Popular Science Monthly/Volume 38/December 1890/The Development of American Industries Since Columbus: Iron and Steel Industry I
|THE DEVELOPMENT OF AMERICAN INDUSTRIES SINCE COLUMBUS.|
I. EARLY STEPS IN IRON-MAKING.
By WILLIAM F. DURFEE, Engineer.
TO all familiar with the iron and steel industries of this country it will be manifest that the story of their technological development can not possibly be told exhaustively in a magazine article, whose length is scarcely sufficient for an adequate description of a single one of the larger mechanisms employed in working iron or steel at the present time. Therefore, all that will be attempted in these papers is such a description of the beginning, growth, and present state of the technology of these vulcanian industries as will enable non-professional readers to obtain an intelligent idea of the more important improvements in machinery and methods that have contributed to a progress which, by successive steps, albeit oftentimes short, slow, and uncertain, has brought these industries safely through the manifold perils of three hundred years to their present wonderful expansion. All authorities agree in the opinion that iron was unknown to the aboriginal inhabitants of America. Tools, weapons, ornaments, and culinary vessels made of copper were occasionally found in their possession, but nothing of iron.
The first mention of the existence of iron-ore on this continent was by Thomas Harriot, "the geographer" of the second expedition to Virginia. This expedition effected a settlement on Roanoke Island, and Harriot in his history of the colony says: "In two places of the countrey specially, one about foure score and the other six score miles from the fort or place where wee dwelt, wee founde neere the water side the ground to be rockie, which, by the triall of a minerall man was founde to hold iron richly. It is founde in manie places of the countrey else. I know nothing to the contrarie but that it maie bee allowed for a good marchantable commoditie, considering there the small charge for the labour and feeding of men; the infinite store of wood; the want of wood and the deerenesse thereof in England; and the necessity of balasting of shippes." Nothing seems to have come of this discovery; and the colony, being menaced by the Indians, became discouraged and returned to England in 1586.
We next read of American iron-ore in the history of the colony which located at Jamestown, Virginia, in 1607. We are told that "on the 10th of April, 1608, the company's ship sailed from Jamestown, loaded with iron ore, sassafras, cedar posts, and walnut boards." Seventeen tons of iron made from this ore in England was sold to the East India Company for £4 per ton. This was without doubt the first sale of iron made from American ores. An attempt was made in the years 1620 to 1622 to erect iron-works on Falling Creek, a branch of the James River, about sixty-six miles above Jamestown, but on the 10th of March, 1622, the buildings were burned by the Indians and 317 persons were killed; thus ending in fire and blood the first attempt to make iron on a manufacturing scale on this continent.
We have no account of the actual form of the furnaces or other apparatus, nor any description of the methods of smelting employed in the earliest iron-works of this country, but from the evidence accessible we are quite safe in assuming that the early American metallurgists were in no great degree wiser than their European instructors; and, when we consider the difficulties of every kind that must have surrounded all attempts to manufacture iron in a new country, it seems highly probable that our early iron masters would have adopted the simplest and most inexpensive methods known to be capable of accomplishing the desired result, and, as fuel and ore were abundant, it is not likely that economy would be much studied in their use.
The simplest process known for obtaining iron from its ore can be carried out in an ordinary blacksmith's fire by throwing crushed ore upon the ignited fuel, covering it with coal, and, after urging the fire with bellows for a considerable time, there will be found in the bottom of the fire an irregular mass of forgeable metal. Some form of this process is still employed by many savage and semi-civilized people; and this was doubtless the method used by the "mineral man" in testing the ores of iron discovered by the Roanoke colonists in 1585.
In Fig. 1 is shown a modification of this process, practiced by the iron-workers of Persia and adjacent countries, who have
Fig. 1.—Persian Method of Smelting Iron.
manufactured both iron and steel by this simple and inexpensive method (as measured by their standards of the value of time, labor, and material), from the days of Tubal-Cain to the present time, and have fabricated therefrom cutting tools and weapons of unsurpassed excellence. The keenness of edge, wonderful temper, and marvelous elasticity of the swords of Damascus have had a world-wide fame for thousands of years. George Thompson, the distinguished English orator and philanthropist, stated that when in Calcutta, he saw a man throw in the air a handful of floss silk, which a Hindoo cut in pieces with his saber. Many of the swords and daggers made in central and western Asia two thousand years ago were as remarkable for their elaborate finish and exquisite ornamentation as for their more practical qualities.
The process, illustrated by Fig. 1, was substantially as follows: A basin-shaped hole, six to twelve inches in depth and twelve to twenty-four inches in diameter, was first made in the earth; this cavity was then lined with moistened charcoal dust, which was well rammed to make it as dense as possible; the hearth thus formed was then filled with charcoal, on which was placed a layer of crushed ore, and over this alternate layers of fuel and ore until the heap was of the desired height; the outside of the mass of charcoal and ore was then incased in a covering of rough stones laid in a mortar of clay and sand, or, in some cases, it was merely plastered over with a thick layer of such mortar; care was always taken to have a hole near the bottom, just above the edge of the hearth, for the insertion of a tube of baked clay to serve as a tuyère, and a second hole at the top for the escape of smoke and gases. Fire was then introduced at the tuyere and the bellows connected; a gentle blast being used until all the moisture in the ore and the covering of the heap was driven off. As soon as this was accomplished, the blast was increased and the heat thereby augmented. At the end of several hours a mass of metallic iron, weighing twenty or thirty pounds, was found in the bottom of the hearth, from which it was removed by tongs and forged by sledge-hammers into the desired shape, several reheatings being required. The iron obtained was not usually over twenty per cent of that in the ore, and only the richest ores were used.
