FAIRBAIRN'S OPINION OF CORT'S INVENTIONS.

66

a

MR. WILLIAM FAIRBAIRN, in his able work on iron, reviewed in our last number, says Mr. Cort obtained two patents, the first in 1783, respecting peculiar method and process of preparing, welding, and working various sorts of iron, and of reducing the same into uses by machinery, and a furnace and other apparatus adapted to the same purpose." In February, 1784, he obtained a second, comprising "shingling, welding, and manufacturing iron and steel into bars, plates, rods, and otherwise, of purer quality, in larger quantities, by a more effectual application of fires and machinery, and with a greater yield, than any method before put in practice." His first patent comprises methods of faggoting bars for various kinds of uses, the hammer and anvil being employed, and the faggots brought to a welding heat in a balling furnace instead of one with a blast. By passing faggots through rollers, "all the earthy particles are pressed out," and the iron compressed into a tough and fibrous state. Bars of bad quality may be improved by rolling, and several bars rolled together become perfectly united. He points out that iron plates may be made in the same manner. He shows how the shape and dimensions of the plates and bars may be determined by collars and grooves in the rollers, In this patent we see, therefore, he has developed his system of faggoting and heating scraps and bars, and welding them into a mass, and compressing them into form by means of rollers and hammers. And the introduction of rollers in this process was a step in discovery we owe to him. There was still wanting a process for the production in this country in large quantities of the wrought iron itself. This he provided in his second patent. He introduced a reverberatory furnace heated by coal, and with a concave bottom into which the fluid metal is run from the smelting furnace; and he showed how by a process of puddling, while exposed to the oxidizing current of flame and air, the cast metal could be rendered malleable. He describes in his patent the stirring of the metal till ebullition ceases, and its collection as it becomes less fusible into blooms, the hammering of these to get rid of the slag, and their reduction to a marketable shape by the processes described in his previous patent. It would be a difficult task to enumerate all the services rendered by Mr. Cort to the iron industry of this country, or sufficiently to express our sympathy with the relatives and descendants of a man to whose mechanical inventions we owe so much of our national greatness. It is, perhaps, not generally known that Mr. Henry Cort expended a fortune of upwards of £20,000 in perfecting his inventions for puddling iron, and rolling it into bars and plates; that he was robbed of the fruit of his discoveries by the villany of officials in a high department of the Government, and that he was ultimately left to starve by the apathy and selfishness of an ungrateful country. When these facts are known, and it has been ascertained that Mr. Henry Cort's inventions have conferred an amount of wealth on the country equivalent to six hundred millions sterling, and have given employment to six hundred thousand of the working population of our land for the last three or four generations, we are surely justified in referring to services of such vast importance, and in advocating the principle that such substantial proofs of the nation's gratitude should be afforded to rescue from penury and want the descendants of such a bene: actor.

ELLIOTT'S ANEROID BAROMETER CASES.

THIS invention, by Mr. F. H. Elliott, of the Strand, London, mathematical instrument maker, consists of a fixed cover, with a portion thereof cut out or removed over a portion of the scale on the dial, and of a moveable cover, with a similar portion also cut out or removed. A circular aperture is made in the centre of the moveable cover in which a plate with a tail-piece of no greater thickness than that of the metal of which the moveable cover is formed is free to turn; an index or pointer is connected to this plate, and by turning the tail-piece the index can be set and moved as required. The

side of the moveable cover is slotted to enable it to be turned over screws or studs and over the fixed cover. When the moveable cover is so turned as to expose the portions removed from both covers, so much of the scale on the dial as is requisite is exposed to view, when the moveable cover is turned partially round the aperture in the fixed cover is closed. Figure 1 of the accompanying drawings is a side elevation of an aneroid barometer fitted with a case made according to the invention. Figure 2 is a plan of the same, showing the scale protected by the moveable cover, and figure 3 is a plan showing the moveable cover turned to expose the scale to view. a is the fixed cover having the portion from 6 to c cut out, d is the moveable cover, e is the plate with tail-piece ƒ fitted in a

circular recess sunk in the central part of the moveable cover; g is the pointer fitted to the plate e; h is the portion of the scale comprised between the parts bc; ie are the slots formed in the side of the moveable cover; k k are the screws or studs screwed to or fitted in the side of the fixed cover, over which the moveable cover is free to travel. The length of the slots ii is regulated in such manner that when the moveable cover is turned in one direction, so as for example to expose the scale to view, the studs abut against the termination of the slots, and vice versa. is a tug made with a hole in, made to slide at the back of the case for the purpose of hanging up the barometer when required. For carrying in the pocket the lug is pushed inwards as shown by the dotted lines.

