diminished their consumption of imported commodities. The increase of £478,681, as shown above, has, therefore, overstocked our markets. The articles which chiefly make up this increase are all subject to the new duties imposed by the present tariff, and the increase of £447,109 which the figures exhibit must be very bewildering and disappointing to those politicians who imposed the duties for the purpose of restricting importations and encouraging local industries. With reference to our export trade, it appears that contemporaneously with the increase in imports there was a considerable diminution in the value of exports. The decline of wool last year was somewhat compensated for by a material increase in other products of our pastoral industry-viz., tallow, skins, leather, bonedust, and preserved meats, the last-named article contributing £80,835 to the value of export, as compared with £28,565 the previous year." ADDENDA III. (From the Times.) The following extract, relating to the state of the labour-market, is from the Argus of April 23rd. It disposes of the foolish and selfish "mechanic cry" raised from time to time here against the continuance of assisted immigration: THE LABOUR MARKET. "The long-continued drought having now fairly broken up, farming operations have been resumed with great activity throughout the country, and there has been a corresponding demand created for farm labourers. All descriptions of tradesmen are able to obtain full work at the current rate of wages. In many parts of the country the rates rule higher than those quoted. On one Government contract the bricklayers employed were receiving 12s. per day, and an attempt was made to extort 14s. per day by means of a strike. For domestic servants the demand is as great and as badly supplied as ever. Since last mail, the immigrant ship Percy has arrived with 366 passengers; but, owing to sickness on board, the vessel has been detained at the quarantine ground. As most of these passengers will go to their friends, the market will be but slightly relieved." all of them by the lecturer at the time he was de-energy represented by 64. Hence we see that by WHAT IS ENERGY ?* IN TWO PARTS.-PART II. Here, then, we have no annihilation of energy, but merely the transformation of it from actual energy into that implied by position; nor have we any creation of energy when the stone is on its downward flight, but merely the re-transformation of the energy of position into the original form of actual energy. We shall presently discuss what becomes of this actual energy after the stone has struck the ground; but in the meantime we would repeat our remark how intimate is the analogy between the physical and the social world. In both cases we have actual that in the social it is impossible to N our first article it was shown that energy, or energy and energy of position, the only difference energy due to actual motion, and that due to posi-measure energy with exactness, while in the me tion. We ended by supposing that a stone shot chanical world we can gauge it with the utmost pre vertically upwards had been caught at the summit cision. of its flight and lodged on the top of a house; and this gave rise to the question, What has become of the energy of the stone? To answer this we must learn to regard energy, not as a quality, but rather as a thing. The chemist has always taught us to regard quantity or mass of matter as unchangeable, so that amid the many bewildering transformations ON Monday, July 4th, a large gathering of of form and quality which take place in the chemical chosen the force of gravity, acting upon a stone shot world, we can always consult our balance with a certainty that it will not play us false. But now the physical philosopher steps in and tells us that energy is quite as unchangeable as mass, and that the conservation of both is equally complete. There is, however, this difference between the two things-the same particle of matter will always retains the same mass, but it will not always retain the same energy. As a whole, energy is invariable, but it is always shifting about from particle to particle, and it is hence more difficult to grasp the conception of an invariability of energy than of an invariability of mass. For instance, the mass of our luminary always remains the same, but its energy is always getting less. And now to return to our question,-What has become of the energy of the stone? Has this disappeared? Far from it; the energy with which the stone began its flight has no more disappeared from the universe of energy, than the coal, when we have burned it in our fire, disappears from the universe of matter. But this has taken place:-the energy has changed its form and become spent, or has disappeared as energy of actual motion, in gaining for the stone a position of advantage with regard to the force of gravity. the medical profession, numbering very nearly 2,000, and embracing the elite of the metropolitan and surburban practitioners and some distinguished foreign visitors, assembled at the invitation of one of their fraternity, at the Royal Polytechnic Institution, to witness the trial of a new mode of conveying