An ironmaster of Wolverhampton, England, writes to the Ironmonger of improvements now in operation in the Cleveland district, as follows : " On entering the Cleveland ironmaking district any one from Staffordshire must be strucJi with surprise that not a flame is to be seen coming from any of the furnaces, except at intervals for a few moments. This is consequent on tht4r way of utilizing the tunnel head gases. They close the throats of their furnaces by means of two castings, a cap and a cone. The cap, which is rested on the brick work of the furnace, has no bottom, but the opening is filled by a cone held in its place by machinery so arranged that when the cap is charged it can be lowered, and so permit the materials so charged to escape into the furnace. The Cleveland ironmasters, most of them, think that a better distribution of materials is insured by this mode of filling, and that it is an easy and inexpensive way of collecting the tunnel head gases. We, however, in Staffordshire, who use the gases, do not agree in thinking a close top at all desirable or attended with a saving of expense in the long run. In the first place, it actually prevents the furnace from being filled by some feet, in order to lower the cone, and also it is impossible to know, without going on to the farnaC3 top and feeling with a rod through a hole made for the purpose how far the furnace is from being full, and as Eothing tends to regulate the quantity of iron made more than keeping a furnace filled to one exact hight, this is an objection. The gases, where the top is closed, are usually blown by force of engine, not only through the materials in the furnace, but into and out of the gas pipes, of whatever length, size, or shape may happen" to be the firing furnaces, flue, and indeed the chimney tops. The back pressure caused by this is very objectionable. We prefer to exert, by means of a good chimney, such an amount of suction beyond all firing places as to draw the gases, or their products of combustion, from the furnace into the mains, and on through firing places and flues by its very suction, thus rather encouraging the furnace to drive, instead of by back pressure tending to hinder the driving. Another advantage of the open over the close top is that the gas being drawn off is ncluded to mix with the air necessary lor combus:ion, whereas in the other case it comes off at a pressure, and consequently is not so inclined. From being at a pressure it is liable to leakages, and may accumulate, so causing explosions, whereas, wherever it is drawn through a leak, it will, by the same power, be carried on into the chimney, and so rendered harmless. I am pleased to be' able to state that one Yorkshire firm work our open-topped system and, in spite of all they hear from Cleveland ironmasters'and managers as to the superiority of closed tops, after years of experience in working open ones, having just raised one of their furnaces very considerably, they have again applied our open top system, which they informed me works admirably. INCREASED HIGIIT OP FURNACES. " The point, however, in which nearly all the Yorkshire furnaces, especially the most improved, differ most widely from ours is in their great hight, also in width of bosh. Six years back furnaces were built in Yorkshire very much as they were in Staffordshire, and at that time their yield of fuel varied from thirty to thirty-six cwt. of coke per tun of iron made. At the present time the hights of furnaces vary from seventy-five to one hundred and five feet, while boshes are of all dimensions, from sixteen to thirty feet. Their yields of coke, too, have varied with the increased hight of furnace and diameter of bosh to an average varying from twenty-eight cwt. down to sixteen cwt., if not lower. These increases to both hight of furnace and width of bosh have taken place so simultaneously, and the temperature f blast has also been so increased during the same time, that it is very difficult to decide to which of the improvements the better yield of coke is chiefly due. I should have felt very doubt-ful on this point myself, had it not been that Mr. Horton, of Lilleshall, has raised his four cold blast furnaces at the Lodge twenty feet without increasing their size of bosh, and thereby saves seven cwt. of coke to the tun of iron. This hight of furnaces I consider to be the most important question for Staffordshire. Are we using, say five cwt. to the tun more coal than we need, if only our furnaces were raised a few feet ; in other words, where about thirty-five cwt. of coal are used might we do with thirty ? If so, at a make of 150 tuns of iron per week, and charging the coal as worth 8s. per tun delivered into the furnace, the saving would amount to 780 per year per furnace. If we