Netting is employed to prevent the radiation of heat from walls, and the rude access of wind to trees grown upon them, as well as to prevent the ravages of birds upon currants, cherries, etc.

Netting is a very effectual preventive of cooling, for reasons which will be stated when considering Shelters generally; and in connection with that, it may be observed that it is not altogether immaterial of what substance netting is formed. Worsted is to be preferred not only because it is the most durable, but because it is the best preventive of a wall's cooling. I have found the thermometer under a hemp net sink during the night, from two to four degrees lower than that under a net of worsted, the meshes being small and of equal size in both nets. This can only be because worsted is known to be a worse conductor of heat than hemp; and, not absorbing moisture so easily, is not so liable to the cold always produced by its drying. - Principles of Gardening.

Netting will also exclude flies and other winged insects from the fruit against walls, although the meshes are more than large enough to permit their passage. Why this is the case is not very apparent, but the netting is equally efficient in keeping similar insects from intruding into rooms if there are no cross lights. If there are windows on different sides of the room, and it is to be presumed, therefore, also in a green or hot-house, nets would not be so efficient.

It is not a useless scrap of knowledge to the gardener, that one hundred square yards of netting, according to some merchants'mode ofmeasuring,will notcover more than fifty square yards of wall, for they stretch the net first longitudinally and then laterally, when making their measurement, and not in both directions at once, as the gardener must when covering his trees. Disappointment, therefore, should be avoided, when ordering new nets, by stating the size of the surface which has to be covered. This may be done without any fear of imposition.

Mr. Richardson, net maker, New Road, London, informs me, that one cwt. of old mackerel net, weighed when quite dry, will cover eight hundred square yards; and one cwt. of old herring net (smaller meshes) will cover six hundred square yards. Mr. Hulme, of Knutsford, has sent me various specimens of his nets and open canvass for inspection - some made of woollen and others of hemp: the last does not shrink after being wetted like the woollen. I prefer that with about twenty-live meshes in a square inch, at 5d. per square yard.