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THE LUNAR CRATER PLTJTO. Sib —The results of observation of the floor of the lunar'crater Pinto which have appeared elsewhere see Slud,*t. April, 187", p. 101 belugof Interest in connection with questions now agitated relative to changes on the moon's surface, the following sunimaiy of further observations during the April lunation may not be uninteresting to your numerous readers

The observations were made by Mr. Gledhill; ol Jir. Crowley s Observatory, Halifax; Mr. Pratt, of Bricbton, and Mr. Elgcr, of Bedford. Sixteen only of the 35 known spots were seer.; they are numbered 1, 1. 4, 5 6 9 II 14.10,17, 22, 24, 25. 30, 32, and S3, but Mr. Gledhill detected an unrecorded one, which is numbered 35. Of these the following were seen by the three observers-vii., Nos. 1, 3, 4,5, 16, audi, ; no

doubt*, therefore, can be cast on their visibility duriue April. No. 14 was observed by Messrs. Elgcrnud Pratt ou seven occasions, but missed by Mr.Gledhill Ibo spots seen by Mr. Gledhill only were Boa. 0,0.11, W. 32 SB and 35; by Mr. Elgor only, Nos 24 and 2.), and by Sir. Pratt only, No. 22, Taking spot No. 1 (the most constantly seen) as the standard = l'OOi, the degrees

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of visibility are as under
Spot 1 4 3 17

Vis. 1-000 1000 -895 -780
Spot SO 8 11 24

"Vis. -210 '105 -105 -105

The number of observations of tho spots between April, 1800, and March, 1870, inclusive, amounted to 771 in 108 series ; those during April amounted to 118 in 19series. These numbers give" for the avornge number of spots visible on any one evening. The curves of visibility of 14 spots have been projected for the 121unations ending March, 1870, and of these 14 spots S were not seen on any one of the 19 sets of observations— viz., Nos. 2, 7. 10,13, and 19.

The intermittent character of the above unrecorded spots in April Is beconiiug more and more manifest. No. 2 has been observed 7 times only between Aunist, 1861, and March, 1S70, inclusive. No. 7invislblcin June and July 1869, and in February, March and April, 1S70. No. 10 invisible between Oct, 1SC9 and January, 1S70. inclusive. No. 13 seen on 28 occasions during the past year, invisible in April, 1870. The same may be snld of No. 19, it having been seen 27 limes during the last year, and invisible In April, 1870. No. 22 may be included in the same class, for although It was recorded on every line evening iu August and September. 1869, it Is now but rarely seen. The variationsln the visibility of the spots more constantly seen lead to the same conclusion—viz., that their visibility is also intermittent. Itmust, however, be borne in mind that the visibility of Bpots very rarely seen, once or twice for example, in the course of a lunation, may depend upon the slate of the earth's atmosphere; it is, nevertheless, difficult to conceivethat the earth's atmosphere is capable of obscuring spots for months together, while others quite us difficult of perception are visible.

An Increased accuracy is attainable by the number of observers being augmented, for, as iu all observation of the kind, eirors that necessarily affect the lew are eliminated iu tho case of the greater number, so errors arising in the visibility of the spots from differences in the state of the earth's atmosphere at distant stations, and also iu cousequence of the overlooking of minute objects by one observer which are distinctly visible to auother, disappear to a great extent, when the observers are numerous, the greater weight being accorded to the visibility of those spots that are seen bv the greatest number of observers. W. It. Birt, Cynthia Villa, Walthamstow.


Sir,—Amongst the requirements for life boat service. It has been held to be a desideratum to And means for depositing an anchor on emergencies at a distance from the chore convenient for using a block and double rope attached thereto, to enable those on shore to haul off a boat through surf, and to the various schemes for this purpose, I wish to offer an additional one. There is a certain fishing implement of the pot hunting or poaching class, by which a line can be carried out (with hooks, &c.) called an "Otter." the construction and action being this: A flat board Is (by being weighted with lead) made to swim edgeways; to It Is attached a loop similar to the bollyband of a boy's kite; to the loop is fastened the fishing line in a certain position upon launching and paying out the line. The " Otter" leaves tho shore in an oblique direction, and is hauled along to the extent of the Hue. On this principle it is proposed to construct a machine of the following description. Fig. 1, A IS O is an anchor, of which the ring is at A, and single flake BO attached to aflat frame built up of board and cork. A B I>C, the upper portion of which, C E V 1>. is removeable, sliding out from the lower portion backwards, having line and ring fastened to it L E, the whole ol such buoyauey as to float the entire machine level atabout the line E F; G K H loop or bollyband, to which, in proper position for effecting the o"blique motion in hauling off, are fastened a block and double line rove there through I K. A stronger connection is to be made between the block K and anchor ring A, by line or rope A It. In use, the upper sliding portion of the frame is to be fastened by a line Jrd the strength of the line L E, also the bollyband is to be so contrived that the sliding out ol the'upper part of the frame shall let it fall loose. The action Is presumed to be this (i.r., supposing this saltwater "otter" behaves equally well with its fresh water progenitor, aud there seems no reason to suppose it otherwise), that upon launching, the machine drawn by double rope It I, will proceed to sea, and gain oiling according to length of rope K 1, trailing behind It the line L K. On acquiring proper oiling and position, the travelling line is to be jerked so as to break the fastening Jrd its strength, aud pull out the upper sliding portion of the trams, which is to be hauled ashore, and also

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direction required, and, finally, the double rope bo in position to be efficiently used for hauling off .the life boat. Fig. 2 shows a sketch or the position of the "Otter" floating, seen from above. A B shore line. L E trailing line, by pulling which the upper frnme is drawn away. It 1 double rope to shore. The machine to be fitted on a Bmall carriage with long polo aud launching ropes, as in life boat carriages. Two wheels only are wanted lor carriage. The whole affair might weigh from 4cwt. to 6cwt., including carriage. Suffolk Amateur.

. P.S.—I may just add an idea about self-righting life boats. The principle is as old at least as any grown man who, as a s mall boy, put a leaden keel to his play boat, and deduced from the observation that the form of the upper works has nothing to do with the matter, but that it depends altogether upon the centre of gravity or otherwise on weight below overbalancing weight above.


Sir,—1 enclose you the only one I have left of these ancient stone discs, trusting you, or some of your correspondents, may be able to throw some light as to the purpose for which so much trouble has been bestowed on them ; they are only found iu one field on the farm, but were much more plentiful forty yearn ago than now; at that time, we used to suppose they had been made by children, as wheels for toy carts. One of my ploughboys, about this time last year, picked up about a dozen of them; ho brought four or five home, throwing the others away. The one I forward is much the smallest, aud the thickest. I am sorry to Bay the others are all lost; the one I Bend is much more carefully made than any of the others were. Noue of them were the same size ©r thickness; some of them showed the Baw marks very distinctly; they had been Bawu out of cylinders of different sizes; the


holes through have been bored after each disc was cut off, sorne of them quite oblique, but all rimmed from inch side as this is; they were all thick in the middle, -hough none were so much rounded off as the one Bide of this, neither had any of them the perfectly flat side you see in this one. I do not kuow of any stone iu this neighbourhood that at all resembles this they are made of. I recollect scciug them with serrated edges, ae though the notches had been cut with a flle; I also believe I saw some of the same dug up at Uriconium (Uttoxeter), about two miles from here. From the careless manner with which the holes were drilled through them, I sho'.il! say it has been for the purpose of threading them on a string; the one I send has evidently lain in the grouud very many years, by tho gravel being so (irmly attached to it. The opinion of some of your readers' on it will oblige.

