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STOKER'S IMPROVEMENTS IN DIRECTACTING STEAM EÎ.GINES.

rilHIS invention, patented by John Ntorcr, of Í Peekskill, New York, U.S., relates to certain improvements in that class of direct-acting engines in which the valve's motion is effected by the action of the pistons working in the main steam cylinder, and in a pumping or blowing cylinder connected therewith upon a tappet rod or pin which projects through the heads of the said cylinder and controls the valve motion of an auxiliary cylinder, the piston-rod of which is connected with the slide valves of the main steam cylinder. The improvements consist in the arrangement of an adjustable slide in combination with the lever which transmits the motion of the tappet rod to the slide valve of the auxiliary cjUnder (and which maybe termed the valve

cylinder, in such a manner that the slide valve or
slide valves of the 6aid main cylinder are kepi
from slammirg if the engine is worked rapidly-
Further, in the arrangement of a gauge secured to
the head of the main steam cylinder, or to that
of the blowing or pumping cylinder, in such a
manner that the distance bçtween the piston or
plunger when it readies either end of its stroke
and between the cylinder head can always he
observed, aud the valve motion can be regulated
in time to prevent injury.

Pig. 1 represents a longitudinal section of this
invention; Pig, 2 is a transverse section »f the
same ; Fig. 3 is a detached longitudinal section
of an auxiliary cylinder which controls the
motion of the slide valve or slide valves of the
main steam cylinder; Fig. 4 is an end view of
¡ the same.

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ever) in stioh a manner that the time occupied by the motion of the said slide valve can be accommodated to the velocity of the motion of the main piston or pistons, and that the said main piston or pistons can be kept from slumming against the heads of their cylinders. Also in the arrangement of л friction clutch in combination with the valve lever and adjustable elide, in such a manner that the said lever is permitted to follow the motion of the tappet rod after the valve of the auxiliary cylinder lias completed its stroke, und injury to the mechanism is prevented. Further, in the arrangement of a double exhaust in the auxiliary cylinder, which controls the valve motion of the main steam cylinder in such a manner that the exhaust from either end of the said cylinder can be easily regulated, and the valve motion can be rendered easy. Also in the arrangement of a rubber cushion secured to the valve iod, und acting against stationary plates provided with corresponding sockets in combination with the valve motion of the main steam

WRIGHT'S IMPROVEMENTS IN PADDLE WHEELS.

THE objects of this invention (patented by Lemuel Wright, of Brooklyn, U.S.), are to prevent concussions as the buckets of the wheel strike the water, to avoid the swell or sidewise wave from the paddle wheel, and to lessen the lifting of water as tho buckets leave the same. These objects are attained by placing the buckets diagonally (at about 45") to the axis of the shaft, and arranging them in ranges or rows around the wheel, the buckets of one ruuge standing atan opposite inclination to those of the next range, and the buckets of one range placed intermediate to those of the adjoiniug ranges. In the drawiug a is the shaft of the paddle wheel; b b the anus connected to the shaft a and to th¿ rings d in any suitable manner, «id to these arms the buckets с are attached, tho whole composing the paddle wheel. These buckets are to be arranged in two, four, or more ranges or rows rimming the wheel, each range standing at an opposite iucli

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inclination of each rango of buckets run in an opposite direction, each of said rauges forms a seotion of a many-threaded screw, one range corresponding to a right-handed screw and the next toa left-handed tcrew, aud the buckets of one range standing intermediately to those of the next range, the water, instead of receiving a back ward movement as soon as struck by the buckets will be thrown against the buckets of the next range, increasing the resistance or bold of the buckets on tho water, preventing the side swell in a great measure, and finally passing the water directly to tho rear. The outer ends oí the buckets are shown as projecting beyond the edges of thearms or rims of the wheel, and each backet, coming to a sharp point. Instead of being so fornjed they may be made with a circular or straight outer edge, as shown at f g by dotted lines, Fin. 1, or if desired the buckets might bei flush with tbe rims of the wheel. Л paddle wheel made in the manner above set forth possesses, many advantages over the wheels luretofore use»! The diagonal position of the buckets prevents concussion as they enter the water, and gives to each of the buckets the properties of a section of a screw, so that each bucket commences to take a hold upon the water at the point of entering, and continues during its entire passage through the water to act against the water, and daring the latter part of its passage very little or no water is lifted, and as the lateral tendency of the water as thrown by the buckets of one range is counteracted by the next range of bucket?, the water is passed directly to the rear, and the heavy side swell caused by the ordinary paddle wheel is avoided. The wheel acts equally well or nearly so when going in either direction, and the wheel may be immersed to a greater extent than the paddle wheels heretofore made without inj urionsly affecting the same, thereby increasing the hold of the wheel on the water, and the paddles are not liable to be injured by the waves.

CLEMENTS' ECONOMIC LUBRICATOR.

WE illustrate Clements' economic lubricator, now so well known that it scarcely needs our description, but as the makers, Llewellins and James, of Bristol, have latterly so moditied and improved it as to make it of more general adaptation, we have thought fit to notice it here. This steam lubricator, or impermeator, vie believe to have been the precursor of the many now before the public. It was first introduced some years a£o in the A form, with a hollow or curved back, as shown in our left-hand illustration, so that it might be fixed against the steam pipe by means of a band; the advantage in'tbis bein^ that the heat from the pipe always keeps the grease in a fluid state. Latterly, however, the forms have been varied so that it may be used in any position, vertical or horizontal, and either for marine, stationary, or locomotive engines, one of which—the C form—we illustrate on the right hand. To briefly describe the lubricator, we may gay that A is the body or grease vessel, to which is attached a gauge gins? E; C is the charging valve ; D the air Tent; P is the steam

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PROCEEDINGS OF THE ItOYAL ASTRONOMICAL SOCIETY.

At the meeting of the society (W. Lassell, Esq., in the Chair). untheftth hut, only three papery were communicated—one from Mr. Hind, giving an account of an investigation recently made by Mr. Plum me r on the orbit or the comet of 1683, another train Mr. Tebbutt, Jan., of New Sooth Wales, on the lunar eclipse of January 17, 1870 i and the third from Mr. Birt, giving his result uf tho observations on the lunar crater, Plato.

Mr. Hind said that attempts had been made to represent the path of the comet of 1683, both by a parabolic and an elliptic orbit, the former by Halley, and the latter by Dr. Claussen. Dr. Claussen's investigation had led him to conclude that the comet moved in an ellipse of 1HH yean' period, and that consequently the return of the comet might be expected about the year 1871; hut the

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computations of Mr. Plummer did not leail him to a similar result, but tended to show that a parabola represented the observation with a greater degree of accuracy, and that there was no reason to believe that the comet would return to the neighbourhood of the sun in a few years.

