What is a “Pulex Irritans V This formidable name, dear reader, is the scientific cognomen of that formidable little monster, the flea. These minute pests have been made to do, what by nature they are ill calculated for, namely, to administer to the amusement of mankind, showing an amount of docility truly surprising when brought under the subjection of skilled trainers. Novices they are generally adroit enough to elude. The following humorous description of the performances of a troupe of these little comedians we copy from the " Naturalist's Note Book:” “If any inquiring reader wishes to know whether that little tormentor, scientifically known as“ Pulex irritans," and vulgarly as the flea, has ever been found of any use in the economy ot nature's realm, we are happy to inform him that we can answer his question in the affirmative. It must not be imagined that we are going to discuss the question whether it is desirable that the humtan form divine should be subject to sundry little aggravating bites, which are liable to make one's angry passions rise, or whether the ordinary avocations of fleaish life are at all beneflcial to humanity at large. Our object is to place him before our readers as we have seen him, in a new light, earning an honest livelihood {mirabile dictu !) by the sweat of his brow, and afibrding a subsistence to the individual whose philanthropic ingenuity helped him to such a desirable end. " 'From information received' (to use police parlance) we went to an exhibition opened by Mr. Kitchingman, in order to view the performances of his stud of trained fleas, or, as worded in his announcements, ' of trained apterous insects, the only specimens of the articulata in the world ever taught to perform.' These apterous laborers were harnessed by means of an extremely flue hair or flbr of silk, which was tied round their bodies, having the two ends rising perpendicularly above their backs and fastened to a split in a tiny straw, which formed the pole of the carriage they were engaged in drawing. We must confess that at flrst we entered the room with some feelings of alarm, suggested by the thought that some of the menagerie might escape, but this was soon dissipated at the sight of their burdens, which at once set our minds at rest. " The performances were highly interesting and considerably varied. One flea was engaged in a swing, his motion being caused by his kicking violently against one side of a well in which he was placed, which exertion bumped him against the other side and made him indignantly jump away again, so that the unfortunate creature was in a perpetual state of kicking. Another hauled up a little ivory bucket from a well, while a third drew a ship along a tight rope, walking upside down. A fourth was occupied in turning a cardboard cylinder after the manner of a treadmill, but two others, still more unhappy, were occupied in a compulsory see-saw worked by each in turn giving a vigorous spring into the air, thus bringing the other at the opposite end of the balance to the ground. The largest, and consequently, we presume, the laziest, declined to jump at all, but remained sitting quietly down, leaving his comrade miserably suspended from the beam, and frantically clutching at the air in the vain attempt bo reach the ground. A military pulex was engaged in flring 33" a miniature cannon, but on a former occasion the shock was too much for his nervous system, so that when we were present he was unable to perform. The exhibitor kindly gave us a good deal of information about his collection which was very interesting. The flefas are generally imported from Eus-sia and Belgium as being larger and more docile than the English ones, and are set to work immediately, the training beginning with a starvation of two days. At flrst they are very refractory, persisting in progressing by a series of violent jumps instead of a proper jog trot ; but after a week or so they sober down and draw their burdens steadily unless stirred up to violent exertion, when they will gallop vigorously for a few inches, but sit down to rest and regain their breath directly afterwards. After they once learn to walk steadily, we are told, it is difficult to persuade them to leap again. At night all the performers are unharnessed and fed on the back of the employer's hand, after which repast they repose in a box enveloped in cotton wool. If at night any performer does not feed heartily, and with a good appetite, his progress is proportionately languid and slow the next day; but when any member of the establishment declines to eat for three or four days, his end is expected in a short time. About a hundred others are usually kept in stock and training, as they are comparatively short lived, three or four months being supposed to be the allotted period of their days. Perhaps conflnement and hard labor afiect their spirits. The workman engaged in drawing up the bucket had, however, reached the hoary age of nine months, and his demise therefore will not be unexpected. The immense muscular power possessed by these creatures is here fully demonstrated. No doubt many of our readers have experienced the diflSculty of holding a wild pulex for a minute or two, before consigning it to perdition. The flea Hercules draws a model of a ship estimated to be flve hundred times his own weight in a very easy manner. It seems that the English fleas are the most stubborn and difiicult to train, but when once properly subdued they work better and last longer than the others ; but the Englishman we saw was anything but steady, tugging and straining at his collar in a frantic manner. "One of the most interesting features of the exhibition is the beautiful form of the models employed for the work. They are carved in ivory and exquisitely flnished, and, of course, of the minutest size possible, being adapted to the fleas in a most ingenious manner, and manufactured hy the exhibitor himself. The delicacy of touch and sight attainable after practice is surprising, as each performer is harnessed without the aid of a glass, merely being taken between the operator's flnger and thumb. Mr. Kitchingman told us also that he knows every individual performer by sight, so that he has no difficulty in selecting each member of his troupe for his own work." Revival of Interest in Sorgl&um. The quantity of cane planted this year, says the Strfgo Journal, and the interest manifested in sorghum, is greater than in any year since 1866. The value of sorghum as a farm crop is beginning to be appreciated, and those now engaged in the business are devoting more attention to its cultivation, and are providing better facilities for its manufacture than ever before. This is wise, and all the enterprise which may be devoted to the crop will be well rewarded. Sweets of all kinds are and must be high for the present, and proba bly for many years. Last year's crop of sorghum is about exhausted. New Orleans and tropical molasses are scarce, and sugars are almost at famine prices. This state of things is, of course, aggravated by the disturbances in Cuba, and by the fact that Louisiana has not produced all the sugar and molasses that could be consumed, as many predicted she would. But there is an underlying cause ol high prices greater in importance and greater in permanence than these accidents of the time, and which would be felt even it peace prevailed in Cuba, and a half million hogsheads of sugar were being made in Louisiana. We refer to the natural increase in the consumption of sugar, and to the growing disproportion between the demand and the supply. This will prevent sugar and molasses from declining to the old prices, until some new and much more productive source of sugar shall be developed. We make this remark to remove a notion which prevails, that, if Cuba were restored to peace, and Louisiana to her former productive capacity, sugar and molasses would be furnished at their old prices, and then sorghum would be no longer profltable. Eeasoning thus, many have refrained from engaging in sorghum, and many who are in the business, regarding it as a temporary or short-lived enterprise, fail to make adequate and permanent preparation for the business. This is a mistaken policy, we think, and we advise those who are making preparation for work to consider well, and see if they are not warranted in regarding sorghum as a business likely to be permanently profltable, and worthy of a permanent and a substantial outflt in buildings and apparatus. But all tiie probabilities are that Cuba will not for many years, if ever again, produce her former supply of sugar, and that Louisiana will not for five, and, perhaps, ten years, produce as much sugar as she did before the war. So that the producer of sorghum, may calculate upon a good substantial and a continuous profit from the business, and also upon the chances amounting almost to a certainty that the profits will be for some years, at least, extraordinary. Under these circumstances the " revival of interest in sorghum," must, we think, become a permanent and a growing revival. In a recently published paper on the gases given oflf by fruit it is stated that various kinds of fruit after having been plucked from the trees—for instance, apples, cherries, goose-bermes,and currants—begin to absorb oxygen and give ofl*car- bonic acid. 180 Casting Metals, Olass etc. Letters patent have been taken out in France for improvements in casting metals,glass, and other materials. We give an illiistrated description of the apparatus employed. An airtight vessel is fornied of a kollow cylindrical vessel of cast iroB, closed at its lower end, and strengthened on the exterior by rings of wrought iron shrunk upon it. The vessel is closed air-tight at its upper end by a hemispherical cover, between which and a flange around the upper edge of the vessel is placed a washer of goft metal; the lid when closed is pressed firmly down upon the washer by a screw working through a head or nut which is held down to the vessel by three descending arms, formed at their lower ends with lugs to hook on to other lugs which pass below the flange on the top of the vessel. When the head or nut is thus held the lid can be forced down by turning the screw which works through the nut. In case where it is desirable to apply the heat to the material during the time it is solidifying, as, for example, when casting ingots of steel, the mold into which the steel is to be cast is surrounded with a casting of thin metal, and placed within the air-tight vessel. Between the thin m )tal case and the sides of the vessel, pieces of charcoal are roughly broken up, and are so placed that air may penetrate readily through the charcoal; when the melted metal is poured into the mold the charcoal is thereby brought to a red heat and ignited, and by this means the metal is kept heated. As soon as the metal has been poured into the mold, a thin plate is placed upon the top of the metal in fusion, and a thick plate of fire-clay is placed over the top of the mold; the lid of the outer vessel is then put on, and the joint is made air tight by forcing it down by a screw,as above described. Compressed air is afterwards admitted into the vessel from a suitable reservoir; the communication between the reservoir and vessel can then be closed by a cock, so that the pressure in the vessel may be increased by the expan sion of the air as it becomes heated. Fig. 1 of our illustration shows a vertical section of an apparatus constructed as described, the apparatus is more especially suitable for making castings of steel, but similar means may be employed when making castings of glass or otherfluid substances. A is a strong vessel of cast iron, strenghtened exteriorly with wrought-iron rings, a, shrunk upon it; B, a lid for closing the vessel air tight; S, the screw for pressing down the lid or cover on top of the vessel, A; the screw works through the nut, n, which, when the lid is to be closed, is held down to the vessel. A, by three arms formed at their lower ends with lugs, c, which are passed under other lugs, o, the stems, P, of which are fixed to the upper strengthening ring, a, of the vessel, A. The screw and nut are connected to the top of the lid, B, by three other arms nl, descending from a ring, n2, through which the screw passes freely. The construction of these parts is clearly seen in the cross section shown at Fig. 2. At th top of the screw is carried a pulley, over which is passed a cord, E, by which the screw and with it the lid, B, can be raised or lowered when the lid is disconnected from the vessel, q, q are steady pins to keep the lid concentric with the top of the vessel. A, and m, is a soft-metal washer for making the joint between the vessel, A, and lid, B, air tight. In the interior of the vessel. A, is placed an iron ingot mold, L, into whih the melted metal is to be pored ; the lower end of the mold is closed by an iron bottom, as shown, and the top of the mold is covered over with a slab of fire tile, marked D, the in-gcft mold is surrounded by a casing, T, of thin sheet iron, and between this casing and the sides of the vessel. A, is placed charcoal broken into small pieces so that the air may pass freely amongst it. At Fig. 3 is represented a reservoir of compressed air communicating with the vessel. A, by a pipe, r, on to which is fitted a pressure gage, F, to indicate the pressure of air in the reservoir. The passage of air through the pipe, r, from the reservoir to the vessel. A, is controlled by a cock, R, the pipe, r, also carries a tap, Rl, by opening which the pressure of air may be reduced when desired. The apparatus is used in the following manner: Supposing the air reservoir to be filled with air at a pressure of about 10 atmospheres and that the melted steel is ready to be run into the ingot mold, the metal is poured into the ingot mold, L, the small disk of sheet metal, Dl is placed on the top of the fluid metal, and the whole is covered over with the disk of fire tile, D, as shown in the illustration, the fire tile having been previously heated to a white heat. As the ingot mold becomes heated by the metal poured into it the heat is radiated from it across the small air space between the mold and the thin metal case by which it is surrounded, heats this casing to a red heat, and ignites the charcoal by which it is surrounded. The lid, B, is closed and fixed securely on the top of the apparatus, the lower end of the 3crew being forced down on the circular washer, u, on the top of the lid, B, by turning the screw of the lever arms, Tl, upon it; the apparatus being closed, the tap, R, is opened, the compressed air passes into the apparatus, so making the pressure in the vessel, A, equal to the pressure in the air reservoir, the lir becoming quickly heated, in the vessel. A, the pressure pises, and if the tap, R, is then closed, the pressure in the vessel, A, will rise above that in the air reservoir. It will thus be seen that the pressure in the vessel. A, ci-n readily be regulated by means of the taps in the pipe, r. We must here remark that the quaitity of air which passes from the air reservoir into the vessel. A, is relatively very small, as the vessel. A, is almost entirely filled with the ingot mold, the casing, and the charcoal with which it is surrounded. Thi is very advantageous for economizing the compressed air employed, but more especially for concentrating the heat in a small space, so that the metal in the ingot mold may cool slowly and as regularly as posible, the exterior of the vessel, A, is surrounded by water contained in a bath or vessel, Y, so as to keep it cool, as shown by our illustration. Steel thus cast into molds and subjected to pressure, is under the most fa'rable conditions for solidifying into a homogeneous mass, for as regards pressure it is compressed with a force which is considerable, as a pressure of ten atmospheres corresponds to a column of melted metal of about forty-five feet high ; if this is compared with the hight of the head or get of metal usually employed by founders it will be seen how greatly superior is the process of casting above described to that usually employed. A pressure of ten atmospheres has been taken as an example, but there is nothing to prevent a pressure of twenty thirty or forty atmospheres being employed, as this may be done without danger. By the process above described a dense and homogeneous ingot is obtained, as the metal is not only subject to pressure while in a fluid state, but also as it passes through the pasty into the solid state. By the combined use of a concentrated heat and great pressure a highly malleable steel is obtained, and also a steel which when tempered becomes extremely hard, these being the two most valuable qualities in steel. Improvement in Pipe Tongs, This is an implement which is of great importance in gas fitting and plumbing, and presents decided advantages over the old style of pipe tongs. By its use the pipe may be more firmly grasped with less liability to injury, while it is equally convenient in use. fei the engraving. A, is a curved jaw comprising' about, or a little less than three fourths of a circle, j and is forged with the handle, B, in one continuous piece. C is also a curved jaw about, or a little less than one fourth of a circle in extent, and is riveted to a bent plate, D, passing over the back of B. The other handle, E, is pivoted to D, and the two handles are connected by a link, F, so that when the handle E, is opened to the position shown by the dotted outline, the jaw, C, is withdrawn to the position shown by its dotted outline. This allows the pipe to enter between the jaws. When the handles are pressed together, the jaw, C, approaches the other with great force through the action of the toggle formed by the handle, E, and the link, F ; but as the pipe is grasped on all sides there is no danger of crushing it. The jaws are toothed internally in the usual manner, and for the same purpose. Patented, through the Scientific American Patent Agency, Aug. 3,1869, by R. Grain of Shaffer Farm Dennison Post Oflace, Pa., who may be addressed.