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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 are 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 furthest 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-cross, 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 have 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

dull redness, not only without carbonization or whether human or equine, are fully served, is combustion, but absolutely with very little evident to the most casual observer amongst the change, and scarcely any pressure whatever. visitors to that beautiful city. Knowing many This oil has double the specific heat of water, European capitals, we feel free to say that the and possesses high conducting power, so that it Paris roads are unequalled, whether for their not only receives heat readily from the fire, but regular and smooth surfaces, their precise conimparts it readily and equably to the evaporating tours, or their freedom from mud in winter and vessels or other substances with which it is dust in summer. It has been officially estimated brought into contact. The heat can thus be main- that the diminution in draught due to the steamtained with the greatest regularity, and at a tem- rolled surface saves an enormous annual sum to perature sufficient to melt lead, distil mercury, Parisian owners of horses and vehicles. This is generate steam at high pressure, or evaporate easily accounted for when we remember that the the most delicate liquid. Messrs. Doulton have draught on loose metalling is five times more than succeeded in producing earthenware evaporating where the stones have been "run in" by the pans and retorts which are impervious to the oil; traffic; and that draught progressively rises to and in future the distillation of the strong acids this five-fold amount on patches in varying states may be conducted in perfect safety, without of consolidation. Apart from equine and vehicostly platinum retorts, or the direct and dan- cular wear and tear caused by increased draught, gerous application of heat to glass; whilst the it continually happens that horses are injured on distillation of turpentine, alcohol, and other in- the loose sharp stones by spraining the joints of flammable fluids may be conducted by the circu- their legs; especially on stones of too large a lation of this liquid heated from a furnace in size to be consolidated by the comparatively another building. As the fluid oil is so much narrow and light felloes of ordinary vehicles. more readily heated than water, there is a great During this very season we know that more than economy in fuel, particularly as the surface to one wealthy carriage owner proposed to bring which the heat is applied may be almost indefi- actions for damage done in this way to horses nately extended within the smallest space. We passing on the macadamized part of Piccadilly, may expect to see the system applied to steam- Still, much as West-end people object to loose ships, to locomotives for the Underground Rail- metalling, they prefer its occasional appearance way, and indeed to a thousand purposes where to the dangerous slipperiness of stone setts. No freedom from smoke and economy of space are rider with any care for his own neck or his horse's matters of importance; and we would especially knees will, if he can help it, ride over pavement. direct the attention of architects to its applica- There are qualities in which a macadamized road tion to the purposes of warming and ventilating must always excel paving. It is cheaper to lay public buildings, and particularly hospitals. By down, it gives a better foothold, and it is free circulating this liquid at a temperature of 600° from the fearful noise of paved setts. Fahr., it is possible to deliver in a given room At first sight it might be expected that such are proposing to try it. Allured by the prospects six times the amount of heat which the same roads as in Paris must be dearly paid for in of saving their heavy annual bills for granite bulk of water, heated to 200° Fahr., would maintenance. In England, at any rate, consoli-metalling, these worthy vestrymen, each set formconvey, and this would be done by the dating roads by rolling is looked upon as merely ing a board perfectly ignorant of, and entirely consumption of little more than half the fuel. a luxury for parks and pleasure grounds; as it is ignoring, each other's doings, expect that the very The patentee proposes to use it for cook- believed that common vehicles roll roads down at first passages will save in metalling. In this they ing, baking, soap-making, oil-refining, and for no cost to road maintainers. In all probability; go to the other extreme of confidence in steam metallurgical operations, where regular and often road-rolling was thus regarded when first used rolling, as its full economical effects are only felt high temperatures are required. In fact there in France and Prussia; or, at the most, it was after at least a couple of years. Nevertheless, seems to be scarcely any manufacture on purpose hoped to prevent injuries to horses, vehicles and vestries naturally hesitate, for the reasons we have for which heat is used to which this invention harness. But the virtue here displayed was cannot be applied, especially where economy both found to be its own reward in the form of much just given, actually to buy steam rollers. of fuel and space are considerations to be studied. saving in maintenance. It was in our own pages remedy for British maladministration, decentraIn fact, there simply remains the usual British In the engraving, A represents the furnace, con- that attention was in England first markedly lization, and administrative supineness-a jointtaining a coil of iron piping through which the drawn by Mr. Paget to the waste of metalling on stock company for steam rolling by contract the heating medium circulates; B is a tank or reser- unrolled roads, and generally to the great eco- roads of London and of other places where a steam voir containing a supply of the heating medium; nomical advantages of the process. From seven roller en permanence could not be afforded. In C is a pyrometer; D is a still, still-head, and estimates formed at different times, under the this, even with a centralized administration, the dip-arm as applied to Coffey's patent method; most varying circumstances, by different engineers French have been before us, finding it best to have E is a shallow pan for evaporation; and K is a-amongst whom are Field-Marshal Sir John the work done by a company, which, indeed, is stoneware pan for distillation, &c., through Burgoyne, the engineer of the Seine Department, yielding good profits to its shareholders. With which the heating medium returns through the and Mr. Holmes, the Sheffield borough engineer these views, we are pleased to be able to state -an average of 40 per cent. saving in metalling that a steam road-rolling company is being formed 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 steam-rolled 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.

