The Iron Age 1889-12-26: Vol 44

HE THURSDAY, DECEMBER The Pulsion Mechanical Telephone. A new mechanical telephone of extra- ordinary power has recently been excitiag considerable attention in London. A cor- respondent of Nature describes it as fol- lows: It is of American origin, like so many other modern improvements of exceptional character, being the invention of one Lemuel Mellet, I believe, of Boston. There have been many previous mechanical telephones, as your readers are aware, some of which have obtained much pub- licity for a short time, and then have been heard of but little more; but having had opportunities of experimenting fre- quently with the new instrument and ebserving its vocal power, so to speak, under very various circumstances, I can- not doubt it has a great future before it. It may be clearly stated at once that the pulsion instru- ment is absolutely inde- pendent of all electrical aids or appliances, and therefore needs neither bat- tery power to bring it into play nor insulation of any of its parts tc keep them effective. It consists solely of two cheap and simple instruments con- nected by an ordinary non- insulated wire of copper, or, better still, of a double steel wire, the two parts being slightly intertwisted, say with about a single turn in a couple of feet. The wire (or wires) is sim- ply looped to the instru- ment at either end, the connection being made in a fewseconds. The instru- ment consists of a disk in combination with a series of small spiral springs in- closed in a case of some 3 or 4 inches in diam- eter. These springs, ar- ranged in a manner that has been determined by experiment, and so as to produce harmonized vibra- tions, appear to possess the power of magnifying or ac- cumulating upon the wire the vibrations which the voice sets up in the disk, and the wire seems to possess—undoubtedly does pos- sess—the power of transmitting to great distances and giving out upon a second pulsion instrument the sounds of tHe voice. The ability of this simple system of springs, disks and wires to convey con- versational and other sounds to consider- | able distances with great clearness and distinctness, reproducing the very tones of the voice and the qualities of musical sounds with but little reduction or modi- fication, is most surprising, and to none more so than to the many men of science who have been recently experimenting with it. The writer of this notice can- not, perhaps, do better than state his own | experiences with this system. After ex- amining and experimenting over several short lengths of wire, some of | them exceeding a mile and a half, he last week went to the Finch- | ley Road Station of the Midland Rail- | way, from a point near to which a line had been conveyed to near the Welsh Harp 26, 1889. of the wire, which for the larger part was carried hy the telegraph-posts, to which it was attached by very simple means. Con- versation through this leneth of line of over three miles was exceedingly easy. Indeed, so powerfully was the voice trans- mitted that an ordinary hat sufficed for all the purposes of the second instrument without going near to which conversation was carried on repeatedly by means of the | hats of three gentlemen who were present, the tops of which were merely placed against the telephone-wire. I then went into the Welsh Harp, where a short length of wire had been led between two points, the Wire on itS way other being twice tightly twisted, at an interval of yards, round branches of trees of about 1 inch some in di- UNIVERSAL MILLING-MACHINE. ameter, being wound round and round the branch three times in each case. Strange to say, this tight twisting of the wires round the branches in no way interfered with the transmission of the voice |from end to end of the wire. A third jand last experiment was made with a | wire laid obliquely across the Welsh Harp Lake and allowed tu sink to and rest upon |the lake bottom. The length of the line was roughly estimated at about one-third of a mile, and from end to end (excepting a few yards at each end where the wire was led from the water’s edge to the telephone box) the wire was completely immersed, and without any other support than the bottom of the lake offered it. Yet, notwithstanding this immersion of the whole wire, conversation was |carried on through it by means of the pulsion instruments without the least diffi- culty. In fact, the voice came through the immersed wire, and the longest wire (of over three miles) previously mentioned, with greater purity and mellowness than through shorter lengths. I must leave to Station, a distance of three miles by the line of railway and of more by the track others to explain, and if necessary to dis- cover, the scientific grounds of the success IRON AGE garden of the! from one point to the | |machine_ tools. small i slack in the worm. leut a of this extraordinary little instrument. Looking, however, at its practical capa- bilities as exemplified above, it is not sur- prising that post-office, police, railway and other commercial people are already overwhelming with applications those who are arranging to supply the new telephone, which, from its extreme simplicity, is manifestly a cheap one. —_—— Milling-Machine. Universal The machine of which we _ herewith present several illustrations has been de- signed to meet the most exacting demands of work peculiar to this important class of The spindle is of large diameter, having a front bearing 4, inches long and 24 inches in diameter. It is hollow and will allow the passage of }4-inch stock. Both shoulders at the front bearing are provided with hardened and ground anti- friction washers, and both bearings have ample adjust- ment for wear. The front end is threaded for the chuck, which fits the spiral head, and the rear end car- ries the feed cone. The table is 31 inches long and has a bearing of 15 inches in the swiveling-block. The T-slot extends the whole length, and both ends of it are accessible. The table can be fed 17 inches by power and 22 inches by hand. It has an adjust- ment to and from the face of the column of 6 inches and a vertical adjustment of 153 inches. It can be swiveled 45° either way from the straight position. The