THE

THURSDAY, FEBRUARY 22, 1872

ROCK

THERMOMETERS AT THE ROYAL OBSERVATORY, EDINBURGH

THE HE whole of the observations made with these instruments (reading to hundredths of a degree Fahrenheit) from 1837 to 1869 having been reduced on a uniform plan, and found to exhibit some well-marked supra-annual cycles, a paper on the subject and on their relations to the sun-spot cycles of similar period but diverse shape was sent in to the Royal Society, London, on March 2, 1870.

Since then two eminent astronomers, one of them being Mr. Stone, the newly appointed Astronomer Royal at the Cape of Good Hope, and the other Mr. Cleveland Abbe, Director of the Cincinnati Observatory, have published somewhat similar deductions touching atmospheric temperatures in reference to sun-spots; Mr. Stone basing on thirty years of South African temperature observed by his indefatigable predecessor Sir T. Maclear; and Mr. Abbe on sixty years' temperature observed on the elevated station of Hohenpeissenberg near Munich, under the superintendence of Dr. Lamont, the Bavarian Astronomer Royal; both parties, equally with myself, using the same famous series of observations of sun-spots, as made by M. Schwabe, and discussed both by Prof. Wolf and Prof. Balfour Stewart. More recently still a Canadian writer, employing the returns of the Toronto Observatory for many years past, considers that he has established a connection between the amount of annual rainfall there and the sun-spots; and of these again with the periods and dates of several interlacing streams of circum-solar meteors. And within the last few days the Radcliffe Astronomer announces in his report for 1871 that the mean azimuthal direction of the wind at Oxford, rigorously computed from automatic records during the last eight years, varies year by year through a range of 58° on the whole, between maximum and minimum of visible sunspots; the tendency of the wind to a westward direction increasing with the number of spots, and with such west wind, it is to be presumed, the amount of rain also.

These results touch closely on the hopes of physicists to render meteorology more of an exact science by getting at its cosmical relations, but they also touch equally close on another point where the highest science is at present completely dumb, although too it is the very point where the utmost amount of benefit might be conferred on the largest numbers of the people, viz., some approximate indications of the character of the seasons for a year or two beforehand; or indeed, very much as I did make a first attempt, for the two winters of 1870-71 and 1871-72, in the paper presented to the Royal Society in the spring of 1870.

How intimately the well-being of the poor generally, as well as of the agricultural classes, depends on those characteristics of weather which no scientific society can at present .oretell, and no Ministry prevent in their destructive effects to the national revenue when they do come, the following letter may serve as a better example than anything that I could prepare on theory alone :

VOL. V.

:

"Webb's Green, Hales Owen, June 12, 1871

"To C. Piazzi Smyth, Esq., Edinburgh

(Copy)

"Sir, I am a reader of Chambers' Journal and a farmer of some 600 acres. In the publication of Messrs. Chambers I read that you had expressed an opinion from certain observations you had made that the late winter would be very severe. For the general run of weather prophets I have very little respect; but every respect for opinions that are the result of scientific induction.

Consequently I conducted my farming operations with due regard to your prognostication, and as the result has been a profit to me, I write to thank you. Gratitude has been defined as 'a lively sense of favours to come,' and from that view and in consideration of the present weather if you could give me your opinion of the weather that you think likely to prevail for some time to come I should feel much obliged.

"I have not troubled you with this epistle entirely from a selfish point of view, for besides being a farmer I am unfortunately an employer of a very underpaid class of workmen, hand rail makers.

