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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. reference to our export trade, it appears that contem poraneously 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 exports, 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."

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all of them by the lecturer at the time he was describing it. By the method proposed, the patient might be instantaneously photographed before either the natural progress of his disease or its amelioration under the resources of art had impaired its utility as a means of conveying instruction; and at the same time in cases where colour formed an important feature of it, this could be added to the photograph itself by an expert artist, working under the eye of the teacher himself. In the case of cutaneous disease-the most difficult of all subjects to illustrate by these means-colour was certainly a most important feature. But he appealed to those he saw around him, many of whom he knew to be well versed in this special subject, whether the illustrations he had brought before them were not in colour as well as in form and shadow sufficiently life-like to afford a lecturer ample opportunity for pointing out to a class of students all the essential peculiarities of each disease, and to enable those students when they entered upon private practice to recognize at once the nature of similar cases whenever they might meet with them. He trusted to see at the next medical session this important aid to tuition, as he would take leave to call it, utilized at all of our great medical schools, not only in the matter of cutaneous diseases, which might be taken as a crowning test of its efficacy, but also in the matter of tumours, dislocations, deformities, fractures, characteristic alterations of the countenance, and in short, all occasions to which this process is applicable.

WHAT IS ENERGY?*

IN TWO PARTS.-PART II.

than

energy represented by 64. Hence we see that by doubling the velocity the energy is quadrupled, and we might show that by tripling the velocity the energy is increased nine times. This is expressed in general terms by saying that the energy quantity of work which a moving body can accom plish varies as the square of its velocity. This fact is well known to artillerymen, for a ball with a double velocity will penetrate much more twice as far into an obstacle opposing its progress. Let us now take the stone or pound weight, baying an initial velocity of 64ft. per second, and consider the state of things at the precise moment whea it is 48ft. high. It will at that moment have as actual velocity of 32ft. per second, which, as e have seen, will represent 16 units of work. started from the ground with 64 units of work in it What, therefore, has become of the difference→ 48 units? Evidently it has disappeared as acta energy; but the stone, being 48ft. high, has a energy of position represented by 48 units; so the at this precise moment of its flight its actual energy (16) plus its energy of position (48), are together equal to the whole energy with which it started (64).

Bat s

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

N our first article it was shown that energy, or energy and energy of position, the only difference

that in the social

it

is

to 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.

of

The chemist has always taught us to regard quantity or mass of matter as unchangeable, so that amid the many bewildering transformations of form and quality which take place in the chemical 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.

MEDICAL EXPERIMENT. On the medical professio of Monday, July 4th, a large gathering of nearly 2,000, and embracing the élite 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 apparatus 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 If we study this particular instance more minutely, the British Hospital for Diseases of the Skin in we shall see that during the upward flight of the Great Marlborough-street, and also in Finsbury-stone its energy of actual motion becomes gradually square, of which institution Dr. Squire is one of the changed into energy of position, while the reverse honorary surgeons. The room having been dark- will take place during its downward flight if we ened, magnified images of the patients themselves now suppose it dislodged from the top of the house. were thrown, considerably larger than life-size, on In this latter case the energy of position with which the spacious screen of the theatre, by means of the it begins its downward flight is gradnally recondissolving-view apparatus, so that all the details of verted into energy of actual motion, until at last, the various eruptions were plainly visible even from when the stone reaches the ground, it has the same the most distant parts of the theatre. Dr. Bal- amount of velocity, and therefore of actual energy, mauno Squire, after given a résumé of the acknow- which it had at first. ledged difficulties of imparting a practical knowledge 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 plan 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

Let us now revert for a moment to the definition of energy, which means the power of doing work, and we shall see at once how we may gauge numerically 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. But if its initial velocity be 61ft. per second it will rise 64ft. high before it turus, and will therefore have

By BALFOUR STEWART, in Nature.

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 chosen the force of gravity, acting upon a stone shot 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 motions, 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 s 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 visi ble 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

8

in visible motion, or actual energy, as we have
termed it.
But we have also molecular energies which are
more analogous to the energy of position of a stone
at the top of a cliff.

