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ilnll redness,—not only without carbonization or combustion, but absolutely with very little change, and scarcely any pressure whatever. This oil has double the specific heat of water, and possesses high conducting power, so that it not only receives heat readily from the fire, but imparts it readily and equitably to the evaporating vessels or other substances with which it is brought into contact. The heat can thus be maintained with the greatest regularity, and at a temperature sufficient to melt lead, distil mercury, generate steam at high pressure, or evaporate the most delicate liquid. Messrs. Doulton have succeeded in producing earthenware evaporating pans and retorts which are impervious to the oil; and in future the distillation of the strong acids may be conducted in perfect safety, without costly platinum retorts, or the direct and dangerous application of heat to glass; whilst the distillation of turpentine, alcohol, and other inflammable fluids may be conducted by the circulation of this liquid heated from a furnace in another building. As the fluid oil is so much more readily heated than water, there is a great economy in fuel, particularly as the surface to which the heat is applied may be almost iudefinately extended within the smallest space. We may expect to see the system applied to steamships, to locomotives for the Underground Rail- way, and indeed to a thousand purposes where freedom from smoke and economy of space are matters of importance ; and we would especially direct the attention of architects to its application to the purposes of warming and ventilating public buildings, and particularly hospitals. By circulating this liquid at a temperature of 600° Fohr., it is possible to deliver in a given room six times the amount of heat which the same bulk of water, heated to 200° Fnhr., would convey, and this would be done by the consumption of little more than half the fuel. The patentee proposes to use it for cooking, baking, soap-making, oil-refining, and for metallurgical operations, where regular and often high temperatures are required. In fact there seems to be scarcely any manufacture on purpose for which heat is used to which this invention cannot be applied, especially where economy both of fuel and space ore considerations to be studied. In the engraving, A represents the furnace, containing a coil of iron piping through which the heating medium circulates; B is a tank or reservoir containing a Bnpply of the heating medium; Cis a pyrometer; D is a still, still-head, and dip-arm as applied to Coffey's patent method; E is a shallow pan for evaporation; and K is a stoneware pan for distillation, &c, through which the heating medium returns through the coil to tank B.
STEAM BOAD-BOLLING IN ENGLAND.*
THE steam-rood roller has now been more or less in use in Paris forthe last ten years. In carrying out their six years' contract with the Paris municipality, the engines of the contracting company there have already rolled down nearly half a million of cubic yards of road metalling. That the interests of the users of the roads,
• From the E winter.
whether human or equine, are fully served, is evident to the most casual observer amongst the visitors to that beautiful city. Knowing many European capitals, we feel free to say that the Paris roods are unequalled, whether for their regular and smooth surfaces, their precise contours, or their freedom from mud in winter and dust in summer. It has been officially estimated that the diminution in draught due to the steam rolled surface saves an enormous animal snm to Parisian owners of horses and vehicles. This is easily accounted for when we remember that the draught on loose metalling is five times more than where the stones have been "run in" by the traffic; and that draught progressively rises to this five-fold amount on patches in varying states of consolidation. Apart from equine and vehicular wear and tear caused by increased draught, it continually happens that horses are injured on the loose sharp stones by spraining the joints of their legs; especially on stones of too large a size to be consolidated by the comparatively narrow and light felloes of ordinary vehicles. During this very seaBon we know that more than one wealthy carriage owner proposed to bring actions for damage done in this way to horses passing on the macadamized part of Piccadilly, Still, much as West-end people object to loose metalling, they prefer its occasional appearance to the dangerous slipperiness of stone setts. No rider with any care for his own neck or his horse's knees will, if he can help it, ride over pavement. There are qualities in which a'macadamized road must always excel paving. It is cheaper to lay down, it gives a better foothold, and it is free from the fearful noise of paved setts.
At first sight it might be expected that such roads as in Paris must be dearly paid for in maintenance. In England, at any rate, consolidating roads by rolling is looked upon as merely a luxury for parks and pleasure grounds; as it is believed that common vehicles roll roads down at no cost to road maintainers. In all probability, road-rolling was thus regarded when first used in France and Prussia; or, at the most, it was hoped to prevent injuries to horses, vehicles and harness. But the virtue here displayed was found to be its own reward in the form of much saving in maintenance. It was in our own pages that attention was in England first markedly drawn by Mr. Paget to the waste of metalling on unrolled roads, and generally to the great economical advantages of the process. From seven estimates formed at different times, under the most varying circumstances, by different engineers —amongst whom are Field-Marshal Sir John Burgoyne, the engineer of the Seine Department, and Mr. Holmes, the Sheffield borough engineer —an average of 40 per cent, saving in metalling can be proved to be produced by the imperfect process of horse-road rolling as against traffic rolling. Now the experience of the last ten years in Paris, as compared with the experience of the previous thirty years or thereabouts, since horserolling was adopted, has shown the French engineers that the Hteam-rollcd roads last twice as long as horse-rolled roads; or, in other words, while the horse-roller diminishes road maintenance by 40 per cent., the remaining 60 per cent, of any total to be expended, when no rolling is used, is itself brought down by one-half where the steam roller is applied.
With such results, and placed, as they have been lately, in a clear light before the public, it would be wonderful if the use of the steam roller —especially as a cheaper and more efficient form than that of the Paris company is obtainable—did not spread even with such conservative local authorities as own. Liverpool, Sheffield, Leeds. Manchester, Birmingham, and Maidstone now actually possess and use steam 'rollers, while the Americans, always eager to take hold of mechanical improvements, are very rapidly extending their employment throughout the States.
After this bare statement of facts there comes the obvious inquiry why the steam roller is not regularly used in London? And this our question has, in fact, been very often asked of late. Intercourse between London and Paris, especially amongst the equestrian, and, therefore, roadjudging, classes is too frequent to allow such a capital improvement, in use for years, to escape notice. On the prodigious area of the 1,200 miles of macadamized roads in the metropolitan district alone there must be a wide field for the steam roller. It has been estimated that there ore some 22,000,000 of square yards of macadamized roadway, solely within the thirty-eight metropolitan parishes and districts. Taking the districts of Plumstead and Lewisham, which are the ffarthest from the centre of London, as giving an approximate, in low, measure—in the ratio of the area of their roads to their total acreage—of the proportion of roads to area on the outskirts, it can be calculated that, within twelve miles of Charing-croBs, there are more than 40,000,000 of square yards of macadamized roads. Then, many miles of new roads are being every year laid down on the outskirts of this metropolis—the largest in the world—which, according to the estimate of the engineer of the City Commissioners of Sewers, doubles its population every forty years. In fact, there can be little doubt that at least fifty steam road rollers could be profitably employed in London and its neighbourhood.
