Chapter IX: Part 9

But, perhaps, the antiquity of the use of black-lead pencils cannot be so well determined from diplomatiques, as their frequency might be proved from mineralogical writers. The first mention of this discovery occurs in the works of Gesner, who, in his “Book of Fossils,” published in 1565, says that the British people had pencils for writing, with wooden-handles inclosing a piece of lead, which he believed to be an artificial composition; and it was called _stimmi Anglicanum_; which seems to import that it was a British production; and we should consider, from the name of British antimony being given to it, that it might have been Cumberland black-lead.

About thirty years afterwards, Cæsalpinus gave a more perfect account of it:--he says it was a lead-coloured, shining stone, as smooth as glass, and appeared as if rubbed over with oil; it gave to the fingers an ash-grey tint, with a plumbeous brightness; and, he adds, pointed pencils were made of it, for the use of painters and draughtsmen. A closer description of the substance than this cannot be discovered.

Somewhere about three years afterwards, a still more perfect description was furnished by Imperatis; who says, “It is much more convenient for drawing than pen and ink, because the marks made with it appear distinct upon a white ground, also, in consequence of its brightness, show themselves on black, and can be preserved or rubbed out at pleasure. This mineral is smooth, appears greasy to the touch, and has a leaden-colour, which it communicates with a metallic brightness. It can resist, for a long time, the strongest fire, and even from it requires more hardness; it has, in consequence, been thought to be a species of _talc_. This, in the arts to which it is applied, is a property which greatly enhanceth its value, being manufactured into crucibles, &c., with clay. These vessels are capable of enduring the strongest heat of a chemical furnace.”

Sometimes this lead is foliaceous, and may be crumbled into small pieces or scales; but frequently found denser and more strong. This latter is what writing pencils should be made of; but the former being more frequently found, and, also, coming from the refuse of the workmen, is too often mixed up with some glutinous substance, and there is every reason to suppose it to be enclosed in the groove in a plastic state; these pencils are commonly hawked about our streets by pedlars and Jews; of purchasing which people should be cautious, as they are, in general, utterly worthless.

Robinson, in his Essay towards a natural History of Westmoreland and Cumberland states, that, at first, the country people round Keswick marked their sheep with black-lead. Afterwards, they discovered the art of employing it in their earthenware, and also to preserve iron from rust. The same writer says, the Dutch use it in dyeing, to render black more durable; and that they buy it in large quantities for that purpose. But their application of it for dyeing, we should consider as highly questionable.

The mode of eradicating black-lead by means of an elastic gum, called caoutchouc, or, Indian-rubber, was, we have been informed, first discovered in England somewhere about sixty years ago.

COLOURED GLASS.

The manufacture of glass we find was quite common in Ethiopia, Syria, Assyria, and other Eastern countries, in the earliest ages of the world, as Diodorus Siculus informs us, who says, the Ethiopians enclosed in glass, the bodies of their parents and friends; we doubt, however, that on this point, the historian was deceived. But it really appears probable that soon after the art of making glass was discovered, the idea of communicating to it some colours would easily present itself. This probability appears increased, when it is recollected that much care is requisite to render glass perfectly colourless. As the various metallic particles with which stone and sand abound, (these being the chief ingredients of which glass is composed, and which gradually give tints in fusion,) will almost unavoidably communicate some hue or other, therefore the perfection of glass is to have it perfectly colourless.

But with respect to coloured glass; so frequently have people been imposed upon by having coloured glass sold to them for valuable stones, that some conscientious authors have very laudably and carefully abstained from lending the benefit of instruction in its manufacture, by publishing the method.

The Egyptian artists were so famous in the manufacture of glass, that the Romans were content to receive this article from the glass-houses in Alexandria, and did not interfere in endeavouring to procure the art themselves, until the latter part of the empire.

We read that an Egyptian priest made a present to the Emperor Adrian of several beautiful glass cups, which sparkled with many colours; and such value did that august personage place upon these toys, that he ordered them to be used only on high feasts and solemnities.

Strabo relates, that a glass manufacturer of Alexandria informed him that an earth was found in Egypt, without which the valuable coloured glass could not be made. It has been thought by some, the glass earth here meant was a mineral alkali which was readily found in Egypt, serving to make glass; but this author speaking expressly of coloured glass, it has been suggested as probable, the alkali above named could not have reference to what the artisan intended to imply, but that it must be referred to some metallic earth or manganese.