Mr. Tebbutt'* observation of the lunar eclipse contains very little information peculiar to lonar eclipses. The effects of the penumbra were strongly marked, and the usual copper colour of tho shadow was noted, which colour wan al.su noticeable on some light clouds in the vicinity of tho moon. Tho ocoultattons of several stars of the seventh, eighth, and ninth magnitude were observed, and the times of disappearance and re-appearance given. The telescope employed was of 3J-inch aperture, with.a power of about 30.

Mr. Birt gave the result of a twelvemonth's* watching of the crator Plato, with a !>-iiich refractor. The result has been to observe and map many spots ou tho lloor of Plato, hitherto unobserved, with the changes that httvo taken place in their number and position, and Mr. Birt expressed his intention of continuing to observe the moon, which he had little doubt would lead to valuable results.

The President then observed that there was a possibility that Government would furnish a ship, similar to the Himalaya, perhaps the Himalaya itself, to carry observers to Spain to observe tho total eclipse of December 22. 1870: but before any certain result could be obtained. It was indispensable that the society should kuow how many gentlemen contemplated a voyage, aud what accommodation would be required, and whutlustru mental means the intending observers could command. Xeres, Syracuse,** ml Oran (on the African coast), appeared to be the Btations that offered the greatest facilities. Oran, on French territory, could be left to tho astronomers of that nation; but Gibraltar being the seat of an English garrison, it was desirable that the English should send observers to that port. To supply effectually all the departments of astronomy, and to employ a complete set of instruments, about twenty observers would be needed at each station. The President concluded by Inviting observations and discussion on this interesting subject from those Fellows present, and announced that a circular would bo despatched to waru other Fellows who were not present, hut who were likely to take part in the expedition.

The Astronomer-Royal, who rose amid some applause, said that though he was not In the confidence of the Government, he might open the discussion the president had invited by pointing out the probable assistance the Government would render. The Astronomer-Royal brietly traced the course the moon's shadow would take ou the earth's surface. It would not touch any of the Atlantic Islands, Cadiz and the neighbourhood of Gibraltar being the first possible observing station. Gibraltar offered considerable advantages, being on British territory, easy of access, and possessed of considerable matters of interost Oran and i t> neighbourhood, which was likewise an important station, could in safety be left to the enterprise of the French. Afterwards the shadow rests on Sicily, and passes over Syracuse, a locality that the Astronomer-Royal had never visited, and he was unprepared

to say what accommolation Syracuse could afford. From Sicily the shalow paaaM over a desolate part of Greece, over the Black Sea, over the Crimea, and midway between Balaklava aud Sebastopol. To what part of this line individual enterprise might carry individual observers, Mr. Airy could not uudertako to say. The result of the inquiries he had set on foot was that the Government would give no assistance in money, but possibly a vessel might be allowed to carry observers as far as Gibraltar or Oran, as the observers might of themselves decide, though possibly Catania, on the eastern side of Sicily, might offer better chances of transparent atmosphere than elsewhere. Mr. Airy did not think it desirable that a part of the observers should bo left in Spain, and the ship employed in carrying the remainder to Sicily, not on account of the demy in time to the ship, hut the delay occasioned to the observers, being left a week sooner than needful, and de>tained a week longer after the eclipse, before the vessel could return for them. Mr. Airy conjectured that the peculiar Bsason of tho year (the winter solstice; would deter many from going, though he had no doubt thai those who faced the storms of the Biy of Biscay, and the probably uupleasaut passage, would be well rewarded by the sight of the eclipse. Mr. Airy iusisted, in the most positive manner, on knowing the number of persons who intended to take part in the expedition, as no positive answer could bo obtained from the Government till such data had been furnished as a b.isi- for further progress. Tho Astronomer-Royal then treated of the subjects of observation during the eclipse, uud the necessity for organisation of the observers, more especially as the time of total otmcuration was short. Mr. Airy had no doubt but that the 'Corona" would receive the greatest degree of attention from all observers; and, to anyono who intended to make observations of it, a knowledge of the phenomena of polarization was indispensable; and it occurred to him (Mr. Airy) that on this point there was a great amount of ignorance, and, before organizing a band of observers to use the polariscope, it would be necessary to teach them how t« use it, or at least to examine if they were competent to observe with this Instrument, none being more capable to give Information on this point than Professor Stokes. With regard to favourable weather. Mr. Airy would take tho opportunity to ask those present who were acquainted with tho climite of Gibraltar, by experience, to favour tho socioty with their opinions, and begged to introduce to the attention of the«ocioty,

Lieutenant Brown, who said that, being called upon unexpectedly, be could not furoish the society with accurate information, though the general impression ot his mind, derived from a stay of six wiutcrs InGibraltar, was that the season of the year wai eminently favourable, and that, had astronomers 'he power to choose the time of the year most favourable for witnessing an eclipse, their choice would probably bavo fallen upon the month of December. As a photographer, he remembered that the lights and shades of his copies were not Bo strongly marked as in the summer months, but were beautifully soft He doubted whether Gibraltar could find accommodation for such a largo party as would probably visit it, but Xeres could ac^ummodato a portion, and there were plenty of gentlemen ot bUlUcicot lovfl of aaionoe »'. Gibraltar W'jo would be pleased to mako the necessary arrangements to receive the deputation of astronomers.

Admiral Omœan*y coincided in the remarks that had fallen from Lient. Brown, and believed Gibraltar preferable to Syracuse, and cooid afford snJBcient accommodation

The Presldonv wis very gratified to boar an opinion so favourable from :>ach eminent authorities, and although be had been of a different opinion* he yielded most wiltJnjrly to those of greater experience.

Mr. Warren de la Rue called attention to the necessity of observing with the greatest accuracy ihe corona, which might consist of two or threo phenomena, ani ho trusted that tho attention of astronomers would be given to that portion of the corona between the prominences, which had always been seen very brlttlant. Mr. De la Rue conjectured that this belonged to tile sun, as tho advance of the moon covered some of this brilliant portion, and disclosed others, but any doubt on tho subject ho trusted, wonld be cleared up by attentive observation.

Mr. Vignolles informed the . society that ho had learnt from the Vice-President of the Cortea that he <the Vice-President) would be very buppy to render all tho assistance In Uis power to astronomers that should visit Spain on this occasion, cither in providuag accommodation, orconvcyiug them into the interior.

A Fellow asked what length of time would probably be consumed on Й10 journey, and in making tlie necessary observation's; and whether there would be any attempt at organisation, or each observer loft, to carry cut Ms own design in the manner that seemed to him best?