I have seen some quite twice as large, aud above ball as thick. . A Subscriber.


Sir,—Allhough I am no chemist, and am therefore unprepared to account for some of the failures which may happen in the above art, my own repeated failures have, nevertheless, taught me a few lesBous, and have led me to the opinion that nine cases out of ten of these failures occur chiefly through want ol sufficient care in cleaning the glass surface intended to be silvered; and although the few hints I have to offer do not perhaps apply entire to the " Rochelle salt " process, your correspondents, M. Gray, p. 163,and " Interested." p. 191, may, I hope, find them useful as regards the washing. . .

The following particulars as to chemicals refer to

Liebig's process as given by Browning, this being the only process I have attempted. The proper cleansiug of the glass is doubtless equally ns necessary in both processes. In the first place, distilled waler, that is, chemically pure, must be used, I have'not tried rain water, but should think it would succeed when collected in clean vessels and properly subsided. 2nd. TbechemicalB shonld,beobtained of areliablechcmlst nitrate of silver is, 1 bclicvo, ordinarily good. The potash must be pure by alcohol. The ammonia should be the strongest obtainable. In cleaning the glass, the strougest nitric acid should be used ; If good;it gives out copious fumes, and may be easily known by the prompt manner in which it attacks the eyes and nose. First place the mirror face upwards (previously cemented to the wooden block) in a large dish, pour the nitric acid on it, and gently rub the glass all over its surface and Bides with a pad of medicated wool plugged into a glass tube; then rinse the wool in common water, and repeatedly wash off the excess of acid, taking care to give the same attention to the sides ;as to the surface; this done, do not touch the glass with the fingers, but take hold of the block to which it is attached, and hold it under ruuningwater from a tap for about five minutes, continually moving It, that the jet may play freely over the back, the sides, and lastly tho surface; then examine the surface of the glass, aud if the water baa a tendency to run away from the edge of the disc, as If greasy, the process must be repated until all greasiuess disappears. The glass is then laid iu a sloping position, and another woollen brush used to cleanse it with distilled water; this brush should not be touched with anything but distilled water, into which it is now dipped, and the glass repeatedly rinsed all over with it, until any apparent greasiuess which the first contact with distilled water may occasion entirely disappears.

The glass is now ready for silvering, and is laid wet, face downwards, Iu a dish containing a little pure alcohol (just sufficient to touch tho entire face of the glass) until the silvering bath is quite ready. Caution must be observed throughout the entire process not to touch the face of tho glass once with the Angers if possible. One or two particulars as to tho silvering fluid may be serviceable. II the process la conducted in cold weather, It is advisable to warm the solution slightly, this may bo done when tho distilled water is added, by warming somoof it in a clean cup placid in a basiu of hot water for a few minutes; this helps to subside the precipitale more quickly, and renders tho fluid transparent before pouring into UiesilveringdiBh, which Is necessary to prevent spots in the silver film. Another essential item is to completely dissolve the milk sugar; this caii scarcely be doue in cold water, but is quickly done by warming in a cup placed in hot waler. as before. Tho slight warmth given to the silvering fluid has also the important advantage of giving a harder and more adhesive film.

In placing the mirror face downwards in the bath, care sho.ild be taken to enclose no bubbles under Its surface ; one side should be lowered first, and then the entire surface brought gradually level; it should not sink too deep into rhe fluid ; the nearer the surface the better, providing the face is fairly immersed. When the film iB complete, it Is removed and immediately washed under the tap for five minutes as before, then stand the mirror on edge In a dish, and gently rinse with distilled water either with the woollen brush or with a piece of soft clean sponge ; when it is thoroughly dry, polish first with clean wash leather, then with rouged leather.

In answer to Mr. Gray's query, tho proper aperture of a diagonal plane fora Newtonian may becstimatod

at Jib. or -th tho aperture of the speculum, whatever

its size, providing the focus of speculum is thrown just outside the great tube, as is usual. ,„„.„„

As the" Harmonious Blacksmith "and "F.RA..S. have associated my name with tho subject of "pls"nlBcd mirrors," I mustadmitmy entlreignornnceof the process, and as to the advantago of platina over silver in point of reflecting power, I should have serious doubts, and as to the "baking process" for such sensitive thloesas specula I should have very little doubt, and should require positive evidence to convince me that it could be anything else than a failure. W Purkiss, 9, Cumberland-street, ltomau-rond, N.

EXPANDING DRILLS FOR MINING PURPOSES. Sir —In the issue of the English Mechanic of the Oth inst., 1 find you have inserted a short paragraph (taken from the Minim/ Journal) relating to au invention by Mr. E. P. Gleason, of an expanding drill for boring purposes, by means of which a chamber or cavity can be made at the bottom of a drilled hole for the reception of the blasting powder, and by which means a vast additional force can bo obtained for disintegrating and blowing up the rock. Now, It so happens that I myself iuvouted a similar drill borer about seven years ago, a description of which, at the time, appeared in the North Wales Chronicle, which was extracted the next week after its appearanco in the columns of the Mining Journal. Judging from it In the note In question, it would appear that Mr Gleasou's invention and my own are precisely similar in principle, and pretty nearly so in the carryin" out of it iu detail, which certainly is a somewhat strange coincidence. In my Invention, the cutting part is composed of two cast steel blades, which are inserted about 4in. above the bottom of the irou rod, the blades being screwed in so as to be the more easily taken out or replaced when they require sharpening. The chamber at the bottom, has a diameter of sjin. (the hole made by the common borer being ljin. iu diam ), and as the perpendicular hole is coutiuued bv the operation 4in. or 5ln. below the chamber, the latter can te extended to any reasonable depth. My expanding drill-borer has beeu successfully tested In several slate quarries in the neighbourhood, and notably so nt the Hcndre Ddu slate quarry, near this town. Sir Edward Poore was at that time the managing director of the said quarry, and was assisted X>y Mr. W. Jones, a thoroughly practical miner. VVo experimented on a largo piece of rock, and a holo was drilled to the depth of 11+ft. The charge was 101b. of rock powder, and above 500 tons of rock were idown up, the explosion being н tremendous one, and hu rook was shattered in all directions. This result vas considered to be most satisfactory by nil vrho теге present and witnessed it, as the quantity oí slate ■nek obtained by the powder charge of 101b. was >nual to what was usually obtained in the quarry by ;he expenditure ol loulb., to say nothing of ithe great »xpense saved In the matter of labour. I rom this you will perceive that Mr. Glcnson's invention has been long since anticipated by myself, lu an obscure town In North Wales. Ab a contributor to your valuable paper for the last four years, 1 trust you will do me the justice to admit this letter iu the next number of the English Mechanic.