One Democritus is named by Seneca, as having discovered an art of making artificial emeralds; but it has been conjectured that what the philosopher meant was the art of communicating colour to natural rock crystal, or colouring glass already made, so as to resemble stones, which is a process performed by cementation. Directions have been furnished for this purpose by Porta, Neri, and others; but it is discovered that the articles so coloured are liable to such accidents in the process, that it is next to impossible to render things of any size tolerably perfect, so as to bear cutting afterwards.

In the Museum Victorium at Rome, there are shown a chrysolite and an emerald, both perfectly well executed, and thoroughly transparent, without a blemish.

We have not from the ancients an account of what process they employed; but it must be evident that nothing less than metallic calces could have been used; and for this evident reason, that any other substance could not have resisted the influence of the necessary heat. The last century has, however, produced certain artists in northern European nations, who have adopted a method of employing the precious metals, to communicate a tincture to glass in the process of making, where iron, &c. were originally only used; and their endeavours have been attended with singular success.

By means of an amalgam of gold, or a solution in _aqua regia_, and precipitated with a solution of tin, the metal then assuming the appearance of a rich purple coloured powder; so prepared, it is mixed with the best _frit_, and then called the precipitate or gold calx of Cassius, the inventor of gold purple, or mineral purple.

This precipitate communicates a rich ruby coloured purple, so perfect that it is impossible to discover the deception, without the substances be tried by the usual means--cut with a diamond or a prepared file.

We have had in England some very eminent artists in the practice of staining glass, and also for making artificial representations of various precious stones.

Although the professed object of alchemy has now met with that contempt it merited--because, notwithstanding the immense sums which have been expended, the time lost, and unprofitable labour employed in the unavailing search after what probably never will be found--yet the labour lost and money expended has not been totally useless, since it has served to open the seals which secured chemical science to the modern world; and which is the chief, if not the sole advantage it can claim over antiquity for superiority of information.

Painting on glass, but, perhaps, staining had been a more appropriate expression, or, properly speaking, in enamel, with the preparations for colouring in mosaic work, may, to a certain extent, be justly considered as branches of the art of colouring glass; in all which there is no colour more difficult to be attained than a beautiful red; it now is, and ever has been, most difficult, consequently the dearest colour. The presumed ignorance of ancient artists in preparing this colour has afforded some reason, it is said, to suppose the ancients knew of no other substance proper for that purpose but calx of iron, or manganese. To this we may reply, many specimens are found which show they were not so ignorant in that art, and that it is more than probable the same jealousy which is found to exist in modern days among artizans might prevent our sagacious predecessors from publishing the secrets of their respective professions to the world. We contend, that as the materials must then have had existence, which have been since so successfully employed, pray what was the reason the ancients should not avail themselves of their benefit? In all the higher speculations of science and arts, where the great and superior energies of genius were requisite, this perfection in the ancients far surpassed any exertions which have been since achieved by the moderns. To instance one artist and one art solely, we name the great Praxiteles, so famous in the art of statuary, whose works were a model of perfection.

ETCHING ON GLASS AND GLASS CUTTING.

Without entering into the history of the lapidary’s art, we only propose to speak of those things which ancient and modern authors have said upon the art of engraving on glass, observing, that it was an art anciently known to both the Greeks and Romans; although it appears extremely probable, that from their expressed ignorance of many of those properties which modern chemistry has discovered to belong to matter, they were ignorant of the art of etching on glass.

From antique specimens still preserved, a doubt cannot for a moment be suffered to exist on our minds, but that the art of engraving upon glass was familiar to the Greek artists, who formed upon glass both linear figures, and in relievo, by the same means as are now employed for nearly the same purpose, if we can place any confidence in an able and learned lapidary, Natter, who has established, that the ancients employed the same kind of instruments for this purpose, or nearly such as are now in use; abating, perhaps the use of diamonds, and the dust of that precious material, for which it is conceived they used emery powder, and the dust of glass.

From what is related by Pliny, it certainly appears that they used the lapidary’s wheel, an instrument moving in a horizontal direction over the work-table.

