"The Short-tailed Field Mouse (Arvicola arvalis) is found throughout Europe to Siberia. Small and insignificant as this animal appears to be, there is scarcely a species among the rodents more destructive to our fields, gardens, and woods. In the corn-field, the rick-yard, the granary, and in extensive plantations, its depredations are often severe, and even calamitous. Of the damage effected by a multitude of these animals we give a single instance. In the year 1814 the whole, both of Dean and New Forest, appeared to be largely stocked with mice; at least wherever the large furze-brakes in the open parts had been burnt their holes and runs covered the surface. Hayward Hill, a new plantation of about 500 acres in the Forest of Dean, was particularly infested. This inclosure, after being properly fenced, was planted with acorns in 1810, and in the following spring about one-third came up, the rest of the seed having been destroyed principally by mice. The young shoots of the natural hollies of the district, which had been cut down to favour the plantation, were not attacked by the mice in the following winter, though their runs were numerous. In the autumn of the succeeding year a large quantity of five years old oaks and chestnuts, with ash, larch, and fir, were planted in the inclosure. In the winter the destruction began, and numbers of the hollies, then two, three, or more feet in height, were barked round from the ground to four or five inches upwards, and died. In the succeeding spring a number of the oaks and chestnuts were found dead; and when they were pulled up it appeared that the roots had been gnawed through two or three inches below the surface of the ground; many were also barked round and killed, like the holly-shoots, whilst others, which had been begun upon, were sickly. The evil now extended to the other inclosures, and becoming very serious both in Dean Forest and the New Forest, cats were turned out, the bushes, ferns, rough grass, and other plants were cleared off to expose the mice to beasts and birds of prey; poisons in great variety were laid, and seven or eight different sorts of traps were set for them, some of which succeeded very well. These were, however, superseded by the plan of a ratcatcher, who, having been employed to capture the mice, had observed, on going to work in the morning, that some of them had fallen into wells or pits accidentally formed, and could not get out again, many of them dying from hunger or fatigue in endeavouring to climb up the sides. Such pits were therefore tried on his recommendation. They were at first made three feet deep, three long, and two wide; but these were found to be unnecessarily large, and after various experiments it appeared that they answered best when from eighteen to twenty inches deep, about two feet in length, and a foot and a half in width at the bottom, and only eighteen inches long and nine wide at the top, or so wide as would allow of the earth being got out of a hole of that depth, for the wider they were below and the narrower above the better they answered their purpose. They were made about twenty yards asunder, or, where the mice were less numerous, thirty yards apart. Nearly 30,000 mice were speedily caught by this method in Dean Forest, and in the New Forest about 10,000 more. It was believed that a far greater number had been taken out of the holes either alive or dead by stoats and weasels, or by kites, owls, crows, jays, and magpies." The following account of the Angler (Lophius piscatorius), a curious large-headed fish belonging to the family of the Lophiida, or fishing-frogs, and a native of our seas, is short, but clear and instructive :-"This curious fish has the head wide, and the mouth nearly as wide as the head; the eyes are large; the lower jaw, which is the longer, is bearded or fringed all round the edge, and both jaws are armed with numerous teeth; the body is narrow compared with the breadth of the This is the form adopted for the tiger-pits made by the Chinese in Singapore. head, and tapers gradually to the tail. The colour of the upper surface of the body is uniform brown, the under surface white, and the tail almost black. On the top of the head are three long filaments; of these, two are seated just above the muzzle, the other rises from the back of the head. These filaments are movable in all directions, especially the first, which, tapering like the finest fishing-rod, ends in broad, flattened, silvery tips. "The angler is insatiably voracious, but it is a slow swimmer; it is formed, in fact, for taking its prey in ambush. It reposes on the soft mud or sand, in some favourable lurking-place, and, stirring up the mud with its pectoral fins, thus obscures itself in a murky cloud, beyond which appear its long filaments, and, especially the first, with its glittering tip, offering an attractive bait to other fish. Thus stationed, the creature quietly expects its victim. On rove the shoals of fish, eager in quest of food. They pass one after another in succession, till at length one espies the bait. Forward the fish darts, either to examine or seize the expected prize; but at that instant, aided by its broad, feet-like pectoral fins, the watchful angler springs up and captures its prey." The fishes are generally very well illustrated, and a large number of interesting species are described. Passing on to the invertebrates, we come first to the insects, which form the weakest part of the volume; but