THE CABBAGE AND PEACOCK BUTTERFLIES.THE CABBAGE AND PEACOCK BUTTERFLIES.
It will be observed that this insect is composed of thirteen segments from head to tail, which is a distinctive characteristic of all insects both in the larval and perfect states; but in the case of this and most other caterpillars these segments are sharply defined and readily recognized. It will also be noticed that the three segments or "joints" nearest the head bear a pair of legs each; these are the real feet, or claspers, as they are sometimes termed, which develop into the feet of the future butterfly. There are four pairs of false feet or suckers, which adhere to the ground by suction, and which disappear in the butterfly. On the last or tail end is a fifth pair of suckers also, which can attach themselves to a surface with considerable force, as any one can attest who has noticed the wrigglings of one of these caterpillars when feeling for new feeding ground.
The caterpillar now ceases to eat, and quietly betakes itself to a secluded corner, where in peace it spins a web around its body, and wrapt therein remains quiescent, awaiting its change into the butterfly. Although so dormant outwardly, activity reigns inside; processes are going on within that chrysalis-case which are the amazement and the puzzle of all naturalists. In course of time the worm is changed into the beautiful winged butterfly, which breaks its case and emerges soft and wet; but it quickly dries and spreads its wings to commence its life in the air and sunshine. The chrysalis is represented in the figure on the left. The butterfly, it will be recognized, is one of the common insects so familiar to all, with strongly veined white wings, bearing three black spots, two on the upper and one on the lower wing, and dark coloring on the corner of the upper wings. The antennæ, as with all butterflies, are clubbed at the extremity—unlike moths', which are tapering—and the large black staring eyes are the optical apparatus, containing, we are told, thousands of lenses, each a perfect, simple eye.
The wings derive their chief coloring from the covering of scales, which lie on like slates on a roof, and are attached in a similar manner. A small portion of the wing magnified is represented at the bottom right hand corner, and detached scales more highly magnifiednext to it, exhibiting somewhat the form of battledoors.
Another well known insect is illustrated in the figure in the upper portion—the peacock butterfly (Vanessa Io). The curious spiked and spotted caterpillar feeds upon the common nettle. This beautiful butterfly—common in most districts—is brilliantly colored and figured on the upper side of the wings, but only of a mottled brown on the under surface, somewhat resembling a dried and brown leaf, so that it is no easy matter to detect the conspicuous, brightly-decked insect when it alights from flight upon foliage, and brings its wings together over its back after the manner of butterflies. At the left-hand corner is seen the head of the insect, magnified, showing the long spiral tongue.
This is a curious structure, and one that will repay the trouble of microscopic examination. In the figure the profile is seen, the large compound eye at the side and the long curved tongue, so elephantine-looking in form, though of minute size, is seen unrolled as it is when about to be inserted into flowers to pump up the honey-juice. This little piece of insect apparatus is a mass of muscles and sensitive nerves comprising a machine of greater complexity and of no less precision in its action than the modern printing machine. When not in use, the tongue rolls into a spiral and disappears under the head. A butterfly's tongue may readily be unrolled by carefully inserting a pin within the first spiral and gently drawing it out.—The Gardeners' Chronicle.
This cypress, apart from its elegant growth, is interesting as being the only species of Cupressus indigenous to India. It is a native of the Himalayas in the Bhotan district, and it also occurs on the borders of Chinese Tartary. It forms, therefore, a connecting link, as it were, between the true cypresses of the extreme east and those that are natives of Europe. It is singular to note that this genus of conifers extends throughout the entire breadth of the northern hemisphere, Cupressus funebris representing the extreme east in China, and C. macrocarpa the extreme west on the Californian seacoast. The northerly and southerly limits, it is interesting to mark, are, on the contrary, singularly restricted, the most southerly being found in Mexico; the most northerly (C. nutkaensis) in Nootka Sound, and the subject of these remarks (C. torulosa) in Bhotan. The whole of the regions intervening between these extreme lateral points have their cypresses. The European species are C. lusitanica (the cedar of Goa), which inhabits Spain and Portugal; C. sempervirens (the Roman cypress), which is centered chiefly in the southeasterly parts of Europe, extending into Asia Minor. Farther eastward C. torulosa is met with, and the chain is extended eastward by C. funebris, also known as C. pendula. The headquarters of the cypresses are undoubtedly in the extreme west, for here may be found some four or five distinct species, including the well-known C. Lawsoniana, probably the most popular of all coniferæ in gardens, C. Goveniana, C. Macnabiana, C. macrocarpa, and C. nutkaensis (spelt C. nutkanus by the Californian botanists). The eastern representative of the cypresses in the United States of North America is C. thyoides, popularly known as the white cedar. In Mexico three or four species occur, so that the genus in round numbers only contains about a dozen species. The Californian botanist Mr. Sereno Watson takes away Lawson's cypress from Cupressus and puts it in the genus Chamæcyparis, the chief points of distinction being the flattened two-ranked branchlets and the small globose cones maturing the first year.
