One of the most tantalizing questions in 18th century upholstery is that of springing.
16th CENTURY QUEST FOR STEEL
Having examined ancient use of native metals and advancements in smelting and processing ores for production of an array of devices including mostly war weapons and tools, but also torsion springs in fibula jewelry and helix springs for jewelry and other unknown reasons, let’s now focus on several driving forces that advanced metallurgy mostly in iron and steel production quantity and quality and horology–the making of accurate clocks.
As I previously mentioned, the Anitkythera Mechanism was an ancient geared computer that predicted moon and planetary motions. Further research has found it to be astonishing accurate and the origins of the mechanics and the concepts are believed to be traced back to Archimedes and Cicero—and this Greek knowledge passed on to Byzantium in the Eastern Roman Empire and ultimately passed on to Islamic scholars where the principles of the gears and functions was introduced in astrolabes—essential devices for mariners and astronomers. Astrolabe gear works then show up in the15th century clock revolution and quest for accurate time pieces.
Iron production1 and steel developments at this season of history should draw our attention. Metallurgical works such as Agricola’s De Re Metallica of 1556, Pirotechnia by Biringuccio in 1540, Treatise on Ores and MInerals by Erckerin 1574, 1611 Treatise of Metallica, Metallum Martis 1665 Lord Dudley and L’ Art de Convertir le Fer Forge en Acier by Rene Reaummur of the French Academie des Sciences in 1722—did not deliver any new knowledge to help advancements in steel works. The progress was made in workshops and forges all over Europe.
“The fifteenth century saw a number of developments, notably the introduction of the spring as the driving agent for clocks (earlier clocks were all weight driven). Spring-driven clocks had the great advantage that they were portable; their subsequent miniaturization led to the improvement of the watch circa 1500.” 2
Iron must be heated to extremely high temperatures to achieve high grade steel suitable for technical performance. From the beginning of the Iron Age to the first Industrial RevolutionIn, using antiquated bloom type (ceramic or brick kiln) furnaces—metalworkers mixed raw iron ore with charcoal (for its carbon content) and by means of a manual bellows forced large amounts of oxygen into the kiln thus reaching 1200 degree C. This type iron had between 2%-5% carbon content and could be a hard and brittle—material unsuitable for flexible springs. It had to be forged and hammered into the desired shape.
HUNTSMAN’S PURSUIT AND GENIUS
Benjamin Huntsman had established himself in Doncaster, England as a clockmaker. Huntsman made locks and tools, and, experimented with the objective of finding a better material for clock springs and pendulums. Between 1740 and 1742 he moved to Handsworth, England on the outskirts of Sheffield. He began researching methods of obtaining high-grade steel production. Huntsman was able to make satisfactory cast steel in clay pot crucibles3—each of about 35 pounds of blistered steel, then added a flux and covered it for several hours4. His steel product was so hard that local Sheffield cutlery makers refused to buy from Huntsman so he exported it to French cutler makers. Eventually the British government intervened and stopped the export and forced locals to buy Huntsman’s steel. Huntsman did not apply for a patent and so his secret was out. The long search for continuous quality, high-grade precision steel was finally achieved.5
Higher purity iron which yielded higher quality steel for watches and clocks came from Sweden, Russia, and America6—all used by the famous Newcastle and Sheffield steelmakers.
Whether by the natural iron and alloy mixtures native to certain regional deposits, or by experimentation of adding ingredients such as manganese, chromium7, tungsten—more suitable steel with the valued technical characteristics such as tensile strength, hardness, etc.—Styrian steel became the best formulation prior to Huntsman—having 0.8% carbon and 0.04% manganese—perfect for springs. The Huntsman facility remained in practice and use until the mid-20th century and was only discontinued at the beginning of World War II.