The Astronom or-Royal replied, judging from the experience of former eclipses, a month would probably ¡-.office, and that a complete organisation was desirable.

¿n the eclipse of 18UU this organisation was effected on oard the Himalaya, but if intending observers sent in their names and instrumental meant, euch an organisation might be effected sooner, which was desirable. Mr. Airy said that among tho inst.nimeut.-t of the Royal Ob«ervatory were three 6in. refraatortf. and four 4in., which he had no doubt the Government would allow him to put at the command of competent observers.

Mr. Huggine remarked on the organisation of spectroscopic observers, that a» tbo time»was short, it would be advisable to divide the complota ppectrum between two observers—one to scrutinise for bright lines on the lose refracted half, and the other for bright Hues in the more refracted half of the spectrum. This only referred to tbo

Sirtion of the corona nearest the ¡win» allndcd to by Mr. e la Rue. For the corona more diu tant, a spectroscope might .be employed that should show the whole of the spectrum atone view; and. further, bo thought it neceeaary that each spectroscope should be furnished with threo observers—one to look through the instrument, another to direct the instrument at the desired portion of the sun, and a third to write down the observations: two spectroscopes being required to examine tho prominences, two for the corona between the prominences, and one for tho distant part of the corona, making in all five instrument«, and fourteen observers, or manipulators, for each station. Colonel Strange offered a few remarks upon the necessity of examining the observers in the pecularitles that polarised light presents, observing that if the eclipse took place noxt week, very few observers would be found capable of observing the phenomena—uu opinion in which the society coincided, and he concluded with a few remarks on the connection between astronomical observations and general science and knowledge.

In answer to a question from the President, Mr. Do la Rue replied that the number of manipulators required to niauage the photograpbical department would be five, one principal, and tour assistants. Heneo for the spectroscopic and photographic observations alone, nearly twenty observers are required at each station.

The meeting concluded with some remarks from Mr. Watson on the geographical structure of the moon, which being an abstract theory unsupported by facts or observations, оЯегв little of interest.

Mit. J. NOKMAN LOCKYER ON THE BUK.

Oís Saturday, the 9th Inat., MY. J. Norman Lockver, F.R.3., delivered his fourth and closing lecture at the Royal Institution, on " The Sun." In the course of the lecture he observed that when the flume of a common candle is examined in the same way that the erta is observed with a spectroscope, it is found that when the flame is injany way disturbed, gases of different kinds are thrown out from its interior towards its exterior. In like manner, when from any cause disturbances are set up in the sun, there are storms or outbursts of luminous iron, magnesium, barium, and other vapours. It is evident, therefore, that there arc layers underneath the external envelopes of the sun, portions of which layers become visible to us whenever there is the least disturbance. Spotsbeing depressions in the external envelopes of the sun, it follows it bat an examination of the aolar spots brings the astronomer nearer to the centre of the sun than docs the observation of Auy other part of the orb. On examining the spots with a spectroscope, a general absorption of the rays of all parts of the solar spectrum is seen, as well as a selective absorption, the latter being especially noticeahle in the so-dium lines. and the greater the pressure of the sun's atmosphere the thicker are these absorption lines. lu order to prove that increase of pressure, without variation in temperature, broadens the absorption lines. Mr. Lockyer threw upon the screen a continuous rainbow-like spectrum of the electric light, the dispersion being produced by means of two hollow glass prisms filled with bisulphide of" carbon. Just outside the slit of the electric ¡intern the light was made to pass tiiroigh a glass tube filled with attenuated hydrogen gas; the tube contained also a lump of metallic sodium. Heat was applied to the bottom of the tube, во as to gradually vtipourise "the sodium, and the vapour was at first, of rourse, densest near the bottom of the tube, rather than at the top. The vapour intercepted none of the rays of the spectrum, excppt » portion of the yellow, consequently a dark band was cut m the yellow purl of the spectrum upon the «creen, hut this band was thickest where the light had previously passed through the denser portions of the sodium vapour. The appearance of this tapering dark line consequently proved that where the pressure of the sodium was densest, it broadened the dark line in the yellow of the spectrum. Thus the broader the sodinm absorption lines produced by a sun-spot, the greater is the pressure 4nd quantity of the ictHum atmosphère over that spot. There are now ninny large spots upon the solar dite, and it is a Ycry curious fart that they give scarcely any absorption in the yellow part of A spectrum, showing thereby that the spots are not

alike at all times. There are, in the ordinary solar spectrum, bright lines as well as dark ones, and he thought that these would be found to be the moat unchangeable lines in it, for the dark ones arc constantly varying. The yellow line, so often seen in the spectrum of the solar prominences, was once surmised to be a line belonging to hydrogen gas when the gas became luminous under certain very unusual conditions, hut after many experiments with hydrogen, tried by Dr. Vrankland anil himself for more than a year, they were unable to make the luminous gas produce any such line. It was only on the previous Saturday that, while he (Mr. Lockyer) was examining the spectrum of a solar prominence, he saw the bright hydrogen lines of the prominence disappear nliuosl entirely, while the yellow line retained its full luminosity and length. It would appear, therefore, to be certain that it ts not a hydrogen line ; neither is it a sodium line, for it does not fall at the right part of the yellow of the spectrum. Probably this perplexing line is due to some new substance common in the sun, but not yet known upon earth. A. very valuable paper on solar physics, once communicated to the Royal Society by Mesera, Balfour Stewart, De la Hue, and Loewe, set forth that the photosphere of the sun might be considered to be a plane of condensation, and any changes in the pressure of the plane of condensation will cause very considerable changes to take place in the spectra observed. For example, when the pressure of the plane of condensation of a common candle flame is reduced by the aid of the air-pump, a halo of blue light begins to spread outside the flame as the pressure is diminished, and at last the candle flame will give the epectrum of nearly pure carbon. The F line ofhydrogen varies very much when the pressure is reduced, so this line is a very delicate indicator of the pressure of the atmosphere of the sun. Light is composed of waves varying in length, so that when a prominence bursts out upon the sun, and in the direction of the eye of the observer, more waves are thrown into the eye in a second of time; if, on the other hand, the prominence bo receding with a velocity at all comparable to that of light, the waves will be lengthened out, and a smaller number will enter the eye in a second. This venation in wave-length caused by the rapid motion of solnr flames produces zig-zag and irregular line» ia the spectrum, and by measurement of the diflection of the bright lines from their normal position, the velocity of motion of portions of the solar prominences may within certain limits be deter* mined. The flames often rise or recede with a velocity of from 0(J to 10U miles per second, which, considering the size of the sun. is not a very excessive rate of motion. It seems as if the chromosphere ia the outer limit nf the son, for very little absorption takee place outside it, and there is evidence that the absorbing atmosphere of the sun and the photosphere begin together. Ля to what is below the photosphere, spectruin analysis gives nu information whatever, and he thought that in a sun-spot nstrouoiners never get below the photo* sphere; he considered the apote to be purely surface phenomena. The photosphere may be gaseous, cloudy, or even liquid, but certainly is not solid, lie did aot know the origin ot the continuous spectrum of the sun; a continuous spectrum may be thrown by dense luminous gases, as welt as by white-hot solids; but it is consoling to be aware that it is equally unknown whether the continuous spectrum of a candle flame is due to solid, liquid, or gaseous matter. He would close his lecture with n few general remarks about the nature of the sun. The sun, after all, is nothing but the nearest star; it is also a variable atar, for the spots upon it, as proved by observations extending ever the last 5Ü years, are very plentiful at some periods, and very scarce at other periods; the interval between two maximum periods or two minimum periods, is about 11 years. We are now in a maximum period. There is also some connection between the spots on the sun and the sun's family of planets, for the positions of the planets, more especially of Mercury and Venus, have an influence upon the area «f the spots on the sun. The sun cannot be a ball of fire, for if it were it would burn itself out in a ridiculously short space of time, and there is reason to suppose that it is a hot globe now slowly cooling. If we accept the hypothesis of Laplace, that the sun was formed originslly by the condensation of a tremendous nebula, it is not difficult to imagine that it is now slowly cooling; and as it had au enormous initial temperature to start with, the cooling will go on through untold age*, until at last, having absorbed all its surrounding planets into its mass, it will in the end roll through space a cold dark ball. Afterwards, perhaps, it may clash against another dark ball like itself, and the force of the blow may be proved by calculation to he sufficient to generate light and hr.att a new sun, and other worlds.

