into the mouths of the people. Hear them talk in their own plain and expressive way, of subjects which you are used to see treated only in the language of books, and ridicule is the last idea which will arise in your mind. Knowledge, evidently, digested and fairly applied, commands respect in all stations; and whether it appears among our labouring brethren in the shape of history, mathematics, or political economy,in all shapes, at all times, it is welcome! May all manifestations of it encourage those to whose exertions it is in any measure to be attributed, to new and greater labours in so high and holy a cause! These are hardly the beginning; the end-who shall imagine?

2, Holles-street, Clare Market.

W. REES.

TREVELYAN'S PRINTING PRESS. [From the Report of the Cornwall Polytechnic Society.]

d

The framing of this press was of the ordinary construction. The improvement consisted in the arrangement of its levers,

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for giving and regulating the pressure. These levers are contained in the hollow of the piston, and are shown in the above figure: a, b, c, are the principal levers. That marked a, is jointed to the head of the press, the lower part of c, is jointed to the back of the platin, and b is placed between them, and works in sockets on their opposite ends. The crooked arm, d, is merely intended to change the direction of the force, and to increase the leverage; any power applied at its lower end causes the lever, b, to turn towards a vertical position, and at the same time, brings the others nearer to the same line. This, of course, forces the platin down on the type, with a pressure which increases rapidly as it descends, a quality which renders this arrangement very efficient for printing purposes, particularly as it admits of the nicest adjustment of power requisite for the different kinds of work.

HOUSE-MOVING IN AMERICA.

House-moving is curious, but it does not appear that much is gained by the process. A flooring of beams is introduced below the foundation of the house, and rests on three or more beams; these beams resting on others, on which they are slid along, impelled by powerful screw-jacks, and by greasing the surfaces of the beams that come in contact.

"In consequence of the great value of labour, the Americans adopt, with a view to economy, many mechanical expedients, which, in the eyes of British engineers, seem very extraordinary.

"Perhaps the most curious of these is the operation of moving houses, which is often practised in New York. Most of the old streets in that town are very narrow and tortuous; and, in the course of improving them, many of the old houses were found to interfere with the new lines of street; but instead of taking down and rebuilding those tenements, the ingenious inhabitants have recourse to the more simple method of moving the whole, en masse, to a new site. This was, at first, only attempted with houses formed of wooden frame-work, but now the same liberty is taken with those built of brick. I saw the operation put in practice on a brick house, at No. 130, Chathamstreet, New York, and was so much interested in the success of this hazardous process, that I delayed my departure from New York for three days, in order to see it completed. The house measured 50 feet in depth, by 25 feet in breadth of front, and consisted of four stories, two above the ground floor, and a garret story at the top

"The operation is attended with very great risk, and much caution is necessary to prevent accidents. Its success depends chiefly upon getting a solid and unyielding base for supporting the screw-jacks, and for the prolongation of the beam to the new site which the house is to occupy. It is further of the utmost importance that, in working the screws, their motion should be simultaneous, which, in a range of 40 or 50 screwjacks, is not very easily attained. The operation of drifting the holes through the walls also requires caution, as well as that of removing the intermediate pieces between those of the beams, which pass through both walls. The space between the beams is only 2 feet, and the place of the materials removed is, if necessary, supplied, while the house is in the act of moving, by a block of wood which rests on the beams. The screwjacks. by which the motion is produced, require also to be worked with the greatest caution, as the cracking of the walls would be the inevitable consequence of their advancing unequally.

Notwithstanding the great difficulty attending the successful performance of this operation, it is practised in New York without creating the least alarm in the inhabitants of the houses, who, in some cases, do not even remove their furniture while the

process is going forward. The lower part

of the house which I saw moved was occupied as a carver and gilder's shop; and, on Mr. Brown, under whose directions the operation was proceeding, conducted me to the upper story, that he might convince me that there were no rents in the walls or ceilings of the rooms, I was astonished to find one of them filled with picture frames and plates of mirror glass, which had never been removed from the house. The value of the mirror glass, according to Mr. Brown, was not less than 1500 dollars, which is equal to about 3007. sterling; and so much confidence did the owner of the house place in the success and safety of the operation, that he did not take the trouble of removing his fragile property. I understood from Mr. Brown, that the whole operarion of removing this house, from the time of its commencement till its completion, would occupy

about five weeks; but the time employed in actually moving the house 14 feet, was seven hours. The sum for which he had contracted to complete the operation was 1000 dollars, which is equal to about 2007. sterling Mr. Brown mentioned, that he and his father, who was the first person who attempted to perform the operation, had followed the business of house-movers' for fourteen years, and had removed upwards of 100 houses, without any accident, many of which, as in the case of the one I saw, were made entirely of brick. I also visited a church in 'Sixth' Street, capable, I should think, of holding from 600 to 1000 persons, with galleries and a spire, which was moved 1100 feet; but this building was composed entirely of wood, which rendered the operation much less hazardous.-Stevenson's Engineering of America.