screw is arranged to take gears for either simple or compound trains, and is provided with a compensat- ing nut to allow for wear. The elevating and cross- feed screws are each pro- vided with index circles reading to thousandths of an inch. The spiral head has an extended base and two holding-down bolts, insuring great solidity. The spindle is hollow and will take in$}}-inch stock. The taper socket in the spindle allows the interchange of tools between it and the main spindle. It is also fitted with a three-jawed universal chuck. The dividing worm-gear is provided with a patent compensating wedge, which per- mits instant adjustment of the amount of Three index-plates are provided, by the use of which all num- bers of divisions up to 50 can be obtained, and all up to 360, except a few prime numbers. The gearing is designed to large number of spirals of even pitch, such as one turn in 14, 2, 2}, 3 inches, &c. The manner of adjusting the gearing is very convenient, ani the entire range of spirals from one turn in 1.33 inches to 133.33 are cut with a set of but eight change gears. The head will swing 104 inches and a spiral 14} inches long can be cut. The tail-stock is of new form and very solid design. The supporting point is close to the top, enabling cuts to be taken close to the center. The clamping device operates without altering the align- ment of the centers. The feed has three changes and operates with perfect freedom cr iP CRE BRR IR aces wee sim ii e ce - . : ome 5 ere 4 , f i“ SiS be B. at whatever angle the table may be set. The feed mechanism is not carried by the table, but is attached to the swiveling- | block; this keeps the feed-rod always in a straight line. The feed-trip is very readily adjusted and operates with the table run- ning in either direction. Each of the dividing worm-gears is provided with the compensating wedge, shown in Fig. 2. The threescrews f hold the two parts of the gear together, but do Nyy ty? } l ff oe l ( ry uy \ y) ——_ ia ) fy P| a) —_—_— tf K i] HJ Th j ‘7. Jt | SY Ld Fig. 7.—Milling the T-Edge. Fig. 3.—High-Speed Attachment. not bind. The wedge « takes all the strain between the parts of the gear. The screw 6 can be reached through a hole shown immediately under the hexagon nut in the back of the spiral head, Fig. 8, when the mark O on the front end of the spindle is on top. Turning the screw to the right tightens the gear on the worm. The difficulties that have heretofore been inseparable from this form of worm-gear are overcome by this simple device. The wedge forms a solid connection between the two parts of the gear, and at the same time furnishes the most handy and accu- rate means of adjustment. THE IRON AGE, The high-speed attachment is designed | to fit either the No. 1 or 2 universal mill- ing-machine or the No. 2 or 3 milling-| machine built by the same makers, the Gar- vin Machine Company, of Laight and Canal streets, New York. By the arrangement of the gearing the secondary spindle runs four times as fast as the main spindle. This large increase in speed makes it pos- sible to use small and light cutters run- ning at speeds suited to their diameters. Fig. 5.—Milling-Gear Stud-Bracket. UNIVERSAL MILLING-MACHINE, | The cutters are held in a spring chuck in the secondary spindle. The spindle has a long bearing, insuring stiffness with smoothness of motion. The illustration shows the gearing with the protecting cover removed. The rack-cutting attachment will cut racks from 10 pitch to 32. It is readily applied, and when in position is as solid as if permanently attached to the machine. A vise, 17 inches long, for holding racks, accompanies each attachment, also the neces- sary indexing arrangement for cutting the |above pitches. The arbor runs in adjust- ‘able-cap boxes, and is { inch in diameter. Fig. 5 shows the bracket supporting the change gears. It is made of steel and 1s milled all over. Fig. 6 shows the operation of milling off the flat sides with the overhanging end supported by the center rest. Fig. 7 shows the use of small mills in milling the T-edge. These are preferably used in the high-speed attachment. Fig. 8 shows the spiral head mounted at right angles to the bed by means of the Fig. 4.—Rack-Cutting Attachment. extension-plate, and arranged for milling the outline and the slots in the face of the piece. It is evident that in the foregoing we have only given a few of the important uses to which the machine can be put. EE A bill before Congress authorizes the Secretary of the Treasury to pay to the heirs of the late John Ericsson the sum of $13,940, together with interest at 5 per cent. since 1857. The bill says this was the amount found to be due deceased in 1857 for designing the United States ship Princeton and work and material furnished in-her construction. December 26, 188% STEEL FOR BOILERS. KREUZPOINTNER, BY PAUL ALTOONA, PA, Since there is a growing disposition to dispense with iron and use steel for the manufacture of steam-boilers—a disposition which no doubt has been strengthened by the action of the A. B. M. A. by recom- mending steel for boilers—it may per- haps be of interest to all concerned to dis- cuss the merits and demerits, the quali- ties and properties of this metal somewhat in detail. Though the writer is aware that much has been written on the subject of steel for boilers by able and competent men, yet the subject has not been so thoroughly discussed as to settle the question in the anxious steel user’s mind whether all that ought to be is known in order to create such a confidence in steel for boilers as is claimed for it by its advocates. Fortunate- ly the experience with many thousands of locomotive and stationary steel boilers in use for many years furnish us with a mass of reliable data. As with boiler explosions, so with failures of steel for boilers, which, however, are rare, there need be no more mystery about them in the face of advanced knowledge than there is to explain any common accident. However, as increased experience and changes in metallurgical methods have added new data to those al- ready published by experienced authorities on the use of soft steel tor boilers, and since few steel users are fortunate enough to han- dle daily