560. This species, which is commonly called the "Sweet" or Spanish Chestnut, is supposed to be a native of Greece and Western Asia, but grows wild in Italy, France, and Spain. It is also to be found in the north of Africa and in the woods of North America, but it is said not to be a native of Britain, although grown in the country from a very early period. It is thought by some to have been introduced by the Romans.

Under favourable circumstances of soil and situation the tree often attains in the course of fifty or sixty years a height of 60 or 70 feet, with a stem of from 4 to 6 feet in diameter. The mean size of the trunk or stem, however, according to Hassenfratz, is about 44 feet in length and 37 inches in diameter.

As a tree the chestnut is one of the most long-lived in Europe, sometimes enduring for more than 1000 years; but unlike oak, which gains strength and durability by age, after it arrives at about the age of fifty years it begins to deteriorate at the heart, becoming what is termed "ring shaken," the annual layers or circles at the centre separating from each other, which renders the wood of little value. Until, however, decay actually commences in the heart, the wood is of excellent quality, and for most purposes where durability is required equal to oak, particularly in young trees, owing to the early period at which it becomes matured as well as from the very small proportion of sap-wood which it contains. Marshall states that hop-poles of this wood last longer than any other; * and in palings, stakes, gate and other posts it has been known to last from twenty to thirty years, which is longer than most woods do in such situations.

Mr. Kent has observed a post of chestnut taken up sound after having stood above forty years.† And Miller says it will endure longer than elm to convey water underground.

Chestnut is useful for the same purposes as oak, but the wood of old trees should not be used in any situation where an uncertain load is to be sustained, as it is brittle; and as Evelyn states, often makes a fair show outwardly when it is decayed and rotten within. According to Belidor, it soon rots when built into walls, therefore the ends of joists formed of this wood should have a free space left round them.

The wood of the chestnut is nearly of the same colour as that of the oak. In old wood the sap-wood of chestnut is whiter and the heart-wood browner; but it is so much like oak in appearance that in old buildings they have been mistaken one for the other. Sir H. Davy says, " they may be easily known by this circumstance, that the pores in the alburnum of the oak are much larger and more thickly set, and are easily distinguished by the naked eye, whilst the pores in the chestnut require a magnifying glass to be seen distinctly. ‡

Chestnut has none of the larger medullary rays, which is a more decided difference, and renders it easy to be known from oak, whether the wood be old or not, particularly when cut in the plane of these laminae. It may also bo known from oak by its not becoming black when in contact with iron.

* 'Rural Economy of the Southern Counties,' vol. i., p. 216.

† 'Trans. Soc. of Arts.' vol. x , p. 30.

‡' Agricultural Chemistry.' p. 222, 4to edit.

The wood is hard and compact; when young it is tough and flexible, but when old it becomes brittle and shaky. It does not shrink or swell so much as other woods, and it is easier to work than British oak.

The cohesive force of a square inch of chestn * varies from 9570 to 12,000 lbs. when dry. The weight of a cubic foot of dry timber is from 43 to 54 8 lbs.

The properties as determined from a piece of young wood in a green state are as follows: -

The following are the results of experiments on two pieces of dry chestnut which had been cut from a tree of about thirty years old, and 11 inches in diameter, of rapid growth. The specific gravity was 0.535.

According to the experiment on the second specimen, the cohesion of a square inch of Spanish chestnut is 10,656 lbs., and the modulus of elasticity for a square inch according to the first experiment is 1,147,500 lbs.; according to the second, 1,126,656 lbs.

Chestnut bends more than oak at the time of fracture, and is therefore tougher; this permits it to yield insensibly until every particle exerts its utmost force, and then it gives way suddenly, more after the manner of metals than of wood.

The belief which has so long and so generally prevailed that the roofing and main timbers of many of our ancient buildings were framed of this timber, is a remarkable feature in the history of chestnut; but the examination and repeated experiments that have of late years been made upon it have satisfactorily proved that the timber which was mistaken for chestnut was oak, and chiefly of the sessili-flora species.

It is also curious that the same belief in the use of chestnut in ancient buildings had for a long time prevailed in France until disproved by Buffon and afterwards by d'Aubenton, who showed that the timber taken for chestnut was in fact that of the Quercus sessiliflora.