THE ERA STEAMER" AND ZANDER'S EXPANSION AND CONDENSING SYSTEMS. The favourite passage boat between London and Richmond during the past season has been the Era Steamer; but of those who have travelled by her, perhaps not one in a thousand has cared to inquire how the excellent performances, for which she is remarkable, have been accomplished, or indeed ever imagined that there is anything in or about her different from other steam vessels, beyond, perhaps, a little more skill and attention in management. A visit to the engine room of this vessel will, however, soon satisfy any intelligent inquirer who is moderately conversant with the steam-engine, that there is not only much in the construction of her machinery which is new, but that there are advantages resulting from this novelty, far beyond any which a mere above-deck survey would suggest. The engine is on Woolf's plan, that is, with two cylinders, one smaller than the other, in the proportion of 3 to 1, and the steam, of course, is worked expansively; but certain additions have been made to Woolf's arrangement, by which the gain from expansion is carried to a much greater extent than it has ever been before. According to Mr. Zander, the inventor of these additions, the Era performs by his improved means of expansion three times the duty of an engine worked in the common way without expansion; or, in other words, is worked at a saving to the owner of two-thirds of the ordinary expenditure for fuel; and from the data and calculations which we shall presently lay before our readers, there is every reason to believe, that this is by no means an exaggerated statement of the gain realized. Nor is this all; for though the steam is usually worked at about 40 lbs. pressure, while most of the other vessels which ply above bridge are worked at 7 lbs. and 10 lbs., the same additions to the machinery, by which the great economy in fuel is effected, are of such a nature as to obviate all danger on the score of excess of pressure. The additions to which we refer form part of a series of improvements for which Mr. Zander took out a patent more than three years ago, (June 17, 1839;) and the real history of the Era we understand to be, that, though plying as an ordinary passage-boat between London and Richmond, she was fitted out for the more immediate and express purpose of testing, on a practical scale of sufficient magnitude, the efficiency of Mr. Zander's system of expansion and other improvements before bringing them more prominently under the notice of the public. The Era was in constant daily work during the whole of the season of 1841, as well as that which has just terminated; so that the results we have now to speak of are not those of any holiday trial, or a dozen such trials, but the result of more than a twelvemonth's continual working, under almost every possible variety of seasons and circumstances. The description given by Mr. Zander, (who is a native of Sweden,) of his system of expansion, in his Specification, has the defects to be expected at the hands of a person describing, in a language not his own, things which it is least of all easy to describe in any other than one's vernacular tongue; but it is so distinct and clear, nevertheless, that we prefer giving it as we find it, to any version of our own. We have great pleasure in adding, that, should any of our readers desire to refer from our pages to Mr. Zander himself, they will meet with a degree of sincerity, modesty, and singlemindedness, which are not always, or indeed often the accompaniments of inventive genius and scientific acquire ments. "I will suppose," says Mr. Zander, referring to a drawing, of which fig. 1, on our front page is a copy, "that K is a steam boiler of a capacity to contain nine cubic feet of steam put into a boiling state." "A is the furnace; b the water line in the boiler; C is an open box filled with five cubic feet water, and fixed to the upper part of the boiler in such a manner that the steam from the boiler surrounds the water on all sides, or the sides of the box. It will be plain that the water in the box C is by the steam in the boiler heated to the same temperature which it itself possesses, after which it goes out in the atmosphere through the pipe d. When now the cock e is closed, the steam increases in power (or pressure,) but in an inconsiderable degree, because the water always in equal proportion, with the increase of the temperature of the water in the box C. Suppose now that the safety ventilator, (safety valve ?) f, to be loaded, with, for instance, five pounds on every square inch of its sectional area. When the steam in the boiler, and the water in the box C, has arrived at a temperature of two hundred and twenty-six degrees Fahrenheit, the ventilator begins to rise, and the steam to escape. I have found that it required one hundred and fourteen cubic feet of steam from the water in the boiler, to give the water in the box C the same temperature and pressure; but when this box is removed it requires only three cubic feet of steam from the water in the boiler, in order to produce five pounds of overpressure, or two hundred and twenty-six degrees Fahrenheit temperature. I have consequently reservoired 22 times more of steam in the water of the box C; but if the cock e is now opened, it is evident that the steam in the boiler K escapes into the atmosphere. The water in the box C has, in the first instance, two hundred and twenty-six degrees temperature, and its steam five pounds of pressure above the atmosphere; it therefore evaporates, and the steam escapes through the pipe d, until it has got a temperature of two hundred and twelve degrees Fahrenheit, and equal pressure with the atmosphere, or the steam in the boiler, it must evaporate nearly the one hundred and fourteen cubic feet of steam received. The only inconvenience which now presents itself in carrying this into execution, is, that the heat of the steam requires a certain time to pass into the water layer in the box C, and also at a decreased pressure to be enabled to evaporate therefrom, and much heat escapes unused from the sides of the box; but this obstacle is perfectly removed by dividing instead of the single box C, the same into several parts, and by retaining the same water surface in each part. If I then have divided this water, in, for instance, ten parts, it follows that the heat of the steam from the boiler will pass into the mass of water nearly ten times quicker, and at a decreased pressure in the chamber, and will evaporate nearly ten times faster, or approximating thereto. In the construction of the steam reservoir, it is therefore advisable that it should be divided into as many small parts as possible, in order to give as large a surface as may be possible. "For marine and other steam-engines, I have considered the form of the water chamber to be the most suitable, as is shown in figures 2 and 3, front page:-a, a,are narrow guides or channels about a quarter of an inch high, and from a quarter to a half, or greater inch wide, made of copper or other metal. These