We move now to ask why London should be so behind Paris, Bordeaux, Hanover, the main cities of the United States, and our own large provincial towns? The answer is to be found in the subdivision of metropolitan administration into districts mostly too small to purchase a steam roller. Even a larger vestry would have to pause before such an expenditure of capital, with its heavy depreciation for wear and tear; it would have to consider the facts that the single roller could not well be used at all seasons, while on the other hand, at some times, more than one could be profitably employed ; that a special staff for working, applying, and repairing the roller would have to be kept up, with an attendant increase of responsible duties for the, in many instances, already over-worked surveyors.
Within the last few months a good amount of steam road rolling has been done in London, in at least six different districts, while several others are proposing to try it. Allured by the prospects of saving their heavy annual bills for granite metalling, these worthy vestrymen, each set forming a board perfectly ignorant of, and entirely ignoring, each other's doings, expect that the very first passages will save in metalling. In this they go to the other extreme of confidence in steam rolling, as its full economical effects are only felt after at least a couple of years. Nevertheless, vestries naturally hesitate, for the reasons we have just given, actually to buy steam rollers.
In fact, there simply remains the Ubuoi British remedy for British maladministration, decentralization, and administrative supineneBS—a jointstock company for steam rolling by contract the roads of London and of other places where a steam roller en permanence could not be afforded. In this, even with a centralized administration, the French have been before us, finding it best to have the work done by a company, which, indeed, is yielding good profits to its shareholders. With these views, we are pleased to be able to state that a steam road-rolling company is being formed with every prospect of success. We understand that the committee of the Royal Society for the Prevention of Cruelty to Animals, under the presidency of the Earl of Harrowby. after making vain attempts, extending over years, to introduce steam road-rolling, have, subsequent to an investigation resulting in an expression of warm approval of the objects of this company, rendered substantial aid in setting it on a sound basis.
M.I/on Vaillant has published some interesting observations on the marine animals of the Breton coast.
Curiosities of Mathematics. By James Smith. Londoii: Simpkin, Marshall, and Co.
MR. JAMES SMITH, the Liverpool cyclometer and deniolisher of Euclid, has buen at it again. Poor Euclid has not been left a toe to Htand on. His opponent, pursuing his triumphant career of discovery, now finds that sundry of the propositions of Euclid's Elements '' are inconsistent with certain other propositions," and ."are not true under all circumstances,"—especially 8 and 13 of Book VI. "are inconsistent with each other;" und though he freely admits "that the three angles of a plane triangle aro together equal to two right angles," one is exhibited whose smallest angle is about 2", aud each of the others, whether any reader "can or cannot see it," are right angles. As for De Morgan and modern professors iu general, it is absolutely a fact that, "Mathematicians have never discovered that if the length of a straight line be represented" (according to I. 47) "by V 15, its true length is á + 7-24ths of 3 = 3-875, and not 3-872, See., the extracted root of 15" (the dolts !). If any of his present live correspondents " can't see, " these things, Mr. Smith "can't help it, but the fact remain* (aud in italics) notwithstanding." Moreover, they each and all, in pretending to solve a case under Book I., to which our redoubtable author challenged them—running straight into his trap—"made the ratio between the length of two unequal lines the same as the ratio between the areas of squares on two other unequal lines iu the diagram," than which '• nothing can bo more absurd." Thus he lias caught " live blind mice," and dropped them "into a quagmire of geometrical inconsistency, contradiction and confusion."
Alas 1 however, for those who love to watch the effects of the northern Smith's doughty arm, the net has this time been spread in vain in the sight of his old victim, Professor Be Morgan, who is like в chicken of education, too sly to accept the cook's repeated invitations to "come and he killed ; " and hence it must be confessed that the above are the chief plums to be picked from our cyclometer's new cake or v. The Liverpool "■ Catholic Will Case " being very prominent when he was challenging two reverend professors to discuss his "interesting and novel problem " (the ratio of the two segmeuts made by the perpendicular on the longest side of a triangle whose sides are¡5,4, aud 3), one of his lay victims, understanding these clergymen, prone of them, had voluntarily entered the lists, and originated the title " Cariositie* of Mathematics," thought proper to suggest the following Will Case, as a curiosity involving, like Mr. Smith's, a little ciphering, and more worthy their solution.
A testator left a property to be thns employed, after being turned into money:—His executors were to advertí чо а гецие it to tuo Archbishop ot the proTince to iinswor these throo quostions. The last chapter of Scripture that contain» this phrase, "If any man have an ear, let him hear," ends, ho said, with a riddle coureruing a name, whose letters, taken as numerals in the Arithmetic of that day (which knew of no numerals but the Greek letters), were to nótate a given number. Now, as it is plainly implied by tho writer tit that and succeeding chapters, that to all mou of some future time a knowledge of this name was to be extremr.hj important, the Archbishop was to be solicited to state publicly, for the general good, these ovidontly а.чггггатаЫе things: (1) whether the New Testament contains any паше,—that ii. noun in the nomiuative case—that answered the said ndille ; (J) whothor it contained more than oue; and (8) «lint tho паше, il any, was; or the names, if more than one, were. On his Grace doing so, the advertising was to cease, the remaining money to be laid up six mouths, and then put at his disposal, for his trouble, unless cither ol his answers wore meanwhile proved false—iu that ease paid to the persons proving it so. But until his Grace might answer all three, the advertising was to go on till a named sum was expended; after which the same questions were to be put to the ltomau Catholic Archbishop alone, with the same conditions; and unless, or until he might answer, their advertising was to continue as long as any money remained. On execution of this will commencing, the Protestant Archbishop set n_ clerk to work examining in Bruder's " Cuncoutantiœ Noví Tettam ".-г í; " every noun occurring in the nominative; beginning from A, working 8 hoars per day; and the average tiuic to find and examine each, was 3 minutes. Meauwhilu the daily cost of asking his Grace as publically as tiie will required was i'i. Presently ho answers question 1; but before he could answer 2 or 8, though another day would have enabled him, tho sum named was expended; so that the inquiry haJ to be transferred to tho Komish prelate. He, guessing that the Protestant lind probably used tho above concordance, and begun alphabetically, thought fit to set two clerks to work and begin contrariwise from the end, or lather from the last possible noun (as no word containing л or » could answer the riddle, these biters having their numeral meanings too high). As these clerks cheeked eaeli other (and moreover, were paid by job, instead of tho truly British method, by time) theirprogress was at ju ,t thrice the rate of tho Protestants: aud presently, without cuing all through the book, they enabled their master
both to confirm the answer given to question 1, audio answer -2 ami 3; so that after six months lie obtained tho disposal of the remaining legacy. Prnhlrm.—How much •'f tiie advertising expense would have been saved had the Protestants obtained it by gettlngthrougu theirwork и day sooner?
