experiments which were to test its strength. The weight was attached to its centre, and increased ton by ton, the deflection being carefully noted, together with the entire weight of the load. After three experiments, in which various defects were discovered, the conFrom what we have been able to gather, it ap-clusion arrived at, of the extreme point of repears that Mr. Robert Stephenson at first conceived the idea that a tube bridge of the circular form would be the strongest; but being unable, in consequence of numerous professional avocations, to undertake personally to carry out the requisite experiments, he committed this important task to the able hands of Mr. Fairbairn of Manchester, under his own immediate inspection. Much credit is due to this distinguished mechanist for the experiments which he instituted with a view to ascertain the proper principles on which to compose such a structure, particularly with respect to the two grand con

sistance of the model tube placed it at about fifty-six tons; in other words, its breaking weight was 56.3 tons. This result proved highly satisfactory, and exhibits in a remarkable manner the extraordinary resistance offered by a tube of this construction to a load more than eleven times its own weight. Mr. Fairbairn adds, that it is probably not overrating the resisting powers of this tube to state that hollow beams of wrought iron,

*Some claims have been made for Mr. Fairbairn with

regard to the invention of the Tube Bridge. We feel it to be our duty merely to intimate the fact.

constructed on the same principle, will be found, | Six immense pontoons, one hundred feet long, whether used for bridges or buildings, about three and of proportionable breadth and height, were times stronger than any other description of then hauled up to the platform, and floated, girders. The principles for the construction of three at each end of the tube underneath it: they the great bridge were thus satisfactorily deter- were properly lashed together, and secured. mined, and the accuracy of the engineer's con- High tide served a little after eleven in the forejectures as to this method of bridge-building was noon; all things were therefore got ready to take fully established. full advantage of this circumstance. As the tide rose higher and higher, the feverish anxiety of the spectators and parties concerned rose in geometric progression. The great pontoons rose too, until they touched the bottom of the tube, and began to bear up its tremendous weight The favourable moment having arrived, the pumps were set to work, and the pontoons emptied of a large volume of water purposely introduced into them. As this water was discharged, they rose higher and higher, until at length, to the vast relief of a crowd of spectators, the immense mass floated clear off the platform on which it had rested for a whole year. It was still some distance from its resting-place; but the sides being properly shoved up, the whole structure--with the chief, the assistant, and the resident engineers standing together, with two or three other gentlemen, in a sort of triumphal position upon its summit-was set in motion by means of strong hawsers worked by capstans, and attached to different places. It was guided in its slow career by chains connected with buoys placed at intervals in its route. At length it was dragged to its proper position; and resting under the receding influence of the tide upon two stone beds prepared for its reception on each side, it now appeared as a great unwieldy box crossing the transparent waters of the river, and offering a barrier to navigation. All this momentous operation was the work of a few hours, and was conducted with the most complete success.

In the early part of 1847, the Conway Tube Bridge was commenced. Those who are familiar with the picturesque scenery of the river Conway will readily remember the romantic position of the Suspension Bridge. The site for the new bridge is very near it, the one end abutting against the foot of the venerable ruin, whose time-defying towers rear themselves above it; the other resting on an artifical structure, of a castellated aspect, on the opposite side of the river, from whence the railway shoots into the interior of the country. The site of the bridge was not, however, convenient for the purpose of constructing the tube; and advantage was consequently taken of a less percipitous part of the river's bank, about a hundred yards or so from the permanent position of the bridge. There, upon a piece of level ground projecting some distance into the river, workshops and a steamengine were erected, and an immense platform constructed on piles driven into the ground, and partly into the bed of the river, and forming a temporary pier. At high water, the tide was nearly level with the bottom of the tube. Altogether, about twelve months were occupied in the construction of the tube. When completed, and resting on its massive platform, with the crowds of busy workmen, the clattering of hammers, the hum of the workshop, the fuming chimney, the vast pontoons, all contributed to make the scene one of the most interesting and anomalous that was ever witnessed; especially when the peculiarity of the situation is remembered-the calm river floating idly by, and the old castle, the work of hands long since crumbled to dust, and of instruments long since eaten to rust, looking, as it were, in astonishment on the whole; while a crowd of Welsh peasants incessantly gaped with amazement at the idea of putting a long iron chest over their ancient river. The tube was at length complete; and now remained the Herculean undertaking of dragging it to its position, and lifting it up to its proper elevation. This was the most anxious and arduous task of all. What if the cumbrous mechanism contained some hidden defects? What if, when being lifted, something were to give way, and the vast structure come down, and crush itself and everything before it into a heap of ruins? Not only fame, but life and property, hung upon the skill of one or two men. On Monday, March 6th, 1848, the great experiment was made. The tube had been made to rest upon two temporary stone piers, by the removal of some of the piles supporting the platform on which it was built.

