The article which recently appeared in our columns (page 117) on the above subject has arrested the attention of Joseph Dixon, of Jersey City, N. J., who has sent us a few lines on the subject, in which he states it as his beliefthat the metal in question is the very same as that which he manufactured in 1847-8, and which was held to be pure iron. We were well aware of Mr. Dixon's experiments, and had seen a plate of his metal ; but we cautiously stated in the article referred to that we had not received satisfactory information in relation to the exact nature and composition of the metal; but " if it possessed the advantages claimed for it by its inventor, it was one of the most important inventions of the age." We shall yet be able, we think, to elicit the whole truth in relation to it. Mr. Dixon's pure iron was homogeneous, very strong, quite free from the mechanical imperfections of bar iron ; was easily converted into good steel, and rendered suitable for tools, engraver's plates, and other purposes. If the homogeneous metal of Mr. Howell is the same as that of Mr. Dixon, the latter deserves the credit of the invention, as he was the first person, we believe, who effected the melting of a mass of malleable iron, and the purification of it while liquid. Previous to this a few grains of the malleable iron had been fused in the laboratory, but it was considered impossible to render it available for practical purposes. Why is it that no more of Dixon's homogeneous metal has been manufactured than the few specimens under his own special superintendence ? The British government has ordered several tuns of Howell's metal for the boilers of naval steamers ; and the manufacture of it is said to be established and increasing in Liverpool. Have our people proved so insensible to the advantages of this metal as to allow Uncle Jolm to "take the wind out of their sails"? Specimens of this metal were exhibited at the Fair of the American Institute, and were tested in various ways. A plate of it was found to be double the strength of boiler iron; and yet the invention has been allowed to slumber for the past ten years without good reasons. This is inexcusable. We oove stated that pure iron is more easily oxydized than iron containing silicon and carbon, owing to the great affinity which iron has for oxygen, especially when exposed to moisture. Mr. Dixon informs us that this is true, chemically, but owing to the homogeneous structure of metal made by his process, it is not so subject to destructive corrosion as common wrought iron, because the fibrous construction of the latter, mechanically, presents more favorable points for the action of the oxygen. This is a very good reason indeed, as it is well known, that a piece of bar iron, exposed to the action of salt water, which is very corroding, soon becomes honeycombed. The moisture seems to permeate through the lamina of wrought iron and thereby finds a more extensive surface for oxyd-izing action, than if it were homogeneous. There are some materials which occupy a far more distinguished position than others, as aids to man. The chief among these are fuel in a compact form (such as coal or wood) and iron. Without the former, man might cook his food with dry herbage, like the squalid barbarians on the bleak plains of Asia and South America, but he never could rise to the condition of practising the useful arts. Without iron, man could, indeed, rise to that state in the arts of the ancient Phulicians and Egyptians, in their favorable climates, for they were unacquainted with this metal I but without it, practical mechanics and the manufacturing arts never could have arisen 5 to their present high position, which as far transcends that of those ancient nations as the light of the sun exceeds that of the moon. Without iron. steamships, locomotives, printing presses, power looms, and the hundreds of machines which are the assistants and aids of man in his present civilized state, would be unknown. Unlike fuel, such as coal and wood, however, it is a manufacture itself, and is produced by expensive processes. It is evident, therefore, that any improvement in its manufacture must be of great and general consequence. It is for this reason we so frequently direct attention to everything which comes under our cognizance that has a bearing upon its improvement. If this homogeneous metal is so valuable to the arts, and embraces such important advantages over other kinds of iron, its manufacture in our country should not be delayed for a single month longer. Malcing Breail by Macliinery.