196 TREES AND TREE-PLANTING. 
of an impediment or faulty part the sound produced by 
a tap on one end of the log is not conveyed throughout 
its length to the other end, and so it becomes known if 
the wood be in a state of decay. 
The mahogany has become naturalized to the Eastern 
Hemisphere by its introduction into India,where it thrives 
luxuriantly, and in many parts grows abundantly. A 
species of this tree is found growing profusely in the 
forests of British and Independent Burmah, where it is 
known by the name of “ Pingado,” and is used as rail- 
road ties, and in bridging and buildings, as beams and 
piles. It is largely exported from that country, and is 
considered a strong, serviceable, and durable timber, and 
bears many characteristics in common with its fellow of 
the American continent. 
