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COMBINED PUNCHING, SHEARING, UPSETTING, AND STRETCHING MACHINE.

keen the tiro (гота »lipping; there is (1*0 a movable block N, »МЛ ha» a similar projection O, and which Is al»o provided -with teeth in the »ame manner as the other. The movable block N has »Jooth Pon the under aide working down into the cam B, and is moved in the operation of shrinking a lire by the hand lever 1. Upon each of the blocks L and 5 is a toothed eccentric y. for the purpose of holding the tire while the block N ia betng carried towards the block L. The operation of stretching a tire is performed by reversing' «be eccentric* Q. and carrying the lever tie other way.

The punch socket R is connected to the earn В by the pin S, ami passes through the guide T, the die being confined in the main frame A. The operation of "gnmming." er rutting between the teeth of saws, is performed by a punch and die made especially for that parpóse. A guide V is cast on the main frame A, so as to keep the lever D from being forced off in the operation of cutting. Finally, a concave projection W, which is east on the main frame A. project» about 3in., and a corresponding convex projection Xis cast on the lever D. These paru are used for bending iron into any lenuired form, and they form, according to Eugi***«»$, a useful addition to a very useful machine.

B. G.

an ordinary evil, but as, obviously, this cannot be done by any direct action of gearing, since the bobbins require avarying spied, and the spindles and rollers an unvarylng.one, some sort of mechanical contrivance must Intervene betwixt the gearing of the spindles and the bobbins, that will give to the bobbins the varying speed they require with tho necessary truthfulness. This contrivance, then, is the sun and planet wheels, regulated by the cones and strap-rack. Let "Excelsior" look at the sketch, and he will see that the spindles, bobbins, and rollers are all driven by positive gears from the driving shaft. The wheel I (sun wheel) gives motiou to the wheel 2 (Internal wheel), this carries it to 4 (boss wheel), and so on it goes to the bobbins, 5. Now comes the disc wheel 3, which carries the internal wheel; if this wheel bo held stationary, the velocities of 1. 2, and 4 must evidently be equal, but, on the other hand, if motion be given to the disc wheel 3 in an opposite direction to that of the sun wheel 1, then the internal wheel will be driven Just as much faster, so also the "boss wheel" 4, and the bobbins. This opposite direction is given to the disc

COTTON SPINNING. Si»,— As no one has taken the trouble to enlighten "Excelsior," p. 1927, March 4, I will, with your permission, endeavour to do so. He asks for an explanation of the sun and planet wheels, cone, aud reversing motion ofJHiggins's roving frame. The object of the cone, or what is better, cones, is to give to the bobbins a constant circumferential speed, or velocity of periphery, so that they may " lap" up tbo roving yarn at tbe seme rate as the rollers deliver it, ав the diameter of Che bobbins is constantly increasing from "empty" to *' fuIL" I suppose he will know that the yarn is "lapped " around the bobbins by the " Üye ;" if so. be will see tl/ut if the bobbins "lead" the flys, as tbey ore now generally made to do, their speed of revolution must be retarded in proportion as their diameter is increased, but ii they lap it up by "drogitag" behind tbe fly», then their speed must be increased in the same ratio. Now a» the cones have their extremes, in proportion ;to the bobbin, empty sod full, I dare aay *' Excelsior " has wondered what the sun and planet wheels were for, as at tlrst sight it appear» that a properly adjusted .notion might be «Tientothe bobbins directly from the cones—i.e., by the eso» being made to drive the bobbins, and their »p«d adjusted by a "strap rack." However, a little more consideration, or what will teach a man far more poMUvely, a, little experience, will soon show that If the spe*a of the bobbins be not very exaetly and positively idjusted to that of the rollers, the quality the roving will suffer, on one hand from attenuation, on the о!Ъег from "lagging" around the fly-top. it was formerly a matter of great difficulty to regulate the spe^d of the bobbins of the roving frame, as it was done by what was called a "differential rack and frfefJon-p/ate." the results of the adjustments being generally rather too differential. But this difficulty was at fast overcome by the Introduction of tbe "cone.'aod fcon and planet wheels," the working and object of which I will now try to make "XxeeUior" understand. He will see that If motion could he given by positive gearing to the spindles, bobbins, and rollers from one strap, the irregularities oí speed from "slipping"would be only

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wheel when the bobbins " lap up" by " leading." but when they do so by "dragging, thou the direction of tho disc is tho same as that of the sun wheel, and the result is a subtraction of velocity from the internal wheel, Ac. Suppose the rollers "turn out" 31n. of yarn while the spindle» make 9 revolutions. If the bobbins be :lin. in circumference it is evident they will require to make 10 revolutions in the same time as the spindles make II, in order that they may lap up tho 3ln. of yarn delivered from the rollers. Supposo this to be tho condition, then, that is required at the commencement of the "set," and that the " disc wheel" gives this one extra turn to the bobbins, either by one revolution of its own, or whatever part of one the arrangementof gears may require. With the couc strap driving at the fastest end of the cone, It will be evident to " Excelsior," If the eistrem.ee of the cones, as I eaid before, correspond to those of the bobbin empty aud full, that the speed of the bobbin can be regulated with greatest nicety by causing the strap to move forward a proper distance for each layer of yarn that adds to the diameter of the bobbin, as the real weight of driving

the bobbin is given directly by the gears 1, 2, and 4 from the driving shaft, so that the small amount ol power required from the cone strap by this arrangement renders it as near a positive in its action as needs be. The reversing motion comes from the sume source. It regulates the up and down motion of the " lifter,' upon which the bobbins rest, in order that tho yarn, may be collcd'upon them in a proper manner—i.e., the coils laid side by вЫс. The changes of direction are given by the bevel wheels 7, the one being thrown oui of gear as the other is thrown in, and is brought about, by means of a lever, one end o£ which is lifted up or pressed down by a slotted fixture attached to the "lifter," which is also connected in a suitable manner to the strap rock, so that its fulcrum is brought nearer the end at every change, and by this means it causes the " lifter's" direction to be changed a little earlier for every layer of yarn that goes on tho bobbins, and. so gives tho required taper to the ends. I hope now that 1 have given "Excelsior" such information a» will enable him after a little further inspection of the frame itself, whilst working, to understand that very ingenious device, the sun and planet motion. I have tried to be as plain as I could, so that what I have sain' may be understood by the numerous youug cotton workers who are readers of our wonderful Mechanic. and if It meets with the approbation of our Editor, I1 will gladly add a " few bricks" to our "institution" for the benefit of those who seek such Information as I can give, so that faotory lads may not have to complain of the paucity of matter lu the Mechanic in which they can take an especial Interest. With respeei to "Excelsior's" last question, I know no such work. I should just like to say in conclus! n that 1 think the space taken up sometimes by "straw splitting," such as that a week or two ago about what a " devil " Is or Isn't, would bo much better filled up by charity, as all the writers were to some extent bolb right and wrong, and the mere locel name of a machine dees not effect its proper working, that I am aware of. E- Slateu, Burnley.

