Early Machines of Sir Samuel Bentham—Evolution of the Saw—Circular Saw—Hammering to Tension—Steam Feed for Saw Mill Carriage—Quarter Sawing—The Band Saw—Planing Machines—The Woodworth Planer—The Woodbury Yielding Pressure Bar—The Universal Woodworker—The Blanchard Lathe—Mortising Machines—Special Woodworking Machines.
Surrounded as we are in the modern home with beautiful and artistic furniture, and installed in comfortable and inexpensive houses, one does not appreciate the contrast which the life of the average citizen of to-day presents to that of his great-grandfather in the matter of his dwelling house appointments. A hundred years ago most of the dwellings of the middle and poorer classes were crudely made, with clap-boards and joists laboriously hewn with the broad ax, and the roof was covered with split shingles. Uncouth and clumsy doors, windows and blinds, were framed on the simplest utilitarian basis, and a scanty supply of rude hand-made furniture imperfectly filled the simple wants of the home. To-day nearly every cottage has beautifully moulded trimmings, paneled doors, handsomely carved mantels and turned balusters, all furnished at an insignificant price, and art has so added its æsthetic values to the furniture and other useful things in wood, that beautiful, artistic and tasteful homes are no longer confined to the rich, but may be enjoyed by all. This great change has been brought about by the sawmill, the planing machine, mortising and boring machines, and the turning lathe.
Pre-eminent in the field of woodworking machinery, and worthy to be called the father of the art, is to be mentioned the name of Gen. Sir Samuel Bentham, of England, whose inventions in the last decade of the Eighteenth Century formed the nucleus of the modern art of woodworking.
The Saw was the great pioneer in woodworking machinery, and the circular saw has, in the Nineteenth Century, been the representative type. Pushing its way along the outskirts of civilization, its glistening and apparently motionless disk, filled with a hidden, but terrific energy, and singing a merry tune in the clearings, has transformed trees into tenements, forests into firesides, and altered the face of the earth, the record of its work being only measured by the immensity of the forests which it has depleted. It is not possible to fix the date of the first circular saw, for rotary cutting action dates from the ancient turning lathes. The earliest description of a circular saw is to be found in the British patent to Miller, No. 1,152, of 1777. It was not until the Nineteenth Century, however, that it was generally applied, and its great work belongs to this period. The preceding saws were of the straight, reciprocating kind. The old pit-saw is the earliest form, and in course of time the men were replaced by machinery to form the “muley” saw, the man in the pit being replaced by a mechanical “pitman,” which accounts for the etymology of the word. With the “muley” saw the log was held at each end, and each end shifted alternately to set for a new cut. The first development was along the lines of this form of saw, and to increase its efficiency the saws were arranged in gangs, so as to make a number of cuts at one pass of the log. This type was especially used in Europe, but on the up stroke there was no work being done, and hence half of the time was lost. This and other difficulties led finally to the adoption of the circular type, whose continuous cut and high speed saved much time and presented many other advantages. A representative example of the circular saw is given in Fig. 241.
With the increased diameter and peripheral speed of the circular saw, however, a grave difficulty presented itself. The saw would heat at its periphery, and its rim portion expanding without commensurate expansion of the central portion, would cause the saw to crack and fly to pieces under the tremendous centrifugal force. This difficulty is provided for by what is known as “hammering to tension,” i. e., the saw is hammered to a gradually increasing state of compression from the rim to the center, thus causing an initial expansion or spread of the molecules of metal of the central parts of the saw, which is stored up as an elastic expansive force that accommodates itself to the tension caused by the expansion of the rim, and prevents the unequal and destructive strain, due to the expansion of the rim from the great heat of friction in passing through the log.
Mounted upon a portable frame, this machine was put to its great work upon the logs in the forests of America, and for many years this type of sawmill held its sway, and an enormous amount of work was done through its agency. Among its useful accessories were the set-works for adjusting the log holding knees to the position for a new cut, log turners for rotating the log to change the plane of the cut, and the rack and pinion feed, by which the saw carriage was run back and forth. Following the rack and pinion feed came the rope feed, in which a rope wrapped around a drum was carried at its opposite ends over pulleys and back to the opposite ends of the carriage, which was thereby carried back and forth by the forward or backward movement of the drum.
The greatest advance in sawmills in recent years, however, has been the steam feed, in which a very long steam cylinder was provided with a piston, whose long rod was directly attached to the saw carriage, and the latter moved back and forth by the admission of steam alternately to opposite sides of the piston. This type of feed, also known as the shot gun feed, from the resemblance of the long cylinder to a gun barrel, was invented about twenty-five years ago, by De Witt C. Prescott, and is covered by his patent, No. 174,004, February 22, 1876, later improvements being shown in his patent, No. 360,972, April 12, 1887. The value of the steam feed was to increase the speed and efficiency of the saw, by expediting the movement of its carriage, as many as six boards per minute being cut by its aid from a log of average length. An example of a modern steam feed for sawmill carriages is seen in Fig. 242. With the modern development of the art the ease and rapidity of steam action have recommended it for use in most all of the work of the sawmill, and the direct application of steam pistons working in cylinders has been utilized for canting, kicking, flipping and rolling the logs, lifting the stock, taking away the boards, etc.
Beautifully finished furniture in quartered oak has always excited the pleasure, and piqued the curiosity of the uninformed as to how this result is obtained. Fig. 243 illustrates the method of sawing to produce this effect. The log is simply divided longitudinally into four quarters, and the quarter sections are then cut by the vertical plane of the saw at an oblique angle to the sawed sides, which brings to the surface of the boards the peculiar flecks or patches of the wood’s grain so much admired when finished and polished.
