1154 WO AD 



of steel wire and of steel -wire-rope renders it much more supple, and less liable to 

 injury through being bent over a drum. A steel rope easily straightens of itself after 

 being bent oven to a small angle, which is not the case with iron wire-rope. The 

 duration of all ropes is very greatly influenced by the many bondings to and fro 

 to which thoy are subjected, and these influences are intensified by corrosion. Both 

 the mechanical and the chemical sources of deterioration act in a less degree on steel 

 wire, as it is stronger, and is, at the same time, less subject to corrosion, as the 

 carbon it contains, however slight, greatly impedes the action of rust. It has been 

 proved that wire-rope which is made of soft annealed wire cannot stand one-quarter 

 or one-sixth of the bending to and fro that it can stand if made of the same wire after 

 it has been hardened. It is to be noticed that, although it can matter but little as 

 regards absolute length whether a wire-rope elongates or takes a permanent set, in 

 practice this is not the case as to its cross-section or the arrangement of its strands, 

 which is injured if the material too easily takes a permanent set. It is easy to imagine 

 cases in which this very softness and ductility is cf great value. In the same way wo 

 should imagine that the best pianoforte-wire ought to have a certain elastic limit 

 or a limit up to which it will elongate temporarily without taking a permanent 

 set, and a certain amount of ductility or power of elongation without rupture, while 

 it should have a certain ultimate breaking strength. The same is the case with the 

 other many applications of wire; most of which, however, will be best suited by 

 a high limit of elasticity, or the power of elongating temporarily without taking a 

 permanent set. The principal seat of the iron wire manufacture in England is 

 Birmingham. The most important improvement to be looked for in the wire manu- 

 facture is some easy and cheap means of drawing very long lengths of wire. 



WO AD (CHiede, Pastel, Fr. ; Waid, Ger. ; Guado, It.), the Isatis tinctoria, Linn., 

 is almost the only plant growing in the temperate zone which is known to produce 

 indigo. It is an herbaceous, biennial plant, belonging to the natural order Cruciferce, 

 and boars yellow flowers and large flattened seed-vessels, which are often streaked with 

 purple. The leaves, which are the only part of the plant employed in dyeing, are 

 large, smooth, and glaucous, like cabbage-leaves, but exhibit no external indication 

 of the presence of any blue colouring-matter, which indeed, according to modern 

 researches, is not contained in them ready formed. The plant called by the Romans 

 glastum, with which, according to Pliny, the Britons, dyed their skins blue, is sup- 

 posed to be identical with woad. Before the introduction of indigo into the dye-houses 

 of Europe, woad was generally used for dyeing blue, and was extensively cultivated in 

 various districts of Europe, such as Thuringia,. in Germany ; Languedoc, in Franco ; 

 and Piedmont, in Italy. To these districts its cultivation was a source of great 

 wealth. Beruni, a rich woad manufacturer of Toulouse, became surety for the pay- 

 ment of the ransom of his king, Francis I., then a prisoner of Charles V., in Spain. 

 The term Pays de cocalgne, denoting a land of great wealth and fertility, is indeed 

 supposed to be derived from the circumstance that the woad balls, called in French 

 cocaignes, were manufactured chiefly in Languedoc. 



The woad-leaves were not employed by the dyer in their crude state, but were 

 previously subjected to a process of fermentation, for the purpose of eliminating the 

 colouring-matter. The seed having been sown in winter, or early spring, the 

 plants were allowed to grow until the leaves were about a span long, and had assumed 

 the rich glaucous appearance indicative of maturity, when they were stripped or cut 

 off. The cropping was repeated several times, at intervals of five or six weeks, until 

 the approach of winter put a stop to the growth of the plant. The leaves set up in 

 the succeeding spring yielded only an inferior article (called in German Kompso- 

 waid), and it was therefore customary to keep only as many plants until the following 

 year as were required for obtaining seed, which, the plant being biennial, is only 

 produced in the second year. The leaves, after being gathered, were slightly dried, 

 and then ground in a mill to a paste. In Germany it was usual to lay this paste into 

 a heap for about twenty-four hours, and then form it by hand into largo balls, which 

 were first dried partially in the sun, on lattice-work or rushes, and then piled up 

 in heaps a yard high, in an airy place, but under cover, when they diminished in 

 Size and became hard. These balls, when of good quality, exhibited, on being 

 broken, a light blue or sea-green colour. They are usually sold in this state to 

 manufacturers, by whom they were subjected to a second process in order to render 

 them fit for the use of the dyer. This process was conducted in the following 

 manner : The woad balls were first broken by means of wooden hammers, and the 

 triturated mass was heaped up on a wooden floor, sprinkled with water, sometimes 

 with a little wine, and allowed to ferment or putrefy. The mass became very hot, 

 and emitted a strong ammoniacal odour, and much vapour. In order to regulate the 

 process, it was frequently turned over with shovels, ind again sprinkled with water. 

 When the heat had subsided, the mass, which had become dry, was pounded, passed 