large quantities of steel of various grades from different makers, a few addi- | tional data to the accumulated stock of knowledge may be welcome to the readers of The fron Age, especially since these data are the results of careful investigation | and years of practical experience in regard to suitable qualities of steel for boilers. Although the writer is much in favor of steel for boilers and has never hesitated to advocate its use, publicly and privately, tor this purpose, he respects the conserva- tive feeling of many and readily under- stands the reasons advanced as an objec- tion to the proposed change. Iron has been in the past such a faithful and valu- able stand-by that it is but natural to hesitate to discard such a valued old friend before we are sure about the desir- able and undesirable qualities of the new one. To lessen the fears and anxiety of some and to caution the too sanguine to exercise prudeace by poiuting out defects in boiler steel which the steel maker and user alike will do well to avoid is the object of these lines, THE STIFFNESS OF STEEL. During the 29 years of the use of steel for boilers certain facts have been estab- lished in spite of the complexity of fac- tors which tend to deteriorate a boiler. Our industrial conditions more and more demand the economéc use of our natural resources and therefore a thorough knowl- edge of details in every respect. One reason why ‘steel encountered so much prejudice with the boiler-maker was its stiffness. Being denser than iron, steel does not yield so readily to pressure exerted by roll and hammer. Since the boiler-maker was used to the softer iron, which will stand more abuse, the new metal was ill treated and hammered at under all conditions. Since the steel maker had faith in the new metal and, what was more to the point, had his money invested in the venture, he tried to please the boiler-maker by making a very soft steel which the latter could, accord- ing to an expression heard once by the writer, ‘‘ be easily hammered into acocked hat.” Thus tke boiler-maker, who knew nothing as to the quality of the metal, actually decided on the standard of steel THE IRON AGE. to be used for boilers. Being used tc working iron, the boiler-maker expected to find the same qualities in soft steel, and being disappointed, the steel-maker simply complied with the law of adaptation to circumstances when he gave the boiler- maker as soft a metal as was wanted. steel-maker who best succeeded doing so made a fortune. Unfortunately this excessive softness of the steel was often bought dearly at the expense of wearing quality. Hence disap- pointment with the steam user, the reasons for which, however, were, like in many similar instances, ascribed to everything else but the right cause. Only expensive experience had to work out a solution of the problem. STEEL MADE TOO SOFT. It seemed that it was not so much the excessive softness of the metal which caused disappointment as the want of homogeneity which seemed to be a neces- | sary accompaniment of the softest grades of steel. Other parties better familiar with the qualities of steel committed the error of going too far in the opposite direction and advocated steel for boilers, which proved entirely too hard for the purpose, and thus worked into the hands of the soft-steel men. Some of this steel, which at first was brought from England, was so | hard as to cause the breaking of the plates when accidentally dropped on the rails on unloading or cracking while center- punching. One mancame near being par- boiled while calking up a fine crack in- side a fire-box. All at once the sheet at his back cracked from top to bottom and | the hot water began to pour over him. Since the calker did not stop long enough to examine into the causes of these | phenomena, it was simply set down as ‘*mysterious.”” The reason why one grade of steel was chiefly used and is still used largely, with a few notable exceptions, for tire-box and shell has had much to do with retarding a more definite knowledge of the causes of deterioration of boilers, and the matter was by no means simplified by the fact that even where a distinction is made between fire-box and flange steel no pains are taken to see to it that a differ- ence of quality really exists, FIRE-BOX AND FLANGE STEEL. The writer could never comprehend what use there is in specifying or asking for fire-box steel when the same price is paid for flange steel, and both grades have the same chemical consistency, give the same results as to tensile strength and elongation and have a structure alike in every particular. The forces which tend to destroy the material of which a steam- boiler composed certainly act with greater intensity in the fire-box than in the rest of the boilerif the latter is of the ordinary wagon or locomotive type, which forms the bulk of the boilers made. If, then, no distinction is made in grade of steel for fire-box and shell, the wearing qualities of the metal are judged by that portion of the boiler which has to stand the hardest wear. A great deal of the confusion about the qualities of stee! for boilers is due to the error of not considering the relation of the forces acting on the metal in a boiler to the qualities of the metal. In other words, is to the intensity of wear and tear it is subjected to in different parts of a boiler. Softness in the steel was the measure of quality, and unless a master mechanic or superintendent knew a good deal more of steel than the boileremaker he could not | long resist the warnings of the foreman boiler-maker that they were getting dan- gerous metal because it worked stiffer than ‘‘that other fellow’s steel.” If un- derstood and properly interpreted, that would probably kave meant a more homo- The | 7 aa l | wearing qualities of 993 geneous and therefore more reliable and cheaper metal than ‘‘ the other fellow’s metal. CHEMICAL COMPOSITION. One other reason why we are not yet in possession of that thorough knowledge of steel for boilers which we ought to have is probably that for awhile too much reliance was placed on chemical composition. The causes which led to failure and disappointment here and there were thought to be explain- able by chemical