50 THIt PltlNCIPAL rSRS OF WOOD. 



rapid traffic ; but the greater cheapness of metal tracks carrying 

 medium traffic and slow trains has been proved. 



8. Durability of the rails. — Wooden track superior. Experi- 

 ence in France tends to show that rails laid on wood last three 

 times as long as those laid on metal. 



9. Effect on the road-bed. — "Wooden sleepers injure it less. 



10. Effect on rolling stock. — Metal road perhaps less injurious. 

 On the German railways in 1883 the number of tire breakages 

 per 100 miles was 7"25 for a wood-laid way and 5"96 for a metal- 

 laid one. 



4. Palisading and fencing. 

 In this place we may leave out of account all fences of a merely 

 temporary character, such as those yearly put round fields and 

 enclosures in villages. The use of wood for palisades and fences 

 is necessarily limited in India by the nature of the climate and the 

 abundance of destructive insects, especially white ants ; moreover, 

 iron wire fencing is very much cheaper and practically imperish- 

 able. For standards for wire fences both round and squared 

 pieces are used ; for palisades, battens and planks are required of 

 woods that stand exposure well. 



5. Pit-wood. 

 This is required to support the roofs and often the sides of 

 the galleries and shafts. Wood so used remains in contact with 

 constantly moist soil in a constantly moist, warm and still atmos- 

 phere, and must, therefore, besides being strong enough to resist 

 all strains, be as durable as possible. The greater portion of the 

 wood used in mines consists of short pieces either round or squared. 

 At Warora Terniinalia tomentosa and Diospyros Melanoxylon are 

 the only woods that have been used up to the present ; but several 

 other kinds are now under trial. 



Article 3. Timber used in contact with water. 

 Under this head are comprised piles used in rivers and in the 

 sea, sluice gates and other permanent canal works, water-wheels, 

 wet slides, fascines for protecting river banks, &c. Wood in con- 

 stant contact with water, especially if it is alternately exposed and 

 covered, or is in shallow water full of air, is placed in the worst 

 possible conditions for its preservation. On this account none 

 but the most durable kinds should be so employed. For fascines 

 for protective works rapid-grown coppice shoots are the best. 



Article 4. Timber used isr or with machinery. 

 The most common Indian instances of wood used in machinery 