practical instruction in a department of surgery which has long been considered as one of the opprobria medicine. For some time past efforts have been made to improve in various ways the means of imparting clinical information, as distinguished from mere book-knowledge, to the students of medicine in this country. The University of London has of late taken the lead amongst examining bodies, by requiring of its graduates in medicine that they should pass a practical examination, in addition to the previous theoretical examination, in order to obtain its much-coveted degrees; and the late Sir James Clark was a steadfast advocate of the necessity of improvement in this most important branch of medical education. The large theatre and effective optical apparatns of the Institution having been placed for this purpose by the directors at the disposal of the profession, Dr. Balmanno Squire proceeded to demonstrate to his audience some of the more important cases of cutaneous disease that had lately occurred in the practice of the British Hospital for Diseases of the Skin in Great Marlborough-street, and also in Finsbury square, of which institution Dr. Squire is one of the honorary surgeons. The room having been darkened, magnified images of the patients themselves were thrown, considerably larger than life-size, on the spacious screen of the theatre, by means of the dissolving-view apparatus, so that all the details of the various eruptions were plainly visible even from the most distant parts of the theatre. Dr. Balmanno Squire, after given a résumé of the acknow-which it had at first. ledged difficulties of imparting a practical knowledge Let us now revert for a moment to the definition of the medical art to students, proceeded to show how the method he submitted would dispose at least of the more serious of these difficulties, and explained that it was not only applicable to the department of practice that he himself followed, but was capable of wide extension to the subject of medical education generally. Students of medicine at every hospital persisted in flocking round the most popular teacher; consequently, but a few could get anything like a satisfactory view of the patient concerning whose case instruction was being given. Again, it was by no means an easy thing, even at our largest hospitals, to find within a limited space of time a sufficient variety of illustrative cases to enable the members of any given class to go forth from the hospital with a comprehensive practical knowledge of the subject treated. The plau he proposed would, by magnifying the object to be demonstrated, enable every detail to be seen by every member of a large class, and to be pointed out to If we study this particular instance more minutely, we shall see that during the upward flight of the stone its energy of actual motion becomes gradually changed into energy of position, while the reverse will take place during its downward flight if we now suppose it dislodged from the top of the house. In this latter case the energy of position with which it begins its downward flight is gradually reconverted into energy of actual motion, until at last, when the stone reaches the ground, it has the same amount of velocity, and therefore of actual energy, of energy, which means the power of doing work, and we shall see at once how we may gauge munerically the quantity of energy which the stone possesses; and in order to simplify matters, let us suppose that this stone weighs exactly one pound. If therefore, it has velocity enough to carry it up one foot, it may be said to have energy enough to do one unit of work, inasmuch as we have defined one pound raised one foot high to be one unit of work; and in like manner if it has velocity sufficient to carry it 16ft. high, it may be said to have an energy equivalent to 16 units of work or foot-pounds, as those units are sometimes called. Now, if the stone be discharged upwards with an initial velocity of 32ft. per second, it will rise to 16ft. high, and it has therefore an energy represented by 16. its initial velocity be 64ft. per second it will rise 64ft. high before it turns, and will therefore have By BALFOUR STEWART, in Nature. But if Protens-like, this element energy is always changing its form; and hence arises the extreme difficulty of the subject; for we cannot easily retain a sufficient grasp of the ever-changing element to argue experimentally regarding it. All the varieties of physical energy may, however, be embraced under the two heads already mentioned, namely, energy of actual motion and of position. We have up into the air, as our example; but there are other forces besides gravity. Thus, a watch newly wound up is in a condition of visible advantage with respect to the force of the main-spring; and as it continues to go it gradually loses this energy of position, converting it into energy of motion. A crossbow bent is likewise in a position of advantage with respect to the spring of the bow; and when its bolt is discharged, this energy of position is converted into that of motion. Thus again, a meteor, a railway train, a mountain torrent, the wind, all represent energy of