MR. W. F. SNOWDEN, of Gray's-inn-road, machine maker, has just obtained a patent for certain improvements in the arrangement of the driving parts of chaff cutters, the object being to simplify the construction of such machines without detracting from their efficiency.

In the accompanying engravings fig. 1 shows in side elevation so much of a chaff cutter as will serve to explain the nature of the improvements; fig. 2 is a front view of the same, the cutting wheel being removed from its shaft; A is the framework; B is

the ordinary crank shaft, and C C are the feed rolls. In order to obtain the intermittent feed motion necessary for preventing the material to be cut being driven against the knife or knives of the cutting or fly-wheel D while in operation, the inventor keys on to the axles of each of the feed rolls a ratchet wheel a, and these wheels are driven in opposite directions by means of clicks b, b, carried by rock levers, c, c. These levers are situated one on either side of the ratchet wheel of the upper feed roller, and their forward ends rest on a stud carried by a vertical bar

pendent from the framing A, and adjustable for the purpose of raising or lowering the stud by means of a nut e working on the tapped or threaded end of the bar. The rock lever c has its fulcrum on the axle of the upper roller, and to its rear end is jointed its click b. The other lever has its fulcrum on the side framing; at their forward ends these levers are coupled together by a pin from one entering a slot made to receive it in the other. Jointed to the lever c is a pendent arm, which carries at its lower end the weighted click b. Situate near the foot of the machine is a lever E, which has its fulcrum in the framing at f. This lever is connected to the crank shaft B, and receives an upward motion therefrom through the crank rod F. Jointed to the lever E is a vertical rod g for operating the rock levers. This rod g carries at its upper end a stud which, as the rod ascends, will strike against the forward ends of the rock levers, and cause them, through their clicks and the ratchet wheels a, a, to impart a slight rotary motion to the feed rolls.

The amount of this axial motion of the rolls, which determines the length of feed, is regulated by the nut e on the threaded end of the adjustable bar by which nut the bar is supported in position. Connected also with the lever E at the foot of the machine, by means of a coupling rod h, is the ordinary presser frame and board, which holds down or presses the material while the cut is taking place, and rises to allow of the material being fed forward after every cut, as is well understood. In order to permit of this presser adjusting itself to a greater or less thickness of feed, the coupling rod of the presser is jointed to a spring i attached to the lever E, instead of connecting it directly to the lever, which receives an unvarying amount of movement from the crank shaft. By this arrangement the pressure put on the feed will be that of a yielding spring, which will accommodate itself to the thickness of the feed. A sliding strap i is provided on the lever for the purpose of regulating the resisting force of the spring. To assist this spring i in maintaining the pressure on the feed when a larger, supply than usual is brought under the passing board, an additional spring is provided below the lever E, which spring is bowed, as shown, and passed through the strap of the coupling rod h. Its use is to bear upon a cross pin in that strap, when by reason of an excessive supply of hay or straw the pressure commences to throw an undue strain upon the spring i, and thus to relieve the upper spring of a portion of the strain, which it would otherwise have to sustain.

DEAVEN'S GYMNASTIC INVIGORATOR.

Platinum (commercial)

0 to 00332

0

00301

0

00273

00222

00220

00199

00138

00133

00119

00112

00103

00098

00088

0

On comparing these co-efficients with those found by previous experimenters, we find that they agree very closely in those cases when commercial metals have been employed. But when we come to those metals which we employed in a pure state, such as lead, tin, zinc, silver, cadmium, bismuth, antimony, and gold, we find a marked difference, which we attribute to our experiments having been made with pure metals, and we are confirmed in this view by the following experiments :

We found that a small per centage of impurity (such as 3 or 4 per cent. in iron) produced a considerable deduction in the ratio of expansion.

