121. Lumbering.—Lumbering is of two kinds: conservative and ordinary. The first seeks to so treat the forest that successive crops may be produced; the second takes no account of the future—it cuts only the better parts of the trees, often destroying young and promising trees in so doing.
Lumbering in the United States is usually carried on at quite a distance from habitation. A camp is, therefore, prepared at a spot convenient for the logging operators, Here the men eat and sleep.
A lumberman selects the trees which are to be cut and marks them with a hatchet to prevent mistakes.
These trees are felled either with the .ax or saw, some times both. Fig. 205. When the trees are down, the lower branches and top are trimmed off with axes, after which the trunks are sawed into logs of convenient length.
These logs arc dragged away and collected in piles. This is called skidding, Fig. 206. Skidding is usually done with horses or oxen. From these piles the logs are loaded upon sleds, Fig. 207, and hauled to the place from which they are loaded on cars, rolled into a stream or otherwise transferred to the sawmill. Fig. 208 illustrates a method used in the south.
Logs are transported to the sawmill in various ways: They may be loaded on cars and hauled to the millpond, Figs. 209 and 210. They may be floated down some stream.
Where a stream is not deep they arc often collected in the bed just below a specially prepared dam called a splash-dam. When the dam is opened the sudden flood carries them along. Logs are often made into rafts where the stream is large and deep or they may be floated singly. Men called log or river drivers accompany these logs. It is their duty to break up any jams which the logs may form. River-driving is dangerous work and requires great daring on the part of the men. They must learn to balance themselves on floating, rolling logs.
Pig. 209. loaded train of lonci.eaf pine, barham, uisiana.
When a log jam is broken the logs go out with a great rush and the driver must make his escape as best he can.
122. Milling.—If the sawmill is located upon the banks of a running stream the logs are enclosed by a log boom until they are wanted for sawing. Fig. 211. Log booms are made by chaining logs together and stretching them across the river; they are to the enclosed logs what fences are £o cattle.
Soaking logs in water helps to clean the wood. The mineral matter which is soluble is washed out.
Three kinds of saws are in common use in cutting logs into lumber: circular, band and gang. Circular saws cut faster than band-saws but are rather wasteful because they cut such a wide kerf. A large circular saw frequently cuts a kerf one-quarter of an inch wide. Gang saws cut out several boards at the same time. Band-saws, because of their economy, are displacing the others.
Pig. 210.unloading logs from train, pinogrande, california.
The common forms into which logs are sawed are timbers, planks and boards. Timbers refer to the larger pieces such as are used for framing; planks are wide pieces over one and one-half inches thick; and boards are wide pieces one and one-half inches thick or less.
At the mill the log is drawn from the water, up a slide, Fig. 213, by an endless chain. In the mill it is inspected for stones and spikes and then measured. Next it is automatically pushed out of the slip upon a sloping platform called the log deck where it is held by a stop until it is wanted at the saw.
Fig. 211. the glens falls boom, hudson rtver, new york.
Fig. 212. log pond near ocilla, georgia.
double cut saw mill, pinogrande, california.
When the carriage is empty the stop is withdrawn and at the same time revolves so as to throw the log upon the carriage. Iron hooks called dogs arc then fastened in the log in such a way that it cannot turn. Fig. 214.
The carriage and log move toward the saw and a slab is cut off the log. A reversing lever takes the carriage back; again the log is moved to the saw. This is repeated until a few boards are cut off. The more modern band saws have teeth on each edge of the blade so that the log is cut as the carriage moves backward as well as when it moves forward.
Fig. 213. log slide at a mill in southern georgia.
The dogs are released and the log is given a half turn on the carriage by means of a steam "canter." The side from which the slab and boards were sawed is placed against the knees—the standards or uprights of the carriage—and the log again dogged. The opposite slab and a few more boards are sawed off after which the log is given a quarter turn and all but a few boards taken off.