actual visible motion; while a head of water may be classed along with a stone at the top of a house as representing energy of position. The list which represents visible energy of motion and of position might be extended indefinitely; but we must remember that there are also invisible molecular ruotions, which do not the less exist because they are invisible. One of the best known of these molecular energies is radiant light and heat-a species which can traverse space with the enormous velocity of 186,000 miles a second. Although itself eminently silent and gentle in its action, it is nevertheless the parent of most of the work which is done in the world, as we shall presently see when we proceed to another division of our subject. In the mean time we may state that radiant light and heat are supposed to consist of a certain undulatory motion traversing an ethereal medium which pervades all space. Now, when this radiant energy falls upon a substauce, part of it is absorbed, and in the process of absorption is converted into ordinary heat. The undulatory motion which had previously traversed the thin ether of space has now become linked with gross palpable matter, and manifests itself in a motion which it produces in the particles of this matter. The violence of this rotatory or vortex-like motion will thus form a measure of the heat which the matter contains. Another species of molecular energy consists of electricity in motion. When an electric current is moving along a wire, we have therein the progress of a power moving like light with enormous velocity, and, like light, silent in its operation. Silent, we say, if it meets with no resistance, but exceedingly formidable if it be opposed; for the awe-inspiring flash is not so much the electricity itself as the visible punishment which it has inflicted on the air for daring to impede its progress. Had there been a set of stout wires between the thunder-cloud and the earth, the fluid would have passed into the ground without disturbance. The molecular energies which we have now described may be imagined to represent motion of some sort not perceived by the outward eye, but present nevertheless to the eve of the understanding; they may therefore be compared to thargy of a body in visible motion, or actual energy, as we have There is finally a species of molecular energy caused by chemical separation. When we carry a stone to the top of a cliff, we violently separate two bodies that attract one another, and these two bodies are the earth and the stone. In like manner when we decompose carbonic acid gas into its constituents we violently separate two bodies that attract one another, and these are carbon and oxygen. When, therefore, we have obtained in a separate state two bodies, the atoms of which are prepared to rush together and combine with one another, we have at the same time obtained a kind of energy of molecular position analogous on the small scale to the energy of a stone resting upon the top of a house, or on the edge of a cliff on the large or cosmical scale. MOTIVE POWER FROM DEEP WELLS. the ground, through the thousands of tubes in the sent by post in the United Kingdom at the follow- It has been demonstrated that every square inch of leaf lifts three five-hundredths of an ounce every twenty-four hours. Now, a large forest tree has about five acres of foliage, or six million two hundred and seventy-two thousand six hundred and forty square inches. This being multiplied by three five-hundredths (the amount pumped by every inch) gives us the result-two thousand three hundred and fifty-two ounces, or one thousand one hundred and seventy-six quarts, or two hundred and ninetyfour gallons, or eight barrels. A medium sized forest tree, about five barrels. The trees on an acre give eight hundred barrels in twenty-four hours. An acre of grass, or clover, or grain, would yield about the same result. The leaf is a worker, too, in another field of labour, where we seldom look-where it exhibits its unselfishness-where it works for the good of man in Tto the top of country mansions, by utilizing a most wonderful manner. It carries immense the power of a neighbouring stream, has already scends into the hydraulic ram through a conduit. THE LEAF AS A WORKER. says, R. J. S. SEWALL, in the American Entomolo Digist leaf as a worker. Let us learn what it does, and how it does it. In the first place, let us fully understand what we mean by worker-or let us agree as to the definition of the term. To illustrate, we say of the locomotive, that it performs a certain amount of labour, it turns so many wheels, drives so many and from the clouds to the earth. Rather dangerous CARMINE. THIS beautiful red pigment is obtained from the cochineal insects, which were natives of Mexico originally, but are now raised with success in many other countries, and particularly in India, Spain, and Algeria. They feed upon the Nopal cactus or prickly pear, on which the females fix themselves, being wingless, and from which they never move. At a certain time in the year they are gathered from the pear by means of a brush, and they are then plunged in hot water and exposed in the sun to dry. When