formula, while the struct ure of the material, homogeneity, uniform- ity, density and the effects of mill treatment were considered of secondary importance, if of any importance at all. |The feeble voice of the physicist was drowned in the mighty roar of the analyt ical batteries. | While it is not claimed that chemical composition is of no consequence—in fact, the steel-maker has to start with a given | chemical formula if his work is to amount to anything—yet the fact remains that sxb- sequent furnace manipulations, mill, shop and boiler treatment, may so alter or mask the influences of the original chemical composition that it seems to be quite futile to start out with ap imaginary normal | chemical composition for boiler steel as a | basis for the most desirable physical quali- |ties. We know that certain elements are injurious, and therefore it is advisable to keep them as low as possible; but how far the injurious effects of these elements are | modified or enhanced by the presence and proportions of other elements seems not yet decided. The effect of an excess present of a given element we can clearly perceive and are quite able to prove by | deduction and reasoning, but to ascribe all the effects of destruction of the metal com- | posing a boiler to the influence of a mi- nute proportion of a given element until that boiler goes to the scrap-heap seems to require a good deal of faith. Experience under varying conditions, careful investi- gation and comparison of different makes of steel, of cause and effect, have demon- strated that homogeneity and uniformity are main requisites for good boiler-plate. HOMOGENEITY IN STEEL. These two essential qualities do not | necessarily go together. A steel plate may be homogeneous but irregular in its structure ; harder and denser in one place |}than in another. But non-homogeneous | steel is also lacking in uniformity, since it | is not probable that the blow-holes in the | ingot caused by occluded gases are so uni- |formly distributed over and through the mass of the steel as to make the resulting sheet uniformly laminated through its length and breadth. Consequently the | break in the continuity of structure in the metal on account of the laminations caused | by flattening out of the original blow-holes in the ingot is not the same everywhere. Such a steel plate is not only not homoge- neous, but also not uniform. Want of homogeneity in a steel plate escapes de- tection more easily than want of uniform- |ity. A hard spot or hard portion ina sheet quickly attracts the attention of the boiler-maker because it requires a greater |expenditure of muscular force to work | that hard spot than the rest of the sheet. On the contrary, a laminated steel plate } t , in |is worked and rolled more easily, and such the quality of the material is not adapted | material is, therefore, the delight of the flanger in the boiler-shop. It is just here | where much of the mischief came in by ! ; the boiler-maker practically deciding the quality of steel for boilers when that metal was first introduced. LAMINATED STEEL. The very natural demand by the boiler- maker for soft steel after having been used to the soft iron brought a metal into the market which, while it was soft, was also frequently very much laminated. ae oe ; 2 e , et -_ on Sree a fee - Loe & a . a ER ; ae Jug? see} a a: “se : ’ s iF gay! bab ; Bie) See ; 16 ib Bhiasd bi pi te 2 DR Pe eb ee i | BAGLE BMB e aa : —-~ aa ere 994 It does not matter how this was, whether due to a close and natural relation of soft steel and honey-combed ingots, to careless furnace work or too great economy on the part of the mill people. Suffice it to say that the cry for softness produced an evil which caused material loss and a good deal of vexation and friction. This state of affairs was made worse by the belief that because laminated a steel plate was similar in many respects to an iron plate, it necessarily possessed the same merit, without considering how different the structure is in iron and steel, even in the THE IRON AGE. December 26, 1889 close to permit the safe conclusion to be !pand more and remain expanded. Thus drawn that the causes which exert a|the steel is made spongy, with 4 possible detrimental effect in telegraph wire to the transmission of electricity act in a similar and perhaps more intensified man- ner in a laminated fire-box by retarding the easy and uninterrupted flow of heat. If this reasoning is correct, then we can readily comprehend why laminated steel sheets, particularly fire-box sheets, are short-lived and expensive at any price, and why the boiler-makers’ cry for soft steel and steel ‘‘as nearly alike as iron” re- sulted in a large crop of unsuitable though very soft kinds of the latter. The fact | not necessarily dangerous. material. The Fig. 1. was lost sight of that what was not ob- | jectionable in the one was detrimental to the other. The slag which remains in the iron tends to an arrangement of the me- tallic mass into layers or bundles of fibers which, however, in good iron are thor- oughly interwoven, thus forming a ropy mass. In steel there is no slag worth speaking of. Its structure is crystalline and remains crystalline, and the fibrous ap- pearance in soft steel is due to finer or coarser laminations, which are the result of the rolling flat of very small or large blow-holes, as the case may be. These laminations separate the individual crys- tals, thereby destroying the continuity and weakening the metal in proportion to the size and number of laminations. In the accompanying sketch is intended to render clearer why laminated steel-plates are objectionable for use in fire-boxes. Figs. land 2 represent transverse sec- tions of laminated and homogeneous steel. The heat-waves striking the inner side of the fire-box sheet are expected to | Fig. 2. metal in the fire-box wore out, cracked, burnt, pitted, before it got a chance to burst, and when it did burst once in a while it collapsed from premature old age without doing much damage. The sheets in the parts of the boiler outside of the fire-box suffered less because they are thicker and are not taxed so severely. EFFECT OF EXPANSION AND CONTRACTION, Impaired conductivity, however, is