"Now that stocks of wheat are exhausted, meat is a luxury to which railers cannot aspire; and if the season continues ungenial, before the harvest of 1872 there may be absolute scarcity of bread. I want to get up a fund for emigration, but if you could give me any information as to the probabilities of season that would dispel my gloomy anticipations for next winter, I should rejoice.-I am, &c., &c. (Signed) "THOMAS BISSELL"

But I have so little desire to incur responsibility for any weather predictions that I have gladly availed myself of the opportunity of the publication of the 13th volume of the Edinburgh Astronomical Observations to lay before the public by means of the several Plates 11 to 15 inclusive a complete graphical representation of the whole series of Edinburgh rock-thermometer observations, and on which I will merely venture the following explanatory remarks:

1. The most striking and positive feature of the whole series of observations is the great heat-wave which occurs every eleven years and a fraction, and nearly coincidently with the beginning of the increase of each sun-spot cycle of the same eleven-year duration. The last observed occurrences of such heat-wave, which is very short lived and of a totally different shape from the sun-spot curve, were in 18348, 18464, 1857·8, and 1868.8, whence, allowing for the greater uncertainty in the earlier observation, we may expect the next occurrence of the phenomenon in or about 1880'0.

2. The next largest feature is the extreme cold close on either side of the great heat-wave; this phenomenon is not quite so certain as the heat-wave, partly on account of the excessive depth and duration of the particular cold wave which followed the hot season of 18348. That exceedingly cold period, lasting as it did through the several successive years 1836, 37, and 38, was, however, apparently a rare consequence of an eleven year minimum occurring simultaneously with the minimum of a much longer cycle of some forty or more years, and which has not returned within itself since our observations began. Depending therefore chiefly on our later observed elevenyear periods, or from 18464 to 18578, and from the latter up to 1868.8, we may perhaps be justified in concluding that the minimum temperature of the present cold wave was reached in 1871'1, and that the next similar cold wave will occur in 1878.8.

S

February 1872

C. PIAZZI SMYTH

DARWIN'S ORIGIN OF SPECIES The Origin of Species by means of Natural Selection; or the Preservation of Favoured Races in the Struggle | for Life. By Charles Darwin, M.A., F.R.S. Sixth edition, with additions and corrections. (London: J. Murray, 1872.)

FE

EW are the writers, scientific or otherwise, who ca afford, in every successive edition of their works, to place side by side the passages which they have seen reason to alter, from a change of view or any other cause. And yet to this point we find especial attention called in each succeeding edition of Mr. Darwin's "Origin of Species." And herein lies the true humility of the man of science. Science is often charged with being arrogant.

But the true student of Nature cannot be otherwise than

humble-minded. That man is unworthy of the name of a man of science who, whatever may be his special branch of study, has not materially altered his views on some important points within the last twelve years.* The means at our command for obtaining correct views of the laws which govern Nature are ever increasing, and if we only

Let knowledge grow from more to more,

this can but cause that

More of reverence in us dwell, reverence for the eternal constancy of Nature's laws, with respect to which we even yet know so little. But a false pride more often tempts men to conceal than to avow their change of opinion. Mr. Darwin carries the contrary practice perhaps to an excess. But such a course necessarily disarms criticism of its sting; and if the learner sometimes ventures to point out wherein he differs from the master's conclusions, it is only in the hope that the interchange of opinion may lead to a removal of the difficulties which prevent a complete accord of thought.

The sixth edition of the "Origin of Species" is considerably smaller than its predecessors; but this does not arise from any diminution of matter, but from the use of smaller type. There has been, in fact, considerable addition, and our province will be simply to call attention to those points in which previous editions have been amended or amplified. Already, in the fifth edition, Mr. Darwin had stated that the able criticism of his work which appeared in the North British Review had induced him to modify his views with regard to the frequency of the occurrence of characters which are not useful to the *The first edition of the "Origin of Species" was published in 1859.