A half turn of the log and the final sawings are made.
A series of "live" rolls—rolls which revolve in one direction—carry off the boards. The rough edged boards, which constitute about one-third of the whole number, are held by stops and finished on saws called edgers.
The boards are now passed on to a trimmer or jump saw and cut to standard lengths. Timbers are trimmed to length by a butting saw. Slabs are sawed to a length of four feet one inch on a slasher. These slabs are sawed into laths, pickets, or blocks the length of a shingle, called shingle bolts. From these bolts shingles are sawed.
123.Quarter Sawing.—Fig. 215 shows a common way of sawing '' quarter-sawed'' lumber.
The faces of most of the boards are cut nearly parallel to the medullary rays, these rays come to the surface at small angles and make the beautiful spotting often seen in oak and sycamore. Quarter-sawed boards do not warp or twist as much as the plain sawed because the annual rings are perpendicular to the face.
124.Waste.—Attached to every sawmill will be found tower like structures from the tops of which smoke issues, Fig. 216. These are called burners and into them are thrown thousands of tons of waste wood. Waste wood is used as fuel for the engines and for many other purposes, but there still remains much that is burned as the cheapest way to get rid of it.
Fig. 216. a modern sawmill, showing refuse burner.
125.Lumber Transportation.—Sawed lumber is transported to the yards in various ways. It is loaded and carried by boats, by cars, and in some places is floated to its destination in narrow wooden troughs called flumes.
On the Pacific coast mills arc frequently built out over the water on piles so that the lumber is loaded directly from the saws. Frequently lumber is formed into rafts and towed to its destination in a manner similar to that of the log rafts of the Pacific.
126. Seasoning.—There are two methods of drying wood in common use—air drying and kiln-drying.
When lumber reaches its destination it is sorted and graded according to lumbermen's standards, after which it is loaded upon trucks and hauled to the storage yards. Here, it is so placed that air can get at the four sides' of each piece and evaporate the water held by the "green " lumber. This is called air seasoning. The time necessary to season a piece of lumber so that it may be used for high-grade work depends upon the kind of wood, its shape and size, the condition of the atmosphere, etc.
Two, three, and even four years are often required; the longer the better, provided it is kept dry.
It will never become perfectly dry because of the moisture in the air itself. Because of the slowness of this method of seasoning, millmen resort to artificial means. The lumber, as it is needed, is shut up in a room heated by steam. Fig. 217 shows the method of "sticking" lumber in preparing it for the kiln.
High temperature, no matter how much moisture may be contained in the air, will evaporate water from wood. Green, or fresh sapwood may be partially seasoned by boiling it in hot water or by steaming it.
Pine, spruce, cypress, cedar, etc., may be placed in the kiln as soon as sawed, four days for one inch thick boards being sufficient to dry them. Hard woods, such as oak, maple, birch, etc., are usually allowed to "air season" for a period of from three to six months before being placed in the kiln. Six to ten days additional kiln-drying is allowed them.
The usual temperature for kilns is from 158 to 180 degrees Eahr. Hardwoods lose moisture so slowly that to place them in the kiln directly from the saw would cause them to shrink very unevenly and hence make them subject to serious "checks."
Lumber is frequently steamed to prevent its checking and "case hardening" while being kiln-dried.
127. Lumber Terms and Measurements.—"Clear" lumber is lumber which is free from knots and sapwood.
"Dressed" lumber or "surfaced" or "sized" lumber is lumber which has passed thru the planer.
The unit of measure is the board-foot which is one inch thick and twelve inches square or its equivalent. Boards less than one inch thick are sold by the square foot, face measure.
Shingles and lath are sold by the 1,000, the former being packed in bunches of 250 each and the latter in bundles of 50 each. Moldings are sold by "running" or lineal measure.
Prices are usually based upon the thousand feet; thus, 200 feet, 1st, clear, S2S, (sized or surfaced on two sides) at $47 per M.