142 LECTURE XVI. 



separated from the seeds by means of rollers, between which it passes, and 

 leaves the seeds behind. It is then beaten, on a flake, or a stool covered 

 with a texture of cord. Next, it is carded, either by hand, the fibres 

 being drawn into regular order by cards, that is, by brushes of fine pointed 

 wire; or, more commonly, by machinery, the cards being disposed in 

 cylinders which revolve nearly in contact with each other. The drawing 

 or roving machine then draws it into long flakes, a state preparatory to 

 its being spun by Sir Richard Arkwright's machines or jennies, which 

 form at once forty threads by the labour of one person. 



The silkworm is bred in the greatest abundance in Italy and in Asia ; 

 it has lately been introduced very successfully into the British possessions 

 in the East Indies. The principal food of the caterpillar is the white 

 mulberry tree, which is too delicate to thrive well in northern climates : in 

 Italy the trees are planted in beds, like willows, and the foliage is cut as 

 it is wanted. The room in which the worms are fed, is kept at the tem- 

 perature of 80 degrees of Fahrenheit. The eggs of a former year are 

 hatched either by animal heat, or by that of the sun ; at the age of six 

 weeks, the caterpillars begin to spin, first a light external texture, which is 

 carded and spun for coarse silk, and afterwards a compact oval pod or 

 cocoon, of one continued thread. The threads of several cocoons are 

 reeled off at the same time : for this purpose they are generally put into 

 warm water, which kills the chrysalis : but when it is preserved, it soon 

 turns to a moth, which lives but a few -days, taking no food, and dies after 

 producing eggs for the next season. 



The silk is either yellow or white, but the white is an accidental variety 

 only. By repeated washings, the yellow silk is bleached, and that which 

 is originally white, acquires a more perfect whiteness. Soap is also used 

 for removing a gummy substance that accompanies the silk of the cocoons. 



Wool is distinguished into two principal varieties, long and short wool. 

 The longest is from Lincolnshire ; it is combed, by means of instruments 

 furnished with a double row of long and sharp teeth of iron or steel ; it is 

 repeatedly drawn from one comb to the other, heat being used in the pro- 

 cess, and also a little oil. The fleeces of long wool are generally heavier 

 than those of short wool, but less valuable on account of their coarseness ; 

 they are used for worsteds, and for cloths in which the separate threads 

 remain visible, as stuffs, shalloons, serges, and tammies. Short wool, on 

 the contrary, is carded, and is used for cloths in which the individual 

 threads are concealed by the projecting fibres. 



The principal use of thread and yarn, when spun, is for the purpose of 

 weaving. The same force of lateral adhesion that retains the twisted 

 fibres of each thread in their situations, is here also employed in giving 

 firmness to the cloth ; and this adhesion is generally increased by the 

 action of any external force, tending to strain the whole texture. 



The first step in weaving is to form a warp, which consists of threads 

 placed side by side, continued through the length of the piece, and suffi- 

 cient in number to constitute its breadth. This being wound on a beam 

 or roller, in the loom, the threads are drawn through a harness, consisting 

 of loops formed by twine fixed to bars or frames, which elevates and 