It has always seemed to us that one of the weakest parts of Mr. Darwin's statement of the theory of natural selection is the emphasis with which he asserts that single instances of departure from the law would prove the theory to be unsound. In the present edition, speaking of the rattle of the rattlesnake-the only effect of which has been stated to be to direct to the snake the attention of its enemies-he goes out of the way to repeat that "if it could be proved that any part of the structure of any one species had been formed for the exclusive good of another species, it would annihilate his theory." Why it would annihilate his theory, we must confess we are unable to understand; since Mr. Darwin repeats in this edition even more emphatically than in previous ones that "he is convinced that natural selection has been the main, but not the exclusive, means of modification of species." Since then other causes have been at work to cause the evolution of species, why may not some of these causes be able to produce parts beneficial to the race rather than to the species? In the special case, however, under consideration, the rattle of the rattlesnake, an American naturalist comes to the rescue of the Darwinian theory. Mr. Darwin was probably not aware at the time of writing that Prof. Shaler had stated his belief, from the result of observation, that the rattlesnake's rattle is actually beneficial to it, its object being to imitate the sound of the cicada or other insect which forms the food of many birds, thus attracting them within its power, and accounting for the apparent "fascination" of its prey, which must now be consigned to the limbo of travellers' tales.

The greater part of the additional matter in this edition is naturally devoted to a reply to the objections urged in Mr. Mivart's "Genesis of Species." In replying to Mr. Mivart's objection to the theory that "mimicry" has resulted by the process of natural selection, on the ground that the early stages of resemblance would have no useful tendency, the following sentences appear to us to be open to objection, or to be wanting in clearness :- "But in all the foregoing cases the insects, in their original state, no doubt presented some rude and accidental resemblance to an object commonly found in the stations frequented by them." "Assuming that an insect originally happened to resemble in some degree a dead twig or a decayed leaf.” What is meant by the "original state" of an insect? Every insect-form must have been evolved from some previously existing simpler form by a gradual process, and the "rude or accidental resemblance" must be due to the operation of the same causes that produced the finished likeness. We must acknowledge that Mr. Darwin appears to us to fail to grapple with the difficulty in the way of the application of his theory, that either the early stages of the " mimicry" are useless, or that the exact reproduction of figure and pattern in the "mimicing" insect is a mere freak of nature. Mr. Darwin states his belief that "the sight of birds is probably sharper than ours," which would tell heavily against the utility of the first approaches towards resemblance; Mr. Wallace, if we recollect rightly, has expressed a contrary opinion.

Mr. Mivart's objection with regard to the curious fact

that in the Pleuronectidæ, or Flat-fish, the eyes are opposite in the young state, and afterwards become placed both on the upper side of the head-that this change must have taken place suddenly, since any small approach to it would not be useful-is met by an ingenious argument, previously advanced by Malm. It is stated that "the Pleuronectidæ, whilst still very young and still symmetrical, with their eyes standing on opposite sides of the head, cannot long retain a vertical position, owing to the excessive depth of their bodies, the small size of their lateral fins, and to their being destitute of a swimbladder. Hence, soon growing tired, they fall to the bottom on one side. While thus at rest, they often twist, as Malm observed, the lower eye upwards to see above

them, and they do this so vigorously that the eye is pressed hard against the upper part of the orbit. The forehead between the eyes consequently becomes, as could be plainly seen, temporarily contracted in breadth. On one occasion Malm saw a young fish raise and depress the lower eye through an angular distance of about 70°." The objections urged by Nägeli in his "Begriff und Entstehung der naturhistorischen Art," with respect to plants, that the families of plants differ chiefly from each other in morphological characters, which appear to be quite unimportant to the welfare of the speeies, are combated on the ground that we ought to be exceedingly cautious in pretending to decide what structures now are or have formerly been of use to each species. While admitting that in earlier editions he underrated the frequency and importance of modifications due to spontaneous variability, Mr. Darwin points out that many peculiarities of structure, lately supposed to be simply morphological, are now known to be intimately connected with facilities for fertilisation.