this is perhaps of less importance as none but specialists feel any interest in the bulk of the forms; while their immense numbers and endless variety, their strange habits, and marvellous instincts can only be adequately set forth where ample space can be afforded them. We pass on therefore to the lower marine animals, and select as an example of the way they are treated a rare British species allied to the sea cucumbers, and named Synapta duvernea. It was discovered in the English Channel by M. Quatrefages, who thus describes it : Imagine a cylinder of rose-coloured crystal as much as eighteen inches long and more than an inch in diameter, traversed in all its length by five narrow ribbands of white silk, and its head surmounted by a living flower whose twelve tentacles of purest white fall behind in a graceful curve. In the centre of these tissues, which rival in their delicacy the most refined products of the loom, imagine an intestine of the thinnest gauze, gorged from one end to the other with coarse grains of granite, the rugged points and sharp edges of which are perfectly perceptible to the naked eye. But what most struck me at first in this animal was that it seemed literally to have no other nourishment than the coarse sand by which it was surrounded. And then when, armed with scalpel and microscope, I ascertained something of its organisation, what unheard-of marvels were revealed! In this body, the walls of which scarcely reach the sixteenth part of an inch in thickness, I could distinguish seven distinct layers of tissue, with a skin, muscles, and membranes. Upon the petaloid tentacles I could trace terminal suckers, which enabled the Synapta to crawl up the side of a highly-polished vase. In short this creature, denuded to all appearance of every means of attack or defence, showed itself to be protected by a species of mosaic, formed of small, calcareous, shield-like defences, bristling with double hooks, the points of which, dentated like the arrows of the Carribeans, had taken hold of my hands. If one of these Synapta is preserved alive in sea-water for a short time, and subjected to a forced fast, a very strange phenomenon will be observed. The animal, being unable to feed itself, successively detaches various parts of its own body, which it amputates spontaneously." Although most of the illustrations in this volume are very good, and some are good works of art, there are also several which are very poor, and quite unworthy of the text. This is especially the case among the smaller birds, several of which are unrecognisable. A few also have been wrongly named, representing very different creatures from those they are said to be. The most prominent defects of this kind are the figure of the Leucoryx antelope, which is named Saiga tartarica, and that of two humming-birds, which do duty for sun-birds. These oversights, which no doubt occurred in the London office, since they are far too gross to be imputed to the author of the book, should be corrected in another edition; and if the publishers will substitute better figures for those of the stone chat, hedge-sparrow, dipper, Javasparrows and some others which are barely recognisable, the work will be one of permanent use and interest, both as an illustrated manual of the families of the vertebrata and a popular introduction to general natural history. A. R. W. I have endeavoured to trace the various effects on the configuration of a planet and satellite, which must result from tidal friction-the tides in the planet being either a bodily distortion or oceanic. The investigations are, I think, not without interest as a branch of pure dynamics, but this side of the subject is too complicated to be made intelligible without mathematical notation, and it would occupy too much space to explain the methods of treatment. There is, however, another side of the subject, which raust, I think, attract notice, or at least criticism, and this is the applicability of the results of analysis to the history of the earth and of the other planets. We know that no solids are either perfectly rigid or perfectly elastic, and that no fluids are devoid of internal friction, and therefore the tides raised in any planet, whether consisting of oceanic tides or of a bodily distortion of the planet, must be subject to friction. From this it follows that the dynamical investigation must be applicable to some extent to actual planets and satellites. For myself, I believe that it gives the clue to the history of the system, but of course an ample field for criticism is here opened. The investigation is intended to be more especially applicable to the case of the earth and moon, and therefore, instead of planet and satellite, the expressions earth and moon are used. The effect of tidal friction upon the eccentricity and inclination of the lunar orbit here affords the principal topic. The obliquity of the ecliptic, the diurnal rotation of the earth, and the moon's periodic time were considered in a paper read before the Royal Society on December 19, 1878, and which will appear in the Philosophical Transactions for 1879. The present paper completes (as far as I now see) the main investigation for the case of the earth and moon, and therefore it is now possible to bring the various results to a focus. It appears then that, when we trace backwards in time the changes induced in the system of the earth and moon by tidal friction, we are led to an initial state which