could get rid of coal or coke, tho quality of resulting iron must be improved, as coal or coke is the great sulphur carrier. There are over-careful ones who are not inclined to look favorably, or even hopefully, on any improvement that is likely to necessitate a change in their plant, as it now stands ; and others, from opinions formed, I consider errroneously, say, " But our coal or coke is too weak, and would be crushed by the increase of hight of column ot measures charged." I answer, it has not proved to be so in I Shropshire, nor is the cold blast prevented from entering the furnace, though blown at the same pressure and in the same way as before; namely, about 31 lbs. pressure through the leather bags and open muzzles, usual in cold blast furnaces, into the cold blast furnaces, muzzles not even jointed into tweers. I firmly believe that our furnaces, and coal, or coke, will bear increased hight, provided they are not made much wider. Indeed, I consider that increase of hight does not to any very great extent increase crushing weight, as the materials rest at the bottom on the bosh, which causes those above to carry themselves to a very great extent against the sides. It is well-known that if you fill a tube with very fine materials the downward pressure is not anything like equal on the bottom or any other part of 147 them to what would be due to the hight of an unsupported column. This is a thing that ought to be settled by positive experiment, as to every coal in the district, on one experimental furnace. We shall certainly work coals that are not now considered worth trying, just as years back no one would consent to work new mine, or as they then called it, stinking coal, in a furnace. I know, though it was before my time, an instance in which 500 or 1,000 tuns of first-rate new mine coal were ofi'ered to be given if it was worked in the furnaces, so as to prove it a furnace coal. It now works to fully as good a yield as thick coal. high temperature of blast. " Ironmasters in Cleveland, and some other districts also, now use blast of the very highest temperature they can raise, and consider that every increase of heat saves a further very considerable portion of the coal necessary for smelting, besides improving the quality of iron by removing coal, the chief supplier of sulphur. As this heat is raised by the com-Imstion of tunnel head gas, of course it is done at a very trifling cost. My cautious friend, however, will again say ' Yes, but what is the wear and tear on stoves/ particularly when I tell him that in one or two instances I have heard it said it does not do to trust to pyrometers ; the best way is to make sure of your blast pipes being red hot. There are, however, several ways of avoiding such fearful wear ; namely, by having such a large internal area of stove pipes at work per furnace as shall pass the blast SiOwly enough to cause it to be heated to the same temperature as the pipes it is passing through. Iron pipes may be safely kept at a dull red heat, as witness a plumber's iron. A better way still is to us Cow par's or Whitwell's fire brick stoves. Where it is wanted ' to keep the blast at such a temperature as shall easily smelt i lead or zinc, one of the best ways of proving its temperature ' is to drill a half or three quarter hole nearly through the cast iron of muzzle pipes and put a bit of zinc or lead to boil; in trying, pass a bit of wire through the metal to see if it is in a i liquid state. clothing blast pipes. \ " Another thing of which the Cleveland ironmasters are I very careful, and which we have proved the very great value of, is to clothe eveiy bit of hot blast pipe very carefully with some good non-conductor. The cheapest and best plan of doing this is to take one part of salt, one of whitening, and two of pufi* of cinder (to make puff of cinder, fill a molder's hand ladle with liquid cinder, and then empty the cinder into cold water ; it must be crushed afterwards). To the above four parts, add a good quantity of cow hair and mix up with water to a proper consistency for plastering. For first coat make it so liquid that it can be put on with the whitewash brush, and afterwards lay it on with a trowel as roughly as possible, not more than half an inch thick at a time. After three coats wrap it with iron wire, and you can continue this to any thickness you like. calcining kilns. "Another most valuable improvement which they invariably use is that of close-running calcining kilns for burning the ironstone. This is doubly valuable to us in Staffordshire, on account of the cost of our ironstone as compared with theirs. Ironstone raw costs them from 3s. to 5s. 6d. per tun, delivered into their kilns ; while the expense of ours is from 17s. to 18s.; kilns also save largely in