94 TREES — TIMBER. 



eludes that the growth of our common European trees havinor gone 

 on with a certain rapidity to the age of from about fifty to seventy 

 years, then became slower, but continued regular to extreme age. 

 The inequalities of growth, con^ipicnous in the different thicknesses 

 of different rings, he thinks are mainly due to the kind of soil which 

 the mass of the roots encountered in their progress, or to the re- 

 moval of other trees which grew in the \icinity. The diminished 

 thickness of the rings, after trees have passed a certain age, he 

 ascribes to the depth to which the roots have now penetrated, and 

 their consequent remoteness from the air ; and further, to the resist- 

 ance opposed to the expansion of the trunk by the bark, which has 

 now become thick, hard, and unyielding. Mr. Knight found that 

 old pear-trees, relieved of their outer bark, formed more wood in a 

 couple of summers afterwards, than they had made in the twenty 

 years that preceded the operation.* 



The forests of intertropical countries produce a vast number of 

 gigantic trees, many of which might doubtless be turned to excellent 

 use ; but the information we have on the trees of these latitudes is 

 very imperfect. In New Granada, the wood which is known undei 

 the name of wood of St. Martha, (aslroneum gravcolens ?) is fre 

 quently employed for building purposes as well as for making furni- 

 ture. It is very hard, and more beautiful than mahogany, its color 

 being deeper. M. Goudot measured a tree of tliis kind, which was 

 1.6 metre or nearly 4\ feet in diameter, including the alburnum, and 

 had 32 centimetres or upwards of 18 inches of heart-wood. Belfries 

 having supports of this wood are met with, which have stood for 

 more than a century exposed to all the inclemencies of tlie weather. 

 This tree grows in the dry soils of the hottest regions of South 

 America, and seldom at an elevation of more than aljout fifteen hun- 

 dred feet above the level of the sea. 



Cedar {cedrcla odorata) is never attacked by insects, doubtless 

 because of its aromatic odor ; this valuable property makes it in- 

 valuable as building timber. The tree attains to large dimensions. 

 M. Goudot measured one in the forest of Quindiu in South America, 

 which was upwards of 150 feet in height by more than 6j feet in 

 diameter. It grows freely throurrh a zone of considerable breadth, 

 from a height of about 3280 to 65G0 feet above the level of the sea, 

 a circumstance which, according to my own oi)servations, would in- 

 dicate the extreme temperature of the district which it inhabits to 

 be between 66" and 76" Fahr. 



There are several other beautiful and useful timber trees of the 

 Cordilleras — the Nogal {juglans . . .1) which grows between C500 

 and 9800 leet above the sea line ; the escoho, {.Uepino {taxus montana 

 Willd.) whose region lies between the 2.800 and 11.400 feet of ele- 

 vation ; the arai/an and the guayacariy — all are serviceable in one 

 direction or another. The caracoli {anacardium caracoli) and the 

 fig (Igncrones) are trees which attain to extraordinary sizes, and 

 afford light woods that prove uset'ul in rarious circumstances. Uc 



* De Candolle, Vegetable Physiology, p. 975. 