RiriOUX'S IMPROVED LIFE-PRESEAVING DRESS.

The inventiou, patented by Kmilc Rihoux, of Paliseul, Baltram, has for its object the supplying shipwrecked people and others with a means of keeping themselves afloat, and, moreover, has the advantage of overcoming the difficulties at

present found in life-preserving dress« made of india-rubber, gutta percha, or like material, as it does not impede the movemeuts of the wearer or atup his uatural perspiration

The invention consists in making dresse.« of india-rubber, gutta percha, or other waterproof material, provided with cushions which form separate and distinct receptacles or reservoirs, and which are filled with air, and suitably arranged and adapted to the human figure, there being no communication between the receptacles, so that if by any accident one should be injared the safety of the wearer would not be jeopardised, as the other receptacles would still be sufficient. In addition to the dress, an air-tight chamber or chamberí. mide of the same materials and on the same principles, thaï is to say, in separate and distinct compartments, may be provided and made of such a shape that if ncceasary the wearer of the dress may ait on it and move himself about by шеапл of an oar. The dress and the riding chamber lastly described may be made of indiarubher, gutta percha, or other waterproof material, and may be provided with pockets for carrying anything that may be necessary.

LETTERS TO THE EDITOR.

[We do not hold ourselves responsible for the opinions of our correspondents. The Editor respectfully requests that all communication* should be drawn up as briefly as poeslble.J

**" All communications should be addressed to the Editor of the English Mechanic, 31, Tavistoekstreet, Covent Garden, W.C.

All cheques and Fost Office Ordere to be made payable to J. PASSMORE EDWARDS.

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I would have every ono write what he knows, and M much as he knows, but no more; and that not in this only, but in all other subjects: Kor such a person may have some particular knowledge and experience of the nature of euch a person or euch a fountain, that, as to other things, knows no more than what everybody does, and yet to keep a clutter with this little pittance of his, will undertake to write the whole body of physieks: a vice from whence great inconveniences derive their original. —Montaigne's fcsisays.

VOICING WOODEN OKGAN FIFES.

.sir,—I feel very strongly tempted to follow the example of a certain chickabiddy who resides in my neighbourhood, and "crow." Ab<*ut a year ago I related that I had heard organ woodtn pipes so skilfully voiced that I could not distinguish their sonnde from those uttered by metal pipes; and, notwithstanding my testimony was corroborated by another correspondent who heard the trumpet calls alternately performed on a wooden trumpet aud on a brae* one without being able to distinguish "t'other from whlsh" by their difference of timbre—perhaps the most severe test which la possible to apply to two pipes, and pretty clearly demonstrating that the differenceofjtheir timbro dependa much more on their voicing than on their material—I say that notwithstanding nil this, i. being only an ignorant, humble amateur, was duly snubbed by professional authority: but, Маулт reritaj, ¿¿с, which ha* been translated for the benefit of us »nclaslioal blacksmiths, äc, by the quaint author of "The Mechanic's Saturday Night." to mean "Truth Is great aud will prevail a bit Being in no great harry, 1 could well afford to wait until truth did prevail; and I now have tho reward of my patience in the testimony of no less an authority than that of our " Adept"— N.B. I don't think even Sir. Kenible will dispute his statement on this matter—that by making a pipe with a circular mouth, bevelled lroin within, we can obtain from It a tone so clear and bright that it surpasses that of the ordinary metal pipe. It even "took In" я practical organ builder—1 do so like to see the practical knowing one« "taken in "—see "Adept's" note to his article la p. *Ш, No. 265, after reading which I was sorely tempted to cry *'Cock-a-doodle-doo;" but In mercy to Mr. Kemble nud the rest of the weaker brethren 1 forbear to utter so offensive an lo p<tan,oaly bftrglng them thankfully to look this very valuable "gift-horse" in its "mouth," and to forbear from slíowiug thoirtown teeth at what may tend to save us part of the cost of organ construction by enabling them to substitute cheap wood for tba'- dear metal which is, or ought to bo, ttu, aud, nUs! co*u a good deal of our tin. Tue Harmonious Blacksmith.

P.S.—If Dr. Dasher has not quite detened his first love—if., pipes, and gone over to the enemy—viz., a reed Hhakeu by tua wlud, perhaps be will say a word for clear bright tone from wooden pipes at moderate ost?

ACHROMATIC TELESCOPES.

