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to admit it* being laid within the ehuttle. On pushing the point oí the reel to the holo in the iront end of tin- shuttle, the spring forces it in and retains it.

The Singer shuttle rcol is kept in place aleo by a similar bolt and spring, which is inserted in a hole in the front end of the shuttle, as represented at T, Fig. И; the reel R rotates on centre points. The thread passes from the reel to a slot S In the under side of the «huttle, then back over the reel tn the Up side, through -ou*1 or more holes, according to fine tension required.

The threading is arranged #n the same plan in the Thomas's shuttle, represented at Figs. l> and 10. but the reel is square ended, and rotated in a hole in the point end T, and & slot U i in; fne thick end of the «huttle, a latch V laabown ope», «ad le made to turn on its centre pin into its slot W. which tt fits tightly. To hold the reel in place in the »tee С я piece of watch spring X le soldered iueîde tira Shuttle to press the reel outward against the latch V. ïftls spring is an important part in the regulation) of the ehuttle tension.

The top holes in the shuttle admit of threading either through 1, 3, or 5 holes«, but not through 2, 4, or <i holes; this is a delect in shuttles of this class, but is compensated for in the Thomae'e shuttle by the spring X. Practice enables the operator to bend it to lires« on the reel and thread so as to give the required tension.

The Howe, Thomas's, and Singer class of shuttles differ in their length and thickness. For machines of corresponding power doing the same kinds of work, for bootmakers, tailors, Ac.,, the Howe ehuttle takes i'.in. of the needle thread to pass around it; the Thomas's from If to 1-ltfth, and the Singer 21n. The length of the Howe shuttle m !фп., Thomas's 1 7-8th inch, and Singerai? l-liith inch. The Howe shuttle will hold 17 yards of No. 24 cotton, Thomae'e 15 yards, and Singer's* У0 yards.

There is a defect in thick shuttle* like the Singer requiring 2in. of thread to pass around it, because this 2in. must pass and repass through the eye of the needle for each stitch made, so that for 1000 stitches per minute, the passing and repassing of the thread through the needle eye will amount to 4000ln. per minute, while the Howe or Thomas's requires only iiCOOin. per minute.

This one-third increased velocity over a thick shuttle, and through the needle eye, tends to fray or weaken the thread, so that the stitch cannot be drawn up so tightly, except by reducing the speed, or using a better and dearer quality of thread.

The thick shuttle ie much used for slop clothing, but where strength and beauty of stitch is important, the Howe is preferred for best work, the Thomas1 я for flowering toe caps of boots and for the beet description of tailors' work.

Thus the long thin shuttle has the preference; it holds Its placo for the best work, and has not been condemned, although much hae been said about the en m movement for driving it, but why it should be condemned it is hard to ma ko out, seeing It is exact in its movement, and allows for the working of the best ehuttle.

The advocates of the thick ehuttle drive it by a crank, or eccentric, which makes the shuttle travel a longer stroke t han is required, und times or adjusts it bndly for the needle thread. It not only has the long loop referred to passing around It, but it also places extra strain upon it. To sum up, it is the best contrivance for fraying, straining, an 1 spoiling thread.

It must be allowed that driving the ehuttle by a crank, or an eccentric, would be an improvement over the cam if it were equally efficient. The reduction of noise land wear would recommend it, although the difference, when the workmanship is good, is but a trille, a well fitted cam and roller lasting for years.

Some of the more recent machines, put forward as wonderful improvements, multiply the evils referred to by straining a long loop around the shuttls, and at the same time cause the needle to rise before the shuttle has passed through the needle loop, so that the thread is being scraped by the shuttle and the eye of the needle, in two places at the same time. What would a lady think of an inventor coming iu to improve her sewing if, while she was pulling her thread through, he used two instruments to scrape or fray it? Thus, at the samo time spoiling its appearance and making it weak. No lady would allow herself to be deceived in this simple way, but let the thing be done out of sight, in a fewieg machine made to please the eye, recommended by a skilful eperator, with a cunninguseof words, and then the inventorie so far successful as to sell a machine not constructed ou sound mechanical principles, which the purchaser will lind no to improve by use. but to cause much perplexity and trouble for years.

Agaj.net the use of a shuttle machine the following object ons arc urged by makers of the Spool lockstitch machine :— *' The shuttle stitch is used principally in large machines for heavy work. It requires both heavy and noisy machinery, as the shuttle used is aboutüin. in length, and weighs more than a quarter of an ounce. In forming ouo stitch it advances its entire length through the loops, and recedes the same distance, consequently moves four inches at each stitch. The movement being reciprocating, the shuttle must be started, moved forward, and stopped, started, moved back, and stopped again at each stitch ; that is, power must be applied to start the »huttle twice,stop it twice.landmove it four inches at each stitch, besides the power required to drive the needle arm and other movable parts of the machine : hence the necessity of cumbersome mechanism, which renders the machines heavy, noisy, and c^-irely unfit for the use of women and lor domestic purposes. In working thin material, as thL- tension of the two threads requires adjustment, it is difficult to bring the lock of them in the centre of the fabric; the working of the ehuttle produces the zigzag stitch.; the lines of thread lie too high above the surface of the fabric; the management of the shuttle-thread is difficult, particularly for fine work, and fine thread cannot be used successfully with it."

The first objection as to weight nnd motion applies equally to the feed movement of the Spool machine, and would appear mort- complicated if described. The м токе er travel of the feed being Ц of an inch, while : he shuttle stroke Is 4 inches, is not to be considered

an objection, being useful work performed, which ^ muet take power o» any plan, even if the thread be carried around the spool.

"The necessity of cumbersome mechanism, which rondure the machines Heaary, nofny, and entirely nnfit for the use of women aud fi>r domestic purposes " is я mistake; instead of weighing more than a quarter of an ounce, oue-elxfto of an ounce ie the weight of a shuttle in machines now working with great satisfaction and with greater power, at a less expenditure of force, being smaller and lighter, and with no more parts of cumbersome mechanism than a Spool mochine.

*' The tension of «he two threads requires adjustment," and the shuttle thread can be adjusted to any degree, but the Spool thread ie limited. The only objection to the shuttle is ite nofsc—click, click at each stitch ; it is;a merry sound and they are wise who use It; in a good machine it does the nuest and widest range of work, with the least trouble. In some machines the click, click, of the shuttle is reduced to a minimum by carrying it on its frame, instead of striking it forward and* backward to slide on its bed. A Practical Man.

THE TELESCOPK.—ÏT3 CONSTRUCTION AND COUNTING.

Sir.—I believe that I can give "tbe-IIarnionlmie Blacksmith " (p. 110), in a very few lines, everything that is at present in print with regard to the performance of Mr. Newall's gigantic refractor; as also with respect to that of Mr. Buckingham's. My extracts are taken from the " Report of the Council oí the Royal Astronomical ¡i Society," presented to the fiftieth annual meeting on the ilth of last February. The first has reference to-Phe great Cooke Telescope ; in speaking of which, after;describing its construction and mounting the Report goes on;to say: "Mr. Norman Lockycr, who had an opportunity of examining and trying this magnificent instrument shortly before fate despatch to Ha owner, 3Är. Newall, speaks in the highest terms of its mounting and mechanical arrangement« generally; and so far as he was able to judge of its optical performance, with the low power to which the state of the weather restricted him, he considered it to be very promising." My second extract is briefer still, and Is made irom the notice of Mr. Buckingham's instrument; "regarding its optical periormance, we have, as yet, no definite report."

That very unimaginative person, the Governor of Tilbury Fort, in Sheridan's play of •' The Critic." says (in his attempt to check his daughter Tilburina'e rhapsody), "the Spanish tleet thou canst not see— because—it is not yet in sight." For an analogous reason, I cannot proceed to quote any further from

Erioted accounts of the two big telescopes, simply ecause there ore no accounts printed to quote from. 1 regret that the information I am able to nflferd 1« so vague, but trust that our famous Musical Artificer will—like the Proctors In Doctore Commone—•' take the will forthe deed."

Touching the " H. B."s idea of platinising specula, I should not be hopeful that a mirror would emerge intact from the heating ordeal, at all. Mr. Purklss.ae a practical manipulator, would however be the man to test this.

I may inform Mr. Frank Fothcrglll p. 114, that the object glass to which he refers as having been commenced by me some time since, ie etill incomplete. I have worked at it in euch an extremely desultory fashion, that I do not look forward at all hopefully to finishing it. I do not, however, plead guilty to sheer laziness, nor wish Mr. F. to imagine that I should derive any gratification from the application of the words of Tacitus to myself: "Utque alios industria tía funic ignavia ad famarn protulerat."

