London, Friday, June 6, 1851.

The great "Exposition" (as the French more accurately term it) has now been more than five weeks open, and is nearly complete. You may wander for miles through its richly fringed avenues without hearing the sound of saw or hammer, except in the space allotted to Russia, which is now boarded up on all sides, and in which some twenty or thirty men are at work erecting stands, unpacking and arranging fabrics, &c. I visited it yesterday, and inferred that the work is pushed night and day, since a part of the workmen were asleep (under canvas) at 2 o'clock. This apartment promises to be most attractive when opened to the public. Its contents will not be numerous, but among them are very large and showy manufactures of Porcelain, Bronze, &c., and tables of the finest Malachite, a single piece weighing (I think) nearly or quite half a ton. Not half the wares are yet displayed, but "Russia" will be the center of attraction for some days after it is thrown open.

The Exhibition has become a steady, business-like concern. The four "shilling days" of each week are improved and enjoyed by the common people, who quietly put to shame the speculation of the Aristocratic oracles as to their probable behavior in such a magazine of wealth and splendor—whether they might not make a general rush on the precious stones, plate and other valuables here staring them in the face, with often but a single policeman in sight—whether they might not refuse to leave at the hour of closing, &c., &c. The gates are surrounded a little before ten in the morning by a gathering, deepening crowd, but all friendly and peaceable; and when they open at the stroke of the clock, a dense column pours in through each aperture, each paying his shilling as he passes (no tickets being used and no change given—the holders of season, jurors' and exhibitors' tickets have separate entrances), and all proceeding as smoothly as swiftly. Within half an hour, ten thousand shillings will have thus been taken: within the next hour, ten thousand more; thence the admissions fall off; but the number ranges pretty regularly from Forty to Fifty Thousand per day, making the daily receipts from $10,000 to $12,000. Yesterday was a great Race Day at Ascot, attended by the Queen and Royal Family, as also by most of the habitual idlers, with a multitude beside (and a miserably raw, rainy, chilly day they had of it, with very poor racing), yet I should say that the attendance at the Exhibition was greater than ever before. Certainly not less than fifty thousand shillings, or $12,000, can have been taken. For hours, the Grand Avenue, which is nearly or quite half a mile long and at least thirty feet wide, was so filled with the moving mass that no vacant spaces could be seen from any position commanding an extensive prospect, though small ones were occasionally discoverable while threading the mazes of the throng. The visiters were constantly turning off into one or another department according to their several tastes; but their places were as constantly supplied either by new-comers or by those who, having completed their examinations in one department, were hastening to another, or looking for one especially attractive. Turn into whatever corner you might, there were clusters of deeply interested gazers, intent on making the most of their day and their shilling, while in the quieter nooks from 1 to 3 o'clock might be seen families or parties eating the lunch which, with a prophetic foresight of the miserable quality and exorbitant price of the viands served to you in the spacious Refreshment Saloons, they had wisely brought from home. But these saloons were also crowded from an early to a late hour, as they are almost every day, and I presume the concern which paid a high price for the exclusive privilege of ministering to the physical appetites within the Crystal Palace will make a fortune by it, though the interdiction of Wines and Liquors must prove a serious drawback. It must try the patience of some of the visiters to do without their beer or ale from morning to night; and if you leave the building on any pretext, your shilling is gone. Every actual need of the day is provided for inside, even to the washing of face and hands (price 2d.). But Night falls, and the gigantic hive is deserted and closed, leaving its fairy halls, its infinite wealth, its wondrous achievements, whether of Nature or of Art, to darkness and silence. Of course, a watch is kept, and, under pressing and peculiar circumstances, work has been permitted; but the treasures here collected must be guarded with scrupulous vigilance. If a fire should consume the Crystal Palace, the inevitable loss must exceed One Hundred Millions of Dollars, even supposing that a few of the most precious articles should be snatched from the swift destruction. Ten minutes without wind, or five with it, would suffice to wrap the whole immense magazine in flames, and not a hundredth part of the value of building and contents would remain at the close of another hour.

POPULAR EDUCATION.