coil to tank B.

STEAM ROAD-ROLLING IN ENGLAND.*

THE
HE steam-road roller has now been more or
less in use in Paris for the 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 uses of the roads,

* From the Engineer.

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 steam road-rolling, have, subsequent to an invesvain attempts, extending over years, to introduce tigation resulting in an expression of warm approval of the objects of this company, rendered substantial aid in setting it on a sound basis.

M. Léon Vaillant has published some interesting observations on the marine animals of the Breton coast.

REVIEWS.

Curiosities of Mathematics. By JAMES
London: Simpkin, Marshall, and Co.

stand on.

SMITH.

R. JAMES SMITH, the Liverpool cycloMR. meter and demolisher of Euclid, has been at it again. Poor Euclid has not been left a toe to 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;" and though he freely admits that the three angles of a plane triangle are together equal to two right angles," one is exhibited whose smallest angle is about 2, and each of the others, whether any reader "can or cannot see it," are right angles. As for De Morgan and modern professors in 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 15, its true length is 3+ 7-24ths of 3 = 3-875, and not 3-872, &c., the extracted root of 15" (the dolts!). If any of his present five correspondents" can't see" these things, Mr. Sinith "can't help it, but the fact remains (and 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 in the diagram," than which "nothing can be more absurd." Thus he has caught five blind mice," and dropped them into a quagmire of geometrical inconsistency, contradiction and confusion."

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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 PHOTO

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GRAPHS OF MICROSCOPIC SUBJECTS.

by means of chlorising and washing with Schlippe, salt, we converted the image into a fine transpara brown exactly the colour of the original.

There is only one class of subjects that car effectively represented in the manner we have obtain in this way representations of the scribed. We do not suppose it would be post kind of microscopic "game at which Dr. M flies, and for this reason:-When operatirvery high powers on difficult test subjects. Eg