On the whole it seems to us that each succeeding edition of the "Origin of Species" lessens the distance between Mr. Darwin and those who believe that the influence of natural selection, though a vera causa, has been overrated as an element in the evolution of species. If it is admitted that important modifications are due to "spontaneous variability," that natural selection is not the exclusive means of modification, Darwinians and nonDarwinians have equally before them the problem to discover what these other laws are which are co-efficient in the production of new species, and what part each of these plays in producing the final result. Until this is accomplished we can hardly consider the great problem of the Origin of Species as solved. Towards the solution of it, however, the labours of Mr. Darwin will ever be held as having contributed a larger share than those of any other naturalist. When we look at the title-page, and see that a work which has produced a greater revolution in the scientific thought of the day than any published in this country since Newton's "Principia" is yet only in its eleventh thousand, and reflect that, although this is not a small sale for a scientific work, yet books which contain the germ of no new thought, and contribute not one iota to our sum of knowledge, have sold their hundreds of thousands, we cannot but think that in the coming age, when the people will really care about science, our descendants will regard this unworthy fact in the light that we do the unpopularity of the writings of Milton and Goldsmith during their lifetime.

We must not omit to mention a very useful addition, for the unscientific reader, made to this edition, in the shape of a glossary of the principal scientific terms used, prepared by Mr. W. S. Dallas.

ALFRED W. BENNETT

MAXWELL ON HEAT

Theory of Heat. By J. Clerk Maxwell, M.A., LL.D. (London: Longmans and Co. 1872.)

IT

T is very seldom that we meet with a book so instructive and delightful as Prof. Maxwell's "Theory of inasmuch as it supplies a want which has been long and Heat." It has peculiar claims upon the student of Physics, widely felt. The point of view is undoubtedly a new one,

and to enable our readers to perceive the value of the book, we ought to make a few remarks upon the kinds of text-books that we have hitherto had. In these books the aim has been to inform the student's mind, and the fault to inform it too minutely and too exclusively. They have been of two classes-elementary books, in which the information is given in a popular manner, and advanced books, through the pages of which mathematical formulæ are very liberally interspersed.

In reading such a book the strength of the student's book be elementary, he is bent upon acquiring a good mind is devoted to one or at most two objects. If the knowledge of the facts, along with a knowledge, more or less complete, of the experimental methods by which these facts have been obtained. If, on the other hand, the book be an advanced one, his strength is devoted to grappling with studied both classes of text-books, he rises from their peBut after he has and overcoming its analytical difficulties. rusal with the belief that there is something wanting before he can have a thorough grasp of the subject, and a clear view of its truth and beauty. He has followed the experimenter only too zealously into his elaborate and accurate calculations, or it may be the mathematician into his profound investigations, and he now begins to realise the truth of the poet's saying

He who hath watched, not shared, the strife
Knows how the day hath gone,

and to sigh for some elevated spot from which he may obtain a clear view of the whole field. He hears vague rumours that the caloric battalions and their allies the corpuscular forces, have lost the day, but he wishes to see their discomfiture more completely with his own eyes.

Such a point of view is afforded by Prof. Maxwell. He has-wisely, we think-confined himself to this one object, to give the student a clear logical view of the whole subject; nor has he broken the unity of his treatment by going into details, whether experimental or mathematical. Every true student of physics should read this book, and he will unquestionably find it a most delightful study. He will, we venture to say, rise from its perusal with a much truer and wider conception of the science of heat; and if he then wants more detailed information upon any branch, he may consult one of the ordinary text-books. Another beauty of the book is the accuracy and completeness of its historical notes. The author has successfully combined the part of historian and that of logician, and has given us very many valuable references to original memoirs, in which we may see for

ourselves the first germs of the various developments. The only thing wanting in this respect is an index, into which the various facts and names of the book might have been collected with much advantage to the reader. Another point of interest in the book is the prominence given to the graphical method of representing truth. The Isothermal and Adiabatic curves are largely dwelt upon, and their usefulness in leading us to detect new properties of bodies is well pointed out. We are glad to think that the importance of such graphical representations is becoming well recognised in many departments of science. Even in pure mathematics, if we have occasion to calculate a series of numerical values from a formula, by plotting them upon curve-paper we shall discover at once by the eye if we have made a mistake in our calculation. In like manner, if we plot the result of a series of careful experiments after the manner of Regnault and others, we shall probably be able to determine from the appearance of the curve whether or not we may trust to the accuracy of our determinations.