—Berdan's Patent Automatic Oven, &c. It is somewhat remarkable that up to the present time, when almost every want of civilized man is supplied by machinery, the manufacture of bread—the first of all necessaries, the "staff of Jife"—should be almost universally carried on in as rude a manner as by the ancients. It is true that the primary process of converting the grain into flour may be said to have arrived at perfection, but beyond this, the manufacture, as generally practiced, differs little from what it was in the days of Moses. The subject has, however, within the last few years, attracted much attention from scientific and ingenious men, both in this country and in Europe, and it now seems that this most imports,nt of all the useful arts is to be no longer behind those which minister to our other wants. A mechanical bakery has just commenced operation in Philadelphia, the ovens and machinery of which are the invention of H. Ber-dan, of New York city, which is capable, when worked up to its full capacity, of converting into bread the enormous quantity of 1,000 barrels of flour daily, estimated sufficient to supply the entire popmation of the Quaker City. By the immense of labor, fuel and space, the bread can be supplied from this establishment to the consumer, at a cost very greatly below that charged by bakers, and even cheaper than it can be made by families, purchasing their flour at retail. A brief description of this immense concern will, doubtless, be interesting to the majority of our readers, though it would require engravings to give anything like an adequate idea of it. The building is four stories high, to the uppermost of which the flour is conveyed in the barrels by a hoisting apparatus, and after being turned out of the barrels, is sifted by suitable machinery, and afterwards conveyed into a large hopper belonging to the kneading machine, which is on the floor below. This machine is composed of a horizontal cylinder, in which rotates a bar for stirring the flour, water and ferment together, a scraper forpre-venting the adhesion of the dough to the cylinder, and a "flopper," which cuts into and opens the dough, takes up several hundred pounds of it at a time, and throws it about in a most remarkable manner, somewhat imitating, on a large scale, the operation of kneading by hand, causing much air to enter into it and be retained within it distributed in small cellules, and making the bread very light, with a small quantity of yeast. From this machine the dough is conveyed to the hopper of the loaf-making machine, the principal portion of which is on the second floor. This machine cuts or molds the dough into loaves, and registers the number made. The molds or cutters of the last-mentioned machine are variable, to enable the loaves to be varied in size exactly in proportion to the market price of flour. The loaves, after being formed, are carried off by an endless apron to a convenient point, to be taken by attendants and placed on brick-bottomed cars, on which they are passed into the ovens and baked. The ovens, of which there are two, are upright, and occupy comparatively little hori- zontal area. They are independent of each other, and each complete in itself, containing a system of upright endless chains, which are constantly in motion, to convey the bread from one door of the oven on the second floor of the building, where the breadis introduced, down to a door on the first floor, where it is discharged when sufficiently baked ; the time occupied in its descent being just sufficient for the baking process, which is made continuous for any length of time, by the introduction of new supplies as fast as the discharges take place, the oven being thus kept constantly filled with the bread at progressive stages of the baking process. While the baking bread is passing down the oven on one side, the cars which have been emptied on the first floor and introduced at another door on the same floor, are passing up through the oven on the opposite side to a door on the second floor, where they are discharged, to be re-loaded and introduced at the first-named door again. There are four doors in all, two on the first, and two on the second floor. The endless chains of the ovens are made with rails, on which the cars run in and out. The doors are opened one at a time, at proper intervals, for the admission and exit of the cars, which are drawn into and expelled from the oven, and moved from the discharging to the receiving doors outside the oven all by machinery ; and the only manual labor in the whole establishment is that of loading and unloading the cars. The oven is built entirely of brick, and the cars on which the bread is baked are, with the exception of light iron frames, made entirely of brick. Of'the advantage of brick ovens it is needless to speak. The ovens are heated by fires which are tended in the basement of the building. This bakery, which is the property of joint-stock company, composed of some of the most influential men in Philadelphia, is one of the most perfect manufacturing establishments we have ever seen ; and its machinery works with the precision of a clock. We had the pleasure of witnessing its operation on the opening-day, which was celebrated -last week by a public djeuner within its walls, at which some of the most distinguished men of the city were present ; and in the speeches that were made on this occasion, Mr. Berdan received some very flattering compliments, to which he replied with great feeling and good taste. The oven and kneading machine have both been patented through the Scientific American Patent Agency is this country, nd' in almost every country where patents are granted. Bakeries on the same principle are now in course of construction in New York, Boston, Baltimore, New Orleans, and