For instance, two bodies near one another may be endowed with a species of energy of position due to opposite electrical states, in which case they have a tendency to rush' together, just as a stone at the top of a cliff has a tendency to rush to the earth. If the two bodies be allowed to rush together, this energy of position will be converted into that of visible motion, just as when the stone is allowed to drop from the cliff, its energy of position is con

verted into that of visible motion.

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 atoins 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.

the ground, through the thousands of tubes in the sent by post in the United Kingdom at the follow-
stem of the tree (the tubes which itself has made), ing rates of postage:-On a registered newspaper,
and sends it into the atmosphere in the form of not exceeding, with any supplement, and with any
unseen mist, to be condensed and fall in showers- cover, six ounces in weight, one halfpenny. On a
the very water that, were it not for the leaf, would book packet, or pattern or sample packet, if not
sink in the earth, and find its way perchance exceeding two ounces in weight, one halfpenny; if
through subterranean channels to the sea. And exceeding two ounces in weight, for every additional
thus it is that we see it works to give us the "early two ounces, or fractional part of two ounces, one
and the latter rain." It works to send the rills and halfpenny. On a post card, one halfpenny. The
streams, like lines of silver, adown the mountain Treasury may, from time to time, by Treasury
and across the plain. It works to pour down the warrant, allow any newspapers and periodical
larger brooks which turn the wheel that energizes publications, British, Colonial, and foreign, to be
machinery, which gives employment to millions. sent between the United Kingdom and places out
And thus a thousand wants are supplied-commerce of the United Kingdom, whether through the United
stimulated-wealth accumulated-and intelligence Kingdom or not, at such rates of postage not ex-
disseminated through the agency of this wealth. ceeding twopence for each newspaper or publication,
The leaf does it all.
irrespectively of any colonial or foreign postage,
and on such conditions as they think fit, and ac-
cording to Post-office regulations to be from time
to time made in that behalf.

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 MOTIVE POWER FROM DEEP WELLS. unselfishness-where it works for the good of man TH THE value of the hydraulic ram for raising water in a most wonderful manner. It carries immense to the top of country mansions, by utilizing quantities of electricity from the earth to the clouds, the power of a neighbouring stream, has already and from the clouds to the earth. Rather dangerous been proved by experience; but to raise water from business transporting lightning. I think it would wells, the pump has hitherto been considered the be considered contraband by the "U.S," or " Mermost convenient apparatus. But if the invention chant's Union,' or any common carriers; but it is of Mr. Hanreau, of Meaux, France, succeed accord-particularly fitted for this work. Did you ever see ing to his anticipations, pumps will no longer be a leaf entire as to its edges? It is always pointed, necessary. Take a case in which it is proposed to and these points, whether they be large or small, raise a certain height the water of a spring or stream are just fitted to handle this dangerous agent. rising in an ordinary well. This well is extended These tiny fingers seize upon and carry it away to the necessary depth for affording a fall below the with ease and wonderful despatch. There must level of the spring or stream sufficient for actuating be no delay; it is "time freight." True, some. a hydraulic ram placed a short distance from the times it gathers up more than the trunk can carry, bottom of the well. At the bottom of the well a and in the attempt to crowd and pack the baggage boring is effected until the absorbent bed is reached. the trunk gets terribly shattered, and we say that The characteristic feature of this arrangement con- lightning struck the tree. But it had been struck sists in intercepting the water of the spring or a thousand times before. stream by means of an annular trough communi- worked. cating with a reservoir, from which the water descends into the hydraulic ram through a conduit. One portion of the water escapes through the valve of the ram and flows away through the tubing into the bed which absorbs it. The other portion is raised by the action of the ram through the pipe into a reservoir, where it is employed for any The opening of the tubing is covered by a grating for preventing the entrance of foreign matter, which might eventually choke the tubing, and also destroy the absorbent properties of the bed. If the yield of water in the well is too small, a second reservoir may be connected to the first by means of a siphon with intermittent action.

desired purpose.

