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tlioiigh it h« only about half the quantity oF goM Or fiKfr 

 ai tint made amoii); us, looks far moi-e beautiful. The 

 flatted wire is neither wound ciofe together on the lilk 

 threads, nor the threads ftruck clofe in the weaving ; yet, by 

 paffiig the Huff betwixt rolls, the difpofition and manage- 

 njent of which is kept a fecret, the tiffuc or flower is made 

 to appear one entire brilliant plate of gold or filver. The 

 French minillry judged this manufaclure important enough 

 to dcferve their attention ; and accordingly, for contriving 

 the machinery-, tliey engaged the in renlous M. Vaucanfon, 

 known throughout Europe for his curious pieces of mechau- 

 ifm, who, in the memoirs of the academy for the year 1737, 

 gives an account of his fuccefs, and of the eftablifliment of 

 fueh a manufadlure at Lyons. 



The lower roll is made of wood, thirty-two inches in 

 length and fourteen in diameter ; the upper one of copper, 

 thirty-fix inches long and eight in diameter : this lall is hol- 

 \n\v, and open atone end, for introducing iron heaters. I'or 

 making the rolls cylindrical, he has a particular kind of lathe, 

 wherein the cutting tool, which the molt dexterous hand 

 could not guide in a (Iraight line through fuch a length as 

 lliirty-fix inches, is made to (liJe, by means of a fciew, on 

 two large (leel rulers, pcrfeclly (Iraight, and capable of be- 

 ing moved at pleafure, uearcf, and always esaclly parallel, 

 to the axis of the roll. 



He firll difpofcd the rolls nearly as in the common flatting 

 mill. Ill this difpofition, tin men were fcarcely lufHcient for 

 turning them with force enough to duly extend the gilding ; 

 a:i! the collars, in which the axes of the rolls turned at each 

 cud, wore or gulled fo fall, that the prcffure continually 

 diminilhed, infomuch that a piece of ftuff of ten ells had the 

 gilding fenfibly lefs extended on the lad part than on the firft. 

 He endeavoured to obviate this inconvenience by fcrewing 

 tlic rolls clofer and clofer in proportion as the ItufF pafled 

 through, or as the wearing of the collars occafioned more 

 play between them ; but this method produced an imper- 

 fedion in the fluff, ever)' turn of the fcrew making a fenfible 

 bar acrofs it. To lelTen the attrition, each end of the axes, 

 inftead of a collar, was made to turn between three iron cy- 

 linders called friftion-wheels : but even this did not anfwer 

 fully, for now another fource of unequal preffure was difco- 

 vcred. The wooden roll, being compreffible, had its diame- 

 ter fenfibly diminiflied : it likevvife loll its roundnefs, fo that 

 the prelTure varied in different points of its revolution. On 

 trying different kinds both of European and Indian woods, 

 ell the hard ones fplit, the foft ones warped without fplitting, 

 and, of more than twenty rolls, there was not one which con- 

 tinued round for twenty-four hours even without being 

 worked in the machine. 



Thefe failures put him upon contriving another method of 

 prelTmg the rolls together, fo that ihc force fhould always 

 accommodate itfelf to whatever inequalities might happen. 

 The axis of the copper roll being made to turn between 

 friftion wheels as before, that of the wooden one it prcfTed 

 upwards by a lever at each end furnilhed with a half collar 

 for receiving the ei>d of the axis. Each lever has the end of 

 it.s fliortarm fupported on the frame of the machine, and the 

 long arm is drawn upwards by an iron rod communicating 

 with the end of the fhort arm of another lever placed hori- 

 -.jontally : to the long arm of this lall lever is hung a weight, 

 and the levers are fo proportioned, that a weight of 30 

 pounds prctTcs the rolls together with a force equivalent to 

 1 75 ;?6 pounds, which was found to be the proper force -for 

 the iutTicient cxtenfion of the gilding. By this contrivance 

 four men can turn the rolls with more eafe than ten can 

 turn thole which are kept together by fcrews ; and the fame 

 veight acting uniformly in evtry pan, the preilure continues 



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always equal, though the wooden roll iliould even become 

 oval, and though the Huff be of unequal thicknefs. 