other large cities ; and it is hardly venturing too far to predict that similar concerns will be started, and come int.o successful operation, in every city of the Union, for cheap and pure bread is one of the greatest desiderata in large communities. The Tele-stereoscope. The stereoscope is an instrument which, from two pictures taken at different angles, presents to our view objects at a short distance in the solid form. Common pictures have a flat, dead appearance; stereoscopic pictures stand out in life-like relief. The reason ol this is that, with the stereoscope, each of oui eyes obtains a somewhat different view of the object, and they find the true form of it ou of the two perpective views or pictures taken at different points. If, however, the distance from we view the pictures in the stereoscope is considerable, the eyes are too slow in their action to enable the observer to form a correct. idea of the distance and the form of the obj)3ct represented, unless some very favoring ciwumstances oflight and shade assist in doing aoi. Ranges of distant mountains generally appear to the n d eye like perpendicular walls attached to the firmament. In the stereoscope, it is possible to combine two perspective views of a landscape taken from two different points iently distant so as to give the ob- erver a correct idea of the real or true forms smbraced in the views. A stereoscopic pic-ure, therefore, conveys a more perfect repre-lentation of a landscape than an observation made with the naked eye. It is only by ;hanging positions, and thereby obtaining different perspective views of a landscape, and Dy comparing these views, that an observer is enabled to perfect his observations, and to obtain something like a correct idea of the forms of the objects embracing the scene. If the observer could take different views of a landscape at the same moment, the scene presented to his vision would be charming and ife-like. But this he cannot do, neither can t be done with the common stereoscope for distant objects ; but in Dingier's Polytechnic Journal, published at Augsburg, Germany, it is stated that this is accomplished by a simple instrument called the "tele-stereoscope," recently invented by M. Helmholz. It consists simply of a smooth board, four feet long, on each end of which a looking glass is fastened perpendicular to its plane, and making an angle of 45, with a line drawn longitudinally through the center of the board. In the middle of the board, two other smaller looking-glasses are fastened parallel to the first two, and so close together as to enable the observer to look at once with an eye into each. If it is desirable to magnify the object, an opera glass or spectacle lens may be inserted between the eye and the looking-glasses. By these means the right eye sees the landscape as it appears in the looking-glass at the right end of the board, while the left eye sees it as it appears on the looking-glass at the left end. The distance of the observer's eyes is increased by these means from about three inches (the common distance) to four feet, and he thereby obtains a view which as far surpasses stereoscopic photographs as an oil painting excels an engraving. The journal referred to also states that objects distant from one to two miles appear correct in the back ground, and nearer objects very perfect, particularly trees, the limbs and branches of which are distinctly separated, and the whole landscape stands out solid and beautiful. Gomez & Mills' Safety Fuse. Last week, at the New York State Arsenal, we were present during a series of experiments with the above fuse. It is a peculiar chemical composition, enclosed in a paper case and wrapped round with cotton, and for land service it is passed through tar to render it impervious to rain and the dampness of the ground, but for submarine purposes it is coated with gutta percha. It is of flat form, and in consequence not so liable to injury as the ordinary round miner's fuse. The fire passes through this fuse at the rate of one mile in four seconds ; and one of the experiments consisted in firing two guns, the one with a length of about fifteen feet of fuse, and the other with about two hundred feet, both lighted at once, and from our position on the steps of tho arsenal, each seemed to go off at the same moment. The fuse is inserted in the cartridge, and passes through the mouth of the gun to the hand of the gunner, so that an enemy spiking a gun does not render it any more unfit for service than it was before. One man can fire a battery of any number of ns at almost the same instant with this fuse, and it is without doubt a great and valuable addition towards that perfection of the art of war which shall ensure universal peace. This invention was recently tried with success at W-shington, under the personal direction ofthe Secretary of War. Water in the Sea. If we uld obtain any idea of the water which the sea contains, let us suppose a common and general depth for the ocean ; by computing it at only two hundred fathoms, or the tenth part of a mile, we shall see that there is sufficient water to cover the whole globe to the height of 503 feet ; and if we were to reduce