Изображения страниц

The second part of the book is illustrated with a map coloured to show the districts drained by the several rivers. Here the author conducts the tourist about from dale to dale, pointing out the beauties of the scenery, its geological aspects, shows where rare plants may be gathered, and gives us their names; reminds us now and then of what has been sung by Wordsworth and Scott; and is altogether a pleasant and valuable companion.

The third part, on botany proper, is prefaced by a summary of conditions affecting a flora; and then follows a catalogue of the species. Here the author indicates in which of the drainage districts his plant is found, its range in height, the conditions under which it occurs, and the localities where it may be met with.

And, finally, there is an appendix giving an account of all the books, papers, and herbaria relating to the North Yorkshire flora, and an index of localities, and another of the genera of plants.

With all this material so systematically arranged, it is impossible not to regret that the author has not himself given some outline of those conclusions to which it cannot but have led. We would fain have learnt what variations the plant growing on the mountain-top presents when compared with the same species from the vale. We would gladly have been told whether the plant growing on clay was distinguishable from the same species inhabiting sandstone or limestone. We would have discovered what bearing all these external influencing conditions have on the flora, and what the significance of the limited range of a species may be. Perhaps Mr. Baker may yet be induced to give in some other form the results of his experience.

In conclusion, we can only urge all who go to North Yorkshire, and know the rudiments of botany or geology, to avail themselves thankfully of so luminous a guide as Mr. Baker.




CULTIVATION OF COTTON IN FRANCE.-The Société d'Acclimatation of Paris has for some time been engaged in encouraging the experiment of growing cotton in France, and the results now reported are certainly deserving of great attention. The Marquis de Tournes writes to the society that he is convinced that the cotton-plant may easily be acclimatized on the alluvial plains of Provence. "In spite of detestable weather," he says, "our crop surpasses that of last year; samples have been submitted to Messrs. Schlumberger, of Gnebwiller, who report that, allowance being made for ginning, our long staple cotton may be set down as worth ten francs per kilogramme [about 3s. 8d. per lb.], and our short staple at six franes and a half [2s. 4d. per lb.]!"

The Sériciculture Practique, published in the Vaucluse, says: "The 150 kilogrammes of seed received by the Society of Agriculture has not been sufficient to supply the demands of cultivators, and a further supply has been sent from Algeria, with valuable hints as to the modes of cultivation."

In the neighbourhood of Avignon the experiment is being carried out with energy by the Agricultural Society and many private individuals.

The results above given certainly surpass all expectation, and it will be an equally curious and important result if the difficulties in America should give rise to the practical cultivation of cotton in the south of France. There remains, however, the grand question of the cost of production; and it will be strange indeed should it turn out that France can compete successfully with India, Egypt, and her own settlements in Algeria.

It is well to mention, in connection with this subject, that M. Louis Reybaud, who was commissioned by the Academy of Moral and Political Science to report on the condition of the textile manufactures, arrives at the conclusion that it will not be safe to depend on cotton in future, and that the only safe course will be to use all possible efforts to replace it, to a large extent, by flax and wool!

THE MANUFACTURE OF STEEL.-M. Caron has communicated to the Academy of Sciences of Paris the result of a series of important experiments made with the view to ascertain the part actually played by manganese in the fabrication of steel, and the results are given in a few words :-First, that the phosphorus of the iron is not carried off by the manganese; second, that sulphur, even without refining, will disappear in presence of manganese; and, third, that silica is in a great part removed by the manganese.


conclusions, says M. Caron, are confirmed by practice, for the minerals which yield the best steel frequently contain sulphur, but never phosphorus; and moreover it is remarkable that, although they contain coppery pyrites, the iron derived from them never contains sulphur. Manganese has, beyond question, the effect of rendering steel better and, above all, more durable; and this power is not difficult of explanation. When a sufficient quantity of manganese is added to grey cast-iron, of which the carbon is principally in a free condition, the result is white iron, in which the carbon is almost entirely in a state of combination. The effect is the same in the case of steel: a very small quantity of manganese is sufficient to retain the carbon in a state of combination, and to give to the metal those conditions which characterize steel of good quality. But the steel should never contain more than one two-hundredth part of its own weight of manganese, otherwise it becomes hard and brittle, the fracture assumes a crystalline appearance, and the metal loses a great part of its tenacity. Manganese has, moreover, the property of rendering steel capable of being welded, which is not so without its aid. It is not uncommon, in order to improve the quality of iron, to mix ordinary and manganesian iron together, and then to refine the mixture; and M. Caron says that he has learnt by experience that the purifying power of the manganesian iron is in direct proportion to the amount of the manganese present. It is therefore most important, he adds, to reduce the manganesian ores in such a manner as to retain the largest possible quantity of manganese in the iron. The spathic iron ore of Siegen contains 15 to 20 parts of manganese to 100 of iron, and yet the cast-iron derived from this mineral only contains from 6 to 7 per cent. of manganese; but if, by a modification of the furnaces, or a change in the nature or proportions of the fluxes, the amount of the manganese in the iron could be raised to 10 per cent., it is certain that cast-iron of very great commercial value would be the result.* M. Caron promises further communications on this very important subject in a short time.

PRESERVATION OF WOOD.-Considerable attention has been given of late to this important subject in France and Belgium, and M. Pottier, of the University of Ghent, has recently presented a memoir on the effect of the creosote process to the Royal Academy of Belgium. He therein details his experiments with the heavy oil of gas-tar, and arrives at the conclusion that of the various ingredients which enter into its composition, the volatile hydrocarbons, aniline, phenic acid, and napthaline possess no preservative qualities whatever; and that the green oil which is produced by the distillation of gas-tar at a temperature of about 570° is that which is most effective in preventing the destruction of wood.