About two months since a new invention c

is the thickness of the covering glass an de of disturbance in the definition (one, how » easily got over), but its inclination at other right angle to the axis of the objective E insurmountable confusion. This, couples: fact that high powers are absolutely devoi of focus, and therefore that an object so pls A1 T the conclusion of an occasional half-hour's one part is nearer to the lens than another examination of stereoscopic pictures we have all be sharp, seems to us to prevent this frequently felt tempted to decide that for the future from being serviceable when such objects as i we should take only binocular views of nature. ordinary photograph, however well taken and how powers only one-twelfth of an inch. An scales and Navicule are to be photographei ever much it may command admiration, is but a picture after all; but when a pair of pictures have nection with the microscope was made palo been obtained from standpoints differing only a few which the very highest class of test objects mes inches, and are made to coalesce by means of the photographed, as they are 110W seen, wit stereoscope, the representation before the spectator stereoscopic effect. The excellent binocular L ceases to be a picture; it then becomes a reality-scope introduced by Mr. Weraham, and now Seems! nay is. known to microscopists, answers only wher Photography, for the sake of amusement and effect, ternal construction (which we need not here & We have sometimes, says the British Journal of powers are used, being, in consequence of ittaken a binocular picture of a piece of apparently scribe), quite unsuited for showing ary object ani interminable forest brushwood, which as a single picture was simply an unmeaning mass-a sorting of the Royal Microscopical Society, Mr. J. W an object-glass of short focus. But at the last mee of pictorial chaos--and have listened with interest Stephenson, F.R.M.S., &c., exhibited a new form of to the comments made on the single picture and its binocular microscope invented by him, which, if we hopeless intricacies compared with the landatory mistake not, will soon eclipse every other for exclamations which greeted its appearance in the hitherto in use, from the original binocular by WED stereoscope. If any photographer has attempted ham to those which, while professedly improveto take a view of a well-frequented fishing station ments upon it, still depend upon the same prin when the harbour was filled with boats, he will ciple. have obtained the best idea of intricacy and confusion that we can suggest. Some single and stereoscopic pictures of Wick Harbour that we took on one occasion are probably the best specimens of pictorial order versus confusion that we have ever seen.

Alas! 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 De Morgan, who is Laying aside the ordinary camera as an agent for like a chicken of education, too sly to accept the obtaining views from nature, we now take up the cook's repeated invitations to come and be microscope. What we desire, first of all, to direct killed;" and hence it must be confessed that the attention to is the increased fascination that centres above are the chief plums to be picked from microscope as compared with the ordinary single in some subjects when examined by the binocular our cyclometer's new cake or π. The Liverpool tube. The solidity and beauty of these tiny objects Catholic Will Case" being very prominent when when thus viewed are simply marvellous. As is he was challenging two reverend professors to the photographic view of natural scenery when discuss his "interesting and novel problem" (the seen in the stereoscope and out of it, so is the effect ratio of the two segments made by the perpendi- conveyed by a minute body when viewed in a bincular on the longest side of a triangle whose sides ocular and in a monocular microscope. In one the are5, 4, and 3), one of his lay victims, understanding image is a flat picture; in the other it is a solid these clergymen, or one of them, had voluntarily body. The production of large and perfect repreentered the lists, and originated the title "Curio-sentations of the most minute bodies by means of sities 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 thus employed, after being turned into money:-His executors were to advertise a request to the Archbishop of the province to answer these three questions. The last chapter of Scripture that contains this phrase, "If any man have an ear, let him hear," ends, he said, with a riddle concerning a name, whose letters, taken as numerals in the

R. L. Maddox and Woodward, a fact realized by
photography is now, thanks to such men as Drs.
every man of science; but the work in this direc-
tion is not complete so long as monocular repre-
sentations 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 after-
wards considered it desirable to make a stereoscopic
slide from the same subject. Without dwelling
upon the various methods we intended adopting,
and 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 ordi-
nary achromatic microscope and a quarter-plate
camera may obtain quite as good and successful
results as we did.

IMPROVEMENTS IN OPTICAL APPARATUS.
SPECTROSCOPE of a very valuable descrip-
A
tion has been invented and constructed by
Mr. John Browning, F.R.A.S., and has been exh
bited at some of the soirees of the Royal Society
An ordinary spectroscope, with a train of prismas, is
a difficult instrument to use, because to see each
be adjusted to give the minimum angle of deviation
part of the spectrum in perfection the prisms should
of the particular rays under examination. The
fresh adjustments of the whole of the optical parts
of the spectroscope are necessary to see to perfec
tion each of the different lines 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 best position for viewing that part of the
spectrum. To effect this the prisius and telescopes
brass in such a way that when any line of the
are mounted upon a hinged framework of bars of
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
prismis as little as possible from their original direc
tion before entering 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 spectro
scope which thus arranges the prisms automatically
is necessarily rather an expensive instrument; the
ordinary spectroscope, on the other hand, is very
troublesome to adjust. The best instrument for
ordinary observers who do not intend to plunge very
deeply into 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 adjust-
frighten young students of mathematics from attack
ment is rendered unnecessary.