is defined as follows::- The earth and moon are found to be initially nearly in contact; the moon always opposite the same face of the earth, or moving very slowly relatively to the earth's surface; the whole system rotating in from two to four hours, about an axis inclined to the normal to the ecliptic at an angle of 11° 45′, or somewhat less; and the moon moving in a circular orbit, the plane of which is nearly coincident with the earth's equator. This initial configuration suggests that the moon was produced by the rupture, in consequence of rapid rotation or other causes, of a primeval planet, whose mass was made up of the present earth and moon. The coincidence is noted in the paper, that the shortest period of revolution of a fluid mass of the same mean density as the earth, which is consistent with an ellipsoidal form of equilibrium, is two hours twenty-four minutes; and that if the moon were to revolve about the earth with this periodic time, the surfaces of the two bodies would be almost in contact with one another. The rupture of the primeval planet into two parts is a matter of speculation, but if a planet and satellite be given in the initial configuration above described, then a system bearing a close resemblance to our own, would necessarily be evolved under the influence of tidal friction. The theory postulates that there is not sufficient diffused matter to materially resist the motions of the moon and earth through space. Sufficient lapse of time is also required. In a previous paper I showed that the minimum time in which the system could have degraded from the initial state, just after the rupture into two bodies, down to the present state, is fifty-four million years. The time actually occupied by the changes would certainly be much longer. It appears to me that a theory, reposing on a vera causa, which brings into quantitative correlation the lengths of the present day and month, the obliquity of the ecliptic and the inclination and eccentricity of the lunar orbit, must have considerable claims to acceptance. It was stated that the periodic times of revolution and rotation of the moon and earth might be traced back to a common period of from two to four hours. In a previous paper the common period was found to be a little over five hours in length; but that result was avowedly based on a partial neglect of the sun's attraction. In this paper certain further considerations are adduced, which show that, while the general principle remains intact, yet the common period of revolution of the earth and moon must initially have been shorter than five hours to an amount which is uncertain, but is probably large. The period of from two to four hours is here assigned, because it is mechanically impossible for the moon to revolve about the earth in less than two hours, and it is uncertain how the rupture of the primeval planet took place. But if tidal friction has been the agent by which the earth and moon have been brought into their present configuration, then similar changes must have been going on in the other bodies which make up the solar system. I will therefore make a few remarks on the other satellites and planets. In the first place it is in strict accordance with the theory, that the moon should always present the same face towards the earth. Helmholtz, was, I believe, the first who suggested tidal friction as the cause of the reduction of the moon's axial rotation to identity with her orbital motion. It is interesting to note in this connection that the telescope seems to show that the satellites of Jupiter, and one at least of the satellites of Saturn, also have the same peculiarity. The process by which tidal friction brings about the changes in the configuration of a planet and satellite is a destruction of energy (or rather its partial conversion into heat within the planet, and partial redistribution), and a transference of angular momentum from that of planetary rotation to that of orbital revolution of the two bodies about their common centre of inertia. Now a large planet has both more energy of rotation and more angular momentum; hence it is to be expected that large planets should proceed in their changes more slowly than small ones. Mars is the smallest of the planets, which are attended by satellites, and it is here alone that we find a satellite revolving faster than the planet rotates. This will also be the ultimate fate of our moon, because after the joint lunar and solar tidal friction has reduced the earth's rotation to an identity with the moon's orbital motion, the solar tidal friction will continue to reduce it still further, so that the earth will rotate faster than the moon revolves. Before, however, this can take place with us, the moon must recede to an enormous distance from the earth, and the earth must rotate in forty or fifty days instead of in twenty-four hours. But the satellites of Mars are so small, that they would only recede a very short way from the planet, before the solar tidal friction reduced the planet's rotation below the satellite's revolution. The rapid revolution of the inner satellite of Mars may then, in a sense, be considered as a memorial of the primitive rotation of the planet round its axis. The planets Jupiter and Saturn are very much larger than the earth, and here we find the planets rotating with great speed, and the satellites revolving with short periodic times. The inclinations of the orbits of Jupiter's satellites to