Mr. FothergillVqueetlon as to the linear difference in thickness between a spherical, speculum and oue iu the form of a paraboloid, pertains to Analytical Geometry. Should your correspondent be familiar with the theory of axes of co-ordinates as applied to surfaces of the second degree, he can work the matter out for himself, but if not, It is absolutely impossible to explain it in intelligible language.

Rigel being now practically out of sight, I cannot comply with the request of "Stella " p. 115, to see with how small an aperture the comes can be observed. I may just, however, say that the late Rev. W. R. Dawes saw it, and made a diagram of it and its primary, with a telescope of 24in. focal length and

1 6in. aperture ; employing for the purpose a pancratio eyepiece and a power of 70.

I must congratulate "Neptune" on having secured the services! of such an obviously competent computer as Mr. Vivian (p. 135). Only I hope that, for the benefit of the whole optical world, "Neptune" will favour us with a detailed account of the performance of his telescope, should he construct it from the curvee which Mr. V. makes so little of calculating. By-the-bye, when,as a lad, I had some mixed mathematics drilled into me, 1 used, If I remember rightly, to be told that the rule for finding the principal focus of an. unequally convex lens was to divide twice the product of its radii by their sum, As I write, I juet try this on the edge of my paper with Mr. Vivian's first lens, and can not make

2 X 137*50 x 62-51 - come out S2In., or 6ft, loin., for the

200-01

life of me. I have not taken the trouble to pursue this very eccentric computation any farther, Ex pale HiTctilcm, and I can fancy where J should land, were I to go through it all. But that I consider Herschel's formula; to be open to tho objection that a slight error in the radii of the tools involves serious consequences in the ultimate performance of the object glasses ground on them, I should advise "Neptune" to buy " Herschel on the Telescope," a threeand-sixpenny book published by A. and C. Black, and (If he be enough of an algebraist tobe able to inter

SolateHo try whether he cannot do nearlylas well ae tr. V. in working out tho radii of his object glass himself.

With regard to what Mr. Preston states on p. 136, I would just observe that it is the size of the emergent pencil with which we are more immediately con

cerned in an opera glass, if the diameter of this pencil be greater than that of the pupil of the eye. there is so mueh light wasted, but as long as it Is smaller than that of tho pupil, the larger the object glass is, the more brilliant the image it transmit«.

1 do not understand Mr. 1**8 diagram, inasmuch as fio places the eye in it, about halfway between the leus and its focal point. In reality he would eeoexceedingly little with bis eye in such a position.

I suppose that the Rquatoreal mounting o£ "H. A. C.s" telescope (2618), p. 142, has been con] structed by the maker for the latitude of his ubsea vatory, so as to require a very trivial adja»tmeu^BI the polar axis to give it the proper elevaiiun '.' ТЪе flrct thing, then, that he will have to do, wili be to assure himself thai the polar and declination axes are at right angles. This he must do by means of a, spirit level on the pivots of the declination axis. Then he must get the optical axis of the telescope at right angles to the declination axis. He will effect this by inverting htatraueit eyepierp, retting the telescope in. advance ofa star, reading tho vernier of his hour circle, and then noting the instant of the star's transit over his middle wire. Now turning the whole affair ball round on the polar axi», let him again reclamp the telescope a little in front of the same star, again read. the vernier, and once move note the time of it« passage over the middle wire; then the difference between ehe Arnes of transit, and that between the two readings of the hour circle ¡«honld covurlde accurately. If not, he must correct the errer, if small, byshifting the wire frame through half the interval in the eyepiece; if glaringly large, by altering the position of the telesoope itself in the cradle. After ifil» he will have to see that the verniers of hi* declination circle read correctly. For tit la purpose let him thread a star on the declination wire, and read off its declination on the circle, then taming tbe whole instrument round on the polar axle, again thread the star on the wire; then half the difference of the circle readings will be its index error. Should this be large, the vernier must be adjusted ; but if not sufficiently so to interfere with fiuding a star, it had better be left alone. Finally, once more carefully levelling the declination axis, he must make the vernier of his hour circle read XII. or XXIV., л» the cose may be. These instrumental adjustments being complete inter ее, all he will have to do will be to set the declination circle to tbe declination of sumo known star (allowing for refraction, and, i/ needful, tbeinelex error of his circle), and then as tbe star oros*es tbe field, to elevate or depress the polar axis bodily by телпа of the proper screws until the star пша along the declination wire. Knowing his local ftbe he can now get the instrument into the Meridian in the way reFerVed to on p. 85, by one operation ; una should he succeed in this, and in the other adpieimenta to which 1 hnve referred, he ought to have no difficulty in finding suchas star us Castor, iu the middle of the day.

'--Scorpio " (ЭчЭД, p. ИЗ, may find the focn* of any Huyghenian' eyepivce, when he knows the foci ot it* connût tien« lbneee, by the following very simple formula. Divide twite the product of tbe focal lengths of the lenses which compose the ev¿piece by their sum, the result will bo its focus. Thus, if we have a field lens of yin focus, and an eye lens oil,

2 x 3 к 1

= lj, so that a Huyghenian eyepiece ю

4 constructed would be equal to a single lens of ijin. focus. The division of the fooal length of the objcti glass by that of the eyepiece gives the power of tí», latter. Secondly, 1 may inform my querist that li should not only think a ;>in tosiese ope "good" which would show tho 5th otar in the trapezium of 0 Orionis, but miraculous. .4?5In. 1 should put A3 the very smallest aperture witn which it conld possibly be picked up under tbe most favourable conceivable circumstances. An eye like that of the late Kev. W. K. Dawes, a Dallmeyer objpet glass, and a superb night being conjoined, this speck of light might be seen with tbe aperture I have assigned. Thirdly, will Scorpio refer nie to the volume and page in which I stated that a 2}ln. telescope would not divorce stars lex* than 2**5 apart? because I have tfo recollection whatever of ever having made any sue h assertion. I think it likely that a realty first el* s s Instrument of thta aperture Would /fjf split ai* pair of stars. The application of Balltheyer'e formula (which I have myself given long ago more than once ie your columns), is almost too crucial a test for any in* strument. Fourthly, the erdiuarylluyghenian eyepiece is used indifferently -nth reflectors;or refractors, ¡u is the Unrusden, or positive, eyepiece for micrometre work. Finally, I should think that tbe Star in the larger telescope spoken of by your correspondent. would look rather smaller with 700 than it would with-50 in the smaller one; but focal length would enter as an element into this, th« image belog a spurious one. C.clrrii paribus, the shorter the fucus of our object gl a*» the smaller the disc of a star. A Fellow or The ио^льЛатяонолггсль Society.

ASTHONOMICAL.

Sin,—Assuming that Mr. Fotliergill, p. 114, is correct about " IHei rich sen's Almuuao," tho computer of the Kphemerls therein contained, must have made some odd mistake. A planet such as Mercury or Venus may change its declination perceptibly between its time of rising and setting, so that the interval between its rising and culmiuation may differ from that between its passage over the Méridien and Its setting: but in tbe caso of л fixed stat—and Л1г. K. speaks of" a Star "—its declination practically dbes not vary at all. So that its diurnal path is accurately bisected by the Meridian.

I cannot give "Scire Volo" (2Ä21). p. 118, the longitude of Belfast with extreme accuracy, but he may take its time as being fini. .'189. of Sidereal time, or lîin. 37s.of Mean Solar time slower than tnatof Glasgow, with aprobable error of not more than a second.