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arithmetic of that day (which knew of no numerals but the Greek letters), were to notate a given number. Now, as it is plainly implied by the writer of that and succeeding chapters, that to all inen of some future time a knowledge of this name was to be extremely important, the Archbishop was to be solicited to state publicly, for the general good, these evidently ascertainable things: (1) whether the New Testament contains any name,-that is, noun in the nominative case-that answered the said riddle; (2) whether it contained more than one; and (3) what the name, if any, was; or the names, if more than one, were. On his Grace doing so, the advertising was The object-glass that we employed on the occa- Mr. J. L. Lane, of 28, Charles-street, Hatte to cease, the remaining money to be laid up six months, and then put at his disposal, for his trouble, unless sion was the lowest power in our possession, viz., garden, has invented a new photographie careither of his answers were meanwhile proved false-in one of 2in. in focus. This permitted the whole of and appurtenances, to facilitate the working o that case paid to the persons proving it so. But until the object to be distinctly displayed in the field of wet process in the open air by tourists or pr his Grace might answer all three, the advertising was to the instrument. Having placed the microscope in graphers. His object is to do away with the dars go on till a named sum was expended; after which the a horizontal position, and so as to obtain a ray of tent or dark box ordinarily used under such areasame questions were to be put to the Roman Catholic sunlight on the mirror beneath the stage, we then stances. By Mr. Lane's plan the plate is fir Archbishop alone, with the same conditions; and unless, or until he might answer, their advertising was to con placed in position the slide to be photographed-coated with collodion in the open air, then it is tinue as long as any money remained. On execution with this difference, however, from the ordinary placed on a peculiar "dipper," a framework made of this will commencing, the Protestant Archbishop set mode of proceeding, that we inserted under one of varnished wood and silver. The handle of this a clerk to work examining in Bruder's" Concordantia end a small wedge tapering up to the thickness of dipper passes through the top of the dark slide, Nori Testament" every noun occurring in the nominative; a penny piece. At the eyepiece end of the tube we and the plate, after being placed on the dipper, is beginning from A, working 8 hours per day; and the average time to find and examine each, was 3 minutes. placed the camera, from which we had previously at once drawn up into the dark slide. Meanwhile the daily cost of asking his Grace as pub- removed the lens, and having excluded all light ex- of the dark slide is then fixed upon the top of a lically as the will required was £5. Presently he auswers cept that which was transmitted through the tube, vertical wooden case, containing the nitrate of question 1; but before he could answer 2 or 3, though we adjusted the size of the picture by sliding in or silver glass bath, and all the points of junction are another day would have enabled him, the sum named out the ground glass, and the focus by means of so nicely fitted that no light can reach the plate of was expended; so that the inquiry had to be transferred the rack. In this position we took the first the bath. The plate is sensitized by being pushed to the Romish prelate. He, guessing that the Protestant nd probably used the above concordance, and begun of the binocular negatives. Now removing down, dipper and all, into the nitrate of silver bath, alphabetically, thought fit to set two clerks to work and the wedge from under the end of the slide, and when it is sensitized it is drawn up again into begin contrariwise from the end, or rather from the last we transferred it to the opposite end and pro- the dark slide by the handle of the dipper. Then a possible noun (as no word containing or could ceeded as before. We thus obtained two pic- pause is made that the plate may drain itself, after answer the riddle, these letters having their numeral tures-similar, yet different. When printed from which a little sliding door closes the bottom of the meanings too high). As these clerks checked each other dark slide, so that it can be removed from the bath, tand moreover, were paid by job, instead of the truly British method, by time) their progress was at just thrice and no diffused light can reach the plate. After the rate of the Protestant's; and presently, without exposure a peculiar little jerk is given to the dark going all through the book, they enabled their master slide to dislodge the plate from the dipper, and the

and mounted on a stereoscopic slide the effect was
exceedingly beautiful; it was as if a huge model had
been prepared in a translucent material. To heighten
the effect we made a transparency on glass, and,