CONES OF CUPRESSUS TORULOSA (NATURAL SIZE).CONES OF CUPRESSUS TORULOSA (NATURAL SIZE).
All the cypresses are undoubtedly valuable from a garden point of view, but the various species vary in degree as regards their utility as ornamental subjects. I should rank them in the following order in point of merit: C. Lawsoniana, C. nutkaensis, C. macrocarpa, C. sempervirens, C. thyoides, C. Macnabiana, and C. Goveniana; then would follow C. torulosa, C. funebris, C. Knightiana, and other Mexican species. These are placed last, not because they are less elegant than the others, but on account of their tenderness, all being liable to succumb to our damp and cold winters. The species which concerns us at present, C. torulosa, is an old introduction, seeds of it having been sent to this country by Wallich so long back as 1824, and previous to this date it was found by Royle on the Himalayas, growing at elevations of some 11,500 feet above sea level. Coming from such a height, one would suppose it to be hardier than it really is, but its tenderness may probably be accounted for by the wood not getting thoroughly ripened during our summers. It is a very handsome tree, said to reach from 20 feet to 125 feet in height in its native habitat. It has a perfectly straight stem; the growth is pyramidal or rather conical, and the old wood is of a warm purplish-brown. The foliage is a glaucous gray-green, and the branches have a twisted and tufted appearance.
There are several varieties of it which are, or have been, in cultivation. Of these one of the best is corneyana, which Gordon ranked as a distinct species. It was supposed to be Chinese, and was introduced to cultivation by Messrs. Knight & Perry, the predecessors of Messrs. Veitch at the Chelsea Nurseries. It differs from C. torulosa proper, its habit being of low stature, and has slender pendulous branches; hence, it has been known in gardens by the names of C. gracilis, C. cernua, and C. pendula. Other varieties of C. torulosa are those named in gardens and nurseries—viridis, a kind devoid of the glaucous foliage of the original; majestica, a robust variety; and nana, a very dwarf and compact-growing sort. There is also a so-called variegated form, but it is not worthy of mention. The synonyms of C. torulosa itself are C. cashmeriana, C. nepalensis, and C. pendula. Having regard to the tenderness of this Bhotan cypress, it should only be planted in the warmest localities, and in dry sheltered positions; upland districts, too, provided they are sheltered, are undoubtedly suitable for it, inasmuch as growth is retarded in spring, and, therefore, the young shoots escape injury from late spring frosts.—W.G., in The Garden.
The variety of the pitcher plant (Sarracenia variolaris) found in North America is carnivorous, being a feeder on various animal substances.
Mrs. Mary Treat, an American naturalist, made, a few years ago, several experiments upon the plants of this species to be found in Florida; and to the labors of this lady the writer has been indebted, in some measure, in the preparation of this paper.
TheSarraceniaderives its name of "pitcher plant" from the fact of its possessing the following curious characteristics: The median nerve is prolonged beyond the leaves in the manner of a tendril, and terminates in a species of cup or urn. This cup is ordinarily three or four inches in depth, and one to one and a half inches in width. The orifice of the cup is covered with a lid, which opens and shuts at certain periods. At sunrise the cup is found filled with sweet, limpid water, at which time the lid is down. In the course of the day the lid opens, when nearly half the water is evaporated; but during the night this loss is made up, and the next morning the cup is again quite full, and the lid is shut.
About the middle of March the plants put forth their leaves, which are from six to twelve inches long, hollow, and shaped something like a trumpet, while the aperture of the apex is formed almost precisely in the same manner as those of the plants previously described. A broad wing extends along one side of the leaf, from the base to the opening at the top; this wing is bound or edged with a purple cord, which extends likewise around the cup. This cord secretes a sweet fluid, and not only flying insects, but those also that crawl upon the ground, are attracted by it to the plants. Ants, especially, are very fond of this fluid, so that a line of aphides, extending from the base to the summit of a leaf, may frequently be observed slowly advancing toward the orifice of the cup, down which they disappear, never to return. Flying insects of every kind are equally drawn to the plant; and directly they taste the fluid, they act very curiously. After feeding upon the secretions for two or three minutes they become quite stupid, unsteady on their feet, and while trying to pass their legs over their wings to clear them, they fall down.
It is of no use to liberate any of the smaller insects; every fly, removed from the leaf upon which it had been feeding, returned immediately it was at liberty to do so, and walked down the fatal cup as though drawn to it by a species of irresistible fascination.
It is not alone that flies and other small insects are overpowered by the fluid which exudes from the cord in question. Even large insects succumb to it, although of course not so quickly. Mrs. Treat says: "A large cockroach was feeding on the secretion of a fresh leaf, which had caught but little or no prey. After feeding a short time the insect went down the tube so tight that I could not dislodge it, even when turning the leaf upside down and knocking it quite hard. It was late in the evening when I observed it enter; the next morning I cut the tube open; the cockroach was still alive, but it was covered with a secretion produced from the inner surface of the tube, and its legs fell off as I extricated it. From all appearance the terribleSarraceniawas eating its victim alive. And yet, perhaps, I should not say 'terrible,' for the plant seems to supply its victims with a Lethe-like draught before devouring them."
