SHELTER. 



35 



ducing shade, or interrupting the free 

 circulation of pure air, is a very nice 

 point in the formation of a garden. We 

 believe that more mischief has been done 

 by carrying the attempt to secure shelter 

 to an extreme extent than by the reverse. 

 No doubt shelter is necessary to break 

 the force of the east, north, and west 

 winds; but if this can be effected by 

 other means than that of forming plan- 

 tations, so much the better. Natural 

 shelter is to be looked for and obtained 

 from local circumstances, such as rising 

 grounds on all sides except the south. 

 Artificial shelter is obtained by building 

 walls, forming plantations, or taking 

 advantage of plantations already existing ; 

 but these must by no means approach so 

 near as to create shade, or to intercept 

 the rays of light and sunshine. Forsyth 

 appears to have been amongst the first 

 who traced the injurious effects of sur- 

 rounding gardens with trees to its real 

 cause ; for, after recommending shelter 

 from the north and east, to prevent the 

 blighting winds from affecting the trees, 

 he says, " At the same time there ought 

 to be a free admission of the sun and air. 

 On that account, a place surrounded by 

 woods is a very improper situation for a 

 garden, as foul stagnated air is very un- 

 favourable to vegetation ; and it is also 

 observed that blights are much more frequent 

 in such situations than in those that are 

 more open and exposed." This opinion 

 is confirmed by Mr Towers, who assigns 

 the following as the cause : " Experience 

 has amply proved," he says, " the correct- 

 ness of Forsyth's opinion on the preva- 

 lence of blight in situations surrounded 

 by woods. I believe that prevalence to 

 be dependent on the phenomena of con- 

 duction, effected by the proximity of innu- 

 merable vegetable points, by which the 

 chemical constitution of the atmosphere 

 is somewhat changed, so that the juices 

 of the plants partake of the change, and 

 acquire a saccharine quality. Insects are 

 thereby enticed, but not produced ; and 

 in every case of blight, it appears much 

 more probable that the altered or dis- 

 eased juices invite the insect than that it is 

 imported by this or that current of the air, 

 whether it blow from the east or from any 

 other point." Wherever trees abound, 

 the air becomes tainted, and malaria is 

 engendered, injurious both to vegetables 



and animals. In such situations vege- 

 table and animal matter is undergoing 

 decomposition in proportion to the den- 

 sity and extent of the plantations ; the 

 noxious gases thus formed, being pre- 

 vented from being dispersed by the 

 agency of wind, accumulate until disease 

 takes place in the foliage and tender 

 branches, and renders them fit for the 

 food of innumerable insects whose term 

 of existence appears to be almost propor- 

 tioned to the quantity of food thus pre- 

 pared for them. In forming shelter by 

 plantations, Dr Neill lays it down as a 

 rule not to be departed from, " that there 

 should be no tall trees on the south side 

 of a garden, to a very considerable dis- 

 tance." Indeed, we may add, at such a 

 distance as to render any shelter from 

 them of no avail ; "for during winter," 

 he adds, " and early spring, they fling 

 their lengthened shadows into the garden, 

 at a time when every sunbeam is valu- 

 able. On the east they must be suffi- 

 ciently removed to admit the early 

 morning rays. On the west, and more 

 particularly on the north, trees may 

 approach nearer, perhaps within less than 

 100 feet, and be more crowded — as from 

 these directions the most violent and 

 coldest winds assail us." 



The following calculations, made some 

 years ago by order of the Royal Society 

 of London, are worth the attention of 

 those who design or lay out gardens. In 

 England the prevailing winds are as 

 follows : — 



South-west, 112 days. 



North-east, 58 _ 



North-west, 50 ~ 



North, 16 ~ 



South, 18 ~ 



West, 53 ~ 



East, 26 „ 



South-east, 32 „ 



Westerly winds prevail most during July 

 and August ; north-east during January, 

 March, April, May, and June ; north-west 

 from November till March. The north- 

 east wind is less frequent during Febru- 

 ary, July, September, and December ; 

 and the north-west less frequent during 

 September and October than in any 

 other months. 



The following is the average taken 

 near Glasgow, and may serve for the 

 west of Scotland : — 