The query of" A.U.Z." (-558) щ almost meanlugleas without some ludicatiou of his locality. In London just now the Magnetic Needle points V,P 5ir to the West of North, but this declination varied шлг1ык11у oven in different parts of the United Kingdom. To take the »lace, for example, I havejust mentioned in my previous reply, Glasgow, the declination this year mUi ,6,. whlleit Dover it is only 10° 10'. This will serve to show how very vague any answer must of necessity bo to your correspondent's question in its

Wl'tn'ragara to the letter of " Not a F.R.A.S.," on p. 135 I must eaudldly confess that I have actually been foolish enough to apply the correction ficin- ow: teiortae in a very careless wny, that the difference in longitude already included it. His secondexainple i* rijbt; and mine on p. SO. only correct for the purDosc of obtaining his local mean time. Obviously, whatever th« Sidereal time tie at his supposed station, u is at that instant 8m. 7s. mere at Greenwich i and as it is Greenwich Mean time we are seeking, we must take the Sldrreal time at the preceding Orremneh mean noon from L.S.T. + 8m. 7s. (and reduce the result to mean time) to get what we require

There would appear to be a recent fashion, with people who havo nothing else to give, to offer prizes. May I commend this to the attention of " V oritus. p. 106 and counsel him to «iffcr sn organ, telescope, nsh keltic, "History of England," set of flat irons (or something equally appropriate) to any one of the readers of the Eniilibb Mfciianic,who will explain the penultimate and concluding paragraphs in his letteron the page referred to? _.,,„ _

Ceteris pariiwT, I may tell Mr. D. E. Williams, (26061 p 142, that places on and near the Equator nave the shortest dawn and twilight; and those near the Poles the longest. This arises from the fact that it is not absolutely daik until the Sun has descended 18° below the horizon; and that in latitudes where he is over head, he of course rises and sets perpendicularly; and very rapidly describes this arc of 18°. On the other hand, in high latitudes^!* path becomes more and more ohlique to the horizon as we approach the Poles, and he is a long time before he attains a depth of IS" below it: the ultimate result being that, even in England, at one season of the year, he never descends so deeply as this, and consequently there is no real night; and that as we come still nearer the poles, we arrive at a parallel of latitude on and beyond which. fur half the year, the Sun docs not set at all. If Mr. Williams has access to au ordinary terrestrial Globe, and will merely stick a white disc of paper on any part of the Ecliptic he pleases, and elevate the Pole of the Globe to various heights, he will be able to see the reason of all this at a glance. To imitate the condition ofthings on the Equator.allhewill havetodo, will be to place the axis of the Globe parallel with the wooden horizon, then turning the Globo on such axis, he will see his piece of paper rise and set perpendicularly. If now he will elevate the axis until it is perpendicular to the horizon, he will observe that his white paper sun will travel round and ronud paralle. to it: of course at intermediate inclinations, describing paths of greater or less obliquity. We may And out, to select a famllar example, the time during which twilight lasts in Loudon all night long, by considering that the Latitude of that City is 51" 30', or in other words that the Pole is elevated at that angle to the horizon: then, adding 18° to this we get 69° 30'. But from May 23rd until July 20th, the Suu's North Polar Distance is always less than this. So even at midnight, when he is due North, he is less than 18° below the horizon, and consequently there can be no real night. Any common work on Astronomy will give Mr. Williams further details ou this subject. A Fellow Of The Kotal Astronomical Society.

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Ilence — as in the lstoiuatlon, and then y, aud.changIng sigus, .c,again! roots, total 10.—Behnardin.

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EAKTH'S ROTATION.

Sir,—"C. B. O., Hants," adopts a mode of discussing centrlf ngal at tendencies which is a favourite ene of my own in all snch matters. It is so simple and clear as to be worth notin . In all such questions, one has only to consider w jat is the change of direction effected in a given time on a body moving with a known velocity to estimate what force has been called into action. By this aimple principle I was able in my " Saturn " to weigh Saturn agaiust the earth (by considering motion of his satellite Titan) without even having occasion for an illustrative diagram. The principle is very fertile.

I present my compliments to "C. R. O., Hants," on the lucidity of his reasoning.

Richd. A. Proctor.

FIGURE OF THE EARTH. Sir,—Mr. Benrdsley Is an ant pupil of " Parallax," and will soon quote others to his purpose as cleverly as his teacher. He quotes me as saying the earth s rotation can be proved by the simple fact that a rotating scmicirclemay be made to keep pace with the sun. / said nothing of the sort. He quotes me as making a certain remark about Tyctao Brahe's system. / made w such remark. Paradoxists may be divided into two great classe1. 1 know now to which Mr. B- belongs. What I really said of the experiment referred to was that it proved that if the sun move, his motion is of a certain character; what I said about Tycho Brahe referred, as B. knows, to the subject of the earth's revolution, not to her rotation.

"W. H. L." wants me to argue with Beardsley. With thanks, I decline.

Mr. Dyer must be n very young man not to know that Parallax and Co., are merely types of a Cubs which will always exist. Suppose "Parallax" do*s "unsettle the minds of mauy people who have not studied the subject." What then 1 It serves them right for leaving the subject unstudied. They have been settled in ignorance, and " Parallax " is unconsciously doing capital work by unsettling them. More power to him 1 Richd. A. Proctor.

P.S.—In the hope of encouraging Beardsley to grow into another " Parallax," I invite him to screw up bis courage, and invent a reason why the sun, supposing it to set, as shown in his Fig. 3, (borrowed from " Parallax)," does not seem to vary In size, with those awkwardly varying distances. He might extend his proof to the general solar motious as conceived by hiM teacher.

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DLUE MAHOE WOOD FOR FISHING RODS.

Sir,—Our friend " The Harmonious Blacksmith," p. Ill, last number but one, wishes some information about blue mahoc wood, which ho aays is excellent lor making Ashing rods. He asks also where he could purchase It. I made some Inquiries about the origin of that wood, and hope the following particulars may enable him to obtain it.

The name ef mahoe or mahot is given to several plants, especially to different libre-yialding I/ibiaeun. also to some Ltarthu and Vombeya. Mountain Mahoe (Hihuaia elatus) Is soft, high: a shlniile of that wood coming from Jamaica, was exhibited in London, 18(12, and said to last 6 years without any pnlut. Seaside Mahoe Is UiOUcm tiliactiu, of which there is a white and also a blue variety; it Is, I believe, 0ft. to Sft. high; its name in Panama is Mayagua de la playa. Now, I find in a catalogue of MM. Fauntleroy and Co., (actual firm. Mundy, Horley and Co., 100, Bunhillrow, E.O.) the " Mayagua azul wcod." and this will be. I believe, the "blue mahee"; having no sample I cannot further examine it, but it wifl be easy for "the H. B." to apply to that firm, and I shall be huppy If I have obliged him who has obliged so many brothcr readers. Behnardin.

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AN ENGLISH MECHANIC MUTUAL IMPROVEMENT SOCIETY FOR BLACKBURN.

Sir,—As I feel certain there must be many subscribers to yonr excellent journal in Blackburn, I beg to suggest that a few of them who know each other should meet together, and arrange to have a meeting such as our Edinburgh and Manchester brethren have resolved upon. No doubt we could muster a goodly number, and help on this new intellectual project; for encouraging the arts and scieuces. J. Harrison Moran,2, Brook-st., Eanam, Blackburn.

SALADS.

Sir,—Pormlt me to draw attention to the value ot dandelion leaves as a salad. Although much used abroad, the plant is little appreciated here, as Indeed many others that might enter into our dietaries. At this season of the year, salads constitute valuable articles of diet. They are recommended not only on account of their cooling and refreshing taste, but chiefly from their containing mineral matters, which are so essential to the maintenance of health. These mineral matters consist principally of suits of potassium and sodium. When vegetables are boiled, a certain portion of their mineral constituents is extracted by the water, and hence the practice of eating uncooked vegetables and fruit is a most wholesome oue, as furnishing the system with saline matters, which are much needed. The following plants are used as salads in this country :—beer, celery, endive, garden cress, lettuce, radish, and water cress. To this list might be judiciously added the leaves of the dandelion. Lamb's lettuce, or icorn-salad, sorrel, aud many other wild plants, which through ignorance or prejudice are at present despised.

In making salads it will be found an improvement to use the leaves tolerably dry, to add a fair quantity of good oil, and not drench with vinegar, as is too often done. Beta.

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CASE HARDENING. In reply to " St. George," I inform him that it

is not a new plan of case hardening, although it was not generally known. I have used it for years, with only this difference, that I put about one-third of suit among tho prussiate of potash, either in a retort or ou the red-hot iron nt tho smith's fire, and by re-heatins; and giving it another dose it will be better. .1 casehardened some things about two years ago for experiment, and dipped them iu a mixture of one-thiril ot sulphuric acid among tho water with good results. Everyone was surprised that saw them, and so was Heathen Jack.

SCREW CHUCK.

Sir,—I have been looking for a reply from "Marine," In answer to "J. K. P.," who says he is in error in saying that "A. B." put a left-handed screw ou his chuck. He says: "I know a machine with a screw on each end, the one right, the other left. II "J. K. P." saw a machine any other way it wns wrong; for if the baok centre is screwed in the spindle, it must be a left-hand thread. In the same number (202) "J. K. P." gives a drawing ot Bennetts chuck. The thread is put on right-handed, and it is the reverse of that of "A. B." If "Marine" was in error, how are they not both the same 1

Heathen Jack.

INDIA.

