and, like these roots, yams often prove an excellent preparatory crop for wheat. Farther, they are very productive; so that the red variety yields, in general, 12 tons per acre: the white sort is less fruitful; but, being more delicate, it is chiefly raised for the table, in the West Indies.
The culture of these bulbous roots in Britain is, at present, we understand, confined to the counties of Mid-Lothian and Stirling; where they are given to cows; the milk of which is thus considerably increased, without affecting its quality or flavour.
As an article of food, the yam possesses similar properties with the potatoe, excepting that it is less mealy. in a raw state, it is viscous; but, when roasted, this bulbous root is equally wholesome and nourishing, so that the inhabitants of the West Indies prefer it even to bread. In some respects, therefore, yams are more valuable than potatoes; because the former are much lighter, and more easily digested:—when first dug out of the ground, then dried in the sun, and preserved from humidity, in casks full of dry sand, they may be kept for several years, uninjured by frost, and without losing any part of their nutritive quality.—These beneficial roots may also be peeled, deprived of their moisture by pressure, and dried in the same manner as Mr. Millington directs potatoes to be preserved (see vol. iii. p. 438). In this manner, yams may be packed in casks, like flour, and imported in a perfectly sound state, from the West Indies: when grated, and mixed with wheaten or barley-flour, they may be formed into a light and salubrious bread. Nor are they less nourishing, when converted into pottage, or pudding, with the addition of milk. Thus, Mr. R. Pearson ("Annals of Agriculture," vol. 35), informs us, that the meal, obtained from the boiled and grated roots, when beaten up with milk and eggs, without any flour, yielded a firm and well-flavoured dish; which could with difficulty be distinguished from a common batter-pudding. By this treatment, the yams are divested of their saccharine taste, which renders them at first disagreeable to some persons; though such property is, on the whole, of considerable use; as it saves the expence of sugar.
YARD, is a measure of length, employed for measuring cloth, stuffs, &c.
The English yard contains three feet, or 36 inches: it is converted into ells English, by subtracting a fifth part, or 7 one-5th inches; and into ells Flemish, by adding one-eighth, or 412 inches.
YARN, in general, denotes the manufacture of wool, hemp, flax, cotton, &c. converted into filaments or threads, which are subservient to a variety of useful purposes.
Formerly, all yarn was spun or twisted by means of the distaff, or wheel; but lately, both the ingenuity of mechanics, and the powers of machinery, have been called in aid (see the articles Cotton, and Spinning), to facilitate that operation; and, in June, 1787, Messrs. John Kendrew and Thomas Porthouse, obtained a patent for their invention of a machine, upon new principles, designed to spin yarn from hemp, tow, flax, or wool.—As this privilege is now expired; and such contrivance promises to be very useful in the woollen as well as other manufactures,