Finally, by a series of lines similar to those exhibited by Prof. Maxwell, we come to see with great ease the relation that exists between the various properties of bodies; for instance, we see at once and as a direct consequence of the definition, that the ratio between the two specific heats is the same as that between the two elasticities.

We cannot close this review without remarking upon the good English in which this excellent book is written ; and this, we trust, will go far to convince the scientific public that the most profound and original treatment of physics is not inconsistent with purity of language.

OUR BOOK SHELF

B. STEWART

Queen Charlotte Islands: A Narrative of Discovery and Adventure in the North Pacific. By Francis Poole, C.E. Edited by John W. Lyndon. (London : Hurst and Blackett, 1872.)

MR. POOLE enjoys the distinction of being the only educated Englishman who has ever lived on Queen Charlotte Islands, where he spent two years in an endeavour to develop the mineral resources of the country. The volume therefore necessarily possesses the interest attaching to a narrative of a residence in an almost unknown country. We miss, however, those touches which add so much to the charm of books of travel, which indicate that the writer has visited many men and many cities, and is capable of contrasting the natural products or the habits of the people of one part of the world with those of another. The attraction for the author to these islands was the presence of copper, to work which a company was formed in 1862. There can be little doubt that copper-veins, and probably other minerals, do exist in the islands in quantities that would amply repay the investment of labour and capital in their working. The climate appears to be equable and agreeable, the harbours are magnificent, and the soil is rich and productive, so that we may hope that at some future time Queen Charlotte Islands will become a valuable dependency of the British Crown. If Mr. Poole's volume succeeds in drawing to their capabilities the attention of those who are competent to develop their resources, it will have performed good service.

Hints and Facts on the Origin of Man, and of his Intellectual Faculties. By Pius Melia, D.D. (London: Longmans and Co., 1872.) THE writer of this little book states in his preface that "he has brought together systems, facts, statements, and

reasons, taken from all available sources, with the view of elucidating several important truths about man, which are at the present day either called in question or absolutely denied." The extent to which he has consulted, or the accuracy with which he has quoted from, original sources, we gathered from the fact that he entirely passes over, as unworthy of notice, the systems of Goethe and Oken, and from the statement that the "Philosophie Zoologique " of G. B. Lemarck (sic) was published in 1830.

LETTERS TO THE EDITOR

[The Editor does not hold himself responsible for opinions expressed by his correspondents. No notice is taken of anonymous communications.]

A Zoological Station at Torquay

THE article on "The Formation of Zoological Stations,” by Anton Dohrn, which appeared in NATURE of the 8th inst., was read at the meeting of the Torquay Natural History Society on the 14th inst., and was the subject of an animated conversation. I am happy to add that the scheme met the warm approval of the members, and that if a station be established at Torquay, the cordial co-operation of the society may certainly be reckoned on. W. PENGELLY, Hon. Sec. Museum, Torquay, Feb. 17

The Chicago Observatory

A LETTER, signed by one of the Professors of the University of Chicago, commenting on the impoverished state of the Chicago Observatory since the great fire in that city, having had an extensive circulation through the Press, I have to request the favour of the insertion in your columns of the following statement on the subject, just received by the Secretary of the Royal Astronomical Society from the Director of the University, Prof. T. H. Safford. EDWIN DUNKIN,

Hon. Sec. to the Royal Astronomical Society Royal Observatory, Greenwich, February 22

"Dearborn Observatory, Chicago, Jan. 29, 1872 "DEAR SIR, -As the enclosed article from the London Daily News (see also London Times of January 9) might convey the impression that the Observatory is to be closed, permit me to state exactly the facts.

