This boiler was described and illustrated on page 97 vol . XX, of the SCIENTIFIC AMERICAN. At that time we had no even,of the power of the boil. Generate steam economically an opinion based upon the structure of the boiler, and the testimony of others whose opinions are valuable and trust worthy such matters, and whose names we gave in full. Since that time we have had the opportunity to observe and test critically a stationary boiler constructed on this plan, now in operation at Paterson, N. J., and also to inspect a marine boiler made on the same principle now in operation at the General Office of the New York and Erie Railroad Company, in this city. We find that the stationary boiler will evaporate 10'65 lbs., of water at 212” into perfectly dry steam for every pound of anthracite coal consumed. The experiment by which this result was determined was performed in the most approved manner—that adopted in the- U. S. Navy experiments. We are, therefore, now able to' speak from actual knowledge of the merits of this boiler, and it “is with pleasure that we re-open our columns to discuss an improvement calculated to produce a large saving in the consump- tiorl:of fuel used for steam generation. The sources of loss in steam generation may be included in two general classes; namely, imperfect combustion, and radiation. The reader will understand that we make a wide difference between steam produced in a boiler and steam consumption in an engine, and that the sources of loss in the latter are not to bo considered, in estimating the power value of a boiler, since good results cannot be expected from the best boiler connected with a defective engine ,, ll{lr from the best engine supplied with steam from a defective boiler. A boiler must therefore; stand alone in any estimate of its worth; its evaporative power, ('mparesJ” with the coal confirmed, and its comparative safety, being the principal points which challenge inquiry. Its evaporative power will depend, of course, upon the extent to which the causes of loss above classed are eliminated, while its comparative safety may be in-, ferred from the nature of the materials used in its construction, the character of the workmanship, and the removal of those faults of construction known to impair the safety of boilers in general. The skilled constructor will make safety the primary consideration, and economy the second That the reader may comprehend the successive steps by which the present form of the Gerner boiler has been reached, he is referred to Figs. 1 and 2 of the accompanying engravings. The inventor of the Gerner boiler, starting with the assumption that, so far as safety alone is regarded, no form of boiler is, COMMON CYLINDRICAL BOILER. ft T 3:E COMMON CYLINDRICAL BOILER WITH THE GERNER REraFORCEMNE A^ACTED. 'Pftj. G ^^ THE GERNER STATIONARY BOILER. superior to the old-fashioned cylinder, has proceeded step by step to develop its steam-producing power without relinquishing its known elements of safety. The Figs. referred to give, respectively, an end and side view of a plain cylinder boiler, set in brickwork, W L being the water line, and from X to X, around the lower section of the boiler, showing the extent of heating surface. Figs. 3 and 4 give two views of the same boiler, with its J)ower and economy greatly increased by the application to it of the Gerner Reinforcement, an application that may be made to any plain cylinder or flue boiler. The Gerner Reinforcement consists Yil placing -within a cylindrical boiler another cylinder of j Ust suffi ciently smaller size to leave a space (when set a little -out ®f center) of about four inches at. the bottom and ends, ..croatiino- gradually to about six inches JS the top. This cylinder, by displacing- the large mass of water as shown in Fig. 2, reduces it to a thin sheet, which fills the space bet:veen th'a two cylinders, and Entirely surrounds the inner one; the water line being now noal the top instead of the middle of the boiler. Tho inner cylinder 1S ®mply supported at each end by a bracket attached to the oute'r beaten and is provided with a dome, open at the top, setting within the dome of the outside cylmder. The steam, as it is generated, rises, as shown by the arrows in Fig. 4, into the outer dome and thence passes by the :nner don:e or conducting pipe, int° the interior of the innCT ^Und^ which thus becomes a large steam reservoir entirely fined with dry steam, which is kept in its normal condition by the jacket of hot water which surrounds and [protects it from radiation, the temperature which protects being the same that produced it. The supply pipe, E, conveys the steam as it is required, from the.center of the steam reservoir, r, thus acting as a steam trap to convey on1y dry steam, were not the essentials to that condition already complied with. It wm be observed that the pressure of the steam within the reservoir equalizes that of the steam in the water outside , thus obviating the necessity for “ staying “ and the use of heavy iron II its construction. The water being carried so high i n the boiler admits of the brickwork being set off from it, and the fire' thus carried entirely around it, throughout its entire length and ends, thereby doubling the extent of heating surface. The brick-work may be thrown in an arch over the' boiler or the successive layers of brick “stepped in” like a rever- beratory furnace, as shown in Fig.3. It is obvious that among the advantages gained by the Gerner Reinforcement are, first, doubling' the heating surface ; and, second, the thin sheet of water presented to the action of heat instead of a large mass, by which steam is not only generated much more rapid- © 1869 SCIENTIFIC AMERICAN, INC. [OCTOBER 2, 1869. 210 iy and economically, but the lessened volume of water materially increases the safety of the boiler. If authority for this statement be asked, we refer the reader to Williams able work on Heat and Steam page 171, where he asserts that the risk of explosion is greatly increased by the increase of water in the boiler, every cubic foot of which, beyond what is absolutely necessary for the generation of steam, being an additional source of danger." A steam reservoir of great capacity is supplied where the steam is constantly protected from all extraneous influences, and its perfect dryness assured. Figs. 5 and 6 are a cross-sectional end view and a vertical longitudinal section of the Gerner stationary boiler. The shell consists of a cone-shaped cylinder, so called, its smaller end being over the grate. The boiler's axis is set level. The flame envelopes the boiler, and its escape is checked at the top and sides by a brick partition at the rear, and its exit is through a vent underneath the larger end of the boiler into