tan in the spring, when the Hence an old act of parlia

but to contain a larger proportion of sap is rising, than at other seasons. ment, now in force, ordains that all oak, except for the purpose of building, shall be felled in the spring. Whether doors, posts and rails, paling, barrel-staves, &c. come under the denomination of building, it may be difficult to say; but it seems at first view highly to be lamented that any law should impose an obligation to destroy a valuable species of property. It would indeed be matter of peculiar regret, if an impolitic and avaricious spirit should induce the owners of oak forests to extend the same principle to the timber employed in the construction of great machines, and more especially the British navy.

Various means have been employed in order to remove the tendency to the dry-rot in trees so felled. Thus they have been long exposed to the rain, or steeped, or even sometimes boiled in water, and then dried by artificial heat. These means do not however appear to have been successful in entirely washing out the fermentible sap, which therefore makes them much more subject to the decay of which we are treating. It may however still be doubted whether it acts in any other way than by furnishing a disposition, which requires to be called into action by the same cause which operates in all other cases, moisture.

In proof of what I have stated, I have been informed by one of our Vice-Presidents, that in a large vat or set of vats for beer, belonging to him, the staves formed of oak 2 1-2 inches thick notwithstanding they were previously steeped in hot water, and then thoroughly dried, in a very short time underwent the dryrot, while others in the same situation continued unchanged five or ten times that period. It is highly worthy of remark, that the outside of these staves, which was painted, continued sound and that the decay began on the inside, where, from the vats being at different times more or less filled, they were subject to the joint and successive influence of moisture and air.

I have mentioned above, that the putrefactive fermentation cannot take place except in certain temperatures, the lowest of which, according to Thompson, must be but little below 45 de

grees of Fahrenheit's thermometer, and the highest degree which produces dryness by evaporation. The temperaturé most conducive to this effect has not, so far as I know, been ascertained, though much useful information on this head might be obtained from a set of well-conducted experiments.

The following then appears to be the whole theory of the dry rot; that it is a more or less rapid decomposition of the substance of the wood, from moisture deposited on it by condensation, to the action of which it is more disposed in certain situations than in others; and that this moisture operates most quickly on wood which most abounds with the saccharine or fermentible principles of the sap. Let us see how this theory corresponds with the best known means of prevention, and what more effectual measures it may suggest.

The first point is certainly to choose timber properly felled and well dried. And here, in order to prevent the injudicious fall of large oak timber, it may be of consequence so know that the bark! of such timber contains much less tan than that of the younger and more succulent wood; and that this principle, together with the proper extractive matter, is considerably more abundant in the bark of the Leicester or Huntingdon willow, than in that of any oak. According to the experiments of Mr. Davy, 7 1-2 pounds of the former will go as far in tanning leather as 9 or 10 pounds of the latter. It has however been asserted, that if an oak, or any other tree, which is stripped of its bark, be suffered to stand two or three years before it is felled, the wood will have acquired a very great degree of strength and durability.

Next, where it is practicable, a current of air should be frequently made to pass along the surface of the wood. This expedient seems to have been particularly attended to by the inge nious architects of our Gothic churches, who are said, with that view, to have left various openings in the walls between the two roofs of those edifices. In order also to promote evaporation, a certain degree of heat, such as that of air heated by the sun or fire, should, if possible, be from time to time applied. Cellars themselves ought to have some communication with the outward

air by means of windows and shutters, or trap-doors: and that these may be for a short time opened in proper weather, so as to have a draught of air; and that no very low degree of temperature is necessary for the preservation of fermented liquors, provided that temperature be uniform, is evident from the practicability of keeping wine extremely well in cellars which are not damp, and in which, therefore, one or both of these circumstances must have taken place.

The destruction of wainscoting may be long deferred by keeping in the apartment suitable fires.

Lastly, the dry-rot may in all cases be infallibly prevented where it is practicable to cover the surface of the wood, properly dried, with a varnish which is impenetrable and indestructable by water. With this view, two or three coats of the composition before described should be laid on the dry wood, before it is erected or put together, and a third or fourth after it is put in its place; and proper means should be taken thoroughly to dry each successive coat of varnish. In situations of this kind, what means of preservation are necessary must be employed at first; as it seems scarcely possible to renew them on fixed timber with any chance of benefit.

