Jet, a sort of semi-jewellery in its usual applications, is one of those many substances which have a kind of mysterious brotherhood with coal. The beautiful pearly white paraffin for candles comes from coal; so does the benzoline which we use in our handy little sponge lamps; so do the gorgeous magenta and analine dyes and pigments; and so, some people think, does jet. In this last-named instance, if coal is to be mentioned at all, we should rather say that jet is a kind of coal, not that it is produced from coal. Be this as it may, jet, a shining black substance, is found in seams dissociated from all other black minerals; not in the coal regions, but in other districts of England, notably near Whitby, in Yorkshire. It occurs also in Spain, in Saxony, and in the amber districts on the Prussian shores of the Baltic.
Scientific men, in the language of mineralogy, say that jet is a variety of coal; that it occurs sometimes in elongated masses, sometimes in the form of branches, with a woody structure; that its fracture is conchoidal or shelly, its lustre brilliant and resinous, and its color velvet black; that it is about twenty per cent. heavier than water; that it burns with a greenish flame, emits a bituminous odor while burning, and leaves a yellowish ash. But the Whitby folks can adduce many reasons for thinking that jet, in some of its forms at any rate, must have been at one time in a semi-liquid state, quite unlike coal derived from a ligneous origin. Mr. Simpson, curator of the Whitby Museum, states that that collection comprises among its specimens a large mass of bone which has had the exterior converted into or replaced by jet. This jet coating is about a quarter of an inch thick. The jetty matter appears to have entered into the pores of the bone, and there to have hardened; during this hardening or mineralizing process, the bony matter has been gradually displaced and supplanted by jet, the original form of the bone being maintained. Another reason for thinking that the jet or some of it, must once have been in a gummy or semi-liquid state, is that bits of vegetable and miucral substances are sometimes found imbedded in it, as flies, wings, and small fragments are in amber. Cavities and fissures in the adjacent rocky strata are also sometimes found filled with it, as if it had flowed into them originally. The stratum called "jet-rock," in which the Whitby jet is mostly found, is a kind of shale, when distilled, yields ten gallons of oil per ton. That in a remote geological era there was an intimate relation between this oil and the jet is very probable; though its exact nature cannot now be determined. The Yorkshire coast for many miles north and south of Whitby is a storehouse of jet. The deposit occurs in the lias formation, the jet-rock being interlaid with other lias strata. Two kinds are found in different beds or layers, the hard and the soft jet. The hard, which is in all respects the best, occurs in detached compact layers or pieces, from small bits no bigger than dominoes to pieces of many pounds' weight. The largest piece recorded measured six feet long, five to six inches wide, and an inch and a half thick; it weighed nearly twelve pounds. The British Museum refused to give ten guineas for this fine specimen; whereupon it was sold for fifteen guineas to a dealer, who had it carved into crosses of exceptionally large size.
For how long a period jet, or black amber as it was at one time called, has been found and worked near Whitby, no one can now say; but the time certainly ranges over many centuries. In a tumulus or barrow opened in the vicinity of the town, was found tie skeleton of a lady–supposed to have been ancient British before the date of the arrival of the Danes–and with it was a jet earring, two inches long by a quarter of an inch in thickness, shaped like a heart, and pierced with a hole at the upper end for the reception of a ring or wire. The substance was, in the middle ages, made at Whitby into beads and rosaries, probably by the monks or friars.
As a branch of regular trade, Whitby jet work was of not much account till about the beginning of the present century. The Spaniards made the principal beads and rosaries for Roman Catholic countries of a soft kind of jet; but when English ladies began to wear jet as mourning jewellery, the superior hardness of the Whitby material induced some of the townsmen to attend to this kind of work. The first workers employed nothing but knives and files in fashioning the ornaments; but one Matthew Hill gave an extension to the trade by finding the means of turning the jet in a lathe–a more difficult matter than turning wood, owing to the brittleness of the material. In a short time there were ten or twelve shops in Whitby, where jet beads, necklaces, crosses, pendants, and snuff boxes were made and sold. About thirty years ago, Mr. Bryan, the chief representative of the trade, obtained the largest " find" of jet ever known, from a spot in the neighborhood called the North Bats; it comprised three hundred and seventy pieces or " stones," valued at two hundred and fifty pounds. There were fifty workshops engaged in the trade at the time of the first Great Exhibition in 1851; the number now exceeds two hundred.
According to an interesting account of this industry by Mr. Bower, the jet is obtained by two modes of operation, cliff-work and hill-work. Pieces of j et washed out by the sea from fissures in the face of the cliff are, indeed, sometimes picked up on the beach; but these are few in number, unreliable for purposes of regular trade. In cliff-work, portions of the face of the cliff are hewn down, until seams of jet are made visible; and the jet is picked out from these scams so long as it can be got at. This is somewhat dangerous employment, owing to the precipitous nature of the cliffs. In hill-work, diggings are made in the Cleveland hills, near Bilsdale, about twenty miles inland from Whitby. Tunnels are driven' into the hillsides, driftways and lateral passages are driven, and jet-rock is thus laid bare in various spots; picks and other instruments extract the pieces of jet, which small wagons running upon a tramway bring to the tunnel's mouth. The find is always precarious, especially in cliff-work; sometimes no jet is obtained in a month's work ; while, in other instances, a lucky hit will bring to light a valuable harvest. At present the hill-work is most adopted, and there are about twenty small mines at the Cleveland hills. The men rent the workings, as at the Cornish copper and tin mines; their profits represent their wages, and depend on the ratio between the richness of the seam and the rent paid; insomuch that the miners have every motive for exercising judgement and discrimination in the bargains they may make. The best hard jet will realize, when in large pieces, thirty shillings per pound; whereas the poorest soft pieces are barely worth a shilling a pound; these extremes are separated by many intermediate gradations of value. The Whitby hard is the finest jet known, having more toughness and elasticity than any other, admitting of more delicate working, and taking a higher polish. On the other hand the Spanish soft is better than the Whitby soft: and experts say that many ornaments sold in the shops as genuine Whitby, came from beyond the Pyrenees, and were never made of Whitby jet at all. They look well at first, but are apt to break up under the influence of sudden heat and cold, and are in other respects far from durable. This fragility is believed to be due to a small percentage of sulphur which most Spanish jet contains.
