File:Canadian forest industries July-December 1920 (1920) (20531847265).jpg

Title: Canadian forest industries July-December 1920
Identifier: canadianforjuldec1920donm (find matches)
Year: 1920 (1920s)
Authors:
Subjects: Lumbering; Forests and forestry; Forest products; Wood-pulp industry; Wood-using industries
Publisher: Don Mills, Ont. : Southam Business Publications
Contributing Library: Fisher - University of Toronto
Digitizing Sponsor: University of Toronto

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September 1, 1920 CANADA LUMBERMAN AND WOODWORKER 147 way trestles which have been in use for long periods, and in some of the shii)s on the Pacific Coast; one for example, the Lady Mine built entir(^!y of Douglas fir in 1879 at Port Ludlow and sti ll in ser- vice between Vancouver and Prince Rupert. The fact that Doug- las fir is recognized by the National Board of. Fire Underwriters as a proper tank material is an evidence of \-ts durability. Durine the war an immense amount of this material found its and aeroplane wing beams, come from near the outside of the log. This latter material is generally clear because of the fact that ordin- arily branches grow from the centre or pith of a tree out and, as the tree increases in height and the lower branches become shaded, they die of¥, the later wood forming over them being clear and of a high grade. As stated, the strength of a Douglas fir stick is closely related During the war an immense amount ot tms its density or dry weight per cubic foot. Of two sticks of equal way into boat and teroplane construction, ^^^.^, ""^^^^^ , '^^Vaero dryness oi degree of mc,istur J content the heavier will be the strong- uld be obtained ^^^'^J:^^^^'lJ!^tk^l ^. f^fi^ovided fh^ are of the same grade as regards defects knots, r^'T ""nH^ de^Hcks oHhe new Canadian Merchant shakes,, diagonal grain, etc. This density may be estimated by a M^\iL and should °^e the "ry be^ ^ervice and satisfaction. visual examination of the amount of the summer-wood in ^the annual That Douglas fir is popular in the East is shown by the increasing volume of this material which is finding its way in- to this market. It is especially useful as heavy construction material and is large- ly used in mill- building construc- tion, ' an outstanding feature of which is the recently complet- ed Hobberlin Build- ing on West Ade- laide Street, Toronto, designed by Yollcs & Rotenberg, archi- tects. This building, in the construction of which 1,000,000 board feet of Doug- las fir were used, is seven stories in height and contains 140,000 square feet of floor space, An interesting fact in connection with this type of construction is that the insurance rate on the building sprinklered is- lower than the rate for a reinforced building not sprinklered. and but very little higher than on a sprinkler- ed concrete building. Needless to say the timber is cheaper than concrete. There are t w o ways of cutting Douglas fir, one to give edge grained material which is best suited for floor- ing, decking, step- ping, etc., where hard wear has to be taken care of, and the other to give slash grained material which is prized as finish for the effect, in some nieces like watered silk, which ⢠^ is caused by the different colors of the "spring-wood" and 'summer- wood" which make up each annual ring or year's growth. It has been proved that the strength of wood vanes with its density of dry weight per unit of volume which in each tree varies with its position in the tree as to cross-section and height in the tree. A stick cut from near the centre of a tree is weaker than a stick cut from near the outside. Also, a piece cut from near the top of the tree is weaker than that cut from near the butt, therefore, the strongest timbers come from the outside of butt logs. Low grade structural timbers, such as railroad ties, often come from near the centre of the log and high grade structural material, such as car sills
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Stand showing the four chief coast species-Donglas Fir, Western Hemlock, Sitka Spruce, and West em Red Cedar or growth rings. Each year a tree adds an outside lay- er composed of wood formed early in the year called "spring- wood," and that formed later called "summer - woo d." The early wood is composed of compar- atively large oi)en thin walled fibres which function as conduits for the pas- sage of sap ; the later wood is composed of thick walled ele- ments which give the wood its strength. This wood is darker, more compact and harder, and appears as a dark yellow band. A tree having a large proportion o f this wood i s heavier and stronger than one having a n a r r o w band of summer-wood and a large percentage of the spring-wood. "Cross grain" may be due to two caus- es, diagonal grain or spiral grain. The former is caused by faulty sawing in that the saw cuts across the layers formed by the annual rings; the latter is due to no fault of manufacture, but to the fact that the wood fibres did not grow parallel with the main axis of the tree, but around it in a spiral. If the de- gree of diagonal or spiral grain is great, say more than one inch in twenty,, the material in which it occurs is materially weakened. The de- gree of diagonal grain, especially In -<()me sticks, is rather more difficult to detect. It is, however, readily shown on the slash or tangential face of a stick by the brovvn resin ducts, or in a dry stick by the season checks which follow the direction of the fibres. , \. â ⢠^ i The average oven-dry weight of Douglas fir is a^^proximately thirty pounds per cubic foot; green material approximately thirty- ei-ht pounds per cubic foot, and thoroughly air-dry material approxi- matelv thirty-three pounds per cubic foot. Douglas fir lumber weighs per M, b.m.. approximately 3300 lbs., green and 2500, V '-^ ^ ⢠^he color of Douglas fir varies from red to light yelU ^ red fir as a rule contains a high percentage of summer-

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