The bottom

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[The paper was illustrated, and the pyrometers mentioned exhibited.]

fact that this jerk has to be given seems to an ob- in chemical works as being obtained by means of from time to time, or it may be introduced into a
server to be an objectionable feature. The dis- this instrument. Thus we find it stated in Dr. furnace through a door or aperture for only a
lodged plate then rests upon the wooden bottom of Lardner's popular treatise, that cast-iron melts at a minute or two, which time suffices to obtain a
the dark slide, which is fixed over the developing temperature of 17,977 Fahr., and that iron welds at reading of the instrument. The latter is the only
bath just as it had previously been fixed over the a temperature of 21,000 Fahr., whereas it can be practicable method where the temperature to be
sensitizing bath. When the bottom of the slide is proved that the utmost temperature to be obtained measured approaches a welding heat which would
withdrawn the plate falls into the developing solu- by the combustion of carbon with a blast of atmo- in time destroy the protecting case of platinum
tion, and the process of development may be spheric air cannot exceed 4,600° Fahr., which degree or any other material; whereas, the former method
watched through pieces of orange glass fixed in the of temperature far exceeds the points of heat to be of fixed coils will be the most convenient for
wooden casing of the trough. Afterwards the pic-met with in metallurgical processes, not excepting measuring the lower temperature of drying or
ture may be taken out, washed, and fixed in day- even the melting point of mild steel, which comes annealing stoves, or of the hot blast supplied to
light. We have seen a letter from one gentleman nearest to the maximum point here indicated. blast furnaces. At iron works with a number of
who has had a set of this apparatus on trial, and he Amongst the other pyrometers that have been hot blast stoves, a protected coil may be fixed
speaks very well of it, but it requires prolonged ex-proposed from time to time is the air pyrometer, within the hot blast tube leading from each stove
perience to prove its real value. Supposing there which is limited by the melting or softening point of towards the blast furnace, and the leading wires
are no practical objections, it will be very useful as the vessel confining the air, the pyrometer by differ from each of these coils be brought into the office
tending to abolish-in landscape photography-ence of expansion of two metals which has lately where the measuring apparatus would be placed.
such inconvenient and heavy accessories as dark been brought forward in a compendious form by Mr. By such an arrangement the temperature of the
tents and dark boxes.
Gauntlet, but which cannot be relied upon beyond a blast of each stove of the furnace could be mea-
Some improvements in electrical lanterns have point approaching red heat, at which permanent sured and noted at frequent intervals by a clerk
just been made by Mr. Ladd, the optical instru- elongation of the metal set in, and a pyrometer by without leaving the office, and very perfect record
ment maker, of Regent-street. The new lamp re- contact of two dissimilar metals setting up an elec- and control be thus obtained. The correctness of
sembles a vertical cylinder in shape, and it has two tric current capable of measurement, which, how this instrument depends solely on the ratio of in-
fronts" nearly at right angles to each other, with ever, is by no means proportionately progressive crease of electrical resistance in the platinum wire,
flanges to carry lenses. When throwing a spec- with increase of temperature.
with increase of temperature. This rise is con-
trum upon a screen, electrical lanterns are never Another pyrometer has been based upon the well-siderable, the resistance being increased fourfold
placed so as to face the screen, but at an angle, and founded supposition that the specific heat of metallic by an increase of temperature from the freezing
the prisms in front of the slit bend round the rays bodies is the same at various temperatures, and point to about 3,000 Fahr. The ratio of increase
of light. Hence, by having a cylindrical lamp with that by measuring the heat of a ball of metal after is, however, not uniform, but follows a parabolic
two flanged fronts, the electric microscope may it has been exposed to the heat to be estimated, a law which I have ascertained by a series of careful
throw direct images upon the screen from the one true measure of its intensity is obtained. I have observations embodied in the table, and which
front, while the prisms may at the same time or myself constructed an instrument upon this well- form the subject of a separate communication to
afterwards throw a spectrain upon the same screen known principle, which has found considerable the Royal Society. I wish it to be understood that,