this to one mass, we should find that it would form a globe of more than sixty thousand miles in diameter. Earth and Ocean Temperatures* As we descend into the interior of the earth the temperature gradually increases. In mines, and during the sinking of artesian wells, it has been constantly observed that, at a certain distance from the surface, a point is attained at which the heat of summer anl the cold of winter produce no effect upon the temperature; and beyond this point the heat augments in a regular ratio of 1 Fah. for every 55! feet of descent. It is true that this increase of heat is not uniform in every part of the earth, as it differs in different strata at the same depth from the surface, but this variation is so small as not to affect the general rule. Reasoning from this data, geologists naturally conclude that at the depth of say 200,000 feet, the temperature must be 3,600—a heat which must keep all the materials in the center of the earth in a state of fusion. It is, therefore, taught by many, that the center of the earth is a fiery mass, and that the globe's solid crust does not amount to more than a fiftieth part of its diameter. But if this is a law or rule regarding the solid parts of the earth, the contrary seems to be the case with the fluid portions of it. Lieut. Berryman, U. S. N., in his deep sea soundings, seems to have eliminated a totally opposite law reigning in the ocean, viz., that the cold increases according to the depth; and in connection with this other remarkable phenomena. He says :— "Five hundred miles north of Bermuda we found the greatest reliable depth ever obtained, it being over four miles; and accompanying this were thermometrical observations of a singular character, indicating phenomena never before discovered or conceived, and which at this moment are an unsolved problem to the scientific world. In a long series of experiments the temperature was indicated as existing ten, fifteen, and twenty degrees below the freezing point. This may be owing to the defective instruments ; but if so, a consistency of error was preserved almost beyond tlie possibility of chance." The records of these deep sea soundings go to contradict the well-known and established law that water freezes at 32 Fah. ; also that there is one law relating to temperatures for the ocean and another for the dry land. There must have been some defect in the instruments referred to, which indicated an ocean temperature below the freezing-point, or else the stratum of fluid reached at the great depth mentioned was not common salt water, but some other fluid, incapable of freezing, except at a much lower temperature. We do not believe, however, that any such fluid exists where these deep sea soundings were taken. T ie Vine Disease. This disease, which has ruined the crops of the vine-growing countries of Europe, is at last conquered. Mr. Kyle, a Scotch gardener, has discovered that the application of sulphur to the plant is an effectual preventive and remedy. Of such importance had this disease become to France, that the Society for the Encouragement of Agriculture offered a prize of $2,000 for a cure, and many smaller ones for researches on the subject. This first prize has been divided between Messrs. Kyle (who was also awarded the $100 gold medal of the Society), Duchartre, Gouties, and Maris. M. Barral, in his report to the Council, makes the following remark :—" It was England who inoculated the vine disease into Europe, but it is remarkable that it was in that country that it was most perfectly studied by Mr. Berkeley,-and again in the llame country that a cure was discovered by Mr. Eyle." In this country, and especially those parts of it where the vine is cultivated, it ought to be recollected that it should be studied as well as nurtured, and that, like every other plant, the more care and attention that is paid to its growth, the more abundant and luscious will be its fruits. It is not enough that our soil is so rich that it will grow luxuriantly without much oare. We yet ought to pay atten-' tion to it to produce still more luxuriance. Ijieiit* Maury in the Navy* "Lieut. Maury, who has been physically incapacitated for naval service by a broken leg, having been' restored to rank by the Naval Courts, other officers now demand that he either be sent to sea, or got out of the way of their promotion by resignation." We copy the above paragraph from an exchange, and we hope, for the honor of the country, that the last statement is not true. Lieut. Maury is an ornament to his country, and we rejoice that he has been restored to rank by the Naval Courts, and that he will neither resign nor get out of the way, to make room, perchance, for some lazy, worthless fellow, who might disgrace the American navy. Lieut. Maury has done more to promote nautical science than any man now living, and hence we urge that he should be retained just so long as he lives. If he is incapacitated to do physical service because of a lame leg, his head is not broken, and by the aid of its workings he can do quite as much as can those who would supplant him, by the combined power of their legs and all their other qualifications. Nelson, when