Popular Technology Volume II Part 18

28. The gem-engraver and the jeweller were both employed by Moses, in preparing the ornaments in the ephod and breast-plate of the high-priest. In the former were set onyx stones, and in the latter, twelve different stones. On the gems of both ornaments, were engraved the names of the twelve tribes of Israel.

39. We, however, have evidence of the practice of the arts, connected with the production of jewelry, long before the days of the Jewish lawgiver. We learn from the twenty-fourth chapter of Genesis, that the servant of Abraham presented a golden ear-ring, and bracelets for the hands, to Rebecca, who afterwards became the wife of Isaac. Perhaps these were brought from Egypt by the patriarch, about seventy years before.

30. Men have ever been fond of personal ornaments, and there have been but few nations since the flood, which have not encouraged the jeweller in some way or other. In modern times, the art has been greatly improved. The French, for lightness and elegance of design, have surpa.s.sed other nations; but the English, for excellence of workmanship, have been considered, for ages, unrivalled.

31. In the United States, the manufacture of jewelry is very extensive, there being large establishments for this purpose in Philadelphia, and in Newark, N. J., as well as in several other places. So extensive have been the operations in this branch of business, and to such advantage have they been carried on, that importations from other countries have ceased, and this, too, without the influence of custom-house duties.

32. The capital necessary in carrying on the business of the jeweller, is considerable, inasmuch as the materials are very expensive. The operations likewise require the exercise of much ingenuity. These, however, we shall not attempt to describe, since our article on this subject has already been extended beyond its proper limits, and since, also, they could be hardly understood without actual inspection.

[Ill.u.s.tration: WATCH MAKER.]

THE SILVERSMITH, AND THE WATCH-MAKER.

SILVER.

1. Silver is a metal of a fine white color, and, in brilliancy, inferior to none of the metals except steel. In malleability, it is next to gold, it being capable of reduction into leaves not more than the 1/160000 of an inch in thickness, and of being drawn into wire much finer than a human hair.

2. The relative value of silver and gold has varied considerably in different ages. In the prosperous period of ancient civilization, one pound of gold was worth twelve of silver. In Great Britain, the relative value of the two metals is one to fifteen and one-fifth, and, on the continent of Europe, it is about one to fifteen. In the United States, the relative value of these two metals has been recently established by Congress at one to sixteen. In China and j.a.pan, it is said to be one to nine or ten.

3. There are two methods of separating silver from its various ores, and these are called _smelting_ and _amalgamation_. In the former method, the ore and a due proportion of lead are heated together; and the latter, from its great affinity for silver, unites with it, and separates it from other substances. The two metals are afterwards separated from each other, by melting them on a cupel, and then exposing them to a current of atmospheric air, by which the lead is converted into an oxyde, while the silver remains untouched. This process is called _cupellation_.

4. In the other method, the first thing done is to roast the ore, to expel the sulphur and other volatile parts. It is then reduced to an impalpable powder by machinery; and having been sifted, it is agitated sixteen or eighteen hours in barrels, with a quant.i.ty of quicksilver, water, and iron, combined in certain proportions. This agitation causes the several substances composing the _charge_, to unite according to their respective affinities.

5. The silver and mercury combine, forming an amalgam, which, having been put into a leather sack, a part of the latter is separated from the rest by filtration, still leaving six parts of this metal to one of the silver. The amalgam is next submitted to the action of heat in a distilling furnace, by which the mercury is sublimated.

6. The value of the silver annually taken from the mines in all parts of the world, is supposed to be about $20,000,000, of which Mexico and South America yield the greater part. The several silver mines of Europe and Asia produce about two millions and a half.

THE SILVERSMITH.

1. The artisan who forms certain articles of gold and silver, is called indifferently a goldsmith or a silversmith. The former denomination is most commonly employed in England, and the latter, in the United States.

2. The most common subjects of manufacture by the silversmith are cups, goblets, chalices, tankards, spoons, knives, forks, waiters, bread-trays, tea-pots, coffee-pots, cream-pots, sugar-bowls, sugar-tongs, and pencil-cases. Many of these articles he sometimes makes of gold; this is especially the case in Europe, and some parts of Asia. In the United States, the people are commonly satisfied with the less expensive metal.

3. A great proportion of the silver used by this mechanic, has been previously coined into dollars. In working these into different utensils or vessels, he first melts them in a crucible, and casts the silver into solid ma.s.ses by pouring it into iron moulds; and having forged it on an anvil, he reduces it still further, and to a uniform thickness, by pa.s.sing it several times between steel rollers. In giving additional explanations of the operations of the silversmith, we will describe the manner in which a plain tea-pot is manufactured.

4. In forming the body, or containing part, the plate, forged and rolled as just described, is cut into a circular form, and placed on a block of soft wood with a concave face, where it is beaten with a convex hammer, until it has been brought to a form much like that of a saucer. It is then placed upon an anvil, and beaten a while with a long-necked hammer with a round flattish face.