Some have thought that drinking cups and vessels may have been formed from the glass whilst in a state of fusion, by means of this wheel; to this they think those words of Martial refer, where he says, _calices audaces_, having reference to the boldness of the artisan’s touch; those vessels he was constructing often broke under the last touch he bestowed upon his transparent labours, although, perhaps, of costly value; these accidents must of necessity have rendered those articles extremely expensive.

There are not wanting many who affirm the art of glass-cutting, with the instruments necessary for that operation, to be of modern invention. Those assign it to the ingenuity of Caspar Lehmann, originally an engraver on iron and steel, and who, as Beckmann informs us, made an attempt, which succeeded, in cutting crystal, and afterwards glass in the same manner. This artist, we are told, was in the service of Rodolphus, the second emperor of that name, who, in the year 1609, besides giving him valuable presents, conferred on him the title of lapidary and glass-cutter to his court, and gave him a patent, allowing him the exclusive privilege of exercising this new art. He worked at Prague, where he had an assistant of the name of Zacharias Belzer; but George Schwanhard, one of his pupils, carried on the business to a much larger extent. The last named was a son of Hans Schwanhard, a joiner at Rothenburg, and was born in 1601; at the age of seventeen he went to Prague, to learn the art of cutting glass from Lehmann. His good behaviour won so much upon the affections of his master, that on his death in the year 1622, he left him his heir. Schwanhard succeeded in obtaining a continuation of the patent from the emperor, and removed to Nuremburg, where he wrought for many of the nobility of that district. This was, we believe, the occasion of that city claiming the honour of being the birth-place of this new art. In the year 1652, he worked at Prague, and also at Ratisbon, by command of the Emperor Ferdinand III.; and he died in 1676. He left two sons, who both followed the lucrative employment of their father. Afterwards Nuremburg produced many expert masters in the art, who, from the improvement in the tools, and also from discovering more economical modes of using them, were enabled to execute the orders of the public at a more moderate rate than had been previously charged for some articles. Those latter masters likewise brought this art to a much greater degree of perfection. Notwithstanding Zahn was of the same country, and must have been apprised of the facts previously stated, yet he mentions it as a very recent invention at Nuremberg, at the time he published his “Oculus Artificial.” He also furnishes a plate, giving at the same time a description of the various instruments employed. However, that this invention is not purely _novel_, may be perceived from those facts we have already submitted.

It should be stated that before this latter re-introduction, artists used, with a diamond, to cut figures upon glass in almost every form, as far as the representation by lines went. The history of diamonds has been presented to the public by Mr. Mawe, in his observations on the diamond districts of Brazil. It appears to be yet undetermined whether the ancients used that stone for the purpose of cutting others; upon this point Pliny appears to be satisfied that they did.

Solinus and Isidore both express themselves in a manner the reverse. But although this may leave us in some doubt, it appears pretty clear that they did not attempt to cut that valuable production with its own dust, or to give it different faces, or render it more brilliant by the same means. If this point was settled, there could be no great difficulty in affirming or negativing the fact of their engraving upon that stone. Thus doubts appear to increase on this head, for Mariette denies that they did; Natter appears uncertain; and Klotz asserts with confidence it was certain. His authority, to be sure, has been considered not to be of much weight.

The proper question, however, appears to be, whether the Greeks and Romans used diamonds for cutting and engraving other stones or glass. Natter, in his work already noticed, thinks they were employed on some antique engravings. His authority is deserving respect. But if they were employed on other stones, the authority which at present directs us, confidently alleges they did not employ them in cutting glass; but he points out the mode in which that article was wont to be divided, in the following terms: “They used for that purpose emery, sharp-pointed instruments of the hardest steel, and a red-hot iron, by which they directed the rents at their pleasure.”

The first mention which appears to occur of the use of the diamond for this purpose, is recorded of Francis I. of France, who, fond of the arts, sciences, and new inventions, wrote a couple of lines with a diamond, on a pane of glass in the Castle of Chambord, to let Anne de Pisseleu, Duchess of Estampes, know that he was jealous.

About 1652, festoons and other ornaments, cut with a diamond, were made on Venetian glasses; then considered the best. Schwanhard was a professed adept in that art; and since his time an artist of the name of John Rost, of Augsburg, cut some drinking glasses, which were purchased by the Emperor Charles VI., at an extravagant price.

ETCHING ON GLASS.

