Five species of elm are now grown in Britain: - The common rough-leaved (Z7. campestris) is frequent in scattered woods and hedges in S. England, and in France and Spain, attaining 70-80 ft. high, and 4 ft. diam. Its wood is harder and more durable than the other kinds, and is preferred for coffins, resisting moisture well. The corked-barked (U. suberosa) is common in Sussex, but the wood is inferior. The broad-leaved wych-elm or wych-hazel (U. montana) is most cultivated in Scotland and Ireland, reaching 70-80 ft. high and 3-4 1/2 ft. diam. The smooth-leaved wych-elm (U. glabra) is abundant in Essex, Hertford, the N. and N.-E. counties of England, and in Scotland, growing to a large size. The wood is tough and flexible, and preferred for wheel-naves. The Dutch elm (U. major), the smallest of the five, is indigenous to Holland; its wood is very inferior. Elm-trunks average 44 ft. long and 32 in. diam. The wood is very durable when perfectly dry or constantly wet. It is not useful for general building, but makes excellent piles, and is used in wet foundations, waterworks, and pumps; also for wheel-naves, blocks, keels, and gunwales.

It twists and warps in drying, shrinks considerably, and is difficult to work; but is not liable to split, and bears the driving of bolts and nails very well. Its weight is 34-50 lb. a cub. ft.; cohesive force, 6070-13,200 lb.; strength, 82; stiffness, 78; toughness, 86. The colour of the heartwood is a reddish-brown. The sapwood is yellowish- or brownish-white, with pores inclined to red. The medullary rays are not visible. The wood is porous and very twisted in grain; is very strong across the grain; bears driving nails very well; is very fibrous, dense, and tough, and offers a great resistance to crushing. It has a peculiar odour, and is very durable if kept constantly under water or constantly dry, but will not bear alternations of wet and dry. Is subject to attacks of worms. None but fresh-cut logs should be used, for after exposure, they become covered with yellow doaty spots, and decay will bo found to have set in. The wood warps very much on account of the irregularity of its fibre. For this reason it should be used in large scantling, or smaller pieces should be cut just before they are required; for the 6ame reason it is difficult to work. The sapwood withstands decay as well as the heart. Elm timber should bo stored under water to prevent decay.

Three species of elm are indigenous to N. America, and have similar uses to the European kinds: - The common American (U. americana) grows in low woods from New England to Canada, reaching 80-100 ft. high; its wood is inferior to English. The Canada rock or mountain (U.racemosa) is common to Canada and the N. States; the wood is used in boat-building, but is very liable to shrink, and gets shaky by exposure to sun and wind; its weight is 47-55 lb. a cub. ft. The slippery (U.fulva) gives an inferior wood, though much used for various purposes. Quebec elm is valued at 4-5Z. a load.