Вт,—Will "F.R.A.S.," Mr. Webb. "Sir. Proctor, or any other adept, Inform me if lean obtain any printed account of the performance of Mr. Ituckingham's 91 Jin. refractor-, also that of the 25lti., made by Cook for Mr. Newall? If these deserve the title aplunatlc Mr. Webb's suggestion to put a new OQ to the great tube at Wandsworth might be Improved on by making thu now OG us large as the old oue. and the flint glass thick enough to bear grinding to the required depth to produce the needful curves without making a great hole in its centre, which required a .'''.''■.'■ patch bigger than the top of my "chiumey pot"—1 mean elegant artistic hat—fashion compels me to wear. For Mr Webb's faccount of this monstrous abortion I respectfully tender him my sincere thanks. Well might "rE-A.S." pay, in his extremely neat manner—when he perpetrates a jest it is Invariably a pood one—that he trotted this '«lesco['e was something very much "out of the common." Such a vile OtJ is to me au ogre; but. surely, the tube and the tower may be utilised for another OG of equal din meter, aud such aperture*, besides their value for sidereal astronomy, could we find n place to use them in which the stormy winds do not blow, ought to enable us to see " the man In the moon," presuming ho is " at home," which, considering he can have no present duty to perform towards our "free and independent electors," he probably may be. unless, indeed, his customary search after such of the inhabitants of his native satellite who have strayed to the earth—see the book entitled "De Lunatico luquirendo"—occupies the whole of bis time, and compels him, like other ambassadors, to lie abroad for the good of his country from the time of one general (parliamentary) election until the next, when the calls of duty must become so onerous to him that he is not likely to agitate for the repeal of the septennial act in favour of annual parliamentary elections. The Hakmomoi S Blacksmith.

rLATLNISED GLASS SPECULA FOR REFLECTING TELESCOPES.

Sir,—I am informed platinum, when polished, refleets a larger proportion of incident rays than silver, and that it can be deposited In thin Alms; the existing manufacture of what tire termed platinised lookingg-lasses is sufficient proof. A silvered mirror Ik perhaps yet more liable to become tarnished by atmospheric Influences than one of bronze or speculum metal, but platinum does not readily become tarnished, which liability is one of the greatest objections to the employment of reflecting telescopes, so I would respectfully ask Mr. PurklsB," F.R.A.S.," Mr. Webb, and others who are acquainted with reflectors, if there fs aay practical objection to coating- glass specula with platinum instead of silver, aud if there be hone, how best to do it? I presume, laying it on with a brush, and afterwards heating the specula, as if it were a fictile production, which is the process employed for so called platinised looking-glasses, would not be applicable to specula, for I fear it might slightly alter their form, and not be conducive to correct definition. Tub Hahmonioub Blacksmith.

THE VIBRATION OF THE BELLIES OF

VIOLINS. Sib,—'* E. I*.," p. :i57, Vol. X., cays that I have overstated the mark when I wrote that the belly of a violin could nti vibrate vpKti r>h without overcoming the downward pressure of its string. Now as this oWn. ward pressure never ceases, because the string's of a fiddle vibrate horizontally and remain deflected vertically while they are vibrating, I think "E. I'." will on further consideration, fee that the upward vibration of the belly mitrf lift the bridge, and of course the string)* which are resting on it.

The fact that the belly is propped up by the soundpost no more relieves it from the downward pressure of the strinc* than a plate of lead on the top ot a columu is relieved from the pressure of the superincumbent weight by the column beneath it. The soundpost is simply a column which props the belly, and transfers the downward pressure of the strings to the back of the instrument (the belly bHm' Mmeezcd between the toji of the sound-post and trie bottom of the bridge) ; but this is not relieving the upper surface of the belly from downward pressure but only enabling it to support thnt pressure with le^s distortion. The Harmonious Blacksmith.

COMBIN'KD DRILL. REIMKR, AND TAP FOR GAS MAINS.

Sir,—On page4?:J is the representation of a drill, reimer, and tap combined, or formed of one piece of steel, to which your correspondent "Alachiuator," p. ;>{,«, very reasoLably objects that It would be drilling, rcimlng, and tapping at ouce, and be broken in the attempt to use it. The idea is so good that it is worth carrying out, and this may be done by the very simple expedient of getting rid of the reimer, which is between the drill aud the tap, for if the latter bo the proper size for tho former, it is obvious the hole It makes cannot require to be reimed, but if it be desired to retain the reimer, to compensate for the workman's want of carp, who might grind the drill until it became too small for the tao, and induce the breaking of the latter in the hole, all "that is needed i* to form a cylindrical neck the some size, or rather a trifle smaller thau the largest portion of the reimer, between It and the tap. If this neck be as long as the' uuekneuof the pipe which U drilled, the reimer must huWu the hole before the tap can enter it, and there will be no danger of breuking the latter from the hole being too gmall for it. I need hardly add. that the drill ought to be long enough to perforate the whole liiickncwuf the pipe before the reimer enters the hole, or there will be a Jam.

The Harmonious Blacksmith.

BLUE MAHOE AND OTHER WOODS FOR FISHING RODS.

Sir,—In tho Field of March 28, a correspondent states he has a fly-rod made of the above wood, which, he says. Is at once light, stiff, tough, and very clastic. This combination of qualities renders It especially ftuitablo for fly-fishing rods—indeed for many other purposes. The undersigned would be greatly obliged by being informed where it can be purchased.-Query, can this wood be the blue mahogany of Jamaica I

I have had considerable experience as an amatear fishing rod maker, and I have found the most elastic material yet tried, to be logwood. Hickory, lancewood, ureenheart, aud ash, are commonly employed, and, next to logwood, their elasticity is. I think, in the

foliowintrlorder: lancewood, groeuhcart, hickory, ash. Logwood, although tho most elastic of all, has the great defect, for careless fishermen, of beiujf very brittle ; it will not bear rough usage. Lancewood is much tougher, but is heavy, nevertheless it makos excellent top joints, and lor abort rods, not exceeding ton or eleveu feet in length, excellent middle joints also. Green heart has come into exteusive use of late years, especially for salmon rofls, but it is more brittle than lancewood, and, I think, yet heavier. It may do very well for our president of the Board of Trade, yclept stout John Bright, and other athletic salmou anglers, but I do not like it for a H#tt trouting rod; yet less for dace whipping.

Well selected heart of hickory makes a very fair fly rod, but It is not so elastic as lancewood (not to mention logwood); it has, however, that desirable quality for careless anglers, toughness, and of some kinds of ash, very good fly-rods may be made, especially the French ash, imported for billiard cues. Major Grant, whose apparatus for military cooking excited Bo much attention a few years ago, and who la on enthusiastic salmon fisher, prefers his ashen salmon rod to any other he possesses, behaving used it for several seasons in Norway with great satisfaction, but I suspect its good proportions have more to do with its excellence than its material.

