It is common to meet with patients who cannot speak three words without exciting a fit of coughing, and who, notwithstanding, cannot be persuaded that speaking retards their recovery. In like manner, in spitting of blood, and in the early stage of tubercular consumption, when the breathing cannot be excited without direct mischief, it is often difficult to convince the patient of the necessity of silence. He perhaps does not feel pain on attempting to speak, and says that "it merely raises a short tickling cough, which is nothing." But if he persists, dearly-bought experience will teach him his error.

All violent exercise ought, for similar reasons, to be refrained from, during, at least, the active stages of cold. Everything which hurries the breathing, whether walking fast, ascending an acclivity,or reading aloud, has the same effect on the diseased lungs that motion of the bone has on an inflamed joint. Many persons hurt themselves much more by the active exercise they take during a severe cold, than by the mere exposure to the weather. A person, when suffering from cold, may go out for a short time, even in an open carriage, more safely than on foot.

After all active disease has been subdued, or when nothing but delicacy remains, the adequate exercise of the lungs is one of the best means of promoting effectual recovery. Those parents, therefore, act most erroneously, who, in their apprehensive anxiety for the protection of their delicate children, scrupulously prohibit them from every kind of exercise which requires the least effort, and shut them up from the open air during Winter, with the false hope of thereby warding off colds, and protecting their lungs. The greatest delicacy of constitution has been thus engendered, especially when an undue quantity of warm clothing was employed.

[COMBE'S Physiology applied to Health.]

The morn has but just looked out, and smiled,
When he starts from his humble, grassy nest,
And is up and away, with the dew on his breast,
And a hymn in his heart, to yon pure, bright sphere,

'To warble it out in his Maker's ear.

Ever, my child, be thy morn's first lays

Tuned, like the lark's, to thy Maker's praise.

What is that, mother?—

The dove, my son.—
And that low, sweet voice, like a widow's moan,
Is flowing out from her gentle breast,
Constant and pure by that lonely nest,
As the wave is poured from some crystal urn,
For her distant dear one's quick return.
Ever, my son, be thou like the dove,-
In friendship as faithful, as constant in love.
What is that, mother?—

The eagle, boy,
Proudly careering his course of joy,
Firm in his own mountain vigour relying,
Breasting the dark storm, the red bolt defying;
His wing on the wind, and his eye on the sun,
He swerves not a hair, but bears onward, right on.
Boy, may the eagle's flight ever be thine,
Onward and upward, true to the line.

THE USEFUL ARTS. No. XIV. THE ANIMALS, AND ANIMAL PRODUCTS EMPLOYED AS FOOD BY MAN. GENERAL ENUMERATION OF ANIMALS.-COOKING. THE OX KIND, THE SHEEP-SALT. THE number of species of animals which man consumes for food are hardly less numerous than those of the vegetables. Of the nineteen classes into which the former natural kingdom is divided, eight or nine contribute to the regular sustenance of the most refined and civilized nations; and some species of all classes are either habitually eaten by savage tribes of different countries, or, at least, are occasionally had recourse to under peculiar circumstances; as, for instance, during a scarcity. The digestive powers of the human stomach are nearly unlimited, and it is commonly deficiency in quantity rather than the quality of the animal substance, that causes disease or mortality. We shall here, however, only enumerate the animals which are ordinarily consumed by the cultivated nations of Europe and America, and shall arrange them according to the classification of the naturalist.

Of the class MAMMALIA, the most important order to man, in this point of view, is, and from the earliest ages has been, that of the Ruminating Animals, comprising the Ox, the Sheep, the Goat, and Deer of all kinds.

The Hog and its congeners, belonging to the order Pachydermata (thick skinned), rank next. The Bear is the only genus of carnivorous animals which furnishes a species eaten by Europeans. That species, the Brown Bear of Russia and Northern Europe, is an ticular parts which are on some occasions eaten. In China, herbivorous quadruped,-and of this animal, it is only parindeed, the poor do habitually eat Dogs; and even Cats and Wolves are said to be eaten in some parts of Europe; but these are cases of scarcity of food in proportion to population, which we have already excepted from our view of the subject.