TO MILLERS. Sir,—I will endeavour to review this correspondence as briefly as possible. Some few weeks ngo I lorwarded to you, Sir, a diagram of a modification of tbe universa!, joiut, which is a decided improvement en the old plan, and le!t it at your option to insert it in the English Mechanic fur the benefit of my brother readers, or otherwise conelgn it to the waste-paper basket. However, it made its appearance in due time, under thesomewhat indefinite heading, "Something New for Millers." 1 have no fault to find with this, though they are not my words, and not what I intended it should be called. The name I gave it was "Universal' Balanco Rynd," accompanying which was also forwarded a few words descriptivo of ite construction. This meets the eye oi Mr. Sharpe. who writes to say that he has had the same working In his mill since 185(1, and proceeds to give а "vuguo " description of what now r»nu'es to be something else, respectiug which I wrote for an explanation, and how we were to reconcile those contradictory statements. This, to all appearance, he is unable to do, but resorts to abuse and misrepresentation. 1 never said that 1 was the inventor of the universal Joint as such, b :i of the same as per diagram; and auy ordinary intellect would have so understood it. If the description given was ml sufficiently clear to him, surely tbo diagram ought to be. He says that the only part that 1 rau lay claim to is the outward ring. Let me tell him I never said I

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«tul, because I knew perfectly well that it was in use toux before tu England and Scotland, and be says it is i-nmrnon fn Ireland, too, the stone being built around it: so :.ilко may mine be ¡ and does not occupy the eye of the stone any more than his. He now proceeds to answer, unwittingly, my query, by describing his scheme, which la »imply two separate boxee let into the sides of the eye of the stone, which must be cut away to admit them; and this be says is an improvement upon the solid ring, bitiU in, which he also saya <1оен away with tbe necessity of making one of the rings oval. Just so, and le tantamount to what I expected, wliieh goes directly to prove the fallacy of hie ¡insertions. For why should ne make a ring ovaldf Liiere were no necessity for it? Be tries to overeóme this by saying that the sliding steps are common to Tcmpleogue, while the oval, or unnecessary shape, is outlined to himself, probably In the shape of a crony. And oí course, as he tayK, oar motives for adapting this shape are quite different. It la, therefore, quite evident that he knows nothing about the utility of my scheme or invention, to forma correct judgment.

Твое, к Vans. 'We have thought best to draw our pen through роше personal remarks In Mr. Evans' letter, to render unnecessary a keen reply from Mr. Sharpe.]

Sir,—In the English Mechanic (No. 264) there are two replies to mv letter in No. 262¿en " Millstone Balancing." Mr. Sharpe supports ray opinion; I thank him for his reply. I also thank Mr. Evans for his criticism of my ''notions." He is the*first that has attempted to explain tho matter to me. 1 have asked many millers for their opinion, but till now could get m» (iirect reply. I honestly аявигс Mr. Evans if I do not see with his eye«, my blindness is tbe result not of obstinacy, but misfortune—or ignorance, if he think proper *o to term ÍU

I try, and have long tried, to take Mr. Evans' view of millstone balancing, but the more I study the subject, and the more experience I gee, the more sceptical I become; for I too have ideas—probably very vague ones«—of something called gravitation, centrifugal force, &c, and of the unequal distribution oí the former over a millstone. I have had considerable experience aa a millstone builder, and have new backed, put in fresh burrs, and broken up many a stone; so am slightly acquainted with a millstone's composition, Ac.

I have seen Mr. Smith 's diagram (referred to), but confesa I am too unenlightened to understand why, when a millstone's gravitation has been equalised when standing, it should be disturbed when running. J t seems to me the faster a stone rune, the, greater tendency it should have to equalise its gravitation.

Mr. Evans objects to my " notion" that a level bedstone has anything to do with balancing. 1 acknowledge when giving a running balance it would not matter were the bedstone 45 degrees out of level, or vertical, or away altogether, providing the spindle was hold steady and a rest furnished for the chip; but will he say it is not necessary- for a standing balance? If it is not, then I Jam indeed under a delusion, and bave been these last 23 years.

As to millers looking to the face of the stone for the fault, could he tell, if a stone had a good standing balance, if it had a high side to it?

I have had the opportunity in many mills to test my ;* notion," and, as I remarked in my first letter, have invariably found when a stone's standing and running balauce did not coincide, that either face, level, Irons, or cogs were untrue. Either of the above fault* would •r-ause a dragging, or apparent dragging, causing a back-laah, and disturbing the neck.

With respect to length of splndlo disturbing the neck, aa asserted by some of your correspondents, I will offer no opinion, but merely say I have one stone lüin. thick at eye. Hin. at skirt, on "centre irons," with the pivot 8Jin. from the face of tho stone, and ¡mother pair on faulty "universal irons," 13|ln. at eye. 1Ц1п. at skirt, with cups ouly 2j|tn. from face. Each pair works well. There is but little difference in tkeir speed of grinding and per centage.

1 suppose Mr. Evans does not pretend to lay claim to tho invention of the " universal irons," but their oval form and set screws. His outside ring has been in use some years; so has that described by Mr. Sharpe.'

With respect to your correspondent "Charles's" balance, good aa it might be, I believe it got the inventor of it into trouble, he having been prosecuted for infringing on tho rights of Messrs. Clarke and Dunham. 1 think the above patentees will tell us the "sliding " or " running " balance Is their property, and any one using a substitute for theirs is Infringing their patent.

But to return to my "notion." Until I get more light, 1 must still run the risk of being thought Ignorant and unpractical by holding to the opinion that if the face of a >tone be true, the bedstone level, the i rone and pitch of cogs correct, a "standing" and •' running" balance are the same; and if the above conditions are not observed, they are not the same.

A Stoneman.

Sin,—Without doubting Thomas Evans* statement respecting the capabilities of the '* patent flour machine" he refers to, perhaps It may not be uninteresting to some of your readers to endeavour to explain the .probable cause of the difference of the «quantity dressed by it and mine.

Ill» machine dressed through 5 sheets of wire, mine only had 3J (the half was seldom used). Ho took 15ft. •tf flour out of 2Uft. of meal, I only took 12¿ft. His M-ichine had 6in. to the footfall, and therefore had ta t<i. driven at 620 revolutions per minute, mine only went at 400, so that when the speed, the power, the length of wire devoted to flnc flour, number of wire, and allowance for a little exaggeration taken intocon,-ulcr:iiton, I don't think the modest amount of tí sacks ;»t')' hour will appear so insignificant aa at first sight. With reference to the relative advantages of silk t*. wire, I should recommend the silk less on account of Its superior work than lor its saving of flour, wear and fe.*r. and attendance. The power required fora wire rniu-hine such as Thos. Evan* describes would exceed Hi p., while the power the silk requires id hardly ob

servable. I have improved French flour by dressing it through wire, yet for the above reasons I prefer the silk, but should anything occur to necessitate a return to the wire, the patent machine Is the last I would adopt. • Jas. S&anrE.

Л THEORY OF THE CAUSE OF THE TIDES.