John Williams (Joan Madoc), ehlpimjth, Tort Madoc, Carnarvonshire,

"С В. O., HANTS," ON SEVERAL MATTERS. Sib,—" Salopian," on page Ш), wishes to know how ¡t is that the circumference of the earth at the Equator Is greater than the circumference drawn through Iho poles i be quotes the difference at 25 miles. A moment's reflection will show him what a mere trine this Is when we take into consideration the vast dimensions of our globe; I question very much if many billiard balls-perfect ns they apparently arecan boast such a slight departure from the form of a true sphere. I believe myself that centrifugal force certainly causes what "Salopian" refers to, and that its power, exerted throughout the whole mass of the revolving earth, is just so much, and no more than sufficient"to occasion this swelling out at the Equator. This opinion will, I think, in no way stultify the arguments in my previous letter on the earth's rotntion.

Touching this same subject, I must confess that It was with the greatest possible gratification I read Mr. Proctor's kindly-worded comment on my letter; encouragement from that gentleman is worth something. Will he allow me, in my turn, to present my compliments to him, and trust we mny often have the pleasure of reading his most vnluable contributions to our Mechanic? .... , .v . T

An apology is due to " An Adept," inasmuch that I bave delayed so long acknowledging his kindness in replying to my question on the construction of Dourdon pipes. The fact is, |I have been waiting, unwilling to bother him during his unfortunately still continued indisposition, but seeing that other correspondents are not so consideróte, and fearing that he may perhaps deem me ungrateful, which I assure him is very far from the case, 1 can hold out no longer. The plan that gentleman suggested—viz., to place the pipes in two rows, would have been obvious to me, had the special circumstances of my case admitted of it; I worded my letter badly, and ,! An Adept " naturally thinks depth is no object. What I wish to ascertain is, could a pretty good quality of tone be obtained from pipes constructed with a much greater depth than usual in proportion to their width ? Tor lnstauco, could CCC be made 4jin. by Sin. internal measurement? The double row plan I wish to avoid If possible, for many reasons. I trust our correspondent may soon be restored to perfect health.

What In Iho name of all that is polite nndcharitaUe, can "Eleve "—himself, 1 presume, a musical manmean by putting such a question as this to your correspondents? '• Tell me why a double manual instrument should be preferred to a single, if the single eet of keys can be made to do tho work ae well?" Is this from Lord Dundreary, or what t One might just a» eenslbly put the query, why eat bread and butter when bread alone could probably do its work just as well In nourishing the animal system? Amateurs, and intending purchasers, make no mistake, you will get incalculably more real and lasting satisfaction from a double manual than a single; ask any organist. Chorus and fugue playing may be performed very well on a single manual, but how about " He was despised, from tbe "Messiah," or, "O, rest in the Lord," from "Elijah," and tho hundred and one other pieces depending for their very life and soul on a clear, distinct, and individual melody? To my mind the harmonium, especially, requires two manuals, from the very nature of Its tone, whoso most marked characteristics are, in a good instrument, an apt capability for producing grand and majestic harmonics, but there always seems to bo a falling off when anything of a melodic character Is attempted, hence the value of two rows of keys. I on my side appeal to the " llar- i monlous Blacksmith" for his verdict; his writings, which every ono must enjoy, speak well for the value of any opinion ho may offer.

The subject of harmoniums naturally associates itself with Mr. Hermann Smith, and If you, Sir, have been instrumental in bringing him back among us, you have my moet cordial thanks. Let any one peruse Mr. Smith's chapters on tho harmonium, from their commencement, and seo what ground he has broken up, before untrodden, and what vistas of thought, apart from the mere dry details of construction^ has opened out to a thinking mind. A painstaking and conscientious writer, Sir, and a comrade wo cannot afford to lose from our ranks.

1 am delighted to see such a long list of extracts from various correspondents relative to the success of our paper. You merit our very warmest praise and congratulation. There can bo no doubt that to your own able and talented leadership all tlio increasing excellence of this periodical is due; you have indeed reason to be proud. Sir, of your achievement, for the press has certainly never before sent, through the "length and breadth of the land, such a mass of useful lietcrature at such a nominal price-no, nor at any price. My beet wishes are yours. C. R- O.

tool buried in the clean metal under it ; but some castings are so uncommonly hard that no tool will touch them, especially those cast in the country, and it is impossible to do'anything with them. If 'Amateur Turner " will tell mo tho diameter of his work, I shall be able to inform him how many revolution* the mandrel shoufd mako In ono miuule to give the proper cutting speed.

As to the eecond part of the question; a cylinder may be bored very fairly by setting it up on tho faceplate of the lathe, if a large one (a small one may be soldered on to a brass chuck or held in the cup chuck) by ono flange, and running an iuside tool through it by means of the upper slide of the rest, taking care to get the slide set perfectly parallel to the axis of the mandrel, and frequent use of the callipers is the only means ef ascertaining this, liut there is another plan which I think Is superior to tlie above itf " Amateur Turner" Is the happy possessore! n screw cutting lathe), and that is to set up the cylinder to be bored on the saddle of tbe slide rest (the rest Itself removed) and fixing a cutter bar with protecting cutter between the centres of the lathe and causinz it Che cutter) to traverso through the cylinder by tho sliding of the saddle ; this, if properly managed cannot fail to produce a truly cylindrical bore. Cylinder covers arc turned by chucking them in a wood chuck, and turning one sido and edge, then reverso them to turn the other stde. And now, having answered the above questions, allow me to ask of my fellow-readers— viz., What Is tho construction of Ho;tzapflW's screw cutting tool-holder or cutter bar for V or square thread«, by which the tool may be adjusted to the exact rake ot the thread. A drawing to scale would oblige. G. W. A.

piece would have with any given O. G.? An ex ample wmild greatly oblige. 5th. How are the webs in n transit eyepiece protected? 6th. What is tbe plan of the pancrntic eyepiece? I have often beard ol it, but never saw one. rth. Is Kepler's third law exact? 8th. Would not " F.R.A.S." describe a spectroscope more minutely than he did in No. '¿or ? 1 am sure it would be interesting to a great many of us, especially now a» be is going to tell us something of it« uses. 9th. What is tho size of the Cambridge (U.S.) refractor, and also the Melbourne Telescope? ScoBrio.

P.S. How ceuld I Und the focal length of a small concave lens.

Sin,—The readers of the English Mechanic have
reccntiv been entertained with a rather acrimonious
discussion on tho subject of the colour of the bolts of
Jupiter by two of its most valued contributors. In
one of the letters I perceive that one of tho disputants
admits that an eye "successful In detecting minute
forms of detail may altogether fail to notice grada-
tions of colour."