A piece of cloth, of about two ells, is fowed to the begin- 

 ning and end of the fluff, to keep it out to its width when it 

 enters and parts from the rolls, which could not be done by 

 the hands for fear of burning or bruifing them : a^ it would 

 take too mucli time to few thefe cloths to every fmall piece 

 of an ell or two, a number of thefe is fowed together. The 

 llntr is rolled upon a cylinder, which is placed behind the 

 machine, and its axis prefFed down by fprings to keep the 

 fluff tight as it comes off. Four iron bars, made red hot, 

 are introduced into the copper roll, which in half an hour ac- 

 quires the proper degree of heat, or nearly fuch a one as ii 

 ufed for the ironing of linen : the wooden roll is then laid in 

 its place, and the machine fet to work. If more than thirty 

 ells are to be pafTed at once, tlie wooden roll mull be chr.iigod 

 for another, for it will not bear a longer continuance of the 

 heat witiiout danger of fplitting, and therefore the manufac- 

 turer fliould be provided with feveral of thefe rolls, that when 

 one is removed, another may be ready to fupply its rooin : 

 as foon as taken off fro:ii the machine, it (hould be wrapt in 

 cloth and laid in a moill place. 



The principal inconvenience attending the ufe of this ma- 

 chine is, that the heat necefTary for extending the gilding, 

 though it improves the brightnefs of white and yellow filks, 

 is injurious to fome colours, as crimfon and green. A double 

 preffure will not fupply the place of heat : and the only 

 method of preventing this injury, or rendering it as flight as 

 poffible, appeared to be to pafs the fluff through with great 

 celerity. 



Rich brocades may be cleaned, and the luflre of tliem re- 

 covered, by wafhing them with a foft brufli dipped in warm 

 fpirit of wine. 



Neither alkaline liquors nor foap (hould be ufed for this 

 purpofe ; becaufe the former, while they clean the gold, 

 corrode the filk, and change or difcharge its colour, and 

 the hitter alfo alters the fhade, and even the fpecies of certain 

 colours. But fpirit of wine may be ufed without any danger 

 of its injuring either the colour or the quality of the fubjeft, 

 and, in many cafes, it proves as effedlual for reftoring the 

 lullre of the gold, as the corrofive detergents. 



Spirit of wine fcems to be the only material adapted to 

 this intention ; however, this is not proper in all cai^cs : for 

 if the bafe metal, with which the gold of the covering was 

 alloyed, has been corroded by the air, the particles of the 

 gold may thus be difunited ; and the lilver underneath, tar- 

 ni(hed to a yellow hue, may continue a tolerable colour to 

 the white ; but in fuch cafes the removal of the tarnifli would 

 be prejudicial to the colour. See Lewis's Com. Philofo- 

 phico-Technicnm, p. 62. 226. 



Brocadh-Shell, in ConcLoh^y, a trivial name given 

 fometimes to CoNus Geographicus. I^inn. In a more 

 general fenfe, the epithet brocade, fynonymous with the 

 French Irocard, is applied to various other objedts of natu- 

 ral hiftory, whofe difpofition of colours, and markings, bear 

 a fancied refemblance to that fort of fluff, lilk, cloth, and 

 wh-ch is commonly underflood by the word brocade. Bro- 

 card among the French, and brocade with us, is not, there- 

 fore, the language of naturalifls, but of dealers, and un- 

 fcientific collectors. 



BllOCARDICS, Crocakdica, denote maxin^ or prin- 

 ciples in Lo'-m; fuch as thofe pubhflied by Azo, under th« 

 title of Brocard'ua furls. 



VofTms derives the word from the Greek rspix^x*'^' <1- <"• 

 firjl elements. Others, with more probability, from Bur- 

 chard, or Brochard, bifliop of Worms, who made a colle-c- 

 tjon of canons, called from hence BrdCArdha ; and as this 



work 