Sib,—According to Newton, it is of the principle of gravitation that two globes placed at a distance from «ach other, stationary, but free to move, must with an Increasing speed move to their common centre of gravity; but if propelled In a direction not in line with their commet centre of gravity, they will each revolve round that centre of gravity in a certain period of time. I propose that the earth being about fifty times greater in bulk and density than the moon, their common centre of gravity will be within the maee of the earth, and at a certain distance from its centre; that the earth revolve» on this centre of gravity.or combined axis ia tbe наше period of time ae the moon, about t wen t у-eight day*; that the earth, revolving on thJe combined axis, ha« an eccentric motion, and that the part of tbe earth's surface farthest from the moon, and in line* with the two centres, i« aabject to an Increase of centrifugal force that thé demie matter of the earth, in its revolution on its central axle, is not at liberty to accommodate itself to; that it Is otherwise with the air and water; that the waters are raised by this centrifugal force In a ridge or wave on or near the equator, at that point most distant from the moon, which will also bo the port of the earth's equator most distant from the combined axis; that this force rn excess only extends to a few degrees on either aide of the equator; that tbe open waters outside of these lines towards tho poles merely obey the law of tho displacement of fluids flowing towards the equator, to temporarily occupy the pluce of that raised In a ridge or wave on or near the equator by the excess of centrifugal force produced by the eccentric revolution of the earth on its combined axis; so that, n lake outside of these lines, or a large bay with Its inlet towards the nearest pole, would not be affected by the force that produces the ridge or wave on or near the equator, or the flow that the open waters are subject to, and so would have no tide; that the revolution of the earth on Its central axis once in about twenty-four hours will cause every part of Us equator to come under tho influence of this excess of force produced by its eccentric revolution on its combined axis in that period of time. So that with the moon's attraction in the opposite direction, we have the ebb and How of the tide twice in about twenty-four hour.-*, omitting secondary and local interferences.

G. H. Ogilvy, Birmingham.

THE EARTH'S ROTATION. Sib,—With your kind permission I will make one or two remarks on a letter appearing on p. 89, on the above subject, signed by John Boardsley. Now although I can lay claim to no scientific attainments, yet ray own common senst seems to rae to detect some very fallacious reasoning on tho part of the writer of the letter referred to, it' I am correct fn presuming that Mr. tíeardsley makes centrifugal foret a basis for disputing the fact of the earth1» revolution on Its axis, in the first place, I beg to submit that Mr. Heardsley's ideas of "cen trlfugal force" are, to say tho least of it, very vague; he appears to think that objects on the earth's equator, because they have a surface speed of 17 miles or so, per minuto, must, therefore, have a tremendous tendency te fly off. Now with all due deference to the "godfather," I think the very term " centrifugal " is calculated to mutend, for this reason—an object projected from a surface In rapid rotation, does not pursue a direction of flight directly in a line with the centre of the body from which it has taken its departure. On the contrary, the line of flight, if produced backwards, as it were, would, I Imaßine, be found to be a tangent touching the circumference of the rotating mass, and it takes this direction merely in obedience to the law of nature, that bodies set In motion in auy given direction endeavour to continue their motion in that same direction. Now my idea with regard to objects on tho equator is this (and I 'invite anyone to administer to mc a good hearty whack if I am talking nonsense), that they —the objects—pursuing a surface speed of 17 miles a minute, have no more tendency to dy off from centrifugal force than would little Iron filings on thesurface of a globe of magnetised iron, say 8i'L diameter, revolving on Its axis onco In 24 hours. The magnetism is of course to represent gravity ; this globe would have a surface speed at its equator of about 1ft. per hour, which may be taken to represent the 1UO0 miles traversed by a point on our earth's equator ; tbe arc of the circle described would be Identical in each case. Now the 24th of a circle, when drawn on paper, looks like a very slight deviation from a straight line ; it is just as slight a deviation in the case of the earth, and does Mr. BeardMley mean to say that a body would have any perceptible tendency to fly off from "centrifugal force " when, after an hour's flight. It had only departed from a straight line by so email a curve as this arc represents? I will bring forward another case for Sir. Boardsley's consideration. Conceive а huge locomotive, with driving wheels 100ft. diameter, cylinders, boiler, and gauge of rails to match—fancy this monster tearing along due north and south (I men* tion this direction that it may not interfere with the earth's motion) on a line of rails laid, say 6ft. above sea level all the way from pole to pole, rushing along at a speed of 1000 miles an hour, does Mr. Beardsley for a moment think that such a speed would cause the engine to launch Itself into space from centrifugal force? I can scarcely think he would form such an opinion; and yet this engine would be travelling over the same curve, pursuing a precisely similar fine of flight, at precisely the same в peed as objects at rest on our equator ; In fact, the earth s revolution Isonly comparatively rapid because we (little insignificant atoms) are uot accustomed to view in oureveryday life movements ou such a gigantic scale, but looking at the earth simply as a globe, Its motion Is in reality very

Blow iudeed, and quite Incapable of any perceptible tendency to cost bod Tes off by Centrifugal force ; at least, this ia my opinion, and I am open to correction, and shall be only too glad if anyone will kindly show me where my judgment fa at fault

I cannot take up nay more of your veleeble *pace in discussing the other portions of Mr. Beardsley's letter, relative to the wind, Ac., bat it appears to вое to be well, never mind. С R Q., Hants.

THE BELTS OF JUPITER,

Sir,—As Mr. Grover expresses a wish not to eJKP into a (long discussion en the above subject, I assure him thaul also am quite willing that it should be cut short as quickly as possible; but as his letter is such a string of misconception, I feel bound again to reply. In the tiret place, Mr. Grover's quotation from ray letteras to "delicate gradations," «fee, is a mistake when applied to light and shade; 1 applied that term to colour only. The words I used were, "broad mwssex *' of light and shade, which are quite different things, and which 1 believe are affected relatively and proportionally the same with every- sized aperture; but Mr. Grover implies that the reverse of this is abundantly proved by the amount of detail which a large aperture reveals when compared with a small aperture. I really cannot see how this affects the question of broad masses of light and shade. Ás to the professed impossibility of getting pigments suitable to express planetary marking«. Mr. G. brings an instance to support his argument, of a lily, which, though really a white flower, had to be painted grey to* x pre es shadow, in what way this supporta his argument as to the impossibility of gutting pigments pure and bright enough I am at a los« to conceive, auch an instance evidently does not tones the point at issue. Again. Mr. Grover says: "Mr. Purklss thinks I am in error In stating that Mr. Browning's drawing is overcolonred.'* Certainly not. Had Mr. G. said so at first, I should have perfectly agreed with him ; but he did not say so, but remarked that the drawing referred to was tfío vhi<i in colour. The term "overcolonred" implies that there Is too much colour, or that it is too heavily coloured; whereas tlruLUy Implies brilliancy and light Mr. Grover may perhaps think I am splitting hairs, but such distinction* are absolutely necessary to prevent misunderstanding. My remarks with reference to 3Ir. Denning's letter therefore do not, that i am aware of, offer any contradictions. The next paragraph contains a singular misconception. Could Mr. Grover really suppose that I ventured for one moment to compare a painted sunset with a real sunset? Such would evidence a degree of insanity which I hope I do not possess at present. Truly, I spoke of a sky, and I spoke of a landscape, but only as they might exist on canvas, and so could be compared with each other; and it still remains for Mr. Grover to justify his plea for the need of exaggeration by the simile I then used. In the concluding paragraph Mr. Grover descends to personalities, which certainly do not lend any dignity to his preceding remarks. Does he expect me to blow my own trumpet as a draughtsman, or to spout about tbe performance ot my mirrors? However, for the general satisfaction of your readers, some of those gentlemen for whom I am now making specula (thanks to the popes of the Mechanic) will perhaps shortly be prepared to Jet you know the merits or demerits of my work, which they have my free permission to do -, ьш! then Mr. Grover can judge for himself. W. Рспкме.

