SELECTION OF SITE 



97 



is a great disadvantage. The reason for this will be obvious from 

 a consideration of the accompanying sketch (Fig. 44). 



It will be seen that if SPN represents a piece of ground one 

 half of which slopes from the ridge P in the southerly direction 

 PS, and the other half slopes in the northerly direction PN, 

 while the area of the ground on the two slopes is the same, the 

 total amount of sunlight and heat which falls on the ground and 

 is represented by RNSQ, is not equally divided between the 

 two slopes more than half (represented by OPSQ) falling on 

 the southern slope, and a correspondingly diminished quantity 

 (represented by OPNR) falling on 

 the northern half. The angle of 

 incidence of the sun's rays is in- 

 creased where the ground has a 

 southern slope, and this is in fact 

 equivalent to a change in latitude. 

 If the garden ground is horizontal 

 it must not be in an exposed situa- 

 tion, for it is impossible to obtain 

 satisfactory results when plants are 

 open to cold sweeping winds from 

 the north or east. If such a situa- 

 tion is unavoidable, steps should 

 be taken at the outset to provide 

 shelter in those directions either 

 by planting a thickset hedge of 



quickly growing plants or by making a plantation of trees to form 

 a wind-break. For the purpose of increasing the educational value 

 of the garden the latter is the better plan, because a variety of trees 

 may be employed which will afford useful material for nature-study 

 lessons. A very good arrangement would be to plant one row of 

 British trees on the outside, and on the inner side of these, alter- 

 nating with them, a row of plum trees, which are, for the most 

 part, very hardy and cold resisting. While on the subject of trees, 

 it may be useful to point out that large trees like the oak, elm, ash, 

 and beech cover a very considerable area both above and below 

 ground ; their dense foliage intercepts a great deal of the rainfall 

 which evaporates from the surfaces of the leaves instead of 



VOL. V. 7 



FIG. 45. An Error in Planting. Show- 

 ing the mistake, or result of planting 

 too near to large trees or shrubs, as 

 the roots of the latter rob the plants 

 of food. A, herbaceous plants ; B, 

 tree roots. 