The Band Saw is an endless belt of steel having teeth formed along one edge and traveling continuously around an upper and lower pulley, with its toothed edge presented to the timber to be cut, as seen in Fig. 244, which represents a form of band saw made by the J. A. Fay & Egan Company, of Cincinnati. A form of band saw is found as early as 1808, in British patent No. 3,105, to Newberry. On March 25, 1834, a French patent was granted for a band saw to Etiennot, No. 3,397. The first United States patent for a band saw was granted to B. Barker, January 6, 1836, but it remained for the last quarter of the Nineteenth Century to give the band saw its prominence in woodworking machines. That it did not find general application at an earlier period was due to the difficulty experienced in securely and evenly joining the ends of the band. For many years the only moderately successful band saws were made in France, but expert mechanical skill has so mastered the problem that in recent years the band saw has gone to the very front in wood-sawing machinery. To-day it is in service in sizes from a delicate filament, used for scroll sawing and not larger than a baby’s ribbon, to an enormous steel belt 50 feet in peripheral measurement, and 12 inches wide, traveling over pulleys 8 feet in diameter, making 500 revolutions per minute, and tearing its way through logs much too large for any circular saw, at the rate of nearly two miles a minute. A modern form of such a saw is seen in Fig. 245. Prescott’s patents, Nos. 368,731 and 369,881, of 1887; 416,012, of 1889, and 472,586 and 478,817, of 1892, represent some of the important developments in the band saw.
When the band saw is applied to cutting logs the backward movement of the carriage would, if there were any slivers on the cut face of the log, be liable to force those slivers against the smooth edge of the band saw, and distort and possibly break it. To obviate this the saw carriage is provided with a lateral adjustment on the back movement called an “off-set,” so that the log returns for a new cut out of contact with the saw. Examples of such off-setting are found in patents to Gowen, No. 383,460, May 29, 1888, and No. 401,945, April 23, 1889, and Hinkley, No. 368,669, August 23, 1887. A modern form of the band saw, however, has teeth on both its edges, which requires no off-setting mechanism, but cuts in both directions. An example of this, known as the telescopic band mill, is made by the Edward P. Allis Company, of Milwaukee.
A saw which planes, as well as severs, is shown in patents to Douglass, Nos. 431,510, July 1, 1890, and 542,630, July 16, 1895. Steam power mechanism for operating the knees is shown in patent to Wilkin, No. 317,256, May 5, 1885. Means for quarter sawing in both directions of log travel are shown in patent to Gray, No. 550,825, December 3, 1895. Means for operating log turners and log loaders appear in patents to Hill, No. 496,938, May 9, 1893; No. 466,682, January 5, 1892; No. 526,624, September 25, 1894, and Kelly, No. 497,098, May 9, 1893. A self cooling circular saw is found in patent to Jenks, No. 193,004, July 10, 1877; shingle sawing machines in patents to O’Connor, No. 358,474, March 1, 1887, and No. 292,347, January 22, 1884, and Perkins, No. 380,346, April 3, 1888; and means for severing veneer spirally and dividing it into completed staves, are shown in patent to Hayne, No. 509,534, November 28, 1893.
Planing Machines.—While the saw plays the initial part of shaping the rough logs into lumber, it is to the planing machine that the refinements of woodworking are due. Its rapidly revolving cutter head reduces the uneven thickness of the lumber to an exact gauge, and simultaneously imparts the fine smooth surface. The planing machine is organized in various shapes for different uses. When the cutters are straight and arranged horizontally, it is a simple planer. When the cutters are short and arranged to work on the edge of the board they are known as edgers; when the edges are cut into tongues and grooves it is called a matching machine; and when the cutters have a curved ornamental contour it is known as a molding machine, and is used for cutting the ornamental contour for house trimmings and various ornamental uses.
The planing machine was one of the many woodworking devices invented by General Bentham. His first machine, British patent No. 1,838, of 1791, was a reciprocating machine, but in his British patent No. 1,951, of 1793, he described the rotary form along with a great variety of other woodworking machinery.
Bramah’s planer, British patent No. 2,652, of 1802, was about the first planing machine of the Nineteenth Century. It is known as a transverse planer, the cutters being on the lower surface of a horizontal disc, which is fixed to a vertical revolving shaft, and overhangs the board passing beneath it, the cutters revolving in a plane parallel with the upper surface of the board. The planing machine of Muir, of Glasgow, British patent No. 5,502, of 1827, was designed for making boards for flooring, and represented a considerable advance in the art.
With the greater wooded areas of America, the rapid growth of the young republic, and the resourceful spirit of its new civilization, the leading activities in woodworking machinery were in the second quarter of the Nineteenth Century transferred to the United States, and a phenomenal growth in this art ensued. Conspicuous among the early planing machine patents in the United States was that granted to William Woodworth, December 27, 1828. This covered broadly the combination of the cutting cylinders, and rolls for holding the boards against the cutting cylinders, and also means for tongueing and grooving at one operation. The revolving cutting cylinder had been used by Bentham thirty-five years before, and rollers for feeding lumber to circular saws were described in Hammond’s British patent No. 3,459, of 1811, but Woodworth did not employ his rolls for feeding, as a rack and pinion were provided for that, but his rolls had a co-active relation with a planer cylinder, or cutter head, in holding the board against the tendency of the cutter head to pull the board toward it. A patent was granted to Woodworth for these two features in combination, which patent was reissued July 8, 1845, twice extended, and for a period of twenty-eight years from its first grant, exerted an oppressive monopoly in this art, since it covered the combination of the two necessary elements of every practical planer.
Following the Woodworth patent came a host of minor improvements, among which were the Woodbury patents, extending through the period of the third quarter of the Nineteenth Century, and prominent among which is the patent to J. P. Woodbury, No. 138,462, April 20, 1873, covering broadly a rotary cutter head combined with a yielding pressure bar to hold the board against the lifting action of the cutter head.
In modern planing machinery the climax of utility is reached in the so-called universal woodworker. This is the versatile Jack-of-all-work in the planing mill. It planes flat, moulded, rabbeted, or beaded surfaces; it saws with both the rip and crosscut action; it cuts tongues and grooves; makes miters, chamfers, wedges, mortises and tenons, and is the general utility machine of the shop.
In Fig. 246 is shown a well known form of planing machine. Its work is to plane the surfaces of boards, and to cut the edges into tongues and groves, such as are required for flooring. This machine planes boards up to 24 inches wide and 6 inches thick, and will tongue and grove 14 inches wide.
