THE FORMATION OF PLANTATIONS. 101 
retentive nature of the ground, as in clay soils or peat bog, a 
thorough system of lateral drains must be carried out. These are 
usually placed at the distance of from 20 to 30 feet apart, and 
should be cut with their sides perpendicular, as they are thus less 
likely to be beaten down by heavy rains, which fill up the inter- 
stices of the soil, and prevent the water from percolating through 
them freely. Their depth is usually about 18 inches to 2 feet, 
according to the requirements of the intended crop, coniferous trees 
requiring less depth of soil than hardwoods, as their roots do not 
penetrate so far into the soil as those of the latter. Where the 
ground slopes, the laterals should be cut at a more or less acute 
angle with the mains, in order to secure a proper fall, but the 
nearer they approach to a right angle with the main, the greater 
will be the area drained in proportion to their length. As before 
stated, all unnecessary drains should be avoided, while in extra 
wet places they may be cut closer than the usual distance, just as 
they may be required. 
In draining undulating ground, it is sometimes impossible to 
carry off the water by means of a main without going to great 
expense in cutting a drain far deeper than the average. Such a 
case occurs where the ground slopes from all sides, and forms a 
hollow, when, to carry off the water, a drain would have to be cut 
through the surrounding ground until a lower level was reached. 
lt is obvious that the expense incurred in doing this would be out 
of all proportion to the return expected, and therefore it would be 
more economical to run all the drains into the hollow, and allow it 
to form a pool. Should, however, a porous stratum exist within 
a reasonable distance of the surface of the hollow, a hole cut down 
to it will carry off the water before it has time to accumulate, On 
very flat ground, where a fall cannot be obtained, or where it is so 
slight as to be practically imperceptible, the best thing to do is to 
cut deep ditches at regular intervals, in which much of the water 
will collect, and leave a sufficient depth of drained soil to enable 
certain species of trees to succeed fairly well. 
Such are the principal and most frequent cases which occur in 
draining plantation ground, but exceptional ones may arise which 
will require special methods of treatment, but which it is not 
necessary to describe here. 