from the other front without moving the lantern. favour with ironmasters in measuring the tempera- in developing these principles, I have been
Moreover, an image of the luminous are may be ture of hot blast, and for other purposes. It con- animated solely by a desire to fill up a blank in
thrown by the one front, then its leuses may be sists of a portable vessel composed of three concen- the means at our disposal to carry on metallurgical
covered, and a spectrum of the light from the same tric cylindrical vessels of thin copper-plate, the two inquiries with such a degree of certainty as could
are be immediately exhibited by permitting the intestine spaces being filled, the inner one with not hitherto be realized, without seeking for any
rays to pass through the spectroscopic apparatus. cow-hair, and the outer one with atmospheric air, commercial reward through the Patent Office or
This lamp, then, will do the work usually done by and the two together forming an excellent barrier otherwise.
two lamps at public lectures, and much time in against loss of heat from the interior of the vessel.
adjustment of apparatus is at the same time saved A delicate mercury thermometer is fixed in the
by the speaker and his assistants. In the side of interior of the vessel, being protected by a perforated
this cylindrical lautern is fixed a little tube, with a shield, and furnished with a movable sliding scale
lens at one end and a piece of blackened ground showing pyrometer degrees, of which one is equal
The instrument is accom.
glass at the other. A small image of the luminous to 50 ordinary degrees.
carbon point is thus projected upon the ground panied by balls of copper or platinum, which are so
glass, so that the lecturer ty see that the luni- adjusted that fifty of them would be equal in ther. A that of Messrs. Davies and Yates, of Man-
nous are is in exactly the right place, this being mal capacity to an imperial pint of water. Each ball chester, which we this week illustrate, must take
a point of considerable importance in using the is perforated by a hole through which a rod is passed a prominent place. This invention, which is pa-
electric microscope. When this instrument is used in exposing the same to the action of the heat to be tented, consists in an improved "positive let-
a very slight shifting of the elevation of the arc measured. Immediately before using the instru- ting-off" and "swell motion," which, besides
throws the image off the screen. A fine horizontalment, an imperial pint of water is poured into it, other advantages, are applicable to any existing
line ruled across the ground glass serves as a guide and the pyrometer slide is so moved that its zero loom or fabric woven. In ordinary looms the
to the true position of the luminous arc. Inside point coincides with the top of the mercury column letting-off is effected by means of weights and
the lamp is a common gas jet, so that when it is in the thermometer tube. The ball is thereupon levers, which require almost constant attention
necessary in spectrum experiments to frequently exposed to the heat for two or three minutes, and and have to be altered as the diameter of the beam
change the carbon points, there is some light inside plunged into the water. The mercury will be ob- becomes less; the constant vibration of the weights
the lantern to see to work by. Altogether the new
served to rise, and the absolute temperature of the being destructive to the loom, and causing many of
lamp is a very useful instrument to the public place measured is ascertained by adding the reading the warp threads to break. The principal advan-
on the pyrometer scale, opposite the new level of the tages of this improvement in the letting-off motion
mercury, to the degrees of temperature indicated consist in it being entirely self-regulating, so that
by the thermometer before the ball was introduced. when the warp is once set it requires no attention
In using ordinary dexterity very satisfactory read- till the whole length is finished. It also acts as a
ings may be obtained with this instrument, but its vibrator in regulating the tension of the warps
application is limited to the point of heat at which during the shedding and beating home of the weft
the metal ball employed begins to deteriorate, nor shot, and by this means lengthens the duration of
can it be employed for measuring the temperature the healds and reeds. By this process a more per-
of inaccessible places.
fect 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 manufac-
turers have tested the improvements and expressed
their entire satisfaction with them, and looms fitted
with them can be seen in operation daily at the
premises of the inventor, 35, Back George-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 the improved arrangement of let-

lecturer.

