Very little wood is now used as engine or machinery parts. Metal has displaced wood almost entirely in moving and stationary parts of machines, and in many general uses for which wood was once exclusively employed. The present highly developed industry of pressing sheet metal to many forms more or less intricate has made it possible to substitute metal for wood in furniture, house and ship trimmings, automobile body fittings, utensils and many other articles.

However, wood remains a very useful structural material, and is particularly of value in engineering needs as a material for making patterns of objects to be cast in metal, as will be seen in Chapter VIII (The Pattern Shop. 220. Work Of The Pattern Shop).

Wood is used for decks and sheathing of ships, and for many parts in ship equipment. About the only important use remaining for it in marine machinery is as bearings for propeller shafting. These bearings support that part of the shafting between the propeller and the body of the ship. They cannot be given care or attention except when the vessel is in dry dock, and are lubricated entirely by the water in which the vessel floats. Lignum vitae, a tropical wood, is used for this purpose.