236 ON THE WOODS AND PLANTATIONS 



have in parts been allowed at one time to grow pretty thick, and 

 there they are generally long and small. But wherever they 

 have had room to expand they seldom grow to more than 30 feet ; 

 the largest attains a height of about 50 feet, with a girth of about 

 6 feet at 5 feet from the ground. On counting the concentric 

 circles, they appear to be from 100 to 120 years of age; three- 

 fourths of the wood being heart or red wood ; the timber is very 

 durable. The extent is computed at 1500 acres. The wood is 

 genei'ally used for farm purposes, and also for building houses, 

 barns, etc., throughout the glens. But the chief purpose for 

 which it is used is posts for wire fencing, for which (in the absence 

 of larch) it serves well, and lasts from seven to ten years in fair 

 older j if cut in winter and well seasoned, it will last some years 

 longer. Owing to the moist climate, barking operations have not 

 been successful. High wages and the cost of transit to the market 

 leave but a small return for the trouble and expense, and few of 

 the district proprietors have speculated in the business. Generally 

 in a dry spring the oak caterpillar is very destructive to the 

 foliage of the tree; many acres of wood. may be observed quite 

 leafless from the ravages of these voracious insects. They may 

 be seen in hundreds suspended by the silk threads by which they 

 shift from one branch to another. A day's heavy rain, however, 

 proves fatal to them. 



Birch {Betula alba). — This tree is interspersed amongst other 

 trees in the low grounds and doing well, but it is not until it 

 reaches an elevation of 500 feet that it spreads to any great extent. 

 The stronger nature of the oak gains the ascendency over the birch 

 in the low grounds, and as the oak here does not ascend to a 

 higher elevation than 500 feet, the birch, which thrives on higher 

 grounds, may at this elevation gain the ascendency over the oak 

 and other trees. It is found covering the hill-sides from 500 feet 

 to 1100 feet, and its extent is computed at 800 or 900 acres. 

 For many years a bobbin factory has been working in the dis- 

 trict, and many hundred tons of birch have been converted into 

 bobbins. The price obtained was 5 s. per ton as it stood. Lately 

 the price has advanced to 7s. 6d. per ton. The distance to the 

 nearest shipping port is 6 miles, and to the nearest thread factory 

 about 150 miles. For a number of years the caterpillar has done 

 great havoc among the birch. The larva? come into existence at 

 the time the leaves appear, and they often strip the trees on 

 which they are hatched of their entire foliage. The principal 