fuel and labor, one tun of very, fine slack being enough to calcine twenty-two ot stone, while one man and an engine boy can calcine all the stone required to make 400 tuns per week. The Yorkshire mode of running the cinders on to the top of wagons is also attended with a large saving of labor. No doubt there are other things which escaped my eyes, but these are quite enough to show the rapid strides the northern masters have made and how important it is we should adopt all useful improvements." The Science Association. The American Association for the Advancement of Science convened at Salem on August 18th. A large number of the most prominent American scientists, as well as a considerable number of lesser lights, were present. We are unable to give extended space in this issue to the proceedings of this learned body. The first session was opened by an interesting address from Henry Wheatland, of Salem, Chairman of the Local Committee. After a response from the Mayor a short business meeting was held. Professor F. W. Putnam was appointed to act as permanent Secretary in the absence of Prof. Lovering. The Secretary read a list of eighty new members, who were unanimously elected. Prof. Agassiz invited the members to visit the Museum of Comparative Zoology at Cambridge. Owing to the excessively limited capacity of the museum, in comparison with the size of the collections, they would have to come in small bodies, but he would do the best he could for them. Prof. Pierce intimated that the astronomers had some revelations to make on the subject of the recent eclipse. The President replied that a general session would be held some evening in the ensuing week for the purpose of hearing them. The general meeting was then adjourned until ten o'clock to-morrow. The organization of the sections A and B was then effected by the choice of the following officers : Section A, of Mathematics and Physics—Chairman, Prof. Silliman; Secretary, Prof. Henry Wurtz, of New York; Standing Committee, Prof. Barker, of New Haven j Prof. Murray, of New Brunswick, N. J.; Prof. Rogers, of Alfred Center, N. Y. Section B, of the Natural Sciences—Chairman, Prof. Agassiz ; Secretary, Prof. T. Sterry Hunt; Standing Committee, Profs. 0. C. March, A. C. Hamlin, and E. D. Cope. After the election of these officers, the sections adjourned In the afternoon the Association was prfeisent by invitation at the dedication of the Peabody Academy of Science. The exercises consisted in the formal transfer of the East India Marine Society's Hall and Museum to the Peabody Academy, and five set addresses at the Tabernacle Church. The ceremonies were of necessity somewhat complex and protracted. First, Mr. William C. Endicott, President of the Academy, opened with an account of Mr. Peabody's gift, and the object and aims of the Peabody Academy. Then the Hon. J. H. Clifford, of New Bedford, spoke on the part of Mr. Peabody. His Honor, Mayor Cogswell, spoke for the town of Salem. M. B. H. Silsbee, President of the East India Marine Society, gave a sketch of the history oi that notable institution, which was, and is the object of the just pride of Salem. Mr. Wheatland spoke for the Essex Institute, younger but scarcely less renowned than the Marine Society itself. Finally, Col. Foster had to speak for the scientific men, pilgrims, as it were, at the shrine of Salem and Peabody. The Marine Society dates back to 1799. Membership was restricted from the first to those who had doubled the Cape, either as supercargo, factor, or commander of a vessel. In those days the East India commerce of Salem was the pride of America. In the number of its ships and the value of its trade Salem was far ahead of either Boston or New York. The objects of the Society were to assist by its funds the widows and orphans of deceased members, to improve the art of navigation, and to form a free museum for the instruction and delight of Salem. In all these undertakings the East India Society was singularly Successful. Dr. Nathaniel Bowditch, while filling an office in connection with this Society, prepared that dictionary and bible of sea captains known as Bowditch's Practical Navigator, a work which has remained for moid than a generation without a rival. The museum treasures up the essence of a thousand voyages, is rich in the romance of the sea and of the past, and has besides a scientific value which can hardly be overestimated. As the commerce of Salem declined, the race of circumnavigators began to die out. Of 348 members of the once-proud Marine Society, only 70 survive Just at the right moment Mr. George Peabody, by a munificent gift, placed the treasures of the Museum in security from all future auctioneers, and gave them even new claims to respect by uniting them with the cabinets of