Of the 72 manufacturers replying to the questionnaire, 7 reported no lumberyards at the sawmill, having replaced air-drying with kiln-drying on such of their product as was not sold in unseasoned form. These included 1 mill in North Carolina pine, 4 in southern pine, and 2 in Douglas fir. Of those having yards, 49 mills reported a total yard acreage of 2,05712 acres, and 54 mills reported a total yard piling capacity of 1,225,500,000 feet. The yard topography was high, level, sloping, or rolling as reported by 34 mills; 27 reported a level or low-level site, and 1 stated that the yard was partly on high and partly on low ground. Natural drainage was described as good for 53 yards, poor or only fair for 10, and had been improved by ditching or filling in 34 yards. The foundation soil was sand or gravel for 19 yards and as combination of gravel or sand with loam for 10 others; for 13 it was clay or a mixture of clay with loam or sand; loam was the soil in 9 yards, while gumbo, decomposed lava, heavy red soil, and rocky soil were each reported for but a single yard. Gravel, sawdust, and hogged mill refuse had each been used for top filling in two yards; rock and sand, and the wood ashes already mentioned, in one each.

In 27 yards the main alleys ran north and south, so that the ends of piles got either the morning or the afternoon sun; in 20 yards the direction was east and west, in 7 both ways, and in 2 in an oblique direction. The prevailing wind was sidewise to the lumber piles in 28 yards, endwise in 12, both ways in 11, and oblique in 6; and most of the replies agreed that little difference of effect on the lumber could be observed.

Some sawmills are provided with a separate transportation system for outgoing lumber, consisting of railroad tracks laid through the yard between the rear ends of the lumber piles; and unpiling is loaded directly into cars on these rear tracks, from the rear end of the piles, while piling is done from the front alleys as usual.

The alley leading from the mill into the yard is usually one of the main alleys, but it may be a cross alley with the main alleys branching from it on either side. It is usually considered best to run the main alleys north and south, so that the pile will get the morning sun on one end of the lumber and the afternoon sun on the other.

Sometimes the direction of prevailing wind is of more importance than the direction of the sun, with relation to the piles. Where the prevailing wind is northerly or southerly the above arrangement will be the best possible, because it will leave the piles sidewise to the wind, which is the direction in which air can best circulate through the piles-in the direction of the sticker lines instead of across them. If, however, the wind is westerly or easterly while the main alleys run north or south as above suggested, considerable advantage will be obtained by spacing the piles evenly along the alleys so that the spacing between the piles constitutes straight unbroken openings for the wind clear across the yard. The chances in such case are that the breeze will have sufficient quartering to establish considerable circulation sidewise through the piles. Air movement through the piles is an important factor in air drying. Air in contact with the lumber inside the piles tends to become cooler and heavier as it absorbs moisture from the lumber, and sinks, drawing in fresh air; but this movement is slow, and the tendency is for

this air to pile up and remain near the ground, in the absence of a breeze to sweep it away. A film of dead air may remain close to the surfaces of the lumber, slowing up evaporation unless it is swept away by a brisker current of air.

Formerly elevated trams were constructed through the mill yard as highways for lumber movement. These favored higher piling of piles but interfered with air circulation to such an extent that lumber in the piles below the tram level dried more slowly, to a very noticeable degree, sometimes accompanied by additional stain or mildew. Elevated trams are not now universally used; in some cases plank roads are laid through the alleys, directly on the soil. Such planks develop decay, limiting the life of the roadway and also constituting a serious source of infection for the lumber in pile. Wherever the fruiting bodies or "toadstools" of fungus develop, they send out literally millions of spores to float in the air and infect whatever wood, in favorable condition for infection, they may light

It is important to keep such sources of infection out of the lumberyard. A plank road elevated on a suitable framework a foot or more off the ground, and using treated or creosoted wood for contact with the soil, would be more expensive but would last longer and would not be high enough to interfere with seasoning in the bottoms of lumber piles.

A study of the questionnaire replies received shows that elevated trams are used in the yards at 20 mills and at 4 other mills are used in part of the yard, while the other portion is served with grade railroads, or cement or graveled roads. Grade railroads serve the yards at 11 other mills, and 11 have either plank roads or grade trams; 8 have dirt or graveled roads; the roads in 1 are made of hogged mill refuse and in another are paved. An interesting development of yard transportation is at a plant in Lumberton, Miss., where the yard is laid out with railroad tracks in the main alleys built on an incline so that cars will move by gravity from one end of each alley, where the green lumber is received, to the other end, where the dry lumber is sent out.

At 22.2 per cent of the plants reporting the main alleys in the yard were spaced 30 to 39 feet apart; at 33.3 per cent, 40 to 49 feet; at 20 per cent, 50 to 59 feet; at 17.7 per cent, 60 to 69 feet; and at 6.6 per cent, at 70 feet or over. At 4.16 per cent of the mills the main alleys were under 10 feet wide; at 54.16 per cent, 10 to 19 feet wide; at 33.3 per cent, 20 to 29 feet wide; at 4.16 per cent, 30 to 39 feet wide; and at 4.16 per cent, 50 feet wide.

