OBSEEVATIONS ON CANADIAN CONIFER.E. 31 



5. The Kootanie and other similar coals probably had their oriirin in licjiiid hydro- 

 carbons, which penetrated the structure of jilants and then solidiiied ; the resulting rod-like 

 masses are the casts of such structures; the cementing matrix is the highly altered residue 

 of tlic original plant structure, while the present condition of the coal has resulted from the 

 action of water, followed by the pressure of superimposed sedimentary deposits. 



II. 



During the progress of a series of tests made by Prof II. T. Bovey a large number of 

 timbers of the Douglas fir (Pseadotsuga douglasu) were brought under examination. Several 

 of these were tim])ers which had been in use for some years in bridges and other railway 

 structures. During the progress of the tests these timbers exhibited certain peculiarities of 

 behaviour, under the influence of mechanical stress, which made it desirable to institute a 

 V)otanical examination for the purpose of ascertaining the cause of such behaviour and the 

 relations of strength to actual variations in structure. In order to gain a clear conception of 

 these relations it will be necessary to proceed with our examination somewhat in detail ; but 

 it may be stated at the outset that all the [leculiarities of fracture noted and all variations in 

 strength are such as may be explained by the structural features of a transverse section. I 

 shall, therefore, consider this direction of section only, at the present time, reserving it for 

 a future occasion to discuss those variations which are to be met with only in longitudinal 

 sections. 



Description of Specimens. 



Five specimens in all were submitted to me for examination, and will be described 

 under the numbers originally given them. These specimens were in the form of blocks 

 about eighteen inches long, and of the full transverse dimensions of the timbers from which 

 they were cut. 



No. Jf-2S was taken from the centre of a stringer from structure 428, half-way between 

 the Cisco cantilever bridge and Lytton. It had been in use about nine years. This timber 

 was probably grown on a flat three miles west of Hope, B. C, where most of the trees were 

 wind-shaken. 



This wood is of the "coarse-grained" variety, the red colour being a rather prominent 

 feature, and embraces zones 1, 2 and 3. The wood cuts hard and not very evenly ; the 

 dense summer wood is flinty, and under the action of a rather coarse saw is thrown out in 

 prominent ridges. Star and cup shakes are prominent, but in the former, whether developed 

 under mechanical stress or as a result of shrinkage, they are developed independently of the 

 medullar}' i-ays. 



Under mechanical stress the wood shears longitudinally, but the plane of fracture is 

 chiefly radial. 



No. 789. This specimen was taken from a stringer of structure 789 on the Kamloops 

 lake, six miles west of Savona, and had been in use eight years. The timber was probably 

 cut at the same place as No. 428, i. e., three miles west of Hope. 



This wood is of the "coarse-grained" variety, and embraces zones 1, 2, 3 and 4. It 

 cuts hard and not very evenlj'. The dense summer wood is flinty, and a rather coarse saw 

 leaves it in prominent ridges. Both star and cup shakes are well defined and commonly 

 connected by diagonal fractures. The star shakes are sometimes determined by the medul- 