their "proper planes are very interesting from the point of view of the present theory. The Saturnian system is much more complex than that of Jupiter, and it seems partially in an early stage of development and partially far advanced. The details of the motions of the satellites are scarcely well enough known to afford strong arguments either for or against the theory. I have not as yet investigated the case of a planet or star attended by several satellites, but perhaps future investigations may throw further light both on the case of Saturn, and on the whole solar system itself. The celebrated nebular hypothesis of Laplace and Kant supposes that a revolving nebula detached a ring, which ultimately became consolidated into a planet or satellite, and that the central portion of the nebula continued to contract, and formed the nucleus of the sun or planet. The theory now proposed is a considerable modification of this view, for it supposes that the rupture of the central body did not take place until it was partially consolidated, and had attained nearly its present dimensions. I do not pretend, in these remarks, to have thoroughly discussed the cases of the other planets, and have only drawn attention to a few salient features; in the paper itself the subject is considered at greater length. It will, however, I think, be admitted that the theory agrees with some remarkable facts in the solar system. G. H. DARWIN THE SEXUAL COLOURS OF CERTAIN DR. R. SCHULTE, of Fürstenwalde, has called my attention to the beautiful colours which appear on all four wings of a butterfly, the Diadema bolina, when looked at from one point of view. The two sexes of this butterfly differ widely in colour. The wings of the male, when viewed from behind, are black with six marks of pure white, and they present an elegant appearance; but when viewed in front, in which position, as Dr. Schulte remarks, the male would be seen by the female when approaching her, the white marks are surrounded by a halo of beautiful blue. Mr. Butler, also showed me in the British Museum an analogous and more striking case in the genus Apatura, in which the sexes likewise differ in colour, and in the males the most magnificent green and blue tints are visible only to a person standing in front. Again with Ornithoptera the hind wings of the male are in several species of a fine golden yellow, but only when viewed in front; this holds good with O. magellanus but here we have a partial exception, as was pointed out to me by Mr. Butler, for the hind wings when viewed from behind change from a golden tint into a pale iridescent blue. Whether this latter colour has any special meaning could be discovered only by some one observing the behaviour of the male in its native home. Butterflies when at rest close their wings, and their lower surfaces, which are often obscurely tinted, can then alone be seen; and this it is generally admitted, serves as a protection. But the males, when courting the females, alternately depress and raise their wings, thus displaying the brilliantly coloured upper surface; and it seems the natural inference that they act in this manner in order to charm or excite the females. In the cases above described this inference is rendered much more probable, as the full beauty of the male can be seen by the female only when he advances towards her. We are thus reminded of the elaborate and diversified manner in which the males of many birds, for instance the peacock, argus pheasant, &c., display their wonderful plumage to the greatest advantage before their unadorned friends. and here it seems hardly possible that the habit could have been consciously acquired just after birth without any experience. But if those young birds which remained motionless when frightened, were oftener preserved from beasts of prey than those which tried to escape, the habit of squatting might have been acquired without any consciousness on the part of the young birds. This reasoning applies with special force to some young wading and water birds, the old of which do not conceal themselves when in danger. Again a hen partridge when there is danger flies a short distance from her young ones and leaves them closely squatted; she then flutters along the ground as if crippled, in the wonderful manner which is familiar to almost every one; but differently from a really wounded bird, she makes herself conspicuous. Now i is more than doubtful whether any bird ever existed with sufficient intellect to think that if she imitated the actions of an injured bird she would draw away a dog or other enemy from her young ones; for this presupposes that she had observed such actions in an injured comrade and knew that they would tempt an enemy to pursuit. Many naturalists now admit that, for instance, the hinge of a shell has been formed by the preservation and inheritance of successive useful variations, the individuals with a somewhat better constructed shell being preserved in greater numbers than those with a less well constructed one; and why should not beneficial variations in the inherited actions of a partridge be preserved in like manner, without any thought or conscious intention on her part any more than on the part of the mullusc, the hinge of whose shell has been modified and improved independently of consciousness. CHARLES DARWIN Down, December 16, 1879 NOTES WE are much pleased to be able to announce that the Com. mittee of the British Association for the