Wood Turning.—To this ancient art Blanchard added, in 1819, his very ingenious and important improvement for turning irregular forms. A few efforts at irregular turning had been made before, but in the arts generally only circular forms had been turned. With Blanchard’s improvement, patented January 20, 1820, any irregular form, such as a shoe-last, gun-stock, ax-handle, wheel-spokes, etc., could be smoothly and expeditiously turned and finished in any required shape. In the ordinary lathe the work is revolved rapidly, and the cutting tool is held stationary, or only slowly shifted in the hand. In the Blanchard lathe the work is hung in a swinging frame, and turned very slowly to bring its different sides to the cutting action, and the cutting tool is constructed as a rapidly revolving disk, against which the work is projected bodily by the oscillation of the swinging frame, to accommodate the irregularities of the form. In order to do this automatically, a pattern or model of the article to be turned was also hung in the swinging frame, and made to slowly revolve and bear against a pattern wheel, which, acting upon the swinging frame carrying the work, caused it to advance to or recede from the cutting disc exactly in proportion to the contour of the model, and thus cause the revolving cutters to cut the block as it turns synchronously with the model, to a shape exactly corresponding to said model.
In Fig. 247 is shown a perspective view of Blanchard’s lathe, as patented January 20, 1820. H is a swinging frame, carrying the model T of a shoe last, and a roughed-out block U, partly converted into a shoe last. A sliding frame, fed horizontally by a screw, carries a pattern wheel K, that bears against the pattern T, and a rotary cutter E, acting against the roughed-out block U. The revolving disk-shaped cutter E is rotated by a pulley and belt from a drum, which latter is made long enough to accommodate the travel of the frame. The pattern T and block U are advanced to contact respectively, with pattern wheel K and cutter E by the swinging action of frame H, and as the pattern T and block U are slowly revolved, the travel of T against K is made to react on frame H and regulate the advance of U against E, with the result that the rough block U is cut to the identical shape of the pattern T.
Among modern developments in this art may be mentioned the patents to Kimball, No. 471,006, March 15, 1892, and No. 498,170, May 23, 1893, the latter showing ingenious means whereby shoe lasts of the same length, but varying widths, may be turned. A polygonal-form lathe is shown in patent to Merritt, No. 504,812, September 12, 1893; a multiple lathe in patents to Albee, No. 429,297, June 3, 1890, and Aram, No. 550,401, November 26, 1895; a tubular lathe in patent to Lenhart, No. 355,540, January 4, 1887; and a spiral cutting lathe in patent to Mackintosh, No. 396,283, January 15, 1889.
Mortising Machines have exercised an important influence in mill work in the joining of the stiles in doors, sashes and blinds, and in the making of furniture. The Fay & Egan machine is seen in Fig. 248. The self acting mortising machine was among the numerous early contributions of Gen. Bentham in woodworking machinery, and was described in his British patent No. 1,951, of 1793, a number of them having been made by him for the British Admiralty. Brunel’s mortising machine for making ships’ blocks is another early form described in British patent No. 2,478, of 1801. As representing novel departures in this art, the endless chain mortising machine shown in Douglas patent, No. 379,566, March 20, 1888, may be mentioned, and reissue patent, No. 10,655, October 27, 1885, to Oppenheimer, and No. 461,666, October 20, 1891, to Charlton, are examples of mortising augers.
Special Woodworking Machines.—Of these there have been great numbers and variety. No sooner does an article become extensively used than a machine is made for turning it out automatically. Indeed, machines for cheaply turning out articles have, in many cases, led the way to popular use of the article by the extreme cheapness of its production.
Among various automatic machines for making special articles may be mentioned those for making clothes pins, scooping out wood trays, pointing skewers, dovetailing box blanks, cutting sash stile pockets, cutting and packing toothpicks, making matches, boxing matches, duplicating carvings, cutting bungs, cutting corks, making umbrella sticks, making brush blocks, boring chair legs, screw-driving machines, box nailing machines, making cigar boxes, nailing baskets, wiring box blanks, applying slats, gluing boxes, gluing slate frames, making veneers, bushing mortises, covering piano hammers, making staves and barrels, making fruit baskets, etc.
It is impossible to give in any brief review a proper conception of the immensity of the woodworking industry in the United States. It is estimated in the Patent Office that about 8,000 patents have been granted for woodworking machines. Besides this there are about 5,000 patents in the separate class of wood sawing, about an equal number for woodworking tools, and these, with other patented inventions in wood turning, coopering, or the making of barrels, wheelwrighting, and other minor classes, give some idea of the activity in this great field of industry.
The exports of wood and wooden manufactures from the United States in 1899 amounted to $41,489,526, of which $15,031,176 were for finished boards, $4,107,350 for barrels, staves and heads, and $3,571,375 for household furniture, but this is only an insignificant portion, for with a prosperous country, an abundance of wood, and a thrifty and ambitious nation of home builders, the home consumption has been incalculable.
Early Iron Furnace—Operations of Lord Dudley, Abraham Darby and Henry Cort—Neilson’s Hot Blast—Great Blast Furnaces of Modern Times—The Puddling Furnace—Bessemer Steel and the Converter—Open Hearth Steel—Siemens’ Regenerative Furnace—Siemens-Martin Process—Armor Plate—Making Horse Shoes—Screws and Special Machines—Electric Welding, Annealing and Tempering—Coating with Metal—Metal Founding—Barbed Wire Machines—Making Nails, Pins, etc.—Making Shot—Alloys—Making Aluminum, and Metallurgy of Rarer Metals—The Cyanide Process—Electric Concentrator.
Take away iron and steel from the resources of modern life, and the whole fabric of civilization disintegrates. The railroad, steam engine and steamship, the dynamo and electric motor, the telegraph and telephone, agricultural implements of all sorts, grinding mills, spinning machines and looms, battleships and firearms, stoves and furnaces, the printing press, and tools of all sorts—each and every one would be robbed of its essential basic material, without which it cannot exist. Steam and electricity may be the heart and soul of the world’s life, but iron is its great body. King among metals, it gives its name to the present cycle, as the “Iron Age,” and the Nineteenth Century has crowned it with such refinements of shape, and endowed it with such attributes of utility, and such grandeur of estate, that its powers in organized machinery have, for effective service, risen to all the functions and dignity of human capacity—except that of thought.
A crude gift of nature, in the mountain side, it remained, however, a sodden mass until extracted, refined, and wrought into shape by the genius of man. Yielding to the magical touch of invention, it has been cast in moulds into cannon, mills, plowshares, and ten thousand articles; it has been drawn into wire of any fineness and length to form cables for great suspension bridges; it has been rolled into rails that grill the continents; into sheets that cover our roofs; and into nails that hold our houses together. It has been wrought into a softness that lends its susceptible nature to the influence of magnetism, and has been hardened into steel to form the sword and cutting tool. From the delicate hair spring of a watch to the massive armor plate of a battleship, it finds endless applications, and is nature’s most enduring gift to man—abundant, cheap, and lasting.