Hares and Rabbits belong to the order Rodentia (Gnawers), as do also the Marmot, Cavi, Guinea-pig, Kangaroo, Jerboa, &c. &c., which are occasionally consumed by our colonists in different quarters of the globe.

The number of genera of BIRDS, of which species are eaten, is very great. The order Gallinæ, corresponds to the Ruminantia in importance, since it embraces the Domestic Fowl, the Turkey, Guinea-Hen, Pheasant, Partridge, BlackCock, Peacock, Grouse, &c. Next ranks that of Palmipedes (Web-footed), containing the Swan, Goose, Duck, Widgeon, Teal, &c. &c. Snipes, Woodcocks, &c., belong to the order Gralla. These are all that need be mentioned.

Of REPTILES, the Turtle is interesting to two very opposite sorts of persons: namely, seamen, to whom it a luxury in the absence of other fresh meat, and epicures, to whom it is always a luxury. With these exceptions, this class furnishes no food to civilized nations.

It is far otherwise with FISH: the number of species which contribute to our diet is greater than that of any other class, and vary as much in magnitude, as in form and habits. From the Sturgeon to the White-bait-from the Plaice and Halibut to the Eel, the ocean, rivers, lakes, and rivulets, are ransacked for this invaluable and inexhaustible kind of food.

The Oyster, Cockle, Muscle, Whelk, and a few others, are all the MOLLUSCOUS animals that fall under our notice; Crabs, Lobsters, Crawfish, Crayfish, Shrimps, Prawns, &c., are furnished by the class TESTACEA, and conclude our catalogue.

The flesh of animals is greatly influenced by their mode of life, the quantity of exercise which they take, and even by the mode in which they are killed to serve us for food. The flesh of wild animals is in a healthier state, more abundant in the various nutritive principles, and these are more equally distributed, than that of domesticated animals; but, at the same time, the former is tougher, or more fibrous and sinewy. These qualities are somewhat modified by violent exercise just before death; and hence it is a fact, that when game is hunted, the quality of the meat is improved. Hence, too, the reason why wild birds are more flavoured, and in every respect better, than fowls kept in yards or coops.

Fish, as has been stated, is an excellent food, provided there is enough of it; but shell-fish, of all kinds, are not to be included in this commendation. Generally they are indigestible and not nutritious.

One of the effects of all food, especially animal food, is to

THE extensive adoption of SUSPENSION BRIDGES is far from the least important mechanical improvement which nas distinguished the present eventful century; an account of the principles on which these bridges are constructed, cannot, therefore, but be interesting to our readers.

If a fallen tree, lying across a stream, served as a model for the earliest bridge, the slender stem of a creeping plant, swinging from bank to bank, may have suggested the possibility of suspending a rope-bridge across a river too wide to be spanned by timber beams in one length, when the rapidity of the current, or other circumstances, precluded the erection of intermediate piers.

So obvious, indeed, is the principle, and so easy the construction, of such hanging bridges, that they have apparently been adopted in every country where the people had materials, and possessed sufficient ingenuity to manufacture flexible ropes from vegetable fibres, or from hides. They were found to have been in use from time immemorial in South America, when that country was first visited by Europeans; and such a bridge, called a Tarabita, is to this day employed to cross the valleys and torrents of the Cordilleras.

A cable, made of strips of hide, or fibres of plants, is stretched across, from a post or tree on one side, to a wheel on the other; this wheel, or some other contrivance, being necessary to strain the rope tighter when it gets too slack. A basket, large enough for a man to sit in, is suspended by loops from the cable, and the traveller is pulled across by a smaller rope led to the shore. Frequently two such cables are set up, each sloping from one bank to the other, to facilitate the passage of the basket.

The bridge described by Baron Humboldt, as thrown over the river Chambo, in Quito, is of a better construction than the Tarabita. The main ropes, which are four inches in diameter, and made of fibres of the Agave Americana*, are laid over rude timber frames on each bank, and secured behind them by being fastened to posts driven into the ground. The road-way is laid on these ropes, and consequently partakes of their curvature, thus materially increasing the difficulty of walking on it; but the traveller can walk over it, and there are side parapets to keep him from falling over. The bridge is named Penipe, and is 131 feet in span.

