AGRICULTURAL METEOROLOGY. aa 
propagates a proportion of young wood every year, and does not suffer 
any to remain on the trees older than six or seven years.* 
In 1820 the sudden change from a temperature of 12° above zero to 
one of 14° below, destroyed, in January, the greater part of the olive trees 
in Provence, France. Mr. Joseph Jean, proprietor of an olive-orchard 
of one hundred trees, by a process which he invented, saved seventy- 
six of the oldest. In the month of April he cut all the branches within 
some distance of the top of the trunk; he smoked the trees in the ordi- 
nary manner, and buried fresh herbage at their feet ; he then cut off all 
the sprouts which were manifested at the ends of the remaining 
branches. The new sprouts of the first year grew to one meter, or about 
three feet, and redoubled their growth in the second season. In the 
third year he had already regained a quarter of his accustomed har- 
vest. Raibaud-Lauge has given the following explanation: The sap of 
the partly-frozen trees, maintained abundant by the dampness of the 
herbage and the suppressing of the sprouts springing from near the 
roots, is forced to flow upward into the trunk, and the tree is thus saved 
from the injurious effects of the frost. t 
The distinguished horticulturist, Mr. Thomas Andrew Knight, says: 
Among the various methods of protecting the blossoms of wall-trees from frost, 
which are adopted by: gardeners, it must be admitted that the most efficient are those 
by which the trees are thickly covered during the night, and fully exposed during the 
day ; andif this kind of protection be given to peach and nectarine trees very early in 
the spring, it not only preserves the blossoms, but it also prevents the appearance of 
blistered leaves, which are generally abundant in cold and unfavorable seasons. 
Woolen nets, or a patent imitation of netting, constitute the best material for wall-tree 
covering ; but the meshes should be sufficiently wide to permit the ingress of bees, for 
the pistils of the blossoms of almost all fruit trees are not in the best state to receive 
. the pollen till the anthers of these blossoms have been expanded, and the number ef 
blossoms which are rendered productive of fruit by their own proper pollen is not, I 
have reason to believe, very great. The exclusion of honey-gathering insects is conse- 
quently in most cases very injurious. 
The material which I employ consists of small branches of the birch-tree, about two 
feet in length, collected as soon as the leaves have become full grown, at the end of 
June; these are preserved under cover till the following spring, when they have be- 
come perfectly dry, which is a very important circumstance. They are then secured to 
the walls by a few nails and shreds, with their points hanging perpendicularly down- 
ward, their upper and thick ends being in contact with the wall, and the opposite 
slender extremities projecting eight or ten inches from it. This position of the cover- 
ing material appears to me to be an extremely advantageous one, and I have constantly 
employed it in this manner more than ten years. Every year a very large portion of 
my blossoms has escaped injury under its protection. As to the quantity to be used, 
with advantage, it is left to the discretion of the gardener. If the situation of his 
garden be low, he may cover his trees more closely than if it be high; but the covering 
should never be so thick or close as to prevent a large portion of the blossoms being 
visible to a person passing within a few feet of the wall; under such circumstances 
almost every blossom will in some part of the day receive a portion of the solar rays. 
As the danger to be apprehended from frost diminishes, and the quantity of young 
shoots and foliage increases, the covering material should be taken away at successive 
periods and in small quantities. My experience has been confined to the use of the 
slender branches of the birch-tree, but bunches of other trees with small leaves, such 
as the hawthorn or hornbeam, might, I believe, be employed with success, though I 
give decided preference to those of the birch. t 
Jeger has obtained the greatest success by the use of well-water for _ 
sprinkling frozen plants, but it is necessary to apply it when the ther- 
mometer stands about 1° below zero,§ because if we sprinkle the plants 
*Transactions of the Horticultural Society of London, 1818, vol. ii, p. 228. 
t Mem. d’Agriculture, Paris, 1823, pp. 407-36; Annales de l’Agriculture Frangaise, 
Paris, 1823, vol. xxii, p. 355-83; Remarks of H. Laure, in Bulletin de la Société 
@ Agriculture du Département du Var. Draguignan, 1824, No. xv; Report of Boscip, 
in Annales de l’Agriculture Fran¢gaise. Paris, 1823, vol. xxii, pp. 383-86. 
t Transactions of the Horticultural Society of London, 1824, vol. 5, pp. 505-8. 
§ Centigrade, equivalent to 32° Fahrenheit, or freezing point. 
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