[To be continued.]

SLAVERY AND IGNORANCE.
Extracts from a speech of Horace Mann, of
Massachusetts, in the House of Representatives,
at Washington, 6th month, 30th, 1848.

It was not the design of Providence that the work of the world should be performed by muscular strength. God has filled the earth and imbued the elements with energies of greater power than all the inhabitants of a thousand Whence come our necessaplanets like ours.

ries and our luxuries?—those comforts and appliances that make the difference between a houseless, wandering tribe of Indians in the far West, and a New England village? They do not come wholly or principally from the original, unassisted strength of the human arm, but from the employment, through intelligence and skill, of those great natural forces, with which the bountiful Creator has filled every part of the material universe. Caloric, gravitation, ex

pansibility, compressibility, electricity, chemical affinities and repulsions; spontaneous velocities; these are the mighty agents which the intellect of man harnesses to the car of improvement. The application of water and wind and steam to the propulsion of machinery, and to the transportation of men and merchandise from place to place, has added ten thousand fold to the actual products of human industry. How small the wheel which the stoutest laborer can turn, and how soon will he be weary! Compare this with a wheel driving a thousand spindles or looms, which a stream of water can turn, and never tire. A locomotive will take five

by a hundred thousand men--to saw timber, to make cloth, to grind corn-and they obey. Ignorant slaves may stand upon a coal mine, and to them it is only a worthless part of the inanimate earth. An intelligent man uses the same mine to print a million of books. Slaves will seek to obtain the same crops from the same field, year after year, though the pabulum of that crop is exhausted; the intelligent man with his chemist's eye, sees not only the minutest atoms of the earth but the imponderable gases which permeate it, and he is rewarded with a luxuriant harvest.

Nor are these advantages confined to those departments of nature where her mightiest forces are brought into requisition. In accomplishing whatever requires delicacy and precision, nature is as much more perfect than man, as she is more powerful in whatever requires strength. Whether in great or in small operations, all the improvements in the mechanical or the useful arts come as directly from intelligence, as a bird comes from a shell, or the beautiful colors of a flower out of sunshine. The slave-worker is forever prying at the short end of Nature's lever; and using the back, instead of the edge, of her finest instruments.

hundred men, and bear them on their journey hundreds of miles in a day. Look at the same five hundred men, starting from the same point and attempting the same distance, with all the pedestrian's or equestrian's toil and tardiness. The cotton mills of Massachusetts will turn out more cloth in one day than could have been manufactured by the inhabitants of the Eastern continent during the tenth century. On an element which in ancient times was supposed to be exclusively within the control of the gods, and where it was deemed impious for human power to intrude; even there the gigantic forces of nature, which human power and skill have enlisted in the service, confront and all departments of human industry, that uneduThe most abundant proof exists, derived from overcome the raging of the elements-breasting cated labour is comparatively unprofitable tempests and tides, escaping reefs and lee shores, labour. I have before me the statements of a and careering triumphant around the globe. number of most intelligent gentlemen in MassaThe velocity of winds, the weight of waters, chusetts, affirming this fact as the result of an exand the rage of steam, are powers, each one of which is infinitely stronger than all the strength sachusetts we have no native born child wholly perience extending over many years. In Masof all the nations and races of mankind, were it without school instruction; but the degrees of all gathered into a single arm. And all these attainment of mental development, are various. energies are given us on one condition-the Half a dozen years ago, the Massachusetts Board condition of intelligence-that is, of education. of Education obtained statements from large Instead of iron arms, and Atlantean shoul- numbers of our master mauufacturers, authentiders, and the lungs of Boreas, our Creator has catea from the books of their respective estabgiven us a mind, a soul, a capacity of acquiring fishments, and covering a series of years, the knowledge, and thus of appropriating all the result of which was, that increased wages were energies of nature to our own use. Instead of found in connection with increased intelligence, a telescopic and microscopic eye, he has given just as certain as increased heat raises the therus power to invent the telescope and the mi-mometer. Foreigners, and those coming from croscope. Instead of ten thousand fingers, he has given us genius inventive of the power loom and the printing press. Without a cultivated intellect, man is among the weakest of the dynamical forces of nature; with a cultivated intellect, he commands them all.

