thousand paces; in breadth it could scarcely exceed a hundred.

It is difficult to conceive how so prodigious a number of these voracious insects can find sufficient nourishment, in so naked a country, till they arrive at maturity; since we must take it for granted that the number of the larvæ greatly exceeds that of the perfect animal. Probably sudden prolific showers, which for a while renew vegetation, may at the same time assist the hatching of the eggs, and the development of the young larvæ; yet this supposition is not a little contradicted by the observation that such swarms are seen at all times of the year, even after a long and general drought, and in countries the most bare of vegetation. On my first journey I once found in the lower Bokkeveld a whole field strewed over with the larvæ of another sort of insect: they sat by hundreds on a bush, gnawing the rind, and the woody fibres; every thing around was devoured, and nothing was to be seen which appeared capable of affording subsistence to these creatures: it was evident that they must have been hatched upon the spot. We may therefore presume that the eggs are hatched very suddenly, and that the young animals require little nourishment; that it is not till they become perfect, at the time when vegetation becomes more abundant, that their extreme voracity commences. The locusts of southern Africa have hitherto been supposed the same as those which infest Asia and some of the southeasterly parts of Europe, gryllus tataricus; but on the examination VOL. LVII.

of some specimens which I preserved, they are determined to be a very different species, and they now bear their appropriate name of Gryllus devastator.

GIRAFFE.

(From the Same.)

The

We had scarcely travelled an hour, when the Hottentots called our attention to some objection a hill not far off on the left hand which seemed to move. head of something appeared almost immediately after, feeding on the other side of the hill; and it was concluded that it must be that of a very large animal: this was confirmed, when, after going scarcely a hundred steps farther, two tall swan-necked giraffes stood almost directly before us. Our transports were indescribable, particularly as the creatures themselves did not perceive us, and therefore gave us full time to examine them, and to prepare for an earnest and serious chace. The one was smaller, and of a paler colour than the other, which Vischer immediately pronounced to be a colt, the child of the larger. Our horses were saddled, and our guns loaded in an instant when the chace commenced. Since all the wild animals of Africa run against the wind, so that we were pretty well assured which way the course of these objects of our ardent wishes would be directed, Vischer, as the most experienced hunter, separated himself from us, and, by a circuit, took the animals in front, that he might stop their 2 K

way while I was to attack them in the rear. I had almost got within shot of them, when they perceived me, and began to fly in the direction we expected. But their flight was so beyond all idea extraordinary, that between laughter, astonishment, and delight, I almost forgot my designs upon the harmless creatures' lives. From the extravagant disproportion between the height of the fore to that of the hinder parts, and of the height to the length of the animal, great obstacles are presented to its moving with any degree of swiftness. When Le Vaillant asserts that he has seen the giraffe trot, he spares me any farther trouble in proving that this animal never presented itself alive before him. How in the world should an animal, so disproportioned in height, before and behind, trot? The giraffe can only gallop, as I can affirm from my own experience, having seen. between forty and fifty at different times, both in their slow and hasty movement, for they only step when they are feeding quietly. But this gallop is so heavy and unwieldy, and seems performed with so much labour, that in a distance of more than a hundred paces, comparing the ground cleared, with the size of the animal, and of the surrounding objects, it might almost be said that a man goes faster on foot. The heaviness of the movement is only compensated by the length of the steps, each one of which clears on a moderate com. putation, from twelve to sixteen feet.

On account of the size and weight of the foreparts the giraffe cannot move forwards through

the power of the muscles alone; he must bend back his long neck, by which the centre of gravity is thrown somewhat more behind, so as to assist his march; then alone it is possible for him to raise his fore-legs from the ground. The neck is, however, thrown back without being itself bent, it remains stiff and erect, and moves in this erect form slowly backwards and forwards with the motion of the legs, almost like the motion of a ship dancing upon the waves, or, according to the phrase used by the sailors, a reeling-ship. It is not difficult to overtake the giraffe with a tolerably good horse, especially if the ground be advantageous, and somewhat on the rise; for it will be easily comprehended that it must be extremely difficult for a creature of such a structure to move upon the ascent.