dried they have the appearance small berries of puce of sulour, and in this state they for the It cochineal of commerce, and are exported to this and other countries for making carmine. takes 70,000 of the dried cochineals to weigh a pound. Carmine is the most brilliant of all red colours, but its beauty depends materially upon the method first prepared by a of manufacturing. It was Franciscan monk at Pisa, who discovered it accidentally while compounding medicines containing cochineal, and in 1656 it began to be manufactured. A great many experiments have been made to extrials have proved this to be a most delicate operatract it in a state of absolute purity, but repeated tion, and one requiring great skill, as well as very careful attention. There are several modes of manufacturing it. One process is to digest 1lb. of cochineal in 3 gallons As we rub a stick of sealing-wax or a glass tube of water for fifteen minutes; then add 1 ounce of with a warm silk handkerchief, so the air is always cream of tartar; heat gently for ten minutes; add rubbing over the face of the earth with greater or half an ounce of alum; boil for two or three less rapidity. And what a huge electrical machine! Ininutes; and, after allowing the impurities to But be not afraid, the leaf will see that it is taken settle, the clear liquid is placed in clean glass pans, care of. As we guard our roofs from the destruc- when the carmine is slowly deposited. After a time tive action of lightning-dashing to the earththe liquid is drained off, and the carmine dried in crashing, rending, burning on its way-by erecting the shade. Roret, in his well-known encyclopædia the lightning rod, whose bristling points quietly of colours, gives the following as an old method: drain the clouds, or failing to do this, receive the 20 grammes (310 grains) of cochineal, 2 grammes charge and bear it harmless to the earth- -so God of the seed of chouan, an Oriental tree, 10 grammes has made a living conductor in every pointed leaf, of the bark of the autour, another Oriental tree, in every blade of grass. It is said that a common and 1 gramme of alum are pulverized, each in a blade of grass, pointed by nature's exquisite work- separate mortar. 2 litres (2 quarts) of very manship, is three times as effectual as the finest clear river or rain water is made boiling in a clean cambric needle; and a single twig of leaves is far vessel. When it boils, the chouan is thrown into the more efficient than the metallic point of the best vessel, and after boiling very fast the liquid is of a single ferest in disarming the forces of the another well cleansed vessel. constructed rod. What, then, must be the agency poured cautiously through fine white linen into This liquid is ning, and it furnishes the lightning rods. Take a hint, then, and plant trees. to boil, and when it commences, boiling the cochineal is added; next autour, and at last the alum, at which moment the vessel is taken away from the fire. The liquid is poured into a porcelain plate, and left there for seven or eight hours in order to subside. Then the clear liquid which flows uppermost is cautiously discharged, and the sediment is exposed to the sun to dry. When dried it feather, and this very fine and very beautifully coloured powder is the carmine of cochineal. looms, draws so many cars so many miles an hour- pestage, and for other purposes relating to is gathered from the plate with a fine brush or a we speak of it as a worker. So, too, of man-we speak of him as a worker. He performs so much labour, physical or mental. Yet the locomotive, with all its penderous bars, its mysterious valves, its great levers, its hidder springs, can de nothing. It is dead, inert metal. True, too, of man-that wonderful combination of bones and muscles and nerves and tissues can do nothing, but decay, and be resolved to dust again. The brain cannot think, the eye cannot see, the ear cannot hear, the nerves cannot thrill, the muscle cannot contract. In the same sense the leaf can do nothing. Yet in the sume sense that a locomotive can draw a train, or that man can think and labour, is the leaf a labourer that outworks them all. The locomotive is a combination of material things se arranged that through or by them we discover the operations of force. Man himself is nothing more. The leaf is the same. Better, perhaps, that we say that these are the workshop wherein force exhibits itself, and produces results. When did the leaf begin its work? It was the first to rise on creation's morn and go forth to labour. Ere the almost shoreless ocean dashed upon the low Silurian plain, the leaf was at its work. And through all the long ages it has worked-worked to develop better and higher forms of life. And the earth's bread face is written all over with the evidences of its faithfulness. Now what does it do? It pumps water from THE HALFPENNY POSTAGE. In the preparation of carmine, much depends on a clear atmosphere and bright, sunny day, during the process, as the beautiful colour is in no case nearly so good when it is prepared in dull weather. This accounts in a great part for the superiority of French carmine over that made in England. Moreover, carmine cannot be made during cold weather, because in such case it will not precipitate to the bottom of the liquid, but will form into a sort of jelly, and in this condition will soon spoil. Pure carmine is very expensive, and this has led to the manufacture and sale of many substitutes. All of them are inferior, however, and for finest work only the pure article should be employed. THE SCHOOL OF MINES' SCHOLARSHIPS.