some fresh mould round the roots (which should be as little injured as possible), a much larger quantity of fruit, and of very superior quality, would be obtained. It is unnecessary to inform the experienced gardener, that the tree should be removed early in autumn; that its branches should be considerably retrenched, and that it should not be suffered be bear a heavy crop of fruit in the succeeding season. I have never found any species amongst the numerous and prolific genus of the aphis, which was not readily destroyed on the wall tree by covering it with a sheet of canvas, and under that introducing the smoke of tobacco. It is, however, necessary that the fumigation should be repeated twice or thrice, with intervals of four or five days. I have often seen the addition of sulphur recommended, and have known it tried, but always with fatal consequences to the tree, as well as to the insects.

The blossoms of apple and pear trees are often said, by farmers, to be blighted, when they are destroyed by insects, which breed within them, or in their fruit; and the same term is used, when the leaves have been eaten by the caterpillar but as the insects themselves, as well as the manner in which their depredations are inade, are extremely obvious, they do not properly come under our observation when treating of blights.

:

The species of parasitical plants which are found in the form of disease on other plants, appear to me greatly to exceed the number of those I have any where seen described by botanical writers. Of these the mildew is the most common and obvious. If a branch, infected with this disease, be struck

2

by the hand in calm dry weather, a quantity of white powder will be found to fly from it; and if this be received on a plate of talc, or of glass, and examined by the microscope, it will be found to consist of very numerous oval bodies, evidently organized. There is another plant similar to this in every thing but colour (being of a tawney brown), which is not unfrequently found on the leaves of young apple trees. Both these plants appear to me to be evidently species of mucor; and as much the greater number of species of this genus of plants is found to flourish in damp air, and in situations deprived of light, it may be supposed that the foregoing diseases might be prevented or removed, by placing the plants at proper distances; but I have not found this to be the case. They, however, abound most in low and sheltered situations; but they are not unfrequently seen in those of an opposite kind. The red and white mould on hops, and the black spots on stalks of wheat (the rubigo of Virgil), and many other diseases of plants, will, I think, be found to arise from the attacks of minute plants of this genus, which appears to me to possess qualities somewhat similar to the digestive powers of animals.

The most common and extensive causes of what are termed blights remain still to be described, and evidently exist in the defects and sudden variations of our unsteady climate. Whatever be the cause by which the sap is raised and propelled to the extremnities of trees, it is well known, that its progress is accelerated by heat, and that it is checked, or totally suspended, by cold; and it has been ascertained by others, as well as by myself, and indeed is

known

known to every experienced gardener, that a plant under the most skilful management, does not readily recover its former vigour, when it has been injured by exposure, for a few hours, to a temperature much below that to which it has been previously accustomed. It frequently happens in this climate, when the blossoms of our fruit trees are just expanding, that a very warm day succeeds a night whose temperature has been some degrees below the freezing point of water. In such a day the evaporation from the unfolding leaves and blossoms will be greatly increased by the agency of heat and light, whilst the supply of nourishment is in a great measure cut off by the ill effects of the preceding night. The blossoms will nevertheless unfold themselves, but will be unproductive, from the want of due nourishment; whilst the hazy appearance of the air, which almost always accompanies such weather in the spring, will induce the gardener unjustly to infer that the ill effects he observes have arisen from some quality in the air (dis tinct from excess of heat and cold), which he denominates a blight.

The best defence against this kind of weather for wall trees, that I believe has yet been tried, is a covering of a double and triple net; for by this the tree is in some degree protected from frost; and the excess of evaporation, in the succeeding day, is in a very considerable degree prevented. Lightning is supposed by many to be very highly injurious to the blossoms of trees; but. I believe that the ill effects which appear sometimes to accompany it may be more justly attributed to excessive heat. The careful gardener often covers his trees with mats, or

something of this kind; and by a most totally depriving the trees of light, creates that blight which he is anxious to exclude.

