It stands to reason that were our summers warmer we should be able to grow grapes successfully on open walls; it is therefore probable that a new grape bag, the invention of M. Pelletier, 20 Rue de la Banque, Paris, intended to serve a double purpose, viz., protecting the fruit and hastening its maturity, will, when it becomes known, be welcomed in this country. It consists of a square of curved glass so fixed to the bag that the sun's rays are concentrated upon the fruit, thereby rendering its ripening more certain in addition to improving its quality generally. The glass is affixed to the bag by means of a light iron wire support. It covers that portion of it next the sun, so that it increases the amount of light and warms the grapes without scorching them, a result due to the convexity of the glass and the layer of air between it and the bag. M. Pelletier had the idea of rendering these bags cheaper by employing plain squares instead of curved ones, but the advantage thus obtained was more than counterbalanced by their comparative inefficacy.
In practice it was found that the curved squares gave an average of 7° more than the straight ones, while there was a difference of 10° when the bags alone were used, thus plainly demonstrating the practical value of the invention.
Whether these glass-fronted bags would have much value in the case of grapes grown under glass in the ordinary way is a question that can only be determined by actual experiment; but where the vines are on walls, either under glass screens or in the open air, so that the bunches feel the full force of the sun's rays, there can be no doubt as to their utility, and it is probable that by their aid many of the continental varieties which we do not now attempt to grow in the open, and which are scarcely worthy of a place under glass, might be well ripened. At any rate we ought to give anything a fair trial which may serve to neutralize, if only in a slight degree, the uncertainty of our summers. As it is, we have only about two varieties of grapes, and these not the best of the hardy kinds, as regards flavor and appearance, that ripen out of doors, and even these do not always succeed. We know next to nothing of the many really well-flavored kinds which are so much appreciated in many parts of the Continent. The fact is, our outdoor culture of grapes offers a striking contrast to that practiced under glass, and although our comparatively sunless and moist climate affords some excuse for our shortcomings in this respect, there is no valid reason for the utter want of good culture which is to be observed in a general way.
Grape Bag Open.
Given intelligent training, constant care in stopping the laterals, and checking mildew as well as thinning the berries, allowing each bunch to get the full benefit of sun and air, and I believe good eatable grapes would often be obtained even in summers marked by a low average temperature.
Grape Bag Closed.
If, moreover, to a good system of culture we add some such mechanical contrivance as that under notice whereby the bunches enjoy an average warmth some 10° higher than they otherwise would do, we not only insure the grapes coming to perfection in favored districts, but outdoor culture might probably be practiced in higher latitudes than is now practicable.
CURVED GLASS FOR FRONT OF BAG.
The improved grape bag would also offer great facilities for destroying mildew or guarantee the grapes against its attacks, as a light dusting administered as soon as the berries were fairly formed would suffice for the season, as owing to the glass protecting the berries from driving rains, which often accompany south or south-west winds in summer and autumn, the sulphur would not be washed off.
CURVED GLASS FIXED ON BAG.
The inventor claims, and we should say with just reason, that these glass fronted bags would be found equally serviceable for the ripening of pears and other choice fruits, and with a view to their being employed for such a purpose, he has had them made of varying sizes and shapes. In conclusion, it may be observed that, in addition to advancing the maturity of the fruits to which they are applied, they also serve to preserve them from falling to the ground when ripe.--J. COBNHILL, in the Garden.