THE ALDER. 219 



perty of creating swamps we have repeatedly observed 

 in the Alder, and from experiments we have made, are 

 fully convinced that a plantation of Alders would soon 

 render the ground (even should it be previously of toler- 

 ably sound and dry quality,) soft and spongy, and in 

 time convert it into a decided bog. 



The Alder, therefore, in our opinion, ought never to be 

 planted in low bottom ground of a moist or wet nature, 

 (except in particular localities, such as where it is culti- 

 vated in the coppice or holt fashion, for the valuable 

 charcoal it produces) ; if introduced at all, it ought to be 

 where it cannot well retain the water in any quantity 

 around its roots. All moist and spongy land we would 

 recommend to be well drained by open cuts, and then 

 planted with trees whose roots, instead of retaining water, 

 act rather as drains ; such are some of the poplars, the 

 ash, &c, whose roots are thick, and extend horizontally 

 to a great distance on every side. 



The wood of the Alder is soft and of a homogeneous 

 texture, possessing but a moderate share of lateral and 

 longitudinal adhesion ; submerged in water or buried 

 under ground it is almost incorruptible, and on this 

 account, both in ancient and modern times, has been 

 extensively used for piles in the foundation of bridges,* 

 and other water works ; exposed to the alternation of 

 dryness and moisture it rapidly decays, as a pole or a 

 post will not stand good for more than a year, but under 

 cover and kept always dry it is very durable and remains 

 unchanged, provided it has previously undergone some 

 preparation, such as impregnation with smoke or pyro- 

 lignous acid, or has been saturated with a solution of lime 



; "" Evelyn informs us that the bridge of the Rialto, at Venice, is founded upon 

 piles of the Alder. 