THE REPUTED FIGURE AXD MOTIOKS OF THE EARTH.—THE EARTH'S ROTATION.

Sir,—I am aware that it Is held that as the motion is steady, this (the centrifugal force In connection with the earth's rotation) becomes possible, because ** motion without shaking is as сачу as rest. We carry the air with us, as in a railway carriage, and therefore feel no wind."* I must confess I never saw lamer reasoning, ora more complete failure to give a reasonable explanation to a theory. , No one, I think, will dispute the fact that "motion without shaking" is as easy as rest" under the condition named; but how is it made to appear that we, on the earth's surface, exposed to Its rotation, are in a similar position to being in n railway carriage, where, of course, the frame and substance of the carriage protect us from the effects of the rash through tho air?

If our author will take his seat outside a i ail way carriage, on an express train proceeding at a speed of 00 miles per hour, he will find he Is more exposed tbat¡ Is desirable, and he will then be able to form soe» idea of the sensation he would experience if whirled throngh space at a speed 17 times as fast. On the other hand, if the air carried with us is meant tho air inside the carriage only, where Is the comparison ( In the one cose we are exposed outside- a rotating sphere, in the other boxed up in a carriage.

Also if he will put water on to a flywheel, connected with any piece of machinery in motion, indoor«, and under the same conditions as it inside a railway- carriage, ho will find the water thrown off in proportion to the size and speed of the wheel, which proves the assertion to be entirely unfounded in fact.

Again, if there is any such thing as a truly vertical position for objects on the earth's surface, how is it that if the earth is globular that such a thing ae a vertical line is to be found every where, as we approach the poles, and also at the equator? The answer, I am aware, is dependent upon the theory of gravity, producing verticsl lines as straight ones, pointing to the centre of the earth, and that force Is roquired to divert tho motion of anything from such Hue. Миг what proof have we that a really vertical line has no existence? lam not aware of a single argument in proof of this, except that of necessity (gravity >, for if a plumb line be let fall at tbe equator, aud the true vertical linâ pointa to tbe centre of tbe earth, would It not require a greater force to form a comet and straight line at one portion of the H hours (it takes to form this rotation) than at the other portion of the same 24 hours Î

Astronomers agree aa to the existence of a zenith,

* "Astronomy without Mathematics," расе гг.

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or place directly overhead ; or. in other words, a true perpendicular. This zenith, or perpendicular, from the centre of the earth, they give, an at a point to the left of the North Pole, aa it would bo shown in a diagram. Now, from this wo conclude, that by a universal law there must be a correct horizontal to all perpendiculars, and which are at exactly right angles the one to the other—and it is also an established fact, that all bodies, or everything that has weight, and is unobstructed, bus a tendency to fail in a straight line downwards from its point of suspension, if not infl«enced by attraction or force. I am aware that we'ght has been, and is generally described as the •■ measure of force," but to this definition I object, as it depends solely for proof on the theory of grarltative attraction ; a theory (so far as f know) which has not a single argument (confirmed by positive fact) for its support.

The true vertical line is said to be from the point of suspension c, or in a straight line for the centre, as in the annexed diagram (or p) that thcearth's rotation tauses any body let fall at A to fall somewhat towards D, to the said centre f, and the experiments of Dr.

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Hook, Guglierslal, and of Benzenberg, and with all the care which the last-named philosopher brought to bear, he found a deviation in his experiments on falling bodies, towards all four points of the compass, so that he had to be satisfied with a "balance of deviation," a term, and a fact, which plainly shows that some other principle than the earth's rotation had control over these balls through 215(1. of vertical space.

Now we will put aside as much as possible the mathematical terms which are puzzling to some readers, and show that this speed of 17 miles per minute, which the surface of the earth porforms during its rotation, being close upon 1500ft. In one second of time, is simply incredible; becanse when we find thatabody falling from a posltiou of rest falls through 16ft. in ono second of time, this "balance of deviation" of a few Una to the east, is mora incredible still; for if we divide the height of the tower i'i ;."»ft.) by rule, we shall find that the ball would occupy nearly 4 seconds in fulling, and, consequently, that the earth should have pasted in that time for the space of 5'joo to 8000ft. from the true vertical, past towards the east. So that it is not a question of lines, but of thousands of feet It may be said that the speed at which the earth rotates will cause the ball to be carried with it to a great extent, reducing the ■ inference of distance traversed during the * seconds. Hut it this rotation is a fact, and this forward force applicable to the falling ball, why does it not bound onwards in the same direction as the rotation, the same as any body will do let fall from a railway train? The question of the body's falling down a mine, for such a depth, under such circumstances, Is simply absurd.

1 come now to consider the diurnal motion of the Hun, as a proof of the spherical figure of the earth. I might easily set out by giving a few diagrams, proving that the earth is a vast plain. I do not advance this assertion as true. I do not argue that the earth is a vast irregular surface, behind which the sun rises and sets. What I have to say is, that the apparently convex surface of our world is not owing to any real convexity of the surface, but to optical illusion, or the principle of vision, combined with the refraction of the atmosphere; indeed, these two principles arc the foundation of all our errors as to parallax, measure, and distance, the first and fundamental error upon which a host of others have been grafted.

Now, as to the proof that the earth really moves, the simplo fact that a small rotating semicircle • may be made to keep pace with the sun, and to cast a uniform shadow, is no proof at all. It of course is altered and moved, uutil the different parts arc adjusted, so aa to show their exact relation and position one to another, and then the principle is said to be complete by way of Illustration, whereas the construction, and the position intended to be illustrated, may be as fereign to each other as possible. In proof of this I may say that Mr. Proctor admits Ikxclisii Mechanic, Vol x,\p. 598) the system of Tycho Brabe may be Illustrated just as easily. This being so, I surely shall not be called upon to enlarge much upon this part of the subject.