The first attempts to smelt iron-ore were probably made in open, or perhaps partially inclosed, fires, in which the operation was conducted without the stimulus of a blast; but the slow and very irregular burning of the fuel during calms, as compared with its more rapid and effective combustion when urged by a high wind, must have soon suggested the desirability of a regular and manageable method of supplying the primitive furnaces with a current of air, and we find that the use of some contrivance for this purpose is of great antiquity.
Bellows are known to have been used by the Egyptians over three thousand years ago. They consisted of a pair of leather bags (which were nearly spherical when inflated), to each of which was attached a tube for the discharge of the air. The operator stood with a foot on each of these bags, and pressed them alternately by throwing his weight from one foot to the other. In the top of each bag was a round hole, which could be closed by the foot of the workman, and a cord held in each hand enabled him to distend and inflate either bag as he compressed the other. His feet served as valves to prevent the escape of air from the holes, and compelled it to pass through the discharge-pipe into the fire.
Piston bellows were known in Egypt at least two thousand years ago, and compressed air was used for various purposes other than blowing fires. The kind of bellows shown in Fig. 1 was known and used by the Greeks and Romans at a very early period, and the bellows of our kitchens are of equal antiquity. Bellows constructed as shown in Figs. 3 and 15, were invented in Germany in the latter part of the sixteenth century; the exact date, as well as the inventor's name, is uncertain. Bellows working on the principle of those used in accordions and concertinas have also been known for many centuries. An engraving, showing such bellows in use blowing a furnace, is given in the great work of Agricola, who also illustated rotary fan-blowers; but these evidently did not propel the air centrifugally, as does the modern fan-blower, but pushed the air forward, very much as a revolving paddle-wheel pushes water.
Another very curious apparatus for blowing furnaces and smiths' fires is called a trompe. It consists of a vertical pipe, usually made of wood, of a length suited to the fall of water. Near the top of this pipe there are pierced a number of comparatively small lateral openings which incline downward in their passage through the thickness of the sides of the pipe, whose lower end enters the closed top of a barrel or other air-tight vessel, from which proceeds a tube to convey the air to the furnace or forge. This contrivance operates as follows: The descending column of water in the pipe draws in air through the lateral openings near its top, and this air is carried down by the water and separates from it in the interior of the barrel and then passes to the forge by the discharge-pipe, the water escaping through a hole at or near the bottom of the barrel. Percy, speaking of this very simple blowing apparatus, says, "It is said that it was invented in Italy in 1640." But it must have originated at a much earlier date, as Branca gives three applications of it, illustrated by engravings, and it is very probable that this highly ingenious method of employing the fall of water to compress air was known and used hundreds of years before the time of Branca.
The early American forges and furnaces were blown either by the ordinary leather bellows (Fig. 1), or by wooden cylinders called "blowing-tubs," or by the trompe just described, and there are still to be found in use a few examples of each of these primitive methods of "raising the wind." In Fig. 2 we have an illustration of a pair of "blowing-tubs" such as Overman describes as "the best form of wooden blast-machine." The figure shows a vertical section through the axes of the upright "blowingtubs," a a, and the "wind-chest," b, placed immediately above them. Air enters the tubs from beneath and is purnped by the pistons d d, with the aid of the "clack-valves" shown in the figure, into the windchest. The pressure of the air in the windchest is determined by the weight h suspended at the lower end of the rod attached to the piston g, which rises and falls as the volume of air beneath it varies in accordance with the demands of the furnace or the slight irregularities of supply. The air was conveyed to the furnace through a metal pipe, c, connected with the wooden bottom of the wind-chest by a flanged elbow. Blowing-tubs of a square cross-section with corresponding pistons
Fig. 2.—A Pair of Blowing-Tubs.
have been used with success, and as late as 1873 three such machines were in use in Detroit for furnishing blast to a large cupola; and, notwithstanding the primitive construction of this blowing apparatus, the melting was quite as satisfactory and economical as the best of the present day.
Having now described the various forms of apparatus for blowing furnaces and forges in use at the beginning of the seventeenth century, we will again turn our attention to the progress of the manufacture of iron in America. The first iron-works built in this country that are entitled to be called successful were erected in the Province of Massachusetts Bay, in what is now the town of Saugus, a suburb of the city of Lynn, about ten miles northeast of Boston. Their owners, "The Company of Undertakers for the Iron-works," were granted a number of special privileges, among which was the monopoly of the manufacture for twenty-one years. The works appear to have been commenced late in the year 1643 or in the beginning of 1644, and were nearly completed in 1645, as on the 14th day of May in that year the General Court passed a "Resolve," declaring that "ye iron-works is very successful (both in ye richness of ye ore and ye goodness of ye iron)," and that "ye furnace is built, with that which belongeth to it, . . . and some tuns of so we iron cast . . . in readiness for ye forge." On the 14th of October of that year the General Court granted still further privileges on the condition "that the inhabitants of this jurisdiction be furnished with barr iron of all sorts for their use, not exceeding twentye pounds per tunn," and that the land already granted be used "for the building and seting up of six forges, or furnaces, and not bloomaries onely," and the company was confirmed in the right to the free use of all materials "for making or moulding any manner of gunnes, potts, and all other cast-iron ware."
