TIMBEK USED ON, OR IN, THE GROUND. 117 



used, as it is essential that the piles should be straight. Spruce 

 wood is often used in the absence of better material. 



2. JVoodoL Watcr-inpes. 



Although iron water-pipes are everywhere replacing wooden 

 pipes for aqueducts, yet in certain well-wooded countries the latter 

 are still used, and for this purpose the best Scotch pinewood, 

 larchwood, and black pinewood are most suitable. 



These woods usually last 8 — 10 years, if they are laid at a 

 proper depth below the surface of the soil, somewhat over 2 feet, 

 where frost and heat do not affect them. 



Failing these, woods of spruce, silver-fir, and alder may be 

 iised. Oakwood gives the water a bad taste, and is too expensive 

 for the purpose, and other woods are not sufficiently durable. 

 [Deodar-wood is the best to use in the Himalayas for aqueducts. 

 — Tk.] The wood is bored and used quite green, and supplies 

 of wooden pipes must be kept in running water to prevent 

 warping and cracking. It is preferable to keep them in dry 

 sheds than in stagnant water, where spores of fungi get into the 

 tubes and cause premature decay. 



Single pipes are 9 — 16 feet long, as it is difficult to bore 

 them to a greater length. The wall is generally as thick as the 

 bore. 



3. Wood used for Timher Export-Works. 



Wood is also frequently used in forest export-roads, slides, or 

 sledge-roads. Wherever there are extensive coniferous forests, 

 and the local prices of wood are low, large quantities of wood 

 are used for fencing, supporting embankments, culverts, bridges, 

 and for covering swampy ground ; all kinds of wood, chiefly 

 coniferous wood, are used. 



4. Wooden Paving. 



Wooden paving is now employed in the streets of large cities. 

 [In London, jarrah {Eucalyptus marrjinata) and kari {E. diver- 

 sicolor) are now largely used for this purpose, and doubtless 

 Pyngado {Xi/Ua dolahriformis) , and other heavy Indian woods 

 might be used with advantage. — Te.] Among European species 