Metallurgy is an ancient art, and the working of gold, silver and copper dates back to the beginning of history. Being found in a condition of comparative purity, and needing but little refinement, they were, for that reason, the first metals fashioned to meet the wants of man. Iron, somewhat more refractory, appeared later, but it also has an early history, and is mentioned in the Old Testament of the Bible (Genesis iv., 22), in which reference is made to Tubal Cain as an artificer in brass and iron. The iron bedstead of Og, King of Bashan, is another reference. That it was known to the Egyptians and the Greeks at least 1000 B. C., seems reasonably certain. The Assyrians were also acquainted with iron, as is clearly established by the explorations of Mr. Layard, whose contributions to the British Museum of iron articles from the ruins of Ninevah include saws, picks, hammers, and knives of iron, which are believed to be of a date not later than 880 B. C.
Iron ore is usually found in the form of an oxide (hematite), and its reduction to the metallic form consists in displacing the oxygen, which is effected by mixing carbon in some form with the ore, and subjecting the mixture to a high heat by means of a blast. The carbon unites with the oxygen and forms carbonic acid gas, which escapes, while the metallic iron fuses and runs out at the bottom of the furnace, and when collected in trough-shaped moulds, is known as pig iron.
The first iron furnaces were known as air bloomeries, and had no forced draft. The first step of importance in iron making was the forced blast. An early form of blast furnace is shown in Fig. 249, which represents an iron furnace of the Kols, a tribe of iron smelters in Lower Bengal and Orissa. An inclined tray terminates at its lower end in a furnace inclosure. Charcoal in the furnace being well ignited, ore and charcoal resting on the tray are alternately raked into the furnace. The blowers are two boxes, connected to the furnace by bamboo pipes, and provided with skin covers, which are alternately depressed by the feet and raised by cords from the spring poles. Each skin cover has a hole in the middle, which is stopped by the heel of the workman as the weight of the person is thrown upon it, and is left open by the withdrawal of the foot as the cover is raised. The heels of the workman, alternately raised, form alternately acting valves, and the skin cover, when depressed, acts as a bellows. The fused metal sinks to a basin in the bottom of the furnace, and the slag or impurities run off above the level of the basin at the side of the furnace.
The great modern art of iron working dates from Lord Dudley’s British patent, No. 18, of 1621, which related to “The mistery, arte, way and meanes of melting iron owre, and of makeing the same into cast workes or barrs with seacoales or pittcoales in furnaces with bellowes of as good condicon as hath bene heretofore made of charcoale.”
The next step of importance after the blast furnace was the substitution of coke for coal for the reduction of the ore, which was introduced by Abraham Darby, about 1750.
Next came the conversion of cast iron into wrought iron. This was mainly the work of Mr. Henry Cort, of Gosport, England, who, in 1783-84, introduced the processes of puddling and rolling, which were two of the most important inventions connected with the production of iron since the employment of the blast furnace. Mr. Cort obtained British patents No. 1,351, of 1783, and No. 1,420, of 1784, for his invention. His first patent related to the hammering, welding, and rolling of the iron, while in his second patent he introduced what is known as the reverberatory furnace, having a concave bottom, into which the fluid metal is run from the smelting furnace, and which is converted from brittle cast iron, containing a certain per cent. of carbon, into wrought iron, which has the carbon eliminated, and is malleable and tough. This process is called puddling, and consists in exposing the molten metal to an oxidizing current of flame and air. The metal boils as the carbon is burned out, and as it becomes more plastic and stiff it is collected into what are called blooms, and these are hammered to get rid of the slag, and are reduced to marketable shape as wrought iron by the process described in his previous patent. Mr. Cort expended a fortune in developing the iron trade, and was one of the greatest pioneers in this art.
The first notable development of the Nineteenth Century was the introduction of the hot air blast in forges and furnaces where bellows or blowing apparatus was required. This was the invention of J. Beaumont Neilson, of Glasgow, and was covered by him in British patent No. 5,701 of 1828. This consisted in heating the air blast before admitting it to the furnace, and it so increased the reduction of refractory ores in the blast furnace as to permit three or four times the quantity of iron to be produced with an expenditure of little more than one-third of the fuel.
An illustration of a modern blast furnace plant is given in Fig. 250. A is the furnace, in which the iron ore and fuel are arranged in alternate layers. The hot air blast comes in through pipes t at the bottom, called tuyeres. As gas escapes through the opening b at the top, it is first cleared of dust in the settler and washer B, and then passes through the pipe C to the regenerators D D D, where it is made to heat the incoming air. The gas mixed with some air burns in the regenerators, and, after heating a mass of brick within the regenerators red hot, escapes by the underground passageway to the chimney on the right. When the bricks are sufficiently hot in one of the regenerators, gas is turned off therefrom, and into another regenerator, and fresh air from pipe H is passed through the bricks of the heated regenerator, and being heated passes out pipe F at the top and thence to the pipe G and tuyeres t, to promote the chemical reactions in the blast furnace.
In the earlier blast furnaces a vast amount of heat was allowed to escape and was wasted. The utilization of this heat engaged the attention of Aubertot in France, 1810-14; Teague in England (British patent No. 6,211, of 1832); Budd (British patent No. 10,475, of 1845), and others. To enable the escaping hot gases to be employed for heating the hot blast regenerators a charging device is now used, as seen at a in Fig. 250, in which the admission of ore and fuel is regulated by a large conical valve, and the gases are compelled to pass out at b and be utilized.
Among the world’s largest blast furnaces may be mentioned the Austrian Alpine Montan Gesellschaft, which concern owns thirty-two furnaces. This is said to be the largest number owned by any one concern in the world, but most of them are of small size and run on charcoal iron. The furnaces of the United States are, however, of the largest yield, and the leading ones of these are:
| No. Furnaces. |
Annual capacity in tons. |
|
|---|---|---|
| Carnegie Steel Co. | 17 | 2,200,000 |
| Federal Steel Co. | 19 | 1,900,000 |
| Tennessee Coal and Iron Co. | 20 | 1,307,000 |
| National Steel Co. | 12 | 1,205,000 |
The present annual output of pig iron in the United States is about ten million tons, of which these four companies make about one-half.