Let us suppose that pieces of jet, varying much in size and shape, are brought to the workshop. The rough jet has a kind of exterior skin or crust, often marked by impressions of ammonites and other fossils, and presenting various tints of bluish brown. This skin is removed by means of a large chisel. At the sawing-bench the piece is then cut up with saws. This process requires much discrimination, seeing that the size and shape of the piece must determine the kind, size, and number of ornaments obtained from it; the great object is to waste as little of the substance as possible. From the saw-bench, the jet passes into the hands of the carvers and turners. The turning is effected by a careful use of small lathes. The carving is effected by grinding rather than cutting, grindstones of various kinds being used, and the jet applied to them in succession–first to grind away, and then to polish. In this way most of the beads, necklaces.bracelets, crosses, brooches, lockets, chainlinks, etc., are made, as well as bas-reliefs, floral designs, and monograms. A clever workman will get twenty per cent, more value out of the same piece of jet than a man of less skill and judgement, by adapting his design to the size and shape of the piece. Soft jet is much wasted during working, by the presence of fibres, grit. etc.; it is therefore better fitted for beads than for intricate ornaments. Much use is made of the cutting mill, a disc or wheel of soft metal, about eight inches in diameter; the edge, or rim, made sharp and set in rapid revolution, cuts the jet. quickly and smoothly. The surfaces of the carved or turned ornaments are polished by being held against the edge of a revolving wheel, covered with walrus or bull-neck leather, and wetted with copperas and oil The edges, scrolls, curls and twists, require that the wheel edge shall be covered with list; and then comes a final application to a brush-wheel. The beads for necklaces, bracelets, etc., are put together with strong twisted threads and small wires. Chains are made by turning- and carving the links separately, splitting some of them, and inserting the unsplit into the split links; small wires are inserted where necessary, and the split closed up with a cement of shellac and resin. Pendants, ear-drops, etc., are linked in a similar way. Some of the jet, when rough-cut at Whitby, is bought by Birmingham jewellers, who finish it according to their own taste.
Whether jet forms a suitable material for small ornaments is surely a matter of taste, as it is in regard to coral, black pearls, and bog oak. The jet trade is increasing, and now gives employment to fifteen hundred hands in Whitby and its neighbourhood. The influence of fashion is shown in a remarkable way when the death of any great personage at court is announced, such as that of the Duke of Wellington, or of the Prince Consort; at such a time Whitby can hardly meet the sudden demand for jet jewellery suitable for mourning. Once now and then, however, the joy of the nation is the sorrow of jet dealers. When the Prince of Wales lay prostrate with illness, dealers purchased somewhat largely, in order to be prepared for eventualities. When the Prince recovered there was a larger stock of jet jewellery ready than the public wanted, and so the commodity did not "look up " in the market.
Whitby and Birmingham are trying to improve the designs for jet carvings and turnings; and there is no doubt room for improvement. When a new start was given to the trade at the first great Exhibition, the Art Journal engraved some new designs suitable to this peculiar material. The beneficial result was seen at the next Exhibition, eleven years afterwards; and still more decidedly at the second of the two annual International Exhibitions, when jet ornaments took their place in the jewellery display of that year. Two or three years ago, the Turners' Company of London having offered prizes for meritorious specimens of turning in wood, ivory and other material, the judges were agreeably surprised at having placed before them a vase turned in jet. The Whitby maker had skilfully cemented two or more pieces together, to obtain a sufficient bulk of the substance for the purpose ; and his honorary reward was, the Freedom of the City of London. Jet is usually found in such thin seams, that nearly all the ornaments made of it are flat and of small thickness; cementing is occasionally adopted where two pieces are suitable for being joined face to face; but all attempts to work up fragments, cuttings, turnings, and powder into a paste of homogeneous mass, have hitherto failed. This can be done with amber, and with the meerschaum clay for pipe-bowls; but no mode has yet been devised for adopting the same course with jet.
As in most other trades, a love of cheapness acts frequently as a bar to the attainment of any high degree of technical skill. A shopkeeper will show his lady customer two jet brooches or necklaces almost exactly alike in appearance; she is prone to select the cheaper of the two, regardless of the fact that the other presents higher claims as a specimen of art workmanship. If called by its right name, an excellent material of recent introduction would deserve much commendation; but when announced as imitation jet, and still more when allowed to pass for jet itself, it deserves the censure that is due to all shams. We speak of ebonite or vulcanite, a very tough material, prepared with India rubber and other substances, smooth and black, but not taking so high a polish as jet. Black glass does duty for a large quantity of cheap mourning jewellery, innocently supposed by many of the wearers to be jet. Another substitute is wood-powder, blacked, moulded and hardened. A still more remarkable material is paper pulp, cast or pressed into blocks, rolled into sheets, cut up, ground on wheels, blacked and polished. But, naturally enough, these substitutes for the genuine article find no favor in Whitby.
Source: Locke's National Monthly - 1873