On the 6th of May, 1646, Richard Leader, the general agent of the company, purchased "some of the country's gunnes to melt over at the foundery." This statement seems to justify the belief that there may have been a reverberatory furnace in this "foundery," as such furnaces were well known in Europe at that date, and castings of all sorts were made from metal melted in them; but it is certain that, at the same period, castings were frequently made from iron taken direct from the blast-furnace, and we know that scrap cast iron can be melted in a blast-furnace without difficulty. The cupola furnace, for remelting "pig iron" and scrap cast iron, was not invented until 1790, and, consequently, we are sure that it was not employed in the "foundery" at Lynn in 1646. Hence it is evident that the "gunnes" purchased must have been remelted in the "blast-furnace," or in a reverberatory furnace, although we have no decisive evidence of the employment of the latter type of furnace.
It is certain that at Lynn, in the Province of Massachusetts Bay, was cast, in the year 1645, the first piece of hollow ware made in America—"a small iron pot capable of containing about one quart." This pioneer of all American-made castings was in existence in 1844, but recent efforts to ascertain its whereabouts have been unsuccessful. The works at Lynn appear to have been very prosperous for a number of years; but after a time they became unpopular, owing to the flowage of lands by their dam, and the great destruction of timber for fuel.
The Rev. William Hubbard, writing in 1677, says they were "strenuously carried on for some time, but at length, instead of drawing out bars of iron for the country's use, there was hammered out nothing but contentions and lawsuits." Just about this time Samuel Butler was writing his great poem in which he makes Hudibras say:
Alas! what perils do environ
The man who meddles with cold iron!—
a reflection which has been sadly appropriate in the case of too many American iron-works.
After the establishment of this first successful "furnace" and "foundery" at Lynn, works for the manufacture of iron were erected in other parts of New England, and thence-the business spread into New York, New Jersey, Pennsylvania, and Maryland. During the "French War" (1755) there were a number of furnaces in operation at which "cannon, bombs, and bullets" were made in great quantity, and many of these iron-works furnished similar supplies to the Continental army during the Revolution.
It is a matter of profound regret that no drawings of the early iron-works erected in this country have been preserved; and we are therefore compelled to form our ideas of their construction from such meager verbal descriptions as are given by writers of the time, combined with illustrations of furnaces and processes for the manufacture of iron known to have been used at or near the same period in Europe. The iron-works at Lynn seem to have embraced a "blast-furnace," a "foundry," and a forge. The product of the furnace was in part made into "so we iron," and the remainder used in "ye foundery," for the manufacture of hollow ware and other castings. In "ye forge," the sow iron was converted into "all sorts of barr iron." The blast-furnaces in use in Germany at that time were from twenty to twenty-five feet high, and had boshes, and openings at several heights for the purpose of tapping out the cinder. In the Philosophical Transactions for 1676, Henry Powle, describing the furnaces then in operation in the Forest of Dean, in Gloucestershire, England, says: "The blast-furnaces are about twenty-four feet square on the outside, nearly thirty feet high, and eight or ten feet wide at the boshes. Behind the furnace are placed two huge pair of bellows, whose noses meet at a little hole near the bottom. These are compressed together by certain buttons, placed on the axis of a very large wheel, which is turn'd about by water in the manner of an overshot mill. As soon as these buttons are slid off, the bellows are raised again by the counter-poise of weights, whereby they are made to play alternately, the one giving its blast all the time the other is rising."
Fig. 3 is a vertical section of a blast-furnace, such as had been used for some years in Sweden prior to 1734; and it may be regarded as representative of the construction of furnace that had been employed in Germany, France, and England for the previous hundred years, and in all probability for a much longer period. The reader will readily perceive that the bellows (made of wood) were operated by what Henry Powle, above quoted, described as "certain buttons"; and in fact the construction and size of the furnace illustrated did not differ greatly from that seen by Powle. This Swedish furnace was fifteen feet square outside, and twenty-nine feet high; its internal diameter at the top, D D, was four feet, and at the widest part six feet. The "boshes," or diminishing part of the furnace, O O, were made of a mixture of fire-clay and crushed quartz; the inner walls, M M, were of sandstone laid in regular courses, while the outer walls, G G, were made of any convenient coarse, rough stone laid in lime mortar; the space, F F, between the inner and outer walls, was filled with cinder, small stones, and other similar material. The hearth, C, was about two feet square. The top of the furnace was surmounted by a parapet, H, of rough-hewn logs. Comparing the construction of this furnace with the earlier practice, Swedenborg says:
"Formerly furnaces were constructed much simpler, and no specific or exact proportions were observed; and it was not considered necessary that the walls should have any fixed dimensions, either as to thickness or height; but (according to Agricola, who was the first to describe them) the whole structure was rude,
Fig. 4.—A Reverbatory furnace, (1647.)
loose, and imperfect, their daily product of iron was small, and they consumed a very large quantity of charcoal; but afterward, when it became evident that regularity in smelting insured excellence of product, and at the same time the realization of greater profit, then more perfect plans were made, and higher furnaces, having greater capacity and more solid walls, were constructed."