Sir,—Probably there are very few places on the earth's surface where ancient civilisation and barbarism have co-existed Bide by side, as it were, to an extent equal to wbich has prevailed in wha: now constitutes the British dominion in India. At a remote period our Arynn ancestors conquered this country, but of course their conquest was not a perfect one fno conquests ever are, excepting those domestic conquests achieved by wives over husbands?, end the Aryan. conquerors became to a considerable extent amalgamated with the more ancient populations, which was probably the origin of the complex system of castes which grew up, the pure races, as the Brahmins and i he warrior caste, remaining the governing classes, as", indeed, soldiers and priests, when united, almost iuvariably do, "even until thiH day."

In India the conquering гас«, to a considerable extent, adopted the superstitious of tliosethey subd led. Modern Hinduism Is anything but the pure theism of the an« eíeñt Aryans, as (taboo KeshubChunderSen would tell us; and some of those ancient populations seem not much, if any, further advanced in civilisation now than they were thousand** of years ngo, when the lightercoloured Aryans conquered them. Nevertheless, they have in many instances re-occupied their lost ground, from which the higher race has retired, although they do not seera to have " improved tbe occasion," and copied the example of those who temporarily occupied, слу, the site of the city of Mitndoo, whose architectural works would do honour to Greek and Koman civilisation, if, indeed, their remains do not surpass any ol the works of those peoples, except in statuary. J he grouud on which the remains of this ancient city stand is now occupied by the savage tribe of liheeb, who are not only incapable of mason1* work, but are roo barbarous to build even a comfortable hut to shelter them, or to cultivate the earth for their subsistence, and, like the Santhals, they are yet only armed with bows and arrows, a most convincing proof of a low мл te, for there can be no doubt whatever that gunpowder and the gallows are tbe most salient signs of civilisation. The Harmonious Blacksmith.

lng ''Joe" and others against being taken In by any of that old nonsense about rods weighing an ounce, or less, per font of their length? He has seen a roach rod 22ft. long, weighing only 21oz., and its action was very good without its butt. This remarkably small weight was obtained by boriug out Its butt—made of shaved jungle bambeo cane—until It was less than ¿in. thick. Need he add that it was soon split to pieces. When a suitable butt-joint—made of East India bamboo—was substituted lor it, the rod became faultless; but then it weighed a few ounces more. No doubt it weighed heavier in Ш bag, but it did not/er/ heavier in the hand when In nse, for the very simple reason that the additional weight was at that end nearest the augler. A very alight weight added to its top would have been much more felt, just as a small lieh feels heav) to lift out of the water with a long rod.

SHEATHING IRON SHIPS WITH WOOD AND COPPER.

Sir,—t did not intend to assert that the Admiralty had definitely adopted a modification of the plan for doiug this which I designed about 1861, but ouly that they had adopt-d It experimentally—in the fast frigate Inconstant, if I am not mistaken. " In my design there was no difficulty in obtaining a perfect adherence of the wood, for it was confined in dovetailed iron grooves formed by affixing angle Iron to the ship's outer skin, and driving the wood into the grooves so formed. If I remember correctly, asphalted felt was introduced between the iron skiu of the ship and the wooden sheathing, so as to form a water-tight joint, aud prevent the injurious action of sea water ou iron in contact with wood. I am almost certain I have the coloured drawings of this design by me, and if you think, Mr. Editor, the matter of sufficient importance for a small engraved illustration, I will look them up aud send thern to you. In regard to its Importance I may remark that could miDe or some similar plan be carried out without too great expenae, iron ships might not only be employed as cruisers ом stations where there is no dock accommodation for large war ships, but in such services as the Southern whale lUliery, in which ;i ship often remains undocked for three successive years, aid unless sheathed with copper would become the local habitation of the great Barnacle family to an extent undreamed of eveu by Charles Dickeus himself.

The Harmonious Blacksmith.

A SOFT-VOICED PIPE FOR A CHAMBER

ORGAN—FOG-HORNS.

Sir,—At the southern extremity of the Isle of Wight au experimental fog-horn haw been erected, which is voiced exactly by the same means that are employed to voice the reed pipe of an organ; but those means are on rather a larger scale. The steel reed of this trumpet pipe is five inches long by two inches wide, and is put in motion by air at tbe pressure «f about lulb. to the superficial inch. How many laches of water this Is equivalent to I leave " Adept " and Mr. Kemble to " kalkalate." This wee pipe, or ehaunter, ач a canuie ¡?cot would term it, cau hardly discourse »No«r music, but its sound. A, second space iu the treble, must, I think, be sufficiently " strident" to satisfy «ven Princess Alexandra of the English Mechanic herself; for I am told it can be heard many miles out «t sou. when other sounds are so difficult to transmit through fogs.

A lifeboat is a very good thing, and I trust we English Mechanics will, ere long, add at least one more to the number of those which are stationed on our rockbound coast. But however desirable it is to save the lives of shipwrecked meu, it Is yet more desirable to prevent shipwreck; so I do hope thie nom may long remain exalted, and, as Sim Slick would have said its sound continue to be a caution to Tiiariners, warring poor Jack of the dangers of too near an approach to land in foggy weather.

Tue Harmonious Blacksmith.

BLUE MAHOE WOOD.

Sir,—" The Harmonious Blacksmith** respectfully informs" Joe "that he, the said Vulcanite, is not in the

market for fly rods, nor indeed anything else at prepresent, excepting- it be ancient and rare musical instruments, and that he has no intention of entering the market, for fear ho should himself be "sold.'

Banter apart, he cannot inform "Joe" the weight of his long three-joint North Carolina cane fly-rod, simply because It is not now In his possession, and can only say, iu general terras, that it was extremely light, and did not fatigue the user much more than a rather

Eowerful 12ft. hickory rod would do, aud that he nows no solid wood which would not be very much ueavier than bamboo.

THE FUEL OF THE SUN.

Sin,—Under this title a fellow blacksmith, who has rather more science than the ignoramus who writes this, bas produced an interesting work based on the hypothesis that all interplanetary and stellar space is occupied with matter identical with that found on earth, and that the sun, in his journey through space, is continually attractioglt to himself, at a rate probably exceeding 104) millions of millions of tous per t>econd of time, and leaving behind him a proportionate quantity of what tbe author, borrowing an Idea from his smithy experiences, terms exhausted fuel. This hypothesis appears to have the advantage of accounting for observed facts without requiring us to admit the existence of any unknown causes or new forces, excepting the assumption that the matter diffused through space is identical with that with which we are familiar, which seems at least very probable, although of course we must not assume that we are acquainted with all kindsof matter which i>ay exist in the stars, the sun. In other planets, or eveu our own, seeing that we are not acquainted with its Interior.

Mr. Williams thinks the temperatjre at the lower strata of the sun's atmosphere is rendered so high— probably far higher than the melting point of platinum—by that condensation which results from the great pressure due to the attraction of so large a mass; that the elements of|water, and probably all terrestrial compounds, become dissociated, and that those elements from time to time rise into the higher regions of the sun's atmosphere, again to combine, with explosions compared with which our gunpowder and iiltro-glyoerlue go off mildly. It is this re-comblnstion of tbe constituents of water, accompanied by that evolution of light and heat which we term combustion, from which be thinks most of the sun's heat and light which we experience is derived, and I do hope " F.R.A.S.," Mr. Proctor, "Sigma," and other

ÍHiysicIcns, who, of course, know all about the suu's uel, and everything else, will favour the unlearned blacksmith with their opinions ou Mr. Williams's theory.

Mr. Williams is of opinion that the solid, or more probably fluid, nucleus of the sun is comparatively a smalt body, whose position, in relation to the common centre of gravity of the solar system, is to a great extent influenced by the planets, and that to its somewhat irregular fluctuations within its atmosphere may be due some of those more violent explosions which lie thinks project matter far above its visible limit. Tо such projected matter he rrfers the cause of the zodiacal light, aud probably also the asteroids. He sees no specific difference between large and small partirles, and thinks that meteorolitesand asteroids are simply larger and smaller specimens of the suu's projectiles, differing from each otber only as small shot differs from cannon balls. If this hypothesis be reasonable, lean see no objection to its extension to the formation of all the smaller planets, say to Mars. For anything I can see to the contrary, the earth and all the rest, as far as Mars, differ from asteroids ouly in size, and may have been thrown off from our common parent, the sun, during one or more of his explosions—I hope not **f ill-temper, although be is said to be rather hot. Chemically, meteorolites and our planet resemble Caejaraud Pompey in being "berry much alike," and perhaps the latter are ouly the big \ brothers ot the former, for difference of size no more includes difference of genus that the huge magnitude uf ths elephant and the minuteness of a sucking pig prevent both from being pachyderms.

