WE have recently received letters from various localities, stating that Grapes that should have hung in good condition on the Vines for a long time have moulded and dropped from their stalks. In one case, the whole crop of Muscats was literally lost. Considering the general dampness and want of sunshine which characterised the Grape-ripening months of August and September, and the heavy rainfall, it is not by any means surprising that Grapes should, in many instances, not keep well. There cannot be a doubt that the successful keeping of Grapes throughout the winter depends very much on the circumstances under which they are ripened. At the same time, very much depends on the way in which they are managed after they are ripe, especially from the middle of October up to the time that the Vines shed their leaves and become comparatively inactive. We know, from the loss that has occurred to several, that this is a subject that may be discussed with profit to some of our readers; and, after opening the subject with a few remarks, we will be very glad to have the experience and ideas of our correspondents.

Glancing first at the difference which certain treatment in the ripening of Grapes makes to their hanging for a length of time after they are ripe, with the greatest possible freshness and the least possible loss from damping and decay, we consider it of great importance that they should be grown and ripened under the influence of as much light as possible, and freely subjected to a circulation of dry warm air.

The character of Grapes grown under the influence of a moist, steamy atmosphere, with a less amount of ventilation, is very different to those managed on the drier and more airy system. There is not only a flabbiness and dropsical character produced in the whole growth of Vines under close moist treatment, but the fruit, as all experienced Grape-growers know, partakes of this characteristic. The berries may perhaps be larger, but they will be less fleshy and more tender skinned. In short, a predisposition to ferment and rot when the trying season comes is imparted to them. On the other hand, when cultivated on the dry and airy system, the berries are firmer, and the whole system of the Vine gets into a more matured or ripened state. We consider it of much importance that Grape crops - especially those in the northern parts of our kingdom - should be completely ripe by the first week of October, and finished, too, under the influence of a circulation of dry warm air, produced, if the season render it necessary, by fire-heat. Unless Grapes are thoroughly ripened, and the sugary matter in them well developed, they are much more likely to ferment under the influence of too much moisture at the roots of the Vines or in the air of the Vinery. Grapes ripened in a light and large airy Vinery are much more likely to be ripened off in that condition which not only constitutes them better Grapes, but also much easier of keeping well after they are ripe.

Turning now to the leading points of management in keeping Grapes after they are quite ripe: there can be no doubt that the most disastrous failures have occurred from the want of studying the laws of heat and moisture in their relation to the Grapes. If water stagnates about the roots of Vines in winter, that alone is enough to cause the Grapes to mould and decay. But the more general cause of failure arises from moisture settling on the bunches. The drainage of the border should be thorough. Not only so, but, in wet localities especially, it will be an advantage to throw heavy rains off the border by means of wooden shutters or tarpauling, after the middle of October at the latest. Still, and although this precaution of protection from rains is desirable, we could point to many cases of the most perfect success where such protection was never adopted, but where the borders were well drained.

The chief secret of success lies in the ventilation and firing of the Vinery; and when these points are judiciously carried out, Grapes often keep well, while other matters may only be second-rate. First, it is necessary that the berries be more severely thinned than for summer Grapes, so that the air can circulate about the whole of the berries; for it is damp settling on the berries that produces the mischief, and, as a consequence, this is the thing by all means to avoid. Hence the too common practice of ventilating freely on damp foggy days is a great mistake. This is simply drawing a volume of air surcharged with moisture through the Vinery, to be condensed on the bunches and Vines. Fire-heat in conjunction with ventilation on such days does not mend the matter; it rather increases it, by causing a more rapid current of damp air to pass through the Vinery. The thing to do is to keep the house close, especially at the front, during foggy damp weather; to keep the temperature about 45°, and just a chink of air at the top, but, if possible, in such a manner that damp does not fall into the house: hence the value of wet-weather ventilation, as it is called.

The time to fire and ventilate Vines freely is on bright dry days, when it is certain that in the circulation more damp can be expelled than there is admitted, and always dropping the heat to the minimum of 45° to 50° before night. All inside surfaces should be dry after the 1st of October, and never moistened, and a low stagnant temperature should be avoided. The result of having the air and Grapes inside the Vinery as cold as the external atmosphere, or nearly so, is, that the moisture that is admitted with the air from the outside condenses immediately on the surface of the berries; whereas, when they are warmer than the external air, they do not act as condensers. This law of heat and moisture is very strikingly exemplified by walking into a moist stove with a piece of smooth cold wood or slate, or, in fact, any cold, hard, smooth substance. The result is, that it is immediately covered with dew-drops. The cold substance has condensed the particles of moisture in the warm air - and just so the Grapes act to their own destruction. The temperature should therefore be kept steadily above that of the external air, to prevent this destructive result.

We know of a whole Vinery full of Grapes being lost last year by an amateur, simply by his keeping the front and top ventilation always open in the dampest weather, and so subjecting the Grapes to a cold vapour bath.

There is one particularly ticklish time or stage when Grapes are the most difficult to keep, and that is, just as the foliage begins to change to the "sere and yellow leaf." Some varieties of Grapes are then very subject to go wrong under the best treatment. Small white stars of decay, cutting into the skins and radiating from a centre like a star, first appear, and soon the whole berry goes wrong.. The first signs of this should incite to more vigilance. The affected berries should be at once removed, and all the laterals where there are any; and where there are not, a portion of the foliage should be removed, so as to let light and air play more freely about the bunches. We have known the progress of decay arrested by removing part of the leaves while they were comparatively fresh. No dcubt the removal of part of the foliage helps to paralyse the roots, and prevent their pumping up a superabundant supply of sap to the Grapes in a crude state; at all events, it admits a freer circulation of air, and a stagnant atmosphere is an evil.

We have kept Grapes this season till very lately in a low sunk pit under obscured glass, and, we may say, under a constant downpour of rain, by simply keeping the pipes constantly warm, and surfaces perfectly dry, so that the Grapes were always too warm to condense moisture. Out of 300 bunches under such conditions, not 2 lb. were lost by decay; while if the fire-heat had not been constant, and a cold stagnant air allowed, we are certain the result would have been the very reverse.