We will then at once proceed to Inquire Into the principles which actually exists, and which may throw «ome light upon the cause of light and darkness, and Illustrate the subject in hand. Mr. Hampden has offered to stake £500 on the proof of the convexity of a river, a canal, Ac, and which you notice in your present volume, pages 70 and 95. I con regard this matter in no other light than as truly extraordinary that man should be so wedded to system, as to be blind u proof they witness nearly every day of their lives. 'hejiu I »oan b8 abbj to ,m,v(, triat the apparent greater height of an object, in the centre of 0 miles of water, than otjects at either end of this distance, is not owing at all to convexity, but to an entirely different principle in nature, but which principle does not appear to be universal.

It seems almost incredible that philosophers will not call things by their right names. It they had said visual Illusion so much, whether it be by refraction "r otherwise, I eould have understood them. Any plou(.»hboy can testify to the changeable appearance In width of the land he has marked out, snd not quite finished lit the same is of equal tc-idth throwjhmit. When he is at the end A, Fig. t, the part unfinished, appears as in the figure at B, and when he is at B the end A appears narrowest, and so on; the end he stands

• Mr. Proctor, in English Mechanic, Vol. X , page 1*4.

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of rails. A town street assumes the same appearance, Inlrralli/ and vertically; Indeed, the principle Is almost universal.

Although this principle will be more fully dealt with when I come to the question of piirallitx, I may say here that the rising aud setting sun and moon, and the appearance attending their joarney through space, aio Illustrated by a consideration of this principle of visual illusion, which we may define as the apparent lateral and vertical contraction of space in distance, or, scientifically, lateral and vertical perspective.

It has commonly been held that the earth is speeding round the sun with Inconceivable velocity, and that the appearance of a rising and setting sun could not be accounted for in any other way than by the rotation of the earth about its axis.

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We will snppose A B to be a plain on the earth's surface, aud M the moon, and s .*' g" the rising sun at apparently different altitudes, and we will suppose, for the sake of easy illustration, ibat the observer stands at A, and that n and M are at equal angles to the right and left, and supposing a t' >f and M are at equal height, the question arises, would the sun «'appear as shown in the diagram, before the vanishing point Is marked? 1 contend that it would, for the sirup'.o reason that the visloual illusion, called in all engineering work* "curvature "(but which is neither more nor leas than optical deception), accounts for it.

There is in all sights a vanishing point, or a convergingof the rays to a point at various distances, and we will suppose Din the above figure to be the vanishing point of a person stationed at A. This point, thon, will be the observer's horizon, because of the converging of the bottom and top rays to a point at D, and fixes the object above the horizon, at an apparently less altitude than It is in reality, and if we carry a straight line from D to s" we shall witness a rising sun, and vice versa a setting sun.

I will take the table of curvature as It stands in Baker's" Land and Engineering Surveying," aud by rule, which agrees (refraction deducted)'with the late experiments, and apply It to Fig. 3. The difference in altitude, given aa the different between the '* ap

Sarent and true level," supposing «' to be 30 miles istant from A, will bo SoeTt. Or I) will be 600ft. above the line A It, and supposing »* to be CO miles distant, the difference between the apparent and true level will be2400ft. Or if we suit the altitude to the dlstance.it will vanish entirely, because it is below the observer's horizon D, really in the same altitude as a. So that it is plain that instead of curvature (considering the line c B to be a perfectly true level), that an object is really higher than H ajypears to be when beyond the observer's horizon. But when within the range of vision, objects appear higher than they really are, as is shown by the apparently higher position of the middle object viewed from either end, in the experiments In connection with Mr. Hampden's challenge. That is, from A to D objects apparently rise, but when tho limit of vision is reached, any independent object beyond it appears from A to be lower than it really is. John Beaudslxt.

(To be continued.)

[We admit we owe an apology to many of onr readers for devoting space to letters like the above, and if similar arguments and illustrations were not used nightly in lectures, as we said last week in our'1 Notices to Correspondents," by " Parallaxes, enthusiasts, and charlatans," we would not do so. These lectures, as Mr. Dyer, la his little work on the "Form of tho Earth," say*, are unsettling the minds ofjmany people who have not studied the subject. We therefore give Mr. Beardsley space, so that he may be triumphantly answered.—Ed. E. M.J

TIME.

Sir,—Absence from home has prevented an earlier acknowledgment of the reply which "F.K.A.S." has kindly given (p. 80) to my query No. 2425.

The question proposed was, how to obtain G. M. T. from local S. T., at a place whoso longitude Is 8m. 7s. West: having regard to the following " explanation" of the Nautical Almanac. "If the place of observation be not on the meridian of Greenwich, the Hideral time " (i.e., at G. M. N.) " must be corrected by the addition of i) 8560s. for each hour of west longitude, but by its subtraction if east."

Where longitude is expressed in time, I have understood it to mean sidereal time, at the rate of 15° for one hour. The specified longitude, 8m. 7s., was deducted by scale measurement from an ordnaucc map, and the longitude in the proposed question was consequently expressed in hidcreal time.

Tho example which "F.R.A.S." has been good enough to give, should therefore be read thus :—Required the G. M. T. corresponding to 6h. Mm. 5039s. local S. T., on 15 April at n place whose longitude is

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Sideral interval since M. X. .. 4 41 3 whose corresponding equivalent in

Mean Time, is found to be .. 4 -10 lflQfi

Add long., expressed in M. T. 0 S 5 07

G. M. T. required 4 48 24(13

Now here "F.R.A.S." has adopted a method formerly practised by myself, but condemned aa erroneous by authorities no less eminent than Mr. Baxcndell, and the late Mr. Da wen. In No. 35 of the '* Astronomic^ 1 Register," Aug. lNitifVol. Hi., pp. 191. 208). are letters, from those geutlemen in reply to one from myselt sigued "Aicitincus ": aud in that from Mr. Dawes an example in given which is transposed, as follows, into the casein question.

h. m. B. Local S. T„ 1*;o, April 15 .. 6* 14 W30 Add long, west 0 8 7

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Sidereal interval since G. M. N. 4 49 11 :u
Sub. retardation of M.T. onS.T. u 0 47 37

Mean interval since G. M. N... 4 48 23-96

or, G. M. T. required It will be observed that the two answers to the question differ by 1*33., the connection npplied by "F.K.A.S. " (In accordance with what certainly seeii tobe the directioui of the "Nautical Almanac "i, to the S. T. at G. M. N, If tho 8m. 7s. finally added by "F.R.A S." wore allowed to stand for Sidereal time, tho same result would be obtained as is found by Mr. Dawes' method; but of course bidereal and menu time cannot be added together. Is the Nautical Almanac "Explanation" right or wrong: and is the G. M. T. at the time and place proposed. 4h. 48m. 22d3&. or 4h. 4Siu. 23DC*.? Not A F.R.A.S.

PARABOLISING SPECULA.

Sir,—I did not anticipate that the dilliculty expressed by "Novice " was of so simple a nature, or I would willingly have answered his question before; but now such answer is, I suppose superfluous, if Mr. Ulacklock's explanation1 met his difficulty. It is, of course, easy te Bee that if we have a spheric a-1 mirror whose central rays meet, say, in a focus of r-• inches, while its marginal rays meet in a focus of 61>i inches, it is just as practicable to make the centre oi the mirror more hollow, so as to give a focus,,'iu. shorter, as it would bo to flatten the margin, and so lengthen the outer rays to suit the central; it simply reverses the order of procedure, the only difference in result being that when the centre is depresBod, tinfocus of the mirror would be a trifle shorter than ii corrected by the other method. W. Purkihs.