I have been told, very good fly rods may be made of mountain ash, also of wveh elm and of hazel, but having no experience of those woods, I cannot form any confident opinion of their merit*. I doubt if they are so good as the woods commonly used. According to the Field's correspondent, blue mahoe wood is far superior to them all, aud Is not heavy, a very Important consideration in a long rod iu the hands of "our weaker brethren " of the craft; intleoU I eBteem lightness of so much importance, that I had a rod made, whose tap, nearly five feet long, w*s a finely grown and moderately taper pieco of North Carolina cane, with about a loot of split jungle bamboo forming its point. Tho 'middle joint of this rod was also of North Carolisa cane, and its butt was made out of an ashen billiard cue. It was nearly sixteen feet long and so light, that it might be used with one hand. It answered admirably for throwing a long Hue when chub whipping, but its action was not so regular as that of a well made solid rod, probably because the maker had not a sufficient stock ot North Carolina cane of large diameter to select the middle joint from, for it hardly tapered enough—i.e., had rather too much action at itB larger end, where it entered the butt. This is a very common defect in fly rods, especially those made iu Ireland, and if an advantage wheu playing a heavy .salmon, is far from advantageous when throwing a long line for chub in the river Lea, when you are compelled to throw right across the Btream.

The Harmonious Blacksmith.

INCREASE OF INSANITY.

Sin,—There Is a question of vast Importance which I liiivo net seen discussed in your versatile pages—the increase of insanity in this country.

Although, says a writer, there Is Borao difference of opinion with regard to the cause of it, wo <tau hardly doubt that insanity Is great I»increasing iu these islands. It would seem as if the worst of all human diseases was liable to grow with the growth ot civilization, and us if medical science was impotent to stay its progress. This is what the non-professional observer will gather from certain statements and statlstleson the subject, and it is, indeed, admitted to a large extent by medical men In scientific periodicals. Thus, for example, in the Quarterly Journal of Science, just published, l>r. Martin Duncan writes that "the cures of the Insane iu our fine asylums are not more numerous than they were from 174$ to 1814, when the treatment of the insane was a disgrace to humanity;" that " our social state is produciug year after year an increasing amount of insanity more than ever difficult of cure;" and, again, that "there is no denying or explaining away the fact of tho rapid accumulation of intauo persons in all parts of the kingdom." In the Mvdico-Chirurgical Ileriew for this mouth there is an article on the same subject, iu which the writer states that in the course of ten years the number of recorded lunatics has increased 45 per cent., and that the immense additions made to hospital accommodation during the same period *' have been fruitless so far as they were intended as means of bringing all pauper lunatics under proper supervision and under the protection of the lunacy laws—a privilege not belonging to workhouse inmates." In proof of these statements the writer adds that while, during the last ten years, asylum accommodation has bceii enlarged by nearly two-thirds, *' yet the lunatics detained in workhouses in lS6i» were close upon 3000 more than inJ8<)0. At the same time the pauper insane distributed in lodgings have advanced from 51>S0 to ii'J87." Both these journals thus assert the increase of insanity, both declare that the plan of large asylums has proved a comparative failure and Is inimical to recovery, and both are in favour of placing pauper lunatics in cottage homes, as is done iu some parts of Scotland and at Ghcel, but under a careful system of registration aud supervision. Dr. Tuke, writing to tho Journal of Mental Scierxe, arrives in the main at a similar conclusion. He points out the evils of the cottmro system as exhibited in Kennoway In Flfcshire, but believes that sooner or later it must bo brought more fully into play, and that If improved and elaborated it may bo tbo best way of providing for harmless and Incurable lunatics. Neither of these writers holds out to us any hope that the growth of insanity Is a temporary evil. Luxury is advancing with gigantic strides, ana poverty, with its attendant miseries, grows iu a like proportion. Consumption and scrofula, says the Medico- ChirurgicaI Review, arc increasing throughout the country. A degenerate state of body tends to produco a weak mind, aud tho Journal of Science affirms that insanity is due far more frequently to insullicient nutriment, to poverty, aud to physical deterioration, than to the severe mental * train which Is so often demanded in the present day from the upper and middle classes. The increase of lunacy is not to be found among educated men, but is to be traced almost wholly to the pauper class. In proof of this it is enough to state

that in the five years ending January 1, 1807, the increase of private patients iu asylums was .16, while the increase of pauper^lunatics during the same period was 5040. It would seem, therefore, that in proportion a* we can diminish the pauperism of the country, wu shall stay the progress of the most awful disease which can afflict humanity.

I don't know that a discussion of this question in tho pages of the English Mechanic would assist materially in checking the evil so much to be deplored or preventing its extension. Still, if any one could suggest any means whereby this malady could in any way be diminished, he would, so far perform a public good. J. II. C.

COTTON SPINNING.

Sib—I notice with pleasure the remarks of o " Factory Lad " respecting the abaenoe of anything relating to the cotton manufacture iu your paper. Certainly a very few things have appeared, but no discussion of any moment has followed, considering the enormous number of persons interested and having to do with the mechanical operations aud contrivances connected with this large business.

It is surprising that more has not been brought forward when we think of the number of persous Into whose hands your paper falls in the Lancashire and cotton spinning districts, and of how mrinv different notions and opinions about certain matters connected therewith are held among those engaged.

As " Factory Lad " says, it would be a great advantage if some person would give a description of the machines ana processes of cotton manufacture, an* until such appears perhaps a little discussion may arise from the following question :— A carding engine, whose dofferis 24Jln. in diameter, ha3 on a 2u-tooth wheel, driving 26 ou side shaft, on which is 17-cbaogo wheel into 154 ou feed roller of 21u. diameter. On doffer eod is also 207 through two carriers into 45 on bottom callender, m this .'t*> into 30 on top callender, both 4in. diameter Required the draught?

From several pu. licatlons now before me I find the following rule: —

Multiply the driving wheels on ends of side shaft and doffer together with diameter of feed roller for a divisor; then tin driven wheels on side shaft and feed roller with diameter of doffer for a dividend; quotieut, the draugh i

Is the above rule strictly correct?

Muiual Improvement.

Sih,—*' A Factory Lad" is quite correct in his remarks, p. 69, on " tiitche Masiito,'' and the cotton willow andscntching machines. Evidently "G. M."d d i ot understand what he was writing ;abouf, or he would not have soconfounded tbo two machines. I can alsn supplement "A Factory Lad's'* statement of the estimation in which the English Mechanic is held in the manufacturing districts; it circulates extensively in the town and neighbourhood of Kochdale, ana is patronised by the Kochdale co-operators, at their noble building, the Central Stores, where it graces the tables of their splendid reading and news rooms, and ittpoges are eagerly perused by many of the numerous members who frequent those rooms.