The reverberatory furnace had been employed in Europe from the earliest times for the melting of brass and other metals; and for heating them dry wood was the usual fuel. Benvenuto Cellini (about 1547) erected such a furnace for melting the bronze for his statue of Perseus; and he expressly states that he commenced the melting with "pine wood, which, because of the oiliness of the resinous matter that oozes from the pine tree, and that my furnace was admirably well made, burned at such a rate, that I was continually obliged to run to and fro, which greatly fatigued me"; and, after describing various troubles in getting the metal melted, he finally completes that operation by the use of "a load of young oak, which had been above a year in drying."
From a French work on the construction of artillery we take Fig. 4, which is a very spirited illustration of a reverberatory furnace at the moment when the metal is being tapped into the molds. In this figure A is the furnace; B, the furnace-doors, which are made of iron; C, chimneys of the furnace; D, firehole; E, frame of carpentry above the pit, to which is attached the pulleys and other tackle which serve to lower the molds into the pit and remove the castings made; F, pit (made in the earth), in which the molds are placed; G, "runners" with "gates" for the metal; H, workmen who split the wood and carry it to the furnace; I, workman who throws the wood into the fire: the wood falls upon a grate which is at the bottom of the fire-box, three feet or more below the part of the furnace containing the metal; K, cover, or paddle of iron, for closing the mouth of the fire-box; L, workmen who raise the furnace-doors by means of a lever; M, lever for raising furnace-doors; N, workmen who stir the melted metal with poles of wood, and who remove the slag and refuse metal with tools called "rabbles"; O, the master founder, with the tapping-bar, opening the hole by which the metal is discharged into the "runners"; around him stand a group of interested visitors. After this description we are told that "the furnace at Douay contains sixty thousand pounds of metal." This would not be regarded as a small furnace even now.
As illustrating how the metal was taken from the early blastfurnaces for the making of "sowe iron" and castings of various kinds, we reproduce Figs. 5 and 6. In Fig. 5 workmen, numbered 1 and 2, are seen making an open mold of triangular crosssection in the floor of the "foundry," in which is to be cast a sow, and others (3 and 4) are removing, by means of levers and rollers, the sow last made. The wooden bellows which blow the furnace are shown at R, R, R. The furnace illustrated appears to have been constructed with unusual care, its walls having been
Fig. 5.—Preparing to cast a sow.
built of dressed stone laid in regular courses, strengthened at the corners by massive rampant arched buttresses, one of which is marked Z, Z. At B, B, B, are iron bearers that support the masonry of the furnace above the arch; C, C, are side stones of the hearth; D is the "tymp"; F, the "dam"; I, the "tap-hole."
In Fig. 6 we have a view of the interior of an ancient "foundry," in which the metal was taken direct from the blast-furnace and used for the making of castings. In this engraving a workman (1) is taking the metal from the hearth of the furnace over the dam F, with a ladle. Another workman (3) is "pouring" the
Fig. 6.—Interior of an Ancient Foundry.
mold c, with metal from a hand-ladle; while a boy (4) skims the metal and prevents slag and other floating impurities from escaping with the metal from the ladle; close at hand is another mold, b, ready for pouring. At 5 is a man pouring metal from a hand-ladle into the "gate," Z, of a mold that is buried in the floor of the "foundry" while a second man (6) keeps him supplied with metal from another ladle which is skimmed by a boy (7). At 8 is a man cleaning a cast-iron pipe. Pipes made at this period were rarely over three feet in length, and were provided with polygonal flanges at each end for fastening them together with bolts. Pipes two inches in diameter had oval flanges and two bolts; three inch pipes had triangular flanges; eight-inch pipes were square-flanged; while pipes of twelve and eighteen inches in diameter had flanges of six and eight sides respectively, the number of bolts always equaling the number of angles in the flanges.
It is not at all certain when the first castings were made from remelted sow, or other form of crude cast iron; but the crucible has been used for remelting cast iron since a very remote period, and is largely employed in China for that purpose at the present
Fig. 7.—The Process of Casting Crucible-melted Iron.
day, and the culinary utensils made in that country are remarkable for their thinness. As illustrating the making of castings from crucible-melted iron, we extract Fig. 7, from Réaumur's work. In this plate "b is a shed, under which is placed a furnace c, such as is ordinarily found in the shops of the makers of small castings. This furnace was blown by bellows, held but one crucible, and was quite similar in construction to many furnaces in use at the present day; d d is a box for holding the molding-sand; e e are molds being dried. At the left is seen a small portable furnace on wheels, to which blast is supplied by the bellows h, of a forge. When this is used as a forge, the bellows h are rearranged so as to blow through an opening at the top. In the figure, 2 is a workman filling a mold with fluid metal which has been melted in the furnace. At m are seen the screw-clamps that confine the three molds n. Near the middle of the picture are two parts of a mold separated; at the right, in the foreground, is a pile of charcoal, and at q is a furnace (similar to a baker's oven) for drying the cores for the molds."
Fig. 8.—Melting Iron for Casting in Small Furnaces.
In Fig. 8 (also taken from Reaumur's treatise) "is shown two common furnaces in which the iron to be melted is thrown among the charcoal without being placed by itself in a crucible; one of these furnaces is represented as erected, and actually melting the iron; while the other is dismounted, and the melted iron is being poured into molds. "The workmen (1 and 2) operate the bellows; a b is the upper part of the furnace, whose base is buried in charcoal dust; b is the opening into which is thrown the charcoal and pieces of iron; c c, the powdered charcoal which surrounds the base of the furnace; d is the tuyère which receives the noses of the bellows; e is a heap of charcoal; e 2 is a pile of fragments of cast iron; f is a post which supports the lever g, by means of which the ladle which forms the bottom of the furnace is easily raised." The workmen (3 and 4) are occupied in pouring into molds the iron which has been melted in the second furnace, which, is exactly like that already described; 3 is manoeuvring the lever, to one end of which the ladle containing the melted iron is suspended; 4 holds the handle and tips the ladle, thus regulating the pouring of the metal; i i, the hole from which the ladle k, forming the base of the second furnace, was taken for pouring; l, the upper part of the furnace removed; n, mold in which the iron is being poured."