I do not know whether in very damp situations, surrounded with stagnant air, these varnishes would not in time admit of the growth of fungi or mould. The brimstone might be supposed sufficient to preclude that effect; but, if we believe Braconnet, seeds of the white mustard sown in pure flower of brimstone, and well watered, became vigorous plants, which flowered and produced effective seeds. It is certain, however, that the essential oil of turpentine will act as a poison on growing vegetables; and perhaps the same property may exist in rosin, which seems to be a similar essential oil, united with a certain proportion of oxygen.

It is however highly probable, that the union of the brimstone may have another good effect, which is to prevent one of the causes of the destruction of timber which I have before mentioned, the depredations of insects, Whoever would learn the

havoc which certain animals of this kind are capable of making in hot countries, would do well to read Sineathman's description of the Termes, or White Ant, originally published in the Philo-sophical Transactions, and from thence abridged into the English Encyclopedia Britannica, and other collections. In this country we know little of such ravages. Mischief, however, of this kind does sometimes occur, and may be the work of various animals, a particular account of which may be met with in the fifth vòlume of the Transactions of the Linnean Society.

I am informed, that in India, a circle of Lord Dundonald's coal-tar drawn on the floor round boxes and other furniture, will effectually preserve them and their contents from the depredations of the white ant.

It appears that most insects are fond of sugar and mucilage; which is the probable reason why that wood is most subject to be penetrated by worms, which is felled when it most abounds with sap. In such cases, it might be well to try the effects of washing the wood, previously to the use of the varnish, with a solution of arsenic in hot water, in the proportion of 1 lb. to 10 gallons; or with a strong decoction of coloquintida or bitter apple, or white hellebore; after which the wood must be completely dried before the application of the varnish in the manner before directed. All these preparations are extremely cheap, and are either destructive or offensive to insects, and therefore will, probably, be an effec tual defence against any injury from that cause.

ON THE PRINCIPLES

OF IMPROVING

THE BREED OF DOMESTIC ANIMALS,

EVERY one, whose opportunities have permitted, must have remarked, that the agriculture of Pennsylvania has very materially improved in the course of the last twenty years. This

change has been effected by the free use of lime, gypsum, and the introduction of green and root crops, and their alternation with those of grain, by which means abundant food for all domestic animals is furnished, manure rapidly accumulated, and the strength of the land kept up. It cannot however be denied, that in all kinds of farm cattle, there is much room for improvement, and that in respect to fine neat cattle, our deficiency is very great. With a view therefore to assist those who are anxious to undertake the important and profitable measure of improving their stock, the following hints are given. They are the result of remarks of professed breeders and improvers in England,† tested by the experience and observations of the Editor, and other members of the Cattle Society of Pennsylvania.

- Until about fifty years since, no attempt had been made to change the state of farm cattle in England. Before that time, BO country possessed animals of worse forms. Size was the only object of consideration, and form was never taken into view. Hence large big boned, coarse headed, narrow rumped animals were the fashionable stock of the day. Some of those worthless beasts were imported into the United States before the revolutionary war, but they are now happily extinct. They are still abundant in England, as appears by Mr. Nicholson's letter in page 295.

A few ingenious and observing men, perceiving the loss sustained in feeding such animals, commenced the attempt to alter their forms, selecting and breeding from what they deemed the best shaped without regard to bulk. Mr. Bakewell of Dishley, in the county of Leicester, continued to advance the desirable properties of the race upon which the experiment was first made,

For a full account of the fertilizing effects of gypsum on grass, and on other vegetables, its mode of application, &c. see the Treatise of Mr. Peters on Gypsum, the Memoirs of the Agricultural Society of Philadelphia, vols. 1— 2. and the Domestic Encyclopædia, Philadelphia edition.-For remarks on lime as a manure, see the two last mentioned works.

↑ The authorities consulted, besides those quoted, are Lord Somerville, Cline on the form of animals; Lawrence on Cattle, and Sir John Sinclair.