THE LEAF AS A WORKER.

DE R. J. S. SEWALL, in the American Entomolo gist and Botanist, says, Let us consider the 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 looms, draws so many cars so many miles an hourwe 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 same 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

This time it was over

CARMINE.

HIS beautiful red pigment is obtained from the

Tschinen 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 appear-
ance of small berries or seeds, being of a grayish
purple colour, and in this state they form the
cochineal of commerce, and are exported to this
It
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
of manufacturing. It was first prepared by a
Franciscan monk at Pisa, who discovered it acci-
dentally while compounding medicines containing
cochineal, and in 1656 it began to be manufactured.
A great many experiments have been made to ex-
tract it in a state of absolute purity, but repeated
trials have proved this to be a most delicate opera-
tion, and one requiring great skill, as well as very
careful attention.

or three

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 less rapidity. And what a huge electrical machine! minutes; 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 earth the 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 constructed rød. What, then, must be the agency poured cautiously through fine white linen into of a single ferest in disarming the forces of the another well cleansed vessel. This liquid is again storm of their terror. Nature furnishes the light-made to boil, and when it commences boiling the ning, and it furnishes the lightning rods. Take a cochineal is added; next autour, and at last the hint, then, and plant trees.

THE HALFPENNY POSTAGE.

TH HE bill for further regulation of duties of

pestage, and for other purposes relating to
the Post-office, has just been published. For the
purposes of the Act, the Channel Islands and the
Isle of Man are to be deemed parts of the United
Kingdom. The Act will come in force on Oct. 1st.
Allowance will be made for stamps to those who at
that time may be in possession of them. Any pub-
lication coming within the following description
shall, for the purposes of the Act, be deemed a
newspaper-that is to say, any publication cousist-
ing wholly or in great part of political or other
news, or of articles relating thereto, or to other
current topics, with or without advertisements,
subject to these conditions:-That it shall be pub
shed in the United Kingdom; that it shall be
published in numbers at intervals of not more than
seven days; that it be printed on a sheet or sheets
unstitched; that it have the title and date of
publication printed at the top of every page. The
proprietor or printer of any newspaper may register
it at the General Post-office in London, at such
time in each year, and in such form, and with such
particulars as the Postmaster-General from time to
time directs, paying on each registration such fee,
not exceeding five shillings, as the Postmaster.
General, with the approval of the Treasury, from

time to time directs. On and after the 1st of
October, 170, registered newspapers, book packets,
pattern or sample packets, and post cards, may be

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 cautionsly discharged, and the sediment is exposed to the sun to dry. When dried it is gathered from the plate with a fine brush or a feather, and this very fine and very beautifully coloured powder is the carmine of cochineal.

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 Mines held on Saturday, July 2nd, the following awards were inade:-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. 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 Molal and prize of books were not competed for this year..

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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.

MECHANICAL MOVEMENTS.

to lever, A, which is provided with two pawls, B and C, hinged to its upper side, near shaft of wheel, D. Small crank, E, on upper side of lever, A, is attached by cord to each of pawls, so that when pawl C is let into contact with interior of rim of wheel D it moves in one direction, and pawl B is out of gear. Motion of wheel D may be reversed by lifting pawl C which was in gear, and letting opposite one into gear by crank E.

216. A device for assisting the crank of a treadle motion over the dead-centres. The helical spring, A, has a tendency to move the crank, B, in direction at right-angles to dead-centres.

217. Continuous circular motion into a rectilinear reciprocating. The shaft, A, working in a fixed bearing, D, is bent on one end, and fitted to turn in a socket at the upper end of a rod, B, the lower end of which works in a socket in the slide, C. Dotted lines show the position of the rod, B, and slide, when the shaft has made half a revolution from the position shown in bold lines.

218. Buchanan and Righter's patent slide-valve motion. Valve A is attached to lower end of rod B, and free to slide horizontally on valve-seat. Upper end of rod B, is attached to a pin which slides in vertical slots; and a roller, C, attached to the said rod, slides in two suspended and vertically adjustable arcs, This arrangement is intended to prevent the valve from being pressed with too great force against its seat by the.pressure of steam, and to relieve it of friction.