If only a few insects alight upon a leaf, no unpleasant smell is perceptible during or after the process of digestion; but if a large number of them be caught, which is commonly the case, a most offensive odor emanates from the cup, although the putrid matter does not appear to injure in any manner the inner surface of the tube, food, even in this condition, being readily absorbed, and going to nourish the plant. In fact, it would seem that theSarracenia, like some animals, can feed upon carrion and thrive upon it.
In instances in which experiments have been made with fresh, raw beef or mutton, the meat has been covered in a few hours with the secretions of the leaves, and the blood extracted from it. There is, however, one difference between the digesting powers of the leaves when exercised upon insects or upon meat. Even if the bodies of insects have become putrid, the plant, as has already been stated, has no difficulty in assimilating them; but as regards meat, it is only when it is perfectly sweet that the secretions of the leaves will act upon it.
The pitcher plant undoubtedly derives its principal nourishment from the insects it eats. It, too—unlike most other carnivorous plants, which, when the quantity of food with which they have to deal is in excess of their powers of digestion, succumb to the effort and die—appears to find it easy to devour any number of insects, small or large, the operation being with it simply a question of time. Flies, beetles, or even cockroaches, at the expiration of three or four days at most, disappear, nothing being left of them save their wings and other hard, parts of their bodies.
TheSarraceniais, indeed, not only the most voracious of all known species of carnivorous plants, but the least fastidious as to the nature of the food upon which it feeds.—W.C.M., Nature.
Mr. Worsley-Benison has been discussing this question in a very interesting way, and he says in conclusion that "physiologicallythe most distinctive feature of plant-life is the power to manufacture protein from less complex bodies; that of animal-life, the absence of such power." He finds that in form, in the presence of starch, of chlorophyl, in power of locomotion, in the presence of circulatory organs, of the body called nitrogen, in the functions of respiration and sensation, there are no diagnostic characters. He finds, however, "fairly constant and well-marked distinctions" in the presence of a cellulose coat in the plant-cell, in digestion followed by absorption, and in the power to manufacture protein.
Themorphologicalfeature of plants is this cellulose coat; of animals, its absence; thephysiologicalpeculiarity of plants, thismanufacturing power; of animals, the want of it. But after all the discussion he says: "To the question,Is this an animal or a plant?we must often reply,We do not know.—The Microscope.
Next to the rose, nofloweris more beautiful or more useful than the camellia. It may readily be so managed that its natural season of blooming shall be from October to March, thus coming in at a time when roses can hardly be had without forcing. In every quality, with the single exception of scent, the camellia may be pronounced the equal of the rose. It can be used in all combinations or for all purposes for which roses can be employed. In form and color it is probably more perfect, and fully as brilliant. It is equally or more durable, either on the plant or as a cut flower. It is a little dearer to buy, and perhaps slightly more difficult to cultivate; but like most plants the camellia has crucial periods in its life, when it needs special treatment. That given, it may be grown with the utmost ease; that withheld, its culture becomes precarious, or a failure. The camellia is so hardy that it will live in the open air in many parts of Great Britain, and herein lies a danger to many cultivators. Because it is quite or almost hardy, they keep it almost cool. This is all very well if the cool treatment be not carried to extremes, and persisted in all the year round. Camellias in a dormant state will live and thrive in any temperature above the freezing point, and will take little or no hurt if subjected to from 3°-4° below it, or a temperature of 27° Fahr.
They will also bloom freely in a temperature of 40°, though 45° suits them better. Hence, during the late summer and early autumn it is hardly possible to keep camellias too cool either out of doors or in. They are also particularly sensitive to heat just before the flower-buds begin to swell in late autumn or winter; a sudden or sensible rise of temperature at that stage sends the flower-buds off in showers. This is what too often happens, in fact, to the camellias of amateurs. No sooner do the buds begin to show then a natural impatience seizes the possessor's of well-budded camellias to have the flowers opened. More warmth, a closer atmosphere, is brought to bear upon them, and down fall the budsin showers on stage or floor—the chief cause of this slip between the buds and the open flowers being a rise of temperature. A close or arid atmosphere often leads to the same results. Camellias can hardly have too free a circulation of air or too low a temperature. Another frequent cause of buds dropping arises from either too little or too much water at the roots. Either a paucity or excess of water at the roots should lead to identical results. Most amateurs overwater their camellias during their flowering stages. Seeing so many buds expanding, they naturally rush to the conclusion that a good deal of water must be used to fill them to bursting point. But the opening of camellia buds is less a manufacture than a mere development, and the strain on the plant and drain on the roots is far less during this stage than many suppose. Of course the opposite extreme of over-dry roots must be provided against, else this would also cause the plants to cast off their buds.
