A collection of Grapes exhibited at the recent show of the Royal Horticultural Society at Oxford by Mr Speed, gardener to the Duke of Devonshire, which consisted of three remarkably fine, compact, and well-finished bunches, each of Mill Hill Hamburg, Black Hamburg, and Black Prince, gave occasion for much congratulation among the advocates and adherents of the Extension System in Grape culture. The following information relative to the production of these Grapes has recently been furnished by Mr W. P. Ayres to the 'Gardeners' Chronicle.'

"The Vines have, it appears, been planted about thirty-seven years, and occupy one of the first houses built at Chatsworth upon the ridge-and-furrow system. The border has been well raised above the surrounding soil, and Vines have been growing both inside and outside the house, but in distinct borders. For years, we are informed, the Vines had been failing; the bunches, in the first year of Mr Speed's charge, being disfigured by shanked berries, and some of them shanked altogether. The leaves, though of good size, were flaccid and poor, indicating the presence of too much moisture in the border and atmosphere, and considerable prostration of vital energy. All the Vines were in nearly the same state, the more recently-planted ones, though immensely strong, being soft and pithy - so much so that in the leading shoots an ordinary pencil might be inserted down the centre with little or no trouble. The consequence of this immaturity in the wood was the development of long, lean, loose bunches, shanked berries, and deficient colour and quality. The gardens at Chatsworth lie low and damp, considerably lower than the flood-level of the river Derwent, which runs close to it.

Consequently Mr Speed knew that the Vines were not likely to suffer from the want of water, but they were more likely to receive injury from the want of heat. To this end he at once arranged the surface of the borders, sloping them so as to afford a ready discharge at the surface for storm water. Where the bottom-heat of the borders had been disconnected it was restored, and through the parching summer of 1868 not a border, inside or outside the vineries, received any water beyond that which fell from the heavens, or an occasional surface sprinkling. The rents in the borders were such as to suggest a copious watering, but Mr Speed's object was the perfect maturation of the wood, and he knew that could only be effected by encouraging short sturdy growth, with clean well-developed foliage and buds. Air, so soon as the foliage was sufficiently hardened, was admitted by a free circulation night and day; and when the fruit was cut, heat was kept on until the leaves at last fell from the Vines from sheer maturation. Under such treatment the practised eye could soon detect that the wood was close-grained and hard as ebony, and hence in a fit state to produce well-formed bunches of finely-coloured fruit.

In 1869 the Grapes were much superior to what they had been the preceding year; and this season we should say there can scarcely be a finer series of vineries in the country. Several of the vineries at Chatsworth are stocked with old Vines, some of them planted, we believe, prior to Sir Joseph Paxton going there. In these, and also in the house to which we have specially referred, there was a confusion of branches; in fact, the leaders were laid in so closely together that it was impossible that the foliage could be properly exposed to the light. These, last winter, were reduced in number, so that now the main branches are 3 to 4 feet apart, giving ample room for lateral extension of the foliage. In the ridge-and-furrow house the inside Vines have been entirely removed, and the advantage of giving the foliage ample room for development is now conspicuously manifest. Shanked Vines are things of the past; each bunch is a compact cube of immense berries, finely hammered and coloured, and with the bloom laid on with an unsparing hand. The 264 bunches which form the crop average 3 lb. each, and some of them weighing double that weight.

The kinds are Black Hamburg and Black Prince, and below we give statistics of the crop: -

Name.

Girth 2 ft.

from ground.

Inches.

Number of rods.

Number of bunches.

Mill Hill Hamburg ...

5

2

27

Black Hamburg..

7

2

22

Black Prince..

5 1/2

3

43

Black Hamburg..

5 12

2

28

Black Hamburg..

4 3/4

2

33

Black Hamburg..

5

3

40

Black Hamburg..

6 1/4

3

46

Mill Hill Hamburg ...

5 1/2

2

25

- 264

The stems, it will be seen, are not remarkably large, but the girth below where they divide would double, perhaps treble, that of the branches. The average number of bunches is thirty-three, and taking the weight at 3 lb. each, or, for the sake of even numbers, at 100 lb. to each Vine, and the value at 5s. per pound, which they would readily bring, the value of the crop would be 200, and that from Vines which two years ago were condemned to the hatchet and the fire-pile. Nothing can be finer than the bunch which we have received; the berries are in every respect superb, and yet we are assured it was one of the smallest in the house. We regard this as one of the most extraordinary instances of the revivification of plant life which has ever been recorded, and we congratulate Mr Speed upon his well-merited success. Although there are at Chatsworth many houses of young Vines, varying from two to seven years old, not one of them is equal to this house of veterans. The extensionists may well be proud of this success, and those who visit Chatsworth (and we should advise all who have the means to do so) will find that extension is not confined to Vines, but extends to orchard-house trees, upon which may be seen splendid crops of Peaches, Nectarines, Plums, etc, the young shoots free from a single pinch, and many of them 2 to 4 feet long.

Mr Speed contends that to have weight of fruit it is indispensable to have breadth of foliage. Not a shoot will be stopped before the middle of August, and then, when the fruit begins to ripen, it will be necessary to do so to admit light and give full flavour".