211. Self-recording level for surveyors. Consists of a carriage, the shape of which is governed by an isosceles triangle having horizontal base. The cir-D. cumference 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.

218. 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

219. Continuous circular motion converted into a rocking motion. Used in self-rocking cradles. Wheel, A, revolves, and is connected to a wheel, B, of greater radius, which receives an oscillating motion; and wheel B is provided with two flexible bands, C, D, which connect each to a standard or post attached to the rocker, E, of the cradle.

220. Arrangement of hammer for striking bells. Spring below the hammer raises it out of contact with the bell after striking, and so prevents it from interfering with the vibration of the metal in the bell.

221. Trunk engine used for marine purposes. The piston has attached to it a trunk at the lower end of which the pitman is connected directly with the piston. The trunk works through a stuffing-box in cylinder-head. The effective area of the upper side of the piston is greatly reduced by the trunk. To equalise the power on both sides of piston, high-pressure steam has been first used on the upper side and afterwards exhausted into and used expansively in the part of cylinder below.

222. Oscillating piston engine. The profile of the cylinder A, is of the form of a sector. The piston, B, is attached to a rock-shaft, C, and steam is admitted to the cylinder to operate on one and the other side of piston alternately, by means of a slide-valve, D, substantially like that of an ordinary 215. P. Dickson's patent device for converting reciprocating engine. The rock-shaft is connected an oscillating motion into intermittent circular, in with a crank to produce rotary motion. either direction. Oscillating motion communicated | 223. Root's patent double-quadrant engine.

shaft.

This is on the same principle as 222; but two single-acting pistons, B, B, are used, and both connected with one crank, D. The steam is admitted to act on the outer sides of the two pistons alternately by means of one induction valve, a

and is exhausted through the space between the pistons. The piston and crank connections are such that the steam acts on each piston during about two-thirds of the revolution of the crank, and hence there are no dead points.

(To be continued.)

THE MANUFACTURE OF SUGAR FROM

WT

BEETS.

WITHIN the last fifty years the manufacture of sugar from beet-roots has made rapid strides, not only in France and Germany, but also in Russia, Belgium, Austria, and some other European countries. The harvest of 1865-6 in France yielded no fewer than 275,000 tons of raw sugar, in addition to which there were about 10,000,000 gallons of strong spirits, extracted partly from roots and partly from molasses. The value of this sugar and spirit amounted in round numbers to £7,500,000; but besides this there were the byproducts of 20,000 tons of potash, value £500,000, and 1,600,000 tons of pulp, after extraction of the juice, which was valued at £1,000,000, and was eagerly bought by farmers for fattening cattle; so that the produce of that year's harvest was represented in round numbers by £9,000,000. The process of manufacture usually adopted in France was complete to the minutest particular, and so advantageously is each product turned to account that there is literally nothing wasted. As the waggons conveying the roots arrive at the manufactory they are carefully weighed, and an account kept of the quantity of the raw material received. From the waggons the roots pass to the washer, which co sists of a long, cylindrical drum, constructed of parallel rods of iron, and slightly inclined as it revolves in a tank of water. At its lower end is a inclined plane, on which the beets fall, and are passed to the first pulper, where they are cut into small pieces by revolving knife-blades. These fragments are then passed into the second pulper, where, by means of saws, the pulp is finely comminuted and put into bags made of sheep's wool, a small quantity only being placed in each bag. These sacks are piled one over another, separated by trays made of sheet-iron, and submitted to the action of a press, which extracts a great portion of the juice; after which they are taken to the hydraulic press, where the remainder is squeezed out. The juice is then run through pipes into an iron reservoir, connected by means of a valve with the monte-jus, a cylindrical vessel made

We are indebted for the facts of this article to Mr. Crookes's recent work "On the Manufacture of Beetroot Sugar in England and Ireland." Longmans & Co.