But our object now is less to point out how buds are to be developed into fully expanded flowers than to show how they were to be formed in plenty, and the plants preserved in robust health year after year. One of the simplest and surest modes of reaching this desirable end is to adopt a system of semi-tropical treatment for two months or so after flowering. The moment or even before the late blooms fade, the plants should be pruned if necessary. Few plants bear the knife better than camellias, though it is folly to cut them unless they are too tall or too large for their quarters or have grown out of form. As a rule healthy camellias produce sufficient or even a redundancy of shoots without cutting back; but should they need pruning, after flowering is the best time to perform the operation.
During the breaking of the tender leaves and the growth of the young shoots in their first stages, the plant should be shaded from direct sunshine, unless, indeed, they are a long way from the glass, when the diffusion and dispersion of the rays of light tone down or break their scorching force; few young leaves and shoots are more tender and easily burned than camellia, and scorching not only disfigures the plants, but also hinders the formation of fine growths and the development of flower-buds.
The atmosphere during the early season of growth may almost touch saturation. It must not fail to be genial, and this geniality of the air must be kept up by the surface-sprinkling of paths, floors, stages, walls, and the plants themselves at least twice a day.
With the pots or border well drained it is hardly possible to overwater the roots of camellias during their period of wood-making. The temperature may range from 50° to 65° during most of the period. As the flower-buds form, and become more conspicuous, the tropical treatment may become less and less tropical, until the camellias are subjected to the common treatment of greenhouse or conservatory plants in summer. Even at this early stage it is wise to attend to the thinning of the buds. Many varieties of camellias—notably that most useful of all varieties, the double white—will often set and swell five or ten times more buds than it ought to be allowed to carry. Nothing is gained, but a good deal is lost, by allowing so many embryo flower-buds to be formed or partially developed. It is in fact far wiser to take off the majority of the excess at the earliest possible point, so as to concentrate the strength of the plant into those that remain.
As it is, however, often a point of great moment to have a succession of camellia flowers for as long a period as possible on the same plants, buds of all sizes should be selected to remain. Fortunately, it is found in practice that the plants, unless overweighted with blooms, do not cast off the smaller or later buds in their efforts to open their earlier and larger ones. With the setting, thinning, and partial swelling of the flower-buds the semi-tropical treatment of camellias must close; continued longer, the result would be their blooming out of season, or more probably their not blooming at all.
The best place for camellias from the time of setting their flower-buds to their blooming season is a vexed question, which can hardly be said to have been settled as yet. They may either be left in a cool greenhouse, or placed in a shaded, sheltered position in the open air. Some of the finest camellias ever seen have been placed in the open air from June to October. These in some cases have been stood behind south, and in others behind west walls. Those facing the east in their summer quarters were, on the whole, the finest, many of them being truly magnificent plants, not a few of them having been imported direct from Florence at a time when camellias were far less grown in England than now.
In all cases where camellias are placed in the open air in summer, care will be taken to place the pots on worm proof bases, and to shield the tops from direct sunshine from 10 to 4 o'clock. If these two points are attended to, and also shelter from high winds, it matters little where they stand. In all cases it is well to place camellias under glass shelter early in October, less for fear of cold than of saturating rains causing a sodden state of the soil in the pots.
While adverting, however, to the safety and usefulness of placing camellias in the open air in summer, it must not be inferred that this is essential to the successful culture; it is, in fact, far otherwise, as the majority of the finest camellias in the country are planted out in conservatories with immovable roofs. Many such houses are, however, treated to special semi-tropical treatment as has been described, and are kept as cool and open as possible after the flower-buds are fairly set, so that the cultural and climatic conditions approximate as closely as possible to those here indicated.
Soil and seasons of potting may be described as vexed questions in camellia culture. As to the first, some affect pure loam, others peat only, yet more a half and half of both, with a liberal proportion of gritty sand, or a little smashed charcoal or bruised bones as porous or feeding agents, or both. Most growers prefer the mixture, and as good camellias are grown in each of its constituents, it follows without saying that they may also be well grown in various proportions of both.
Under rather than over potting suits the plants best, and the best time is doubtless just before they are about to start into fresh growth, though many good cultivators elect to shift their plants in the late summer or autumn, that is, soon after the growth is finishing, and the flower-buds fairly and fully set for the next season. From all which it is obvious that the camellia is not only among the most useful and showy, but likewise among the most accommodating of plants.
Under good cultivation it is also one of the cleanest, though when scab gets on it, it is difficult to get rid of it. Mealy-bugs also occasionally make a hurried visit to camellias when making their growth, as well as aphides. But the leaves once formed and advanced to semi-maturity are too hard and leathery for such insects, while they will bear scale being rubbed off them with impunity. But really well-grown camellias, as a rule, are wholly free from insect pests, and their clean, dark, glossy leaves are only of secondary beauty to their brilliant, exquisitely formed, and many sized flowers.—D.T., The Gardeners' Chronicle.
ARISÆMA FIMBRIATUM: LEAF, SPATHE, ANDARISÆMA FIMBRIATUM: LEAF, SPATHE, AND FLORAL DETAILS.