Captain Hall describes a bridge over the Maypo, in Chili, the main ropes of which are six in number, three on each side the road-way: they are firmly secured to the rock on the highest bank of the river, and are carried over a timber frame on the other, which is lower, down to the ground, where they are fastened to trees, and to stout posts driven into the earth. Short vertical cords are suspended from the main ropes, to carry the horizontal ones, on which the transverse planking of the road-way is laid. The span is 123 feet; and the ropes being of hide, their elasticity causes such an undulation, that travellers usually dismount and drive their mules over before them.

The following adventure, which occurred at this bridge on the occasion of the passage of a body of troops, is narrated in the Memoirs of General Miller. The infantry passed without the smallest difficulty, as did also the cavalry, each man leading his horse, and going a few at a time. When the artillery came up, doubts were entertained as to the possibility of getting it over. Captain Miller, at length, volunteered to conduct the first gun: the limber was taken off, and drag-ropes attached to the carriage, by which the piece was to be restrained from descending the curved road-way too rapidly, while the trail was held up by two gunners; but, notwithstanding these precautions, the bridge swung so much from side to side, that the men lost their balance, and the gun was overturned; the carriage, by becoming entangled in the side parapet of thongs, saved it

This is the American Aloe, which is remarkable for the long period which elapses before it flowers. The fibres of this plant are very tough, and well adapted for making ropes of, for which purpose it is extensively employed in America. The French term thread of these fibres, fil de pite. It may be mentioned here, that hemp is never the material of which the ropes are made, employed in the bridges of America or Asia, described in the text. The other vegetable products used for the purpose are coir, or the fibres of the cocoa-nut, the stems of the +Extracts from a Journal written on the coast of Chili, &c., in 1820, 21, and 22,

bamboo and other reeds, &c.

from falling into the river, but caused the road-way to tilt over so much, that every one on it was obliged to cling to whatever he could catch hold of, to save himself from dropping off into the foaming torrent sixty feet beneath. None dared, for some time, to venture to the relief of the party, expecting the bridge would break down every instant, especially if loaded with any additional weight: when, however, it was seen that nothing material gave way, two or three men crept along it to render assistance. The gun was with difficulty dismounted; the carriage taken to pieces, and so conveyed to the banks. Every one was saved, but the artillery was obliged to be sent four or five leagues round, to a ford lower down the river.

So well adapted is this form of bridge for crossing the mountain torrents and defiles of the Cordilleras, that, in recent times, one of great length has been constructed over the Santa, after a fruitless endeavour to build an arched bridge, at an expense of £40,000.

In all the mountainous districts of India and Central Asia, suspension-bridges, of ropes, or chains, have been in existence from the earliest ages. Mr. Frazer, during his tour through the snowy range of the Himmala mountains, saw, and has described, several. Many consisted, like the Tarabita, of a single rope stretched over posts on the banks; a kind of wooden saddle is made to slide on the ropes, over which loops are hung for the passenger to seat himself in, and he is hauled across by a line attached to the saddle. Such a bridge is called, in that country, a l'hoola. Mr. Frazer was one of a large party which crossed the Touse by a rope-bridge of this kind. All got over safely, with the exception of a Ghoorka sepoy, who, having his wife among the troop, wished to take her across with him, lest she should be frightened in making the formidable passage alone. When they had got about half way over, the tow-rope broke: the man, anxious to rescue his wife as quickly as possible from her awkward situation, let himself down, intending to fall into the water and swim across with the portion of rope that remained attached to the saddle, pulling the woman after him. He unfortunately got entangled either in the cord, or in his dress, and was carried away by the current, and perished; thus falling a sacrifice to his conjugal affection.

Captain Turner, who was sent on a mission into Bootan and Thibet in 1783, crossed a defile in the mountains, near the river Tchin-tchieu, by a formidable bridge of this kind. It consisted of two ropes, made of the twisted stems of creeping plants, stretched across the chasm, parallel to and near each other; they were encircled by a hoop, in which the traveller sat himself, and holding one of the ropes in each hand, worked himself across. Nothing but the alternative of having to pursue a circuitous road of many miles, could induce a person unaccustomed to such bridges to cross by such means.