Wrought Iron as in preceding Table. Co-efficient of expansion 0-00119 Ditto of iron crystallized by vibration... 0-00108 these facts on account of the great use which is made We have been led to devote particular attention to of these metals in naval and other constructions. Although we have only given one example of the influence of crystallization upon the ratio of expansion of metals, still we have observed several others in the course of our experiments upon metals; and in further researches upon minerals and rocks, which we shall shortly publish, this influence will be strikingly exemplified.

Another example of the influence of molecular condition upon the ratio of expansion is the change which takes place in steel when tempered at different degrees of temperature, showing that a slight change in the arrangement of the particles of a body affects its ratio of expansion.

The steel bar upon which these experiments were made was nearly double the length of the bars used in the previous experiments. The figures here given are those read off in the same manuer as those previously detailed; but the mean for 100° is calculated, and the correction applied to reduce it to the mean for a bar of 60 millimetres in length, for the sake of uniformity.

THIS very ingenious invention of Mr. M. Deaven, of 28, Crystal-terrace, Rotherhithe, S.E., consists in adjusting the ordinary see-saw on its fulcrum, by means of racks and pinions, so as to equalize the various weights of children, who can easily work it themselves by means of cords attached to the perpendicular central stand. The seats are secured at either end. There are several erected at the Crystal Palace, where they are much inquired after, and engaged by old and young; and we hear others are to be erected at the Cremorne s and other places.

Mean.

Same bar, at maximum 141.0 145.0

of hardness...

THE CAUSES OF BOILER EXPLOSIONS. A VERY important law-suit, involving the solution of the above problem, has been before the law courts in the United States for nearly three weeks. We copy the leading points, and more important details of the case, from the American Railway Review:Mr. Wheeler Beer, of Bridgeport, Conn., brass founder and machinist, ordered of Messrs. Woodruff and Beach, of Hartford, Conn., engine and boiler builders, a 10-horse vertical boiler, of a particular style. No dimensions or proportions appear to have been mentioned, the requirement being a good boiler, calculated for a working pressure of 75lbs. The boiler consisted of a shell 48 inches in diameter and 7 feet high. It had an inclosed fire-box 30 inches deep, after the manner of ordinary vertical tubular boilers. From the crown of this, three plate flues of 9-inch diameter, and about a foot length, ran vertically to a cross or horizontal flue, passing from side to side of the shell, and 15 inches in diameter. Above this were the water level and steam room. All parts of the boiler, except the upper head, appear to have been made in an unexceptionable manner. But this top head, 48 inches in diameter, consisted of a single flat disc of cast iron, 17-inch thick in the body, with a still thinner flange, which turned down for some three inches all round, and to the outside of which the cylinder was riveted. The thickness of the head through that part of the corner, all round, where a fracture would be likely to occur, was from 1 to 1 inches. There were no flues, nor stays, nor other connections, between the head and the shell, except the cast iron flange of the head.

The boiler was furnished and put up in February, 1857, and in November, 1857, shortly after the attendant had left it, at noon, the head blew out, the fracture occurring in this corner, 13-inch through, all round; and the three-story building in which the boiler was situated was thrown down, almost completely, a part of the walls falling inward, and a part falling outward. The pressure at first carried on the boiler was 72lbs., and the pressure ordinarily carried at the time of the disaster was 52lbs. The attendant states that, when he left the boiler, there

were between two and three guages of water; that the fire-door was open, and the chimney damper closed. Mr. Beer brought a suit against Messrs. Woodruff and Beach for damages, on the claim that the boiler was unskilfully made, bad, and unsafe; that it burst from the gradual weakening of the too thin and unsafe cast iron head. The defence claimed that they had made some hundreds of boilers on this plan; that none of them had blown up; that it was a safe boiler, and that the explosion resulted as follows:-The water was low in the boiler; steam became superheated; the safety valve opening to relieve the pressure, sent up spray or water into the superheated steam and generated fresh steam of sufficient pressure to explode the boiler and do the damage; in short, that the result was due to carelessness on the part of the attendant. On this basis the case was tried, and the jury did not agree, but stood six and six.

The case was then better prepared on both sides. An array of legal and engineering talent, experience, and learning was engaged, and the matter was brought to trial in the Superior Court held at Bridgeport, Judge Hall on the bench.