This fact has been considerably enlarged upon by "Omicron" in the series of articles ou Colour-blindness, an<l it appears to me that there is clear evidence in the columns of the Mechanic of a caso of colourblindness, although there is not, purhups, sufficient evidence to determine which one of your correspondents is affected with abnormal vision.

Mr. Browning says of tho drawing of Jupiter that appeared in tho Student that " the yellow and red are too bright, and the ashy blue or gray far too dark." Mr. Denning says that the colour of Jupitor, as seen In his telescope, was very apparent, but not so dark as shown in the print. Mr. Giover says that the colours in the drawing are certainly too vivid. In opposition to these remarks, Mr. 1'urklss holds the opinion that Jupiter appeared even moro vivid than the engraving in tbe StiuleiU. Perhaps these conflicting remarks are hnrdlv sufficient to warrant tho charge of colourblindness, as "Omicron" has employed tho expression, for tho discrepancy in tho description is ono rather of quantity than quality, liut us the term nppears to be applied to ev cry degree of deficiency of appreciation of colour, I have adopted it here.

Since throe observers are inclined to one opinion, and one only holds the contrary, I should bo Inclined to suspect some anomalous vision to have vitiated Mr. Purkiss's observation; and the object of tlio present communication is to ask your readers whether an abnormal vision, manifested in any considerable degree, as in some of the cases specified by " omicron." would be likely to produce telescopes in which chromatic aberration would not be duly corrected. It appears to me that if tho corrccUou can bj computed by mathematical formula-, it is not likely to ptuduce any ill effect; but if tlie correction bu determined by continued examination of tho image of an object, and continual grinding, till tho object is seen to ".he satisfaction of tho observer, depending upon uo fixed law. but left to the option ol tho observer, the questlou is one of some importance.

It Is needless for mo to say that I am ignorant of tho method employed by makers for correcting the chromatic nberratlon of telescopes ; and if it is no', asking Mr. Purkiss to reveal the secret« of his guild. I should be glad if he would give mo some information, especially аз regards refractors. Columbus.

THE TELESCOPE. Sir,—Many thanks to "F.R.A.S," for his kind answers to my last queries. The reason 1 asked would he think a3in. telescope good, was because I saw among the testimonials to Solomon's 65 telescope, the following from the Rev. Г. K. Winslow, " lu Mr. Proctor's book on the Telescope. I fiud the following passage about tho trapezium. 'The trapezium affords a useful test for the light-gathering power of the telescope. Large instruments exhibit nine stars; but our observer may be well satisfied with his instrument and his eyesight if he can see five with 3J-inch aperture: a good 3ln. glass shows four distinctly, but with smaller apertures only three are visible, and in a note he adds, ■ I have neverbeeu able to see more than four with 35in. aperture." Now with the telescope I obtained from you last year, I can see five stars in the trapezium." All Solomon's £r> telescopes ate warranted to show five „tars in the trnpeziumö Orlouis. It was In pagclll of the current volume,that " F.R.A.S." said, iu answer to "A Poor Lad," " A 2Jln. object glass could not possibly divorce anything closer than a pair of stare Г-5 apart ;" however, " F.R.A.9." may not have moaut a 0 mag. pair. And now, Sir. I nmst with your permission, trespass on " F.R.A.S.' s '■ kindness a little more. Would he be so kind as to answer the following queries :—bt. Where can I obtain tho "Nautical Almanac," and whnt is Its price? 2nd. What moderately cheap hook gives the best list of U.A. and declinations': :'.rd. Is there any cs-ential difference in the mounting of reflectors -uid refractors? That is would It not do to take a 'lei for a small refractor

..-,■....,, ■-. from an Equatoreal reflect*,.. 4th How can I calcu

■o ns to "et underneath the scale, and tbe p-riat of tbe ' late the field of view that any given Iluygbeuian cye


Sir,—On page IS«, Query 37"1, a question is nsked relative to turning, which, with your permission, I will answer. , _ ,

I imagine the cause of " Amateur Turner s failure is the speed at which he drives his work, as no tool will stand even against soft wood, if it is driven at too great a rate. The best way that I find to take the •cale offcast iron is take a moderately deep cut at first,


Sir,—With reference to tbe letter signed " W. R.' in your issue for .May 13, page IS?, there are or rather were four modes of estimating the organic matter in water Firstly, the original old method of treating the solid residue obtained by evaporating the water to dryness, nndestiinating the loss, which was ascribed to "organic matter." This is now quito abandoned as being uusatisfactory and altogether erroneous. Secondly, there is the system of estimating tbo organic matter" by means of an acid solution of permanganate of potash, as detailed by Prof. Miller in his paper entitled "Observations on Somo Points in the Analyses of Potable Water*,"tn tbo "Journal of theChemlcalSociety," 18(15, Vol.XVIII. This,however, has beeu proved to oe quite unreliable, besides being unsatisfactory at the best. In fact, Prof. Frankland's comment on it, "totally untrustworthy," has been thoroughly well sustained by succeeding trials with it.

The third system is that of Messrs. Wanklyn, Ch«pman and3Iiles Smith, and isdetailedat length in their paper on "Water Analyses," read before the Chemical Society on the tíüth of June, 18i>?. This systom which was criticised by Mr. Dugald Campbell (" Laboratory," Vol. I.,) and again verified and slightly amended by Prof. Wanklyn In his " Verification of Messrs. Wanklyn. Chapman and Mnltb'sMethod of Water Analyses" i n the 'Journal of the ChemicalSoclety," new series. Vol V., p. .Vil, disputes with Professor Franklaud's method the claim for pre-eminence.

The fourth system is that of " Frankland aud Armstrong," the principle of which is detailed by Mr. Davis on page !-Г of the English: Mechanic. This system Is based ou a gasometric estimation of tbe organic nitrogen and carbon, and theoretically is the finest and most accurate of the four. Professor Frankland's paper iu the "Journal of the Chemical Society" violently attacks the method of Messrs. Wanklyn, Chapman and Smith, and in it the author attempts to demonstrate tho thorough unreliability of their system by means of a systematic series of analyses, comparing the results obtained by his use of Messrs. Wanklyn's, &c. method, with the results furnished by his aud Arimtronij's process, and putting down the former as wrong on account i.f tho difference between the former and the later, which is assumed to be correct.

Prof. Wanklyu retaliated, and in the "Journal of tho Chemical Society," Vol. XX., attempts to prove tho unreliable character iu practice of Krankland and Armstrong's method of gasometric analysis, und vigorously defends his own system. He also shows by reference to Mr. Miles Smith's paper in the "Laboratory," Vol. I., p. 114, the danger and liability to error of tinyresult based ou theaualyses of tlie residue obtained by evaporating to drvntss a large quautity of water. Since then the discussion and rivalry between ihu two methods has waxed hot, Professors Wanklyn. Schenk, and Chapman having improved tbclr posltiouby their masterly analysis of the " Action of Limited Oxydlsation on Nitro and Nitrogenous Organic Bodies," and of the action of nlkallue permanganate of potass on organic bodies. Professor Frankland in turn has improved the reliability of his system by Mr. ITerbert McLcod's papers " 0« a New Form of Apparatus for Gas Aua'ysis." in tho September number of the "Journal of the Chemical Society." 1S6U, and " Apparatus for Determining tho Quantities of Gases Exists login Solution iu Natural Waters," in the "Journal of theChemlcal Society," Vol. series; and Dr. Russell's paper read before the Ilrltish Association, 18C9.