the Essex Institute. It was this union which was cemented and celebrated to-day. The East India Society have parted with their building and collections to the Peabody Academy, which certainly starts with as much capital, both mental and material, as any similar institution in the country. We will in a future issue notice the subsequent proceedings of the Association. Heating Cars ly Steam. Practical experiments on a large scale have been made in Germany on this BUtr|ect especially by the Brunswick Government R. R., the Prussian Eastern R. R,, the Hanoverian Government R. R., and the Lower Silesian R. R. On the Brunswick R. R. the steam was taken from the boiler of the locomotive, passing through a small cock of 1 in. interior diameter, into a large pipe of copper about 20 in. in diameter. Two such copper pipes were laid lengthwise below the floor of each passenger car, and connected by hose with the pipes of the adjacent cars. The pipes were covered by a grate along the walking floor. Under the seats they were covered by a wide box of sheet iron, open in front, so as to let the heat into the compartment and to protect the seats from the immediate radiation. These arrangements effected an increase of temperature in the cars of about 25 Fah., which is quite a favorable result. On the Prussian Eastern R. R. the heating by steam of the passenger and baggage cars of the express trains was introduced in January, 1865. The steam is produced by a small tubular boiler standing in a compartment of the baggage car, and is carried along the train through a 1 in. pipe fixed to the lower part of the wagons. The maximum steam pressure is 30 lbs. The pipes are joined by caoutchouc hose between the wagons. The heating )f the compartments is effected by hollow cylinders connectec below with the above described main pipe. The admission of the steam into the cylinders is regulated by cocks or valves from the outside of the wagons. It has not been found coivenient to have this regulation done by the passengers fron the inside of the compartments, and all the arrangements jut in at first for this purpose had to be removed. The temperature in the wagons can easily be increased 50 Fah. The steam pressure is \ery nearly the same over three wagon lengths, and consequently the heating power of the cylinders is about equal ii the first three wagons. The above arrangements would herefore be sufficient for a larger number. No objections oi difficulties of any importance have been met with in using this system. The trains are running regularly over a distame of several hundred miles. The consumption of coal is aboit 1 lb. per English mile, thus causing but a very small expuse. The Hanoverian Governnent R. R. runs daily two mail trains, with steam heating, between Cologne and Berlin. The steam is generated in a anall tubular boiler put up in a compartment of the bagga car. The heating pipes are laid through the cars lengthwise, their axes being about at the level of the floor. The wsgons of one train contain four parallel pipes of wrought iron those of the other train contain but two pipes of sheet iroi. Both kinds of pipes have a diameter of 2| in. They are ituated at a hight of but one inch between the passenger sejts, and located there immediately below the floor, so that a hin sheet of iron with which they are covered is even with tie floor level. The emanation of the heat takes place principaly below the seats, where the pipes are uncovered. This emjnation ean be lessened and regulated by valves so arranged as to cover the pipes more or less. The valves can be worked from the outside of the cars by the employes, as well as from the inside by the passengers. On the first trial of these heating arrangements the temperature of the air was raised from 41 to about 60 Fah. The consumption of coal amounted to 25 lb. per hour, during which time 175 lbs. of water were used. The whole arrangement has been found good and convenient. Further experience will show if it will prove sufficiently effective in severe frost. The steam heating machinery actually in course of construction on the Lower Silesian railroad, is similar in principle to that of the Hanoverian railroad. The details are not yet known.