Exploration of Socotra have secured the services of Dr. I. B. Balfour, Professor of Botany at Glasgow, as naturalist. Besides many other qualifications for the post Dr. Balfour has recently taken part in the execution of a similar piece of work as one of the naturalists attached to the station for the observation of the Transit of Venus at Rodriguez. Dr. Balfour will leave for Aden on the 9th inst., and proceed thence to Socotra. M. PERRIER, the head of the French Survey, has been appointed a Member of the Academy of Sciences. It may be remembered that M. Perrier is a commander on the staff, and has just accomplished one of the greatest geodetic feats on record, the connection of the South of Spain with the Algerian province of Oran. M. Perrier is a supporter of M. Roudaire's scheme, and his appointment is considered likely to accelerate the work of the survey for the great Saharan Railway. WE are pleased to see that a movement is on foot to erect an educational natural history museum in Perth, as a memorial to the late Sir Thomas Moncrieffe, president of the Perthshire Natural History Society. From a statement sent us by Dr. Buchanan White, we notice that the organisers have a rational idea of what such an institution should be, and their scheme is a com The consideration of these cases leads me to add a few remarks on how far consciousness necessarily comes into play in the first acquirement of certain instincts, including sexual display; for as all the males of the same species behave in the same manner whilst courting the female, we may infer that the display is at least now instinctive. Most naturalists appear to believe that every instinct was at first consciously performed; but this seems to me an erroneous conclusion in many cases, though true in others. Birds, when variously excited, assume strange prehensive one, having in view the education of the citizens of attitudes and ruffle their feathers; and if the erection of the ancient burgh, as well as the collection of objects of natural the feathers in some particular manner were advan-history connected with the county. A generous citizen of Perth, tageous to a male whilst courting the female, there does Mr. Robert Pullar, offers 500/. of the 2,000l. which it is estinot seem to be any improbability in the offspring which in- mated the building will cost. herited this action being favoured; and we know that odd tricks and new gestures performed unconsciously are often inherited by man. We may take a different case (which I believe has been already advanced by some one), that of young ground birds which squat and hide themselves when in danger immediately after emerging from the egg ; M. E. LEVASSEUR, a well-known French geographer, has invented an amusing and instructive geographical game, to which he gives the name of "Tour du Monde." It is played on a large terrestrial globe divided into 232 spherical rectangles, each of which has a number, corresponding to a number on a list, indicating gains or losses, in accordance with the nature of the rectangle to which it belongs. The game is played with eighteen flags corresponding to the principal States of the world, from China, the most populous, down to Holland, the least populous. A brass slip, from pole to pole, contains eighteen holes, into which the flags are successively placed by the players at each revolution, commencing at the south pole and moving northwards. The gains and losses correspond with the nature of the facts indicated in the space above which a flag may stand when the globe stops revolving. Thus London counts thirty, Paris twenty, and so on, according to population. A coal-mine, a Manchester cotton factory, a grain centre, all count for gains; while meeting a Zulu or a lion in Africa, a storm in Atlantic or Pacific, a crocodile in the Nile, being caught in the Polar ice, &c., count for losses. Thus it will be seen, the new game is calculated to afford considerable excitement as well as instruction. DR. B. W. RICHARDSON has been re-elected Assessor of the University Council of St. Andrew's University. This will be Dr. Richardson's third term of office. WE last week referred to the new appointment to the RegistrarGeneral hip and the resignation of Dr. Farr. The following is Dr. Farr's dignified and temperate letter to Major Graham, the retiring Registrar-General :-"December 23.-Sir,-Having now heard from you that Sir Brydges Henniker is to be the new Registrar-General, and thus having lost all chance of being your successor, I shall be glad if the Lords of Her Majesty's Treasury will allow me to resign my appointment, and will grant me superannuation allowance to the extent of my full pay. I have served under you nearly forty years, I have taken with you three censuses, and I feel confident that I can leave my case in your hands. (Signed) William Farr." The Government has possibly a complete justification to give for the appointment of Sir Brydges Henniker; if so, they should lose no time in making it public, as their treatment of Dr. Farr has roused universal indignation. MR. EDISON publishes through the columns of the New York Herald, an elaborate and detailed account of his labours with his new form of electric lighting. Minutely describing the course of his studies, Mr. Edison says that he has made the discovery that the carbon framework of a small piece of paper is the best substance for incandescent lighting. A piece of cardboard, known in the trade as "Bristol," is cut, with