An acid to dissolve siliceous earth was discovered as late as 1771, by the celebrated chemist Scheele, in _sparry fluor_. It is conceived that this cannot be of older date than that period; but it is alleged that an acid was discovered as early as the year 1670, by Henry Schwanhard. It being said that some aquafortis had dropped, by accident upon his spectacles, the glass being corroded by it, he thence learned to improve the liquid that he could etch figures and write upon glass. How he prepared this liquid is a secret which has not been revealed. The _Teutsche Akedemie_ says on this subject, that he, by the acuteness of his genius, proved that which had been considered impossible could be accomplished; and found out a corrosive so powerful that the hardest crystal glass, which had hitherto withstood the force of the strongest spirits, was obliged to yield to it, as well as metals and stones. By these means he delineated and etched, on glass, figures of men, in various situations, animals and plants, in a manner perfectly natural, and brought them to the highest perfection.

The glass proposed to be etched is made perfectly clean and free from grease; then the figure is covered with a varnish; then an edge of wax being raised round the glass, the acid is poured in, and the whole ground on the exterior of the figures appears rough, whilst the figure is preserved in its original beauty of outline, bright and smooth. This is the mode the inventor adopted.

Professor Beckmann says, he mentioned this ancient method of etching upon glass, to an artist of the name of Klindworth, who possessed great dexterity in such arts, and requested him to try it; he drew a tree with oil varnish and colours on a plate of glass, applied the acid on the plate in the usual manner; after it had been upon the plate for a sufficient time, poured off, and the plate afterwards cleaned of the varnish, a beautiful tree was left bright and smooth, with a rough back-ground. It is conceived that many great improvements may yet be made in this process.

It appears that no other acid than that produced by the sparry fluor is capable of corroding every kind of glass, though Baume, in his “Chemique Experimentale,” says, that many kinds of glass may be corroded by the marine and vitriolic acids.

In this state of uncertainty was the public mind till the year 1725, when it was thought that a recipe, older than that previously mentioned, might possibly be discovered. Accordingly, in that year, in the month of January, the following is said to have been transmitted to the publisher of the “Œkonomische Encyclopedie,” by Dr. John George Weygand, of Goldingen, which is reported to have belonged to Dr. Matthew Pauli, of Dresden, then deceased; with which the last named gentleman had etched, on glass, arms, landscapes, and figures of various kinds. We find, that in it, very strong acid of nitre was used, which entirely disengages the acid of sparry fluor, though the vitriolic acid has been commonly employed, and figures thus produced will appear as if raised above the plane of the glass.

This sparry fluor is found abundantly in Derbyshire, as well as in the mines of Germany. Theophrastus is the first who notices the effect of sparry fluor, by observing that there are certain stones which, when added to silver, copper, and iron ores, become fluid. It appears that Cronstedt was the first systematic writer who gave it a name.

When _spiritus nitri per distillationem_ has passed into the recipient, ply it with a strong fire, and when well dephlegmated, pour it, (as it corrodes ordinary glass,) into a Waldenburg flask; then throw into it a pulverised green Bohemian emerald, otherwise called _hesphorus_, (which, when reduced to powder and heated, emits in the dark a green light,) and place it in warm sand for twenty-four hours. Take a piece of glass, well cleaned, and freed from all grease by means of a ley; put a border of wax round it, about an inch in height, and cover it equally all over with the above acid. The longer you let it stand, so much the better; and at the end of some time the glass will be corroded, and the figures which have been traced out with sulphur and oil varnish will appear as if raised above the plane of the glass.

HYDROMETERS.

The Hydrometer is an instrument for admeasuring liquids; by it the strength or specific gravity of different fluids is discovered, by the depth to which it sinks in them. It has been chiefly used for discovering the contents of different salt waters, without analysis, and is now almost entirely used by persons connected with the spirit-trade, to ascertain the different degrees of strength, and what alloy they will bear; hence its utility to the manufacturer and the excise-officer is apparent.

The laws respecting the comparative weight of different fluids, as well as of solid bodies immersed in them, was first discovered by that great geometrician Archimedes. It may be far from improbable that Archimedes constructed that instrument himself; and if it should appear that he did, it must have happened two hundred and twelve years before the Christian era.

The most ancient mention of this instrument by its specific name, occurs in the fifth century of our era, upon the following occasion. The anecdote is very singular and affecting, and also evinces the incapacity of humanity to act consistent and as it ought, when we suffer ourselves to be directed by passions unworthy of the human character.