Réaumur also describes a third apparatus for melting cast iron, which consists of a furnace of similar form to that just described, but without the removable ladle bottom. This furnace was supported on "trunnions" by a carriage mounted on wheels; at a proper height above the bottom was a "tap-hole," and on the opposite side an opening, or tuyère, for the nose of the bellows. The iron to be melted was (as in the last furnace) mixed directly with the fuel, and when it became fluid accumulated in the bottom of the furnace; as soon as all the iron was melted, the "taphole" was opened and the bellows removed; the whole body of the furnace was then turned on its "trunnions," and the metal run off through the "tap-hole" into "molds" placed to receive it. This furnace was at a later period called a "calabash," and it may be regarded as the direct progenitor of the modern foundry "cupola"; and it is not more than forty years since a very similar apparatus was in use in this country for melting brass; but in this the furnace, after the metal was melted, was suspended by its "trunnions" to a crane, and, being without a "tap-hole," the metal was run into the molds by inclining the furnace sufficiently to allow it to run over the top.
The reader must not infer that the primitive lever crane, illustrated in Fig. 8, was the only form known in the early part of the last century; as, on the contrary, Agricola, more than one hundred and fifty years before, described and illustrated several cranes of much more elaborate construction, some of which are quite similar in idea to foundry cranes in common use at the present day.
As in some degree illustrative of the rude picturesqueness of all the belongings of the old type of charcoal furnace, we have engraved (Fig. 9) a view of the remains of one situated on the Conemaugh River, in western Pennsylvania. The "hot-blast stove" which surmounts the "stack" is evidence that the spirit of modern progress has wrestled with the inevitable in vain, and the broken "blast-pipes," grass-grown "stack," and luxuriant surrounding vegetation, show that the breath of igneous life has passed away forever, and that Nature is claiming her own again.
The old colonial iron-works were of necessity located in valleys where advantage could be taken of a natural fall of water, or where a stream could be dammed at small expense; and, although when measured by the standards of our time, they were very imperfect in plan, rude in structure, uncouth and clumsy as to machinery, yet these primitive works produced metal, albeit small in quantity (eight to ten tons per week), of a quality that has never been excelled by the colossal furnaces and forges of this day and generation. The progress of improvement in those early days was slow, painful, and uncertain. Steam and Electricity, twin sons of modern civilization, were unborn, and the mechanic arts only represented what was possible to be accomplished by
Fig. 9.—Old Furnace on the Conemaugh.
the skill and muscular energy of men and animals. The wonder-working mechanisms now known as "machine-tools" were unimagined, and men wrought laboriously, by dint of the acute eye, cunning hand, strong arm, and stalwart courage, at subduing the savagery of a continent.
In presence of so many obstacles, and having such plentiful lack of nearly everything that modern engineers and artisans would regard as indispensable, the failure of the pioneer American sons of Vulcan would have occasioned no surprise, and their triumphant success is therefore all the greater wonder.
Thus far we have spoken chiefly of the furnaces and apparatus used in colonial times for the production of cast iron in its three forms of "sowe iron," "pig iron," and "castings," and have briefly alluded to the fact that the earliest known method of obtaining iron from its ores produced a forgeable and weldable metal. We now purpose to describe more fully this primitive process, and to illustrate some of the machinery by which the iron produced was wrought into bars of various sizes and forms. The process illustrated by Fig. 1 (page 147) is with slight modifications still in use in Africa, and from iron produced in this rude way the native Kaffir blacksmiths forge the heads of such "assagais" or spears as were used with deadly effect in the last conflict of the Zulus with England.
The quantity of iron that can be obtained by this simple process as the result of a single operation is quite limited and only sufficient for the forging of implements of very moderate size; but, as mankind gradually improved the conditions of life, the necessity for larger masses of the most potential metallic factor of civilization became more and more urgent, and to meet this demand there was revealed to some receptive and executive intelligence among men the means by which such larger masses of iron could be obtained, and the "Catalan forge" or "blomary fire" supplied for a time the world's needs for an improved process of manufacturing wrought iron. A section of one of these "forges" or "blomary fires" is represented by Fig. 10. The cavity of the hearth d, in the earlier forges, was lined with fire-resisting scone (usually some variety of sandstone); but later, fire-bricks were used, and still later, iron plates, which in the more recent "blomaries" have been made hollow and kept cool by a circulation of water. The tuyère, b, was placed from seven to eight inches above the bottom of the hearth, and was contrived so that its inclination could be varied at pleasure. The blast was produced
either by the "trompe" or by wooden or leather bellows; and sometimes by what some writers—in utter defiance of Euclid and all his disciples—have called "square wooden cylinders," worked by rude water-wheels.