not the only reason why laminated sheets are objectionable. The movements due to ex- pansion and contraction in a fi re-box being frequent and variable, a metal whose con- quickly traverse through the metal, which | gives off or conducts the heat to the water | on the opposite side. The better the con- ductive power of the metal the more readily will the heat be conducted away, and the more uniformly will the metal it- self be heated in all its parts and over- heating or burning be more easily averted. On the other hand, if the sheet is| laminated the heat-waves are checked more or less in their flow; the laminations act somewhat like an air-space obstructing and diverting the heat. The whole phe- nomenon resembles the action of water in momentarily stopped and diverted to another direction. Recent experiments made with sound | and defective wire have proved that flaws and blow-holes in the wire retard the flow of electricity along the metal. The | tinuity of structure is more or less destroyed by laminations is naturally weaker, and | though it will give the required number of thousand pounds per square inch in the | testing-machine, a sufficient percentage of elongation and will please the friend of reduction of area to his heart’s content, | 'the close observer whois not bound by) | tradition will easily discover the defective | a ditch, which, striking an obstruction, is | | nature of laminated boiler-plates and act |accordingly. The writer has so often nated sheets, worn-out homogeneous sheets /and duplicates of the same steel plate laid |away when the boiler was built that he | is satisfied that even if allowance be made measured, the thickness of worn-out lami- | liability to absorb the injurious gases from the fuel. The uniformity of a steel plate in its texture and strength may be im- paired through unequal distribution through the mass of the steel of the chemical elements gathering in larger proportions in one place than in another. This causes a portion of a plate to be harder than the rest. Unequal cooling and local pressure by hammering and failure to remove this source of inequality by subsequent careful annealing are also frequent causes of a want of uniformity which is objectionable and, under the in- fluence of unfavorable circumstances, may become decidedly injurious. Let us take, for instance, a combination of circum- istances like a segregated ingot, an over- heated slab, an unequally cooled plate, a |sheet tortured in flanging and an igno- |rantly-treated boiler, and surely nobody |need wonder if somebody goes to heaven with a wonderful velocity. Whoever is familiar with mill and boiler-shop prac- tice and the firing of boilers through- out the land will admit that such combi- nations are frequent and are a natural | consequence of the indiscriminate demand |for cheap material and want of thorough knowledge of the material used. | Nothing could be a better and more ‘convincing proof than this fact of the | fitness and reliability of steel for boilers | than the fact that so extremely few accidents | have happened to those who have now | been using steel for 25 years. It may be said that this is the reason | why a distinction should be made, not only in name, but in every-day practice, between fire-box and flange or shell plates. |The fire-box has to stand the greatest |amount of wear and tear and ought to be | built of material possessing, in addition to the requisite strength and ductility, homo- geneity and uniformity of structure to the highest degree. Only when once a ju- dicious discrimination is made in the metal used for those parts in the boiler which are subject to direct contact with the fire and those which are not will the buiiding of steel boilers have reached a satisfactory basis. Why this should beso we can com- prehend all the more easily when we con- sider that in an ordinary flange-plate the difference in strength and elongation in different portions of the sheet may vary from 4000 to 7000 pounds per square inch and 3 to 4 per cent. elongation in a 2-inch section, while in a fire-box plate which 1s tire-box steel not only in name, but is what it is represented to be, the variations are so slight as to be immaterial in every- day practice. A steel sheet which varies so much in strength and texture being held rigid by stay-bolts and rivets must be injured by the unequal expansion and contraction caused by the inequality of the structure of the metal in different parts. If we imagine the edge of a fire-box sheet in a horizontal position before our eyes while under the influence of the forces causing contraction and expansion, then we would | not be surprised to find the edge of a sheet analogy between the phenomena of heat | for variation in thickness of sheets due to! which is wanting in homogeneity and uni- motion and electric motion is sufficiently | springing of the rolls laminated sheets ex-!| formity assuming a wave-like motion, December 26, 1889 while on the other hand a first-class fire-box sheet would present a continuous straigh line. TESTS AS GUIDES. This state of affairs may be still more aggravated by unequal firing and other circumstances. The question will be raised to what extent tensile strength and elongation as expressed in a simple ten- sile test are guides as to quality and fitness of the material we wish to use. In the absence of a uniform standard test- section, different sections giving results differing from each other in values ex- pressed, the results ot every-day experience become incomparable, and therefore no definite answer can be given to the ques- tion asked. The longer the test-section, or in other words the more metal we allow to take part in the work of resisting the external force which tends to separate the particles of which the metal is com- posed, the lower the results in our test expressed in so many thousand pounds per square inch and per cent. of elongation. Hence the engineer who uses a straight section will differ in opinion from his brother engineer who uses the groove section as to the value of a metal in every- day practice expressed in pounds per square inch, unless the ratio of difference between these two sections is a fixed and invariable