Some few years since we had occasion to figure some very remarkable Himalayan species of this genus, in which the end of the spadix was prolonged into a very long, thread-like appendage thrown over the leaves of the plant or of its neighbors, and ultimately reaching the ground, and thus, it is presumed, affording ants and other insects means of access to the flowers, and consequent fertilization. These species were grown by Mr. Elwes, and exhibited by him before the Scientific Committee. The present species is of somewhat similar character, but is, we believe, new alike to gardens and to science. We met with it in the course of the autumn in the nursery of Messrs. Sander, at St. Alban's; but learn that it has since passed into the hands of Mr. W. Bull, of Chelsea. It was imported accidentally with orchids, probably from the Philippine Islands. It belongs to Engler's section, trisecta, having two stalked leaves, each deeply divided into three ovate acute glabrous segments. The petioles are long, pale purplish, rose-colored, sprinkled with small purplish spots. The spathes are oblong acute or acuminate, convolute at the base, brownish-purple, striped longitudinally with narrow whitish bands. The spadix is cylindrical, slender, terminating in along, whip-like extremity, much longer than the spathe. The flowers have the arrangement and structure common to the genus, the females being crowded at the base of the spadix, the males immediately above them, and these passing gradually into fleshy incurved processes, which in their turn pass gradually into long, slender, purplish threads, covering the whole of the free end of the spadix.—M.T.M., in The Gardeness' Chronicle.
In the new edition of Mason's "Burma" we read that among other uses to which the bamboo is applied, not the least useful is that of producing fire by friction. For this purpose a joint of thoroughly dry bamboo is selected, about 1½ inches in diameter, and this joint is then split in halves. A ball is now prepared by scraping off shavings from a perfectly dry bamboo, and this ball being placed on some firm support, as a fallen log or piece of rock, one of the above halves is held by its ends firmly down on it, so that the ball of soft fiber is pressed with some force against its inner or concave surface. Another man now takes a piece of bamboo a foot long or less, and shaped with a blunt edge, something like a paper knife, and commences a sawing motion backward and forward across the horizontal piece of bamboo, and just over the spot where the ball of soft fiber is held. The motion is slow at first, and by degrees a groove is formed, which soon deepens as the motion increases in quickness. Soon smoke arises, and the motion is now made as rapid as possible, and by the time the bamboo is cut through not only smoke but sparks are seen, which soon ignite the materials of which the ball beneath is composed. The first tender spark is now carefully blown, and when well alight the ball is withdrawn, and leaves and other inflammable materials heaped over it, and a fire secured. This is the only method that I am aware of for procuring fire by friction in Burma, but on the hills and out of the way parts, that philosophical toy, the "pyrophorus," is still in use. This consists1of a short joint of a thick woody bamboo, neatly cut, which forms a cylinder. At the bottom of this a bit of tinder is placed, and a tightly-fitting piston inserted composed of some hard wood. The tube being now held in one hand, or firmly supported, the piston is driven violently down on the tinder by a smart blow from the hand, with the result of igniting the tinder beneath.
Another method of obtaining fire by friction from bamboos is thus described by Captain T.H. Lewin ("Hill Tracts of Chittagong, and the DwellersTherein", Calcutta, 1869, p. 83), as practiced in the Chittagong Hills. The Tipporahs make use of an ingenious device to obtain fire; they take a piece of dry bamboo, about a foot long, split it in half, and on its outer round surface cut a nick, or notch, about an eighth of an inch broad, circling round the semi-circumference of the bamboo, shallow toward the edges, but deepening in the center until a minute slit of about a line in breadth pierces the inner surface of the bamboo fire-stick. Then a flexible strip of bamboo is taken, about 1½ feet long and an eighth of an inch in breadth, to fit the circling notch, or groove, in the fire-stick. This slip or band is rubbed with fine dry sand, and then passed round the fire-stick, on which the operator stands, a foot on either end. Then the slip, grasped firmly, an end in each hand, is pulled steadily back and forth, increasing gradually in pressure and velocity as the smoke comes. By the time the fire-band snaps with the friction there ought to appear through the slit in the fire-stick some incandescent dust, and this placed, smouldering as it is, in a nest of dry bamboo shavings, can be gently blown into a flame.—The Gardeners' Chronicle.
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It is also made of a solid cylinder of buffalo's horn, with a central hollow of three-sixteenths of an inch in diameter and three inches deep burnt into it. The piston, which fits very tightly in it, is made of iron-wood or some wood equally hard.
It is also made of a solid cylinder of buffalo's horn, with a central hollow of three-sixteenths of an inch in diameter and three inches deep burnt into it. The piston, which fits very tightly in it, is made of iron-wood or some wood equally hard.