-At a meeting of the Council of the Royal School of Mimes held on Saturday, July 2nd, the following awards were made:-Two Royal Scholarships of £15 each for first year's students, to W. H. Greenwood and F. C. Mifoord; H.R.H. the Duke of Cornwall's Scholarship to P. C. Gillchrist; the Royal Scholarship of £25 to R. . Atkinson; the De la Beche Medal and prize of books to W. Gowland; and the Director's Medal and prize of books to P. C. Gillchrist. The Edward Forbes Melal and prize of books were not competed for this year.. MECHANICAL MOVEMENTS.* (Continued from page 366.) Proportional compasses used in copying 209. drawings on a given larger or smaller scale. The pivot of compasses is secured in a slide which is adjustable in the longitudinal slots of legs, and capable of being secured by a set screw. The dimensions are taken between one pair of points and transferred with the other pair, and thus enlarged or diminished in proportion to the relative distances of the points from the pivot. A scale is provided on one or both legs to indicate the proportion. 210. Bisecting gauge. Of two parallel cheeks on the cross-bar one is fixed and the other adjustable and held by thumb screw. In either cheek is centred one of two short bars of equal length, united by a pivot, having a sharp point for marking. This point is always in a central position between the cheeks, whatever their distance apart, so that any parallel sided solid to which the cheeks are adjusted may be bisected from end to end by drawing the gauge along it. Solids not parallel sided may be bisected in like manner, by leaving one cheek loose, but keeping it in contact with solid. 211. Self-recording level for surveyors. Consists of a carriage, the shape of which is governed by an isosceles triangle having horizontal base. The circumference of each wheel equals the base of the triangle. A pendulum, when the instrument is on level ground, bisects the base, and when on an inclination gravitates to right or left from centre accordingly. A drum, rotated by gearing from one of the carriage wheels, carries sectionally ruled paper, upon which pencil on pendulum traces profile corresponding with that of ground travelled over. The drum can be shifted vertically to accord with any given scale, and horizontally, to avoid removal of filled paper. 212. Wheel-work in the base of capstan. Thus provided, the capstan can be used as a simple or compound machine, single or triple purchase. The drumhead and barrel rotate independently; the former, being fixed on spindle, turns it round, and when locked to barrel turns it also, forming single purchase; but when unlocked, wheel-work acts, and drumhead and barrel rotate in opposite directions, and velocities as three to one. 213. J. W. Howlett's patent adjustable frictional gearing. The upper wheel, A, shown in section, is composed of a rubber disk with V-edge, clamped between two metal plates. By screwing up the nut, B, which holds the parts together, the rubber disc is made to expand radially, and greater tractive power may be produced between the two wheels. 214. Scroll gear and sliding pinion, to produce an increasing velocity of scroll-plate, A, in one direction, and a decreasing velocity when the motion is reversed. Pinion B, moves on a feather on the shaft. 215. P. Dickson's patent device for converting an oscillating motion into intermittent circular, in either direction. Oscillating motion communicated " of strong boiler plate. By the pressure of steam, admitted at the top of this monte-jus, the juice is forced through a pipe into the defecating pans, where it is rapidly raised to about 180° Fahr., and "dosed' with milk of lime. It is then brought to the boiling point, when the scum is removed, and submitted to the action of powerful presses, for the purpose of obtaining what juice may be still contained in it. The whole of the juice is then transferred to the carbonatation pan, and carbonic acid gas forced through it. After undergoing this process it is conveyed to the filters, upright cylindrical vessels, filled with granulated bone-black, a section of one of which is seen at Fig. 1. M is a cover, fitting tightly on the top, for the purpose of introducing the bone-black. N is a man-hole for drawing out the spent bone black, and also for admitting a sieve, covered by a cloth, which is introduced into the bottom of the filter before the bone-black is admitted. S is a pipe for the introduction of steam, pure water, beet-root juice, and syrups into the filter, by means of the pipes F, E, D, C, which are in connection with S, through which the passage of either of these fluids is regulated at will, by means of special taps. The pipe S is also fitted with a small connecting pipe, L, through which