M. Lapparent, Director of Naval Construction in France, has been engaged in investigating the subject from another point of view. Having been impressed with the effect of the old method of charring posts and other timber to be fixed in the ground, he made a series of experiments on the causes of the destruction of timber and the action of carbonization as

* See also Summary of Metallurgy.

a preventive; and arrived at the conclusion that the practice alluded to contained the elements of a very valuable means of preservation. M. Lapparent believes that the effect may be produced without any material destruction of the wood, and that all that is required is a very thin coating or deposit of empyreumatic products, or, in other words, that the necessary carbonization may be obtained without any alteration of the surface of the wood, or any diminution of the sharpness of the angles. He makes use of a jet of gas, mingled with a current of compressed air, in order at once to produce a more active combustion, and to give a more decided direction to the flame. It matters not what gas is used so that it give a great heat in burning. When the pieces of wood to be carbonized are small or light, they are passed over the flame of gas by hand, but in dealing with heavy timber, or with pieces fixed in position-such, for instance, as those of a ship upon the stocks-the heat is applied by means of a nozzle in connection with two elastic tubes, one supplying gas and the other atmospheric air under pressure. M. Lapparent says that specimens of wood of various kinds thus prepared have been placed in a dunghill side by side with unprepared pieces of the same timber, and that at the end of six months decay had attacked the latter in a decided manner, while the former remained perfectly untouched.

This process is particularly recommended in the case of hard woods, which can with difficulty be impregnated with those antiseptic substances which are so effective with timber of the softer kinds. Wood prepared by M. Lapparent's process is being submitted to trial in the Imperial dockyards of France, and also by the railway companies; and it is contemplated to apply it also to carpentry and cabinet-making. We are also informed that similar trials are being made in the English dockyards.

IMPERFECTION OF LIGHTNING CONDUCTORS.- The attention of the French Academy of Sciences has been drawn by M. Perrot to the important question of the inefficiency of the conductors in general use. Three propositions, derived from a number of experiments, are laid down by M. Perrot:-1st, that the surface of the conductor in contact with the water of the soil is generally so insufficient for the rapid dissemination of the electric current, that the conductor cannot be struck with lightning without becoming itself dangerous to the objects in communication with it; 2ndly, that the ordinary conductor is, however, sufficient to give passage to a constant current of electricity sufficient to neutralize that of an approaching storm; and, 3rdly, that in order to arm the common conductor against danger from thunderstorms, the rods should be furnished with a number of long, thin, divergent points of a high-conducting material. The experiments of MM. Pouillet and E. Becquerel have shown that pure water conducts electricity 6,754 millions of times less than copper, and M. Perrot therefore concludes that the surface of water in contact with the conductor should be that number of times at least more extensive than that of the copper. If, therefore, he says, the section of the conductor be equal to one square centimètre, the surface in contact with the water should be equal to 675,400 square mètres, whereas it rarely amounts to more than the tenth of a square mètre. The submerged surface of the conductor is therefore generally about ten thousand times less than it should be, and presents

ten thousand times more resistance to the electric fluid than the other portions of the rod itself, so that when such a conductor is struck it presents a resistance in proportion, and becomes dangerous to surrounding bodies.

The following instructive experiments have been made in support of these deductions :-One end of a rod, representing a lightning-conductor, having been placed at explosive distance from the conductor of an electric machine in communication with a Leyden jar, the other end was plunged into water contained in a metallic vessel in communication with the exterior of the jar and with the earth, the rod itself being isolated in order that one electric current should not neutralize the other without passing through the water. The machine having been set in action, the electricity, instead of traversing the water without flash or noise, presented itself on the surface in the form of a brilliant star, the rays of which stood out from the submerged conductor often to three times the length of the spark of the machine. "In order,” says M. Perrot, "to test the electric tension at various parts of the conductingwire, and consequently the danger to surrounding objects from an ordinary lightning-conductor, I applied a metallic sphere, and found that it was struck at distances varying from a fourth to a third of the length of the spark from the machine."

It is impossible to overlook the practical importance of these experiments and deductions, which demand careful examination by electricians.

THE SARBONNE.-Some few weeks since the learned world was considerably interested, and some of its members rather scandalized, by the fact of a young lady being admitted to academical honours. The other day another curious incident occurred within those ancient walls, where the Admirable Crichton carried off so many laurels in competition with the most brilliant scholars of his day. A young man born deaf and dumb having been received as a bachelor in the literary section, the examination was conducted in writing, the proficiency of the candidate being thoroughly - established. This gentleman is the second son of the Comtesse de Chastellux, daughter of the Duchess de Rantzan, and one of four brothers, three of whom are deaf and dumb.

THE ACADEMY OF SCIENCES has elected Admiral Fitzroy a corresponding member in the section of geography and navigation, in the place of the late Admiral Sir James Clark Ross.

ENGLISH STEAM-ENGINES FOR THE FRENCH NAVY.-A considerable number of eminent engineers and other scientific men, French and English in Paris, were invited a week or two since to see a beautiful working model of a pair of screw engines now being manufactured for the French manof-war Vienne, building at Toulon. These engines were ordered by the Emperor of Messrs. Jack & Co., of Liverpool, and of the same pattern as those supplied by that firm to many mercantile steamers, but not yet, as we believe, introduced into the British Navy. The two great objects in view in Messrs. Jack's arrangement are direct action upon the screw shaft . and economy of fuel. The cylinders are on the Woolf principle of high pressure and expansion combined. The chief peculiarity, however, is the arrangement of the condensers, which are on the principle known as 20


« ПредыдущаяПродолжить »