It Is at present difficult to determine which is absolutely the best With our present knowledge, perhaps, theoretically Fraukland's Is tho most accurate, but a systematic research mny nt any time turn the tables, a'ud leave Wanklyn's the best, while chemists are undecided, mauy taking each side, while others, the majority, take neither.

Neither the alkaline permanganate process of Prof. Wanklyu aud his colleague nt the London Institution; nor the gasometrie system of Prof. Fratiklnnd, aud tbo Royal College nf Chemistry, however, aro periect, and, strange as H may seem, neither of them are capnblo of correctly aud accurately estimating the actual amount of tho nitrogenous organic ms-tter. as Dr. Phtpson and Mr. Paul remark. It is true Dr. Fraukland, in his article in Vol. XX, page ~l,ot the" Journal of the Chemical Society," goes solar a« to deny ltspractibilitv at present, but that is too sweeping a conclusion. At present, therefore. Professor * mnklnnd я system ied In connection with the Royal Col lego of Chemistry nppnratus. as detailed In No. SI of the new scries of tho " Journal of tho Chemical Society,' and by experienced hands, is theoretically the best, and in practice «m) yield tlio most accurate results, liut, on the other hand, it is lotig, difficult, and complicated, utterly unreliable in inexperienced hands, und, from its verv complication, liable to erave errors, which the number of reductions aud calculations afford every ohaoccof bolng increased to a serious extent in passine through theso manipulations. These, in eonneotiou with other matters, operate to such a degree as to render it possible ihnt no two analyses of the same water will agree.

Finally, therefore, in practloe. Frankland and Armstrong's process is not to be depended on unless a long series is taken, aud the avernee struck olí ; while its complication, difficulty, and length, together with the complex apparatus aud many reductions and calculations, render it so liable to serious errors as to

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quite outweigh the advantage it has of aífording the total empirical formula of the organic substance. It also has the disadvantage of giving no easyhtandard of comparison with others, and of not in tho slightest classifying the organic matter.

Messrs. Wanklyn, Chapman, and Smith's process is indisputably the shortest and, aud moreover is such as can readily be done by anyone, it enjoya the advantage! classifying direct the nitrates, nitrite», ammonia, urea, and albuminoidous and nitrogenous organic matter into separate élusses. It is very'little liable to error, and besides affording: no easy standard of comparison, can always be depended on to afford an exact agreement in Us result between wstert of the same composition.

It пае been alleged against it that with waters containing the same exact amount of nitrogenous organic matters, but of different constituents, it will yield different analysos, and that with waters of different quantities of oxydieed and nitrogenous organic matter of different constitution it will yield similar results. This is true ; to a slight extent it will, but the ¡tosometric system does the same to a far greater extent. It has also been stated that Messrs. Wanklyn, Chapman, and Smith's, permanganate of potass process naffer» under the objection of being liable in a certain degree to under-estimate the nitrogenous matter; this is also, to a certain extent, true, as it is indisputably passible for it to so happen, but it could only no occur with perfectly harmless compounds, not known to exist in water, and then to but u very small degree. Messrs. Frankland and Armstrongs gasometría system labours under the much more serious difficulty of being- extremely liableïto very considerably over-estimate the nitrogen, and of confounding the innoxious and the dangerous nitrogenous matters together.

From the above, your correspondent "AV. It." will gather that personally I am of opinion that at present, for general purposes, Messrs. Wanklyn, Chapman and Smith's permanganate process is the best, though for some purposes, Messrs. Frankland and Armstrong's gasometric system in preferable.

In reply to his queries, It is possible to use both Wanklyn and Frankland's process for sewage analyse-a aud, perhaps, for that courseof analysis, it would be as well to estimât* tho total nitrogenous matter by Frank land's system, and confino Wanklyn's to freo ammonia, urea, and albuminoids.

Nessler's test can satisfactorily be employed for estimating ammonia salts, nndforsmall quantities is much better than standard acid.

Finally, it is practicable, but not advisable, to uee Wanklyn's system for manures; neither should I recommend Fraukland's. Urban.

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TESTED RECIPES.—" Л Morayshire Man " says: —" I am of opinion, with a number of otberjeorrespondents, that those furnishing answers to queries for recipes should add whether they have been tried ami proved, or, if they were extracted from some author, as the caso may be. I am confident a number of these answers are not worththe space they occupy, aRd, consequently, a Joss of time and money to many a one who tries them, both of which the person may bo ill able to spare. And with a few consecutive failures, many л person may become disgusted with tho recipes (never bbimlog himself of course*, and if not the loss ot a subscriber to the Mechanic, at least the lose of a correspondent. I have found a number of these recipes useless. Not at all times so much the tanlt of the recipe itself, as to the manner of preparing it."

THE EAR.—"H.dcS." ?aye:-"Dr. Usher wiftes oí having often been an hour in removing a plug of wax, and add» a caution against the common and indiscriminate use of the syringe. Will he allow me to Inform him that glycerine dropped into tho ear dissolves 1hc cerumen, which is occasionally secreted iu morbidly excessive quantity in the outer meatus ot the ear in old people and in young children; and al-o that in certain forms of deafness, arising from a deficiency cf the waxy secretion, it works often like a charm when dropped into the meatus, so as to lubricate that passage and the external surface of the membrana tympauiV For this I am indebted to Dr. Abbotts Smith's two little books ou glycerine."

MIND AND BODY.—Edmund Lawranee says :— ** lïemg deeply interested in the subject of * Mind,' I joyfnlly hail tho appearance of Dr. Maudsley's lectures in the K.NOLisn Mechanic. MancoushUsof two parts only—soul and body Mind is the actum of tho soul. The soul per te is not only ignorant and dark, but totally unconscious of its own existence; as, during perfect sleep, a faint, or upon concussion of the brain. When, however, the nerve waves arc set iu motion, the soul not only becomes conscious of existence and recipient of present impresione, pleasurable or painful, but ft also finds it has the faculty of marshalIra* and reviewing the impressions received and rfcgUtercd by the nervous system during a whole lifetime, llut the soul is utterly dependent upon the inte&rltv of the brain register. If the images be distorted or misplaced by disease, the Mmii still accepts those in simple faith, and, attempt ing to re;;«on upon tliem, produces the well-known phtimmeua of insanlry."

