MOYEABLE SCEEENS FOR WALL-ERUIT TEEES. 
S43 
If some measures are not taken to effect this, especially in clear weather, the caloric 
continues to escape, till that state of things is produced, which we term " frost," or the 
absence of heat. 
The ill effects of this are severely felt in early spring, while the leaf-buds and the 
blossoms are expanding ; and especially after they have been excited into premature growth, 
by a few hours or days of particularly fine, though unseasonable weather. 
The trees are thus exposed to a series of sudden starts and equally sudden checks, 
such as are at all times adverse to their health and well-being, but more especially so 
during the expanding and fecundating of the flowers, and the unfolding of their young and 
tender leaves. 
Thus we arrive at the conclusion, that, during the winter and earliest spring months, it 
is advisable not only to protect the trees during very severe weather, but also to shade 
them from the effects of that which approaches the opposite extreme, and when the period 
arrives, after which we deem it proper to expose them to the genial warmth of the sun, that 
it is indispensable to protect them from cold and wet. 
Perhaps no point that we have mentioned is of greater importance than keeping the 
trees dry during the winter and spring months, and especially after the flower-buds l^egin 
to expand ; as they are enabled thereby to endure a considerable amount of cold without 
sustaining any injury. 
These objects may be effected to a certain extent by the use of projecting or overhanging 
copings, which exert a very considerable protective influence over the walls, by preventing 
the upward radiation of the heat, and by throwing off the rain. 
A very remarkable instance of their advantages came under my notice in a Scotch garden 
daring the past autumn. At some time or other, a plain board had been fastened under 
the slightly projecting edge of the stone coping, along the entire length of the walls, but 
in later years it had been suffered to decay, and in two or three places it had fallen away 
altogether. 
In these particular parts of the wall, the trees were altogether destitute of fruit, and 
had a sickly, woe-begone appearance ; but where the boards were sufficiently in a state of 
preservation to answer the end for which they were designed, the trees were extremely 
healthy, and furnished with a fair crop of good fruit, I had here abundant evidence that 
these trees were under more favourable auspices than their neighbours ; and the difference 
was most remarkable on the upper part of the wall, where the boards afforded the greatest 
amount of protection. These walls were sixteen feet high. 
This instance, while it illustrates the advantage of projecting coping to a certain extent, 
shows further that of itself it is insufficient ; and that some method of protecting the whole 
surface on the wall is necessary. Various cheap expedients have been recommended from 
time to time for this purpose, but most of them are objectionable, either on account of 
their inefficiency, or their untidy appearance ; and all of them on account of the utter 
impracticability of removing or replacing them so frequently as the various changes of the 
weather render it desirable to do so. 
The best of these, however, is a covering of evergreen branches ; but if they be laid on 
sufficiently thick to answer the purpose in very severe weather, the shoots will be too 
much screened from daylight, and kept too close when it is mild. 
The buds are consequently made tender, and incapable of bearing a moderate amount 
of cold after they are uncovered ; as they unavoidably suffer if a night of extra severity 
occur after that time. 
Experience has satisfied me that the best material for covering fruit-tree walls is com- 
mon cheese cloth, or bunting ; the only objection is the expense, but in the opposite scale 
I must place its perfect efficiency, the ease with which it may be removed or applied if 
properly arranged, its neat appearance, and its durability, if ordinary care is taken to 
preserve it, when not actually in use. 
I have, during the last season, protected a small portion of the fruit walls by a com- 
bination of the projecting boarded coping, with a canvas screen, the latter being so 
constructed that the wall can be instantly covered or uncovered. 