quantity. Unfortunately it is not, since every-day testing is not and can- not be done with such scientific accuracy as to become a basis for the determination of such important data, nor is the quality of materials even of the same class so in- variable as to be the same from day to day or from menth to month. Hence, however definite the experience of one engineer may be in regard to the value of a material expressed in the results of a tensile test, such experience is only valu- able when considered in connection with the particular test-section used by that engineer. Thus if one says 79,000 pounds per square inch 1s not too high while an- other may say that he found such high metal too hard, then such a statement has no value unless we know what section is used by each and what the difference is in value between the two sections plus the |steel he buys. errors 1n testing and the variability in | metal. THE QUALITY REQUIRED. With this understanding and a 2-inch section (between fillets) as a basis for measuring the value of materials in every- day or commercial testing, the writer is prepared to say that 55,000 pounds per square inch, with an elongation of not less than 30 per cent. per inch, should be the lower limit for flange steel and 60,000 pounds per square inch, with 30 per cent. elongation, for fire-box steel. If the strength runs beyond 68,000 or 69,000 pounds the metal is rather hard, and while such material may be acceptable when holes are drilled and all sheets are carefully annealed in a special annealing furnace, under present conditions and practice the writer would hesitate to ac- cept steel higher than the above figures, even if the elongation is satisfactory, unless well versed in the history of the steel made. The writer, being familiar with the experience of a consumer of steel in immense quantities, believes that harder material wears better in boilers and gives better satisfaction. Whether this will be the experience if ever basic steel comes into use cannot now be said. The ideal boiler-metal is that which carries a given -load an indefinite number of times with- out deformation and will not rupture when subjected to bursting-pressure, but | expand until the boiler leaks at every seam and stay-bolt. THE NECESSITY FOR VIGILANCE. No doubt thé anxious boiler-maker will ask to what extent a tensile test is a THE IRON AGE. guarantee for quality and safety in the It is well for the boiler- maker and consumer of steel plates to bear in mind that no process by which articles for consumption are produced is perfect; neither are metallurgical proc- esses perfect and probably never will be except perhaps in laboratory ex- perimerts. The next best thing to do, then, to insure quality and safety is, after fulfilling those conditions of com- mercial dealing which are generally found to secure the desired end, the acquirement of the largest possible share of knowledge as to the qualities.cf iron and steel. Eternal vigilance is not only the price of liberty, but as well of safety in a steam-boiler. Only when eternal vigilance is exercised from the first charge of material into the furnace until the last shovelful of coal that goes into a boiler before it is ranged out of service has all been done to secure quality and safety; provided always such vigilance is aided by thorough knowledge of the materials dealt with. With a due appreciation of these primary requisites to a successful examination of the metals we use, it must be said that the results of a tensile test only partly give a proper insight into the qualities of the metal used. The test simply a record of strength, the limits of which have been previously determined as the factor of safety. At the same time, by allowing a wide range between the determined limits of strength, the imper- fections are recognized in metallurgical processes when carried on on a large scale. Homogeneity and uniformity cannot be properly determined by a tensile test, though there are some features accom- panying a tensile test which in a measure indicate these important qualities to the expert. To those who are not engaged every day in testing materials, do not continually handle large quantities of materials from a score of makers, and who have not the fa- cilities to make thorough investigations of the metal bought, a few hints must suffice to supplement the knowledge cained through a tensile test of the qua:ity of the steel bought. is A METHOD PROPOSED. The following simple method will, after a little practice, help the intelligent boiler- maker to ascertain something about the homogeneity and texture of a steel-plate: Take a piece of the metal—say 6 inches long and i4 or 2 inches wide—file off suf- ficient metal at the edges for about 2 inches in length to remove the hardening effects of the shears; bend the piece at the place where the hardened edge was removed and close the bend under the steam- hammer so that the surfaces of the metal are in close contact. If the metal does not show any cracks on the surface of bend, or perhaps only small cracks at the edges, due to the imperfect removal of the hardened edges, then the metal possesses a reliable degree of ductility, even if the tensile strength should have been 68,000 pounds to the square inch in a 2-inch sec- | tion, equivalent to about 66,000 or 65,000 pounds in an 8-inch or straight section. If the rounded surface of the bend shows shallow depressions, as though a rubber band were tightly drawn over an in- dented surface, then it is an indication that the metal is laminated. The reason for this phenomenon is the want of continuity of structure, which being more or less de- stroyed by the laminations when the metal | is so violently stretched as in bending double, portions of the interior metal can- not follow, their connection having been previously cut, They are left behind and the outer skin of the metal sinks into the vacant space thus created. Like in a calculation, we can apply a proof to this test by putting a piece of the same metal, from as near to the bend as the | 995 practicable, into the vise. Nick it across its face about ,!, inch with a cold-chisel, and bend the portion which extends above the jaws of the vise backward