Of course this needs no more algebra than our friend " Gimel " would tolerate, but the answering would involve the whole of the work that the testator's bribe is supposed to extract from the two prelates themselves.
HOW TO OBTAIN STEREOSCOPIC PHOTOGRAPHS OF MICROSCOPIC SUBJECTS. AT the conclusion of an occasional half-hour's examination of stereoscopic pictures we have frequently felt tempted to decide that for the future we should take only binocular views of nature. An ordinär)' photograph, however well taken and however much it may command admiration, is but a picture after all; but when a pair of pictures have been obtained from standpoints differing only a few inches, aud are made to coalesce- by means of the Btereoecope, the representation before the spectator ceases to be a picture; it then becomes a reality— "Seems ! nay is."
We have sometimes, says the British Journal of Photography, for the sake of amusement and effect, taken a binocular picture of a piece of apparently interminable forest brushwood, which as a single picture was [simply an unmeaning mass—a sort of pictorial chaos—aud have listened with interest to the comments made on the single picture aud its hopeless intricacies compared with the laudatory exclamations which greeted its appearance iu the stereoscope. If auy photographer has attempted to take a view of a well-frequented flsbing station when the harbour was tilled with boats, he will have obtained the host idea of iutricacy and coufusion that we cau suggest. Some single aud stereoscopic pictures of Wick Harbour that we took ou one occasion are probably the best specimens of pictorial order versus confusion that we have ever seen.
Laying aside the ordinary camera as an agent for obtaining views from nature, we now take up the microscope. What we desire, first of all, to direct attention to is the increased fascination that centres in some subjects wlieu examined by the binocular microscope as compared with tho ordiuary single tube. The solidity and beauty of these tiny objects when thus viewed are simply marvellous. As is the photographic view of natural scenery when seen in the stereoscope and out of it, so is the affect conveyed by a minute body when viewed in a biuocular and iu a monocular microscope. In one the image is a fiat picture; in the other it is a solid body. The production of large and perfect representations of the most minute bodies by means of photography is now, thanks to such men as Drs. It. L. Maddox and Woodward, a fact realized by every man of science; but tho work iu this direction is not complete so long as monocular representations only are made.
A short time ago we were desirous of obtaining an ordinary stereoscopic picture of a small object— the head of a crane-fly. We had previously taken a negative of it about three inches in size, so as to form an object for the magic lantern, but we afterwards considered it desirable to make a sterensemiic slide from the вате subject. Without dwelling upon the various methods we intended adopting, aud our reasons for so doing, we shall now explain the method that we finally adopted, and which yielded results of the most gratifying character. As a prelude to what we are about to say, we may state that any reader who possesses the "most ordinary achromatic microscope and a quarter-plate camera may obtain quite as good and successful results as лес did.
The object-glass that we employed on the occasion was the lowest power in our possession, viz., one of 2in. in focus. This permitted the whole of the object to be distinctly displayed in the field of the instrument. Having placed the microscope iu a horizontal position, aud so as to obtain a ray of sunlight on the mirror beneath the stage, we then placed in position the slide to be photographed— with this difference, however, from the ordinary modo of proceeding, that we inserted under one end a small wedge tHpering up to the tliickness of a penny piece. At the eyepiece cud of the tube we placed the camera, from which we had previously removed the lens, and having excluded all light except that which was transmitted through the tube, we adjusted the size of the picture by sliding in or out tho ground glass, and the focus by means of the rack. In this position we took the first of the binocular negatives. Now removing the wedge from under the end of tho slide, we transferred it to tho opposite end aud proceeded as before. We thus obtained two pictures—similar, yet different. When printed from ami mounted on a stereoscopic slide the effect was exceedingly beautiful : it was as if a hujje model had been prepared in a trauslncent material. To heighten the effect we made a transparency on glass, and.
by means of chlorising and washing with Schlippes salt, we converted the image into a fine transparent brown exactly the colour of the original.
There is only one class of subjects that can be effectively represented in the maimer we have described. We do not suppose it would be possible to obtain in this way representations of the higher kind of microscopic "game" at which Dr. Maddox flies, and for this reason :—When operating with very high powers on difficult test subjects, not only is the thickness of the covering glass an element of disturbance in the definition (one, however, now easily got over), hut its inclination at other tlian a right angle to the axis of the objective may create insurmountable confusion. This, coupled with the fact that high powers arc absolutely devoid of depth of focus, and therefore that an object so placed that oue part is nearer to the lens than another could not all be sharp, seems to us to preveut this method from being serviceable when such objects as Po'lum scales and Xaricnlœ are to be photographed with powers only one-twelfth of an inch.
About two months since a new invention in connection with the microscope was made public, bv which the very highest class of test objects may be photographed, as they are now seen, with foil Btcreoscopic effect. The excellent binocular micro scope introduced by Mr. Wenham, aud now well known to microscopists, answers only when low powers are used, beiiiR, in consequence of its internal construction (which we need not here de scribe), quite unsuited for showing any object under an object-glass of short focus. But atthe lust meet ing of the Royal Microscopical Society, Mr. J. W. Stephenson, F.R.M.S., ire,exhibited a new form of binocular microscope invented by him, which, if w~ mistake not, will soon eclipse every other fonu hitherto in nse, from the original binocular bv Wee ham to those which, while professedly improvements upou it, still depend upon the same principle.
IMPROVEMENTS IN OPTICAL APTABAÏTJS.