It is first discovered in those letters of Synesius to the philosophic and beautiful Hypatia. We trust we may be excused the liberty we propose to take in detailing this circumstance, which is comparatively little known; and as its interest also recommends it, this furnishes an additional motive.

Hypatia was the daughter of Theon, an eminent mathematician of Alexandria, some of whose writings are still extant. By her father she was instructed in the mathematics, and from other great men, who at that period abounded in Alexandria, she learned the Platonic and Aristotelian philosophy, and acquired such a knowledge of these sciences, that she taught them publicly, with the greatest applause. She was young and beautiful, had a personable figure, was sprightly and agreeable in conversation, though, at the same time, modest; and she possessed the most rigid virtue, which was proof against every temptation. She conducted herself with so much propriety towards her lovers, that they never could obtain more than the pleasure of her company, and hearing her discourse; and with this, which they considered as an honour, they were contented. Those who were so daring as to desire further communion she dismissed; and even destroyed the appetite of one of her admirers, who would not suffer her to philosophise, by means of some strong preparation, which others appear not to have since imitated.

She suffered so cruel a death, that had she been a Christian, and suffered from Pagan error, her name would have been ranked among its most honoured victims in the list of martyrology; but being a Pagan, and suffering from the persecution of superstitious and anti-Christian zeal, she is honoured among the foremost of martyrs to celestial philosophy.

The name of the Christian patriarch, at that period in Alexandria, was Cyrill, whose family had, for upwards of a hundred years before his time, produced bishops, who had been much more serviceable to their own family connections than they had ever been towards the propagation of the Christian faith. The present was proud, litigious, and revengeful, vindictive and intolerant to the last degree; his ignorance debasing his own character as a man, and scandalising the religion of which he was so unworthy a minister. He stupidly conceived himself sanctioned in everything which his foolish and mistaken ideas might dictate to be for the glory of God, and acted as a persecutor, prosecutor, judge, and executioner: he had condemned Nestorias without hearing his defence. As the city of Alexandria was then very flourishing on account of its extended commerce, the emperor had there allowed greater toleration and more peculiar privileges to all religions, than in any other place: it consequently contained, among others, a great number of Jews, who carried on a most extensive trade, as well as a great many Pagan families. In the eyes of the bigot Cyrill this was wrong; he would have the sheep-fold clean, and the Jews must be banished. The governor, however, who was a man of prudence and sober discretion, much better acquainted with the real interests of the city, opposed a measure he saw replete with mischief, and even caused to be condemned to death a Christian profligate, who had injured the Jews. This malefactor was, by the express order of Cyrill, buried in the church as a martyr; and he collected an army of five hundred lazy monks, who abused the governor in the public streets, and excited an insurrection among the people against the Jews, so that the debased race of Abraham was expelled from the city where they had so long existed unmolested from the time of Alexander the Great.

Cyrill, one day, whilst looking for objects of persecution, saw a number of carriages, attended with servants, belonging to the first families in the city, before a certain house. Inquiring what was the cause of the assembly, he was informed that it was the habitation of the lovely Hypatia, who, on account of her extensive learning and very eminent talents, was visited by people of the first respectability. This afforded to the malignant priest a sufficient object for the exercise of his jealousy against the meritorious, the unoffending, the beautiful Hypatia. He from that moment resolved upon her destruction. Accordingly he lost no time in exciting his myrmidons, the monks and priests, those who should have been the ministers of that religion which they professed to teach, to destroy the fair philosopher. They accordingly, with diabolical rage, and instigated by infernal cruelty, took the earliest opportunity to seize her, hurried her to the church--the temple of peace and good-will--which they violated by an offence at which humanity must shudder; having torn the clothes from her delicate form, they tore the flesh from her bones with potsherds, then dragged her mangled body about the city, and afterwards burnt it.

This demoniacal tragedy took place in the year 415, and was perpetrated by the professed servants of Him who came into world to save those which were lost--to preach peace and good-will to all men. The impressions which such an event made upon people of every persuasion may be conceived; they admit not of description from a feeble pen: but we may ask the question, was it such a transaction as was calculated to make converts to the doctrines of Christianity?--whose avowed motive and maxim is, in the words of Milton,

“By winning words, to conquer willing hearts,
And make persuasion do the work of fear.”