ROAD-MAKING IN AMERICA.

The roots of the felled trees are often not removed; and in marshes, where the ground is wet and soft, the trees themselves are cut in lengths of about 10 or 12 feet, and laid close to each other across the road, to prevent vehicles from sinking; forming what is called in America a "Corduroy road," over which the coach advances by a series of leaps and starts, particularly trying to those accustomed to the comforts of European travelling.

Some interesting experiments have lately been set on foot at New York, for the purpose of obtaining a permanent and durable City road, for streets over which there is a great thoroughfare. The place chosen for the trial was the Broadway, in which the traffic is constant and extensive.

The specimen of road-making first put to the test was a species of causewaying or pitching; but the materials employed are round water-worn stones, of small size; and their only recommendation for such a work appears to be their great abundance in the neighbourhood of the town. The most of the streets in New York, and, indeed, in all the American towns, are paved with stones of this description; but owing to their small size and round form, they easily yield to the pressure of carriages passing over them, and produce the large ruts and holes for which American thoroughfares are famed. To form a smooth and durable pavement, the pitching-stones should have a considerable depth, and their opposite sides ought to be as nearly parallel as possible, or in other words, the stones should have very little taper. The footpaths, in most of the towns, are paved with bricks set on edge, and bedded in sand,

similar to the "clinkers," or small, hardburned bricks, so generally used for roadmaking in Holland.

The second specimen was formed with broken stones; but the materials, owing chiefly, no doubt, to the high rate of wages, are not broken sufficiently small to entitle it to the name of a "Macadamised road." It is, however, a wonderful improvement on the ordinary pitched pavement of the country; and the only objections to its general introduction, as already noticed, are the prejudicial effects produced on it by the very intense frost with which the country is visited, and the expense of keeping it in re. pair.

The third specimen is rather of an original description. It consists of a species of tessellated pavement, formed of hexagonal billets of pine wood, measuring 6 inches on each side, and 12 inches in depth. From the manner in which the timber is arranged, the pressure falls on it parallel to the direction in which its fibres lie; so that the tendency to wear is very small. The blocks are coated with pitch or tar, and are set in sand, forming a smooth surface for carriages, which pass easily and noiselessly over it. There can be no doubt of the suitableness of wood for forming a roadway; and such an improvement is certainly much wanted in all American towns, and in none of them more than in New York. Some, however, have expressed a fear that great difficulty would be experienced in keeping pavements constructed in this manner in a clean state, and that, during damp weather, a vapour might arise from the timber, which, if it were brought into general use, would prove hurtful to the salubrity of large towns.

In the northern parts of Germany, and also in Russia, wooden pavements are a good deal used. My friend, Dr. D. B. Reid, informs me that at St. Petersburg, a wooden causeway has been tried with considerablə success. The billets of wood are hexagonal, and are arranged in the manner of the American pavement. At first, they were simply embedded in the ground; but a great improvement has been introduced, by placing them on a flooring of planks laid horizontally, so as to prevent them from sinking unequally. This has not, so far as I know, been done in America.-Stevenson's Engineering of America.

AMERICAN STEAM-BOILER EXPLOSIONS.AN ACT FOR INSTITUTING EXPERIMENTS UPON SAFETY APPARATUS.

An Act authorising the appointment of persons to test the usefulness of invention to improve and render safe the boilers of steam-engines against explosions.

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Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled, That the President of the United States be, and he hereby is, authorised to appoint three persons, one of whom at least shall be a man of experience and practical knowledge in the construction and use of the steam-engine, and the others, by reason of their attainments and science, shall be competent judges of the usefulness of any invention designed to detect the causes of explosion in the boilers; which said persons shall jointly examine any inventions made for the purpose of detecting the cause and preventing the explosion of boilers, that shall be presented for their consideration; and if any one or more of such inventions or discoveries justify, in their judgment, the experiment, and the inventor desires that his invention shall be subjected to the test, then the said persons may proceed and order such preparations to be made, and such experiments to be tried as in their judgments may be necessary to determine the character and usefulness of any such invention.

Sec. 2. The said Board shall give notice of the time and place of their meeting to examine such inventions, and shall direct the preparations to be tried, at such place as they shall deem most suitable and convenient for the purpose; and shall make full report of their doings to Congress at their next session.

Sec.3. To carry into effect the foregoing objects, there be, and hereby is,appropriated out of any money in the Treasury not otherwise appropriated, the sum of six thousand dollars; and so much thereof as shall be necessary for the above purposes shall be subject to the order of the said board, and to defray such expenses as shall be incurred by their direction, including three hundred dollars to each, for his personal services and expenses: Provided however, And their accounts shall be settled at the Treasury, in the same manner as those of other public agents.

