File:Canadian forest industries 1908 (1908) (19902866993).jpg

Title: Canadian forest industries 1908
Identifier: canadianforest1908donm (find matches)
Year: 1908 (1900s)
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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Text Appearing Before Image:
CANADA LUMBERMAN AND WOODWORKER 25 is absolutely correct, though near enough as far as the cuts are concerned, the greater deviation being in the hip for the square cornered building. It lacks .0295 of being 17 inches and represents the run of the hip to a 12 inch run of the common rafters. Its true length being 16.97505 inches, this is the length from which we have reckoned for the lengths of the hips instead of 17, as is the usual custom. This may seem a trif- ling difference, and so it is in a short run and low pitches; but suppose it is for iron construction. To begin with, the shortage of each foot in run with the common rafter is .0295 of an inch; added to this the gain well to know this discrepancy and guard against it when the occasion demands, and for that reason we give the correct amounts. The short- age in the octagon is not so pronounced. Instead of it being in the run, it is the tangent that is lacking the same amount, it being 4.9705 instead of 5 inches. This, coming as it does, cannot affect the length of the raf- ter nearly so much as in the above. We explain this shortage better by referring to that part of the illustration which shows the plan of a combination square and octagon frame with the heel of the steel square resting at the centre. From this
Text Appearing After Image:
o > X * O 9: Or 29.36 28.55 27.76 26.96 26.21 25.45 24.72 24.00 23.31 22.64 21.99 21.37 20.78 20.22 19.69 19.21 18.76 18.36 18.00 17.69, 17.43 17.23 17.09 17.00 16.97 it would have in the pitch, which would be .015 of an inch by the time .0295 to start with would be a difference of- .0445 of an inch to the foot in run with the common rafter. Now suppose the run to be 18 feet; 18 times .0445 equals 8 plus, or 19-24 of an inch difference; or, if no account was made of the gain in pitch, the .0295 of an inch in the run would amount to over half an inch in the length of the hip alone. This is a common error, and while it is not much, and probably would never be noticed in wood construction, it is it will be seen that the two outer circles catch the corners of the frame and seemingly intersecting the tongue at 13 and 17 and represent the figures to use on that member for the seat cuts, but the true length of the run of the hip is 16.9705, and that for the tangent of the octagon is 4.9705. In connection with this illustration we also give a table of decimal equivalents to the one-twenty-fourth part of an inch for convenience in finding their value in common fractions.

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