The ores most frequently reduced in these "blomary fires" were the rich magnetites containing about seventy per cent of iron, although poorer ores could be, and oftentimes were, used. Sometimes the ore was employed in the "raw state" (i. e., just as
Fig. 10.—A Blomary Fire.
it is taken from the mine), but the best practice was to subject it to a preliminary roasting in heaps. The operation of smelting the ore, or more properly deoxidizing it (for the metallic iron obtained in these "fires" was not the result of a true fusion), was substantially as follows, viz.: The bottom and sides of the "hearth" having been lined with a thick coating of charcoal dust, it was then filled with charcoal, upon which crushed ore was thrown, and kept in place by a dam of charcoal dust (c, Fig. 10). The fire was blown gently at first, and as the heat increased a more powerful blast was employed; ore and coal were added from time to time as the work progressed, and sometimes the mass of fuel and ore was heaped up three or four feet. After an hour and a half or two hours of blowing, most of the iron in the ore was found in a pasty condition at the bottom of the hearth, in a bath of liquid "cinder" formed from the impurities of the ore and the ashes of the fuel; the blast was then augmented and most of the "cinder" drawn off through a "tap-hole" in the front side of the hearth, after which the pasty iron was lifted by bars until it was opposite or somewhat above the tuyère, and was there heated and manipulated until it became a spongy but coherent mass or "ball" of forgeable iron, twelve or fifteen inches in diameter, whose numerous
Fig. 11.—Removing a Ball from a Catalan Forge.
cavities were filled with a more or less fluid cinder. For the purpose of expelling this "cinder" and imparting greater density and coherence to the iron, the ball was then removed from the fire (Fig. 11) and taken to a "trip-hammer" (Fig. 12) and "shingled."
The resulting "bloom," roughly cylindrical or rectangular in shape, represented about three fourths of the iron contained in the ore used; the remainder went into the cinder and was lost. The weight of the "bloom" obtained at a single operation was usually from three hundred to three hundred and fifty pounds.
The simplicity and consequent cheapness of construction of the blomary fires caused them to be largely employed in the early years of the iron manufacture in America; and a few, that have superior advantages for obtaining supplies of ore and fuel, remain active at the present time. We are told that in 1731 there were in all New England "six furnaces for hollow ware and nineteen forges or blomaries for bar iron. At that time there were no furnaces for pig iron exclusively nor any refineries of pig metal; there was one slitting-mill and a manufacture of nails." In that year there were no iron-works in New York, and but a few in New Jersey (one furnace and "several forges"); in Pennsylvania there were one furnace and three "forges." At the same time there were two "furnaces" and one "blomary" in Delaware, and two "furnaces" and two "blomaries" in Maryland, and in Virginia there were three "blast-furnaces" and one "air furnace" (a form of reverberatory furnace), "but no forge." The fifteen "furnaces" and thirty "blomaries" above enumerated represented the growth of the iron industry of America during the eighty-six years following its birth at Lynn.
As the result of a superabundance of painful pondering, supplemented by a proportional volume of conservative hesitation and doubt, the manufacture of iron slowly increased, not only in America, but in the world at large; and soon after the "blomary process" had been generally recognized as the most satisfactory method of making iron, the growing needs of expanding civilization began to demand some means by which the more abundant ores that were not so rich in iron as those required by the "blomary fires" could be easily and cheaply smelted, and at the same time furnish larger masses of forgeable metal than the process in common use could supply.
This demand led to the invention of the "Osmund furnace" and the "Stücköfen." Both of these furnaces are of German origin, but it is not absolutely certain which is the older; for, although we hear of the "Stücköfen" as early as the year 1000, we find no mention of the "Osmund furnace" (by that name) until early in the eighteenth century, though furnaces of similar size and construction (called "Blaseofen" and Bauernofen) had been in use in Germany for several hundred years; and as the natural course of development of all mechanisms and apparatus is from the smaller to the larger, or from the less to the more efficient, it is extremely probable that the "Osmund furnace" was the immediate successor of the "blomary" and that the "Stücköfen" (a much larger and loftier construction) followed pretty closely in point of time after it.
Fig. 13.—An Osmund Furnace.
The general construction and equipment of an "Osmund furnace" are represented in Fig. 13. This engraving is a copy of one given by Percy as a reproduction of a drawing accompanying a report of a Swedish mining surveyor to the Royal Board of Iron Trade in 1732. A similar engraving (but three times the size) is contained in the work of Swedenborg, who gives in addition a vertical section of the furnace, which is also copied by Percy, and which we present in Fig. 14.
In Fig. 13, A is a heap of uncalcined bog-ore; B, a calcining fire of wood on which the ore is "roasted"; C, a heap of calcined bog-ore; D, earth-borer, used to search for ores; E, charcoal-rake; F, iron shovel; G, tongs for drawing the "bloom" from the hearth of the furnace; H, cinder-hook, also used in handling the bloom; K, bar, used for clearing the cinder-notch and tuyère; L, large sledge for hammering the "bloom"; MM, the lump of iron; N, the hatchet; O, the treadles for working the bellows; P, bridge of planks; Q, tap-hole for cinder; R, tuyère; S, wooden shovel for filling ore into the furnace. It will be noticed that the
Fig. 14.—Vertical Section of an Osmund Furnace.
masonry of the furnace is incased by timber-work, which is locked together at the angles. This construction, rude and unsatisfactory as it appears to eyes familiar with the iron-bound furnace-stacks of the present day, was a not uncommon one as applied to the earlier blast-furnaces in this country; and those in which it was employed were called "log-furnaces," to distinguish them from furnaces whose exterior walls were entirely of masonry. The bellows, in the case of the Osmund furnace illustrated, appear to have been operated by a woman, who, by stepping first on one of the treadles and then on the other, thus raised by her weight the bellows boards alternately; while at the same time her nimble fingers were busy with distaff and spindle. We think we are entirely safe in saying that this method of blowing a furnace was never employed in America.