COTTON SPINNING.—"B. H., Rochdale" writes: —" I hsvo rend with in tere» t the several letters on 'Cotton Spinning,* on pace Island 183, and in reply to * II. С S.'s' assertion that there is tiut, or ought not to be, any draught between the lap roller nnd feed rollers, he" cannot have examined the question in a proper manner, or he would liml thut It isas needful in that part of the engine ns any other, although it is

1 very small—say, I —In. With respect to the rule he

10 grives for the draught of drawing roller?, he imperfectly rieht, an far as computing them together goes, »Hil E. Slater will find that by his rulo fíf he gives the rollen the proportion he has set out, and then takes

the whole draught of the rollers together) that hu has a draught of VZ instead of 7."

READINGS FROM THE GLOBES.—J. Dyer Mates.-— "lu 'T. S. II.'s* letter, entitled 'Readings from tlic Globis,* at rage 208 of the English Mechanic, the following statement is made:—'As the globe turns ou its axis from west to east, those who live in west longitude must have their time earlier than those living in ea«t longitude, because they will not come Into the enlightened hemisphere so soon.' The word carlUr should be later. As the sentence stands, the last part contradicts the first."

THE WANDSWORTH TELESCOPE.—E. Salter says :—" Having recently coinc to reside in this locality (Claphnm Junction), and notieingMr. Webb's late remarks respecting the great Wandsworth Telescope, I havo been induced to try to seek It out. After two or three failures I met near the spot on which It used to stand a gentleman named Stilwell, au inhabitant <\t Wandsworth, who gave Ine the following particulars from his own personal knowledge. Pointing out the enclosure within which tho instrument was erected, and Indicating marking* In the ground left by the tower from which it swung, he said that the whole affair was removed fonr or five years ngo. The bricks were employed to aid in the erection of nn hotel visible a few hundred yarde off; the tube was bought by a Wandsworth broken, who cut it into section*-, and sold them to a gentleman at Wimbledon. These sections, with bottoms inverted, formed tanks, Ironi which the gentleman'« cattle now drink. About the tramway there was some four tons of wrought iron, which Mr. Stilwell himself had converted into horse-shoes. As to tho object glass, my informant could tell me nothing."


[2007.]—TEMPERING PRILLS.-If the drill is a small ono hold it in a jet of gas till a cherry red heat appears, then dip tho point, or as far up as you wish it tempered, into water or oil immediately. Then try if a smooth file will bite or file it'; if'it does, it must be done over again, but if it does not bite, but blips over the face without making any impression on it, it will do. Next clean the point or side oí the face carefully on an oil stone, then twist a piece of wire round the end of the drill, or hold the end of the drill in pliers, or a candle or gas light till you see it (on the clean piece of the face) grsdually turn from a light to a dark straw colour; withdraw from the heat, and allow it to cool gradually. If it goes past the dark straw colour to a blue it will be rather soft, and must be dipped in water or oil at once, orels'- the process gone over again. The above dark straw cjlourwill bore brass beautifully. If it is to bore steel or iron. 1 have mine just as hard as when they come out of the water or oil in the first process, but care needs to be taken with them if very small in that condition, as tney are very brittle. I have made several dozens in the above way during the last 14 years I have been working at my present profession. —A Morayshire Man.

[21*1]—BAROMETER TUBES.-" Compensation" can clean his barometer tubes by washing with soap and warm water, and drying in an oven, or on a stove; or wat*h with spirits of wine, ami it will dry itself when the spirit evaporates, or if the tube is very dirty, I have used fine sand with soap and warm water. But I do not approve of the sand, because it is apt to scratch the inside of tho tube, which causes more irictlon on the mercury rising in the tube, aud consequently tho barometer cannot be so correct.—A MoRayshire Man.

[2363]—SILVERING CLOCK DIALS.-If "Poor Clock Jobber," 23«, pago tu*, conies the recipe"giveu him by "Л.М.. Birmingham," into execution, without further or fuller instructions, he will find his clock dial in about two or three months covered over with green spots, not because the recipe is a bad one. It is good if fuller explained. If " Clock Jobber " will put a piece of silver in a tea cup, cover it over with nitric acid (aquafortis), he will find the acid begin to boil. If it does not, hold the cup over a jet of ga-*. or put it on a slow fire till itbegins to boil. Take If »1Г the lire, and it will boil away tlil the silver la dissolved. If he require* more acid (owing to the acid not being pure) he can add a little, but the first quautity should do lor dissolving a Öd. When dissolved, ho will have a green deposit. Fill the cup with warm water, stir well to wash the silver, throw in gradually ns much tabic salt as a penny piece will lift, delist stirring after tho salt i M put in, ami allow the solution to settle a few minutes. The salt will oncipitate the silver to the bottom of the cup. Pour i IT the water in tho cup, care beiug taken not to pour oft auy of the solution, and when poured oil as clean as can bo without taking any of the solution wiili it, evaporate the remainder of the moisture above a jet of gas, or otherwise, till the solution is in a thicklsh kind of paste ; when this is done, fill up :he cup ngain with warm water, aud repeat tho process till the solution comes toa milky whiteness, and you are eure all the nitric acid is out of the solution. Two or three washings is amply sufficient; if any trace of the acid remain it will in time (notwithstanding the varnish) cat into the dial or other article, causing a number of greens potH to appear,as it were, on the surface of the silver. "Poor Clock Jobber" will at once see the advisability ol well washing his solution. Tho parte to be silvered must be well cleaued with lino Hour, emery sheet, or paper. No grease or dirt must touch the article, especially when finishing, not even the hands must touch it if possible. When well cleaned, and all traces of previous silvering, or lacquering off the article (I would not advise "Poor Clock Jobber" to wash the article at this stage of the proceedings), take a piece of wash leather or soft cotton rag, soak it in water, dip it in a little salt. Rub the dial over with this fimt, pretty smartly. This makes the solution take on better. Then dip the rag iu cream of taitar, and also iu the solutiou (for they may be mixed

together), and rub woll on. and if this does not silver "Poor Clock Jobber's" dial, I shall be apt to say with the Editer (see p. OS). After it is well silvered, wash in clean water (only). Dry with a soft towel ; when dry hold the back of dial close to a lire or on a stove till it heats a little, not to be so hot as to melt the wax in the chaînera. Then varnish with a soft brush, varnish to be mude by dissolving gum mastic in spirits of wine; the varnish requires to be rather thin, and the article will be ready in five minutes to be sent home, I havo done tho above frequently with brass dials, aud found no trouble with them afterwards. "Poor Clock Jobber " may think I havo been too long in answering the above. Rut to explain, I get thc3lECHANic ouly in monthly parts at the beginning of each month, aud when it leaves the bookseller's snop from whom I got it, it comes Is miles by rail ere I get possession oí it, the carriage by rail of which I pay over and above the regular price of publication.—A Morayshire Man.

Г2445.)—GALVANIC BANDS.—Tho width of metal strips for galvanic bands is of no consequence : the broader the moro action. I have generally made them about îin. wide. To "whip " tho joints with thread Is merely to wind thread rouud them in a close coil. List is the woolly selvage from cloth, for which ask your tailor ; It matters not which side is worn next the skin, provided the bare metal at the end of tho band touches it.—Suffolk. Amateur.


opinion is that if the boiler is properly fixed at tho back of the kitchen range, the flow and return pipes properly erected from the boiler to the hot water cistern, a water gaugo would be useless. For this reason, when hot water is drawn for use, it is not drawn from the boiler but from the hot water cistern, through pipes connected to the return pipe. Consequently when there is no hot water, it is a proof that the cistern is empty, and not the boiler, and a fitter is callod in before any damage is done to the boiler.— J. O.