5. It is next _raised_ to the proposed form by forging it on a long slender anvil, called a _stake_, with a narrow-faced hammer, which spreads the metal perpendicularly from the bottom, or laterally, according to the position in which it may be held when brought in contact with the metal.

6. After the piece has been thus brought to the proposed form, it is _planished_ all over by beating it with a small hammer on the outside, while it rests on a small steel head on the inside. During the performance of these operations, the silver is occasionally _annealed_ by heating it in the fire; but it is worked while in a cold state, except in the first forging, when it is wrought while a little below red heat.

7. The several pieces which compose a tea-pot of ordinary construction, amount to about fifteen, nearly all of which are rolled and forged in the manner just described. The k.n.o.b on the lid, the handle, and the spout, are sometimes cast, and at other times, the two pieces of which they are formed are cut from a plate, and brought to a proper figure by impressing them with steel dies.

8. The figures seen on the cheaper kinds of silver tea-pots, as well as on other vessels and utensils, are commonly made by pa.s.sing the plates or strips between engraved steel rollers, or by stamping them with steel dies. The dies are commonly brought in sudden and violent contact with the metal by means of an iron _drop_, which is let fall from a height upon it.

9. After the several parts have been brought to the proper shape, and to the requisite finish, they are firmly united together by means of a solder composed of about three parts of silver and one of bra.s.s and copper. Before the spout and handle are soldered on, the other parts, which have been thus united into one piece, are brought to a certain degree of polish.

10. This is effected chiefly in a lathe, by holding against the piece, while in rapid motion, first a file, then a sc.r.a.per, and afterwards pumice stone and Scotch stone. It is then held against a rapidly revolving brush, charged with fine brickdust and sweet oil. The handle and spout are next soldered on. After this, the vessel is annealed, and put in _pickle_, or, in other words, into a weak solution of oil of vitriol. It is then scoured with sand and water, and the whole operation is completed by burnishing the smooth parts with a steel instrument.

11. In the more expensive kinds of wares, the raised figures and the frosty appearance are produced by a process called _chasing_. In executing this kind of work, a drawing is first made on the silver with a lead pencil. The several parts are then raised from the other side, corresponding as nearly as possible to it. The vessel or piece is then filled with, or placed upon, melted cement, composed of pitch and brick-dust; and, after the cement has become hard by cooling, the chaser reduces the raised parts to the form indicated by the drawing, by means of small steel punches. The roughness of surface, and frosty appearance, are produced by punches indented on the end.

12. The operations of the silversmith are exceedingly various, many of which could be hardly understood from mere description. We would, therefore, recommend to the curious, actual inspection, a.s.suring them that the ingenuity displayed in executing the work in the different branches of the business, is well worthy of their attention. We will merely add, that spoons, knives, and forks, are not cast, as is frequently supposed, but forged from strips of silver cut from rolled sheets.

13. The earliest historical notice of gold and silver is found in the thirteenth chapter of Genesis, where it is stated that Abraham returned to Canaan from Egypt, "rich in cattle, in silver, and in gold." This event took place about 1920 years before Christ, it being but little more than 400 years after the deluge. From the authority of the same book, we also learn, that during the life of this patriarch, those metals were employed as a medium of commercial intercourse, and as the materials for personal ornaments, vessels, and utensils.

14. From the preceding facts, we have reason to believe that gold and silver were known to the antediluvians; for, had not this been the case, they could hardly have been held in such estimation so early as the time of Abraham. In short, they were probably wrought even in the days of the original progenitor of the human race, as was evidently the case with iron and copper.

THE CLOCK AND WATCH MAKER.

1. The great divisions of time, noted by uncivilized men, are those which are indicated by the changes of the moon, and the annual and diurnal revolutions of the earth; but the ingenuity of man was very early exercised in devising methods of measuring more minute periods of duration.

2. The earliest contrivance for effecting this object was the sun-dial. This instrument was known to the ancient Egyptians, Chaldeans, Chinese, and Bramins. It was likewise known to the Hebrews, at least as early as 740 years before Christ, in the days of Ahaz the king. The Greeks and the Romans borrowed it from their Eastern neighbors. The first sun-dial at Rome was set up by Papirius Cursor, about 300 years before Christ. Before this period, the Romans determined the time of day by the rude method of observing the length of shadows.

3. The sun-dial, as it is now constructed, consists of a plate, divided into twelve equal parts, like the face of a clock, on which the falling of a shadow indicates the time of day. The shadow is projected by the sun, through the intervention of a rod or the edge of a _plate stile_ erected on the plane of the dial. But, since the dial was useful only in the clear day, another instrument was invented, which could be used at all times, in every variety of situation; and to this was given the name of _clepsydra_.