Perhaps Mr. Williams—in deference to the feelings of his weaker scientific brethren—feels the necessity of " drawing the line " somewhere, so, for thejprcsent, he draws it at Asteroids; why he should not include the smaller planets and our satellite, I can't guess. In a recent number of the English Mechanic, it is reported that Venus has lately had a baby (query, iVas its cradle the observer's telescope?;—I meau a satellite —now if the tun has been for ages projecting meteorolites and asteroids, until the interplanetary spaces arc thronged with them, it seems no more than reasonable that Venus may have picked up one, aud, like a charitable female, adopted it. Considering the grest distance her husband Mar» has been from her during л11 historic times, this seems и more charitable hypothesis than that her satellite is her own production, and as charity i< said to cover a multitude of sins, I hope mv charitable suggestion may cover some «f these manifold sins which, according to Mr. Herman Sloman, I have committed in the pages of our journal.

If the earth has picked up her moon in times past, and Venus lately adopted a little waif, which was sadly wanting maternal care, may not all the planets within the orbit of Jupiter have done the same, and really have attendant trains of satellites from the size of the smallest meteorohte to that of a small moon, of whose existence we are ignorant, ouly because they are too small to reflect enough of the sun's light to make them visible Iu our best telescopes? And may not some of them occasionally become luminous wbeu they enter our atmosphere? I *ve no very great difficulty In supposing the possibility of this, but that may be due to my crass ignorance.

As Mr. Williams think* Jupiter is a sort of miniature «nn. which our sun h;is picked up In his journey through space, "lu tbe days when he went gipsying a

down to the tempernture of a member Of the " temperance association of planets," if such a oody be. X have not included either him nr his four moons among those 6odies which I suggested may have been projected from oar sun In the olden time. If, as be supposes, the surface of Jupiter is now as hot as melted fdatlnum, and will never become cooler, I cannot iclp thinking t^it this great bomb, compared to which the asteroids are as sparrow shot, and the projectiles discharged from Mallet's mortar, mere grain« of sand, must have been in estate of mere gas when proyecte*!, if it ever were projected, from the sun, and ga*, Р^Тл haps rarer than hydrogen, could hardly have together, and however much condensed during* its jectory, been shot so far as J о pi ter is from tbe Mr. Williams also thinks that Jupiter, Saturn, TJ— and Neptune, and the planets, if any. yet mo tant, have photospheres, and that none of the originally had atmospheres, but have "pfeke^^ up" by attracting aqueous vapour, &c, fnufe^hDltevy. planetary space, just as I have supposed tbsnrplek. up their attendant satellites. That their atrial liquid surroundings, whether In the form of atme pberes or oceans, have been derived from without from within, is certainly a very interesting »peculation, but one, I fear, oflwhich there is what tbe Hibernian philosopher termed a very abundant lacle of data from which to estimate the probabilities of either hypothesis.

The Harmohiols Blacksmith.

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THE BOOMERANG.

Sir,—I herewith beg to enclose a sketch of a ematf boomerang, which I made myself niter an original model. I can throw it perfectly, and do so in tte» following manner—viz., I catch a firm grip of tbe loe; side near the -mint with the two forefingers tod thumb of the right hand, holding the inside Ы** direct towards the ground. I aim at an imaginar? object about 30 yards off, fetching the boomerang over tbe shoulder and flinging with a straight, smart throw, as if I wished to stick the point in the ground at tbe 30 yards' distance. It goes to the object straight, then gradually rising to a height of from Я0 to 100ft., sweeps away to the left, and comes down in a

[graphic]

circle and alights within a few yards ol where I throw it from, geuerally behind my back. I find it doe* its work belter when thrown against the wind, which should never be more than a breath. Mine is made of apple tree, but I fancy any tough hard wood would do, provided the grain run* parallel with the bead. Tbi* is necessary, for if the grain of the wood ran« across, or through the bend, the boomerang snipe in that spot when it hits a »tone or other hard object. I have made three or four now without auy difficult? except that of getting the grain right. They hare all broken at the bend owing to the straight gram. One I have used for two summers, сады ts grief last week. Anyone wanting further information will have it. and welcome, by applying through our unique journal It is ¿in. thick, tapered ou all sides to\ fine but thick edge. Vivís SP*Rakdcx.

HYPOCHLORIC ACID, &c.

Sir,—I see week after week thatyour paper is filled with valuable matter, therefore, absurd arguments are best omitted As to my communication respecting h у рос Ы ori с acid, I shall not argue—the acid da* not exist, although caustic alkalies absorb chloru» tetroxide. This latter was termed by Liebeg, in bit "Elements," chlorous acid.

My tardiness In replylug to " U," in your impression of the Stb, has been caused by my undertaking * series of experiments to determine bow far 1 resfif could go in separating barium chlorate from ib* chloride, and the result was that when operatimr with quantities calculated to produce 30/4 grms. of the chlorate I was able to separate 20 7 grms. of this salt. I shall no: give the full particulars unies* specially required to do so, as it would be only taxing up the space of your valuable journal.

If querists would only be more exact in stating what they require, and In many cases the purpose for which the article is required, they might citen be answered in a very few words. Kor Instance, in tb»? barium chlorate question, if the pure article was wanted, why not have said so 7 However, I bave, iu spite of our old corresponden* under a new fact-, quite satisfied myself that the pure article maybe obtained by my method, and in spite of the bold assertion made by the correspondent alluded to. the alkaline chlorates are, ca#Uy нерп rated from the chloride.

If such separations as these were the only operations of a laboratory, practical chemistry must indeed be an easy solence; but good instances of separations arc not to be found in «-uch single instances as the one Just illustrated, the difficulty increases almost to perplexity when we have to separate bodies of complex structure formed by the obscure action of reagents upon bodies ol organic origin.

G?or<ib K. Davis, Errata in article on ,; Symbols," col. 3, p. 98, for

«*,\ 'read £**! O,. Col. 1, p. t*9 three errors occur

in tbe formula; for tetrethyl ammonium hydrate, platosammonlum chloride aud ethyl aldehyde.

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BRKfflNO. ig »een from time to time тану loir pa"es relative to brewing without reply, f яш induced to seud you (another , lesertion, if you think desirable, the fol

\ystcry i« made about the art of brewing—it (easily understood—any one who can make bake ale or beer, the process boina; exactly (Puta handful of ground mnlt into л teapot. Vater nearly boiling, mix, let stand for some iroff the llqnor, add a few hops, and boil till breaks—that is. come» up in large flakes— law off to cool; when it has cooled toi about 70» add yeast to ferment it, and the beer Is The above is the whole art of beer rouklng, 04 a large or email »cale, and as many of your ■» may like to try their hand at it, I will proceed ¿TStaJIs. Kirst. utensils: these iu a unall way afesmid consist of n copper to hold, say 10 gals, a tub, ¿¡¿ear a sieve, funnel and tap, a tub for cooling, and 2 -> ли. casks. Take 1 bushel of malt ground tine, place in the mash tub, then add 2 gals, of water at d82° of the thermometer (not haying one, if it is sufficiently bot to bite the finger it will do), mix op well with, the oar so that it mav be well wetled-if the water Is too hot'It will set the'malt and prevent it breaking-after ■well mushing cover over with a sack, so as to hold the bent When this, the wort, has stood ono hour and a luir' try your liquor ¡ if it run» clear it is ready for boiline, If not ciaar put back again, and let it remain till clear, then draw off into your cooling tub preparatory to boiling. In thcmeanwhlle have ready a second 10 gal», of waterready to pour into the mash tub upon the drained malt at a temperature of WOP, ■well mash and let stand one hour, then draw off it clear and proceed to the boiling. You take the first ■«ort already drawn off. place it in the copper adding lib of hop» and a »mall quantity of salt, make boil, and considerable attention should be paid that only a ч en tie ebullition be kept up; after boiling about an bourand a half, flakes will begin tocóme up, and «hen they come up somewhat large will be time to draw off to cool, and here it is that written Instruction« fall—«pcrienMo dotes. If not boiled enough the beer la apt to taste raw aud sickly, if too much it will thicken, aud never be agreeable to the palate ¡ when boiled enough, strain through the sieve Into the cooler to cool toabout nV. Then take the second mashing aud boil in a like manner, adding lib. fresh hops— the old one* will not do-for, say one hour, then draw off to cool and you can add the two worts together. if so inclined, when at the same temperature—don t add the hot to the cold—to ferment together or separately, iu either case you add one pint new yeaet to each У gals of liquor, stirred well In, set aside to work for two days, thi» is best done by—haying Disced the beer iu bariele—filling up the barrels as they work over with beer retained for that purposein a week or so it will be resdy for use.