Near to this was another of a superior construction, over the above-named river itself, and called Chuka-chazum from its proximity to the castle or fort of Chuka. The river runs between precipitous rugged banks, of unequal height and declivity, in the steepest of which is a solid pyramidal pier of masonry, having an opening through the top for the road-way; in this opening, a strong double frame, like a door-way, is fixed. On the other side of the river, at a little distance from the bank, there is, on the corresponding pier, a square building, containing a chamber which serves as a sort of ante-room to the bridge. From the front of this building a covered gallery of timber projects to the edge of the river, a distance of about thirty-five feet.

There are five main chains of iron, to form the floor of the bridge, secured to the front wall of the building, and, after passing over the lower beams of the gallery, they are attached to the bottom of the frame in the opposite pier: another chain on each side of the bridge is fixed, nine feet above the former, to the top beam of this frame; and, being carried through the wall of the chamber, pass down to the ground, where they are secured, but in what manner does not appear. From these two upper chains hang vertical suspending rods to the outer ones of the floor chains, which they thus assist to support, while they form a parapet to the bridge; the roadway is covered with strips of bamboo. This structure is so ancient, that it has a fabulous origin assigned to it by the people of the country,

At about a day's journey from Chuka, the same traveller saw another suspension-bridge over the river, which approached in its principle of construction those erected in Europe at the present day. Two chains, four feet apart, were stretched across, carried over a pile of stones raised on each bank, and after descending through a sloping passage cut in the rock, they were fastened to a large stone at the bottom, which was kept down in its place by a mass of rock and stones heaped on it. A single plank, for a footway, was suspended four feet below the chains, by means of roots and creeping stems attached to them on either side. The bridge was seventy feet long, and was called Selo-chazum.

It is a remarkable fact, that now, when the advantages of suspension-bridges have caused their general adoption in the present century, (as we shall presently mention,) the English in India, when they have occasion to erect such a bridge in any part of their extensive possessions, adopt ropes of coir, split bamboos, and all those materials which were employed for the purpose, perhaps, 2000 years ago.

The first of these modern Indian bridges was erected in Calcutta, by C. Shakspeare, Esq.; the span being 125 feet, and the width 64; the platform being made of bamboos laid on coir-ropes, suspended from others, as in those above described. And many others of similar construction have been since established.

It does not appear that this fragile and perishable kind of bridge was extensively introduced into Europe, for several reasons; the chief of which, perhaps, was the early discovery of the arch, which admitted of the erection of more substantial structures; and it was not till the latter end of the last century, that the advantages of suspension-bridges attracted the attention of scientific men in that quarter of the globe, from the following considerations.

During the existence of the Roman empire, and the ages which succeeded its overthrow, commercial intercourse between the various states of Europe met with but little encouragement; hence, the construction of permanent bridges was only undertaken from absolute necessity, in the largest cities, and on the principal roads; while the impediment they caused to the navigation of the rivers was entirely disregarded, as being but little felt.

But when the rapid extension of trade, especially in our own country, required not only the erection everywhere of new bridges, but that the convenience of inland navigation should be consulted, the adoption of arches of considerable span, besides lessening the expense of such structures, also satisfied the last-mentioned claims. At length, engineers, having nearly attained the limits of construction of arches, turned their attention to suspension-bridges, both as considerably cheaper than those of stone, and admitting of application where the latter were impracticable.

It appears, from the accounts above given of Peruvian and Indian bridges, that, even with such light structures, more than one rope on each side was considered essential to security; not only that, if one gave way, the others might sustain the road for a time, till the injury could be repaired, but because several small ropes are proportionably stronger than one large one.

The same precautions were still more necessary with such suspension-bridges as were now contemplated, in which iron must be adopted as the sole material. The enormous weight of iron chains, independently of that of the road-way they uphold, not only requires an increase in their number, but that every precaution should be taken to render them equally strong in every part.

This latter condition is best fulfilled by making each link consist of several parts united together, because it is much easier to make a small bar sound than a large one, and if There are, however, several ancient bridges on this principle in various parts of Europe, as, for example, over the Arratis, at Stoffingen, in Switzertand, and several between Trente and Inspruch; the chains of which are long pieces of wood, put together with iron pins. There are also two or three in Franconia and other parts of Germany, all

situated in mountainous countries, where recourse would be had to this kind of structure, for the reasons stated in the text. But, as all these bear but a small proportion to the bridges of the ordinary form in the same countries, we are borne out in stating them not to have been formerly ever common in Europe.