— Van Iostrand's Magazine. Hartford Steam Boiler Inspection and Insurance Company. The following report of inspections for the month of July is made by this company : During the month 337 visits of inspection have been made, 552 boilers examined—471 externally and 202 internally—and 45 tested by hydraulic pressure. The number of defects discovered 173, of which number 28 were especially dangerous. These defects were as follows: Furnaces out of shape, 16—1 dangerous ; fractures in all, 118—3dangerous ; burned plates, 26—1 dangerous ; blistered plates, 34—1 dangerous; cases of incrustation and scale, 43—4 dangerous ; cases of external corrosion, 35—3 dangerous ; cases of internal grooving, 8 ; water gages out of order, 7 ; blow-out apparatus out of order, 5—3 dangerous ; boilers without blow-out apparatus, 5 ; safety valves overloaded, 12—3 dangerous; safety valves inoperative, 3—all dangerous ; pressure gages out of order, 40—4 dangerous ; boilers without gages, 2 ; boilers with broken stays, 2 ; cases of deficiency of water, 2—both dangerous. In one of the cases reported, the fracture was so great and the water escaping so freely, that it was with difficulty the water in the boiler could be kept at the proper level, with the pump constantly running. In the case of blistered plate, reported dangerous, after the blister had been trimmed off the plate was left so thin that the inspector's hammer easily went through it. Of the cases of scale in boilers, several were found to be from one fourth to one half an inch in thickness. In the dangerous cases of corrosion, the plates were found so badly eaten into that the inspector's hammer penetrated them. i Of the three dangerous cases of inoperative safety valves, two were reported by the inspector as having the loads placed at proper points, but it was found that, in addition to these the " trap doors " in the floor above were bearing on th(3 top of the weights. In the other case the inspector found a heavy timber resting on the lever, which had fallen ther(3 quite unknown to the engineer. The importance of trying the hight of water in boilers before firing up should be thoroughly impressed upon watchmen. It was forcibly illustrated at one ol our agencies during the month, as following: An appointment was made to inspect a new cylinder boiler used in a stove foundery, at 0 a.m. When the inspector reached the boiler room he found a brisk fire under the boiler, which had but about two inches of water in it. Happily the watchman had left the furnace doors open, so that the boiler was not red hot. Upon inquiry it was found that the proprietor had blown off the boiler the previous evening, but had forgotten to notify the watchman not to fire up as usual. The man-hole plate had been left in the boiler, and the watchman, seeing no indications to ths contrary, supposed all was right. Comparison of tlie Covering Powers of Wliite Paints. The following is a test now adopted by many dealers for testing the covering powers of white pigments: " Fine, bufF Manilla wrapping-paper, stretched on frames of wood, is painted with best coach black, and varnished until the surface presents a glassy smoothness. To cover and conceal this shining black surface, and present a white surface, is the object of the test; the utmost care being taken all through to note the exact number of grains, by weight, of material used in each and every coat. No turpentine is used in the paint* ing, the paints being thinned with linseed oil to a proper consistency for spreading evenly under the brush. The first coat is applied to the whole surface of the paper ; the second to a fraction more than three fourths of the sheet, a portion being left in every case, whereby to compare the effects produced by the successive coats. " It will be understood that a separate sheet is used for each brand. Size about two and one eighth square feet." Blackberry Wine.—Measure your berries and bruise them ; to every gallon add one quart of boiling water; let the mixture stand 24 hours, stirring occasionally; then strain off the liquor into a cask ; to every gallon add two pounds of sugar ; cork tight, and let it stand until the following October, and you will have wine ready for use without further labor, that every family will highly appreciate and never do without afterward if they can help it. Farmers and Mechanics' Institute, Easton, Pa.—The Eleventh Annual Fair of this Association will be held at Easton, Pa., commencing Tuesday, Sept. 14, 1869, and ending Friday the 17th. A large number of premiums are offered. Entries should be made before 5 o'clock on the 13th. The entry books will be opened on Monday, Sept. 6th, at the office of tho Secretary, James M. Porter, Esq., in Easton whc* may be addressed by parties interested. 