"The Observatory-whose funds are separate from those of the University-has, during the few years of its existence, accumulated a large stock (perhaps too large) of unpublished and 35° and 40° of declination, in conection with the German Astroonly partially discussed observations, especially upon stars between nomical Society, on Argelander's plan. A few months before the fire arrangements had been in progress by which it would gradually acquire the means to discuss and publish these obser vations, and these arrangements have been interrupted.

"So far, then, as the City of Chicago is concerned, nothing further is to be expected for the present, and, perhaps, the coming year; but as business has revived, it is expected that the difficulty of providing means will not be permanent.

"For the present it is necessary for me to give a portion of my time to geodetic and geographic-astronomical work for the United States engineers, who are conducting large operations in the central portion of the country; and the publication of our observations will be in consequence delayed.

་་

"It is but fit that I should here acknowledge the indebtedness of the Observatory to the Hon. J. Young Scammon, at whose sole expense the Dearborn Tower and the Meridian Circle Room were built, and upon whom the support of the Institution has mainly depended.

"Our thanks are especially due to those scientific friends who have so kindly given their works. Were it not for the Greenwich and other star-catalogues received by past donations, I should have found myself in no condition to accomplish the work which I am now doing for support.

"T. H. SAFFord, "Director of Dearborn Observatory "To the Secretary of the Royal Astronomical Society."

Composition of Vibrations

WHILE holding one of König's large polished tuning-forks in my hand, I happened to give it a swaying movement on the plane on which its vibrations were being performed, and immediately noticed that the space through which the fork swing was occupied by a series of bright straight lines arranged in a fan-like form. The lines spread out, or drew together, as the rate of movement impressed on the fork increased or diminished. The case was clearly one of composition of vibrations, the bright lines being merely the edges of the prongs seen in positions of instantaneous rest, where the proper motion of a prong was equal

and opposite to that communicated to it by the hand.

By taking forks of different pitch, and causing them to swing with equal velocities, the dependence of pitch on the number of vibrations performed in a given time was easily exhibited. In case this simple observation has not yet been made or described I ask its insertion in NATURE.

MR. J. BOESINGER, in the last number of NATURE, expresses his surprise at the ignorance of the photographers attached to the late expeditions, and favours them with hints, observations, and instructions still more surprising. Because he cannot see their reasons for employing equatorial stands, plates in separate frames, and long exposures, he concludes these were unnecessary; and affirms there must have been a great want of balance in their chemicals." No doubt there is a want of balance somewhere, and I diffidently submit the probability that Mr. Boesinger has lost his.

66

I would briefly state to those few of your readers who may have been misled by this correspondent, that equatorial stands driven by clock-work are absolutely necessary in the production of the best results, either by short or long exposure of photographic plates; a picture 'not perfectly sharp but valuable as a memorial," was what Mr. Boesinger aimed at (and I sincerely hope he obtained it), but the expeditions had higher aims and greater expectations. Single large plates were exposed separately, that should a corona extending many degrees be actinically present, it might find ample room to put in an appearance; in such a case had "repeating backs" been used to give many pictures on one plate, there would have been great danger from the corona of one picture over lapping that of another, to the ruin of all. Comparatively long exposures were found necessary to secure impression from the faint extremities of the rays.

HENRY DAVIS

T

moon's motion round the earth. It must therefore lie in some such direcMtion as the line MQ in the diagram, which represents, necessarily with enormous exaggeration, its deviation, OQ, from the earth's centre. Now, the actual force on the moon in the line MQ, may be regarded as consisting of a force in the line MO towards the earth's centre, sensibly equal in amount to the whole force, and a comparatively very small force in the line MT perpendicular to MO. This latter is very nearly tangential to the moon's path, and is in the direction with her motion. Such a force, if suddenly commencing to act, would, in the first place, increase the moon's velocity; but after a certain time she would have moved so much farther from the earth, in virtue of this acceleration, as to have lost, by moving against the earth's

attraction as much velocity as she had gained by the tangential accelerating force."

distance would be increased in the ratio II. 46, and her The consequences are then shown to be that the moon's periodic time increased, and the earth's period of rotation lengthened.