A SPECTROSCOPE of a very valuable description has been invented and constructed by Mr. John Browning, F.R.A.S., ami has been exhibited at some of the soirées of the Boyal Socitbr. An ordinary spectroscope, with a train oí prisuvs,"и a difficult instrumcut to nse, because to see each part of the spectrum in perfection the prisms should be adjusted to give the minimum angle of deviation of the particular rays under examination. Thus fresh adjustments of the whole of the optical parts of the spectroscope are necessary to see to perfection each of the different hues' of the spectrum. With Mr. Browning's new instrument, whatever part of the spectrum may be in the centre of the field of view the prisms and telescopes are always in the ЬеяЧ position for viewing that part of the spectrum. To effect this the prisms and telescopes are mounted upon a hinged framework of bars of brass iu such я way that when any line of the spectrum is brought into the centre of the field of view the prisms always stand so that the rays from that part of the spectrum shall be bent by the prisms as little as possible from their original direc tion before euteriug the intrument. When this is done the prisms are in the position known to opticians as " the angle of minimum deviation" for that particular line of the spectrum. A spectroscope which thus arranges the prisms automatically is necessarily rather an expensive instrument; the ordinary spectroscope, on the other hand, is verytroublesome to adjust. The best instrument for orilinary observers who do not intend to plunge very deeply iuto the science of spectrum analysis is the "direct-vision spectroscope," in which compound prisms of peculiar construction are enclosed in a straight brass tube, and all the trouble of adjustfrighten young stadents of mathematics from attacking nient is rendered unnecessary.
Mr. J. L. Lane, of 28, Charles-street, Hattor garden, has' invented a new photographic canten and appurtenances, to facilitate the working ofthr wet process in the open air by tourists or photo graphers. His object is to do away with the darV tent or dark box ordinarily used under such circiou stances. By Mr. Lane's plan the plate is find, coated with collodion iu the open air, then it Ls placed ou a peculiar "dipper," a framework mad* of varnished wood and silver. The handle of this dipper passes through the top of the dark slide, and the plate, after being placed on the dipper, is at once drawn up into the dark slide. The bottom of the dark slide is then fixed upon the top of а vertical wooden case, containing the nitrate of silver glass bath, and all the points of junction агг so nicely fitted that no light can reach the plate of the bath. The plate is sensitized by being pnsutxl down, dipper and all, into the nitrate of silver bath. and when it is sensitized it is drawn up again Luto the dark slide by the handle of the dipper. Then » pause is made that the plate may drain itself, aft er wliich a little sliding door closes the bottom of the dark slide, so that it can be removed from the bath, and no diffused light can reach the plate. Aftrr oxposure a peculiar little jerk is given to the dark slide to dislodge the plate from the dipper, and the fact tliat this jerk has to l>e given seems to an observer to bo an objectionable feature. Tin; dislodged plate then rusts upon the wooden bottom of the dark slide, which is fixed over the developing bath just as it had previously been fixed over the sensitizing bath. Avikh the bottom of the slide is •withdrawn the plate fulls into the developing solution, and the process of development may be •watched through pieces of orange glass fixed in the wooden casing of the trough. Afterwords the picture may be taken ont, washed, and fixed in daylight. \Ve have seen a letter from one gentleman wko has had a set of this apparatus on trial, and he speaks very well of it, but it requires prolonged experience- to prove its real value. Supposing there ar." no practical objections, it will be very useful as tending to abolish—in landscape photography— such inconvenient and heavy accessories as dark tents and dark boxes.
Some improvements in electrical lanterns have just been made by Mr. Ladd, the optical instrument maker, of Regent-street. The new lamp resembles a vertical cylinder in shape, and it has two "fronts" nearly at right angles to each other, with flanges to carry lenses. When tlirowing a spectrum upon a screen, electrical lanterns are never placed so us to lace the screen, but at an angle, and the prisms in front of the slit bend round the rays of lij^lit. Hence, by having a cylindrical lamj) with two flanged fronts, the electric microscope may throw direct images npon the screen from the one front, while the prisms may at the same time or afterwards throw a spectrum upon the same screen from the other front without moving the lantern. Moreover, an image of the luminous arc may be thrown by tho one front, then its lenses may be covered, and a spectrum of the light from the same arc be immediately exhibited by permitting the rays to pass through the spectroscopic apparatus. This lamp, then, will do the work usually done by two lamps at public lectures, and much time in adjustment of apparatus is at the same time saved by the speaker and his assistants. In the side of this cylindrical lantern is fixed a little tube, with a lens at one end and a piece of blackened ground c,lass at the other. A small image of the luminous carbon point is thus projected upon the ground glass, so that the lecturer may see that the luuunous arc is in exactly the right place, this being a point of considerable importance in using tho electric microscope. When this instrument is used a very slight shifting of the elevation of the are throws the image otf the screen. A fine horizontal line ruled across the ground glass serves as a guide to the true position of the luminous arc. Iiiside the lamp is a common gas jet, so that when it is necessary in spectrnm experiments to frequently elinnge the carbon points, there is some light inside the lantern to see to work by. Altogether the new lamp is a very useful instrument to the public lecturer.
One eveuiug, towards the close of the session of the Royal Institution, Mr. Browning exhibited in the library of the institution a spectroscope with one or two prisms of tho ordinary construction, but between these prisms and the eye of the observer was a direct-vision compound prism, with outer edges of a circular shape to lit in a tube, the two ends of the prism, however, being of course inclined planes. This prism and its tube could be turned r..uud and round by tho baud of the observer. It is plain, therefore, that in one position this directvision prism aids the others and produces more .lispersion ; by turning it round it acts against the others, and produces less dispersion; by taking it away altogether, an intermediate effect is obtained. It follows, therefore, that three different degrees of dispersion ore placed at the command of the observer by a simple motion of the hand.
ON PYROMETERS." By C. William Siemens, F.R.S., D.C.L. rPHE mercury thermometer, which enables us to X estimate ordinary temperatures with such admirable precision, fails to indicate heats exceeding the boiling point of mercury (500* Fahr.), and although many attempts have been made to prodnco a reliable high temperature thermometer (or pyrometer) it can hardly be said that such an instrument is now in the hands of the practical metallurgist.