the air escapes from the filter, as it gradually fills with liquid. The juice, after having traversed the whole body of bone-black in the filter from top to bottom, is not allowed to run out at the bottom through the pipes W and Y, the cock, V, being kept close, so as to force it to ascend through the upright pipe, U, whence it is allowed to flow out through the open cock, H. The juice is received in a movable funnel, T, which fits on the upright pipes, R and A. juice is being run through the filter, the funnel is placed on R, and the liquid is thus conveyed either directly to a tank or to the evaporating pans. If syrup is being passed through the filters the funnel is placed on Q, and run to the concentrating pans. V is used for running water into the pipe, Y, which earries it off as waste. After leaving the filters, the clear juice is conveyed to the evaporating pans, where it is reduced to a certain degree of consistency, "syrup," after which it has to be filtered a second time. The old-fashioned evaporating pans have given place to the "triple effect vacuum pans, a side view of which is given at Fig. 2. The three pans, or bodies, are marked I., II., III., the three intermediate vapour columns are numbered 1, 2, 3. A is the pipe which carries the juice into the first body; BC, is a pipe which carries the juice from the first body to the second, and GF another which conveys it from the second to the third body, from whence the pipe F takes it to the monte-jus; K is a pipe and valve for introducing the steam for heating into the first body; K1 is a pipe for running off condensed water; L M is a pipe for conveying spent steam and condensed water to the condenser; Qis the outlet for the hot water of condensation; P is a glass indicator for the height of the juice in the pan; R is the apparatus for sampling, in If order to learn the density of the juice; Srepresents the glass bull's eye for observing the progress of ebullition; T is a small funnel for the introduction of melted fat to arrest too violent ebullition; T1 is the small cock for admission of air; U is a thermometer indicating the temperature of the boiling juice; V is a special barometer for low pressures for determining the degree of vacuum; X is an indicator of the water accidentally collected in the columns; and Z the pipe for running it out. Fig. 3 shows a section through the last body of the apparatus represented in Fig. 2, and gives a view of the internal arrangement of a vacuum pan. The lower portion of the body, III., shows the disposition of the tubes, around which the steam for beating the juice circulates. These tubes are inserted at both extremities into the perforated end-plates. The space above the top plate is the steam or vapour chest, where the vacuum is formed, and the steam of the boiling juice collects before being carried off. N is the condenser, O its injection pipe; M the exit pipe for heated condensation water, which is drawn off by an air-pump; A is an upright pipe surrounded by an empty space, B, in which accidental water and liquid collects. The theory of the vacuum pan is very simple, being based on the fact that the juice boils, under the ordinary pressure of the atmosphere, at 212° Fahr., and as this pressure is reduced so the boiling point is proportionately lowered. Now, waste steam, with a temperature of 212° Fahr. will boil the sugar in the first pan without any vacuum, and passing to the next, in which is a partial vacuum, will boil that at a temperature say, of 190°; and finally going to the third will cause the sugar to boil at 150°, under the influence of a more perfect vacuum. Thus the concentration of the juice costs nothing for fuel, being all accomplished by the exhaust steam. The syrup, after being boiled and filtered till it reaches the proper consistency, is distributed into a number of crystallizers, and left quiet in a room the temperature of which is kept at 95° Fahr. When crystallization has taken place the contents of the crystallizers are emptied into centrifugal turbines, the outer surface of which is covered with metallic tissue, through the meshes of which the syrups flow, by the action of the centrifugal force, while the crystals of sugar are retained within. In a very short time the sugar may be scooped out of from the inside of the centrifugal, and after being broken up in a lump-breaking" machine and passed through a screen it is ready for market. 66 THE MANUFACTURE OF CHLOROFORM.-Accord ing to the late Jas. Y. Simpson, there is a single manufactory of chloroform, located in Edinburgh, which makes as many as eight thousand doses a day, or between two millions and three millions of doses every year-evidence to what an extent the practice is now carried of wrapping men, women, and children in a painless sleep during some of the most trying moments and hours of human existence. N ON ZYMOTICS.