And now, what does the slave-maker do? He abolishes this mighty power of the intellect, and uses only the weak, degraded, half animated forces of the human limbs. A thousand slaves may stand by a river, and to them it is only an object of fear and superstiton. An intelligent man surpasses the ancient idea of a river god; he stands by the Penobscot, the Kennebec, the Merrimac, or the Connecticut; he commands each to do more work than could be performed

other States who made their marks when they receipted their bills, earned the least; those who had a moderate or limited education, occupied a moderate or limited ground on the pay-roll; while the intelligent young women who worked in the mills in winter, and taught schools in summer, crowned the list. The larger capital in the form of intelligence yielded the larger interest in the form of wages. This inquiry was not confined to manufactures, but was extended to other departments of business, where the result of labour could be made the subject of exact measurement.

This is universally so. The mechanic sees it when he compares the work of a stupid with that of an awakened mind. The traveller sees

it, when he passes from an educated to an un- | educated nation.

This difference is most striking in the mechanic arts; but it is clearly visible also in husbandry. Not the most fertile soil, not mines of silver and gold, can make a nation rich without intelligence. Who ever had a more fertile soil than the Egyptians? Who have handled more silver and gold than the Spaniards? The universal cultivation of the mind and heart is the only true source of opulence; the cultivation of the mind, by which to lay hold on the treasures of nature; the cultivation of the heart, by which to devote those treasures to beneficent uses. Where this cultivation exists, no matter how barren the soil or ungenial the clime, there comfort and competence will abound; for it is the intellectual and moral condition of the cultivator that improves the soil, or makes it teem with abundance.

illumine the whole land. They would be
schools, too, in point of cheapness, within every
man's means. The degrading idea of pauper
schools would be discarded forever. But what
is the condition of Virginia now? One-quarter
part of all its adult free white population are
unable to read or write; and were proclaimed
so by a late governor, in his annual message,
without producing any reform. Their remedy
is to choose a governor who will not proclaim
such a fact. When has Virginia, in any state
or national election, given a majority equal to
the number of its voters unable to read or write?
-A republican government, supported by the
two pillars of slavery and ignorance!
[To be continued.]

THE RESPONSIBILITY.

A few evenings since we heard a young genBut slavery makes the general education of tleman from Virginia deliver an eloquent address, the whites impossible. You cannot have a in which he related the following thrilling incigeneral education without common schools. dent. A young friend of his had become sadly Common schools cannot exist where the popu- intemperate. He was a man of great capacity, lation is sparse. Where slaves till the soil, or fascination and power, but he had a passion for do the principal part of whatever work is done, brandy which nothing could control. Often in the free population must be sparse. Slavery, his walks he remonstrated with him, but in vain; then, by an inexorable law, denies general edu- and as often, in turn, would his friend urge him cation to the whites. The Providence of God to take the social glass in vain. On one occasion, is just and retributive. Create a serf-caste and he agreed to yield to him, and as they walked debar them from education, and you necessarily up to the bar together, and the bar-keeper said, debar a great portion of the privileged class from "Gentlemen, what will you have?" Wine, sir, education, also. It is impossible in the present was the reply. The glasses were filled, and the state of things, or in any state of things which two friends stood ready to pledge each other in recan be foreseen, to have free and universal edu-newed and eternal friendship, when he paused cation in a slave state. The difficulty is insurmountable. For a well organized system of common schools, there should be two hundred children, at least, living in such proximity to each other that the oldest of them can come to gether to some central school. It is not enough to gather from within a circle of half a dozen miles diameter, fifty or sixty children for a single school. This brings all ages and studies into the same room. A good system requires the separation of school children into four, or at least into three classes, according to ages and attainments. Without this gradation, a school is bereft of half its efficiency. Now, this can never be done in an agricultural community, where there are two classes of men-one to do all the work, and the other to seize all the profits. With New England habits of industry, and with that diversified labour which would be sure to spring from intelligence, the State of Virginia could support in abundance the whole population of New England. With such a free population, the school children would be so numerous that public schools might be opened within three or four miles of each other, all over its territory-the light of each of which, blending with its neighbouring lights, would

and said to his intemperate friend" Now, if I drink this glass aud become a drunkard, will you take the responsibility?" The drunkard looked at him with severity, and said, "Set down that glass." It was set down, and we walked away without saying a word. O, the drunkard knows the awful consequences of the first glass. Even in his own madness for liquor, he is not willing to assume the responsibility of anoher's becoming a drunkard. If the question were put to every dealer as he asks for his license, and pays his money-"Are you willing to assume the responsibility?" how many would say, if the love of money did not rule, "Take back the license."-Jour. Amer. Temp. Union.

NIGHT WAKING PREVENTED.

When John Wesley, the founder of the Methodist Society, was a young man, he found the habit growing upon him of waking at twelve or one o'clock in the night, and lying some time awake. This led him to apprehend that he was spending more time in bed than nature required. He therefore adopted the necessary means of breaking his morning slumbers at seven instead of eight, which had been his hour of rising. But