Amongst the attempts which have been made in this direction the Wedgwood pyrometer occupies the hrst position. It is based upon the peculiar property of fire-clay to shrink permanently when exposed to intense heat, and upon the supposition that the amount of shrinkage in question was proportionate to the intensity of the heat to which the ball of fire-clay had been exposed. The error involved in this supposition becomes at once apparent if we consider that the shrinkage of the ball is caused by the expulsion of waterof hydration which must necessarily take place cliiedy at one particular temperature. It is proved, moreover, by the very discordant and, in fact, impossible results, recorded
* Paper reaa before the Iron and Steel Institute nt lie me«tloa in South Wales, September 6,1670.
in chemical works as being obtained by means of this instrument. Thus we find it stated in Dr. Larduer's popular treatise, that cast-iron melts at a temperature of 17,977 Fahr., and that iron welds at a temperature of 21,000" Fahr., whereas it con be proved that the utmost temperature to be obtained by the combustion of carbon with a blast of atmospheric air cannot exceed 4,fi00° Fahr., which degree of temperature far exceeds the points of heat to be met with in metallurgical processes, not excepting even the melting point of mild steel, which comes nearest to the maximum point here indicated.
Amongst tho other pyrometers that have been proposed from time to time is the air pyrometer, which is limited by the melting or softening point of the vessel confining the air, the pyrometer by difference of expansion of two metals which has lately been brought forward in a compendious form by Mr. Gauntlet, but which cannot be relied upon beyond a point approaching red heat, at which permanent elongation of the metal set in, and a pyrometer by contact of two dissimilar metals setting up an electric current capable of measurement, which, however, is by no means proportionately progressive with increase ef temperature.
Another pyrometer has been based upon the wellfounded supposition that the specific heat of metallic bodies is the same at various temperatures, and that by measuring the heat of a ball of metal after it has been exposed to the heat to be estimated, a true measure of its intensity is obtained. I have myself constructed an instrument upon this wellknown principle, which has found considerable favour with ironmasters in measuring the temperature of hot blast, and for other purposes. It consists of a portable vessel composed of three concentric cylindrical vessels of thin copperplate, the two intestine spaces being filled, the inner one with cow-hair, and the outer one with atmospheric air, and the two together forming an excellent barrier against loss of heat from the interior of the vessel. A delicate mercury thermometer is fixed in the interior of the vessel, being protected by a perforated shield, and furnished with a movable sliding scale showuig pyrometer degrees, of which one is equal to 50 ordinary degrees. The instrument is accompanied by balls of copper or platinum, which are so adjusted that fifty of them wonld bo equal in thermal capacity to an imperial pint of water. Each ball is perforated by a hole through which a rod is passed in exposing the same to the action of the heat to be measured. Immediately before wring the instrument, an imperial pint of water is poured into it, and the pyrometer slide is so moved that its zero point coincides with the top of the mercury column in the thermometer tube. The ball is thereupon exposed to the heat for two or three minutes, and plunged into the water. The mercury will be observed to rise, and the absolute temperature of the place measured is ascertained by adding the reading on the pyrometer scale, opposite the new level of the mercury, to the degrees of temperature indicated by the thermometer before the ball was introduced. In using ordinary dexterity very satisfactory readings may be obtained with this instrument, but its application is limited to the point of heat nt which the metal ball employed begins to deteriorate, nor can it be employed for measuring tho temperature of inaccessible places.
It has been luy endeavour for several years to devise a pyrometer of a more universal applicability, and containing in itself more absolute proof of correctness, and, after a long series of experimental investigations I have succeeded in producing an instrument which I can confidently recommend to tho practical metallurgist. It is based upon the peculiar properties of the pure inetals to offer an increasing resistance to the passage of an electrical current with resistance of temperature. A platinum wire of known electrical resistance is wound upon a cylinder of fire-clay, npon which a helical path has previously been cut to prevent contact between the turns of the wire. The coil of wires, so prepared, is enclosed within a cylindrical casing of platinum if the temperatures to be measured exceed the welding heat, or of iron or copper if lower tomperature only requn'es to be measured. The two ends of the coil of wire are brought ont endways, and are attached within the protecting tube to thicker leading wires of copper, insulated for a short distance by being passed through pipe-clay tubes, and further on by india-rubber, or gutta-percha, terminating at the measuring instrument, which may be placed at any convenient distance. This latter is of peculiar construction, its characteristic feature being that the usual calculations necessary in determining electrical resistances by the Wheatstoue or other methods are dispensed with, and a reading in degrees of n large scale is at once obtained by so placing the index lever that the electrical current, generated in a small battery and passed through the measurine instrument, including the platiiiMm wire of the pyrometer, produces a deflection of the galvanometer needle. These degrees do not themselves express the temperature, but the temperature they represent is expresseil by a table of reference, which accompanies each instrument. The pvroineter coil itself, v/ith its protecting casing, jay either be fixed permanently at points, the temperature of which ought to be ascertained
from time to time, or it may be introduced into a furnace through a door or aperture for only a minute or two, which time suffices to obtain a reading of the instrument. The latter is the only practicable method where the temperature to be measured approaches a welding heat which would in time destroy the protecting case of platinum or any other material; whereas, the former method of fixed coils will be the most convenient for measuring the lower temperature of drying or annealing stoves, or of the hot blast supplied to blast furnaces. At iron works with a number of hot blast stoves, a protected coil may be fixed within the hot blast tube leading from each Btove towards the blast furnace, and the leading wires from each of these coils bo brought into the office where the measuring apparatus wonld be placed. By such an arrangement the temperature of the blast of each stove of the furnace could be measured and noted at frcqnent intervals by a clerk without leaving the office, ami very perfect, record and control be thus obtained. The correctness of this instrument depends solely on the ratio of increase of electrical resistance in the platinum wire, with increase of temperature. This rise is considerable, the resistance being increased fourfold by an increase of temperature from the freezing point to about 8,000° Fahr. The ratio of increase is, however, not uniform, but follows a parabolic law which I have ascertained by a series of careful observations embodied in the table, and which form the subject of a separate communication to the Royal Society. I wish it to be understood that, in developing these principles, I have been animated solely by a desire to fill up a blank in the means at our ilisposal to carry on metallurgical inquiries with such a degree of certainty as could not hitherto be realized, without seeking for any commercial reward through the Patent Office or otherwise.
[The paper was illustrated, and the pyrometers mentioned exhibited.]
IMPROVEMENTS IN POWER LOOMS.