On the part of the plaintiff the testimony of the boiler makers generally was, that the cast-iron head was unsafe; that the casting must have been weakened to some extent in cooling owing to unequal expansion, that the riveting of the shell upon the flange (which had considerable bevel or draft), and also the caulking, added to this weakness; and that the vibration of the head, under its different pressures (47 tons total, under 52lbs. of steam), contributed to the gradual "fatigue" of the metal in the particular angle where it broke, until its giving way, was a perfectly natural result. Some cases were cited in which cast iron, having been overstrained, at last give way under less pressure than they had previously sustained. It was their opinion that a deep fillet should have been put in the corner, so as to have increased its thickness to some three inches, or that some sort of stays should have been supplied, not trusting to any cast iron corner for the sole resistance to such a pressure. It was further proved by tests made in Bridgeport, and at

Alger's, in Boston, that the iron of this head was only capable of sustaining 11,500 to 13,000lbs. per square inch, the best cast iron running as high as 45,000lbs., and consequently that not only the construction, but the material, were of the poorest description.

On the part of the defence it was proved that a large number of heads from this same pattern had been made for heating purposes, and intended to carry the same pressure, and that a head had been cast from this same pattern by way of experiment, and subjected to as many vibrations, under the more severe pressure-cold water forced in by a pump-as the broken boiler head could have sustained, and that it finally broke at 190lbs. per square inch. It was pronounced safe by the United States' Supervising Inspector of steamers for the New York district, and by Mr. Martin, to risk any head for a year that had sustained one-half greater pressure than it was designed to work under, for this is the highest guarantee required by law. It was further shown that the cast iron cylinder heads of marine engines generally, are known to spring more frequently than this boiler head did, without breaking, and that several particular heads of about this size did spring more in extent, and several millions more times than this boiler head did, without breaking. It was laid down in Professor Renwick's book on boilers, that about this thickness of head was customary at the time when this pattern was made. As to the quality of the iron, it was stated by the defendants and persons in their employ, that what was supposed to be a good quality was selected. The question of leverage on the head was gone into at great length. Mr. Byrne proved algebraically that the force on the whole of a disc was equal to one-third of that force applied at the central point, and that the leverage could be got at in that way. We may remark that this same law was demonstrated geometrically by one of the outsiders, and that it is undoubtedly correct, though not laid down in the books. Then the position of the neutral axis, in the fracture, was the subject of considerable discussion. That would of course reduce the area of the metal exposed to tensile strain. If the neutral axis was removed -inch from the outer edge of the fracture that would be the short arm of the lever, while the long arm would be 200-8 long. But it was strongly urged in the defence that cast iron was the only absolutely elastic metal, up to the limit of its elasticity, and that that limit of elasticity could not be proved to have been reached by any vibrations which the head had sustained. And it was further urged by them that not a very great strain could have been left in the casting, because the cope had been removed immediately after the pouring of the head, thus exposing its flat top to the air, so that the cooling all over would have been substantially alike. A large amount of collateral evidence bearing on these various points, but which we have not space to mention, was introduced.

The question of explosion and rupture was discussed at length. The testimony was, that explosions may generally be named by their results-that their sound is like that of a cannon, and that they almost invariably break and rip into pieces, the strongest as well as the weakest parts of boilers never confining themselves only to the weak parts. They always show the instantaneous generation of an immense power. Ruptures, on the contrary, do not make a noise like that of a cannon; they confine themselves always to the weakest parts; and the pressure being instantly relieved through the comparatively small opening made, no farther damage is done. This is always the result of a rupture under hydraulic pressure, or when a rupture in a boiler occurs under the water level. It was shown, however, that when a rupture occurred in the steam-room of a boiler, under steam, from bad construction or material, or from over-pressure, the steam instantaneously generated by reason of this release of pressure might. carry up a large amount of water with it, and in some cases do as much damage as an explosion of any kind might be expected to do; and it was urged that the momentum of the head itself, weighing some 700lbs., under 47 tons initial pressure, might, in striking the beams above, have thrown down a slightly-built and, to some extent, recently completed brick structure, in which much of the mortar was green.