PITCH WELLS.

(From Dr. Holland's Travels in the Ionian Isles, &c.)

The Pitch wells of Zante are a natural phenomenon, which may be regarded as among the antiquities of the isle; since they were known and described as early as the time of Herodotus, and are mentioned since by Pausanias, Pliny, and other authors. They are situated about ten miles from the city, and near the shore of the bay, on the southern side of the island. We visited this spot, which is called Chieri, a day or two after our arrival in Zante. A small tract of marshy land stretching down to the sea, and surrounded

on other sides by low eminences of limestone or a bituminous shale, is the immediate situation of the springs; they are found in three or four different places of the morass, appearing as small pools; the sides and bottom of which are thickly lined with petroleum, in a viscid state, and by agitation, easily raised in large flakes to the surface. The most remarkable of these pools is one circular in form, about fifty feet in circumference, and a few feet in depth, in which the petroleum has accumulated to a considerable quantity. The water of the spring, which is doubtless the means of conveying the mineral upwards to the surface, forms a small stream from the pool, sensibly impregnated with bituminous matter, which it deposits in parts as it flows through the morass; the other pools are of similar character. The petroleum is collected generally once in the year; and the average quantity obtained from the springs is said to be about a hundred barrels; it is chiefly used for the caulking of vessels, not being found to answer equally well for cordage.

THE SIROCCO.

(From the Same.)

A sudden and violent Sirocco came on from the south-east, carrying our vessel forwards eight or ten miles an hour; but bringing with it, at the same time, all the distressing effects which characterize this extraordinary wind; a sense of general oppression, a dull head-ache, aversion to motion, and lassitude and uneasiness

in the limbs. Those who are strongly susceptible to electrical changes in the air, such as precede and attend a thunder-storm, will easily understand the effects of the Sirocco, as an increased degree of the sensations which they then experience; and, in fact, though I am not aware that the opinion has been held, there are many reasons for believing that the peculiarity of the Sirocco wind is chiefly an electrical one, and not depending either on temperature, an undue proportion of carbonic acid, the presence of minute particles of sand, or any of the causes which have been generally assigned to it. That increased temperature is not the cause, may be inferred from the thermometer being little, if at all, raised by the access of the wind, and from much greater heat often occurring without this singularity of effect. The air of the Sirocco, as it comes from the sea, is not a dry one, but in general thick, and loaded with moisture; much of which appears to be deposited where it passes over any considerable extent of land. I have scarcely, in any instance, observed this wind, in any marked degree, without noticing at the same time, some electrical phenomena in connection with it; to say nothing of the effects upon the body, which, as mere sensations, may perhaps bedoubtfully received in evidence. In the present instance, off the coast of Ithaca, the sky, which had been obscured by the approach of evening, was suddenly kindled, as the wind came on, by broad flashes or gleams of electric light, which seemed to pervade the whole hemisphere, and, at intervals,

the top of the lantern, which was made tight in a pneumatic rim containing a little oil; the upper and lower apertures in the chimney were about of an inch: the lamp, which was fed with oil, gave a steady flame of about an inch high, and half an inch in diameter. When the lantern was slowly moved, the lamp continued to burn, but more feebly; and when it was rapidly moved, it went out. To obviate this circumstance, I surrounded the bottom of the lantern with a perforated rim; and this arrangement perfectly answered the end proposed.

"I had another chimney fitted to this lantern, furnished with a number of safety tin-plate tubes of the sixth of an inch in diameter and two inches long; but they diminished considerably the size of the flame, and rendered it more liable to go out by motion; and the following experiments appear to show, that if the diameter of the upper orifice of the chimney be not very large, it is scarcely possible that any explosion produced by the flame can reach it.