a suitable punch, into strips in the form of miniature horseshoes, about 2 inches long, and one-eighth wide. A number of these strips are placed in a wrought-iron mould, separated from each other by tissue paper. The mould, after being well covered, is placed in an oven, where it is gradually exposed to a temperature of about 6c0° F., so as to allow the volatile portions of the paper to pass away. The mould is then removed to a furnace, kept there till it retains almost a white heat, and subsequently allowed gradually to cool down. On opening the mould, the charred remains of the cardboard must be taken out with great care, in order to prevent them from falling to pieces. They are placed in a small globe and attached to the wires connecting the generating machine. The next thing is to extract the air, by means of the pump, from the globe; that being accomplished, the globe is sealed, and the lamp is ready for use. It should be observed that the new lamp requires no complex regulating apparatus, such as characterised the earlier efforts. In fact, Mr. Edison finds that all previous labour in regard to regulators was practically wasted, and furthermore, that electricity can be regulated with absolute reliability in a manner precisely similar to that in which the pressure of gas is now produced. The system now adopted by Mr. Edison in connecting the wires admits of a given number of lights being extinguished without affecting those of other Lurners. In the same way as we would shut a certain number of gas burners and permit others to draw a supply from the meter, the electric light can be obtained or shut out. From the description now given it appears that the apparatus primarily used by Mr. Edison was in the shape of a large tuning-fork, constructed in a manner that both ends would vibrate when placed near the poles of the great magnetExperience has demonstrated the impracticability of that apparatus, and it became necessary to search for other means. One experiment was made after another, which had the tendency to lead gradually to the adoption of the system now employed in the generating machine, and which Mr. Edison terms the Faradaic machine. It is briefly described thus:-Two upright iron columns 3 feet in height, and 8 inches in diameter, covered with coarse wire and resting upon a base, form the magnetic poles. Fixed on an angle, so as to admit a free revolution between the poles, is a cylindrical armature of wood, wound parallel to its axes with fine iron wire. This cylinder is made to revolve rapidly between the magnetic poles, and by means of a belt, driven by an engine, strong currents of electricity are generated in the wire surrounding the armature, and these currents are carried along the wires to the electric lamp. A CHANGE has taken place in the French Ministry, and M. Freycinet, the Minister of Public Works, has been created Prime Minister by the President of the Republic. M. Varoy and General Farre, two pupils of the Polytechnic School, have been appointed to the Department of Public Works and War Office. It is known that M. Freycinet was educated in the same institution, which has never, since it was created in 1798, given at once so many Ministers to France. IN the Annual Report of the Royal Botanical Garden at Calcutta for the year 1878-79, Dr. King confirms the opinion he has expressed in former reports regarding the unsuitability of the Para rubber plants for acclimatisation in some parts of India. He acknowledges that plants may be coaxed into growing in conservatories, but considers the species far too thoroughly tropical to withstand without protection the vicissitudes of the climate of Northern India. He says, "I believe it is useless to try it anywhere in India except in the south of Burmah or the Andamans, or perhaps in Malabar. Contrary to the experience with Para rubber, the Ceara Kina (Manihot glaziovii) promises well, and if the quality of rubber yielded by it in India proves to be good, its introduction will no doubt turn out of much importance. Seeds of a species of Landolphia yielding African rubber have been received at Calcutta from Zanzibar. Dr. King reports upon them as not looking very promising, but thought possibly some of them might grow. Seeds of the mahogany tree have been received at Calcutta in large quantities, and a large number of seedlings have been distributed. The cultivation of this valuable timber tree has been taken up by the Forest Depart ment in the Government Plantation near Chittagong. quantities, also, of the seed and seedlings of the Pithecolobium saman, or rain-tree, have been distributed; and as the plant grows rapidly and seems to flower and seed freely, it may prove a valuable introduction to India. Large THE annual prize of 25,000 francs (1,000l.), given by the King of the Belgians for works of a scientific character, is now offered for the year 1881. It will be awarded to the author of the best work on the means of improving sea-ports situated upon low and sandy coasts, such as the Belgian ports. Foreigners as well as Belgian subjects may compete, as the competition is an international one. The works must be sent to the "Ministère de l'Intérieur," at Brussels, before January I next. The prize will be awarded by a jury composed of four foreigners and three Belgians, all of whom are nominated by his Majesty. A PRIZE is offered by the Governor of the Prussian province of Saxony for the best text-book of natural science and agricul |