This reasoning perplexes me; for if the effect of a certain amount of fluid friction is to throw the line of action of the force

from MO to MQ, a fluid friction is conceivable which should throw it outside the earth altogether. Moreover, the line of attraction of the earth on the moon would be in a line not

passing through the earth's centre, a result I cannot understand, especially if the fluid friction were increased as just suggested. Nor can I see that a force in MQ, the centre of the earth being free, would tend to stop the rotation of the earth.

As I view the matter, fluid friction generates a couple tending to stop the rotation of the earth, and it is impossible to combine this couple with the force in MO, and represent the resultant by a single force. The energy lost in the form of momentum of rotation of the earth is gained in the heat devolved by the fluid friction, which is ultimately dissipated. And the final result would be that the orbit of the moon would not be appreciably altered, while the period of rotation of the earth is gradually lengthened.

Am I wrong, for the thousandth time in my life? and if so will some one try and enlighten me. Perhaps Prof. Tait will spare a few minutes to an old friend. M. A.

Circumpolar Lands

IN NATURE (Feb. 8) Mr. Murphy seems to admit the soundness of the reasoning by which I endeavoured to show (Jan. 25) that the earth's form is probably undergoing a slow progressive change, but he thinks that the statements in the first and last parts of my letter are contradictory.

If Mr. Murphy will be good enough to read again the paragraph immediately following the one which he quotes, I think he will find that there is no contradiction. "Transmission of pressure towards the poles" must tend to elevate the land in those regions. How that pressure is produced and transmitted I have endeavoured to show in the same paragraph.

However, the main proposition which I sought to establish in my paper of 1857, before alluded to, is that any spheroid of equilibrium, whether earth, sun, or any other, in motion about an axis, in cooling from a fluid state, undergoes a change of form, and with this proposition Mr. Murphy seems to agree.

Mr. Murphy has inadvertently omitted part of a sentence in making his quotation from my letter, thus representing me as speaking of a ratio with one quantity only. Queen's Coll., Liverpool, Feb. 16

GEORGE HAMILTON

The Spheroidal State of Water

I HAD the pleasure a few days ago of visiting Messrs. Johnson's celebrated iron wire manufactory in Manchester. There may be seen a series of furnaces and rolling mills which in twenty-four hours can convert a truck load of the best Swedish iron into the bright and polished galvanised wire which is now being so extensively employed to complete our very perfect system of Post Office telegraphs. Every stage of the process passes beneath the eye of the observer; the melting of the pigs, the formation of the billets, the puddling of the bloom, the shingling of the balls, the rolling of the bars, and their subsequent extension by further rolling, and drawing into telegraph wire.

The bars are cut off into 1oft. lengths, and are placed in a Siemen's regenerative furnace, where they are raised to a brilliant white heat. They are then drawn out of the mouth of the glowing furnace, and pass through a series of consecutive rollers of varying dimensions, and rotating with varying speed, ultimately flowing out in a continuous stream of iron wire. In fact, the metal is at such a high temperature and so plastic that the curves it takes in falling convey the idea of a thin, fine unbroken jet of liquid matter.

The rollers are kept cool by the constant play upon them of jets of water. The first pair of rollers is fixed close to the mouth of the furnace, which is partially closed by a moveable screw that is only raised when the attendant sprite requires to direct another bar to the attenuating process of the continuous rollers. The jet of water that cools the first pair of rollers in one furnace fell in a broken shower upon the foot-plate of the mouth of the furnace, which, from its proximity to the fire, was raised to a