When the iron runs from the bottom of the blast furnace it is allowed to flow into trough-like moulds in the sand of the floor, and forms pig iron. Pig iron can be remelted and cast into various articles in moulds, but it cannot be wrought with the hammer, nor rolled into rails or plates, nor welded on the anvil, because it is still a compound of iron and carbon with other impurities, and is crystalline in character. To bring it into wrought iron, which is malleable and ductile, it is puddled and refined, which involves chiefly the burning out of the carbon and silicon. The pig iron is remelted (see Fig. 251) in the tray-shaped hearth b from the heat of the fire in the reverberatory furnace a, the reverberatory furnace being one in which the materials treated are exposed to the heat of the flame, but not to contact with the fuel. The hot flame mixed with air beating down upon the melted iron on hearth b for two hours or so, burns out the silicon and carbon, the process being facilitated by stirring and working the mass with tools. During the operation the oxygen of the air combines with the carbon and forms carbonic acid gas, which, in escaping from the metal, appears to make it boil. When the iron parts with its carbon it loses its fluidity and becomes plastic and coherent, and is formed into balls called blooms. These blooms consist of particles of nearly pure iron cohering, but retaining still a quantity of slag or vitreous material, and other impurities, which slag, etc., is worked out while still, hot by a squeezing, kneading, and hammering process to form wrought iron that may be worked into any shape between rolls or under the hammer.
Bessemer Steel.—Steel is a compound of iron and carbon, standing between wrought iron and cast iron. Wrought iron has, when pure, practically no carbon in it, while cast iron has a considerable proportion in excess of steel. Steel making consists mainly in so treating cast iron as to get rid of a part of the carbon and other impurities. Of all methods of steel making, and in fact of all the steps of progress in the art of metal working, none has been so important and so far reaching in effect as the Bessemer process: It was invented by Henry Bessemer, of England, in 1855. About fifty British patents were taken by Mr. Bessemer relating to various improvements in the iron industry, but those representing the pioneer steps of the so-called Bessemer process are No. 2,321, of 1855; No. 2,768, of 1855, and No. 356, of 1856. The process is illustrated in Figs. 252, 253 and 254. The converter in which the process is carried out is a great bottle-shaped vessel 15 feet high and 9 feet wide, consisting of an iron shell with a heavy lining of refractory material, capable of holding eight or more tons of melted iron, and with an open neck at the top turned to one side. It is mounted on trunnions, and is provided with gear wheels by which it may be turned on its trunnions, so that it may be maintained erect, as in Fig. 252, or be turned down to pour out the contents into the casting ladle, as in Figs. 253 and 254. At the bottom of the converter there is an air chamber supplied by a pipe leading from one of the trunnions, which is hollow, and a number of upwardly discharging air openings or nozzles send streams of air into the molten mass of red hot cast iron. The red hot cast iron contains more or less carbon and silicon, and the air uniting with the carbon and silicon burns it out, and in doing so furnishes the heat for the continuance of the operation. When the pressure of air is turned into the mass of molten iron a tongue of flame increasing in brilliancy to an intense white, comes roaring out of the mouth of the converter, and a violent ebullition takes place within, and throws sparks and spatters of metal high in the air around, producing the impression and scenic effect of a volcano in eruption. In fifteen minutes the volume and brilliancy of the flame diminish, and this indicates the critical moment of conversion into tough steel, which must be adjusted to the greatest nicety. When the carbon is sufficiently burned out the blast is stopped and the converter turned down to receive a quantity of ferro-manganese or spiegeleisen (a compound of iron containing manganese), which unites with and removes the sulphur and oxide of iron, and then the lurid monster, with its breath of fire abated, and its energy exhausted, bows its head and vomits forth its charge of boiling steel, to be wrought or cast into ten thousand useful articles.
FIG. 253.—POURING THE MOLTEN METAL.
Side view of Bessemer converterFIG. 254.—SIDE VIEW, SHOWING TURNING GEARS.
Like most all valuable inventions, Mr. Bessemer’s claim to priority for the invention was contested. An American inventor, William Kelly, in an interference with Mr. Bessemer’s United States patent, successfully established a claim to the broad idea of forcing air into the red hot cast iron, and United States patent No. 17,628, June 23, 1857, was granted to Mr. Kelly. The honor of inventing and introducing a successful process and apparatus for making steel by this method, however, fairly belongs to Mr. Bessemer, to whose work was to be added the valuable contribution of Robert F. Mushet (British patent No. 2,219, of 1856) of adding spiegeleisen, a triple compound of iron, carbon and manganese, to the charge in the converter. This step served to regulate the supply of carbon and eliminate the oxygen, and completed the process of making steel. The Holly converter, covered by United States patents No. 86,303, and No. 86,304, January 26, 1869, represented one of the most important American developments of the Bessemer converter.
The importance of Bessemer steel in its influence upon modern civilization is everywhere admitted. It has so cheapened steel that it now competes with iron in price. Practically all railroad rails, iron girders and beams for buildings, nails, etc., are made from it at a cost of between one and two cents per pound.
In recognition of the great benefits conferred upon humanity by this process, Queen Victoria conferred the degree of knighthood upon the inventor, and his fortune resulting from his invention is estimated to have grown for some time at the rate of $500,000 a year. In a historical sketch of the development of his process, delivered by Sir Henry Bessemer in December, 1896, before the American Society of Mechanical Engineers at New York, Mr. Bessemer was reported as saying that the annual production of Bessemer steel in Europe and America amounted to 10,000,000 tons. The production of Bessemer steel in the United States for 1897 was for ingots and castings 5,475,315 tons, and for railroad rails 1,644,520 tons. The extent to which steel has displaced iron is shown by the fact that in the same year iron rails to the extent of 2,872 tons only were made, as compared with more than a million and a half tons of Bessemer steel.
In the popular vote taken by the Scientific American, July 25, 1896, as to what invention introduced in the past fifty years had conferred the greatest benefit upon mankind, Bessemer steel was given the place of honor.
A recent improvement in the handling of iron from the blast furnace is shown in Fig. 255. Heretofore, the iron was run in open sand moulds on the floor and allowed to cool in bars called “pigs,” which were united in a series to a main body of the flow, called a “sow.” To break the “pigs” from the “sow,” and handle the iron in transportation, was a very laborious and expensive work. The illustration shows two series of parallel trough moulds, each forming an endless belt, running on wheels. The molten cast iron is poured direct into these moulds, and as they travel along they pass beneath a body of water, which cools and solidifies the iron into pigs, and then carries them up an incline and dumps them directly into the cars.