with a few quick blows, and then double the piece up. The fracture will be found studded with openings gaping apart. If a piece of metal the bent surface of which is fine and smooth is nicked and broken in the same manner the fracture will be finely granular or compact and silky. Metal with fine transverse cracks across the surface of the bend indicates a disturbed condition of the structure through overheating or other causes which impair quality. If broken in the vise such steel will be found to break off short, like porcelain, without any of the elastic reaction experienced in a sound piece of steel when breaking it in the manner described. The vise fracture of such steel is generally bright and often coarsely granular. In this connection it may be well to allude to the prevailing be- lief that soft steel may be broken fibrous or granular, according to the skill of the manipulator, as iron is broken in the same manner. The writer has tried to prove this by more than a thousand tests under all imaginable conditions, but has failed to produce a granular fracture after the metal is rolled down to a certain thick- ness. Again, metal found to be granu- lar, say, at 4 inch thickness could be made to break fibrous with but poor results. This statement, however, not apply to experiments*made on steels when warm. That is an entirely different subject. does MECHANICAL TREATMENT. in regard to the mechanical treatment of boiler-steel in the shop, 1t is well to avoid local hammering when _ cold. Though the steel will not get materially harder by so doing, yet the greater den- sity in structure caused by local pressure produces want of uniformity which, as pointed out before, is liable to become detrimental. Steel being stiffer than iron requires some coaxing and humering to get it into shape, and when it isin shape it ought to be thoroughly annealed in order to remove all irregularity of structure caused by local hammering or unequal cooling. The reason for the desirability of an- nealing steel plates after hammering, though their strength may not suffer there- by, lies in that peculiar phenomenon called the ‘‘flow of metal” or the ‘‘flow of solids.” When this flow begius under the expansive force of heat it is interrupted and checked at the denser portion, thus causing an inequality of movements with injurious consequences. Though the move- ments in any portion of the plate during expansion and contraction are extremely small and inequalities caused in these movements through the inequality of structure in the plate must be correspond- ingly small, yet the researches of Woehler and Bauschinger teach us that it is the frequent repetition of small stresses which fatigues the metal more than occasional excessive loads. It will be readily under- stood how injurious want of uniformity may become through additional strains imposed upon the metal at one portion of the plate more than at another. Out of this grow the beneficial effects of thorough an nealing, by restoring greatest uniformity. It seems hardly necessary, however, to an- neal sheets which have not been flanged, though the rivet-holes may have been punched. THE BEST HEAT. Care should be taken not to work steel while in that stage of heat called ‘‘ blue” }or ** black.” | The best steel is liable to come to grief | under such treatment, and many have been the vexations and misunderstandings be- wad a< 996 THE IRON AGE. December 26, 1889 tween producer and consumer on account of disobedience to or ignorance of this precau- . tionary rule. The reason for the ease with upon by Sir Edward Guinness. He has| of Cleveland, Ohio. The Cleveland station placed $1,250,000 in the hands of trustees | of the Cleveland Electric Light Company to be used for the purpose of building is driven by an engine arranged as shown . which steel is injured at that particular houses for the very poor, in which they/in the accompanying plan view, Fig. 1, stage of heat called ‘‘ black” or ‘‘ blue” is|may have cleanly and healthy homes. | which belts over a pulley on the main “¥ found in the change of structure the metal | Mr. Peabody sought to improve the| shaft, the dynamos being placed on the undergoes at that stage. When red-hot | dwellings of artisans. Sir Edward will| floor above. Each side of the driving- the molecules of the metal are in a state| make his attack upon the slums, in the| pulley is a 48-inch four-arm friction- of motion and expanded condition which | hope of relieving the most abject and | coupling, C C. This permits at the start allows the metal to be worked, shaped | wretched of the inhabitants of London | the cutting out of either half of the main and compressed, As the heat decreases |and Dublin. *Four-fifths of the money is | driving-shaft. The friction-clutch pulleys the molecules return to their natural | to be spent in London and the remainder} A A are 60 inches in diameter by 104 Ff position until the metal is cold. There|in Dublin. The donor appeals for assist-| inches face, while the pulleys B B are 74 Be’ must, therefore, be a stage where the/ance in his great task to other charitable |inches in diameter by 134 inches face. «hs, molecules of the steel are in a state of | persons; and his appeal, backed as it is | The first-mentioned pulleys run the are ma- AR, disassociation characterized by a want of | by such splendid performance, ought not | chines, while the others run the incan- he cohesion which makes the metal weak or | to be made in vain. |descent. The clutch-pulleys are all oper- ‘ies brittle, and this dangerous stage is the ee ated from the second or dynamo floor, oe point of blue or black heat. This is not Arrangement of Friction-Clutch while the clutch-couplings are operated an a theory or a fancy idea, but with, proper material and method can be proved | to the satisfaction of anybody by a prac- | tical experiment, as the writer has fre- | quently done. ally, as described above. 5. That it is best to leave to the prac-| tical experience and judgment of the steel-maker the decision as to the chemical composition of the steel. 