When we read how one mediæval saint stood erect in his cell for a week without sleep or food, merely chewing a plantain-leaf out of humility, so as not to be too perfect; how another remained all night up to his neck in a pond that was freezing over; and how others still performed for the glory of God feats no less tasking to their energies, we are inclined to think, that, with the gods of yore, the men, too, have departed, and that the earth is handed over to a race whose will has become as feeble as its faith. But we ought not to yield to these instigations, by which the evil one tempts us to disparage our own generation. The gods have somewhat changed their shape, 'tis true, and the men their minds; but both are still alive and vigorous as ever for an eye that can look under superficial disguises. The human energy no longer freezes itself in fish-ponds, and starves itself in cells; but near the north pole, in central Africa, on Alpine "couloirs," and especially in what are nowadays called "psycho-physical laboratories," it maybe found as invincible as ever, and ready for every fresh demand. To most people a north pole expedition would be an easy task compared with those ineffably tedious measurements of simple mental processes of which Ernst Heinrich Weber set the fashion some forty years ago, and the necessity of extending which in every possible direction becomes more and more apparent to students of the mind. Think of making forty thousand estimates of which is the heavier of two weights, or seventy thousand answers as to whether your skin is touched at two points or at one, and then tabulating and mathematically discussing your results! Insight is to be gained at no less price than this. The new sort of study of the mind bears the same relation to the older psychology that the microscopic anatomy of the body does to the anatomy of its visible form, and the one will undoubtedly be as fruitful and as indispensable as the other.
Dr. Ebbinghaus1makes an original addition to heroic psychological literature in the little work whose title we have given. For more than two years he has apparently spent a considerable time each day in committing to memory sets of meaningless syllables, and trying to trace numerically the laws according to which they were retained or forgotten. Most of his results, we are sorry to say, add nothing to our gross experience of the matter. Here, as in the case of the saints, heroism seems to be its own reward. But the incidental results are usually the most pregnant in this department; and two of those which Dr. Ebbinghaus has reached seems to us to amply justify his pains. The first is, that, inforgettingsuch things as these lists of syllables, the loss goes on very much more rapidly at first than later on. He measured the loss by the number of seconds required torelearnthe list after it had been once learned. Roughly speaking, if it took a thousand seconds to learn the list, and five hundred to relearn it, the loss between the two learnings would have been one-half. Measured in this way, full half of the forgetting seems to occur within the first half-hour, while only four-fifths is forgotten at the end of a month. The nature of this result might have been anticipated, but hardly its numerical proportions.
The other important result relates to the question whether ideas are recalled only by those that previously came immediately before them, or whether an idea can possibly recall another idea, with which it was never inimmediatecontact, without passing through the intermediate mental links. The question is of theoretic importance with regard to the way in which the process of "association of ideas" must be conceived; and Dr. Ebbinghaus' attempt is as successful as it is original, in bringing two views, which seem at first sight inaccessible to proof, to a direct practical test, and giving the victory to one of them. His experiments conclusively show that an idea is not only "associated" directly with the one that follows it, and with the restthrough that, but that it isdirectlyassociated withallthat are near it, though in unequal degrees. He first measured the time needed to impress on the memory certain lists of syllables, and then the time needed to impress lists of the same syllables with gaps between them. Thus, representing the syllables by numbers, if the first list was 1, 2, 3, 4 ... 13, 14, 15, 16, the second would be 1, 3, 5 ... 15, 2, 4, 6 ... 16, and so forth, with many variations.
Now, if 1 and 3 in the first list were learned in thatorder merely by 1 calling up 2, and by 2 calling up 3, leaving out the 2 ought to leave 1 and 3 with no tie in the mind; and the second list ought to take as much time in the learning as if the first list had never been heard of. If, on the other hand, 1 has adirectinfluence on 3 as well as on 2, that influence should be exerted even when 2 is dropped out; and a person familiar with the first list ought to learn the second one more rapidly than otherwise he could. This latter case is what actually occurs; and Dr. Ebbinghaus has found that syllables originally separated by as many as seven intermediaries still reveal, by the increased rapidity with which they are learned in order, the strength of the tie that the original learning established between them, over the heads, so to speak, of all the rest. It may be that this particular series of experiments is the entering wedge of a new method of incalculable reach in such questions. The future alone can show. Meanwhile, when we add to Dr. Ebbinghaus' "heroism" in the pursuit of true averages, his high critical acumen, his modest tone, and his polished style, it will be seen that we have a new-comer in psychology from whom the best may be expected.—W.J., Science.
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"Ueber das Gedächtniss. Untersuchungen zur experimentellenPsychologie."Von Herm. Ebbinghaus. Leipzig: Duncker u. Humblot, 1885. 10+169 pp. 8vo.
"Ueber das Gedächtniss. Untersuchungen zur experimentellenPsychologie."Von Herm. Ebbinghaus. Leipzig: Duncker u. Humblot, 1885. 10+169 pp. 8vo.