148 Improved liOcomotive for tlie Pacific Hailroad. Our engraving is an example of the Leggotype process, a photographic method of reproducing engravings of ail kinds, the invention of W. A. Leggo, of Montreal, Canada. The process is now extensively practiced at Montreal by Leggo & Co., where they have a large establishment. We have examined many excellent specimens of their reproductions. The double locomotive, of which we here give an illustration, was designed by Robert F. Fairlie, and constructed for the Central Pacific Railroad by Messrs. William Mason & Co., of Taunton, Mass. Of this engine, which is intended to be employed on the Sierra Nevada inclines on the western side of the summit, we herewith publish a side elevation. The engine is carried on six pairs of 3 feet Oin. wheels, disposed in two groups as shown, each group being driven by a pair of 15-in. cylinders with 24-in. stroke. The tractive power will thus amount to 257*14 lbs. for each pound of effective pressure per square inch on the pistons, or with a mean effective cylinder pressure of 100 lbs. per square inch, the engine will exert a pull of 25,714 lbs., or very nearly 11 tuns. The weight of the engine in working order is 54 tuns, or about 4J tun wheel, and as the whole of this weight is avail- able for adhesion, we have no doubt that the great tractive power of the engine will be fully utilized. The engine has about 1,650 feet of tube surface, 125 feet of fire-box surface, and a fire-grate area of about 25 square feet, so that it will no doubt have ample steaming power. The water is carried in a pair of wing tanks, holding collectively 3,000 gallons; and coal bunkers are provided capable of carrying 2i tuns of coal. Altogether, we believe that the engine of which we have aoove given particulars will be found well designed for the work it will be called upon to perform, and we anticipate that it will prove to be the forerunner of a number of locomotives of a similar type. Mr. Fairlie's system of locomotive construction is pre-eminently adapted for use on such a line as the Pacific Railroad, and indeed for American lines generally, and from the favor with which his plans are already being regarded by some of the leading railroad engineers in the United States, we believe that the practical results obtained with the engine we illustrate will be watched with great interest. Velocity oi Projectiles. At the conclusion of the President's address, delivered before the Institution of Mechanical Engineers, at Newcastle, England, on the evening of August 3d, Captain Noble's apparatus for determining the velocity of projectiles in various parts of the bore of a gun was exhibited in the library of the Literary and Philosophical Society. The instrument was explained and various experiments were conducted by Captain Noble, in the presence of most of the auditory who had been present at the delivery of the address. The object of the instrument, which was called a chrono-scope, was stated to be the measurement of very minute portions of time, and it had been specially constructed with reference to artillery purposes. In describing the means that had been adopted for obtaining and retaining a uniform motion, Capt. Noble pointed out that the instrument consisted of half a dozen disks placed on an axle, these disks being put in motion by means of a heavy weight, and their relative velocity being regulated by a train of toothed wheels. A uniform and very rapid rotation was thus imparted to the disks ; each of which bore a certain ratio to the one preceding it. Knowing the speed of one, therefore, they would readily calculate the rate of revolution of the most rapidly revolvijig disk; and by a special clofek-work arrangement the precise speed, to hundredths of a second, could be indicated at any moment. Supposing the first toothed wheel to describe five revolutions within a second, the last of the series would revolve 750 times—the same space of time—such was the ratio of one disk to the other. The weight was so arranged that any required speed could be obtained. The speed was generally—taking the velocity at the circumference—from 1,000 to 1,200 inches per second. If it were exactly 1,000 inches per second, an inch of rotation at the circumference of the wheel would represent the thousandth part of a second ; and so by an arrangment attached to the instrument, they were able to read to the thousandth part of a second; the time actually capable of being measured, so far as the rotation of the wheel was concerned, was the millionth part of a second. From experiments recently made at Woolwich to determine the speed, it was found that 750 revolutions were made in 24'4 seconds, second and third experiments giving 24*2 and 23*9 seconds respectively. Another series of experiments gave the 750 revolutions in 23'4, 23*5, and 23*4 seconds, and on a third occasion 23'3, 23*4, and 23*5 seconds. The instrument was, therefore, almost absolutely accurate. Capt. Noble next showed the mode of registration, which was effected by means of an induction coil. In measuring the velocity of a projectile, the primary wire of the coil was attached to any point of the barrel of the gun, or a set of wires mght be so attached at intervals along the barrel, and at theinstant of the passing of the shot, the wire or wires would bt cut by the projectile, and