24 



HARDWOOD RECORD 



tree without pausing to read tlie writings of those who have studied 

 the subject, or to look to the experience of those familiar with the 

 lumber in its native land. 



The blue gum is indeed the most rapid grower of the genus in the 

 long run, though not the tallest, and forms an imposing tree, and 

 one which looks as though it would make splendid timber. Doubtless 

 this is one thing which has been in its favor. Another has been its 

 remarkable adaptability to a wide range of growth conditions, so that 

 it could be planted all over the state. It endures considerable frost 

 and drought. Then, also, it has been planted largely for purposes 

 irrespective of lumber, as tirewood, windbreaks, etc., for which pur- 

 poses it fully meets all anticipations. But it is a mistake to look 

 upon it primarily as a timber tree. 



In regard to saw timber, as that is primarily the subject with 

 which we have to deal, an examination of the lists of species which 

 we have derived seems to indicate red mahogany (Eucalyptus resi- 

 niflora) as the only all-round tree for this purpose. Further drying 

 experiments, which were made in the winter of 1912-1913 were in- 

 conclusive as to this species, for the reason that the oldest trees which 

 could be found in the state were only ten years old and not over 

 nine inches in diameter. The' wood of these immature trees, however, 

 three of which were obtained from Santa Monica, behaved, if any- 

 thing, better than blue gum and manna gum of the same age and 

 size; but it is impossible to predict how the mature timber would act. 

 The rate of growth of manna gum at the Santa Monica experiment 

 station is at best hardly two-thirds that of blue gum, although it is 

 reported to exceed the latter in the Hawaiian Islands. 



Sugar gum seems to be another promising species for regions free 

 from severe frost, and especially for dry valleys, but here again, its 

 growth is much slower than blue gum's, and it is a comparatively 

 small tree, and generally grows crooked. It is said that there is a 

 great difference in the value of the timber produced by this species, 

 according to soil and region of growth, being best on heavy, strong 

 soils, and poorest on sandy ones. The drying experiments of 1912- 

 1913, fully substantiate the claims concerning the wood of the sugar 

 gum. That from a twelve-inch tree grown at Santa Monica dried as 

 well as a piece of ash. The form of the tree, however, is inferior to 

 resinifera. The illustrations on page 21 show a grove of sugar gum 

 and one of resinifera, both of the same age — ten years old — growing 

 side by side at the Santa Monica experiment station. 



Tooart is another species which seems promising for warmer cli- 

 mates, free from frost, both moist and semi-arid. Neither the timber 

 nor the growth conditions seem to be very well known. A recommen- 

 dation of this species must be made somewhat reservedly. It was 

 impossible to obtain a tree of this species for the drying experiments, 

 as the only mature trees which could be found are three specimen trees 

 at Santa Monica, with which the authorities were unwilling to part. 



In connection with the blue gum, further mention should be made 

 of certain trees growing at San Jose which Mr. Gille.spie has been 

 cutting for a number of years and which have yielded excellent ma- 

 terial, quite different from the ordinary run of blue gum. Mr. 

 Gillespie claims that they are a distinct variety of blue gum, grown 

 from seed brought from Australia. Botanists have examined these 

 trees and have found no distinction botanically from the blue gum ; 

 yet it is not unreasonable to suppose that a difference in physical 

 properties might exist, even though no morphological distinction in 

 the leaves and fruit is discernible. We know this to be true of other 

 trees. Some are hardier than others, although no variety is dis- 

 tinguishable, and other differences sometimes occur. 



There woidd seem to be very good ground, therefore, for the con- 

 tention that the "San Jose gum," as Mr. Gillespie terms these trees, 

 might really be a distinct variety of blue gum. It is true that these 

 trees are now about forty-five years old, and are very large trees 

 growing along the roadside; but even allowing for this fact, there is, 

 nevertheless, a marked improvement in the wood over that of the 

 best blue gum trees grown under similar conditions. It shrinks less, 

 and more uniformly, and does not warp. 