\ MONO recent improvements in power looms -i\. that of Messrs. Davics and Yates, of Manchester, which we this week illustrate, must take a prominent place. This invention, which is patented, consists in an improved "positive letting-off" and "swell motion," which, besides other advantages, are applicable to any existing loom or fabric woven. In ordinary looms the letting-off is effected by means of weights ami levers, which require almost constant attention and have to be altered as the diameter of the beam becomes less; the constant vibration of the weights being destructive to the loom, and causing many of the warp threads to break. The principal advantages of this improvement in the letting-off motion consist in it being entirely self-rcgulatiug, so that when the warp is once set it requires no attention till the whole length is finished. It also acts as a vibrator in regulating the tension of the warps during the shedding and beating homo of the weft shot, and by this means lengthens the duration of the healds and reeds. By this process a more perfect and uniform cloth is produced, while greatly economizing both power and labour. The inventors calculate that, in average work, 150 per cent, will be saved in healds and reeds, while the breakage of the warp threads will be reduced fully 200 per cent. The objects effected by the new swell motion are a reduction of the driving power, a lengthening of the duration of the shuttle, and the production of an even pick with great accuracy. Several manufacturers have tested the improvements and expressed their entire satisfaction with them, and looms fitted with them can lie seen in operation daily at the premises of the inventor, 35, Back Oeorge-street, Manchester. On referring to the illustrations the letting-off motion is seen in Figs. 1, 2, and 3; Fig. 1 representing a back elevation of the loom, having adapted thereto tho improved arrangement of letting-off apparatus. Fig. 2 represents a transverse sectional elevation of the loom, having the improvements applied, showing the position of the apparatus when the " sley" is on ; its front centre beating home the weft shot. Fig. 3 represents a detached view similar to the last, showing the position of the apparatus of the warp beam at the time the shed is closed.
In these figures, a is a rod forming the fulcrum of the levers M 61, supported by the bracket secured to the framing *■ of the loom immediately above tho flanges of the warp beam it. The upper or shorter levers h h curry or support a rod c passing umh r and supporting the warp threads, as they pass from the beam <1 of the lower or longer levers hi hi, carrying a rod/that lies against the yarn of the beam and passes under the last fold or lap of tho warp ends. The upper levers carrying the rod e are supplied with projecting brackets g g which support adjusting screws anil nuts h h. The lower end of the screw underneath the bracket g is connected to a rope or chain £, which passes first around the drag pulley of tho warp lieani, then under a carrb r pulley I connected to tho lower frame of the loom below the warp beam ; after which it passes onward
continued until the required tension of the »агр b, obtained. When the tension is obtained and this loom in action, the beating up of the sley when closing in the weft shot (at which time the crank is on its front centre as BJiown at Fig. 2) draws forward the top rod e, thereby causing the, lower rod/ to exert a pressure upon the warp threads, which gives an excess of tension to the same at the time of heat ¡rig home the weft shot and effects a cover upon the cloth under manufacture. On the return of the sley (Fig. 3) the upper rod or bar с inclines outwards by reason of the action of the spring i through the medium of the ropes or chains k к, thereby causing the lower rod/ against the beam to become relieved, so as to reduce its tension upon the warps ; simultaneously with which the ropes or chains encirelia^ tiie drag pulleys of the beam are also eased, which allows the necessary quantity of yarn to be drawn easily from the warp beam sufficient for the next pick, and the healds to open the shed without strain or tension upon the yam. Again, as the diameter of the beam becomes reduced with the delivery of yarn thereform, the lower tension rod/is carried with the passing warp threads gradually nearer to the beam, thereby effecting during the delivery of the yarn a proportionate reduction of tension to the spring forming the coupling between the ends of the ropes or chains /.• k. When it is desired to let back the warps, a temporary release is given to the beam through the medium of the lever n, which, when pulled over into a position the reverse of that shown at Fig. 1, relieves the spring i; the original tension being readily obtained on recommencing weaving by placing the bar in its original position.
Figs. 5, 6, and 7, relate to the new swell motion, and consist in forming the same of an inclined construction which increases its distance in the box from the part where the shuttle first enters, and also for supporting and maintaining the swell in the orifice or opening in the back of the shuttle-1юх independently. Fig. 5 represents a plan view of the shuttle-box showing the position of the swell in relation thereto. Fig. 6 represents another modification of the swell and its supporting br;. having an adjustment for giving more or less inclination to the swell in the box, and Fig. 7 represents a transverse section of the same.
In these figures d is the swell supported by th« brackets or arms « secured to the stop Tod J; the distance the swell d is allowed to protrude in the shuttle-box g is regulated by the set screws h h. Tims when the shuttle enters the box the swell moves bodily back, giving by the form of its inclined surface an increased resistance to the shuttle on its completing its race ; but when the shuttle is again expelled the resisting incline acting then upon the shuttle in its reverse direction at once relieves and assists by the pressure of its incline the expulsion of the shuttle into the opposite box.
THE IRON AND STEEL INSTITUTE.
Г1111Е second provincial meeting of the Iron and l Steel Institute was this year held at Merthyr Tydvil, under the presidency of the Duke of Devonshire. There was a large attendance of members, including Lord Frederick Cavendish, Marquis of Bute, Sir John AUevue, Bart., K. Fothergill. M.P., W. S. Boden, M.P., E. M. Iïichards, M.P., Joseph Dodds, M.P., B. Samuelson, M.P., and nearly two hundred gentlemen connected with the iron and steel trades of the kingdom.
The noble President opened the business proceedings by alluding to the pleasure with which the members must turn from the contemplation of the scenes that have recently taken place on the continent to the matters to be considered by the meeting. A report was submitted by the council in which they stated that arrangements had been made for publishing, in connection with the iastitute, a journal, in which, besides the'usual proceedings of the institute, all matters connected with the manufacture of iron and steel at home and abroad, will be fully reported. The council recommended that Mr. Henry Bessemer should be nominated president elect for the year 1871. This proposal was very warmly received by the meeting, and a resolution approving of the suggestion of the council was moved by the Duke of DevonshireMr. Bessemer acknowledged the compliment, and said his best endeavours should be given to furthering the objects of the institution, ami he hoped to fulfil his duties, if not with entire satisfaction to himself, at least without injury to the institution.
The names of fifty gentlemen were then announced as having been duly elected members.