REFRACTING TELESCOPE.

Sir,—It appears to me that It Is quite possible, from the data supplied by "Neptune," 2444, page 23, t<> give him a set of curves sufficiently accurate for practical purposes, though onr friend, *' A Fellow of the Royal Astronomical Society," does not seem to be oi that opinion. I do not find also, that "Neptune's"' flint disc is of " abnormally high dispersive power," an our friend imagines, but that it ts quite an ordinary piece of glass—at least as far as dispeision is concerned. Though "Neptune" does uot give the actual dispersive powers of his glass, all that Ts absolutely requiredt.c, their ratio, may be easily ascertained from hi? qnery. This is evidently 1 : 10, very uearly.

I have adopted Herschel's curves for glase of this description to the foci required by "Neptune," and I find the radii of the curves of hU crown lens must be lor the outer surface 137'501n., and for the inner 02'5Iln.t both faces of the lens to be convex ; of the flint, the Inner surface G0-2liu., concave, and the outer surface 280'87in., convex. These curves will give a correct result only for glass whose refractive indices are 1'5'Ji and 1*585, and will then produce foci such as " Neptune'' requires—viz., 6ft. lOin. for the crown, 10ft. llin. for tho flint, and 18ft. 3iu. for the focus of the telescope. Of course If the Indices of " Neptune's " glass are not as above, he will not get a perfect correction for colour. If he finds this to be the case, when his object-gla^s is in a sufficiently forward state to be tested, he can produce the required correction by altering the curveslightly. I thtuk he will find in practice that he need* oaly to alter either the outer surface of the crown or the tuner surface of the flint. He may by this una:-.. arrive at a perfect correction.

If " Neptune " is a practised workman, and perfectly sure of giving the curvative he intends, I shall.be happy to compute a set of exact curves for htm. In that case he must furnish me with the respective indices of his glasses, and their diameter. He had better also give me the radii of any tools he may purpose usiny. Henry T. Vivian.

POWERS OF SUBSTANCES TO RESIST THE PASSAGE OF THE ELECTRIC SPARK.— OPERA GLASS LENSES.

Sir,—I thank Mr. Russell for his letter relating to this question. What I wanted more particularly to direct attention to was the powers of substances to resist the passage of the spark. For instance, if the interior tubo of an induction coll be formed of guita percha, shellac, glass, or ebonite, what would be the relative thickness required in each case depending on the power to resist perforation. It Is evident that iu this case an air space would not offer so much resistance as the above-named substances. Perhaps

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«how» this to be apparently useless, as the extreme raya of the pencil evidently do not enter the eye at all. I »hould be glad to see this matter criticised, as many mattersof this kind are ventilated through your journal. Л В object glass, a b pupil,

с d : ab : : 2 : 1, available aperture = cd.

S. T. Prestos.

p S.—Talcing 'the extreme diameter of the pupil nt ^in., the above considerations show that for a power of two diameters any aperture of object glass above Aln. in of no advaHtage. Hence the uselessness of object classes of large diameter for opera glasses.

COTTON SPINNING. ,

Sir,—I am glad that my Ietteron p. 59 has succeeded in opening thl subject of cotton spinning, and if we ■can only enlist a few more correspondents, I have no doubt much Information may be obtained by an exchange of views through the Mechanic. 1 shall be glad if " R. W. K.(' r any one else will give their •opinion on the following point—vlz.^Suppose a drawing frame to have 4 lines of rollers, wkh a total draught of 7, what draught ought there to be between the 1st and 2nd. 2nd and 3rd, aud 3rd and 4th rollers?

"Mutual Improvement's" rule for ascertaining the draught of a carding engine is correct, though it iippears as If his cullenders " took up " took quickly

Factory La».

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OCCULTATION OF SATURN

Sir,—Possibly Rome of your readers who did not sit \jp on the morning of April 20, till 3 and 4 o'clock may like to know what was seen of the occultation of Saturn •with so unpretending an Instrument as a 3in. achromatic by Slater. The aiaappearance taking placeon the bright side of the moon, with light clouds about, the planet looked very dull, and I lost It btfore occultation was

FUSES FOU CONCUSSION SHELLS.

Sir,—1 beg tosend sketches of fuees for concussion shells, which I have invented.

The sketches above show the fuses as fixed in shells.

The number of holes for the escape of flame may be Increased either vertically or laterally.

J = Common fuze composition.

1С = „ quick match.

А В = Sections of plugs of lead or other metal.

In Fig. 1 the pings are retained in their places by a thin wire А В of fusible metal, which is destroyed when the gun in tired, and the plugs are set free to tumble ontwards wben the shell strikes the ground.

In Fig. 2 the plugs tumble inwards as soon as the plug of cardboard or papier mache О is removed. In order to effect the displacement of D. It Is filled with rifle powder P, and becomes blown out when the gun is tired.

These fnses are not similar to Freebum's, or any fuse that has been invented prior to 1863,

OiiivcK Ualdane Stores.

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BACK-WHEEL BICYCLE.

Sir,—It may be only practice. Mr. Preston (21ПЗ) wants to ride the" back-wheel " bicycle he has made. The pressure on the treadles being of a different nature to that of the ordinary machine, requires to be learnt afresh, even though he may ride them. He ought to have 6* cranks, though, for a 38* wheel (ordinary bicycles requiro 6£* for а Ж wheel); the wheels are only 6* apart, not a foot, and if he has got a roller', advise him to take It off. The swinging bars are pf such a length as to make the treadles about 1ft. (¡in. below the level oí the spring, when they are at their lowest point, this suite most persons, but as theyr.-.n easily be lengthened or shortened, It is best to adju>t them till you get the size you find in -t comfortable. The swing bars are made of the shape shown i u the sketch. Leg rests can be put on to the projection in front, these do not interfere with the working. Persevere with it, and you will soon "make it go "fast enough. On the 2nd of April, I travelled on mine from Hampstead to Hendou, 3 miles in 15 minute*, with great ease. I have reason to believe it to be the easiest working velocipede I huve yet heard of. Certainly the " lever" principle is the best driving action. S. James, Kentish Town-road.

DRAUGHT IN A CARDING ENGINE.

Sir,—"Mutual Improvement" asks if the rufe he gives, p. ill, for the draught in a cardtne engine "is strictly correct." If he means for the whole of the draught in the engine, I answer,No!

The rule is correct во far as itgoes, but It only gives the draught between the doffer and the feed rollers; to get at the whole draught we must take into account also, the draught between feed rollers and lap roller, and also between doffer and call enders. The draught of a carding engine, or any other machine, is simply the ratio between the surface speeds of the first, or taking-in roller, and the last, or dclivering-roHer. If the surface speed of first roller be always taken n* equal to 1, then the surface speed of last roller will be always = the ratio of their speeds, which ratio is the whole draught in the machine.