As the blossoms of every tree art formed during the preceding sum mer and autumn, they will evidenty be more perfect in proportion as those seasons have been favourable, and as the management of the gar dener has been judicious; and as the power of bearing unfavourable weather will be proportional to their vigour, and to the maturity of the annual wood, through which the sap passes to support them, the gar dener should be (though he rarely is) extremely attentive to keep his trees in such a state, and the branches at such distances from each other, that they may receive the greatest possible benefit from the portion of light and heat which our shadowy climate affords them. It frequently happens in pruning, that too much bearing wood is left on the tree. Every gardener ought to know, that where a hundred fruits are a sufficient crop for a tree, he has a better chance to obtain that hundred from one thousand blossoms, to which the whole nourishment of the tree is directed, than when the same quantity of nourishment has to support a hundred thousand.

In standard fruit trees, where no advantages can be derived from covering them, much may be done by the judicious application of the pruning knife. The branches of a tree of this kind ought to be much thinned towards their extremities, so that the light may be admitted into the centre of the tree; but the internal parts of it should never be so thin as to admit of a free current of air through it. When a tree has been properly pruned, blossoms and

fruit will be found on every part of it; and, in unseasonable seasons, the internal blossoms will receive protection from the external branches, which will be unfruitful.

It is particularly the interest of every planter, to take care that the varieties of fruit which he plants be sufficiently hardy for the situation in which he places them; for if this be not attended to, little benefit will be derived from the foregoing observations.

Method of preserving fresh Water sweet during long Voyages. By Samuel Bentham, Esq. of Queen's square, Westminster. From the Transactions of the Society for the Encouragement of Arts, Manufactures, and Commerce.

HE mode in which I conceived fresh water might be preserved sweet, was merely by keeping it in vessels of which the interior lining at least should be of such a substance as should not be acted upon by the water, so as to become a cause of contamination. Accordingly, on board two ships, the greater part of the water was kept, not in casks, but in cases or tanks, which, though they were made of wood, on account of strength, were lined with metallic plates, of the kind manufactured by Mr. Charles Wyatt, of Bridge-street, under the denomination of tinned copper-sheets; and the junctures of the plates or sheets were soldered together, so that the lightness of the cases depended entirely on the lining, the water having no where access to the wood. The shape of these cases was adapted to that of the hold of the ship, some of them being made to fit close under the VOL. XLIV.

platform, by which means the quan tity of water stowed was considerably greater than could have been' stowed, in the same space, by means of casks; and thereby the stowage room on board ship was very much increased.

manner

The quantity of water kept in this on board each ship, was about forty tons, divided into sixteen tanks; and there was likewise, on board each of the ships, about thirty tons stowed in casks as usual.

As the stowing the water in tanks was considered as an experiment, the water in the casks was used in preference; that in the tanks being reserved for occasions of necessity, excepting that a smail quantity of it was used occasionally for the purpose of ascertaining its purity, or

when the water in the casks was deemed, when compared with that in tanks, too bad for use.

The water in thirteen of the tanks, on board one ship, and in all the tanks on board the other, was always as sweet as when first taken from the source; but in the other three of the tanks, on board one ship, the water was found to be more or less tainted as in the casks. This difference, however, is easily accounted for, by supposing that the water of these tanks was contaminated before it was put into them; for, in fact, the whole of the water was brought on board in casks, for the purpose of filling the tanks, and no particular care was taken to taste the water at the time of taking it on board.

After the water kept in this manner had remained on board a length of time, which was deemed sufficient for experiment, it was used out, and the tanks were replenished as occasion required: but in some

3 E

of

e no means have been found to et their course. But if such ns could be discovered, what ld become of camps, cannon, resses, and the whole art of war? But if we have not succeeded steering the balloon, and even e it impossible to attain that ect, the case is different with the ng boat, which can be conducted ler water in the same manner as on the surface. It has the advane of sailing like a common boat, I also of diving when it is purd. With these qualities it is fit carrying secret orders, to succour lockaded port, and to examine the ce and position of an enemy in ir own harbours. These are sure

and evident benefits, which the diving boat at present promises. But who can see all the consequences of this discovery, or the improvements of which it is susceptible? Mr. Ful ton has already added to his boat a machine, by means of which he blew up a large boat in the port of Brest; and if, by future experiments, the same effect could be produced on frigates or ships of the line, what will become of maritime wars, and where will sailors be found to man ships of war, when it is a physical certainty, that they may every moment be blown into the air by means of a diving boat, against which no human foresight can guard them?"