the flue and chimney. Within the. shell is placed a similar cylinder of less dimensions, leaving a water space of about four inches at the bottom, increasing to, say, six inches at the top. This water space surrounds the entire inner cylinder. The steam dome, C, receives the steam, passing it through the pipe, D, into the inner cylinder (steam reservoir), B, whence the steam finds exit to the engine through the pipe, E. It will be seen by the foregoing description that all of the advantages described in the reinforcement have been maintained in the Gerner stationary boiler proper, and its efficiency and economy still further augmented by its conical shape. The angle of the heating surface, as here presented to the action of the fire, is best calculated to catch and absorb the heat, impingement beiug more direct and effective, whilethe free circulation of the water from the position in which the conical shells retain it, is greatly promoted. It will also be observed how scientifically this form provides an extensive combustion chamber, wherein the gases of combustion may become thoroughly ignited and the radiation from the fire strike very directly upon all sides of the cone, while the rapidly narrowing passage towards the escape flue, in both the vertical and horizontal direction, so progressively retards the gases in their passage to the outlet that their combustion is perfected and their heat, as far as possible, imparted to the boiler. There is no lodgment for refuse, ashes, and dirt, of any kind, about the boiler, and all sediment within is naturally deposited at its lowest point. T, whence it is easily blown off. The advantage derived from sotting the boiler without contact with the brick work is great, for when, as is necessary with ordinary boilers, the brick-work and boiler are brought in contact, any water from the top will settle at the point of contact, become decomposed, and very quickly weaken the boiler by oxidizing the iron. The “ Society for the prevention of Boiler Explosions, “ in England, report that fifty per cent of the explosions of stationary boilers are clearly traceable to' this cause. Unequal expansion and contraction are also, doubtless, as much promoted in a boiler but half bricked in, as in a tubular or locomotive boiler with its varying diameters and position of shell and tubes ; for the upper half, exposed to the atmosphere, while the lower part is subject to intense heat, must be unequally afiecteJ, and soon lead to the rapid destruction of the boiler. We have given above the results of a test on a stationary boiler of the Gerner construction, 10 feet long, 2 feet front, and 3 teet rear diameter, with a grate surface of 4J404lJ- square feet, whiah show that the boiler is producing 500 lbs. of dry steam par hour for every 50 lbs. of coal consumed, after setting aside thE) fraction 0'65 of a lb. over 10 lbs of steam produced by the consumption of a pound of anthracite. This margin of 6'5 per cent of the total production, will cover manj of the defects of unskillful firing. Assuming, then, that II practice the boiler will evaporate 500 lbs. of water per hour with a consumption of 50 lbs. of coal, and allowing 33 lbs. of water to be the fair standard of a horse power, this boiler is capable of supplying 15-horse powers. But it may be asked, how is this gain to be theoretically accounted for? As further answer to this inquiry, already partially met in this article, we may be permitted to make the following extracts from accepted authorities on steam : ” The present construction of the multitubular boiler, as it is called, may be truly stated as a disgrace to the science of this age of progress."—Page 29 “Modern Practice of Boiler .Engineering,” by Robert Armstrong. Revised by John Bourne. ” Heat, communicated by flame, must depend on its mass,” -Page 132 “Treatise on Combustionof Goat,” by C. Wye Williams. ” The tubular system is chemically, mechanically, and practically a destroyer of ignition and the sustained existence of flame."—Ibid, page 134. ” The resultof the adoption of the multitubular system has been a less perfect combustion, a larger development of opaque smoke, a greater waste of fuel and heat, and a more dangerous application of it."—Ibid, page 122. "Any expedient which supersedes the present flue, and multitubular marine boiler, will very considerably accelerate the passage between this country (England) and America.— Page 29 “ Modern Practice of Boiler Engineering,” by Robert Armstrong. Revised by John Bourne. It will thus be seen that practice and theory do not conflict, and that the results obtained by the Gerner boiler exactly coincide with what might be expected on purely theoretical considerations. Its structure is such as complies with the principles laid down by the eminent authorities quoted and comprehends them all. The Gerner principle, as herein described for stationary boilers, is even more effectually applied to portable and marine boilers. We have already said that a marine boiler (i.e., built upon the same plan as one intended for a steam vessel), is now in successful operation at the New York and Erie Railroad General Offices (Grand Opera House), corner of Eighth avenue and Twenty-third street, New York. It is 16 feet long, 6i- feet in diameter, and has produced, according to the testimony of"J. W. Brooks. Superintendent of'Machinery and Motive Power_ N. Y. and E. R. R, the—so far as we are aware—unparalleled result of 110-horse powers, 3,30^pis. water evaporated per hour, with an economical result of over 12 lbs. of water to 1 lb., of coal, and at our visit to this establishment we were convinced of the very superior dryness of the steam produced. We append a comparative statement of dimensions and economical results, a 40-horse power boiler taken as an example : Number ILengthDiameterEconomical result. STYLE OF BOILERS.ofininPounds of water boilers.feet,inches.to 1 of coal. Locomotive boiler123428 Return tubular boiler......116437 140456 Plain cylinder boiler240865 Gerner Stationary boiler.12236x4810 ” Portable boiler...1136611 The question of horse power is a very important one to purchasers. The only true test of a boiler is the amount of water it will evaporate per hour into perfectly dry steam. Taking the average of steam engines, as now constructed, it may be fairly stated that the conversion of from 30 to 35 lbs. of water per hour into dry steam, under a pressure of 50 lbs., is a liberal standard for a hors'1 power. The Gerner boilers are built upon that standard, and are guaranteed to produce that result. The business management of this boiler is now controlled by Kasson&Co. , 119 Broadway, New York (P. O. Box 5,195), from whom full descriptive circulars and price list may be obtained on application.