* to the Registrar-General's first O for the last ten years, we find that in England only to show how little is really known about the. The state from the town just mentioned, and bere The oxide of tin and Wales about 500,000 people die every year; of which 500,000, 100,000 die of zymotic diseases; that is, 20 out of every 100 people who die, die, usually at an early age, of disease which can and ought to be prevented. These so-called zymotic diseases have been chosen for the subject of this article, because, they best illustrate what has been said about the prevention and the cure of disease. No approach to any means of curing them has been discovered; but of all the complaints known, they are the most easily preventable; in no other group of diseases is of any support from the manner in which these copper lodes are met with in the "killas" or Lower there a something which can almost be handled which is the essence of the complaint, without which the complaint would not exist. It is to the destruction of this substance that our efforts in the suppression of these diseases are directed; for could all the contagious material in the universe be destroyed, these diseases would cease to have a place in the nosology. A knowledge of their natural history is necessary to a comprehension of the means to be employed in preventing their occurrence, and a slight sketch will therefore be given of their course when attacking the individual, and of the circumstances under which they spread. vances, supports this view. The zymotic theory From the little town of Calstock a very large quantity Devonian rock, while tin ore is found only when In this district mines are descended by means of vertical ladders placed in short shafts or "winzes" connecting the "levels" which are worked at regular dis tances below each other. One of these mines, worked to a depth of upwards of 400ft. below the Tamar, was explored by the author, and the description of the mine and mode of working out the lode concluded the paper. The diseases called zymotic-a name which is bad, because based upon a false theory, but which has become sanctioned from long use-are, in systematic medicine, known as the acute specific diseases; acute, because always of short duration, together, predispose to the reception of these genera and families of Fossil Brachiopoda in British tending spontaneously to cease at a fixed date from the attack, and never extending over months and years like chronic diseases; specific, because they are accompanied by a process peculiar to each one of the group, a process quite sui generis, and unknown in the course of other acute complaints. Amongst them stand measles, scarlet fever, hooping cough, diphtheria, mumps, typhoid fever, typhus fever, and small pox. Measles may be regarded as a type of this class of complaints. It has a greater tendency to spare the life of the individual than most of the others; it is very widely distributed, and few people reach adult age without having suffered from an attack. The history of the complaint, and of those associated to it, is therefore personally interesting to almost every one. The acute specific diseases are distinguished by five peculiarities. 1. They occur but once in the life of an individual, who thenceforth is secured from a second attack. 2. They always result from contagion or infection, never arising de novo from exposure to cold, or other causes of disease, as bronchitis or rheumatism does. 3. There is always an interval, longer or shorter, between the date when the individual receives the contagion into his system, and the date when he first begins to feel ill. 4. There is an interval between the first feelings of illness and the first appearance of the specific process, the rash on the skin, or the sore throat. 5. The specific disease always runs a sharp well-defined course lasting a certain number of days, and tending to end in the recovery of the patient, at the termination of the specific process. These five characters will now be considered more in detail. Each disease, as a general rule-and only as a general rule-occurs but once during life. Every mother, for example, knows that when her child has had the measles, or the hooping cough, it will be secure against a second attack. It not unfrequently happens, however, that a second attack of measles or small-pox occurs; in these cases, especially the latter, the complaint runs a much less severe course than in the first. In the great majority of individuals, the protection afforded by one of this group of diseases against its recurrence is complete. This immunity from a second attack is one of the most curious problems in medicine. Everyone knows how a part, once affected with a complaint, is liable to a return on the slightest causes, e. g. a common cold, or a sore throat. With the acute specific, or zymotic diseases, the case is exactly the reverse; and at the present moment there is of this no satisfactory explanation whatever. THE ECONOMICAL PURIFICATION OF COAL GAS. In the second paper Mr. Lobley gave the results of an investigation into the range and distribution of the embodying the results arrived at, and intended to show strata, and exhibited a series of diagrammatic tables by a peculiar arrangement the increment, decrement, and maximum development of each genus and family. The genera and families were arranged in the order of their incoming or earliest appearance in Briti strata, and every species occurring in each