A study of replies as to yard acreage and capacity, in millions of feet, showed a wide range in relationship between the two. The average footage per acre for the entire yard ranged from a quarter of a million feet up to a million feet. If the entire space is covered with piles 16 feet square on main alleys 16 feet wide and with side space of 4 feet, and space between piles at the rear of 8 feet, and with space between boards in the pile equivalent to half the width of boards, it would require about 75 courses of inch lumber pile to total a million feet per acre, which (if inch stickers were used) would make a pile about 122 feet high. This computation includes no allowance for cross alleys or of idle space; where mill yards use higher piles and closer spacing it naturally reduces the effect of wind and

sun on the piles and makes for somewhat slower drying. The tendency toward open piling is most pronounced in the reports on species which dry more slowly, while crowding is more noticeable in the species that are easier to air season.

The difference in yard sites and layouts often accounts for differences of seasoning efficiency. Damage occurs to the lumber from dry too rapidly or too slowly, and the location of the yard may be the determining influence. In one southern hardwood mill yard it was found that change in position of piles with reference to prevailing breezes was sufficient to do away with most of the previous trouble over staining of lumber in pile.

PILE FOUNDATIONS

The general tendency is for lumber in pile to season most rapidly in the top of the pile, more slowly in the middle, and most slowly in the bottom third of the pile; more slowly of course in the interior than in the sides of the pile. Seasoning in the bottom of the pile may be helped somewhat by more open piling in that portion-using thicker stickers or occasional thicker courses, also wider spacing between boards, and interior chimneys or tunnels. One of the most important factors in promoting seasoning in the bottom of the pile is the provision of air circulation beneath the piles, by giving the pile foundations adequate height, and so arranging them that they do not interfere with the free sweep of air.

What is known as a continuous foundation consists of two or three continuous lines of walls formed of timber supported on the ground, running lengthwise of the alley and spaced apart a sufficient distance to form cross supports for lumber piled endwise to the alley. These solid timbers cut off air circulation under the piles except in the direction of their length; and spacing suitable for a given length of lumber will not be suitable for longer or shorter stock. Sometimes such foundations are built up crib fashion of short timbers, affording some air spaces through the walls but not usually in adequate degree. Another foundation consists of timbers laid on the ground but running lengthwise instead of crosswise of the pile. There should be three of these for each pile, with crossers suitably spaced for the length of pile; but the heavy longitudinal timbers again offer an impediment to the circulation of air beneath the piles crosswise of the Jumber.

A foundation begins to approach proper form when the heavy timbers are well elevated above the ground on posts or concrete piers, so that they are not so liable to decay and the circulation of air will be better beneath the piles. If posts are used, they are generally set on mudsills, which, being the only members in contact with the ground, are most liable to decay. The superstructure may be of uncommercial material perhaps already infected with fungus, which may develop and become an active source of infection to lumber in pile. Figures 2, 3, and 4 show various types of foundations at sawmill yards. Development of decay should be avoided, if possible, in foundation timbers, but such material is more dangerous as source of infection for blue-stain fungus than decay fungus, whenever bluestain trouble is present, for blue stain develops more rapidly and is

more apt to do visible damage to the lumber in pile. It has ample opportunity to develop the inconspicuous fruiting bodies and their crop of spores, while stain developing on lumber in seasoning is soon confined to the interior by drying of the surface, and thus is largely

FIGURE 2.-Concrete pier foundations under construction in a southern mill yard. The stringers shown support heavy crossers not yet placed, which may be shifted for desired lumber length and spacing. Photograph courtesy of Forest Products Laboratory

FIGURE 3.-An old foundation at the right, of a type now being replaced by the improved foundation at the left, giving more ventilation under the piles. Photograph courtesy of Forest Products Laboratory

prevented from forming fruiting bodies, which of course must occur on the outside of the piece. This applies generally also to trash of all sorts in the yard; decay-fungous fruiting bodies developing on it are readily visible and carry their own warning, but the stain fungus

can develop a cloud of spores without giving visible evidence to ordinary observation. All trash must be kept out of a lumberyard.

Weeds also should be excluded as far as possible. The best method is to provide a surface in which weeds will not grow; failing this, their prompt removal as often as necessary is the usual available recourse. Where they grow luxuriantly, use of weed-killing chemicals might be desirable. In a western mill yard about a hundred sheep were turned in and quickly cleaned up the vegetation, but not all manufacturers will be able to use this hint. A ground cover of weeds interferes with ground movement of air and therefore with circulation around pile bottoms; and the weeds themselves

FIGURE 4.-Two sawmill yard views showing concrete piers. In the one at the left the piers support stringers on which the crossers are placed; at the right the heavy crossers are placed directly on the piers, a less flexible arrangement. Photographs courtesy of Forest Products Laboratory

draw up a good deal of moisture through their roots and evaporate it through their leaves, thus adding to air moisture. Figure 5 shows piles too low and growth of weeds.

A considerable number of the questionnaire replies included rough sketches of foundations used, giving a fair idea of the range of practice. It appears that 71.7 per cent of the foundations reported have the main timber crosswise and serving as foundation crossers for the pile, and with wooden supports of some sort underneath; 5.6 per cent were of similar construction but had the crossers supported on concrete piers. In 22.7 per cent of the foundations the main timbers were longitudinal, and heavy cross timbers were used on top of these to support the lumber. This type was used for the California pines and for southern hardwoods more particularly, and less frequently for cypress, southern pine, and western pine.