THE CANAL LIFTS ON THE GRAND WESTERN CANAL BY JAMES GREEN, M. INST. C. E. [From the Proceedings of the Inst. of Civ. Eng.]

The lift which is the subject of the following paper was erected by Mr. Green in the year 1835, on the Grand Western Canal, and has been in operation ever since. Lifts are not intended to supersede the use of canals in all cases, but in those in which a considerable ascent is to be overcome in a short distance, and in which the water is inade

quate to the consumption of a common lock, or in which the funds are inadequate to the execution of the work on a scale adapted to such locks.

This lift is 46 feet in height, and consists of two chambers, similar to those of a common lock, with a pier of masonry between them; each chamber being of sufficient dimensions to admit of a wooded cradle, in which the boat to ascend or descend floats. The cradle being on a level with the pond of the canal, a water-tight gate, at the end of the cradle, and of the pond of the canal, is raised up, and leaves the communication betwixt the water in the canal and in the cradle free, and the boat swims into or out of the cradle.

The cradles are balanced over three castiron wheels of 16 feet in diameter, to the centre of one of which is fitted spur and bevil gear, so that the motion may be given by machinery worked by the hand, without any preponderating weight of water in the cradle, when scarcity of water renders this necessary. To this hand gear in also attached brake-wheels and a brake-lever for regulating the motion.

It is obvious that the weights of the additional length of the suspending chains on the side of the cradle which is the lowest, must be counterbalanced; for this purpose there is attached, to the under-side of each cradle, a chain of equal weight per foot with the suspending chain, and this elongates under the ascending, and is shortened under the descending cradle; thus the disparity in the weights due to the suspending chain is obviated.

It is so arranged that the water in the upper cradle is about two inches below the level of the water in the pond; the consequence of which is, that the upper cradle has a slight preponderance first, sufficient to set the machinery in motion; the weight of this water is generally about one ton; it may however be regulated at pleasure.

The strength of materials is the great desideratum in machinery of this nature, and though the lift here described is but 46 feet, and the boats about eight tons, the same method is applicable to much greater heights and larger tonnage. The advantages of these lifts over common locks are, great economy of construction, and a great saving of time and water.

The time occupied in passing one boat up and another down this lift of 46 feet is three minutes, whereas thirty minutes would be required to attain the rise of 46 feet by locks; thus the saving in time amounts to 9-10ths for boats of eight tons.

The quantity of water consumed is about two tons for eight tons of cargo, whereas in common locks it is about three tons of wa

ter per ton of cargo; the saving is, therefore, 22 parts out of 24, or very nearly 92 per cent. If the trade were all downward, there would, by the use of the lifts, be carried from the lowest to the highest level of the canal, a quantity of water equal to the loads passed down.

Mr. Green stated that in some parts of the canal it had been found impracticable to get a sufficient drain to empty the chamber-they were compelled, therefore, to use a half-lock of eighteen inches fall; that there were seven lifts and one inclined plane on the canal,effecting a rise of 262 feet in eleven miles. That he should not recommend them as applicable to boats of more than 20 or 30 tons. The width of larger boats was an obstacle. They were extremely advantageous for narrow canals; for boats of 50 or 60 feet in length, and about 30 tons.

Mr. Parkes remarked, that he considered the question of narrow canals as a most important one-the advantages to be derived from narrow canals was a subject to which sufficient attention had not been paid.

The President called attention to the remark in Mr. Green's paper respecting the quantity of water carried up from one level to another in a downward trade wherever these lifts are used; then a coal country on a high level may supply itself with as much water as it sends down coal. The subject of inclined planes being alluded to, especially those of the Morristown Canal of 200 feet each, where a rise of 1600 feet is effected by eight inclined planes, Mr. G. remarked, that more water and time must be expended, the friction and length being much greater. In the lifts there was only as much water consumed as was equal to the load, but that he should not consider them as practically applicable to more that 60 or 70 feet. Favourable levels with ascents of more than 60 or 70 feet could seldom be found; could he have had the choice of the line in this particular instance, he should have effected by four lifts the rise for which seven are now employed.

RENDEL'S FLOATING BRIDGE ACROSS THE HAMOAZE FROM DEVONPORT TO TORPOINT.

[From the Minutes of Proceedings of the Institution of Civil Engineers.]

The floating bridge now described is used as a system of communication betwixt the opposite shores of the Tamer, a little to the north of Devonport. The width of the river at this site is 2550 feet, at high water, and its greatest depth at spring tides 96 feet. The ordinary velocity of the stream is 34 knots an hour, but under heavy land floods, it is increased to 5 knots. The line of pas