Open Hearth Steel is not so cheap as Bessemer steel, but it is of a finer and more uniform quality. Bessemer steel is made in a few minutes by the most energetic, rapid and critical of processes, while the open hearth steel requires several hours, and its development being thus prolonged it may be watched and regulated to a greater nicety of result. For railroad rails and architectural construction Bessemer steel still finds a great field of usefulness, but for the finest quality of steel, such as is employed in making steam boilers, tools, armor plate for war vessels, etc., steel made by the open hearth process is preferred. It consists in the decarburization of cast iron by fusion with wrought iron, iron sponge, steel scrap, or iron oxide, in the hearth of a reverberatory furnace heated with gases, the flame of which assists the reaction, and the subsequent recarburization or deoxidation of the bath by the addition, at the close of the process, of spiegeleisen or ferro-manganese. The period of fusion lasts from four to eight hours. The advantages over the Bessemer process are, a less expensive plant and the greater duration of the operation, permitting, by means of sampling, more complete control of the quality of the product and greater uniformity of result.
The British patents of Siemens, No. 2,861, of 1856; No. 167, of 1861, and No. 972, of 1863, for regenerative furnaces, and the British patents of Emile and Pierre Martin, No. 2,031, of 1864; No. 2,137, of 1865, and No. 859, of 1866, represent the so-called Siemens-Martin process, which is the best known and generally used open hearth process.
The Siemens Regenerative Furnace, in which this process is carried out, is seen in Fig. 256. Four chambers, C, E, E′, C′, are filled with fire brick loosely stacked with spaces between, in checker-work style. Gas is forced in the bottom of chamber C, and air in bottom of chamber E, and they pass up separate flues, G, on the left, and being ignited in chamber D above, impinge in a flame on the metal in hearth H, the hot gases passing out flues F on the right, and percolating through and highly heating the checker-work bricks in chambers E′ and C′. As soon as these are hot, gas and air are shut off by valves from chambers C and E, and gas and air admitted to the bottoms of the now hot chambers C′ and E′. The gas and air now passing up through these chambers C′, E′, become highly heated, and when burned above the melted iron on hearth H produce an intense heat. The waste gases now pass down flues G, and impart their heat to the checker-work bricks in chambers C and E. When the bricks in E′ C′ become cooled by the passage of gas and air, the valves are again adjusted to reverse the currents of gas and air, sending them now through chambers C and E again. In this way the heat escaping to the smoke stack is stored up in the bricks and utilized to heat the incoming fuel gases before burning them, thus greatly increasing the effective energy of the furnace, saving fuel, and keeping the smoke stack relatively cool.
Armor Plate.—In these late days of struggle for supremacy between the power of the projectile and the resistance of the battleship, the production of armor plate has become an interesting and important industry.
Three methods are employed. One is to roll the massive ingots directly into plates between tremendous rolls, a single pair of which, such as used in the Krupp works, are said to weigh in the rough as much as 100,000 pounds. Usually there are three great rollers arranged one above the other, and automatic tables are provided for raising and lowering the plates in their passage from one set of rolls to the other. The man in charge uses a whistle in giving the signals which direct these movements, and without the help of tongs and levers the glowing blocks move easily back and forth between the rollers. The men standing on both sides of the rollers have only to wipe off the plates with brooms and occasionally turn the plates.
The second method utilizes great steam hammers weighing 125 tons, and striking Titanic blows upon the yielding metal. The most modern method, however, is by the hydraulic press forge, now used in the shops of the Bethlehem steel works in the production of Harveyized armor plate. In Fig. 257 is seen the great 14,000-ton hydraulic press-forge squeezing into shape a port armor plate for the battleship “Alabama.” After leaving the forge, the plate is trimmed to shape by the savage bite of a rotary saw and planer, seen in Figs. 258 and 259, whose insatiable appetites tear off the steel like famished fiends. The plate is then taken to be Harveyized by cementation, hardening, and tempering, as seen in Figs. 260, 261, and 262. The 125-ton mass of metal representing the plate in the rough, and weighing more than a locomotive, is thus handled and brought to shape with an ease and dispatch that inspires the observer with mixed emotions of admiration and awe.
Making Horse Shoes.—Anthony’s patent, April 8, 1831; Tolles’, of October 24, 1834, and H. Burden’s, of November 23, 1835, were pioneers in horse-shoe machines. Mr. Burden took many subsequent patents, and to him more than any other inventor belongs the credit of introducing machine-made horse shoes, which greatly cheapened the cost of this homely, but useful article. Nearly 400 United States patents have been granted for horse-shoe machines.
Making Screws, Bolts, Nuts, Etc.—Screw-making according to modern methods began between 1800-1810 with the operations of Maudsley. Sloan, in 1851, and Harvey, in 1864, made many improvements in machines, operating upon screw blanks. The gimlet-pointed screw, which allows the screw to be turned into wood without having a hole bored for it, was an important advance in the art. It was the invention of Thomas J. Sloan, patented August 20, 1846, No. 4,704, and was twice re-issued and extended. In later years the rolling of screws, instead of cutting the threads by a chasing tool, has attained considerable importance, and provides a simpler and cheaper method of manufacture. Knowles’ United States patent of April 1, 1831, re-issued March 1, 1833, described such a process, while Rogers, in patents No. 370,354, September 20, 1887; No. 408,529, August 6, 1889; No. 430,237, June 17, 1890, and No. 434,809, August 19, 1890, added such improvement in the process as to make it practical.