"I threw into the safe-lantern with the common chimney, a mixture of 15 parts of air and one of fire-damp; the flame was immediately greatly enlarged, and the flame of the wick seemed to be lost in the larger flame of the fire. damp. I placed a lighted taper above the orifice of the chimney: it was immediately extinguished, but without the slightest previous increase of its flame, and even the wick instantly lost its fire by being plunged into the chimney. "Iintroduced a lightedtaperinto a close vessel containing 15 parts

of air and one of gas from the distillation of coal, suffered it to burn out in the vessel, and then analysed the gas. After the carbonic acid was separated, it appeared by the test of nitrous gas to contain nearly of its original quantity of oxygen; but detonation with a mixture of equal parts of hydrogen and oxygen proved that it contained no sensible quantity of carburetted hydrogen gas.

"It is evident, then, that when, in the safe-lantern, the air gradually becomes contaminated with fire-damp, this fire-damp will be consumed in the body of the lantern; and that the air passing through the chimney cannot contain any inflammable mixture.

"I made a direct experiment on this point. I gradually threw an explosive mixture of fire-damp and air into the safe-lantern from a bladder furnished with a tube which opened by a large aperture above the flame; the flame became enlarged, and by a rapid jet of gas I produced an explosion in the body of the lantern; there was not even a current of air through the safety tubes at the moment, and the flame did not appear to reach above the lower aperture of the chimney; and the explosion merely threw out from it a gust of foul air.

I

"The second safety-lantern that have had made is upon the same principle as the first, except that instead of tubes, safety canals are used, which consist of close concentric hollow metallic cylinders of different diameters, and placed together so as to form circular canals of the diameter of from

to

of an inch, and an inch and long, by which air is admitted in

much larger quantities than by the small tubes. In this arrangement there is so free a circulation of air, that the chimney likewise may be furnished with safety canals.

"I have had lamps made for this kind of lantern which stand on the outside, and which may be supplied with oil and cotton with out any necessity of opening the lantern; and in this case the chimney is soldered to the top, and the lamp is screwed into the bottom, and the wick rises above the air canals.

"I have likewise had glass lamps with a single wick, and Argand lamps made on the same principle, the chimney being of glass cover ed with a metallic top containing the safety canals, and the air entering close to the flame through the circular canals.

"The third kind of safe lamp, or lantern, and which is by far the most simple, is a close lamp or lantern into which the air is admitted, and from which it passes, through apertures covered with brass wire gauze of of an inch in thickness, the apertures of which should not be more than

of an inch; this stops explosions as well as long tubes or canals, and yet admits of a free draught of air.

Having succeeded in the construction, of safe-lanterns and lamps equally portable with common lanterns and lamps, which afforded sufficient light, and which bore motion perfectly well, I submitted them individually to prac tical tests, by throwing into them explosive atmospheres of firedampandair. By the natural action of the flame drawing air through the air canals, from the explosive

atmosphere, the light was uniformly extinguished; and when an explosive mixture was forcibly pressed into the body of the lamp, the explosion was always stopped by the safety apertures, which may be said figuratively to act as a sort of chemical fire sieves in separating flame from air.

"When the fire-damp isso mixed with the external atmosphere as to render it explosive, the light in the safe-lantern or lamp will be extinguished, and warning will be given to the miners to withdraw from, and to ventilate that part of the mine.

"If it be necessary to be in a part of the mine where the fire-damp. is explosive, for the purpose of clearing the workings, taking away pillars of coal, or other objects, the workmen may be lighted by a fire made of charcoal, which burns without flame, or by the steel-mill, though this does not afford such entire security from danger as the charcoal fire.

"It is probable, that when explosions occur from the sparks from the steel-mill, the mixture of the fire-damp is in the proportion required to consume all the oxygen of the air, for it is only in about this proportion that explosive mixtures can be fired by electrical sparks from a common machine.

"As the wick may be moved without communication between the air in the safe-lantern, or lamp, and the atmosphere, there is no danger in trimming or feeding them; but they should be lighted in a part of the mine where there is no fire-damp, and by a person charged with the care of the lights; and by these inventions, used with such simple precautions, there is