4. This instrument is supposed to have been invented in Egypt; but, at what period, or by whom, it is not stated. Its construction was varied, in different ages and countries, according with the particular modes of reckoning time; but the constant dropping or running of water from one vessel into another, through a small aperture, is the basis in all the forms which it has a.s.sumed. The time was indicated by the regularly increasing height of the water in the receiving vessel.

5. The clepsydra was introduced into Greece by Plato, near 400 years before Christ, and, about 200 years after this, into Rome, by Scipio Africa.n.u.s. It is said that Pompey brought a valuable one from the East, and that Julius Caesar met with one in England, by which he discovered that the summer nights were shorter there than in Italy.

6. The use which Pompey made of his instrument, was to limit the length of speeches in the senate. Hence he is said, by a historian of those times, to have been the first Roman who put bridles upon eloquence. A similar use was made of the clepsydra in the courts of justice, first in Greece, and afterwards in Rome.

7. A kind of water-clock, or clepsydra, adapted to the modern divisions of time, was invented near the middle of the seventeenth century; and these were extensively used, in various parts of Europe, for a considerable time; but they are now entirely superseded by our common clocks and watches, which are far more perfect in their operation, and, in all respects, better adapted to the purposes to which they are applied.

8. The invention of the clock is concealed in the greatest obscurity.

Some writers attribute it to the monks, as this instrument was used in the twelfth century in the monasteries, to regulate the inmates in their attendance on prayers both by night and by day. Others suppose that a knowledge of this valuable instrument was derived from the Saracens, through the intercourse arising from the crusades. Be this as it may, clocks were but little known in Europe, until the beginning of the fourteenth century.

9. Richard, abbot of St. Alban's, England, made a clock in 1326, such as had never been heard of until then. It not only indicated the course of the sun and moon, but also the ebbing and flowing of the tide. Large clocks on steeples began to be used in this century. The first of this kind is supposed to have been made and put up in Padua by Jacobus Dondi.

10. A steeple clock was set up in Boulogne, in 1356; and, in 1364, Henry de Wyck, a German artist, placed one in the palace of Charles V., king of France. In 1368, three Dutchmen introduced clock-work into England, under the patronage of Edward III. Clocks began to be common both in England and on the Continent, about the end of the fifteenth century.

11. The clock of Henry de Wyck is the most ancient instrument of this kind of which we have a description. The wheels were made of wrought iron, and the teeth were cut by hand. In other respects, also, it was a rude piece of mechanism, and not at all capable of keeping time with accuracy. But, rude as it was, it is not likely that it was the invention of a single individual; but that, after the first rude machine was put in motion, it received several improvements from various persons. This has, at least, been the case with all the improvements made on the clock of Henry de Wyck, to the present day.

12. The application of the pendulum to clock-work appears to have been first made by Vincenzo Galileo, in 1649; but the improvement was rendered completely successful, in 1656, by Christian Huygens, a Dutch philosopher. The laws of the oscillation of the pendulum were first investigated by Galileo, the great Italian philosopher, and father of the Galileo just mentioned. His attention was attracted to this subject by the swinging of a lamp suspended from the ceiling of the Cathedral, at Pisa, his native city.

13. The clocks first made were of a large size, and were placed only in public edifices. The works were, at length, reduced in their dimensions, and these useful machines were gradually introduced into private dwellings. They were finally made of a portable size, and were carried about the person. These portable clocks had, for their maintaining power, a main-spring of steel, instead of a weight, which was used in the larger time-keepers.

14. The original pocket-watches differed but little, if at all, in the general plan of their construction, from the portable clocks just mentioned. The transition from one kind of instrument to the other was, therefore, obvious and easy; but the time of the change cannot be certainly determined. It is commonly admitted, however, that Peter Hele constructed the first watch, in 1510.

15. Watches appear to have been extensively manufactured at Nuremburg, in Germany, soon after their invention, as one of the names by which they were designated, was _Nuremburg eggs_. These instruments, as well as clocks, were in common use in France, in 1544, when the company of clock and watch makers of Paris was first incorporated.

16. In 1658, the spring balance was invented by Doctor Nathaniel Hooke, an English philosopher. At least the invention is attributed to him by his countrymen. On the Continent it is claimed for Christian Huygens. Before this improvement was made, the performance of watches was so defective, that the best of them could not be relied upon for accurate time an hour together. Their owners were obliged to set them often to the proper time, and wind them up twice a day.

17. After the great improvements had been effected in the clock and watch by Huygens and Hooke, several others of minor importance were successively made by different persons; but our limits do not allow us to give them a particular notice; we will only state that the repeating apparatus of both clocks and watches was invented, about the year 1676, by one Barlow, an Englishman; that the compensation or gridiron pendulum was invented by George Graham, of London, in 1715; and that jewels were applied to watches, to prevent friction, by one Facio, a German.