6. And finally that steel can be worked as well and with as little danger to injury by the boiler-maker after some experience. ' o a shin = = enn CONCLUSIONS. | The conclusions to be drawn from the | rs foregoing are : ~ 1. That steel is an entirely safe and re- | @ liable material for steam-boilers and is pref- | > erable to iron because it combines equal | qualities with less cost. 3 2. That the material for fire-boxes | ai should be of the verv best quality, while | ae forthe rest of the boiler an inferior or) ~ flange grade answers the purpose. ; 3. That steel with less tensile strength | ‘ than 56,000 pounds per square inch and | i 28 per cent. elongation in a straight or 8-| — inch section is not desirable for fire-box | seme steel, nor should the strength run above | -” 67,000 pounds in that section without | hee assurance of the skill and reliability of | g the steel-maker. — 4. That a tensile test 1s a sufficient | e guarantee of quality if such a test is sup- | a plemented by a few simple trials occasion- | —— $$ Canal men demand that New York State shall construct its own elevators in co-operation with the canal commerce be- tween New York and Buffalo, in order to rescue the canal from *‘ railroad buzzards,” who are now in possession of the elevators and make extortionate charges for the same regardless of law. \ oa The plan of benefaction set on foot in Great Britain by the munificence of Mr. Peabody has been followed and improved Rt BR LF 4a ee Couplings and Pulleys. The value of fmetion-clutch couplings and pulleys is quickly being more widely ‘from the engine floor. It is evident from this that each dynamo may be run absolutely independent of all the others, and that when idle there is no work expended uselessly in driving either }e— —-—_ -—__ - 21 0 - Fig. 1.—Arrangement of Clutch-Pulleys and | Couplings in Electric-Light Stations. recognized. This is due principally to the saving in power in comparison with the old method of fast and loose pulleys, and also to the saving in wear and tear and the reduction in the number of moving parts. Perhaps the industry which has most clearly recognized and profited by the benetits to be derived from the use of triction-clutch pulleys and couplings is that supplying electric light. In the ordinary electric-light station the | conditions vary most materially from those found in the usual machine-shop. First, , the high speed, the widely-varying loads brought on the engine, the liability of in- stantly taking off a part or the whole load and the number of subdivisions in the driving-shaft operating the dynamos. These features have influenced to a large extent the adoption by the electric-light companies »f these appliances instead of the old method of fast and loose pulleys. To illustrate what may be considered a typical arrangement of an electric-light station provided, wherever thought needed, with friction-clutch couplings and pulleys, we show the accompanying drawings, which are taken from actual practice and were provided by the Hill Clutch Works, its belt or a loose pulley. Further than this, the dynamos on the upper floor are so arranged as regards the driviny-shaft that those which are most frequently used are placed nearest the driving-pulley. For instance, in the two incandescent machines one clutch-pulley is placed next the driv- ing-pulley, while the other is placed at the extreme opposite end, several arc ma- chines being in the intervening space. This permits the use of the incandescent /machine without driving any of the others, and also permits the use of five arc ma- chines wtibent driving any of the others. In this way there is no lost power con- sumed in driving idle parts. ’ | The arrangement of the Pine Bluff (Ark.) station of the Pine Bluff Water and Light Company 1s shown in the other two plan views. These were made by the same works to show the arrangement of the driving power. In the first (Fig. 2) there are three en- gines, arranged one, M, to belt to the main driving-shaft and the others, D D, couple direct to each end of the driving-shaft. The engine M belts over the pulleys H K, H be- ing acombination pulley and clutch-coup- |ling. These two pulleys are mounted on a sleeve through which the line shaft passes. | By this construction the engine M can be | disconnected or connected with the shaft by the clutch-coupling H. The end engines | D drive the shaft direct through the elutch- /couplings GG. The clutch-pulleys E E, |F F drive the dynamos, BB representing | a Thomson-Houston alternating and are, C | a dynamo to be put in should the plant de- ;mand it and A A a Westinghouse alternat- | Ing. | The second figure of the Pine Bluff sta- | tion shows the same arrangement as regards | the dynamos and clutch-pulleys operating ee but the two end engines instead of being coupled direct to the shaft are 7 December 26, 1889 THE IRON AGE. 997 belted, the connection being made by the|of the range have revealed only one other | combination pulley and clutch-couplings| group which is greater in value and ex-| GG. The connection of the center engine| tent. The Juragua Mines, then, were M with the driving-shaft is the same as| found to be satisfactory in every way, and that described in Fig. 1. Both of these I brought them to the attention of Mr. permit the cutting out of any one or two! Earnshaw, the Pennsylvania Steel Com- portation of materials and supplies for five years. As is well known, the Juragua Company have been in successful operation ever since and have grown each year more prosperous. Their shipments of ore have been as follows: Tons. MN 6 dawacetnawdadesuakaveaacedeeras 25,000 MERTha Sends dacavthessenecedenwaneaees 80,000 NR arc ahed el neadae cade ones .. 110,000 reais Pecbathi a Sanaala yin otra ee ; po EAS cinch eUAe a csasaccebousdar 775,000 It is reported that they are preparing to ship 500,000 tons during the coming year. The ore shipped is of absut the following average quality: Metallic iron, 62 per cent.; phosphorus, 0.03 per cent.; sul- phur, 0.30 per cent. The Juragua Mines are the only proper- | ties throughout the region that have been operated, but since their development many locations of more or less merit have been made. The Sigua, like the Juragua Mines, | were discovered and acquired from the | State by Don Francisco Batlle y Gené, now |of Barcelona, and no account of this re- | gion sh