B. W-, Rochdale.

COMBINED FUNNEL AND MEASURE.

Sir,—Enclosed I send you a sketch of a fum.el and measure combined, which I made some time ago, and

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Mean heat")
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Sud. J

Referring to theletteroi " F.R.A.S." ou "personal" matters, on page No of the English Mechanic, 15th April, 1870, fie says " Veritas " has been " preaching" СгОШ that text " Venus on the Sun's Face," as given in Vol.X., No. 247. Well, I admit the softímpcnchment, -without, apparently, obtaining many converts, but to •change the metaphor, I considered the production of u " Ь .R.A.S." a fair subject of criticism, especially as the data ere so circumstantially given. "as 277: TM : : 7000*: 18271 miles," Ac. But lie adds, "None ol tlichc figures are precisely correct, because we have uever gone beyond one place of decimals."

I do not, nor never did, hold " F.R.A.S." to a " rigid accuracy in [figures;" but I do hold that the eccentricity of the orbit of the earth, as given by Sir J. Herschel at001679, as measured by unity, the meau distance ought to be a guide, to which, when unity Is added, equals 1-01679, tale is the ratio between the mean and aphelion distance, and also the mean distance divided by the perihelion distance. i "To have gone into all the details and refinements of calculation," and thereby deduced or obtained the wjriect mean diameter anri distance of the Sun, would have been considered ample satisfaction bv

Veritas.

MOISTENING LABELS.

Sir,—Some time ago l obeerved a query in our Mechanic in reference to moistening labels and postage stamps, without being subjected to the—not always either pleasant or safe—operation of passing them through the mouth. The best reply I can make, is to forward for your kind acceptance a neat litte apparatus, that most efficiently (I think)accompllshee tbe object in view, without the drawback ot clumsiness that attaches to so many of the contrivances extant — lately brought out by Mesera.

i Savage and Son, Brighton. If you think this ingenious and natty device worth an illustration in

, your columns—so devoted to original ideas—it is at your service. They are made in several sizes, to suit thevaik>u>

i forms of lnb»l in use. The one I send is, you will

I observe, nearly square, and intended chiefly for wetting

Îostage stamps; the modus operandi is as follows, 'our a little water upou the pud, so as thoroughly to saturate it; place the label with the adhesive ndfl upon the pad, then press down the lid with the fingers; the brass spiral spring inside the box—which rnnstitutes the chief merit of the Invention—will raise the cover again when relieved from pressure, when the label or stamp may be lemoved and applied In (Inordinary way. Edmund il. T. Ttdeman, Brightou.

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which answers the purpose first-rate for all kinds of liquors, aud which I think will be useful to many of your readers. I made tbem in different sizes, and got them stamped. Seacomhe.

CHEMICAL.

Sir,—Whilst reading an old book several years age. I met with the following, which I wish to lay before your chemical readers :—" Sow eome cress-seed In Hour of sulphur, watering it with distilled water, iu order to prevent the introduction of any foreigu element. The seeds germinate, and push forth into a centre, nourished alone by principles known by analysis. Cut the stem into several pieces, so that you may have sufficient quantity to operate upon, aud by burning it you may obtaiu some heaps of ashes. In analysing these ashes you will find acid of silica aud of atumiue, ot phosphate aud carbonate of lime, o! potassium and oxide of iron—as if the cress had wandered or come from the sea-shore. Now, thet-e substances exist neither in the sulphur which served as soil for the plant, nor in the water that was used , we can only explain their presence by supposing вот« element common to the bodies coataiued in the cresa. and in those which surrouuded it. Thus, the air, the distilled water, tbe Hour of sulphur, and the substances contained In the cress—that is, potassa, magnesiti.aud alumine—have one common principie. From this irrefragable experiment we deduce the Oïlrtemt of the absolute—-a substance common to all na tu us, modified by a simple force."

Tbe idea contained in the above, which is, as I understand it.that all bodies are formed of ртч»г1у the same substance, ouly modified variously by MMH force or agent, is certainly a grand one. But I wish to ask our chemical friends if the result of the experiment is actually as above stated, and it so, what te the modern explanation? A. J. Smart.

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THE SUPPOSED PLANET VÜLOAX. 8m,—The observations of the eon, made with the view to rediscover the above planet in transit, concluded on AprlJ 10. and the observers agree in stating that during the time they have watched the solar disc no planetary body has been visible. The spots (macuta) have continued to be exceedingly large and numerous, and have presented some very interesting appearances. The larger group, which appeared ou the E.N.E. edge, on the 4lk met., and to which I called the attention of your readers In my last letter, continued to be visible until the 16th. It was seen by many observers without telescopic aid, and I have numerous sketches of its appearance when examined with a high magnifying power. J enclose two, made by Mr J. W. Backhouse, of SuodeTland, with a 4Jtn. refracting telescope.' Mr. Backhouse also obtained some measures of the size of the penumbra, and fouud that on the 6th April, at 4h Sum., it was 83,008 miles lotig. and 64,000 miles wide. Its umbra: were, however, small in proportion, the largest being but 13,000 miles long. Ou the 8th, the penumbra was reduced to 67,000 miles iu length, and 48,000 milis In width. On the Hth, at 31». 20m., iu greatest length was 58.000 miles, and m greatest width 30,000 miles, on the 15lh, at îlh. 15m., the length of the penumbra was 60,000 miles. In addition to the immense cluster referred to above, numerous others were visible on vurlous parte of the disc, and the following are the numbers noticed by Mr. J. ti. K. Klger, on several days :—

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Mr. Elger, in referring to the large spot visible on the 7th, says, •* The most rapid changes were remarked in the long straggling umbrae of this spot. There were evident traces of cyclonic action going on, shown by the spiral streaks, and markings within the penumbra. 1 have been in the habit, during the last ten years, cf constantly observing large solsr spots, but I never witnessed such a changeable group before."

»r. V. R. Bin, F.R.A.S., In speaking of a small group visible on the 0th, says:-" April 7. This irruup has become enlarged still more, assuming the character of two other conspicuous clusters, one In the a. the other in the N. hemisphere, consisting of two spots, one preceding and the other following the central portion, or apparent focus of disturbance; a feature which 1 constantly noticed in my sun spot observations, nine or ten years ago. The gronp in question, of which I noticed the earliest formation, has now become extended by appendages of spots, N. of the two terminal ones."

Mr. Birt also says .—" Between March 29 and April 7. the spots, which have been very'numcrous, may be divided into two classes, large isolated spots, or pairs Ol euch spot«, attended with comparatively small penumbra, and preserving from day to day ihelr distingui.hing characteristics; also lar^e groups of insignificant proportions, containing numerous umbra?, and a large extent of penumbra, the disposition of which has altered from day to day.''

Throughout nearly the entire period selected for the observations, the weather was very tine, but definition was not good, and It wae frequently fouud impossible to obtain good views of the spots, when employing high magnifying powers. In a future series of observations, it L proposed to obtain tho co-opcratlon of observers at more distant stations. И . ;.млм V. Denning, Hou. Sec. Observing Astro, nomlcal Society, Ashley- road, Bristol, April 18.