In the great art of metal working the names of Bramah, Whitworth, Clements and Sellers appear conspicuously in the early part of the century as inventors of planing, boring and turning machinery for metals. Our present splendid machine shops, gun shops, locomotive works, typewriter and bicycle factories, are examples of the wonderful extensions of this art. In later years the field has been filled so full of improvements and special machines for special work, that only a brief citation of a few representative types is possible, and even then selection becomes a very difficult task. Many special tools, particularly those designed for bicycle work, have been devised, as exhibited by patent to Hillman, August 11, 1891, No. 457,718. In turning car wheels, an improvement consists in bringing the wheel to be dressed into close proximity to the edge of a rapidly revolving smooth metal disk, whereby the surface of the wheel is melted away without there being any actual contact between the wheel surface and the disk. This is shown in patent to Miltimore, August 24, 1886, No. 347,951. In metal tube manufacture three processes are worthy of mention: (1) Passing a heated solid rod endwise between the working faces of two rapidly rotating tapered rolls, set with their axes at an angle to each other, as shown in Mannesmann’s patent, April 26, 1887, No. 361,954 and 361,955. (2) Forcing a tube into a rapidly rotating die, whereby the friction softens the tube, and the pressure and rotation of the die spin it into a tube of reduced diameter, shown in patent to Bevington, January 13, 1891, No. 444,721. (3) Placing a hot ingot in a die and forcing a mandrel through the ingot, thereby causing it to assume the shape of the interior of the die, and greatly condensing the metal, shown in patents to Robertson, November 26, 1889, No. 416,014, and Ehrhardt, April 11, 1893, No. 495,245.
In welding, the employment of electricity constitutes the most important departure. This was introduced by Elihu Thomson, and is covered in his patents Nos. 347,140 to 347,142, August 10, 1886, and No. 501,546, July 18, 1893. In annealing and tempering, electricity has also been employed as a means of heating (see patent to Shaw, No. 211,938, February 4, 1879). It supplies an even heat and uniform temperature, and is much used in producing clock and watch springs. The making of iron castings malleable by a prolonged baking in a furnace in a bed of metallic oxide was an important, but early, step. It was the invention of Samuel Lucas, and is disclosed in his British patent No. 2,767, of 1804.
The Harvey process of making armor plate is an important recent development in cementation and case hardening, and is covered by his United States patents No. 376,194, January 10, 1888, and No. 460,262, September 29, 1891. It consists, see Fig. 260, in embedding the face of the plate in carbon, protecting the back and sides with sand, heating to about the melting point of cast iron, and subsequently hardening the face. The Krupp armor plate, now rated as the best, is made under the patent to Schmitz and Ehrenzberger, No. 534,178, February 12, 1895.
In coating with metals, the so-called “galvanizing” of iron is an important art. This was introduced by Craufurd (British patent No. 7,355, of April 29, 1837), and consisted in plunging the iron into a bath of melted zinc covered with sal ammoniac. In more recent years the tinning of iron has become an important industry, and machines have been made for automatically coating the plates and dispensing with hand labor, examples of which are found in patents No. 220,768, October 21, 1879, Morewood; No. 329,240, October 27, 1885, Taylor, et al., and No. 426,962, April 29, 1890, Rogers and Player.
In metal founding the employment of chill moulds is an important step. Where any portion of a casting is subjected to unusual wear, the mould is formed, opposite that part of the casting, out of metal, instead of sand, and this metal surface, by rapidly extracting the heat at that point by virtue of its own conductivity, hardens the metal of the casting at such point. The casting of car wheels by chill moulds, by which the tread portion of the wheel was hardened and increased in wearing qualities, is a good illustration. Important types are found in patents to Wilmington, No. 85,046, December 15, 1868; Barr, No. 207,794, September 10, 1878, and Whitney, re-issue patent, No. 10,804, February 1, 1887.
In wire-working great advances have been made in machines for making barbed wire fences. The French patent to Grassin & Baledans, in 1861, is the first disclosure of a barbed wire fence. This art began practically, however, with the United States patent to Glidden and Vaughan for a barbed wire machine, No. 157,508, December 8, 1874, re-issued March 20, 1877, No. 7,566, and has assumed great proportions. A machine for making wire net is shown in patent to Scarles, No. 380,664, April 3, 1888, and wire picket fence machines are shown in patents to Fultz, No. 298,368, May 13, 1884, and Kitselman, No. 356,322, January 18, 1887. Machines for making wire nails were invented at an early period, but the product found but little favor until about 1880, when they began to be extensively used, and have almost entirely supplanted cut nails for certain classes of work, since their round cross section and lack of taper give great holding power and avoid cutting the grain of the wood. In 1897 the wire nails produced in the United States amounted to 8,997,245 kegs of 100 pounds each, which nearly doubled the output of 1896. The output of cut nails for the same year was 2,106,799 kegs.
The bending of wire to form chains without welding the links has long been done for watch chains, etc., but in late years the method has extended to many varieties of heavy chains. The patents to Breul, No. 359,054, March 8, 1887, and No. 467,331, January 19, 1892, are good examples.
An interesting class of machines, but one impossible of illustration on account of their complication, are machines for making pins. In earlier times pins had their heads applied in a separate operation. Making pins from wire and forming the heads out of the cut sections began in the Nineteenth Century with Hunt’s British patent No. 4,129, of 1817. This art received its greatest impetus, however, under Wright’s British patent No. 4,955, of 1824. A paper of pins containing a pin for every day in the year, and costing but a few cents, gives no idea to the purchaser of the time, thought and capital expended in machines for making them, and yet were it not for such machines, rapidly cutting coils of wire into lengths, pointing and heading the pins, and sticking them into papers, the world would be deprived of one of its most ubiquitous and useful articles. Many tons of pins are made in the United States weekly, and it is said that 20,000,000 pins a day are required to meet the demand.
In the metal working art the making of firearms and projectiles has grown to wonderful proportions. Cutlery and builders’ hardware is an enormous branch; wire-drawing, sheet metal-making, forging, and the making of tools, springs, tin cans, needles, hooks and eyes, nails and tacks, and a thousand minor articles, have grown to such proportions that only a bird’s-eye view of the art is possible.
In the making of shot, the old method was to pour the melted metal through a sieve, and allow it to drop from a tower 180 feet or more in height. David Smith’s patent, No. 6,460, May 22, 1849, provided an ascending current of air through which the metal dropped, and which, by cooling the shot by retarding its fall and bringing a greater number of air particles in contact with them, avoided the necessity of such high towers. In 1868, Glasgow and Wood patented a process of dropping the shot through a column of glycerine or oil. Still another method is to allow the melted metal to fall on a revolving disk, which divides it into drops by centrifugal action.