Hitherto matters connected with the cotton and woollen manufactures have been but barely treated #1 la our journal. With "A Factory ^Lad," I hope that in future they will receive more notice, and I think our Editor will acknowledge that wo may fairly claim for those branches of industry a fair portion *f tho space set apart iu the English Mechanic for mutual Instruction. I have seen several questions an cotton spinning which have received no answers, the reason no doubt being that to give the information asked for would make such a demand on your space that persous able and willing to give ii have beeu held bock by the consideration that you would not grant the necessary space.

Some five or six weeks ago "Excelsior" asked a> question (1027) to which I have uot yet seen any reply. lie requested an explanation of the working of the cone, sun, and planet wheels, and reversing motion in Higpdns' roving frame.

1 presume " Excelsior '* is sufficiently well acquainted with the roving frame to know thai the spindle twists the fibres of cotton together as they are delivered in a band from the draught rollers, that after being twisted the roving passes down one of tlie legs of the flyer and is wound in a spiral manuer round the bobbiu In layers until tho bobbin is full.' The bobbin and spindle both revolvo in the same direction, and if they both ran at one speed, "Excelsior" will readily stc that there would be no winding on of the roving. To wind on the roving as it is delivered from the rollers wu must either run the bobbiu quicker than the spindle, or run it slower; or, as we say, the bobbin must either lead tho flyer or the flyer must lead the bobbin. Whether bobbin or flyer leads Is immaterial to the description ; the fame mechanism is used for each, the arrangement only being different. We will take the case of the bobbin leading the flyer.

The delivery roller aud spindle revolve at speeds which havuatixed proportion to each other, the bobbin revolves at varying speeds because of its varying diameter. As the diameter Increases the speed decreases, so that its speed is always equal to the speed of the spindle plus a proportionate speed of the rollers, which additional speed will, of course, be as their diameters are to each other.

For example, suppose the spindle to make 10 revolutions for the roller's 1, aud the diameter of bobbiu equal to tho diameter of roller, the bobbin in that case must make 11 revolutions for the roller's 1; if the diameter of bobbin be Increased to twice the diameter of roller, tbo speed of tho bobbin is reduced to 10\} revolutions for 1 of roller, and so on for any other diameter of bobbin. To regulate this varying speed of the bobbin is the office o' tho coae drums and differential pulleys, or, as "Excelsior " calls them, sun and planet wheels. Besides revolving round their axes the bobbins have an up and down motion given to them by the reversing bevels, by which meant the roving is inudo to traverse from end to end of tlu* bobbiu, aud is wouud in a spiral niauner rouud the barrel; this up and down motion is called the Cop^'- 'T

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motion. When one bevel, in gear with the pinion, has driven the bobbins to the top, it is immediately thrown out of gear with (he pinion; the other bevel coming; into gear at the same time, reverses the motion and causee the bobbins to descend, and so on for each layer of roving as the bobbin fille; the speed of this up and down motion of the bobbin also decreases as the bobbin increases in diameter.

The following rough sketch of the arrangement In Higglns* roving frame will render the matter more intelligible, and enable the motions ef the several porta to be traced out.

P T is the driving shaft, the driving pulleys at Г are turned by a strap off engine shaft; spur wheel s keyed on same shaft drives the spindle shaft; spur keyed on end of shaft at T drives top cone drum shaft, "ii the other end of which is a wheel that driree the draught rollers.

It will thus be seen that in the speeds of the spindle and roller there is no variation! The bevel a is keyed on the driving shaft, the bevel 6 am! the spar e, which are connected together, run loose on the driving shaft and drive the bobbin ehaft. Communication between the wheels b and a is by mean* of the two bevels с e, which revolve on studs fixed in the wheel D; the wheel D also.revolves loose on the driving shaft and curries the bevels с e romM with it.

If the wheel D were a fixture, the wheel Ъ would revolve at the same speed as the wheel «, there would be no variation in the speed of the bobbiu, and being geared like thespindle, It would ruu at the same speed as -ci n-ili\ consequently there would have been no wlndiug on of the roving, but the wljeel D being allowed to run loose on the shaft and receive motion from the cone drums, its speed is regulated by them and commnntcated to the bobbins.

The top cone drum receives its motion from the end of driving shaft, as mentioned above; this is communicated by means of the strap to the bottom cone drum, and thence to the differential wheel D, which in this case revolves in the same direction as the wheel a« to whoee speed it adds its own, thus causing the wheel h to revolve quicker than the wheel a,- consequently the bobbin runs faster than the spindle, and winds on the roving as delivered from the rollers.

The cone drums arc set out so that they will give speeds corresponding to the different diameters of the bobbin ; at each increase in the bobbin's diameter the strap is shifted by a rack the required distance on the drums, the bottom drum is driven slower, and, consequently, the wheel D, which» adding less than before to the speed given out by the wheel a, reduces the speed of the bobbin as required.

The reversing bevels, also receiving their motion through the cone drums, are also driven slower, the speed of traverse of bobbin being reduced accordingly.

To " Excelsior's" second inquiry, the best books on the subject are Dr. Ure's "Cotton Manufacture of Groat Britaiu," and Montgomery's "Cotton Spinning," both of which were old ; no doubt there are new editions embracing recent improvements in machine*. Works of this description he would get by applying to Thompson, bookseller, Market-street, Manchester. B. W. Jt.

QUESTIONS FOR MILLERS. Sir,—Thomas Evsne, page O'J. quotee my words, *' the long spindle will make the stone haug steadier." I certainly should not recommend a spindle I5in. long, for of course If it hangs steadier it will hang more tdngaish. Near the centre of gravity is the proper place for the bearing, but I much prefer the crossbar to the universal irons; we tried two or three sets many years since, but fouud them inferior to the crossbar. A more practical letter than that of Thos. Evans I have seldom seeii,aud any oue following his ndvice will not be far out, although doctors will differ. 1 think we millers have hadaliou's share of the Jskgr.isii Mechanic. I want to see that most Important trad« " Bakers and baktu »" fairly represented. 1 consider they have been left out in the cold much too ioug. I beg to say in my bakc-office the heats of all the liquors were taken with as much care as they are Id a brewhouse, and the result was a first-class trade.

K. N. Smith.

THE ORGAN AND ITS CONSTRUCTION,—No. 18.

Вт An Adept.