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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 carries 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 G F 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

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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; Ti 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 heating 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 a lump-breaking "machine and passed through a screen it is ready for market.

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in 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.

ON ZYMOTICS.*

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From the little town of Calstock a very large quantity vances, supports this view. The zymotic theory dressed" copper and tin ore is annually shipped. has just been stated These opinions are introduced of The first mine visited was a copper mine at a only to show how little is really known about the was going on briskly. nature or composition of the contagious material. little distance from the town just mentioned, and bere Of its existence, there can be no doubt, but of its the process of dressing the ore form, whether animal or vegetable, whether a fer- The dressing is effected by means of washing, crushing, ment, or simply some organic chemical combina- and "jigging," which operations were fully described. tion, nothing is known. With regard to the mode A large tin-mine was then visited. in which this contagious material is conveyed to in- being usually associated with quartz, tungstate of iron, dividuals, it is a common idea that it is carried or wolfram, and other minerals harder and of greater through the air, or even that it is produced de noco specific gravity than those with which copper ore is where there are bad smells, defective drainage, and generally found, a more elaborate process for dressing in low, damp sitnations. The notion that the air the ore of tin is requisite than is necessary for that of the contagious matter is singularly devoid

The oxide of tin

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 distances below each other.

ON referring to the Registrar General's reports for the last ten years, we find that in England 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; Devonian rock, while tin ore is found only when 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-complaints usually spread. When, for example, an granite is reached. This is strikingly exemplified at which is the essence of the complaint, without which infectious disease passes from one place to another. Kit's Hill, a bold elevation forming the highest land in the complaint would not exist. It is to the de- it moves along the line of traffic, not in the direc- east Cornwall. The upper part only of this hill is struction of this substance that our efforts in the tion of the wind, but along the course taken by tra- granite, the flanks and base being lower Devonian. suppression of these diseases are directed; for could vellers. When a contagious disease leaves a con- Accordingly we find copper-mines around the lower all the contagious material in the universe be tinent for an island, it always makes its first ap- portion of the hill, while the engine-house of a tin-mine destroyed, these diseases would cease to have a pearance in a sea-port. In fact, the contagious crowns the summit. place in the nosology. A knowledge of their material seems capable of being carried but a very natural history is necessary to a comprehension of short distance, probably only a few feet, by the the means to be employed in preventing their occur- movement of the air; one of the best means of disrence, and a slight sketch will therefore be given of infection is to send a free current of air through their course when attacking the individual, and of the room or space, fresh air seeming to have the the circumstances under which they spread. power of destroying or weakening, perhaps by dilution, the contagious material. Nor is there any these specific diseases anew. There is no doubt that defective drainage, and crowding of people together, predispose to the reception of these specific complaints, and are themselves the direct causes of many and serious illnesses; but bad sanitary arrangements in a house or a town never generate these epidemic disorders-they must be brought from without, and then, under these bad sanitary conditions, they spread with frightful rapidity, and cause immense mortality. An instance in proof of this may be found in the hygienic condition of England before the time when the cholera first visited us. Then the sanitary condition was probably as bad as could be, yet the cholera did not exist until it was brought over from the continent of Europe, when it spread rapidly and decimated the country. (To be continued.)

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

In the second paper Mr. Lobley gave the results of an investigation into the range and distribution of the strata, and exhibited a series of diagrammatic tables genera and families of Fossil Brachiopoda in British embodying the results arrived at, and intended to show 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-li 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 diseases called zymotic-a name which is
bad, because based upon a false theory, but which evidence to prove that bad smells, &c., produce out the lode concluded the paper.
has become sanctioned from long use-are, in
systematic medicine, known as the acute specific
diseases; acute, because always of short duration,
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 un-
known 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 suf-
fered 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.

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 out 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

Hipparitida.

