94 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY, 
proprietor. When formed solely for the purpose of giving shelter 
to adjacent lands, however, it is sometimes necessary to lay off 
fresh boundaries altogether, in order to break as much of the wind 
as possible, and give shelter to a larger area, As winds usually 
acquire their objectionable character from the surface over which 
they have previously passed, whether snow-covered mountains, 
hot deserts, or wide oceans, it is evident that the wind most 
dreaded in one locality may be perfectly harmless in another, 
although coming from the same quarter of the compass ; therefore 
no general rule can be laid down as to the particular direction in 
which a shelter-belt should extend, all depending upon the 
direction from which the wind comes that it is desired to break. 
The shape of the belt must depend a great deal upon the extent 
of ground it is intended to shelter, and the conformation of the 
ground. When it is intended to give thorough shelter to a 
limited area, that of an acute angle is probably the best, with the 
apex presented to the wind. When given such a shape it has a 
greater tendency to divert the current of air in two directions, 
one along each side of the belt respectively ; and it also gives more 
efficient shelter to the ground immediately to the leeward of the 
belt, by protecting the two sides nearly parallel to the direction 
of the wind, forming a cove or recess, an invaluable situation for 
pasturing cattle. When it is desired to shelter a larger area 
without increasing the size of the belt, the angle may be increased 
until it results in nearly a straight line, the convex side of which 
should always be presented to the wind, otherwise it would have 
a tendency to concentrate the force of the wind into the corner 
formed by the junction of the two sides, thereby increasing its 
force at that particular spot. The length of such a belt is inde- 
finite, according to the requirements and extent of the ground to 
be sheltered, but the breadth at the point of impact should never 
be less than from one to two hundred yards if it is intended 
to produce timber, and either retaining that breadth throughout, 
or gradually decreasing towards the leeward extremities. 
In laying off plantation boundaries which are intended for the 
production of timber, we have to be guided by different principles. 
Here we have to consider how best to prevent strong or prevailing 
winds from injuriously affecting the health and growth of the 
trees and uprooting them after a severe frost or heavy rain, both 
of which loosen the ground and render the trees more liable to be 
overturned, So long as a plantation remains intact, and is not 
