The raw silk, imported in the state in which it is wound from the cocoons, has to be twisted into thread, after being dyed, so as to approach the stage of yarn in the cotton manufacture. This twisting is technically called throwing, and is one of the departments in which the greatest improvements have been introduced, as shown by silk throwers from Macclesfield in the machine department of the Great Exhibition; and, by the improvements, the cost of throwing, or twisting, has been reduced from 10s. per lb. to 3s. It takes about twelve pounds of cocoons to make one pound of reeled silk, and that pound will produce from fourteen to sixteen yards of gros de Naples. Many attempts have been made to naturalize the silk-worm in this country, but, after rather large sums have been expended on it, it is now quite clear that, although it be possible to obtain large quantities of silk of a certain quality, the undertaking cannot be made to pay: the climate is an obstacle. For centuries the silk-worm was only known to the Chinese,--the Greeks and Romans used the substance without knowing from what it was produced or whence it came. In the sixth century, in the reign of Justinian, the eggs of the silk-worm were brought secretly to Constantinople from China by the Nestorian monks in a hollow cane, hatched, and successfully propagated. For six centuries the breeding of silk-worms was confined to the Greeks of the Lower Empire. In the twelfth century the art was transferred to Sicily, and thence successively to Italy, Spain, and France. Great efforts were made in the reign of James I. to promote the rearing of silk-worms in England, and mulberry trees were distributed to persons of influence through many counties. The scheme failed. But in 1718 a company was incorporated, with a like purpose, and planted trees, and erected buildings in Chelsea Park. This scheme also failed. Great efforts were made to plant the growth of silk in the American colonies, and the brilliant prospects of establishing a new staple of export formed a prominent feature in the schemes for American colonization, of which so many were launched in the beginning of the eighteenth century. But up to the present time no progress has been made in it in that country, although silk-worms are found in a natural state in the forests of the Union. Indeed, it seems a pursuit which needs cheap attentive labour as well as suitable climate. Some attempts have been made in Australia, but there again the latter question presents an insurmountable obstacle. If the mulberry would thrive in Natal, where native labour is cheap, it would be worth trying there, although we cannot do better than develop the resources of the silk-growing districts of India, where the culture has been successfully carried on for centuries.