[2528.]—MUSICAL. IIOX.—From tho poor way in which I expressed myself on p. 164, I may not quite be understood. The Wtb and 17th lines should read. "The right end of the roller comee slightly over the edge of the same (thtVs the roller), and is caught in a


[3567.]—CHIMING CLOCK.-If "Toodles" will gel three or four spiral springs something like what are found in the inside of couches, easy chairs. Ac, lay them in the bottom of his clock cose, lay a flat board on the top of them, or a bag of wood shavings, hay or straw, he will find that when the weight falls, coming in contact with the springe they will cause the weight to rebound, and so break tho rail,—A Morayshire Man.

[2577.]—BORING GLASS.—This questiou relativo to cutting circular holes in glass, does not appear to have been satisfactorily answered. As I, some time ago, required certain glass'disoe with holes in them, 1 went to Palmer's, in St. Martffl's-lane. and I will, with your permission describe how i heir cutter proceeded. There was. on alow table, a circular disc of about a foot in diameter, covered with cloth, and mounted on a pivot, so as to revolve on Its centre, and there was a mark to indícete this centre on the top of the disc. Then there was a firm upright fixed in the table near the circumference of the disc. Through a hole near the top of the upright slid a graduated arm, aud to tho end of the arm was affixed a glazier's diamond pencil which could be slid dowu so as to bear upon the disc. Now supposing I wanted n circular plate din. In diameter, with a hole Iu tho middle of gin. diameter. A square of glass of rather moro than fiiu. in the bido was placed ou the disc, the arm was adjusted so as to bring the diamond to bear at 3fn. from the centre, thedTsc was turned by tho hand, ami a circle of (Hu. thus described on the glass; the arm was now set at lin. from the contre and the inner circle scratched. The glass was then removed and placed on the usual flat cutting boaid, a rule was applied and a few cuts made with another diamond from the outer circumference to the sides of tho square. This enabled tho workman to remove the superfluous glass from the outside of the circle. He then applied the rule again, and made S or 10 cuts across the inner circle, and crossed these a^ain with about as many more. Theu taking the g hiss in hU left hand, and a pair of iron pliers iu his right, he began tappiug lightly on the part that was cross cut, when nearly the whole fell out In fragments, and any obstinate pieces were taken off with a grasp of the pliers. The whole process was gone through with •rreat radidity, and was very dexterously done.— F. IL С. S.


II V = — x я- (R3 + r2 4- Rr) = 4 x 3,1410 (1 + 1 + 3

2xl) = 12-5004 x 7 = 879048
440 11

which, multiplied by or — gives very nearly 17

3240 50 tons 37. By a simple error of copy our friend Mr. T.

put 10 for T.—1ÏEUNARD1N.

[2000.1—CLEANING OF DIATOMS.- -Thanks to Mr. Anderson lor his kind reply ou the above, which I hope will give the desired result. In answer to Mr. A.'s query as to where 1 gather Diatoms, 1 may cay that in spring they are to be found in almost any kind of water. There is a small brook near my home, which I have hunted for a mile or two, and here aud there where branches of trees and other obstructions lio across tho stream, so as to be only partly submerged, I have several times discovered the Uerp brown yensty teumt which betokens the presence of Diatoms. The most successful gatherings 1 have yet made, were iu ditches cut amongst osier beds Пну may be found also iu ponds and ditches; If reetis rushes, Jtc, be growing la them, so rauch the more likely are tt;cy to contain Diatoms. I have found the following:—Amongst the Àfuieulœ, Л*. KAo»iboiJt*t Л*. J.nijhisbtrna,y. írVííii N. IMJymt. Plmrosigirue I*. Âttent».tvn, i*. JmjittatHM, 1*. Speu'cerU, Сиспяела Lnn-eolatvm, ГиииЦвпа viridis* ОомрАонсшл t'apttatntn, /£нсуонемл axpitosum, and several others, many of which I hare not yet identified to my satisfaction, as I am only a beginner in this interesting study.—Beaten.

[2634.]— PAPER HANGINGS.- As a continuation to A. Boughey's Information (which applies only to what is termed block printing) the question asked referring to machine printing, in machine work there are three principal divisions, viz., pulps (plain), grounds (coloured), and satins (both coloured and glazed). The first is printed plain—that is, without any preparation; the second is coloured with either white or any tint that may be required, and then printed; the third is coloured and polished before it is printed. To make grounds there Is a grounding machine (of these there are several sorts); the colour Is put on by it and smoothed with brushes, after which It runB through a long hot stove to dry, and at the end is formed either into folds or rolls, according to circumstances; it is then ready for printing. Satins are made somewhat similar to grounds, only that they have to go through what is called the polishing machine to be glazed. The printing machine is cylindrical, with revolving rollers pressed against It, on whose surface is placed or cut the pattern or form wbich each roller is intended to produce. When dried the printed paper is taken to the rolling machines and cut by young girls into pieces—Practical P.S.

[5M10-GALVANISINGCASTIRON.-The method is essentially tbo same as for sheet iron, but there is more difficulty In getting the zinc to adhere.—J. Meredith.

[2067.]—PAINT TO COVER TARRED WOOD.— All paint is affected when on a tarred surface, and the colour is generally turned to a green tint, a coating of lime, white wash, or two, would answer the end desired.—J. Meredith.

[2676.]— MODEL STEAM ENGINE.—"C R." was right when he said the model engine he Baw had a cylinder, pteton, fly-wheel, &c. Steam ouly acta on the piston during half a revolution of the fly-wheel, as will be seen by the following. A small block of metal is


fixed to the side of the cylinder at A, the face of which works steam-tight against the block II. The piston rod is fixed directly to the crank pin, so that when the engine is in motion the cylinder oscillates upou the pivot C. There are two holes in B, one the exVaust and the other the steamway. The hole in A serves for exh&uBt and steamway both. The action will be understood by examining the drawing. — W. H. Thorpe, Reading.

[.M79.]—HOW TO CURL AXD CURE HORSE HAIR.—In the first place I teased the hair well, then twined it into along rope with a hand twiner with the assistance of another person, having rolled it up into a ball, steeped it in water 24 hours, after that put it into an oven, taking care that the oven be not too hot to singe It; alter getting perfectly dried, I began to teaze U again, it is now ready for use. such as stuffiiug chairs, sofas, &c—A Helper Out Of A Fix.

[2683.]—IRON PALISADINGS.—The durability of ordinary paint or varnish would much depend upon whether the surface was free from rust or not. I would advise the use of Webster's patent zinc paint, which may be had from the patentee at Ozels-street, Birmingham.—J. Meredith.