an impression would be left upon the disk, which was covered with prepared paper for receiving the spark. Each of the disks might be attached to some portion of the gun barrel by a separate coil, and the precise moiient of time at which the shot passed the identical spot woild be most accurately recorded upon the disk. An experinent was performed very successfully with the view of mor( clearly showing how exactly and perfectly the apparatus performed its object; the gun being fired, the six sparks wers instantly perceptible, and the velocity of the projectile, thrmgh as many portions of the bore, was indicated. Capt. Ncble then showed how this valuable instrument was intendec to be applied to a useful purpose, and he referred to expriments now going on at Woolwich to test the respective pwers of slow and fast burning powder. The results, so fac had shown that the time taken by the slow burning powdo* to project a shot a certain space was five times that of fas-burning powder ; that the velocity of the two, at the mu-zle of the gun, was about equal, and that the pressure of tie fast-burning powder acting on the gun was about doubfe that of slow-burning powder. Electrotype plates for prining were made at the same time, without mutual knowldge or concert, by Professor Jacobi, of St. Petersburgh, anc J. C. Jordan, of England, in 1839. Patent Safety Apparatus for Steam Boilers* Steam power is now so generally used that any thing con etructed for the purpose of promoting safety must be regarded with much interest by almost every one. It is doubt less the case that many of the accidents occurring to steam boilers are the result of a lack of water at some time, and which might be prevented if a reliable alarm were in use The engravings presented herewith illustrate safety appliances, by the use of which, it would seem, much of accident and repair might be avoided. Figs. 1, 2, and 3, represent a water alarm, the novelty ot which consists in the construction and operation of the valve, and also that they are self-detectors, as it seems impossible that they can get out of order without at once showing it— a fundamental requisite for safety in use. The valves and springs shown are similar in all, the levers which move them being operated by floats under different arrangements. 149 Fig, 1 is simply a low-water alarm. A is a cast-iron case about eigbt inches long and six inches wide at the large end, and has a clear space or chamber inside three inches wide. B is a copper float five inches long and two inches diameter (coated inside and out with a non-corrosive metal), which hangs loosely on a pin, by lever, C. The valve is seen held to its seat by the conical spiral spring. D is the knob on which pressure is applied to test the valve. Operation.—Being attached to the boiler by a single pipe, while the water in the boiler is above said pipe, the case is full, but if the water in the boiler falls below the pipe the water in the case falls out, the float drops, the lever, C, strikes the valve stem, tipping the valve on its seat, and steam rushes through and sounds the whistle, E. Start the pump or injector, and as the water rises by the pipe, the case fills, and the instrument is quiet again, ready to repeat the operation ; no expense is incurred and no attention required. This is shown connected to a T, in which is also one of the gage cocks, which is found to be a favorite way to attach them, as it is then unnecessary to bore the boiler—simply using a nipple and T in the same hole where the gage formerly was. Fig. 2 shows an alarm both for low and high water, and is connected to the boiler by a steam and water pipe ; thus the water in the instrument will bo on the same level as that in the boiler. A is a cast-iron cylindrical case sixteen inches long and four inches in diameter. B is a copper float—three and a half inches diameter, constructed as in Fig. 1—suspended from the lever, C, by the wire frame, E, and chain, F. D is a weight which keeps the lever, C, in a horizontal position when not being acted on by the float. The chain is constructed of German-silver wire and of round links, so it can neither corrode readily nor kink. The valve and spring are seen the same as in Fig. 1. H is the high-water, and L the low-water alarm line. When the water falls the float pulls down the lever, C, tipping the valve ; and when it rises too high the float strikes the frame, E, the lever is pushed up, and the valve is tipped the other way, causing an alarm in either case. By pressing on the knob, I, the whistle is sounded at pleasure. Fig. 3 represents alarms for low water and high steam—or either alarm may be used separately—the whistles being separate and having different sounds, so as to avoid confusion. A is a cylindrical case of