he achieved his greatest victory, was blind of an eye, and had only one arm. The Stubborn " Leviathan." The talk and the writing about the launching of this vessel have now become leviathanlike in dimensions. We wait with patience for the period when we can say, "like leviathan afloat, lay her bulwarks on the brine." By the latest news from Europe, five attempts at launching had already been made and failed, and further operations are suspended for a long time to come, on account of the breakage of chains and hydraulic pumps employed to move her. No less than three hydraulic rams, one powerful windlass, and the double chains which drag the vessel towards the river have all been burst or broken. She still sticks on her ways, at two-thirds the distance from where she was built. The London Times states it will cost $500,000 to launch her ; the London Engineer says it has cost $350,000 already, and as it has to be moved twice the distance it has already traversed, it may cost more than $1,000,000. Just think of one million of dollars being expended upon launching this monster ! What in the name of common sense possessed its builders to construct her at such a distance from the water ? Circle of the Scientific Press* France, with her accustomed energy in the cause of science, has made another great step forward, by the forming of a new society under the above title, and which is to consist of members of her scientific press, who, at their meetings, will discuss the inventions and discoveries of" the past month, in every branch of science and art, and lay before the world the results of their discoveries. At their first meeting in Paris, on the 16th of November last, they were presented with a full account of the submarine tunnel to connect England and France, by the designer, M. Thom6 de Gamond, and after an animated discussion it obtained their approval. Many inventions were then exhibited, such as a watch which will give the correct hour at any meridian, a way-measurer for vehicles, and many articles of vertu, and interest. We look with great hope to the future of this society, comprising, as it does, among its members, the chiefs and subordinates of a scientific literature which is the most purely scientific, although not perhaps, the most practical, existing in any country in the world. The Black Hills* There are some sections of our extensive country almost as little known as the interior of Africa. The St. Louis (Mo.) Republican states that a party has just recently returned to that city from an exploring expedition in a wild region known by the above appellation. It is a vast country of movable sands, sterile, bleak and inhospitable. There are small streams at remote distances in it, upon which there is spare vegetation ; sufficient, however, for the subsistence of the Indians' horses and some buffalo. It must ever be the home of nomadic tribes, who wander about like those of the wild wastes of Asia in search of the small patches of pasturage which are fructified by the irrigation of distant rivulets. This country has been supposed to be fertile from its geographical position and its appearance upon the map, but it proves to be wholly otherwise. The party consisted of sixty men, and the Sioux, who are numerous there, forbid the return of any more white men. They said that this party might pass, because it was the first, but no others must come, as they scared away their game, and would discover their strongholds and hiding-places. Quack Names for Burning Fluids. A correspondent writing to us from Fall River, Conn., states that a burning fluid called "Helion Oil," has recently come into extensive use in that city, a)1d he asks if it is one of those fluids liable to explosions, which we described lately in an article in our columns. We have had other inquiries of a similar character relating to a fluid called "Excelsior Oil." Not having seen the oils which have received such names, we cannot tell what they are, but we suppose they are coal oils with flashy names to astonish the marines. All such fluids should receive their true name in connection with that of the manufacturers, such as "Breckenridge Coal Oil, " "Newark (Ohio) Coal Oil," &c. The quality of the oil will thus become an advertisement to the manufacturers, and incite them to make improvements, in order to excel one another in producing the best and cheapest article. Vocal Macliiuery of Bjrtls* It is difficult to account for so small a creature as a bird making a tone as loud as some animal a thousand times its size ; but a recent discovery has shown that, in birds, the lungs have several openings communicating with corresponding air bags or cells, which fill the whole cavity of the body from the neck downward, and into which the air passes and re-passes in the progress of breathing. This is not all. The very bones are hollow, from which air pipes are conveyed to the most solid parts of the body, even into the quills and featEei's. The air being rarified by the heat of their body, adds to their levity. By forcing the air out of the body, they can dart down from the greatest hights with astonishinjj velocity. No doubt the same machinery forms the basis of their vocal powers, and at once resolves the mystery into a natural ordering of parts.