IDEAS SPRUNG FROM BLACKSMITH SHOPS
As Huntsman grade high-quality crucible steel was rapidly spreading across Europe and the Atlantic Ocean to America, the developments in carriage and coach designs for comfort and efficiency drove a new use for metal springs. Local blacksmith shops began to create custom specialty products in all aspect of hardware and it is commonly believed that springs—probably single leaf springs—were first used for carriage suspension to protect the frame and cushion the ride. Complex multiple plate leaf springs probably followed—providing more durability and suspension. Coiled helical springs followed.
In all my research, one the best comprehensive accounts of the entire development and use of furniture springs was written by Clive D. Edwards Eighteenth Century Furniture, 1996 : “A patent was granted as far back as 1706 to a Henry Mills for springs to be used in coaches and chaises. However as Dorothy Holley (1981) has noted, there was no specific reference to the essential for an early upholstery spring, namely the coil, in this patent. Further patents associated with springs were taken out during the course of the18th century. In 1724 Thomas Roger took out a patent for a steel-worm or rolling spring to be used in coaches, etc. A little later in 1762, Richard Treadwell was granted a patent for an ‘iron machine for moulding and setting all kinds of springs for hanging coaches’. Treadwell also received five other patents elated to springing between 1759 and 1766. The first mention of spiral springs appears to be taken out in 1769 by Joseph Jacob for the ‘construction of wheeled carriages, by application of united spiral springs, hoop wheels and leather boxes.’
The connection between carriage springs and upholstery may seem tenuous, but it should be remembered that blacksmiths produced metal works for carriage makers as well as cabinet makers and nexus where the individual needs of the various makers were ultimately shared or borrowed cross industries.
Upholstery systems are deliberate attempts at building up a support from the base through the suspension, filling, undercover, and finally top covers.The early techniques of upholstering were simple but workmanlike. An account of the process published in 1688 demonstrated the systematic but basic technique:
‘Girth it with webbing drawn and crossed. Canvice it by nailing canvas onto the frame over the web. Rowle it by putting rowls (rolled pads) on the top edges. Stuffing follows with hay, wool, flock, or feathers. It is assumed that the cover goes on at this time. Backing is to fix the back of the chair. Garnishing is to finish it with brass nails’.
By the mid-18th century the procedure followed a similar pattern: webbing was stretched to form an interlaced support over which was fixed hessian. Curled hair was laid onto this, and stitched through to the webbing to prevent excessive movement. A roll edge was made by fixing a tube of stuffing material to the front rail to maintain the shape at this wear point. A layer of linen was fixed over the hair and then the final top cover was closely fitted. Loose seat and backs were upholstered in the same way.
In these systems the quality of the filling was important for success. Hay, wool, hair were common, but there were various attempts to develop alternative fillings. The ideas ranged from feather cushions to pigs’ bladders filled with air. The air-bags are an unknown quantity, but Edward Joy (1965) showed that the feathers were clearly a success story. The feather import figures show the valuation in 1700 as L600, in 1750 as L1086, and in 1800 as L23,810. Samuel Grant an upholsterer in Boston charged between three and four shillings per pound of feathers. The cost of some of the upholstered items would therefore be expensive. If a complete bed required 60 pounds of feathers, the charge would have exceeded L10, When this is compared to a bed frame cost of L3-1/2, the expense is put into perspective.
A technical development, which was originally meant to stabilize the filling, soon turned into a design feature. This method was tufting. The process used cords that were inserted through the thickness of the pad, but held the fillings firm and level. This technique introduced into England and America in the mid-18th century, suited the flatter, squarer design of the chairs rather than the most fashionable domed squab seats favored in France.
One of the most tantalizing questions in 18th century upholstery is that of springing. Commonly thought to be a 19th century innovation, there is evidence of earlier use. The initial demand for springs seemed to have come from two sources. The first came from coach (carriage) makers and the second from cabinet-makers (furniture makers).