All historians are not agreed in some circumstances of the preceding relation; but they generally unite in bestowing praise upon Hypatia, whose memory was long honoured by her grateful and affectionate scholars, among whom was Synesius, of a noble Pagan family, who had cultivated philosophy and the mathematics with the utmost ardour, and who had been one of her most intimate friends and followers. On account of his learning and virtues, many eminent talents, and open disposition, the inhabitants of Ptolemais were desirous he should be bishop, having been previously employed on many public and important concerns with success. After modestly desiring, for a long period, that they would fix their choice upon a more worthy object, they still persisting, he assented, upon condition that he was not to believe in the resurrection, to which he could not at that time bring his internal conviction: he suffered himself to be baptised, and became their bishop; he was confirmed by the orthodox patriarch Theophilus, the predecessor of Cyrill, to whose jurisdiction Ptolemais belonged: he afterwards renounced his error respecting the resurrection. This learned man evinced his gratitude to Hypatia, by the honourable mention which he made of her in some of his writings, still preserved.

In his fifteenth letter to her, he tells Hypatia, that he was so unfortunate, or found himself so ill, that he wished to use an hydroscopium (the Greek for hydrometer), and he requests that she would cause one to be constructed for him. He says, “It is a cylindrical tube, of the size of a reed or pipe; a line is drawn upon it lengthways, which is intersected by others, and these point out the weight of water. At the end of the tube is a cone, the base of which is joined to that of the tube, so that they have both only one base. This part of the instrument is called _baryllion_. If it be placed in water, it remains in a perpendicular direction, so that one can readily discover by it the weight of the fluid.”

Petau, who published the works of Synesius, in the year 1640, acknowledges that he did not understand this passage. An old scoliast, he says, who had added some illegible words, thought it was a water-clock; but the ellepsydra was not immersed in water, but filled with it. He therefore thought that it might allude to the chorobates, which Vitruvius describes as an instrument employed in levelling; but it appears that Synesius, who complained of ill health, could have no occasion for such an instrument. Besides, no part of that instrument he describes, has any resemblance to the one described by Synesius.

From the works of Fermat, an excellent mathematician, and a very learned man, well acquainted with antiquities and the works of the ancients, we give the following explanation concerning the hydroscopium of Archimedes, as this article would be incomplete without it:--

“It is impossible,” says he, “that the _hydroscopium_ could be the level or _chorobates_ of Vitruvius, for the lines on the latter were perpendicular to the horizon, whereas the lines on the former were parallel to it. The hydroscopium was undoubtedly a hydrometer of the simplest construction. The tube may be made of copper, and open at the top; but at the other end, which, when used, is the lowest, it must terminate with a cone, the base of which is added to that of the tube. Lengthwise, along the tube, are drawn two lines, which are intersected by others, and the more numerous these divisions are, the instrument will be so much the more correct.--When placed in water it sinks to a certain depth, which will be marked by the cross-lines, and which will be greater, according to the lightness of the water.” A figure which is added, might have been dispensed with. When a common friend of Fermat and Petau showed it to the latter, he considered it to be so just, and explanatory of the real meaning of Synesius, that he wished to be allowed the opportunity of introducing it in a new edition of the works of Synesius.

_FINIS._

J. S. Pratt, Stokesley, Yorkshire.

Transcriber’s Notes

Punctuation, hyphenation, and spelling were made consistent when a predominant preference was found in this book; otherwise they were not changed.

Many typographical errors were corrected; occasional unbalanced quotation marks retained.

Text uses both “Guttenberg” and “Guttenburg”, “Helvelius” and “Hevelius”; both versions retained.

Page 18: “documentary” was printed as “documentry”; changed here.

Page 33: “transcendant” was printed that way.

Page 33: The opening quotation mark preceding “A complete Course of Lithography” was added by Transcriber. Other punctuation and spelling within that title has not been changed, but some of it differs from what was printed in the English translation of the cited book.

Page 54: The period after “Deity” in “offensive to the Deity. that the great majority” probably should be a semi-colon.

Pages 63 and 249: A question mark is followed by a lower-case word.

Page 109: “Chardiu” was printed that way.

Page 139: “It last it changed colours” should begin with “At”.

Page 171: “the bull of Æolus” probably is a misprint for “ball”.