The above isbrewlng pure and simple, and I trust It will be found useful. Many an artisan could at all tiroes ensure himself a glass of good wholesome beer at one-half the cost he pays for the vile trash now purchased atthe public-the trouble I» not much when once the mill Is set a going If he will only have a little Patience ало Pebseverance.

METRONOME.

Sm,—I here furnish, in answer to qnery 2408, a ketch of this instrument unencumbered with the framework, In order to more clearly show its essen tlalprrts. IÏ is the mainspring barrel, its wheel of 120 gearing into a pinion P of lu. Upon nie axis of this latter, nearest the barrel, Is n wheel >V of 24, the teeth of which are of peculiar shupe, so ne, through an intervening contrivance, to give vibrating movement to the rod R. To explain this, I have made the sépanle sketch of this part enlarged. The object Involved i- that of converting the continuous motion of tbe wheel in one direction into that of an alternate Tibrating one at right angle toit; and If the action nos not already figured in the excellent plates of "Mechanical Movements," it is well worthyof description in the ЕяыЛвн Mechanic. The wheel teeth are very slightly undercut, and aro square, but with their acting front so bevelled as to be wrdge-shaped, their middle pins standing prominent. They are at Intervals of about two teeth from each other. Upon an arbor placed transversely to the wheel are Axed two snail-soaped discs D D, at such distance apart as to just have shake between any two teeth of the wheel, which in turning may embrace them, and also to allow of similar shake wheu either of the teeth is between them. The disc« are of equal size, but reversed in position, во that their acting slopes S, which are bevelled from behind, may stand in a line with each other.

Suppose now the mainspring is wound up, the front of a tooth of tbe Impulse wheel will press sgulust the aioptng edge of the back disc and move it aside, to the right, until the tooth escapes from it and drops on to the slope of the front disc, which it also drives aside, butin tbe contrary direction, until the tooth finally «scapes. A like action i» caused by the succeeding teeth, the rate of their escape being governed by the position of a fltttish weight or slider A, held friction tight on the rod by a spring clip, as shown In .the iiirare; for the rod 1» fix.-d on the same axis as tlie discs, moves with them to either hand/and, in fact, is л pendulum, whose rate of vibration is controlled by »hlfting iu centre of oscillation by means of the slider on the upward continuation of the rod. To dilate further upon this would require more space than the present communication warrants; suffice it to say that the frequency of the vibrations and their accompanying audible líente (the latter caused by the drop of teeth on the dead part of the discs, but intensified bv the resonance of the wooden case) can thus be varied lrom 40 to 208 per minute. The much heavier lower weight F Is to balance the slider, and by its momentum tho discs are carried further than necessary for , Ibe mere escape of the wheel, so that the lntter does not at onoe drop from the slope of ono disc on to that Of tho other.

■ The part remaining to be described is that for ■stTlkln» the recurrence of stronger accents on a bell.

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wheel, having only 21 teeth, will Just make 3 revolutions. The cum of 12 being on the same axis will, of course, turn at tbe same rate; aud if its teeth be allowed to lift the hammer tail Bhown at H, 36 blows will bo struck on the bell for every 144 swinge of the rod. This proportion of one chime to every 4 beats or swings will remain constant for any number the slider mav be placed at; but the hammer is mounted on a slide, and can bo brought into nction with either of the other cams, when the proportion will be different, and every second, third, or sixth beat may be chimed; or the hammer may be slid out of action altogether, the slide on which it is fixed terminating in u push piece outside tho wooden caí-e.

The instrument is easily stopped, if desired, by restraining the rod It in the position shown in the figure, when the impulse wheel is opposed by the plain part of one of the discs. To prevent overwinding, there is a stop-work limiting the winding to 5 turns, аш! of course the barrel arbor has a ratchet and click.

Tnc instrument which I make this description from Is by JPaquet, of Paris, and made according to Maelzel, who invented the metronome in 1813.

H. H. L., Manchester.

ROTATION OK THE EARTH, &c.

Sih.—I have lived long enough to feel convinced that under the head of "Original and Independent Thought " a great deal of original nud independent nonsense is uttered; but I cannot help acknowledging that if the hearers of "Parallax" aud charlatans choose to believe the rubbishing theories of those "gentlemen," they are perfectly at liberty to do so. If individuals supposed to be sane choose to accept the theories of these "gentlemen," by all means let them. If they cannot ask themselves tbe simple question " What advantage do Mr. Proctor and the other astrouomers gain by telling these ties," (" fraud and falsehood " are the choice expletives Mr. J. Hampden uses), let them remain in their ignorance. Burning the candle to give Ibctn light is waste of time, life (for life is not too long), and money. But I agree with you that it is not advisable to smother Mr. Beardsley's letters; let them have the light of day by all mean». By the way, I should like him to explain the following fact :—Lost winter, while an unmistakable East wind was blowing on the surface of the earth, I saw dense clouds travelling from S.W. to N.B. cross the moon at the rate of 10 miles an hour. How does Mr. В account for thU?

With regard to Mr. B's. little "difficulty" about a strong south wind infringing on the peaks of the earth, p. °0, he need not be alarmed. It would have about as much effect ne Mr. B. could produce by blowing with all his might against the side of a cog wheel in rapid motion. Mr. B. does not say anything about the extent of surface on which this strong south wind is to blow. I imagine it would have to be a very broad "belt " Indeed to induce the peaks of the Himalayas to deviate from the path they describe.

Does not Mr. B. tbink it would be advisable to give us bis own theory Instead ol picking imaginary hole« in the received explanations of mnndane phenomena? Of course so learned and talented an inquirer into the mysteries of Nature has not adopted his theories without laborious and painstaking research, and has arrived nt a solution of tbe various "difficulties"

which is doubtless satiifactory to himself. It Is of course not impossible that Mr. Proctor is wrong ; but then again It is not even probable that Mr. Beardslcy Is right.

I have only recently discovered that Mr. Hampdea founds his opposition to modern "astronomers " on Scripture testimony. Wbat a marvelloue misapplication of a wonderful book

Estpropitttm, stuUitiaalionan"vilia" cerneré,oblirisci suorum. Saul Ktmea.

COMMERCE AND TRADE.

Sib,—As "our" journal Is the only one that circulates In every workshop and amongst all classes of workmen, I should like, with your permission, to elicit some opinions on the above subject. To make tho matter plain, I will put tho question in the form of a short extract from tho "Statesman's Year-book for 1870": —

"The sum of the imports into the United Kingdom for tbe year 1868was £Д>»,в93,Л08. . . . Meanwhile the exports for the year 1868 amounted In all to

£179,677,812 We are exporting less, and

importing more. . . . The question arises, What sort of ' prosperity' does this indicate 7"

1 venture to think the answers to this question will be of very great Interest to a majority of our readers: and certainly no journal has a better opportunity of eliciting ueeful Information on this important subject than the English Mechanic. Of course politics are tabooed, as well as theology, or our '• happy family " cage will become a den of "roarlug

lions/' SAUL К.ГМЕЛ.

A LIBEL ON BRITISH WORKMEN

Sir.—I wish to call the attention of English mechanics to the following extract from n leader iL the Globe of April 20. The writer say»:—" Our notions of education are somewhat crude and superficial, aud we are a trifle too proud of our barbarous alphabet and our Imperfect multiplication table. Those men whose work is visible In Westminster Abbey spoke belter English than ours, although they were unable to write it; and their education, being moral as well as intellectual, caused them to do good sound work, Instead of 'scamping 'everything in tbe modern fashion. They loved their work, whilst too many of our modern artisans hate theirs. Why they do so is a wide question. It is not wholly their own fault; It Is the vice of an age in which betting men and stockbrokers are the very cream of society il) The men who built our cathedrals had a share iu the structure a» complete a» the architects. But the workmen of to-day are very much like other fungous growths of the time. They care for what their work will produce, not for tbe work itself.

. . . The thing now deemed desirable to be learned Is how to make the most money with the least expenditure of labour."