It is not certain that the Osmund furnace was ever used in this country, as we find no mention of any furnace having been erected called by that name; but, when we consider its simplicity and consequent cheapness of construction, and that it was (according to Swedenborg especially adapted to the working of bog-ores, large quantities of which were actually smelted in New England, it does not seem at all improbable that furnaces of similar form may have been used there for smelting such ores; and the fact that this furnace produced wrought iron in masses of considerable weight would make it of especial utility in connection with forges, which were quite numerous in the New England colonies at the beginning of the eighteenth century.
The Stücköfen was an enlargement upward of the Osmund furnace, and may be pretty accurately described, as one Osmund furnace inverted upon another, its interior form being that of two cones united at their bases, a hearth similar to that of an Osmund furnace being formed at the lower part. We have no certain information that the Stücköfen was ever used in this country; but as this furnace was well known in Europe, where it had been in use for several centuries, those interested in the earlier smelting enterprises in the American colonies must have been acquainted with its construction, and it is very probable that some of the earlier blast-furnaces were Stücköfens under another name. The fact that this furnace could be so worked as to produce either cast or wrought iron, as desired, would make it especially valuable in a new country, where there was not sufficient demand for either metal to keep a furnace constantly employed. Besides those already enumerated, there was another method of producing a "bloom" of forgeable iron; viz., by the remelting of "sowe" or "pig" iron in a "Catalan forge" or "blomary fire." In colonial times this operation was largely used and was often described as "refining," and the premises in which it was carried on were frequently called a "refinery"; but the reader must not conf ound this term with that applied to a comparatively modern apparatus of quite different construction and purpose, which we will describe later.
This old refining process consisted substantially of melting the pig iron with charcoal, and then directing the blast upon the melted iron—which was stirred occasionally by proper iron tools—until its impurities in a great degree were expelled, and a spongy mass of forgeable iron was formed (quite similar, in fact, to that obtained when ore alone was used), which could be hammered into a "bloom."Thus far we have confined ourselves mainly to a description of methods and apparatus for the production of "sowe" or "pig" iron and "blooms," which were either in actual use in America
Fig. 15.—A Forge in 1734.
during the century following the erection of the first iron-works at Lynn, in 1645, or were coeval therewith. We now purpose to describe the early ways and means, and some of the more important improvements thereon, by which "blooms" produced by either of the before-mentioned methods were shaped into bars and rods of various forms and dimensions. The simplest means used for this purpose consisted of a hammer wielded by the muscular energy of a blacksmith.
The "hammer" was undoubtedly the first tool invented by man, and it is still not only the simplest but positively the most important tool in use; without its pioneering blows other tools could not have been fashioned, and the materials of which they are composed would have lain dormant in the earth's crust forever; for the ringing of anvils under the beating of hammers was the absolutely essential overture to the grand opera of the civilization of the human race.
If it was intended that the metal be drawn out on an anvil by "hand-hammers" and "sledges," the soft mass of iron, as it was taken from the "blomary-fire" or other furnace in which it was reduced from the ore, was cut by means of a hatchet (as shown at M N, Fig. 13) into parts not too cumbrous to be handled by ordinary smiths' tools; these pieces were then heated in a fire of larger size, blown by more powerful bellows than were commonly used by a blacksmith. One of these enlarged smiths' fires is shown in Fig. 15 (taken from Swedenborg's De Ferro), and the tools used are shown scattered about the floor. It will be noted that there are two bellows, and that these are operated by a water-wheel.
When, as was usually the case, the purpose was to make from the iron bars and rods for the general purposes of trade, the bloom resulting from shingling (as before described) the spongy mass of crude iron was reheated and drawn into the desired shape under the blows of a ponderous piece of machinery called a trip-hammer. This, although of the same name, was quite different in construction from that already described as having been used for shingling the crude iron. One of these forge triphammers is shown in Fig. 16, in which H is the head of the hammer; this was sometimes made of wrought iron, but more often was cast of the proper form and provided with an aperture through which the wooden beam forming the "helve" was passed and secured by wedges. W is the anvil, and a the "bloom," whose movements are guided and controlled by the "hammer-man" (3); while his assistant (2) determines the rapidity and force of the blows, by varying the amount of water supplied to the waterwheel which actuates the hammer. The clumsy, heavily iron-hooped, wooden shaft Y, of the water-wheel, was in this instance placed parallel with the helve of the hammer. Fastened in the circumference of this shaft were a number of round wooden pins, which, as they successively came in contact with the under side of the helve, forcibly threw it up against the spring-beam, 13, whose recoil increased the velocity of descent of the hammer and consequently the force of the blow.
Unless the bars made were of very great thickness, only a part of the bloom could be drawn out before it became too cold to be hammered; in which case the bar, with that portion of the bloom which adhered to it, was taken to a fire and reheated; sometimes several of these reheatings were necessary before the
Fig. 16.—A Forge Trip-Hammer.
whole of the bloom was forged into a bar. At 1 (Fig. 16) is seen a bar, B, whose end is being reheated as described. Whenever it was desired to make round bars, the hammer was provided with a groove of nearly semicircular section, located on one side of the middle of its striking surface or "face"; and the anvil had a corresponding groove; the "bloom" was first drawn down on the plain part of the anvil to a square section, and then this square bar was rounded in the grooves of hammer and anvil.