—Gardner's Music of Nature. Preserving Railroad Timbers MESSRS. EDITOES—1 would suggest a cheap plan for increasing the durability of railroad ties and other timbers in exposed situations. Make a cheap long tank, with a furnace under it, and place it on a railroad car. Fill it with coal tar, (which can be obtained at any of the gas works for $1 50 a barrel,) and bring it to a boiling heat. Now introduce a set of ties or timbers, and boil them for a short period, raising them up and down, by some simple contrivance, four or five times, when undergoing the operation ; then take them out, and allow them to dry for a few days. It will require but a short time to prepare timbers in this manner, and the cost is not worth naming, in comparison with the durability imparted to them over those laid down in their natural condition. One set of tar-prepared ties will last three times longer than an unprepared set. Fence-posts should also have their ends which enter the ground treated in this manner. J. SCOTTON. Newark, Ohio, January, 1858. [Our correspondent is perfectly right in his conclusions respecting the advantages to be derived from this mode of treating railroad timbers. The only objection to the process is the handling of dirty sticky timbers ; but that is of no consequence while plenty of persons can be found ready to do the work.— Ens. Preparing Liquid Glue. MESSRS. EDITORS—The following 13 a method by which I have prepared liquid glue, and have found it very convenient :— Take the glue in any quantity desired, and dissolve it in as small a portion of boiling water as possible ; it will then be found too thick for use. While it is still hot, take the glue-pot from the fire, and reduce or thin the glue to the proper consistency with alcohol ; then put it in a bottle, the mouth of which must be covered with india rubber or other material impervious to the air. Liquid glue made in this manner, and placed in bottles, may be kept ready for use for a number of years. I have some glue which I now use that was thus prepared six years ago, and is as good as when newly made. ItoOnly requires to be slightly warmed for application during cold weather. MERCHANT KELLY. Bentonville, Ind., Dec., 1857. [This is a very good method of making glue for use where only a little is required, and that but at considerable intervals of time. Liquid glue is very liable to rapid putrefaction in warm weather, and it freezes in cold weather. Alcohol preserves it from both of these influences. A bottle of liquid glue is very convenient for use in families to mend broken chairs and other pieces of furniture. Cure for Chapped Hnmls. MESSES. EDITORS—I have seen in a late number of the SCIENTIFIC AMERICAN directions for curing chapped hands. I have used the following for many years, and have recommended it to a number of friends, and wherever it has been used, the result has been all that could be desired :— Take two ounces of glycerine, and one ounce of rosewater, mix, and rub your hands well with it before retiring to rest. It is pleasant, agreeable, and cleanly, and its effects are truly wonderful; indeed, whatever business a party may be engaged in, it will not fail to effect a cure. The glycerine alone is equally as good, but the rosewater is more pleasant to use. WILLIAM NASH. Bmnford, Conn., January, 1858. Destruction of M0!1ols. Periodically—at the end of every six months Or so—it becomes imperatively necessary that we should destroy or otherwise dispose of such models as have been sent to our office for examination, have been declared by us to be not patentable, have then remained uncalled for by their inventors, and have consequently accumulated in our possession. As the commencement of a new year is a period of general cleaning-out and brushing-up in every well-ordered establishment, and constitutes one of the above-mentioned epochs of destruction in our own, we hereby notify all inventors wishing to preserve those of their models which have now lain long in our hands, that they must order them away immediately. The best of the models of unpatentable devices are retained by us, discretionarily, even if they have been in our possession as long as six months ; but we do not keep such as have been so poorly constructed as to be not worth the expense of carriage homeward to their owners, and we do not hold ourselves accountable for any model which has been stored in our office longer than six months. The above remarks equally apply to all models which have been sent to us for the purpose of having engravings prepared from them. Of course, it is almost unnecessary to add that we most carefully preserve all such models as we have received with positive instructions to make applications for patents thereon, and that such are forwarded to the Patent Office at Washington at the earliest opportunity. Finally, we again admonish all who wish to save models which have been long lying in our office, that they must quickly them to be boxed up and shipped to their respective owners ; or otherwise, by and by, the latter will wish to have their models when restitution will be an impossibility.