290 



AMERICAN FORESTRY 



applies more particularly to the forests along the 

 Demerara and Essequibo Rivers in British Guiana, though 

 it obtains also in part to the regions in Dutch Guiana, 

 where the rivers are not so long and present less formid- 

 able rocky impediments. The transporting facilities which 

 the ri\'ers in a countrv without railroads afford is verv 



HAULING GREENHEART LOGS 



ILarge quantities of this wood have been regularly exported to Europe 

 for over a hundred years. It is popular tor permanent marine struc- 

 ture. 



great, even from the extreme 

 sources. The small tributaries 

 are made passable by removing 

 all the dead logs ( locally called 

 tacubas ) ■ which have accumu- 

 lated for hundreds of years. In 

 some instances it costs almost 

 as much per mile to clean and 

 straighten a creek in the interior 

 as it would cost to grade for 

 laying the ties and rails of a 

 railroad. All the streams are 

 meandering and in a good many 

 places new channels have to be 

 excavated in order to facilitate 

 the carrying of logs. This fre- 

 quently necessitates the removal 

 of massive trees and old stumps 

 before logs can be carried down 

 stream, which is often done in 

 less than 3 feet of water by 

 chaining one or two logs on each 

 side of a fiat-bottom boat locally 

 known as ballahoo. 



Greenheart wood varies from a greenish-yellow color 

 to dark or nearly black. The heartwood is always 

 darker than the sapwood, though the latter becomes 

 deeper in color upon exposure, and it is often difficult 

 for the inexperienced man to distinguish the sapwood 

 from the heartwood in the sawn condition. The color 

 of the wood is due to the presence of a greenish color 

 substance known as greenheartin. It is believed that its 



extraordinary freedom from decay is due, at least in 

 part, to the tyloses in the pores of the wood and prob- 

 ablv also to the presence of the alkaloid biberine. Green- 

 heart has no decided characteristic odor, even in the fresh 

 state. This is contrary to expectation, because a great 

 majority of the trees related to it have wood with very 

 pronounced pungent or spicy taste and odor. The wood 

 is very hard, heavy (about U) pounds per cubic foot), 

 very strong, though brittle, and exceedingly durable. It 

 is probably the most durable wood known, and is espec- 

 ially valuable, therefore, in a climate like that of tropical 

 America, where the elements favoring decay are so 

 nnmsrous and powerful. Greenheart in the unseasoned 

 s:ate is moderately easy to work, but after it is thoroughly 

 dry it becomes so hard that sawing or nailing becomes 

 difficult. It seasons rapidly and shrinks very little, and, 

 being free from tannic acid, it does not injure iron to 

 any appreciable extent. 



Greenheart is said to be one of the strongest timbers 

 in use, with a crushing strength of 12,000 pounds per 

 square inch. (l'> per cent greater than that of English oak. 

 The shearing strength parallel to the grain is between 

 l.SOO and 2,000 pounds per square inch. From all the 

 records of tests made on greenheart it appears that it is 

 superior to oak in all its properties, except perhaps in 

 toughness. While the results of the mechanical tests 

 made on greenheart vary considerably, the variation is 



SNAKING CREl'.Mll-AUr LOGS liV i.AXGS OF MEN 



not so great as in the case of our white oak, whose 

 properties vary exceedingly according to the locality. 

 Users of greenheart ha\e frequently noticed that logs 

 a])parently sound lacked in strength and toughness, and 

 that the darkest colored wood is the most durable. It 

 does not vary so much in density and all of it is very 

 fine-grained and takes a very fine polish. The bulk of the 

 wood that comes to the market is straight-grained. Some 

 of the uUl trees are curly-grained, locally known as "bull- 