[To be continued.]
- In the preparation of these papers I am indebted to James M. Swank, Vice-President and General Manager of the American Iron and Steel Association, for the opportunity to consult the library of the Association; and for extracts from his very valuable contribution, Iron in all Ages, to the history of the manufacture of iron and steel. I am also under obligation to E. C. Potter, Second Vice-President of the Illinois Steel Company, for engravings and photographs of parts of the very extensive works of that company. John Thomas, Superintendent of the Thomas Iron Company, Hokendauqua, Pennsylvania, has kindly furnished me with some interesting facts relative to the first anthracite blast-furnace; and from J. Vaughan Merrick and James Moore, of Philadelphia, I have received information in regard to the early use of the Nasmyth steam hammer in the United States. I am also indebted to Oliver Williams, Esq., President of the Catasauqua Manufacturing Company, of Catasauqua, Pennsylvania, for information relative to the manufacture of anthracite iron at that place. I also acknowledge with pleasure the kind offices of W. H. Wahl, Ph. D., Secretary of the Franklin Institute, and James Gayley, Esq., Superintendent of Furnaces at the Edgar Thomson Steel Works.
- Perhaps the expression "a pair of bellows," which in the days of "open hearth" practice in our older kitchens was quite common, had its origin in an equivalent Egyptian colloquialism.
- De Re Metallica, Basilae, 1546.
- Metallurgy, Iron and Steel, Loudon, 1864.
- Le Machine, Roma, 1629
- The Manufacture of Iron, Philadelphia, 1650.
- The average record of the. cupola blown by these square wooden "blowing-tubs" was eleven pounds of metal melted by one pound of fuel. Very few cupolas now in use do as well, and by far the greater number are not more than half as economical.—W. F. D.
- Lewis's History of Lynn, 1844.
- By C. H. J. Woodbury, Esq., of Lynn.
- The Present State of New England, 1677.
- "Sowe iron" was an elongated mass of cast iron, tapering at each end, and having a triangular cross-section; it was often twenty feet in length, and weighed from twelve to fifteen hundred pounds. It was made by running the fluid iron from the furnace into a trench in sand, where it solidified.
- From De Ferro, by Emanuel Swedenborg, 1734.
- Memoires d'Artillerie, 1647.
- From Recueil de Planches, sur les Sciences, les Arts Liberaux, et les Arts Méchaniques avec leur explications. A Paris, 1765.
- L'art de convertir le fer forgé en Acier, et L'art d'adoueir le fer fondu. Par Monsieur de Réaumur, de l'Académie Royale des Sciences. Paris, 1722.
- Pig iron is usually in the form of roughly semi-cylindrical masses about two and one half feet in length, and weighing in the vicinity of one hundred pounds each. These "pigs" derive their name from being cast in the same "bed" with the "sow," in side-channels communicating with the main trench.
- The term wrought iron doubtless originated as a descriptive designation from the necessity of distinguishing iron that could be readily "wrought" or shaped as desired from "sowe" or other forms of "cast iron" which could not be "wrought" under the hammer.
- Such persons are in these days called "inventors," and are generally regarded as the originators of the various ideas and devices which they urge upon the attention of mankind; but they are, strictly speaking, simply vehicles and avenues by and through which knowledge continually comes into the world for the steady advancement of civilization. Columbus did not "invent" America, and was no more responsible for its existence than the trumpet for the note of command that issues from its resounding muzzle. This is not said in disparagement of "inventors," but only in explanation of their true function and relation to civilization. Certainly no more honorable fame, or honest wealth, can fall to any man than that which comes from being the recognized means by which beneficent knowledge is discovered; therefore all honors and rewards to such "inventors," the true prophets of science and human progress.
- Derives its name from the province of Catalonia, in the north of Spain, where it has been used for many centuries.
- From the Anglo-Saxon blôma, a mass or lump; iscnes blôma, a mass or lump of iron.
- So called from the fact that it is "tripped up" and allowed to fall, by the pins on the rim of the smaller of the two wheels shown in the illustration (Fig. 12). This form of hammer is also called a "shingling hammer."
- The "Catalan forge" or "blomary fire" has been an important factor in the growth of the iron industry of the United States, but it belongs to an industrial stage of the past. In 1856 J. P. Lesley, Secretary of the American Iron Association, reported two hundred and four blomaries in active work (in nine States), whose product for that year was 28,633 tons: many of these works must have been idle, as the product seems a very low one, averaging but one hundred and forty tons each. In 1889 James M. Swank, Vice-President and General Manager of the American Iron and Steel Association, reports but five forges (four in New York and one in Tennessee), producing iron direct from the ore; their united product being 12,407 net tons of blooms.
- Bishop's History of American Manufactures.
- From the German "Ose" ring, and "Mund" mouth,
- From the German "Stück," bloom (piece), and "Ofen," furnace.
- Metallurgy of Iron and Steel. By John Percy, M. D., F. R. S. p. 321. London, 1864,
- This process is even now worked to a limited extent, but its use is steadily declining. Mr. Swank reports that "the production of blooms and billets from pig and scrap iron in 1889 was 23,853 net tons, against 25,787 tons in 1888, and 28,218 tons in 1887."