Now this is a deliberate and unjustifiable libel, for if the writer had really any knowledge of the matter on which he writes, and of the world in which he ( lives, he would have heard of a writer named John Ruskln, and if he had read his work» he would have known that it is mainly through the system of paying by the piece that so much of tho work of the present day is "scamped." To »ay that '• everything" Is "scamped " is to say that wblch is notoriously untrue; for although there are doubtless hundreds of houses "run up," that is no proof that "good sound work" is not put Into hundreds of others; and I have not the sllgbteet doubt but that Mr. G. G. Scott knows where to find masons and sculptors lu every way worthy to build another " Westminster " or another "St*Paul's." To say that the men who built Westminster Abbey spoke better English than we do, and that they did better work because their education was "moral as well :is intellectual" does not say much for the "advance ef civilisation " or the " power of the penny press." If their language was so much " better than ours, why does not the Globe adopt it?—possibly it might increase its very limited circulation. It is no palliation of the Globe's offeuee to say that it is not "wholly the fault" of the workmen; for anyone who looks dowu the list of tenders offered for any large building will see that in 'J cases out of 10 the " lowest tender" Is accepted, although it is very likely less than ha{f tlie amount of the highest. .So long as "consumers of labour" adopt these tactics, so long will builders use interior material an,d Inferior workmanship. It is »imply nonsense to say that the workmen of to-day care merely " for what their work wdl produce." I can go and buy an inferior watch at a low price; and I can also get a " good sound" article at a fair price. The labourer Is always worthy of hie hire; and it would be ridiculous to charge the watchmaker who asks a " good," price for the produce of hie labour with liking his work only for what it will produce. Tho same'argument applies to alt the relatione of lite, and one number of tho English Меспамс gives the "lio direct" te tho assertion» of the Globt: for there "he who runs may read" that men do love their work for their work's sake. The sentence about speaking "better English" shows the amount of knowledge of the whole subject possessed by the Globe. seeing that tbe men who built and rebuilt the extant West Minster lived at intervals between 1231 and ШОУ. (Tbe foundation stone of the present building was laid by Henry III., in 1221, since which time it has been "added to" up to the reign of Henry VIL Portions have been re-built so late as 1809.) But possibly the best reply to such ridiculous "bunkum" is furnished by an earlier sentence In the very " leading article " from which I quote. "Such nonsense is not worth serious criticism,indeed, it is easily explicable from the fact that Easter 1» a holiday for journalists as well as politicians, and that newspapers must be tilled, even though the better brain< of tbe establishment are away iu the country." It is a great pity the writer in the Globe oould not все that a " pen " is a weapon that "stabs" both way-, Certainly the "better brains" were absent on tbi.-. occasion. Saul Hy.mea.

CHICORY AND STARCH.Sib,—From unavoidable circumstances, partly connected with the business of this time of the year, I have been unable to pen flown tho article on starch; but such as it is I now semi it to you. In the number be tore last of our Mechanic, there is nn article from the Food Journal in which it Mated that chicory is procured from the endive root. 1« not this a mistake? The root of the Cirhorium intibm, I., has been used for that purpose, aud I should have thought the endive would not have been likely to be used in preference to chicory plant. There are several substances having the name of starch, aud which chemists tell us are closely related to each other In chemical composition, —namely, Iceland moss starch, lichen starch, licheain. found In Iceland moss and other lichens: animal starch, found in the liver aud placenta; inulien, found in the root of the elecampane, dahlia, and Jerusalem artichoke: aud the ordinary starch as we find It in rice, Ac. This latter substance is that which forms the subject of the present article. Starch occurs In the form of grains of very various Bhapos and sizes, occurring in the cells of various parts of plants, most frequently in the seeds, roots, and *tcms, and also said to occur in the receptacles and pollen of flowers. These grains resemble each othuriu one particular, — namely, a point which, from/lts shape and position, is often characteristic of the kind cf grain to which it belongs. In viewing starch under the microscope, as they lie in their containing cells, I think it is impossible to avoid the conclusion that this point is the point of attachment of tho grain, and forms tho nucleus around which the starch grain forms; for all the parts of the grain are relate.1 to it. Starch, under the microscope, usually presents the appearance of partial or complete curves -surrounding or related to the above point, or liilum, as It is called; indeed, it would appear as if the gram consisted of a number of coatings, their common meeting point being the hilum. This structure is rendered more apparent in the following experiment:—Place a little arrowroot or potato starch on a glass slip with a little water, add a minute quantity of tincture of iodine, let it bo a few Beconds, then soak up the moisture with a small piece of blotting paper; placo a thin cover of glass over the starch left on the slip, place on the microscope stage—a power of {ia. focus will do very well; just drop a little strong sulphuric acid oarefully by the edge of the glass cover so as to let it run between the two glasses, and cover the starch, 'the layers will swell out from the hilum like gelatinous bags, the light blue communicated by the iodine serving to render them visible. It would seem that the outer covering slightly differs in its properties from that contained in tho interior of the grain; being coloured violet by iodine, a-* seen both in the whole grain, when the outer surface shows the violet; aud when starch Is heated for a short time in a large quantity of boiling wator, and allowed to settle, tho white sediment gradually deposited, separated from the liquid and examined by the microscope, shows the appearance of a gelatinous membrane, and, when tested with iodine, shows the same or similar violet colour to that which appears on the outer surface of the whole starch grain. The latter may be soaked for almost anv length of time in cold water without apparent alteration; but if potato or arrowroot starch are pounded in a mortar, some of the grains will be seen crushed in various ways, tho broken edges being covered with sharp angles. If rubbed up with a little cold water, and the liquid Altered, we obtain a white opalescent liquid, which deposits no sediment, and no filtering will clear, evidently an Imperfect solution of starch; treated with a proper quantity of tincture of iodine, it ahows the same royal blue as perfectly dissolved starch. This is obtained by boiling a small quantity of starch in a large quantity of water, when a perfectly clear liquid may be obtained by filtering, containing a small quantity of the starch in a perfectly dissolved state, which is shown by the royal blue above mentioned, being produced by the .action of iodine. Kice starch treated In the same way gives similar results, only the smallness of tho grains render it iucouvenieut for experiment. The iodide of starch produced is insoluble, or very slightly soluble in water; for if a small piece of solid iodine is dropped into the solution, the blue compound forms around the piece of iodine, while the liquid alone remains in appearance clear, though If the iodine be added in form of tincture, the blue com* pound never settles from tbe liquid in which it is diffused. Dry starch grains treated with iodine vapour (placed in a closed bottle with iodine) gives rather different results. The mixture commonly sold as arrowroot (arrowroot adulterated with potato) is coloured yellow sand ; starch from the underground stem of Calynteaia septum (wild convolvulus) light brown, with all the rest, I tried—namely, Indian corn, wheat, horse radish, rice, and fenuel. I obtained a violet after about a days exposure to the action of the vapour; all showed a violej, colour on being dropped into water. Starch is precipitated from its solution by solution of galls, and partially by acetic acid, some being precipi'uted and some remaining dissolved. The action ot acids, Ac, on starch is so well known that I may well leave out any further remarks on that subject, But in a future paper, it desirable, I may say a few words on tho office performed by starch in nature, the nature of its production, and the means used to detect its presence. J. C.

SLOT CUTTING.

Sin,—I beg to tender my thanks to our obliging 41 J. K. P.*' for his reply on the above subject. 1 had, of course, no wish to put him to the trouble of searching the back volumes, and was not unreasonable enough to expect him to do so. I have now looked through the "Notes and tjuories" of tho whole scries, but, I regret to say, without success. The question was, therefore, probably embodied in some longer communication. What the writer required was the means of cutting, in tho lathe, the alots in the back part of pianoforte keys through which brass pins pass that hold them in their place. I looked out for an answer to this question, because it struck mo that the solution would indicate a ready, expeditious, and accurate motle of cutting mortises in small articles of joinery. I almost fear the tool suggested by "J. K. I*.'1 is more adapted for metal than wood, as the cutting edL'<* would bo scarcely keen enough for the latter. Nevertheless, 1 shall try it. I

was unaware of the shortness of the period during which "J. K 1*." had been a contributor to the English Mechanic, aud am really amazed at the large amouutof valuable iuformatiouhe has afforded in that time. K.H.C.S.

THE WORKMEN'S INTERNATIONAL
EXHIBITION.

Sir,—In answer to those of your readers who have uot received any answer to their letters to me, I beg to say that although I am perfectly willing to afford them all the information and assistance in my power, I cannot afford them stationery and postage stamps as well, my services to the Workmen's International Exhibition being honorary.

They will therefore please to understand that the reason why they have not received answers through the post is, that they omitted to send stamped directed envelope for reply.

Robert Bubuess, 22, George-street, Oxford-st., W., Local Sec, W.I.E.

FISHING RODS AND FISHING.