Suspension-bridges of rope have frequently been used in military operations, to facilitate the passage of troops and artillery; but these were only temporary structures, analogous to the pontoon bridges, &c., generally used in warfare. The French, in their retreat, having broken down an arch of the fine old Roman bridge at Alcantara, over the Tagus, a platform, carried on cables, was laid across the aperture, to enable our army to pass, in the early part of the campaign on the Peninsula. For a description and view of this bridge, see Sir Howard Douglas, On Military Bridges.

It is this last-mentioned quality that induces the employment of iron wire to form the chains of; each link consisting of numerous coils of such wire bound togethert. It has been found, by calculation and experiment, that there is a certain degree of curvature in a flexible chain or rope, when employed in a suspension-bridge, which is most conducive to stability; and since the lowest point of that curve, or the level of the road, must be elevated sufficiently above the river, or valley beneath; in order that the chains may assume that curvature, they must be suspended from a pier, or tower, of some kind, erected at each end of the bridge.

But it is obvious that no such upright structure could be capable of resisting the tension of the chains, even of a small bridge, if they were simply fastened to its summit. It is necessary, therefore, after carrying the chains over these piers, to bring them down again to the ground, and to fasten them either to some natural rock, or to an artificial mass of masonry, which, by its size and weight, may prevent the chains from subsiding in the middle of the span.

In order to avoid any lateral pressure that would tend to overthrow the piers, either way, it is requisite that the weight of the suspended mass should press perpendicularly on them. This is effected by causing the chains to descend from the piers, each way, at an equal angle: but this precaution is commonly sacrificed to other considerations, and the stability of the piers secured by additional size or strength, and by their pyramidal form.

And since every variation in temperature must occasion a change in the length of such a mass of iron, which will cause some play of the chains on the summits of the piers, an effect which would be also produced, though in a slighter degree, by any temporary vibration, the chains, instead of resting directly on the piers, are laid on friction rollers, which allow of that motion without its shaking or deranging the structures.

SUSPENSION-BRIDGES IN MODERN TIMES.

A CHAIN bridge was erected across the Tees, near Middle ton, in Yorkshire, about the year 1741. This is said to have been but a rude work, little superior to the bridges we have above described. It was not till the year 1796, that any suspension-bridge of consequence was erected in modern times. This was accomplished by Mr. Finlay, over Jacob's Creek, near Greenburgh, in North America, and many others, either under his immediate direction, or according to his plan, were speedily constructed in various parts of the United States.

One of these, over the Merrimack, near Newbury Port, is a work of considerable size and strength: it is 244 feet long in one span; there are ten chains, three on each side, and four in the middle, forming two road ways, each 15 feet broad; the chains pass over suspension pillars, 35 feet high, down to the ground, into deep wells, in which they are secured to heavy stones. This bridge is used for carriages, and cost about £5500.

In 1814, a plan was proposed for making a direct road from Runcorn over the Mersey to Liverpool, to include a bridge across Runcorn Gap, in lieu of the present ferry there. As it was necessary, on account of the navigation, that any such bridge should consist of three arches, or spans only, the centre one of which must be 1000 feet broad, and at least 70 feet high, a bridge of arches was out of the question, and the late Mr Telford proposed a suspension one. This was the first occasion on which English engineers directed their attention to the subject; and several small suspension-bridges, chiefly of iron wire, were, in consequence, erected in Britain, before the year 1820.

The first of these was thrown across the Gala-Water at Galashiels, in 1816: it was made of slender wire, with a span of 111 feet, and cost about 40%.§

The superior tenacity acquired by drawing is such, that iron wire will support at the rate of 38 tons per square inch of its sectional area; while good wrought iron bars will only sustain 27 tons before they break.

If this curvature were diminished by drawing the chains too tight, their own weight would rapidly increase the rate of tension, and thus weaken their power of supporting the road. Every one knows that it is impossible to stretch a cord or chain, of any length, quite straight in a horizontal line; long before it becomes so, it will break. § What would it have cost to erect a timber or brick arch, to answer the purpose? Certainly not less than thrice as much.