Living trees contain internal stresses. This is especially true of 

 blue gum of diameters of two feet or less. The outer cylindrical 

 layers of the trunk are in tension, the inner core being in compression. 



This is by no means a merely nominal phenomenon, but is so marked 

 as to form a serious defect in the tree for lumber purposes, even if 

 the wood were suitable in all other respects. It would appear that 

 this distribution of stresses in the trunk of the tree is a natural 

 adaptation for the purpose of strengthening the long, slender trunk 

 against the bending action of the wind. Such would be the result of a 

 distribution of stresses in a wooden beam in this manner, since the 

 tensile strength of wood is about treble that of the compressive 

 strength. The great height of these trees, from 110 to 130 and even 

 170 feet, and their great weight make an enormous bending moment 

 at the base in heavy flinds. Large trees almost invariably show what 

 appear to be compression failures and consequent distortion of fibers 

 in the root swelling at the base. The tops of trees in a strong wind . 

 have been observed to bend over alj an angle of forty-five degrees. 



The effect of these stresses is evident in many ways. When the 

 tree is felled, it immediately checks on the end of the log, beginning 

 at the pith and running out radially. It usually splits in this manner 

 into quarters. These checks are in no wise due to drying or to the 

 process of filling, but entirely to the stresses referred to. As soon 

 as the trunk is cut across, the equiliberating forces are severed, and the 

 outer tension and inner compression open up the ends. These checks 

 extend inwardly but a few inches at first, but gradually extend fur- 

 ther as the adhesion of the fibers transversely gradually yields to the 

 tendency to bend outwards. 



These checks cannot be gotten rid of by sawing the end of the log 

 off, for as soon as this is done, new cheeks are produced at the cut 

 section. One of the most striking proofs of the existence of these 

 stresses is found in sawing a thin board or veneer directly through 

 the center of the log. This strip buckles up along its center and is 

 taut on the edges. 



Aside from tlie checking, these stresses produce another serious 

 result. When the green log is sawed into planks or timbers, the 

 stresses cause the pieces to spring out from the saw, and they will 

 always retain this curved shape unless straightened by force. Veneer 

 cut from any portion of the log will be dished all along the center 

 with taut edges. A board sawed diametrically through the center of 

 the log has been observed to open up at the two ends, and spring 

 clear in two along the heart as it leaves the saw. Wlion tlie timber 

 subsequently dries, these effects are accentuated. 



Trees three feet and over in diameter are nearly or entirely free 

 from these internal stresses, except for the region near the heart. 

 Consequently, one of the main diflSculties of using eucalyptus is 

 absent when very large tree.s are utilized. 



The first part of the jiroblem of utilteing blue gum for lumber is 

 evidently not a question of drying, but of obtaining wood while green 

 suitable for drying. Numerous experiments were therefore made in 

 an attempt to overcome the stresses in the green logs. Whole logs 

 were boiled and steamed in various ways and for different lengths of 

 time. Three days' steaming at two or three pounds gage, followed 

 by cooling under w^ater, eliminated the internal stresses, but so soft- 

 ened the fibers that the toughness of the wood was destroyed and the 

 wood checked in drying in a multitude of very fine checks. It was 

 fiually concluded that such attempts were futile from a practical 

 standpoint. 



Opportunity for Hardwood Flooring in England 



A recent consular report states that the use of hardwood flooring 

 in London is insignificant when compared with the use of soft- 

 woods. Hardwood is used to some extent in dance halls, skating 

 rinks and in private houses where much entertainment and danc- 

 ing is given, but even in such cases the tlooring takes the form of 

 parquetry rather than the hardwood flooring so widely used in 

 America. The hardwood for English flooring is derived chiefly 

 from the United States and Canada. 



It is believed that hardwood flooring will be used more gener- 

 ally in London partly because of its sanitary features and also 

 because of its beauty and the ease with which it can be cared for. 

 It woiild seem that big manufacturers of hardwood flooring in the 

 United States would find a very profitable market for this ma- 

 terial by pushing it in the big markets abroad. 