geological formation was separately and distinctly indicated. number of species indicated in the tables and catalogued in the lists accompanying the paper was upwards of eight hundred. A great number of these are, however, recurrent species. The On the conclusion of the paper, which was of too de tailed and technical a character to be condensed with success, Mr. Henry Woodward, F.Z.S., pointed ont the difficulty that exists in assigning to the genus Calceola its true zoological place. The presence of a so-called operculum seems to be an insuperable objection to this remarkable genus being included in the Colenterata. Mr. Woodward expressed his opinion that it was probable further research will lead to the conclusion that Calceola is allied to the Hippartida. Professor J. Rupert Jones said the tables would have been more complete had they embraced the results of foreign as well as British research, the area of these islands being too small for satisfactory conclusions respecting the life of any one geological epoch to be drawn from a study of British fossils merely. MR. F. C. HILLS, of Deptford, makes the am- SCIENTIFIC SOCIETIES. GEOLOGISTS' ASSOCIATION. Mr. Lobley replied to the objections that had been made, and the chairman, after paying a well merited tribute of praise to the great work on the Brachiopoda by Mr. Davidson, concluded the proceedings by urging the members of the association to take advantage of the facilities afforded by the railways for visiting interesting geological localities, and to record their observations in such papers as the former of the two that had been read that evening. He called for a vote of thanks to the author of the two papers, and the meeting separated. This was the concluding meeting of the session 1869–70. TRACTION.-Mr. A. Thomas says:-"It is stated that the resistance to draught on a well macadamised road is about 661b. tothe ton, on a good granite pavement 831b. to the ton and on a rail about 8lb. to the ton. Now, of course, these figures are calculated for a dead level, a very small gradient altering the proportion which they bear to each other altogether, and this leads me to ask some of your correspondents to inform me whether where the tramways. Does not this want of bite make it harder work for horses to draw a load up hill on a tramway than on a macadamised road?" At the meeting of this association, held at University roads are hilly any advantage results from the use of Another striking feature in the natural history of these disorders is that they are never known to arise spontaneously, as other complaints do; but their origin is always due to a certain contagious matter. There is no properly authenticated case on record of a person having suffered from an acute Specific disease without having been in some way infected from another person suffering from the same complaint. Recent discoveries seem to suggest that this contagious matter is a vegetabletion of the British Fossil Brachiopoda." growth-a fungus. Some observers, especially in Germany, aver that they have been enabled to detect under the microscope the little plant which is the cause of cholera; others assert, that certain fungi found in mouldy straw will produce measles in less than forty-eight hours after inoculation. Sir Henry Holland has thrown out the idea that these diseases are produced by clouds of animalcules passing over a country; and he considers that the way in which an epidemic or contagious fever ad College on Friday the 1st July, Professor "Two Days in a Mining District,' * Written by J. Wickham Legg, M.D., and extracted from The Student. mine. FOWLS v. WORMS.-M. Giot, a French Entomologist, has lately found new employment for fowls. He says that French farmers have, during the past year, Adam Murray, Esq., F.G.S., exhibited a collection of complained bitterly of the prevalence of worms, which infest corn and other crops, the highest cultivated specimens of ores and other minerals from East Corn-fields being the most infested. Fowls are known to be wall, as well as : plan and section of a copper- the most indefatigable worm destroyers, pursuing their prey with extraordinary instinet and tenacity. But The first paper contained an account of a brief visit fowls cannot conveniently be kept upon every field, nor paid to the mining district of east Cornwall, in which are they wanted there at all seasons. Therefore M. The Giot has invented a perambulating fowl-house, which is both copper and tin mines are very numerous. author dwelt with evident pleasure on the beautiful described as follows: "He has large omnibuses, fitted scenery of the river Tamar, which meanders through the up with perches above, the nest beneath. The fowls are shut in at night, and the vehicle is drawn to the required richly wooded valleys on the eastern side of this spot, and, the doors being opened every morning, the district, to which the river is of very great service, as it fowls are let out to feed during the day in the fields. facilitates the conveyance of the orcs to the localities Knowing their habitation, they enter it at nightfall withwhere they are smelted. out hesitation, roost and lay their eggs there. |