3922.] LOCAL WOODS. 117 



FOEBSTEY. 



LOCAL WOODS FOR USE AS MARINE PILES. 



By H. W. Moor, 

 Acting Conservator of Forests, Trinidad and Tobago. 



As some Interest has been taken lately in the kinds of local wood 

 suitable for marine use, and as a certain amount of information has 

 also recently become available regarding the suitability or otherwise 

 of some of these woods as marine piles, an attempt is here made to 

 collect and record what is known for the benefit of those interested, 

 and to serve as a foundation to which further information can be added 

 from time to time. 



Piles particularly are very subject to the attacks of the teredo and 

 limnoria, both allied to the mollusc family, and the chief desideratum 

 is immunity, in the greatest degree possible, from the ravages of these 

 destructive sea worms. Copper plating is not always possible, though 

 where there is a depth of mud or soft sand overlying the bottom it may 

 be tried with every hope of success. Creosotlng the wood has been 

 tried but is said to be a failure with wood used in tropical waters. 

 Eliminating outside aids therefore Immunity must be looked for in 

 properties essential to certain woods themselves. The large degree 

 of immunity enjoyed by the British Guiana Greenheart (Neciandra 

 Rodeii Schomb) is said to be due to the presence in the wood of an 

 alkaloid principle known as Bebeerine. Another wood has been 

 found of a genus represented locally by our Guatacre (Lecythis spp.) 

 containing silica crystals which are said to be present m sufficient 

 quantities to interfere with the worms' boring apparatus, making this 

 wood practically Immune. Hardness of the wood is another factor 

 in discouraging the attention of the teredo, though how much of such 

 immunity as is enjoyed by certain very hard woods is due entirely to 

 hardness, and how much to other properties (mostly chemical) 

 peculiar to such woods is a matter on which little is known at present. 



Other properties essential to woods used as piles are driving 

 ability and resistance to crushing strains and vibration and some 

 degree of freedom from warping, cracking and splitting, defects very 

 common in all tropical woods ; the suitability of any wood for this 

 purpose being as a general rule looked for in the length of the fibres, 

 the longer fibred hard woods being usually the more suitable. 



Taking all these factors into consideration, an attempt is made to 

 supply a list of local woods in order of merit which have been or may 

 be found suitable for piles, and (this with extreme diffidence) a column 