guides lay transversely below another layer of similarly made metal guides b, until a series of guides shall have been formed as high as it is intended to have the reservoir. Should it be required to have a reservoir of a large size, the length of the guides may be divided into several partitions, and in order that the water in them may not during a high swell or sea, go out from one partition to another, partitions made of plates may be placed between them, and a smaller partition may also from the same reason be made in each guide by pressing up its bottom in different places. The guides are attached to each other in one system by brass, or other wire in any convenient manner; the guide system is then placed in a room or chamber above the boiler, about three inches from the top plate. The good effects of the preceding arrangement are next detailed. "The very superior advantage to be gained by the use of this method invented by me, and here above described for reserving the water steam, must therefore be evident, both as regards the lessening the capacity of the boiler and the quantity of water which is thereby gained, as of offering a greater security against explosion when a sudden generation of steam takes place. But the greatest advantage to be derived from the use of this apparatus is, that the steam may be made use of dilated to an extent above what hitherto it has been possible to effect with advantage, because, owing to the difficulty of an over collection of steam in the common steam chamber, there has been a great obstacle in the use of expansive steam-engines, whose preference before others is now fully established. In order to carry into effect the above purpose, I make use of a cylinder, wherein I intend to introduce from a boiler, with steam reservoir apparatus, high-pressure steam, from four, or higher atmospheric pressure. Suppose, for instance, four atmospheres of steam, at one-fourth of the length of the stroke, the steam will be cut off, and afterwards, with its dilation, act to the end of the stroke, where it has one atmosphere of pressure, and now to be conducted into a steam reservoir, in which there is a system of guides which contain heated water, filled in by a cock on the top-plates, on a convenient mode, or pumped from the bottom. The steam is then inclosed in the water of the steam reservoir, and is conveyed thence by means of opening the escape ventilator into another low-pressure cylinder, exactly similar, as to quantity and quality, as if it had been generated in a boiler, with only a loss of about one-fourth of a pound to one pound of pressure. But I consider it as a great loss not to suffer the same steam to dilate at least four times, also, in the lowpressure cylinder, before it escapes into the condenser, from which I likewise obtain a gain. I can by the method now described, with advantage, suffer the steam to dilate at least sixteen times of its primitive capacities. The steam reservoir, which receives the steam that comes from the high-pressure cylinder, may be placed in any position most suitable; but in steam-vessels it may, in most cases, be convenient to place the same above the boiler, from whence a pipe conveys the steam to the low-pressure cylinder. The beforedescribed steam reservoiring system may be used with advantage in all kinds of boilers or steam chambers, in order to regulate the steam; 1 therefore reserve to myself the right of making use of the same, in whatever kind of boilers or steam chamber, whether high or low pressure, as thereby I obtain, first, a steadier steam; second, greater security against explosion; third, the practicability of thereby using smaller boilers and a less quantity of water; and fourth, and chiefly, that by use of them one great dilatation of the steam is possible." In the Era, the steam regenerator is not as recommended in the preceding extract, and shown in fig. I, placed above the boiler, but between the two cylinders of the engine; an arrangement rendered expedient in this case, probably, by the small height of the engine-room. The boiler is a tubular one, but with a peculiar arrangement of the tubes, for which Mr. Spiller, the maker of both the engine and boiler, had a patent some years ago. The steam, it must be observed, is not allowed to pass unrestrictedly from the regenerator to the low-pressure cylinder; for provision is made that before the communication is opened between them, the steam in the former, shall have attained a pressure of at least one pound above the atmosphere. Mr. Zander gives two plans for this purpose in his specification, which are represented in figs. 4 and 5 of the engravings on our front page; the one shown in fig. 5, is that adopted on board the Era. The following is Mr. Zander's description : "Fig. 4 a is a cylindrical vessel closed at the top, and the lower end plunged in mercury, contained in a circular groove or cavity formed between two concentric cylinders b. These cylinders are supported upon the top plate of the reservoir N, and communicates with them by the opening c. The cylinder a is loaded by the weight d, according to about one pound and a half for each square inch of the top area of the cylinder. E is an admission valve; the stem f of this valve is attached to the rod g, which is attached to the top of the cylinder a. When the steam pressure rises in the reservoir N to one and a half pound above the atmosphere, the cylinder a will rise, and open the admission valve E; but when the steam rises higher, the load d on the cylinder strikes against the frame h attached to the cylinder b, and the admission valve E is kept open for induction steam to the low pressure cylinder. "c in fig. 4, is exactly of same construction as fig. 5, but from the cylinder top a, fig. 3, is a rod b attached, which, by a lateral connecting rod, rests on a valve fixed in the bottom of a cylinder d into the reservoir and boiler. This cylinder connects, by a bent pipe, the reservoir with the boiler. The weight f, on the top of cylinder a, is so regulated, or the diameter of the cylinder a compared with the diameter of the valve, that when the steam in the reservoir is under three quarters of a pound (according to pleasure) pressure above the atmosphere, the weight f will, by the rods connected with it rest on the valve, and keep that open until the steam from the boiler passes through the valve into the reservoir, keeps the steam there over three quarters of a pound pressure; then the cylinder a will rise to the frame g, and keep the valve closed. Before the engine is set going, a little cock, on the reservoir N, is opened; then the air in the reservoir escapes through it, and it is held open until the water in the reservoir is heated to a proper degree of the steam from the valve." We have still some further improvements to notice, which Mr. Zander has made in the condenser, or refrigerator. Fig. 6 is a side elevation, and fig. 7 a front elevation of that in use in the Era. "The refrigerator stands in a vessel filled with water or other cooling medium, and the eduction steam from a working cylin |