One evening, 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 the 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 fit in a tube, the two ends of the prism, however, being of course inclined planes. This prism and its tube could be turned round and round by the hand of the observer. It is plain, therefore, that in one position this directvision prism aids the others and produces more dispersion; 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 are 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.
HE mercury thermometer, which enables us to
mirable precision, fails to indicate heats exceeding
the boiling point of mercury (500° Fahr.), and
although many attempts have been made to produce
a reliable high temperature thermometer (or pyro-
meter) 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 first 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 pro-
portionate to the intensity of the heat to which the
ball of fire-clay had been exposed. The error in-
volved in this supposition becomes at once apparent
if we consider that the shrinkage of the ball is
caused by the expulsion of water of hydration which
must necessarily take place chiefly at one particular
temperature. It is proved, moreover, by the very
discordant and, in fact, impossible results, recorded

Paper read before the Iron and Steel Institute at
he meeting in South Wales, September 6, 1870.

It has been my 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 the practical metallurgist. It is based upon the peculiar properties of the pure metals 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, upon 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 temperature only of wire are brought out 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 Wheatstone or other methods are dispensed with, and a reading in degrees of a 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 measuring instrument, including the platinam wire of the pyrometer, produces a deflection of the galvanoineter needle. These degrees do not themselves express the temperature, but the temperature they represent is expressed by a table of refer ence, which accompanies each instrument. The pyrometer coil itself, with its protecting casing, may either be fixed permanently at points, the temperature of which ought to be ascertained

IMPROVEMENTS IN POWER LOOMS. recent improvements looms

ting-off apparatus. of the
Fig. 2 represents a transverse
ments applied, showing the position of the appara-
tus when the
home the weft shot.
sley" is on; its front centre beating
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.

the levers 61 61, supported by the bracket secured
In these figures, a is a rod forming the fulcrum of
to the framing c of the loom immediately above the
flanges of the warp beam d.
levers bb carry or support a rod e passing under
The upper or shorter
and supporting the warp threads, as they pass from
the beam d of the lower or longer levers b1b1, carry-
ing a rod that lies against the yarn of the beam
and passes under the last fold or lap of the warp
ends. The upper levers carrying the rod e are sup-
plied with projecting brackets g g which support
adjusting screws and nuts hh. The lower end of
the screw underneath the bracket g is connected to
a rope or chain k, which passes first around the
drag pulley of the warp beam, then under a carrier
pulley / connected to the lower frame of the loom
below the warp beam; after which it passes onward

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continued until the required tension of the v obtained. When the tension is obtained and loom in action, the beating up of the closing in the weft shot (at which time the on its front centre as shown at Fig. 2) ward the top rod e, thereby causing the, b to exert a pressure upon the warp thesi gives an excess of tension to the same ty beating home the weft shot and effects the cloth under manufacture. On the sley (Fig. 3) the upper rod or bar e inclive by reason of the action of the spring is medium of the ropes or chains Ek, then the lower rod f against the beam to bec so as to reduce its tension upon the way taneously with which the ropes or chains the drag pulleys of the beam are also eas allows the necessary quantity of yarn to b easily from the warp beam sufficient for i pick, and the healds to open the shed with or tension upon the yarn. Again, as the d of the beam becomes reduced with the dele yarn thereform, the lower tension rod fin with the passing warp threads gradually the beam, thereby effecting during the de the yarn a proportionate reduction of tension spring forming the coupling between the end e ropes or chains kk. When it is desired to let's the warps, a temporary release is given to them through the medium of the lever a, which, pulled over into a position the reverse of that sh at Fig. 1, relieves the spring ; the original tenso being readily obtained on recommencing wearing 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 sm struction 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-box independently. Fig. 5 represents a plan view of the shuttle-box showing the position of the swell in relation thereto. Fig. 6 represents another modif cation of the swell and its supporting brackets 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 the brackets or arms e secured to the stop rod : the distance the swell d is allowed to protrade in the shuttle-box g is regulated by the set screws & L Thus 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.