The Exhibition is destined to contribute immensely to the Industrial and Practical Education of the British People. The cheap Excursion Trains from the Country have hardly commenced running yet; but it is certain that a large proportion of the mechanics, artisans and apprentices of the manufacturing towns and districts will spend one or two days each in the Palace before it closes. Superficial as such a view of its contents must be, it will have important results. Each artisan will naturally be led to compare the products of his own trade with those in the same line from other Nations, especially the most successful, and will be stimulated to discern and master the point wherein his own and his neighbor's efforts have hitherto comparatively failed. Of a million who come to gaze, only an hundred thousand may come with any clear idea of profiting by the show, and but half of those succeed in carrying back more wisdom than they brought here; yet even those are quite an army; and fifty thousand skilled artisans or sharp-eyed apprentices viewing such an Exposition aright and going home to ponder and dream upon it, cannot fail of working out great triumphs. The British mind is more fertile in improvement than in absolute invention, as is here demonstrated, especially in the department of Machinery; and the simple adaptation of the forces now attained, the principles established, the machines already invented, to all the beneficent uses of which they are capable, would speedily transform the Industrial and Social condition of mankind. I am perfectly satisfied, for example, that Boots and Shoes may be cut out and made up by machinery with less than one-fourth the labor now required—that this would require no absolutely new inventions, but only an adaptation of those already well known. So in other departments of Industry. There is no reason for continuing to sew plain seams on thick cloth by hand, when machinery can do the work even better and twenty times as fast. I shall be disappointed if this Exhibition be not speedily followed by immense advances in Labor-Saving Machinery, especially in this country.But out of the domain of Industry, British Progress in Popular Education is halting and partial. And the chief obstacle is not a want of means, nor even niggardliness; for the Nation is wealthy, sagacious and public-spirited. I think the influential classes generally, or at least very extensively, realize that a well managed system of Common Schools, supported by taxation on Property, would save more in diminishing the burthen of Pauperism than it would cost. I believe the Ministry feel this. And yet Mr. Fox's motion looking to such a system was voted down in the House of Commons by some three to one, the Ministry and their reliable supporters vieing with the Tories in opposing it! So the Nation is thrown back on the wretched shift of Voluntaryism, or Instruction for the poor and ignorant children to be provided, directed and paid for by their poor, ignorant and often vicious parents, with such help and guidance as self-constituted casual associations may see fit to give them. The result is and will be what it ever has been and must be—the virtual denial of Education to a great share of the rising generation.

For this suicidal crime, I hold the Episcopal and Roman Catholic Priesthoods mainly responsible, but especially the former. If they would only stand out of the way, a system of efficient Common Schools for the whole Nation might be speedily established. But they will not permit it. By insisting that no Nationally directed and supported system shall be put in operation which does not recognize and affirm the tenets of their respective creeds, they render the adoption of any such system impossible. They see this; they know it; they mean it. And nothing moves me to indignation quicker than their stereotyped cant of "Godless education," "teaching infidelity," "knowledge worthless or dangerous without Religion," &c. &c. Why, Sirs, it is very true that the People need Religious as well as purely Intellectual culture, but the former has been already provided for. You clergymen of the Established Church have been richly endowed and beneficed expressly for this work—why don't you do it? Why do you stand here darkening and stopping the gateway of secular instruction with a self-condemning assumption that your own duties have been and are criminally neglected, and that therefore others shall likewise remain unperformed? Teach the children as much Religion as you can; very few of you ever lack pupils when you give your hearts to the work; and if they prove less apt or less capable learners because they have been taught reading, writing, grammar, geography and arithmetic in secular schools, it argues some defect in your theology or its teachers. If you really wanted the children taught Religious truth, you would be right glad to have them taught letters and other rudimental lessons elsewhere, so as to be fitted to apprehend and retain your inculcations. It should suffice for the condemnation of all Established Churches ever more, that the State-paid Priesthood of Great Britain is to-day the chief impediment to a system of Common Schools throughout the British Isles.

The Catholic Clergy have more excuse. They, too unite in the impracticable requirement that the dogmas of their Church shall be taught in the schools attended by Catholic children, when they ought to teach them these dogmas out of School-hours, and be content that no antagonist dogmas are taught in the secular Schools. But they receive nothing from the State, and have good reason to regard it as hostile to their faith, therefore to suspect its purposes and watch narrowly its movements. If they would only take care to have a good system of Common School Education established and efficiently sustained in Spain, Portugal, Italy, Mexico, and other Countries wherein they are the conscience-keepers of the great majority and practically omnipotent in the sphere of moral and social effort, I could better excuse their unfortunate attitude here. As it is, the difference between them and their State-paid rivals here seems one of position rather than of principle. And, in spite of either or both, this generation will yet see Common Schools free and universal throughout this realm. But even a year seems long to wait for it.

TOWN GOSSIP.

Preparations are on foot for a grand banquet at Birmingham to the Royal Commissioners, the Foreign Commissioners and the Jurors at the Exhibition, to take place on or about the 16th. This is to be followed by one still more magnificent given by the Mayor and Council of London, which the Queen is expected to attend. The East India Company give one to-morrow evening, but I hope then to be in France, as I intend to leave for Paris to-morrow. The advertisements promise to put us "through in eleven hours" by the quickest and dearest route. Others take twice as many.

Miss Catharine Hayes, a Vocalist of European reputation, who sang the last winter mainly in Rome, means to visit America in September. She is here ranked very high in her profession, and profoundly esteemed and respected in private life. I have heard her but once, having had but two evenings' leisure for public entertainments since I came here. There is but one Jenny Lind, but Miss Hayes need not shrink from a comparison with any other singer. She is very highly commended by the best Musical critics of London. I cannot doubt that America will ratify their judgment.

We have had tolerably fair, pleasant weather for some time until the last two days, when clouds, chilly winds and occasional rain have returned. The "oldest inhabitant" don't remember just such weather at this season—as he probably observed last June. I shall gladly leave it for dryer air and brighter skies.