iron or brass, about eight inches long and three inches diameter, in which is supended a float, B—the same as B, Fig. 1—by compound levers, C and C. The same construction ot valve and spring aa in Figs. 1 and 2 will be noticed ; D is a sma,ll spring safety valve—the valve is the same as in the water alarm, but is on the top of the seat instead of the under side. E is a lever and pin for try- ing the valve. J is a cup and pipe to carry off any drip from the valve ; G is the steam connection, and H the water con-' nection to the boiler. This instrument may be attached so that the water in it will be on the same level as in the boiler, or so that the alarm line for low water will be at the point of connection as in Fig. 1. The operation is similar to the others, and will be readily understood without further description. The high steam alarm simply sounds the whistle as the pressure becomes strong enough to raise the valve which is set by a screw to the required pressure. Fig, 4 shows a locked safety valve, the novelty in which consists in the construction of the valve and seat. In Fig. 5 the same valve is shown constructed so as to be applied to the dome cap of a locomotive, of which I is a section. As Fig. 5 shows a vertical section of the valve it can be better described by it, and the operation is the same in both. A is the valve ; B, guide wings on top of the valve and connecting the concave disk, C, thereto. D is the rim, against which the guide wings bear. E is the guide pin to the valve. F is the guide nut. F' is tho guide nut braces. G the wings to strengthen the guide pin, E. His the annuia) passage for steam around the valve, by which the steam is turned up against the disk, C. K is a lever of any suitable length for trying the valve. The valve is held down by the spiral spring, L, and set as re- quired by the crosshead, M, and bolts and nuts, N N. The result being a safety vaVe that will rapidly discharge the surplus steam and cause no waste by blowing the pressure lower than when the vahe commences to alarm. Operation.—When th valve. A, begins to rise, the steam will pass through the narrow space (about one sixty-fourth of an inch) between the div, C, and rim, D. If the pressure then rises, say a couple cf pounds higher, the valve opens wider—while the space beween the rim and disk has not increased, the sides being vertical—and more steam will pass into the passage, H, than an pass by the disk, C; then the whole force and velocity of the escaping steam will be exerted on the disk carrying it luddenly upward, with the valve, overcoming the increased per of the spring, and permitting the steam to blow off npidly until the pressure has fall- en to near where the valve started to alarm, when it will suddenly close, thus simply blowing off the surplus steam. Fig. 4 shows the valve as it is locked in a case (the whole hight of the holder and cover being about eleven inches and a half, and about six inches diameter). It cannot be tampered with. without violating some of the parts, thus apparently preventing, as far as can bo done by machinery, an over-pressure of steam. The water alarm was patented Feb. 11, 1868, and the safety valve May 18, 1869, by J. D. Lynde, 403 North 8th street, Philadelphia, where he can be addressed for further information. Hammering Iron until U is Med Hot, In his lectures on " Heat," delivered recently at the London Institution, Mr. G. F. Rodwell alluded to a singular case of motion transformed into heat; namely, the rendering of iron red-hot by repeated strokes of the hammer. If Mr. Rod well, who is so well versed in the history of science, will turn once nore to the works of Robert Boyle, he will see that this " father of chemistry " had notions of the transformation of mechanical movement into heat very nearly akin to, if not quite identical with, those professed at the present day. Robert Boyle alludes to th(3 rapid development of heat in an iron nail by repeated blows of the hammer after it Jias ceased to travel into the wood. It has been asked whether iron could be ham mered cold until it became red-hot. Mr. Rod well informs us that it can. Having requested a blacksmith to try the experi ment, a piece of very tough iron was hammered with a mod eratcly heavy hammer ; it became hot, but would not scorcli a piece of papsr. It was then hammered by two men, one of whom usod a sledge hammer, but with no better result. Presently a man, who was working in the shop, said he had often lit his forge fire by this means before matches were plentiful. He took a nail such as is used for horseshoes, and, after hammering for less than two minutes with a light hammer, part of the nail was brought to a bright red heat. The blows were light but frequent, and the nail was partly turned at each blow.