THE "PHANTOM."-" OVEIl SIXTY." Sib,—Id further reference to the " Phantom" wheel, 1 have just had my attention called to an article under the beading " Wheel," in the "Penny Encyclopedia,' whereby it appears that so early as 1838, wheels for railwuy trucks were constructed upon the "suspensory " priuciple. and though immeusely Btrong, were not found eufnciently elastic to answer the purposes of good carriage wheels. I aleo remember, within the last twelvemonth, to have seen, either In the English Mechanic, or some other acleatlUc journal, a ootice

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of я wheel ol similar construction, in use (ae a gig wheel) by a geotleman in London; but Id thie case the spokes were formed of steel chains paseing over pulleys attached to the felloee or rim of the wheel ; thle would, I think, be 1еев objectionable than spokea of Bteel wire, as. although the so-called chain spokes might be a trifle heavier, they would not be so liable to fracture from an accidental blow, as the wire ones, and would, moreover, not prove so rigid and inelastic, thns two of the most serious objections would be overcome. I may observe, that the idea was suggested to my mind by seeing a boy's he-op, with a ring lied in the centre by piecee of etring lor epokee. The wheel and velocipede referred to in my previous letter will doubtless be remembered by many persons in the neighbourhood of Rochfort and Raylcigh, in Essex, in 1861-5; as will also a first experimental wheel constructed with a solid braes rim with very line wire spokes passing through in a precisely similar manner to the one illustrated by The " Phantom ' Company.

1 must also in all fairness add that I have never either triod or seen any of their wheels; but no one will rejoice more than myself, or be more ready to congratulate the "Phantom" Veloce Company if they have—Id anyway yet nnexplnined—succeeded iu surmounting the very obvious difficulties: in constructing a really strong, light, and useful wheel, on the " suspensory " principle.

In reply to " Over Sixty," page 115. I very much dislike anything having the appearance of "blowing my own trumpet," but as it is not a matter of trade to ine, and appears to be a matter of some importance to him, I can with confidence inform him that I know of nothing—and my experience is pretty extensivemore suitable for getting along iu a hilly country, or indeed any other, than the velocipede I fully illustrated and described under the ям de ylume of*" Leo," In Vol. IX., April or Mavlaet year of our Mechanic (3 of my vols, are now being bound, so I cannot refer), and of which the Editor said it was the only one he hnd eeon that really deserved a patent. But I preferred to make our readers a present of it.

Edmund M. T. Tvdeman.

NINETY MILES A DAY OX A BICYCLE.

Sir,—I have rested contented with reading only the opinions, suggestions, and experiences of your numerous correspondents on the construction, uee, and progress of the velocipede, and have been very much interested with the ingenuity exhibited by eome, surprised at the wonders told by others, and amused at the ridiculous nonsense of that class of your correspondents who ¡are eudeavouriug to ehow how to gain power and врееД by tho various magic contrivances of long levers, cranks, ,%c. It ie, however, useless dilating further on these absurdities. I saw an account in your valuable paper of April 9, I860, of some gentlemen going from Liverpool to London in four days. ThlB then appeared to me a great feat, and I considered the riders had done four days'hard work, as my notion of the velocipede has differed very much from many of my friends, lor I have always held that it is the rider who tnkes the machine with him, and not the machine the rider.

This opinion was very nicely explained by your correspondent " W." in your issue of Sept. 17, 1809, iu his letter headed "The Bicycle Tested and Condemned," which some of your subscribers would do well to study. I must eay, that although "W.'s" eentiments have exactly coucurred with mine till now, I begin to vary a little (though not materially) from him, since eeeing the account In last week'B paper, which I know Is true, being Intimately acquainted with the two perlormers, who were both at their post at the usual business hour the next morning.

Extract from Birmingham Oazetlf, April 10, 1870 :—

"On Monday last two young gentlemen, residents of Smethwick, performed a journey each on a bicycle from thie place to the town of Derby and back, being a distance of 90 miles, within the day, partaking at the last-named town on arrival of a substantial dinner provided by mine host at the well-known hoetelry, Shakspearc Inn, Bell-lane, returning the ваше evening on their vehicles in excellent order. We believe this is the longest Btretch performed within the time by any of our amateurs in the Midlands."

I would add that they were ordinary bicycles, with 36in. wheels and cln. cranks.

A liLiM I. Vit SUBSCRIBER.

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day among dyers, *c. Naturalists ascertained it to be the female of a berolpterous lneect. It wae found by the Spaniarde in 1518, on their flret eotry ioto Mexico, where it wae beiag used by the Datives to colour ornaments, &c. A-c, and is now extensively cidtivatrii there, in Tenerifle, nnd Algiere. A Spanieo priest introduced it into TeuerllTe in 1826. In 1840 M. Simounet, a Frenchman (evading the Spanish law, which threatened any one found exporting the insect from their dominions with death), introduced it into Algiers, thereby rendering a great eervice to bis country; for France was paying 9 or 10 millions of francs annually for the cochineals she used.

Fig. 1 represents the nopal plant, one of those peculiar succulent shrubs beloDglng to the natural order Cada, called by botanists Ooimrïa Coccinill\fera. "On this the impregnated females are placed. Young ones ore shortly developed, and about three or four months afterwards, when the females have become fecundated and enlarged, tho harvest commencée The Insects are remo»ed and killed, either by immersing in hot waiter or by the heat ol a stove." They are collected three times in the year, a few being preserved for breeding the (ollowing year.

The male only ie eupplied with winge; the female has none (Figs. 2 and 3;. and remains always attached

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to the leaf of the nopal. They ftre small, irregular, ovoid bodies, of a greyish red colour on the outside, and a bright purple red within. They are used chiefly for the ваке of the fine colour which they produce, and are principally consumed by the scarlet dyers. Alcohol, water, and solution of ammonia readily extract their colour.

Carmine is prepared from cochineal by decoction in water and the addition of a precipitant, such as bichloride of tin. What is thrown down, when collected and dried, constitutes carmine, six drms. of which is yielded by loz. of cochineal

H. E. Godfrey.

THE DETERMINATION OF THE PERCENTAGE OF SULPHUR IN IKONS.

Sib,—As this subject is of great importance to those connected with the metallurgy of lroo, I shall feel obliged if you will allow me space for a few worde on the procees deecribed under this headlcg by Mr. Hamilton in your paper of tho 8th lnet. The method of separating the sulphur from the Iron as sulphuretted hydrogen gas, which Is absorbed by the eolutlnu of potash, and the oxidation of the sulphide of potassium thus produced, by passing chlorine gas into the alkaline liquid, as suggested by Sir. Hamilton, is ingenious; but the process is objectionable for several reasons, which I think will prevent its coming into geperaluse. 1st. It requires great caro in the preparation of the apparatus, and strict attention during the evolution of the g»s. 2nd. The unpleasant odours,

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