The defence at length proceeded to account for the explosion by superheated steam. Since a considerable amount of substance looking like whitewash had been thrown across the street and splashed upon various objects about, it was urged that this was lime from the water of the boiler, and that the boiler was, therefore, unfaithfully attended, and that it consequently foamed, deceiving the attendant, so that he could not tell where the water was-hence, that there was low water, and that superheating ensued. It was shown, on the contrary, by Mr. Winslow, master mechanic of the Housatonic Railroad, who uses the same water

(from the city waterworks) in his locomotives, that it is the best water he ever saw, and that his dock engine, using this water only, is blown off only once in four to six weeks, and that it never has any scales. Mr. Beer swore that he blew his boiler off once in four to six weeks. And it was sworn, by the engineer or attendant, also, that there were two to three gauges of water in the boiler when he left it.

Experts were nearly unanimous in the opinion that steam is superheated in the steam chimney's of steamboats, and in vertical tubular boilers, and at all times when there is low water; and that the sudden rising of the water surface would create the instant generation of steam and use of pressure by the heat of the superheated steam above. Mr. Martin gave some details of the experiments on the Collins' steamer Arctic, wherein Wethered's mixed, saturated, and superheated steam was tried, but he did not state how much the pressure was raised. The plaintiff had proved that the boiler showed no signs of heating; that it had a wrought iron drum head put in, without farther repairs, and was still in use. Mr. Martin stated that Wethered's superheating pipes, after four months' use, were sawed up and examined by him, and found perfect.

hence the total amount that can come out of it to vaporize more water. The water in the boiler now being, as it was before, at a temperature of 300, it will take 900 units of heat to vaporize each pound of it, because there are 1,200 units of heat in a pound of steam, a part sensible (300° in this case) and the balance latent. By dividing all the units of superheat we have by the number of units required to vaporize each pound of water, we find that only 1-8lbs would be vaporized, making, of course, the same weight of steam. Now, the volume of 1lb. of this steam is 8.31 cubic feet x 1-8-14-95, say 15 cubic feet of steam made from all the superheat, supposing enough water to have been mixed with it, from any cause. The increased pressure is then a matter of simple proportion:

60 c. f.: 50lbs. pres :: 15 c. f.: 124lbs. pres. Thus 124lbs. increase of pressure per square inch, or 624lbs. in all, would be the total result of superheating to 600°. By the same calculation, it would follow that in an ordinary locomotive boiler, under, say 140lbs. pressure, superheating to 600° would only raise the pressure to 175lbs.

As to the effects of suddenly releasing the pressure But the superheating theory, admitting that there from the surface of the water, by the rupture of the was low water, and that the safety valve suddenly head, before referred to, the facts would be these. opened, causing a mixture of water with superheated Supposing the water to be at the usual level, there steam, was entirely upset by Mr. Holley, taking the would be 25 cubic feet of it x 62lbs. (its weight per doctrine laid down in the books, about the specific square foot)=1,550lbs. There are, at 50lbs. pressure, heat of steam to be true. That this generally- 300 units of heat in each pound. When the pressure admitted doctrine is true, he did not attempt to assert; is removed, only 88 of these will be set free, since 212 but till it is, as indeed it possibly may be, disproved must be left, as water will not vaporize below the by farther investigation, there is no other possible boiling point (300-212-88). There are 1.550lbs. of conclusion than that any probable amount of super-water, x 88=136,400 available units of heat in all the heating cannot cause an explosion. water. Each pound of water has 212 units, and must have, say 990 more (212+990,-1,202 total units in one pound of steam) to be vaporized, hence 136,400 990-137lbs. water vaporized. As all this water instantly expands 1,700 times its bulk in the form of steam, it must take up with it a large portion of the remaining water, at an immense velocity, and this water, acting like innumerable projectiles, and added to the momentum of the head, might well account for the damage done. This theory of explosions is ably set forth by Mr. D. K. Clark, in the "Encyclopædia Brit.," 8th ed., vol. xx.