The first paper was read by Mr. Wm. Adams, Cardiff. The author estimates the extent of the South Wales coalfield at 937 square miles, or 600,000 acres, and the quantity of workable coal at Sti.UOO millions of tons. Towards the eastern end of the field the coal is chiefly bituminous, in the central part it becomes more free burning, whilst Mt the western portion of theI field it is anthracitic. The argillaceous iron ores are abundant and good.
They form an aggregate thickness of 60iii. to 70in.,
but are not so extensively worked as they were
a few years ago, chiefly in consequence of the
introduction of cheaper ores from Northampton
and elsewhere. Besides the argillaceous iron ores,
there are deposits of hematite in various localities
bordering upon the field. The annual production
of coal is about 13) million tons, and of ironstone
♦H million tons. The intersection of the coalfield
by deep valleys places the lowest seam within
1,000 yards of the surface, so that the whole of the
minerals can be won by pits of less than that depth
for over two-thirds of the field, that is, between the
eastern outcrop and the Vale of Neath. The dip
along the north outcrop ranges from 3in. to 6in., and
in some cases to Bin. per yard, while on the south
it varies from 9in. to 12in., La. and 18in.
per yard. This gradual flattening northwards
leaves a large area in the centre of the field
comparatively flat. The most numerous faults
run from N.W. to S.E., and vary in amount
of vertical displacement from 250 to 300 yards.
Others running in au east and west direction have
a displacement of from 400 to 500 yards. The
greatest fault is one in Pembrokeshire, estimated
as giving a displacement of 2,000ft. The deepest
pits now sunk range from 304 to 435 yards.
The second paper was on improved pumping and winding machinery at the Castle Pit, Merthyr Tydvil, belonging to Mr. R. T. Crawshay. Mr. G. J. Snelus read a paper on " The Condition of Carbon and Silicon in Iron and Steel." With respect to carbon the author detailed the nature of the experiments by which he demonstrated that carbon is only mechanically combined in cast-iron. The author expressed his belief that there is no definite chemical compound of iron and carbon, but that the absorption of carbon by iron is a case of chemical solution, and he supported this statement by reference to the phenomenon of solution in general. The effect of silicon upon iron and steel is to render it hard and brittle, and in all probability the reason why Fairbairn and others have found pig-iron to increase in strength by several successive meltings is that by these fusions more or less of the silicon is removed. While melting, however, the iron gradually takes up sulphur and phosphorus from the fuel, and in the end the deterioration due to these substances more than counterbalances the increased strength caused by reduction of the silicon. Steel which contains more than one-tenth per cent, of silicon is brittle, and though it is a rare thing for Bessemer steel to be faulty from this cause, it may sometimes occur, thus proving, along with the analysis of Bessemer metal taken during the blow, that iu the Bessemer process the silicon is not removed before the carbon as in the puddling and refinery processes, but along with it. A rather long discussion followed the reading of this paper, and afterwards a discussion took place upon a paper read at the last meeting of the Institute on "A New Method of Designing Bails."
The members afterwards visited the extensive works of which Mr. R. Fothergill, M.P. for Merthyr, is the principal proprietor, and the Cyfarthfa Iron Works, belonging to Mr. Crawshay.
Mr. C. W. Siemens read, on reassembling, a paper on pyrometers, a report of which we give elsewhere.
A paper was read by Mr. Jeremiah Head, on certain questions which affect the durability of boilers. The author alluded to the usual mode of supporting cylindrical boilers, and detailed his plan by which they are suspended and the usually destructive effects of repeated coolings and contractions are obviated. The system has been in operation at Middlesbrough for some time, and is reported to be working successfully.
Mr. Ferdinand Kohn read a paper on "Alloys of Iron and Manganese," showing that for the important compound of iron and manganese, called spiegeleisen, which is extensively used in the manufacture of Bessemer steel, can be substituted a compound of iron and manganese about to be manufactured in Scotland.
The remaining days of the meeting were spent in visiting the various iron works, &C., of the Principality.
EXETER NATURALISTS' CLUB. The Exeter naturalists recently visited the Cheddar Pass, in the county of Somerset, where Mr. W. W. Stoddart, F.C.S., F.G.S., delivered an address on '• The Geology of Cheddar." After a brief summary of the geological history of the British Isles, he called attention to the peculiar character of the cliffs, observing that it was entirely owing to their being carboniferous limestone. At the commencement of the Liassic period ;tbat part of England was uplifted and disturbed by volcanic agency. The underlying Devonian strata were elevated to 1,079ft. above the mean sea-level, the highest part being near Beacon Batch. While this elevation was proceeding, the limestone beds were broken in every direction, giving rise to innumerable cracks and fissures. When these were situated deeply in the rocks, they were simply closed cavities, penetrated only by water. In many parts of the uni.
dip8 these fissures communicate with each other, forming what are called "swallet holes." When, however, these cavities were nearer the surface, they often became open to the atmosphere, serving as ilins for animals and retreats for mankind. One remarkable feature in the Cheddar Pass is that on one side the rood the cliffs ore absolutely perpendicular, while the other is sloping, and covered by a considerable quantity of debris. Mr. Stoddart explained that this arose from atmospheric and water action, combined with the different positions of the limestone beds, one side of the Pass being more amenable to the force of wave-action than the other. A map was exhibited, showing the outline of land and water as it existed after the close of the Glacial period, and that the country south of Bristol must formerly have been an assembly of islands, between which must have been strong currents of water. Afterwards the land became elevated, and converted into swamps and morasses, around which lived the bear, rhinoceros, deer, and many animals now extinct in England. In a gravel-bed, 50ft. below the surface, a large number of teeth and bones have from time to time been collected. In another gravel-bed, above this, and separated by sand, mud, and peat, have been found pottery and other proofs of man's presence. The evidence seems to prove the correctness of other observations in other places, that traces of man were more recent than traces of many of the extinct animals. Barometrical observations showed that the highest point of the Cheddar Cliffs was about 955ft. above the present mean sea-level. The volcanic product which burst through the crust of the earth, and formed the Clifton and Cheddar Gorges, may be observed in many parts of the country. In conclusion, Mr. Stoddart alluded to the old Roman lead-mines on the Mendips, which once were considerable. Even now, large quantities of lead, zinc, and iron ores are found in the Meudip range. On the conclusion of the address the company returned to the font of the Cliffs for the purpose of exploring the more recently discovered of the two large caverns. This cavern is easy of access, with the exception of ascending a few steps and stooping slightly at two parts. At the head of it is a fine open space, lofty and imposing; but there is nothing very wonderful about the marvellous oddities it is advertised to possess. Mr. Pengelly, F.R.S., F.G.S., gave a short geological dissertation on the cave, and humorously remarked that some writers could review a book best before they had read it, and as he had never been in that cave before, he could probably lecture about it best without examining it, for if he began to investigate be should probably meet with difficulties he could not explain. He considered that it was clearly not a fissure, but the rock had been hollowed out by the action of water. Mr. Vivian was of opinion that at one time the cave had been filled with water—a view which was borne out by the fact that when first discovered there was a pool of water in the place which has been drained off. The cavern was illuminated with magnesium wiro.