Sir,—I have, as an amateur, made a good many salmon and trout (ly rods, and have tried all woods except the one mentioned by " The Harmonious Blacksmith." What I always aimed at, was lightness and strength; if I had this, I was pretty certain to havo both elasticity and firmness. After trying all woods, I succeeded in making-a snlmonand a trout rod which pleases every one who handles them { the first was 18' o* long. Mem el butt, hickory middle joint, lancewood anil bamboo top. weighed *Jlb. Soz., and pulled out last season many a fine 15 and 2(>lb. salmon. The trout rod is 11' <V lot.g, ash butt, hickory middle, and lancewood and bamboo top, weighing I loz. without the reel, and seems in tho hand like a willow wand. I should like to see some matters relating to shooting and fishing, now and then in your journal ; these are always interesting to both rich and poor, aud when I am thus in the field, or more properly, the water, would like very much, if some of your sporting readers could give me a wrinkle how to catch mullet. I have tried them with every bait I can think of, from slob worms to boiled cabbago, aud find myself circumvented. They are to be seen in large numbers during the summer and autumn months,lying motionless iu the timber ponds, many of them 10 and V-Mb weight, allowing one to go within a few feet of them, if quietness prevails, but the moment a lino is thrown, away they go. Vivis Spkrandum.

A CORRECTION.

Sir,- I am afraid I must plead guilty to having committod a slight inaccuracy in the expression of the formula referred toby G. Firth, if it appears iu tbe last volume, as stated by that gentleman in your last impression. Anyone versed in astronomical formulae and expressions would see the error at once, and bo able to rectify it, but to those who have not experience in those matters, I doubt not it is sufficiently puzzling. Of course by /\, is not intended the log. dist. but the dist. The formula will then offer no difficulty.

r = 0-7215

A = 0-4210

K = 0-W1"

Sun. 2 13S5 = log. = O-32U0a

9R 111838

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COTTON SPINNING.

Sir,—Many thanks for the quick replies to my inquiry respecting draught in carding engine. I quite agree with "B. W. Roshdale.'* that the rule I quoted (found iu several small publications) does uot give tbe draught sufficiently accurate, but that the draught should be tho "difference botween surface speeds of the HrBt, or feed rollers, and last, or delivery rollers.

"Factory Lad" will perceive that the difference between traverse of doffers and ealleuders was intentional, showing tho difference between the two speeds •f delivery.

DRAWING FRAME ROLLERS.

I should set these as follows :—

Between 1st aud 2nd 3.91

„ 2nd and 3rd 180

„ 3rd and 1th 1-20

Total draught 0i»3

The best and cheapest publication, with plates, on Cotton Spinning, which I have met with, is one by "Kurt Neete." It costs 4s. or 5s., and may bo had 'rom John Heywood, Manchester, or Sfmpkin and Mar-hall, Loudon, styled "The .Mule Spinning Process." Mutual Improvement.

TUB SALTAIRE LATHE.

Sir,—Your illustration of Mr. Salt's lathe must have delighted many of your readers; but thepoor description pinned to Its tail must have equally disappointed them. Your amateur turning friends will be much puzzled to know how many of the self-acting motions are obtained, to say nothing of a host of other intricacies in such an elaborate and costly piece of work. Very complete it may be said, no doubt, but uot tbo most complete lathe in exlsteuce by many a bit. A lathe designed and made by Mr. Smith for his own

Erivate use Is n far more complete machine, and it may e said without fear of contradiction that the '■ Sal

taire-Ward our-street Lathe" is an offspring of Mr. Smith's ** Jersey La tho," aud I hope at some futuretime to send you a few blocks of rosetto work, will* photographs of other things done in the lathe that will Bet the wita of the fancy turning fraternity to work—a lessen not easily accomplished.

Your correspondent "J. K. V." does not seem satisfled with the description of the Saltaire-Wardourstreet lathe, inasmuch as it does not mention 3Ir. Kvana as tho maker. He also states that Mr. E. did not make the overhead motion, only did a few alteration?. If these alterations consisted iu discarding certain parts and substituting his own improvements, it is very questionable whether it would uot have beeu belter let alone, and when "J. K. IV states that he know* a great part of tbe lathe made at Saltaire was put on one side and entirely re-madc, he states, I think, more than he can prove. Will "J K. 1*.** be kiud enough to name the parts that were laid on one Bide? I believe a double crank shaft made at Saltaire was discarded and substituted with one of Mr. Evans's improved single crank shaft—a very doubtful improvement indeed; I also believe that tho standards bed, heads, wheel, and other parts, auch as lead lug screwsaddle, overhead motion, Ac, was all or nearly fiuismsti before Mr. Evaus had it, with the exception of polishing, and that the same hnd not beeu discarded. I am uot aware that there are any ot Mr. Evans's improvements in tbe lathe except the slide rest and single crank shaft, both of which were directly opposed to tho designer's notion of lathe making.

A Natural Flat.

ASTRONOMICAL.

Sib,—I am sorry that ■■ Veritas" took exception to my using "qualified" Iu my note; I did so because X do not profess to bo so myself, not^being a mathematician, but only working from the formula given iu the books, and as " Veritas" had used quantities (a* coversiue of arc) not mentioned by any authors, L wished to know if he was right in doing so, or whether ho was misleading any of your readers taking interest in the subject: and he also deduced the mean horizontal parallax from the distance, and notthedistance from the mean horizontal parallax, which lit. I believe, the only data in conjunction with the equatorial gemitliumtttT of tbe earth for determining that distance.

Thauks to " It H." for his information from the

"Phil. Trans." He Ib not perhaps aware that all

astronomers have agreed that that determination was

too small, aud that the eunatorinl horizontal parallax

8**1)

is now considered to be about > from observations

H D/i ) of Mars at opposition, and also from tbe velocity of light, and that this value is also supported from a rediscussion of the original observations of the transit 'of Venus by Cooke, recently communicated by Mr. Stone to R. A. S.

I submit that the equatorial semi-dirtmeter of tbo earth is the proper quantity to use, the mean semidiameter being tbe radius of the earth in Iatitude4r>°-Vand is only of value in determining the local parallax of any object from the geocentric position.

If Mr. Ueardsley is the possessor of a telescope, will he allow me to suggest an analogical teBt as to the earth's rotation and sphericity? If he will observe the sun for some days in succession he will see spots traverse the surface from cast te west; Jupiter or Mars, for some hours, markings traverse the discs in the same direction. Now if he will allow that these spots and markings arc actual features of those bodies, he must also allow that there is motion on an axis, and as the object always maintains a round disc, this proves that they are spheres, as If merely circular discs, as they revolved they would alternately show n* circles, then as ellipses, and finally as thin lines of light, according to their thickness. If the sun and the other planets are spheres, why the earth different * Also to consider that a sphere gives the largest surface with a given diameter, further, that it is the most convenient form for oceanic or terrestrial communication in any direction. I think he must allow this as strong collateral evidence.

Allow me to suggost that your space is too valuable to be taken up by mere verbiage whether "harmonious" or otherwise, and that useful information would bo more acceptable to the bulk of your readers thau personalities of any kiad. S. B.

THE SUNFLOWER, kc.

Sir,—I have read the communication of "Tautau" on tbe many useful qualities of tbe sunflower with much interest, and have pleasure in transcribing the substance of a late address on "Plants as Sanitary Agents," by Mr. Ingram, at Leicester. The lecturer explained how plants and trees absorbed tbe moisture from the earth, which would otherwise appear in miasmatic vapours. Vegetable action produced oxygen and freed the air from taint, so that the multiplication of trees, shrubs, and plants increased the vital principle of the air aud helped to get rid of Us impurities. All trees arc of course not alike iu taste and constitution. Those which are deciduous, with large woolly or hairy leaves are not suited for towns; the particles of carbon which float in the air, re-ting on the leaves, often destroy them. Fines and firs require a pure air. The lime, plane, sycamore, elm, and chestnut, are amongst the trees that will thrive in towns. Low. marshy lands are greatly improved by heavy cropping. London sewage has made the r>oor bandy wastes of Barking Creek wonderfully fruitful. Vegetation seeks support, and seizoa upon the pabulum within it* reach; nothing, for instance, is too gross for a hungry and healthy vine. A singular fact wan adduced iu proof of the power possessed by plants to neutralise coxiuus exhalations. Tbe observatory of Washington is situated in a dead marsh, the result of which was, that the assistant astronomers were killod off wholesale. Suutlowors were sown all round, and they reached their greatest luxuriance at the time when the fever was most rife; and the happy result was, that the fever disappeared, whilst the plants nourished ou the poison that had committed such havoc. It was further suggested by Mr. Ingram that

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