Alloys.—Over 300 United States patents have been granted for various alloys of metals. The so-called babbit metal was patented in the United States by Isaac Babbit, July 17, 1839, and in England, May 15, 1843, No. 9,724. This consists of an antifriction compound of tin, 10 parts, copper, 1 part, and antimony, 1 part, and is specially adapted for the lubricated bearings of machinery. Phosphor bronze, introduced in 1871, combines 80 to 92 parts copper, 7 of tin, and 1 of phosphorus (see United States patents to Lavroff, No. 118,372, August 22, 1871, and Levi and Kunzel, No. 115,220, May 23, 1871). The addition of phosphorus promotes the fluidity of the metal and makes very clean, fine and strong castings. In alloys of iron, chromium steel is covered by patents to Baur, No. 49,495, August 22, 1865; No. 99,624, February 8, 1870, and No. 123,443, February 6, 1872; manganese steel, by Hadfield’s patent, No. 303,150, August 5, 1884; aluminum steel, by Wittenström’s patent, No. 333,373, December 29, 1885, and phosphorus steel, by Kunkel’s patent, No. 182,371, September 19, 1876. The most recent and perhaps most important, however, is nickel steel, used in making armor for battleships. This is covered by Schneider’s patents, Nos. 415,655, and 415,657, November 19, 1889.
In 1878 England led the world in the iron industry with a production of 6,381,051 tons of pig iron, as compared with 2,301,215 tons by the United States. In 1897 the United States leads the world in the following ratios:
| Tons Pig Iron. |
Tons Steel. |
|
|---|---|---|
| United States | 9,652,680 | 7,156,957 |
| Great Britain | 8,789,455 | 4,585,961 |
| Germany | 6,879,541 | 4,796,226 |
| France | 2,472,143 | 1,312,000 |
The United States made in that year 29.30 per cent. of the world’s production of pig iron, and 34.58 per cent. of its steel. The total output of the whole world in that year was 32,937,490 tons pig iron, and 20,696,787 tons of steel.
Metallurgy of Rarer Metals.—Although less in evidence than iron, this has engaged the attention of the scientist from the earliest years of the century. The full list of metals discovered since 1800 may be found under “Chemistry.” The more important only are here given. Palladium and rhodium were reduced by Wollaston in 1804. Potassium and sodium were first separated in metallic form by Sir Humphrey Davy in 1807, through the agency of the voltaic arc; barium, strontium, calcium and boron by the same scientist in 1808; iodine by Courtois in 1811; selenium by Berzelius in 1817; cadmium by Stromeyer in 1817; silicon by Berzelius in 1823, and bromium by Balard in 1826. Magnesium was first prepared by Bussey in 1829. Aluminum was first separated in 1828 by Wohler, by decomposing the chloride by means of potassium. Oersted, in 1827, preceded him with important preliminary steps, and Deville, in 1854, followed in the first commercial applications. In late years the metallurgy of aluminum has made great advances. The Cowles process heats to incandescence by the electric current a mixture of alumina, carbon and copper, the reduced aluminum alloying with the copper. This process is covered by United States patents to Cowles and Cowles, No. 319,795, June 9. 1885, and Nos. 324,658 and 324,659, August 18, 1885. It has, however, for the most parts been superseded by the process patented by Hall, April 2, 1889, No. 400,766, in which alumina dissolved in fused cryolite is electrically decomposed.
In the metallurgy of the precious metals probably the most important step has been the cyanide process of obtaining gold and silver. In 1806 it was known that gold was soluble in a solution of cyanide of potassium. In 1844 L. Elsner published investigations along this line, and demonstrated that the solution took place only in the presence of oxygen. McArthur and Forrest perfected the process for commercial application, and it is now extensively used in the Transvaal and elsewhere. It is covered by their British patent, No. 14,174, of 1887, and United States patents No. 403,202, May 14, 1889, and No. 418,137, December 24, 1889, which describe the application of dilute solutions of cyanide of potassium, not exceeding 8 parts cyanogen to 1,000 parts of water: the use of zinc in a fine state of division to precipitate the gold out of solution, and the preparatory treatment of the partially oxidized ores with an alkali or salts of an alkali. By this solution-process gold, in the finest state of subdivision, which could not be extracted by other processes from the earthy matters, may be recovered and saved in a simple, practical and cheap way.
FIG. 263.—EDISON MAGNETIC CONCENTRATING WORKS. THE GIANT CRUSHING ROLLS.
In the working of ores of gold and silver the old method of comminution of the rock and the separation of the gold and silver by amalgamation with mercury has given birth to thousands of inventions in stamp mills, amalgamators, ore washers, concentrators and separators. In the treatment of iron ores, and especially those of low grade, the magnetic concentrator is an interesting and striking departure. This method goes back to the first half of the Nineteenth Century, an example being found in the patent to Cook, No. 6,121, February 20, 1849. Edison’s patent, No. 228,329, June 1, 1880, is however, the basis of the first practical operations in which magnets, operating by attraction upon falling particles of iron ore, are made to separate the particles rich in iron from the sand. In Fig. 263 is shown the Edison magnetic concentrating apparatus. The ore, in masses of all sizes up to boulders of five or six tons weight, is dumped between the giant rolls, and these enormous masses are crunched and comminuted more easily than a dog crunches a bone. These gigantic rolls are six feet in diameter, six feet long, and their surfaces are covered with crushing knobs. They weigh with the moving machinery seventy tons, and when revolved at a circumferential speed of 3,500 feet in a minute, their insatiable and irresistible bite soon chews the rock into fragments that pass into similar crushing rolls set closer together until reduced to the desired fineness. The sand is then raised to the top of the concentrating devices, shown in Fig. 264, and is allowed to fall in sheets from inclined boards in front of a series of magnets, of which four sets are shown in the figure. These magnets deflect the fall of the particles rich in iron (which are attracted), while the non-magnetic particles of sand drop straight down. A thin knife-edge partition board, arranged below the falling sheets of sand, separates the deflected magnetic particles from the straight-falling sand. These magnetic particles are then collected and pressed into little bricks, which are now so rich in iron, by virtue of concentration, as to make the final reduction of the iron in the blast furnace easy and profitable. More recent developments in this art are shown in patents to Wetherill, No. 555,792, March 3, 1896, and Payne, No. 641,148, January 9, 1900.
In the production of copper the well-known Bessemer process for refining iron is now largely used, as shown in patent to Manhes, No. 456,516, July 21, 1891, in which blasts of air are forced through the melted copper to remove sulphur and other impurities. Electrolytic processes of refining copper are also largely used, as described in Farmer’s patent, No. 322,170, July 14, 1885.
The production of metals, other than iron, in the United States for the year 1897, was as follows: