serve their purpose very well; although, perhaps, others a little better might have been chosen. We can use them independently of any views we may hold on the single, double, or no-fluid theories of electricity. As electricity is but a condition of matter, we can scarcely hope to get beyond the bounds of assumption. It is simply a theory, and not an established law or principle, to say that there are one, or two, or any number of electric fluids: what evidence there is is decidedly the other way -that is to say, electricity is a force which is not a fluid, nor does it in many cases behave like a fluid. As, however, we have set ourselves against theorising, let us simply re-assert that there are two electric states or conditions, and let us endeavour to identify them.

Ex. XCI.-Attach the thread or ribbon connected to the paper loop (Fig. 39), or the wire stirrup (Fig. 41), to

B

instead of attraction we shall get repulsion, for the suspended rod will recede from that held in the hand. Lay the second stick on one side in a dry place, and electrify the hot dry glass tube (Ex. LXXIX.). Then bring it near A, attraction takes place, and if the glass be brought near B we get even stronger attraction (instead of repulsion, as with the sealing-wax). Now substitute for the suspended sealing-wax a piece of dry warm glass tubing, say half-an-inch in diameter, and ten or twelve inches long (with-if you have it--one end sealed). The electrified sealing-wax or glass held in the hand will attract either end A or B of the unelectrified glass. But if the end B of the glass be electrified in the usual manner, strong attraction will be exerted between it and the sealing-wax, while it will recede from or be repelled by the electrified glass.

Here, then, we see that electrified sealing-wax attracts electrified glass but repels electrified sealing-wax, and conversely electrified glass attracts electrified sealing-wax and repels electrified glass: clear evidence that there are two electric states, that the states produced on similar bodies by similar rubbers are mutually repellant, while the states produced on dissimilar bodies by dissimilar rubbers produce (although not always necessarily) attraction.

Ex. XCII. That either electric state is self-repellant may be further demonstrated by a modification of Ex. LXXXV. Draw a piece of narrow silk ribbon between two adjacent fingers provided with india-rubber stalls, and then carefully suspend the ribbon over one of the fingers held out straight, the two halves of the ribbon, being similarly electrified, will repel one another, and take up positions as shown in Fig. 48. The stronger the electrification the greater, of course, will be the divergence of the ribbon.

a support of some kind, such as that illustrated in Fig. 36 (page 495). Fig. 47 shows the arrangement. Any other form of support, however, that suggests itself to the young electrician will do for this purpose, as insulation is not essential. We know (from Ex. LXXIV.) that if an unelectrified stick of sealing-wax, &c., be placed on the stirrup, the approach of an electrified rod results in attraction. Similarly (Ex. LXXIX.) the unelectrified sealing-wax is attracted by an electrified glass tube. So also would the electrified sealing-wax or glass attract an unelectrified glass tube placed in the stirrup. Let, now, the end B of a stick of sealing-wax, say seven or eight inches long, be rubbed with a piece of warm, dry flannel, and placed on the stirrup. Then bring near the end A, another electrified stick of sealing-wax, attraction will ensue; but bring the second stick near the end B, and

Fig. 48.

Fig. 49.

Ex. XCIII.-Another interesting experiment may be performed with the sheet of electrified note-paper (Ex. LXXXIII). Having electrified it by rubbing it while laying on a hot, dry board with a piece of india-rubber, cut it into a kind of fringe, but drawing a sharp knife through it several times, making the cuts parallel, and letting them extend nearly the length of the paper. Half an inch, or thereabouts, may be left uncut, that is, sufficient to hold the strips together. Now raise the paper carefully from the board, and fold up what we may call the top of it so as to leave the strips free and hanging downwards. It will be observed that the strips will exhibit decided evidence of being similarly electrified by the energy with which they mutually repel one another, taking up the positions indicated in Fig. 49.

Ex. XCIV.-A very attractive experiment is that illus

trated in Fig. 50. A stand consisting of a stick of wood, 18 in. or 20 in. long, stuck into a suitable piece of flat wood, say 7 in. or 8 in. in diameter, is provided. with a funnel support. This may be arranged in a

Fig. 50.

variety of more or less simple ways. The simplest, perhaps, is a piece of stout wire, bent approximately into a circular loop, and twisted securely round the upper portion of the wooden rod. If the rod is round, a more elegant contrivance may be easily constructed by procuring a piece of brass tubing about 2 in. long, having an internal diameter slightly less than the thickness of the rod. Slit this tube along one side and solder on to it, near the top or bottom, a piece of stout wire bent to shape, or a piece of sheet tinned iron with two holes cut in it, one to carry the funnel, the other to slide over the rod. The brass tube, if of the proper diameter, will fit spring-tight on to the rod, and so enable it to be placed at any height. If it is desired to secure the tube by means of an ordinary screw, or, better still, of a thumb or milled-head screw, then a stout piece of tubing will be required, or a solid piece of metal may be soldered to the tubing, and have a hole drilled through it and tapped for the screw. When a square rod is employed, and it is not thought necessary to provide means for altering the height of the looped arm or carrier, a suitably-shaped piece of tinned iron may be employed, cutting a hole in one end of it for the funnel, and bending the other end at right angles, the bent portion being securely tacked on to the wooden upright. A number of other ways for accomplishing this will doubtless suggest themselves. In the loop or hole place a small glass-funnel, F (procurable at a chemical apparatus maker's), provided with an aperture of about in. in diameter; partly fill it with fine silver sand, and the sand will fall through in a straight column like that indicated on the left side of the support. If, however, one end of a wire, W, be immersed in the sand, while the other end is connected with a glass tube or other body being electrified, the sand will be electrified and self-repellant, when, instead of falling, as previously, in a straight column, it will be constrained to fall after the manner shown in the figure. To ensure success with this experiment a modification of the rubber is necessary. With this we will deal next time.

OUR HOUSEHOLD INSECTS.

By E. A. BUTLER.
COLEOPTERA (continued).

N order to find the other household members of the

which we were hunting for our first representative of the group the foul churchyard beetle-and visit localities of an altogether different description, viz., bakers' shops, bakehouses, flour-mills, and granaries. Farinaceous substances, such as wheat, barley, maize, meal, flour, bread, cakes, &c., are specially liable to the attacks of various species of beetles, belonging, curiously enough, to several totally distinct sections of the order. In stores of corn in granaries, no less than eighteen species of beetles have been found amongst the refuse, though it is probable that several of these were there, not to eat the grain themselves, but to prey upon such of their associates as were addicted to that practice. Still, it is certain that there is a gang of nearly a dozen species that will engage in this work of destruction whenever they can get a chance, and the ringleaders are those two great sinners, the corn weevils, which we described on a former occasion (See KNOWLEDGE, March 28, 1884). Our old friend, the omnivorous Niptus, too, sometimes joins the ranks of these "corn-lovers,' " and Dr. Power records having found it in hundreds in a quantity of meal, which he transferred to a closely-stoppered bottle, where, notwithstanding that the bottle was never opened, the insects continued to breed for three years, though in gradually decreasing numbers.

But our concern at present is with the Heteromerous members of this gang of freebooters. They are chiefly of small size, and none of them equal Blaps in stature. By far the largest are those whose larvæ constitute the well-known "meal-worms," belonging to the genus Tenebrio, from which the whole family is named the Tenebrionidæ. The meal-worms themselves we reserve for a future notice, and turn our attention at present to the smaller species.

First, we have two very closely allied insects, called Tribolium ferrugineum and T. confusum, the former of which (Fig. 1) is much the commoner. They occupy a position very inferior to the corn-weevils in point of destructiveness, but still they are an enemy not to be despised. They are both small dark reddish-brown insects a colour referred to in the name ferrugineum, “rusty" —of insignificant appearance, and, like several others of the group, do not rightfully belong to the British fauna, having been introduced here with foreign merchandise. They have, however, established themselves, at least under the shelter of human roofs, where they will breed freely, and therefore, though they do not yet appear to have become naturalised in the truly wild condition, they are usually included in lists of British insects.

They are so much alike, that to a casual observer they would appear identical. By a very close and careful comparison under the microscope, minute points of difference in the antennæ, thorax, and punctuation can be made out, but these are of too minute and technical a character to be rendered intelligible here. In the name confusum, the "confused," given to the second species, we have an indication of the difficulty that attends their separation, and of the probability of their being confounded together. There is one peculiarity, however, possessed in common by these insects and their allies which is worth notice. It is that the eyes, which look like piles of tiny, polished black beads, are much encroached upon by a projecting

ridge in front of the head, which is produced backwards in such a way as to appear to have grown partially across the eyes, almost entirely dividing each mass into two unequal parts, one above, the other beneath.

The larvae of these insects are tolerably active, somewhat hairy creatures with six short legs in front. In common with larvæ generally they change their skin several times, each time making their exit from the slough through a slit along the back of the neck, dragging out therefrom, first the segments that afterwards become the thorax, then the head and legs, and finally the abdomen. Previously to assuming the pupal form, they become restless, and search about for a suitable place of lodgment; having found one to its taste, the grub arches its back and divests itself of its last larval skin, and then passes very rapidly through the resting stage of pupadom, appearing in an incredibly short time as a perfect insect, ready again to take part in the activities of life. At first it is pale, and the elytra are so transparent that the body can be seen through them; after a few days, however, they acquire their characteristic ferruginous colour and opacity. The pupa shows distinctly all the parts of the perfect insect, the head, wings, and legs being bent down underneath the body.

These insects do not confine their attentions to farinaceous substances; they are also animal feeders, and are amongst the enemies to be dreaded by the keeper of collections of natural objects; their larvæ will excavate the carcase of a dried insect as effectually as will those of Dermestes or Anthrenus.

Another bakehouse insect is Gnathocerus cornutus, which is identical in colour with Tribolium, and very similar in shape, but somewhat larger. Its names, Gnathocerus, "jaw-horn," and cornutus, "horned," both refer to a peculiarity of the male only, by which that sex can be easily distinguished from all other members of this group. The mandibles, i.e., the biting jaws, are each in the form of a long horn, the pair of which, projecting considerably in front of the head, and curling upwards, give the insect a most formidable aspect. The head is altogether an odd-looking object (Fig. 2), for, besides these mandibular horns, there are two blunt horns on the forehead, and the ridge that almost divides the eyes is produced into a kind of flap or scoop on each side.

By these remarkable structures we are reminded of what seems almost like a law in the insect world, viz., that of all the different parts that make up the whole organism of a typical insect, there are some, such, for example, as the legs, that preserve a very great uniformity of type throughout the class, varying in the different groups, and through the thousands upon thousands of species, only within comparatively narrow limits, while others seem possessed of much greater plasticity, so to speak, and run off occasionally into such eccentricities, extravagances, and apparent monstrosities, that it seems as though there were no limit to the modifications of which they are capable. Perhaps the best illustrations

of this are to be found in the thorax and antennæ, in both of which most marvellous and unexpected developments, both in shape and size, are to be met with. And in our present insect we see the head and mandibles partaking of this same tendency to fantastical modification, a tendency which, so far as mandibles are concerned, is manifested in a most remarkable degree also in the stag-beetle, the "horns" of which are really its jaws. And in that case, too, as in the present, it is in the male sex that the structural peculiarity is found.

A

(To be continued.)

THE DEEP-SEATED ROCKS IN THE
NEIGHBOURHOOD OF LONDON.

MONG the papers read at the meeting of the Geological Society on June 24, were "Supplementary Notes on the Deep Boring at Richmond, Surrey." By Prof. John W. Judd, F.R.S., Sec.G.S., and Collett Homersham, Esq., F.G.S.

Since the author's former communication to the Society on the subject, this boring, in spite of the strenuous efforts made by the Richmond Vestry and the contractors, Messrs. Docwra & Co., has had to be abandoned, after reaching a total depth of 1,447 feet from the surface. This depth is 145 feet greater than that of any other well in the London Basin, and, reckoning from Ordnance Datum, reaches a lower level by 312 feet than any other well in the district.

Before the termination of the work temperature-observations were obtained, which, generally, confirm those previously arrived at.

The strata in which the boring terminated consisted of the red and variegated sandstones and marls previously described, which were proved to the depth of 208 feet. Although it was demonstrated that these beds have a dip of about 30 deg., complicated in places by much false-bedding, no conclusive evidence could be obtained concerning their geological age. They may be referred either to some part of the Poikilitic series, or to the Carboniferous (for similar strata have been found intercalated in the Carboniferous series at Gayton, near Northampton), or they may be regarded as of Old Red Sandstone age.

Some interesting additional observations have been made since the reading of the former paper, on the Cretaceous rocks passed through in this well. Mr. W. Hill, F.G.S., of Hitchin, has found the exact analogue of the curious conglomerated chalk met with at a depth of 704 feet at Richmond. His observations entirely confirm the conclusion that we have at this depth the "Melbourne Rock" with the zone of Belemnites plenus in a remanié condition at its base. Some new facts concerning the state of preservation of the fossils in the Chalk Marl are also recorded.

With respect to the conclusions arrived at by the author concerning the distribution of the Jurassic rocks on the south side of the London Basin, an important piece of confirmatory evidence has been supplied by a deep boring made at the Dockyard-Extension Works at Chatham. This section, for the details of which the authors are indebted to the officers of the Geological Survey, shows that under the Chalk and Gault, with normal characters and thickness, there lie 41 feet of sandy strata of Neocomian age, and that these are directly underlain by blue clays of Middle Oxfordian age, as is proved by the numerous fossils which they have yielded. We have now, therefore, direct evidence of the existence and position of strata of Lower, Middle, and Upper Oolite age, respectively, beneath the Cretaceous rocks of the southeast of England.

IT is said that the applications for space and concessions at the American Exhibition to be opened at Earl's Court, London, on May 1, 1886, are arriving in great numbers.

PEPPERING SPARROWS.-A trouble arises to those who train ivy and other vines on the sides of their dwellings from the noisy sparrows, who make their homes and build their nests in the branches, and chatter and quarrel to the annoyance of their inmates. The writer, after trying many expedients for getting rid of his tormentors, was most successful in the use of shot. A handful flung into the vines had the effect, after a few applications, of driving the chattering throng away, but they returned in less numbers in a few days. But another has tried a plan which we should think would be more effective. He scatters red pepper from a window above into the vines, and he says the birds evinced their dislike to cayenne by taking their departure, and that he has been comparatively free from their annoyance since.

THE

A NEW FLYING-MACHINE.*

HE easy and graceful flight of birds through the air has for the last hundred years been a problem occupying the acutest minds. Attempts have been made during the same period to imitate the motion of the bird in ethereal space, either by the aid of the application of the balloon or by the use of the muscles of the human body alone. Attempts in this direction, although none have as yet been crowned with success, are praiseworthy, and doubtless will in time achieve a fair degree of success. The accompanying engraving represents a flyingmachine, which is the invention of Dr. H. P. Booth, of Chippewa Falls, Wisconsin. The fundamental principle of this flying-machine is in using simultaneously every important muscle of the body for the purpose of elevating the body and propelling it forward through the air.

In harness a man has lifted 3,500 pounds, and this wonderful result is achieved only by allowing every muscle to act simultaneously to its fullest capacity, and under the most advantageous circumstances. This flying machine is merely a harness, by which the human body

the frames of the wings loosely, and runs along the back, forming a pair of loops for the feet to pass through. When the body is forcibly straightened, the wings are brought down with all the power of the most powerful muscles of the body, as is shown in the engraving, and this movement is also assisted by the strong muscles of the arms, operating the wings from the under side. Over the shoulders, extending from one wing to the other, is a strong rubber spring, the tendency of which is to lift the wings, thus assisting the arms in the upward movement. If desired, the hands, instead of operating the wings from the under side, may grasp the short lever forming the base of the wing, and thus make use of more powerful muscles of the arm than if the arms are extended. Which of these is best is, of course, a matter to be determined by experiment. Each wing may be operated independently of the other, it being only necessary to operate one foot or the other to give each wing just such a movement as may be desired. A canvas extends from the base of one wing to the other, forming a sort of stretcher, upon which the operator rests. From the lowest point of the base of the wings are

acts to its best advantage, to the end that it may be both lifted and propelled; and if flying by muscular force alone is ever accomplished, it must be by using all the power there is in the human frame. In this machine there are two wings, each of which is from 12ft. to 15 ft. long, and the breadth equal to the length of the operator, from his shoulders to his feet. The frame of the wings consists of three bamboo poles lashed together, and bent to suitable shape, and covered with silk. A cord extends from one extremity to the other of each of these wings (that is, from the heel to the tip), which serves to give the wing proper shape and tension, being covered by the silk of the wing.

The wings are provided with suitable valves, which open on the upward and close on the downward movement. The frame of the wings forms a right angle in front of the shoulders, and below the breast of the operator, as shown in the engraving, and to these is attached two strong ropes of raw hide. Each of these ropes passes from the wing to which it is attached to the shoulder of the operator, who is supplied with a suitable collar, which supports From the Scientific American.

several small stay ropes running to different points of the wings, which serve to stiffen and strengthen them. In this device the body of the operator offers the least possible resistance to the air, he being in precisely the same attitude that a bird is in during flight. The parts of the apparatus are constructed of the lightest as well as the strongest materials.

SIXPENNY TELEGRAMS.-As we anticipated, sufficient interest in the New Telegraph Acts Amendment Bill has been excited to forbid its summary dismissal. Lord John Manners' statement in the House on Monday evening has met with a very favourable reception, and we may take it for granted that no time will be lost in introducing the reform. Prophesying is dangerous unless you know, but it is safe to express an opinion that we shall be able to use the wires at the reduced rate in October next.

THE Country spent a very large sum of money on the Challenger expedition, and now that the narrative has been published, it has been done under the red-tape rule for dry-as-dust reports, and to cover the cost of production no less than £6. 168. 6d. is being charged on the 750 copies published. Here is a book, the materials for which were obtained at public expense, being published at a price which precludes 99 per cent. of those who would like it from even a hope of getting it. Government encouragement of scientific research will not gain much public favour this way. The Engineer.

Gossip.

BY RICHARD A. PROCTOR.

In an article which I once wrote on "Finding the Way at Sea," I poked a little fun at Mark Twain's odd mistake about the moon at sea. It will be remembered that the mistake was on this wise :-Because the ship, travelling eastwards, made the sun rise (and also set and "south") about twenty minutes earlier day after day, and because the moon rises (and also sets and "souths") about twenty minutes later day after day,therefore the moon remained unchanged to him and his fellow-passengers as they travelled eastwards: "To us Joshuas," as he puts it, "she was a full moon all the time," which of course is absurd. Some one answered in an American paper that it was absurd of me to take Mark Twain in earnest. But this was to insult Mark Twain as a humourist; of course his joke was limited to the introduction of Joshua. If Mr. Blucher had made the mistake about the moon, in anticipation, which Mr. Clemens actually made (the passage having been cloudy I suspect, so that the moon was not seen), Mark Twain might probably, when the mistake was explained, have made very good fun of it. He might, for example, have pictured Mr. Blucher anticipating the delight of a walk by full moonlight in England while friends in New York had only the thin waning moon of the third quarter. Or he might have got good fun out of the idea that while the moon was farther than the earth from the sun for folk in England, she was nearer to the sun than the earth for folk in America. But, unfortunately, falling into the mistake himself, he missed the joke, or rather he made it in his own person.

MARK TWAIN has seemed of late years to have conceived some degree of disgust at science-witness his "Fables for Good Boys, Old and Young." Possibly he thought that his rather laboured jokes at scientific methods and language, might cause men to forget the more splendid joke he had made unwittingly at his very first scientific attempt.

BE this as it may, he has succeeded recently in imagining a scientific blunder almost as funny as his self-made one. Students of science have occasionally extended numbers, good for a particular era, somewhat too boldly into far remote eras in the past and in the future. It has always happened in such cases that other students of science have pointed out the mistake and indicated the limits of time within which such calculations must be kept. Of course, there have been cases where the self-styled religious have made more noise over such points than students of science, as in the famous case where a preacher in America proved to his own satisfaction that Niagara had begun to cut the channel which it assuredly has cut, at about the time assigned by Bishop Usher to the Creation, and was rather staggered at being told that it was awfully wicked of him (by his own showing about others) to say so, for that left no time for the deposition of the rocks cut through, which tell of periods at the very least ten times as long. But usually, outside corrections have been rather petulant than amusing, and science has had the work of sound correction, or the task of exhorting to caution, altogether to herself..

Ir will be understood, then, how much point there is —let the fun in it be what it may-in the following remarks by Mark Twain :—

In the space of 176 years the Lower Mississippi has shortened itself 242 miles. This is an average of a trifle over one and threetenth miles per year. Therefore, any calm person, who is not blind or idiotic, can see that in the old oolitic Silurian period, just 1,000,000 years ago this month, the lower Mississippi was upward of 1,300,000 miles long, and stuck out over the Gulf of Mexico like a fishing-rod. And by the same token any person can see that 742 years from now the Lower Mississippi will only be a mile and three-quarters long, and Cairo and New Orleans will have joined their streets together, and be plodding comfortably along under a single mayor and board of aldermen. There is something fascinating about science. One gets such wholesale returns of conjecture out of such trifling investment of fact.

ALSO, dear humourist, one can so easily make glorious blunders, and get so absurdly and so unnecessarily annoyed over them.

THE Bishop of Hereford, when he was Dr. Jas. Atlay, Fellow and Tutor of St. John's College, Cambridge, and head of the side to which I belonged, used to tell the story, since widely published, of the child who being asked, What is an average? answered "Something on which hens lay eggs." The answer was found perplexing, till she explained that she had seen, a few days before, that hens lay so many eggs a year, on an average. If I remember rightly the answer was given to Dr. Atlay himself.

AND now I hear of a still odder answer, as having been really given at an examination-indeed, like the last, it is too good to have been invented. To the question, “Who was Columbus?" a little girl replied, "Columbus was a large bird." This answer being received, perhaps naturally, with somewhat vociferous laughter, she explained that she had read in an elder sister's book, a piece of poetry about the egg of Columbus, and she did not see how Columbus could have laid an egg unless Columbus was a bird. She thought Columbus must have been a large bird, or they would not have made so much talk about his egg.

THIS little girl was ill-informed respecting Columbus. But was she much more ignorant on this special subject, about which be it remarked she did not pretend to know anything, than a certain archdeacon was of law, when, uninvited, he suddenly amazed lawyers by saying that "Drinking is the only vice of which we can cut off the entail"? which as a well-known writer remarked would imply that Archdeacon F. wished us to obtain the fee simple or possess the whole drinking estate.

OR than the Welsh clergyman, who without any occasion to stagger his audience by astronomical profundities, told them that "So many stars make a planet; so many planets make a constellation; so many constellations make a Milky Way; and six (!) Milky Ways make an Aurora Borealis "?

I WONDER by the way whether in the closing statement of this scientific Welshman, there may not be a sort of development of a story I am fond of telling in one of my lectures-viz., how at a certain middle-class examination, in reply to the question, "What is the Milky Way?" there came the answer,-"The Milky Way is a kind of cloud in the sky, called the Trade Winds, or the Aurora Borealis,"