Sir,—In continuation of the division of our subject which was treated of in the last communication, on page 538, No. 955, we next come to a form of pipe in winch the four sides, instead of being straight, as in these previously described, are formed in the manner represented In Fte.74, which I* a front elevation of the pipe complete; it is to be understood that both front and back are curved in в. similar manner to the sides. No i lint the internal mensures are —at the Upper surface

of the block, lin. by Hin. (being the same as the other experimental pipes), and in the middle at the largest part '-'in. by 3in. Some special arrangements are requisite for its manufacture, which must be next described, as otherwise it will bo found extremely difficult to construct. Kef erring to the instructions given on page 410, No. 260, it can be readily understood that the block being cut of the necessary taper, the upper ends of the sides after the first gluing will diverge Into ¡» V form; these, after being perfectly dry, are to be treated as represented in Fig. 75, which almost explains itself—the stretcher Л it must be remarked is not made'.fn one piece, but of three or four narrow strips, us otherwise It cannot be got out at the top of the pipe after the whole is finished. The means of keeping the upper extremities of the sides in position is shown at B, bemg simply a piece of } stuff with a notch of suitable form cut into It sidewnys to the course of the grain, which forms a good and strong clip or temporary fastening with very little trouble. When thus secured into the proper form, the edges are to be planed over, which, from their curved lorm. Is a somewhat delicate operation, and the second and thirdgluinga proceeded with in the ordinary manner as before described; only from the wood forming the front and back of the pipe requiring to be forcibly bent Into shape, similar wood clips to that just described are to be used to the number of six or eight along each side, thereby affording a very neat and ready means of retaining the work until the glue Is thoroughly hardened; also it will be well to put a slender jin. screw into both upper and lower extremities at each angle as an additional security.

The next peculiarity to be noted is the circumstance that in the forms of pipe prevlou sly described the passage for the wind was constructed by bevelling either the inner side of the cap or the front of the block, the opposing eurface in either case being simply a plane, but iu this description of pipe both cap and

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the description given will be found sufficiently explicit, the greater part having been written during severe bodily suffering.

SLOT-CUTTING REMARKS.

Sir.—I wish "F.R.C.S.," 24.19, had sent copy of the question to which he wants an answer. I have only taken the English Mechanic during the past nine months, and if I had the back numbers could hardly be expected to search for it. I should think a modification of tha

block are bevelled, as shown in the section Flg. 70, the Internal appearance of the cap being represented in Fig. 77. This system of construction is remarkable for the great sonorosity it produces; the pipe itself now betöre the writer, if etruck with the finger nail, emitting a sound resembling that produced by thebody of a violin nndcr similar treatment, aud the note when sounding bein£ of a singularly penetrating character. It will also Incidentally afford a useful lesson on another point-viz, that from the Internal area being increased in the manner described, the resulting note will be found to be considerably lower in the scale than that produced by a pipe of equal length and with a similar-sized block but straight sides.

Note.—I consider this one of the most interesting —albeit undoubtedly one of the most troublesome— forms of construction. I can well remember my own first attempt at making a pipe upon the plan, before I knew how to go to work, and even using the method I have described, it will take three or four times the ordinary amount of time and care, but it is nevertheless well worth using where space and labour are of no consequence. The peculiar character and intensity of the note well repnys the additional trouble. I trust

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drill used in Shanks's machine for slotting metals wool«! suit, provided a moderate depth only is removed at a time, and the following will describe it with assistance of the sketch Fig. 1. The rod prepared for the drill hat». Ing been flattened on both sides till only about one-third of diameter remains in the middle, a broad diagonal notch, a b с d,lñ cut with a file, and the faces a /, с e tiled away to clear, and leave keen-cutting edges at a and c. This tool ehonld take a cut as deep as the diagonal notch itself, which might he a great deal deeper than I have shown In the sketch, for economy of space; and for incut I the extreme corners of the cutting angles should be ground off. Such a tool works capitally in iron, brass, or steel; but for them is not filed away at f a, e л The tool may be made as shown by the curved dotted lines, as the corners are, of course, too keen for leaving the bottom of the slot smooth, and tho feed must be given during the travel of the tool backwards and forward«, and nut at the ends of the slot, unless a hole Ьаа been bored there first to Btart the tool into. Both these objections are got over by the use of a half-rouad bit. Fig. '2, relieved round the back, as shown, so as to make the cutting edge prominent, and running in the direction indicated by the arrow, and 1 believe this would be found the best tool possible, or nearly eo. À friend wbo пая had great practico says a half-round bit is better for drilling boles than any American twisted drill, uni I have frequently used them for drilling out of the solid metal such things A* rifle-barrels as much as 33 inches Jong.

J. K. P.

EXPLANATORY

Sir,—I must beg those of your readers who have asked questions of me not to look on my silence aa discourteous. 1 am, as you are aware, over-preese4 with work in connection with my atlas and other matters, besides the necessary collection of materials for a lecture I have engaged to give at the Royal Institution on May 6th. 1 do not like to answer questions unless 1 have full time to consider them iu all their bearings, and juat now this is not the case.

I salute " F.R.A.S," and sheathe my sword also. Every line he writes telle Dm шы he will be the last to misinteipret my anxiety to see in scieutitic questions the exact facts stated, where possible. When mp turn comea I shall be ready to welcome cheerfully his criticisms on whatever error 1 may make.

I am glad to see he has " screwed up'' " Veritas." whose numerals were a nuisance. If ■' Veritas"* would only c*rry his ligures to tbe locate commonly assigned to Truth, we should all be ready to obey the old proverb and "let well alone.' JUCIUKD А. РвОСТОЛ

MR. BEARDSLEY'S DYNAMICS.

Sib,—As I read through Mr. B.'s letter, I rejoiced, saying to myseir ** How lucky that it requires Do answer, being ьо clearly written by one who does not even know the fundamental laws of dynamics." But. alas! there was that in the letter which required reply. So long as Mr . B.'s ignorance of dynamics only makes him try to stop »he earth's rotation, all is well; but when it leads him to teach people how to jump out of a train or carriage in motion, it may be apt to do mischief. Let me beseech Mr. В., if he ever should have occasion to jump out of а carriage in motion, not to leap the way it is going; but. the other way. If possible let him jump with all his force from the back of the carriage, lie will find that eveu if he fall (which is likely) tho fall will not bo hevere (he might add the precaution of letting his head come fir^t to the ground); eu tbe other hand, by jumping the way the carriage i« moving he will add to the violence of the fail.

It would be a waste of time to touch on his reasoning (save the mark!) about the earth's atmosphere. Galileo laughed away euch puerile objections two centuries and* holt ago. H A. Pkoctok.

MATERIALS FOR PAPER.—A II INT TO COBNISHMEN.

Sir,—ЛУШ you allow meto call attention inyourfarreaehiug journal to a little matter which maybe of impor*. anee to many people?

There la at present a great demand for materials for nuiking paper, so much so that paper-makers have decided to increase the price of paper ten per cent. I remember some years eince, while walking over the immense sand banks betweeu Hayle and Porto Towan, Cornwall, seeing large quantifie« of tall rushes when

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