The sinking of mine shafts in certain Belgian and French basins, where the coal deposit is covered with thick strata of watery earth, has from all times been considered as the most troublesome and delicate, and often the most difficult operation, of the miner's art. Of the few modern processes that have been employed for this purpose, that of Messrs. Kind and Chaudron has been found most satisfactory, although it leaves much to be desired where it is a question of traversing moving sand. An interesting modification of this well-known process has recently been described by Mr. E. Chavatte, in the Bulletin de la Societe Industrielle du Nord de la France. Two years ago the author had to sink a working shaft at Quievrechain, 111 feet of which was to traverse a mass of moving and flowing sand, inconsistent earth, gravel, and marls, and proceeded as follows:
He first put down two beams, A B (Pl. 1, Figs. 2, 3, and 9), each 82 feet in length and of 20×20 inch section in the center, and upon these placed two others, E F, of 16×16 inch section. Beneath the two first were inserted six joists,c c c c c c, about 82 feet in length and of 14 or 16 inch section in the center. Finally these were strengthened at their extremities with two others,d d, about 82 feet in length. All these timbers, having been connected by tie bands and bolts, constituted a rigid structure that covered a surface of nearly seven hundred square yards.
From the beams, A B and E F, there was suspended a red fir frame by means of thirty-four iron rods.
Upon this frame, which was entirely immersed in the moving sand, there was established brick masonry (Figs. 1, 2, and 3). As the ends of the timbers entered the latter, and were connected by 1½ inch bolts, they concurred in making the entire affair perfectly solid. The frame, K K, was provided with an oaken ring, which was affixed to it with bolts.
After this, a cast iron tubbing, having a cutting edge, and being composed of rings 3.28 feet wide and made of six segments, was lowered. This tubbing was perfectly tight, all the surfaces of the joints having been made even and provided with strips of lead one-tenth of an inch thick. It weighed 4,000 pounds to the running foot.
Plate I—SINKING A MINE SHAFTFig.1.—Section through A B.Fig.2.—Plan.Fig.3.—Section through C D.Fig.5.—Section through E F of Fig. 4.Figs. 6 and7.—Work Prepared and finished.Fig.10.—Section through A B and C D of Fig. 12.Figs.11 6and12.—Arrangement of jack-screw.Fig.13.—Section through A B and C D of Fig. 11.PlateI.—SINKING A MINE SHAFT.
Fig.1.—Section through A B.Fig.2.—Plan.Fig.3.—Section through C D.Fig.5.—Section through E F of Fig. 4.Figs. 6 and7.—Work Prepared and finished.Fig.10.—Section through A B and C D of Fig. 12.Figs.11 6and12.—Arrangement of jack-screw.Fig.13.—Section through A B and C D of Fig. 11.
Fig.1.—Section through A B.Fig.2.—Plan.Fig.3.—Section through C D.Fig.5.—Section through E F of Fig. 4.Figs. 6 and7.—Work Prepared and finished.Fig.10.—Section through A B and C D of Fig. 12.Figs.11 6and12.—Arrangement of jack-screw.Fig.13.—Section through A B and C D of Fig. 11.
PlateI.—SINKING A MINE SHAFT.
It was first raised to a height of fifteen feet, so as to cause it to enter the sand by virtue of its own gravity. It thus penetrated to a depth of about twenty inches. After this the workmen were ordered to man the windlasses and hoist out some of the sand. This caused the tubbing to descend about eight inches more, when it came to a standstill. It was now loaded with 17,000 pounds of pig iron, but in vain, for it refused to budge. Mr. Chavatte therefore had recourse to a dredge with vertical axis, constructed as follows:
Upon a square axis, A B (Pl. 2, Figs. 1, 2, and 3), provided with double cross braces, C D, and strengthened by diagonals, were riveted, by their upper extremities, two cheeks, G H, whose lower extremities held the steel plates, I J I' J', which, in turn, were fastened to the axis, A B, by their other extremities. These plates were so inclined as to scrape the surface of the ground over which they were moved. They each carried two bags made of coarse canvas and strengthened by five strong leather straps (Figs. 2 and 4). To the steel plates were riveted two plates of iron containing numerous apertures, through which passed leather straps designed for fastening thereto the lower part of the mouth of the bags. That portion of the mouth of the latter that was to remain open was fastened in the same way to two other plates, X Y, X¹ Y¹ (Fig. 1), held between the lower cross-braces.
When the apparatus was revolved, the plates scraped the earth to be removed, and descended in measure as the latter entered the bags. These bags, when full, were hooked, by means of the five rings which they carried, to the device shown in Fig. 8 (Pl. 2), and raised to the surface and emptied into cars.
The dredge was set in motion by four oak levers (Figs. 5 and 6). Two of these were manned by workmen stationed upon the surface flooring, and the other two by workmen upon the flooring in the tubbing. The axis was elongated, in measure as the apparatus descended, by rods of the same dimensions fastened together by cast iron sleeves and bolts (Fig. 7).