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SCIENTIFIC SOCIETIES.

THE IRON AND STEEL INSTITUTE.
HE second provincial meeting of the Iron and

T 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 Alleyne, Bart., R. Fothergill, M.P., W. S. Roden, M.P., E. M. Richards, 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 preceedings by alluding to the pleasure with which the members must turn from the contemplation of the scenes that have recently taken place on the conf nent to the matters to be considered by the me ing. A report was submitted by the council which they stated that arrangements had be made for publishing, in connection with the int tute, a journal, in which, besides the usual pel ings of the institute, all matters connected with the manufacture of iron and steel at home and abroad, will be fully reported. The council re commended 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 Devonshire. Mr. Bessemer acknowledged the compliment, and said his best endeavours should be given to furthering the objects of the institution, and he hoped to fulfil his duties, if not with entire satisfaction to himself, at least without injury to the insti tution.

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 36,000 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 at the western portion of the field it is anthracitic.

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The argillaceous iron ores are abundant and good. They form an aggregate thickness of 60in. 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 64 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 9in. per yard, while on the south it varies from 9in. to 12in., 15in. 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 an 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 refer ence 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 in the Bessemer process the silicon is not removed before the carbon as in the puddling and refinery process es, 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 Rails."

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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.

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dips 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 dens for animals and retreats for mankind. One remarkable feature in the Cheddar Pass is that on one side the road the cliffs are absolutely perpendicular, while the other is sloping, and covered by a considerable quantity of débris. 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 Mendip range. On the conclusion of the address the company returned to the foot 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 he 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 wire.

MAIDSTONE AND MID-KENT NATURAL HISTORY SOCIETY.

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. In 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 made his houses on one side of the street-not back to back, as the bee did, and he 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, Réaumur, 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 concluded 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 neuters. 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.

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 regard to the internal construction of gas-meters, although every house, office, and workshop in mechanical communities was supplied with the

same.

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 AT a recent meeting of this society, the Rev. the subjects which stood over from last meeting Walter Mitchell, vice-president of the Philoso-viz., Action and Description of the Ejector phical Society of Great Britain, gave an address Condensor; Clayton's Patent Scraper; The Pracupon "The Geometrical Structure of the Hive Bees' ticability of the Birmingham Patent Safe and Cell." He said he had adopted the above title as Sure Sectional Wrought-iron Boiler; how it is for there were 250 different species of bees in this Steam power, for comparative consumption of country, not one of which possessed the geometrical coal, &c. 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 drones, and several thousand neuters or 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, the celebrated naturalist, who, on dissect ing a bee, found that in the abdomen there were certain small bags containing a white substance, which, on barning it in a candle, proved to be

EXETER NATURALISTS' CLUB. THE Exeter naturalists recently visited the Ched-working bees. He then pointed out that a bee on a dar Pass, in the county of Somerset, where Mr. W. W. Stoddart, F.C.S., F.G.S., delivered an adThe 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 that 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 bods 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 Mon

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 Clegg, 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 a copy of the preceding one, a special committee who investigated the charge gave their verdict in favour of Mr. Malam, by awarding him their gold medal for his invention of a gas meter, new, ingenious, superior to all 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 others having glass fronts-the merits and defects of each 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 disenssion on the subject followed, in which the description of a recently invented hydro-carburetted gas lamp was given.

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