MAIDSTONE AND MID-KENT NATURAL HISTORY SOCIETY.
At a recent meeting of this society, the Rev. Walter Mitchell, vice-president of the Philosophical Society of Great Britain, gave an address upon "The Geometrical Structure of the Hive Bees' Cell." He said he had adopted the above title as there were 250 different species of bees in this country, not one of which possessed the geometrical accomplishment, and very peculiar construction adopted by the hive bee. This we called the domesticated bee, because it always followed in the steps of civilization, or rather preceded them, for in North America the red Indian knew immediately the hive bee was established in the forest that it would be shortly followed by civilized man. The bee's cell was the most marvellous thing in creation, as far as our wisdom was concerned, in interpreting the works of the Creator, for those marvellous cells were made of a substance which it was extremely difficult for the bee to procure, and out of this substance it manufactured its houses, its streets, and its city. This city had three different classes of inhabitants—the Queen bee, a few hundred males or (hones, and several thousand neuters or working bees. He then pointed out that a bee on a given excursion fixed on a particular flower when it was collecting pollen dust, such as a wild rose or a lily, and visited those flowers only. The other bees collected honey for mixing with the pollen, and for the winter supply, which is put in the cells and sealed up. There was no creature whose habits the ancients were so fond of investigating as that of the bee. Virgil had written a great deal about bees, but none of them could tell from whence the bees obtained their wax. Some supposed that it was pollen, but on modern chemists burning it, they found that while pollen gave off an ash, wax gave none. This problem was, however, solved by John Hunter, tho celebrated naturalist, who, on dissecting a bee, found that in the abdomen there were certain small bags containing a white substance, which, Oil burning it in a candle, proved to be
wax, and it was, therefore, an animal secretion. The bee, therefore, had a chemical manufactory. He then described how the bees, during the summer months, gorged themselves with honey that this secretion might be produced. Iu the construction of its cells from this substance the bee showed marvellous geometrical skill. Not only had the bee, led by its divine instinct, to gather honey and store it for the winter, when it knew it could get no food out of doors, but it exercised great economy in the use of that precious substance out of which it constructed its cells. The cells consisted of a great number of hexagons, or six-sided figures. The wasp, which had been a paper maker since the creation of the world, made his paper out of wood, but he placed his comb, not vertically but horizontally. He made hexagonal cells, but he only mode his houses on one side of the street—not back to back, as the bee did, and be simply covered in the bottom of his cell with a flat piece of paper. He displayed in this a certain amount of economy, but not the greatest amount of economy. The bees' cell on the contrary was terminated with lozenge-shaped bodies—like the diamond panes of a window—which, when they put their cells together, formed the bottom of a house, on the other side of the street. The lecturer then described how the great French naturalist, Reaumur, by the aid of an eminent mathematician, discovered that the measurement of these cells by the differential calculus was exactly 109° 28', and that they gave the greatest possible internal space with the greatest economy of material. The lecturer said, therefore, he con clnded that we had not yet discovered the marvellous mechanism by which the bee produced this wonderful arrangement; and, with regard to the theory of natural selection, suggested by Mr. Darwin, he pointed out that the bee could not derive its instinct from its parents for the working bees were neutera. The bees were wonderful architects. Among the wild ones there was the mason bee and the carpenter bee. Some were very fastidious, and would only line their cells with rose or poppy leaves. He then referred to the marvellous power of the bee in obtaining propolis to strengthen the structure of its cells, and in decreasing the size of the entrance of the hive in those seasons when the death's head moth was abundant, so that it could not get in, and by imitating the voice of the Queen bee be enabled, with impunity, to steal the honey. In conclusion, he said the more we studied the works of the Divine Geometer and the Divine Architect the more we should advance in philosophy and science. It would keep man's pride of intellect in check, and we should learn to study with child-like simplicity the works of Divine wisdom.
ENGLISH MECHANICS' SCIENTIFIC AND
MECHANICAL SOCIETY. The fifth monthly meeting took place on the 7th inst., in the society's room, Mechanics' Institute, Manchester.
The chair was taken by Mr. J. McEwen, the president, at 8 p.m., and the transactions of the evening announced were as follows:—1. A paper on Gas Meters, by Mr. James Bentley. 2. Discussion on the subjects which stood over from last meeting —viz., Action and Description of the Ejector Condensor; Clayton's Patent Scraper; The Practicability of the Birmingham Patent Safe and Sure Sectional Wrought-iron boiler ; how it is for Steam power, for comparative consumption of coal, &c.
Mr. Bentley, in introducing his essay to the society, said his reason in choosing the subject was owing to the general absence of knowledge with re gard to the internal construction of gas-meters, although every house, office, and workshop in mechanical communities was supplied with the same.'
After describing the use and work performed by gas meters, the history of the invention was traced from its origin, and the 'following instruments mentioned. 1. Sir William Congreve's, as one of the first instruments proposed for the indication of the quantity of gas passing from the main cock at the consumer's house. 2. Mr. Samuel Clcgg, to whom the honour was conferred of having invented and constructed the first real gas meter. 3. Mr. John Malam's invention; and that although this was claimed to be the copy of the preceding one, a special committee who investigated the charge gave their verdict in favour of Mr. Malani, by awarding him their gold medal for his invention of a gas meter, new, ingenious, superior to oil others, and likely to be of great benefit to the public. The construction of wet, dry, and compensating meters was then explained and illustrated by a collection of open meters, and oth ;rs having glass fronts—the merits and defects of mush being pointed out, with the various Acts of Parliament passed with regard to the same.
The thanks of the members was awarded to Mr. Bentley for his interesting essay. A discussion on the subject followed, in which the description of a recently invented hydrocaiburctted gas lamp was given.