MR. F. C. HILLS, of Deptford, makes the am-
Professor J. Rupert Jones said the tables would have
moniacal liquor of the gasworks of sufficient
purity to become a cheap and effective purifying agent been more complete had they embraced the results of
for depriving gas of its sulphuretted hydrogen and car- foreign as well as British research, the area of these
bonic acid. The gas liquor, when purified, is run islands being too small for satisfactory conclusions re-
through the common scrubber, and the gas allowed specting the life of any one geological epoch to be
Mr. Bath, F.G.S., thought the indication in the tables
to pass up through the scrubber. It then comes into drawn from a study of British fossils merely.
contact with purified ammoniacal liquor, which de-
prives it of its impurities, and thus the desired result of the continuance of certain genera to the present time
is obtained and all the expense of excessive labour from evidence obtained from the existence of living
is avoided. The mode of purifying the gas liquor is species in any of the seas of the globe, while the fossil
as follows:-A series of stills or vessels are placed species indicated were from the British Islands only.
was, unless fully explained on the tables, calenlated to
one above another, partly filled with gas liquor to
be purified, which runs through these vessels by confuse the student. The tables and paper were, how-
means of connecting pipes from the top to the bot-ever, of such value that he moved that they should be
printed by the association. This was seconded by Mr.
tom, where it is made to boil. By this boiling the J. Hopkinson, F.G.S., and carried unanimously.
carbonic acid and sulphuretted hydrogen and also
a little ammonia are driven off, and pass into the
liquor in the next vessel above, by which the am-
monia vapour is mostly absorbed, but not the car-
bonic acid or sulphuretted hydrogen. By passing
these products in like manner through the whole
series of vessels, the ammoniacal vapour driven off
from the boiling gas liquor is absorbed by the gas
liquor in the higher vessels, and the carbonic acid
and sulphuretted hydrogen are left free to pass
away whenever desired. If wished, the whole of
the gas may be purified entirely by this gas liquor;
but as the quantity required would be considerable,
it is perhaps best to purify the gas about two-thirds
by this process, and then to finish the purification

with oxide of iron.

SCIENTIFIC SOCIETIES.

GEOLOGISTS' ASSOCIATION.

Tthe meeting of this association, held at University

Tennant, F.G.S. (in the absence of the President, Pro-
fessor Morris), in the chair, the following papers were
read by Mr. J. Logan Lobley, F.G.S.:-
"Two Days in a Mining District,"" On the Distribu-
tion of the British Fossil Brachiopoda."

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 vegetable growth-a fungus. Some observers, especially in Adam Murray, Esq., F.G.S., exhibited a collection of Germany, aver that they have been enabled to de- specimens of ores and other minerals from East tect under the microscope the little plant which is wall, as well as : plan and section of a copperthe cause of cholera; others assert, that certain mine. fungi found in mouldy straw will produce measles The first paper contained an account of a brief visit in less than forty-eight hours after inoculation. paid to the mining district of east Cornwall, in which The Sir Henry Holland has thrown out the idea that both copper and tin mines are very numerons. these diseases are produced by clouds of animalcules author dwelt with evident pleasure on the beautiful passing over a country; and he considers that the scenery of the river Tamar, which meanders through the way in which an epidemic or contagious fever ad- richly wooded valleys on the eastern side of this district, to which the river is of very great service, as it facilitates the conveyance of the ores to the localities where they are smelted.

* Written by J. Wickham Legg, M.D., and extracted from The Student.

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 obser vations 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 roads are hilly any advantage results from the use of work for horses to draw a load up hill on a tramway than on a macadamised road?"

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, complained bitterly of the prevalence of worms, which infest corn and other crops, the highest cultivated Corn-fields being the most infested. Fowls are known to be the most indefatigable worm destroyers, pursuing their prey with extraordinary instinet and tenacity. But Therefore M. fowls cannot conveniently be kept upon every field, nor are they wanted there at all seasons. Giot has invented a perambulating fowl-house, which is described as follows: "He has large omnibuses, fitted up with perches above, the nest beneath. The fowls are spot, and, the doors being opened every morning, the shut in at night, and the vehicle is drawn to the required fowls are let out to feed during the day in the fields. Knowing their habitation, they enter it at nightfall without hesitation, roost and lay their eggs there.

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