Growth and Conversion of Timber.

Progress, Volume II, Issue 2, 1 December 1906, Page 45

Growth and Conversion of Timber.

The natural growth of a tree not only indicates the nature of its wood as timber, but also its uses in various capacities in building and other work. It is not out of place to review the growth of the tree and its conversion, and use for various purposes, the mobt simple of which is the natural wood as

used in rustic work. The terms in timber, however, would form a very respectable scientific dictionary. There are for instance: —

STRING AND CALIPER MEASURES. The difference implied m the terms string and cahper measure, expressing two different modes of measurement, will be more easily understood when it is explained that the " caliper " is the measure used in determining the freight due to a ship for space occupied in her, and " string " is the measure by which the artisan or joiner is charged for the actual amount of convertible wood in the log or piece sold to him. A waney log, of course, occupies as much space in the hold of a ship as a perfectly square one, and therefore caliper, or extreme, is the just measure for determining the freight ; but to buy by that measure is to pay for wood which is not obtained. It is contended that when timber is sold by caliper measure the difference between it and string is made up in the price chaiged ; but that is a question which must be left to others to discuss. The difference between string and caliper measure is asserted to be about thirteen per cent. ; but much depends upon the liberality of the broker in the case of string measure, and the keenness of the measurer, in the other case, in applying his calipers to the widest parts of the log.

" FAULTS " IN TIMBER. " Burrs " or excrescences on trees, owe their existence to the crowding together of small germs, apparently the unsuccessful attempts at the formation of branches from one individual spot, whence it is supposed arise those bosses, or wens, which almost appear as the result of disease, and exhibit internally crowds of knots, with fibres surrounding them in the most fantastic shapes. Sometimes the burrs occur of immense size, so as to yield a large and thick slab of ornamental wood of most confused and irregular growth, and consequently the more valuable for veneers. " Foxey " wood is disfigured by dull red stains which indicate growth in a marshy soil, and are the signs of approaching decay. These stains are generally round the heart of the tree. Timber grown on loose soil is often what is termed " quaggy " — that is, the centre of a tree is full of shakes and clefts. Sometimes a shake will extend round a great portion of the trunk between two of the annual concentric layers, so as to divide them from each other. This is called a " cup shake," and the timber is said to be " cuppy.'" It is not attributable to the soil but is supposed to originate in the effect of frosts on the aqueous sap in its ascent. When the alburnum of a tree has been wounded, or a branch improperly lopped or damaged the subsequent growth of a tree will cover it, and it is then called a " rind gall," which, should the injured part have time to become decayed or partially so, or even sodded with the rains, will frequently cause excessive rottenness in the tree. " Doatmess," probably " dottmess," which is of a spotted or speckled appearance like small stains in the wood, is a disease generally incidental to the soil. " Spine " is the name given to the mature wood of a tree, the outer layer being called alburnum, or sapwood.

TWIST IN TIMBER. The " twist " of the wood of many trees is a phenomenon well known to wood cutters, carpenters and others. Most trees show the obliquity of the woody fibre more or less. In certain species the twist is almost uniformly in the same direction, and in others both directions occur with equal frequency; while in not a few, no twist is distinctly discernible. Sometimes the same directions prevail in the majority of a species of a genus, or even of a whole family. In some instances nearly allied species of Europe and America twist in opposite directions. In a few instances the fibre of a young tree is twisted in one direction, and that of the old tree in the opposite direction, the observer being supposed to imagine himself in the centre of a coil, in order to ascertain whether the direction is to the right or left. The cause of the twisting is connected with the growth of the wood cells, of which the ends at their formation are horizontal, or nearly so, but which become wedge shaped as they elongate : but this is not sufficient to explain the higher grades of the obliquity, which sometimes reaches an angle of forty-five degrees. — Carpenter &• Builder.