This boiler was calculated to contain, with very low water- so that most of the heating surface was

exposed to the steam-60 cubic feet of steam. Now, suppose the working pressure, say 50lbs. per square inch, to have been maintained. The heat of the water and of the steam, due to that pressure, would have been some 300°. The volume of steam at this pressure, that is to say, its relative size as compared with the water which made it was 518. The weight of 1 cubic foot of this steam was (62lbs. water in 1 cubic foot divided by 518 the volume), say '12 of 1lb. by 60 cubic feet of steam in the boiler, are 7.20 or say 8lbs. of steam by weight. Now, it is laid down in all the books that the specific heat of steam is about that of water, that is to say, that the amount of heat that will raise one pound of water one degree will raise 3lbs of steam 1 degree, or that a pound of steam, at a given temperature by the thermometer, has only got as much free heat in it as a pound of water. A unit of heat is a unit of definite measurement, just as much as an inch or a pound; and it is the amount of heat that will raise one pound of water one degree. Hence, of a unit will raise a pound of steam one degree. Now, suppose we superheat this 60 cubic feet or 8lbs. of steam, to 600° above the temperature due to the pressure (i.e., to 900°, as indicated by a thermometer), it takes of a unit of heat to raise each pound of it (the steam) one degree, and hence, it takes 200 units to raise each pound of it 600°. Then, 200 units x 8lbs. 1,600 of heat, as the total amount of heat in m that was put in by superheating, and

=

It may be observed that the superheating theory, in the summing up, was substantially dropped by the defendants, and that the explosion was attributed, any how, to low water. The defendant dwelt on the fact of his using all reasonable care in the selection of material and in construction, and that the boiler had actually stood what would be required by government inspectors-also that the injury by vibrations was all theory without any definite facts or calculations to support it, and with some strong facts to the contrary; therefore that he was not responsible for damage, however it arose, and which did probably arise from careless management. The plaintiff, on the contrary, insisted that the iron was the worst known; that the construction was pronounced faulty by boiler makers; that the head was bound to give way sooner or later under even a decreasing pressure, and that the defendants' theory of explosion by superheated steam was all moonshine, even if the conditions had existed to superheat the steam. And here the case stands till the jury agree-or agree as before-to disagree.

W. ROBERTS'S PATENT PORTABLE FIRE ENGINE.

THE advantages of this engine are:

1st. Great power combined with portability. 2nd. Simplicity of construction, and consequent non-liability to derangement.

3rd. Ready access to the interior (the whole of the working parts can be got at in two minutes).

4th. An engine with 12ft. of suction and 120 ft. of delivery hose, and all the gear complete, can readily be transported over ordinary roads by one

man.

5th. Will throw 60 gallons of water per minute a distance of 80 ft., with eight men working, and 103 ft. with ten men.

6th. The carriage can be disconnected from the pump in eight seconds, and connected again in twelve seconds.

An engine of the above size has been taken from the engine-house, through the factory to the water, a distance of 110 yards, 90 ft. of delivery hose run out, and the pump got fairly to work in three and a-half minutes. When the pump is disconnected from the carriage, it becomes a portable pump for ships' use, and can be used with a suction plate, to which it can be connected in a few seconds, and thus obviate the necessity of having standard pumps upon the decks of gunboats or small vessels, where a clear deck is a desideratum. It is equally applicable for any purpose where a lift or force pump is required."

The following is a description of this portable fire engine:

A, pump having one suction at a, through the side, and another in the bottom, which (the bottom) is screwed in the cylinder, also two deliveries, al a1, the air chamber A1 being screwed on the top, thus affording a ready means of access to the interior. B B, levers with wood handles, b b.

C, plank or bed, having an axle hooked at the ends, c c, and at the end of the plank a plate, C1, with a latch, C2.

DDD, frames either of metal, or metal and wood, combined.

E E, suspending rods working between the upright frames, upon bolts, at e e, the lower ends being hooked. F, rod having a T foot, and connected with the frame at f

G G, hose reel working upon the axle freely, between the side frames DD DD, and upon which the hose is coiled. H, a box to carry the branch pipe, jets, spanners, and all the necessary tools. The suction hose can be carried upon the bed C, at each side of the pump, or beside the box H, or both, if a long length is required.

I, canvass well or cistern.

When used for horse traction, a seat is fitted to the frame, to carry the driver and three firemen. The seat folds down upon the frame when not required.

Upon reaching a fire the latch C2 is thrown back, and the foot of the rod F withdrawn from the slot;