The steel plates were not capable of acting alone, even in cases where they operated in pure moving sand containing no pebbles, for the sand was too compact to be easily scraped up by the steel, and so it had to be previously divided. For this purpose Mr. Chavatte used rakes which were in form exactly like those of the extirpators, U and V, of Figs. 1, 2, and 3, of Pl. 2, except that the dividers carried teeth that were not so strong as those of the extirpators, and that were set closer together. These rakes were let down and drawn up at will. They were maneuvered as follows:
The dredge descended with the extirpators pointing upward. When their heads reached the level of the upper floor, the tools were removed. Then the dredge was raised again. In this way the extirpators lay upon the floor, and, if the lifting was continued, they placed themselves in their working position, in which they were fixed by the bolts A" B" C" (Fig. 1). After this, the apparatus was let down and revolved. The rakes divided the earth, the scrapers collected it, and the bags pocketed it.
The great difficulty was to cause the tubbing to descend vertically, and also to overcome the enormous lateral pressure exerted upon it by the earth that was being traversed. Water put into the shaft helped somewhat, but the great stress to be exerted had to be effected by means of powerful jack screws. These were placed directly upon the tubbing, and bore against strong beams whose extremities were inserted into the masonry.
As a usual thing it is not easy to use more than four or six such jacks, since the number of beams that can be employed is limited, owing to the danger of obstructing the mouth of the shaft. Yet twelve were used by Mr. Chavatte, and this number might have been doubled had it been necessary. As we have seen, the frame, K K (Pl. 1, Fig. 3), was provided with an oak circle traversed by 32 bolts. The length of these latter was two inches and a quarter longer than they needed to have been, or they were provided with wooden collars of that thickness. Later on, these collars were replaced with iron bars that held the wood against which the jacks bore in order to press the tubbing downward (Pl. 1, Figs. 10, 11, 12, and 13).
Mr. Chavatte's great anxiety was to know whether he should succeed in causing the first section of tubbing to traverse the four feet of gravel; for in case it did not pass, he would be obliged to employ a second section of smaller diameter, thus increasing the expense. He was persuaded that the coarse gravel remaining in the side of the shaft would greatly retard the descent of the tubbing. So he had decided to remove such obstructions at the proper moment through divers or a diving bell. Then an idea occurred to him that dispensed with all that trouble, and allowed him to continue with the first section. This was to place upon the dredge two claw-bars, T (Pl. 2, Fig. 3), which effected the operation of widening with wonderful ease. To do this it was only necessary to turn up the bags, and revolve the apparatus during its descent. The claw at the extremity of the bar pulled out everything within its reach, and thus made an absolutely free passage for the tubbing.
The sands and gravels were passed by means of a single section of tubbing 31 feet in length, which was not stopped until it had penetrated a stratum of white chalk to a depth of two yards. This chalk had no consistency, although it contained thin plates of quite large dimensions. These were cut, as if with a punch, by means of the teeth of the extirpator.
It now remains to say a few words concerning the sinking of the shaft, which, after the operation of the dredge, was continued by the process called "natural level" The work was not easy until a depth of 111 feet had been reached. Up to this point it had been necessary to proceed with great prudence, and retain the shifting earth by means of four iron plate tubes weighing 54 tons. Before finding a means of widening the work already done by the dredge, Mr. Chavatte was certain that he would have to use two sections of tubbing, and so had given the first section a diameter of 16½ feet. He could then greatly reduce the diameter, and bring it to 15¾ feet as soon as the ground auger was used.
After two yards of soil had been removed from beneath the edge of the tubbing, the earth began to give way. Seeing this, Mr. Chavatte let down a tube 13 feet in length and 15.4 in diameter. The exterior of thiswas provided with 12 oak guides, which sliding over the surface of the tubbing had the effect of causing the tube to descend vertically. And this was necessary, because this tube had to be driven down every time an excavation of half a yard had been made.
Afterward, a diameter of 15.35 feet was proceeded with, and the small central shaft of 4¼ feet diameter was begun. This latter had not as yet been sunk, for fear of causing a fall of the earth.
Next, the earth was excavated to a depth of 8.2 feet, and a tube 16.4 feet in length was inserted; then a further excavation of 8.2 feet was made, and the tube driven home.
After this an excavation of 26¼ feet was made, and a tube of the same length and 14½ feet in diameter was driven down. Finally, the shifting soil was finished with a fourth tube 19½ feet in length and 14 feet in diameter.
A depth of 111 feet had now been reached, and the material encountered was solid white chalk. From this point the work proceeded with a diameter of 13.9 feet to a depth of 450 feet. The small shaft had been sunk directly to a depth of 475 feet. At 450 feet the diameter was diminished by three inches. Then an advance of a foot was made, and the diameter reduced by one and a half inch.
The reason for this reduction in the diameter and change in the mode of deepening was as follows:
The Chaudron moss-box, when it chances to reach its seat intact, and can consequently operate well, undoubtedly makes a good wedging. But how many times does it not happen that it gets injured before reaching its destination? Besides, as it often rests upon earth that has caved in upon its seat during the descent of the tubbing, it gets askew, and later on has to be raised on one side by means of jacks or other apparatus. Under such circumstances, Mr. Chavatte considered this moss-box as more detrimental than useful, and not at all indispensable, and so substituted beton for it, as had previously been done by Mr. Bourg, director of the Bois-du-Luc coal mines.