Initially, furniture makers’ interest in spring technology seems to have been related to making health-related items. The first known sprung furniture appears to be the 18th century chamber horses, designed for indoor exercise. Edward Pinto mentions examples and describes these sprung horses in some detail. Pinto noted that the earliest reference to these objects appears to be 1739, when Henry Marsh of Clare Market advertised himself as the inventor of the chamber horse. Other examples, quoted by Pinto included two chamber horses supplied to the Royal household of George III which were made ‘with mahogany and spring seats’.
It is not until Thomas Sheraton’s Drawing Book that a contemporary source is able to give details of the making process. Having outlined the construction particulars of the framing, Sheraton then gives a very clear description of the spring making process: ‘strong wire is twisted round a block in regular gradation, so that when the wire is compressed by the weight of those who exercise each turn may clear itself and fall within each other.’ it is evident by the description and the illustration accompanying it that the springs were waisted-helical in shape. The springs were mounted on wainscot boards and were effective as an exerciser but there was no intension on imparting comfort. Indeed the top of the horse was simply a board upholstered with hair or similar material. The use of springs in chamber horses continued well into the 19th century with the 1823 edition of The London Chair Makers Book of Prices listing details of how the chamber horse is to be made and including the cost of ‘turning the springs’ for it.
It can be inferred from this description of making chamber horses (above) that it is likely that the production of the springs was often in the upholsterers own hands. Indeed, there are examples of the Gillow factory quoting for chamber horses and estimating the quantity of wire required for making the springs.
The English chamber horse was not the only example of upholstery springing in the 18th century. In fact, the idea of introducing springs into seat upholstery may well have come from Germany. Some accounts of a German blacksmith was responsible for the invention of coil spring and suggest it was first used in making sprung bed bases. Mattresses were indeed made with interior springs but it is difficult to show whether they proceeded chairs or vice versa.”
As Edward’s chronology is an astoundingly complex and interwoven story, my own research has convinced me that patents are by no means an accurate way in dating an innovation, a technique, or a process. We can almost be certain that the abundance of independent watch and clock makers, carriage and coach makers, blacksmith shops, foundries, academic researchers, and tinkerers came up with ideas and probably produced multiple prototypes types of springs in the 150 years between 1700-1850.
My conclusion is that most of these components were hand-produced, low economy of scale, possibly one-of-a-kind, were rather expensive, and rare curiosities to the general public. They probably existed ubiquitously but weren’t suited for an application yet and were most likely unknown to the common man.
- The first British patent covering smelting of iron was obtained by Simon Sturtevant in 1611—a patent of which shares included Prince Henry, Prince Charles, and the King himself.
- The Ferrous Metallurgy Of Early Clocks And Watches, M. Waymon, British Museum No. 136
- heated by means of a coke furnace
- “According to the French metallurgist, M. Jars, who visited the works in 1765, the crucibles measured nine to eleven inches in height, and they were much smaller than those employed today**; in these the iron was brought to the fluid state by continuous heating for five hours, and a special flux, the nature of which was jealously guarded, was added to the steel during the course of the operation. The intense heat to which the crucibles were brought had the effect of freeing the metal from the small particles of silicate or slag which existed in even the best quality of iron and steel made by older methods. When the refining process was considered complete the glowing crucibles were removed from the furnace with a long pair of tongs; the molten metal was ‘teemed’ into moulds, and thereafter it was forged into bars and slit into rods of a size convenient for the manufacture into articles of cutlery” Iron And Steel In The Industrial Revolution, Thomas Ashton, p. 55-56, Manchester Press, 1924. ** Today in 1924—the Huntsman factory was still in operation when Ashton wrote this work.
- The production of clock springs and watch springs had become two distinct trade crafts by the early 18th century.
- American steel was not insignificant with 2640 tons of pig iron being exported from Virginia and Maryland in 1750.
- Shang Dynasty swords were recovered in Xian, China among the archaeological site where the famous terra cotta warriors and these have chromium plating 10-15 microns thick to prevent corrosion. Officially the Germans invented chromium plating in 1937—but actual practice predates that by 2200 years!