[2693.]—KEEPING COPPER PLATES FLAT.Try reversing the plates.—T. S. U.

[2095.]—GEOGRAPHICAL QUERY.—" Key," as a correspondent, has said,is metimes the meaning of "quay," but also in several German languages " keizel, kef," has the meaning of flint or stouc. Let me propose then the translation "netber set key"—a stone where burdens were Bet down, or, a stone for sitting on; key-house, a stone-built house; "kcy-spink '*—stone finch, stone sparrow, the doubtful sparrow, FringiUa petroiiia, Linn. Those acquniuted with the locality will decide if lam right.—Bebnardih.

[3598] — " EMIGRANTS'" INQUIRIES. — Upon reference to a map it will be seen that Australia if nearly at the same distance to the south of the Equator as England is to the north; in fact It lies very near our antipodes—that is, if by any means a Hue could be drawn directly through the centre of the earth from this country, Australia would lie near the point Jit which the Hue appeared upon the other side of the world. It may, under these circumstances, be at onf«inferred that Australia possesses a somewhat similar climate to our own. Climate is influenced by many local features, and to these we iniiBt assign the differences of temperature which exist between tintwo countries. Australia, however, is superior :o

England In many respects: its winters are not so cold; its atmosphere is neither so foggy nor so damp; but is uniformly genial, mild,and dry. The summers, although occasionally much higher In temperature from the prevalence of north-weft winds blowing from the heated coast of Asia are scarcely so enervating or trying to the constitution from the bracing nature of the sea breezes. Beyond this the purity and freedom of the air from miasmatic influences and the usually noxious effects of night dews are such that a person may sleep under ll the open canopy of heaven" at night during the greater part of the year without endangering his health or constitution. Regarding the colony of South Australia more particularly, I may say that generally the above description of climate is applicable to this part of the continent, although of course the proximity of mountains, rivers, arms of the sea, &c, will cause slight differences, according to locality. The resources of this colony are chiefly mineral, yet agriculture and sheep-farming are pursued to an enermous extent. The colony, however, may still be said to be in an embryo ftate, and Is capable of sustaining a population of probably not less than 50,000,000 of people, whilst at the present moment there are not more thau between 1 or 200,000 scattered over Its enormous extent The land 1b fertile, the yield of grain being large; of carefully cultivated, giving frequently OtTor "Obshl. to the acre. Its capabilities have been briefly summed up by one of the governors as \ adapted to agriculture, h to pasturoage, and 4 barren and unfit for either. The above will give J. Francis some slight information about the colony. If it is too superficial, I am ready to enter into detail, but wish aa far as possible to condense this kind of writing, so long as the required information is imparted, so as not to occupy too much space. No one should emigrate to South Australia who is afraid of work. Do not go there with a firm intention to stick to your trade, for the probability is that you will find yourself before long lollowlng thecalllng of a shepherd. There is no shame in this, doctors and lawyers, Ac, have tried their hands, and have succeeded admirably. The man who can handle tools, mend carts, repair farming imp lements, Ac, is fortunate, be can command higher wages than his more unskilled fellow, even if employed upoa a sheep-run, for being at a long distance from a large town, resources at hand arc of great value. The best time of the year for sailing from England is during the autumn, as you will then arrive in Australia duriugthe summer. I cannot state the best placo for your ultimate destination ; the demand for labour varying, as in all other places. Speaking of the neighbouring colouy of Victoria, Mr Westgarth says:—" Hence a long array of miscellaneous arrivals, new and old, contiuuously out of work, while the skilled workman—the blacksmith, the carpenter, the stonemason- is but little beholden to employers, tights with them successfully at times over an eight hours' instead of ten hours' labour question at the same wages; and withal, in a country uowon the whole cheaper to live in than England, carus as much in one day as manv a home family must be content with for a week." This is a Ilttl; exaggerated, for which allowauce must be made, (Books consulted for information—"Guide to Australia, by a Merchant;" "Westgarth's Colony of Victoria;" "Maury's Physical Geography of the Sea;" "The Harrow School Atlas "—EssaysJ-F.R.G.S.

[3703.]—PASTEHOARD.—Screw them up in a napkin press before they are quite dry for 12 hours ; air them and repeat the process. 2nd, paste the edges of the first sheet of paper on a board or door; add as many sheets as yon require for thickness, and cut off when quite dry. 1 have made equally good boards by both methods.—T. S. U.

[3706.]—PANCRATIC TUBE.—This may be Illustrated on a small scale with any telescope. Unscrew the eyehole, draw out the small tube containing the two eyglasses us far out us it can conveniently be held by the lingers to be steady, and push in the focusing tube for distinct vision. An immediate increase of magnifying power will at once be evident In all glasses with this appendage, the eye-tube mentioned above is contained within another, to wbich the thread of tlie eyehole screw is fixed, instead of to the outside polished brass tube. Iu Solomon's 3in. telescope, this tube reaches nearly to the field glass (the 4th from the eye), so that when fully drawn out, the length of the day eyepiece Ik doubled, and the sun and moon can he distinctly examined throughout the length of the tube, the magnifying power increasing according to iu lenptb. Itis so long since I had them made, I forget tlie price, but should say from 4s. to 0s. Can be made bv any optician. With a clear-sky and good light this tube is equally applicable to terrestrial objects. Kor this telescope, I find the "Dean disc ulass" for day powers, supplemented by one of deep blue for solar observation, answers perfectly, absorbing all the glare, and reducing the suu to the brightness of

2 a white cloud. For a 2 — In. telescope, I find a glass

8 of "London smoke," one of deep and one of a lighter blue required. "Dean's disc" of " London smoke" may now he hud from Messrs. Solomon** lor 4s. 0d., the other glasses will be cut by any plumber for a Id. each.—Amateur.

[3709,1—TURNING.—There Is an error; the word "never" should not be there. It reverses the very meaning of the answer. It should read "An amateur will find a coarse, sharp, new flle," &,c.~ Q.


[3700]—TURNING. — Sec answer amongst the Letters.

[3710.]-ARITHMETICAL QUERY.—If C c, represent the circumferences of any two different circles, aud D & their diameters, then

C : c ;: D : d

This fixed namber is generally represented by too
Greek letter ^ (read pi), the first letter of the word
periphery or circumfereHce. So that if

— = 7T


C = 7T X D

Now this number is the same for every circle, and it is obviouB that a single accurate measurement should be sufficient to determine it. It might appear at first sight that nothing can be more easy than to lake a perfectly constructed circle and measure Its circumference with a cord: and then measure the diameter m like manner, and find the ratio of two measuremeuts, which will give the numerical value of jr But It is found that the ratio of, the circumference of a circle to Its diameter cannot be exactly expressed in numbers. Each separately cau \<v measured with perfect exactness, but both do not admit of being measured exactly b y the same linear unit, however

22 1

small that unit may be. Practically — or 3 — is

7 7

found to express for many purposes with sufficient

355 exactness the value of j: — is still nearer, but

113 3 1410 or 314159 Is In general use. Now, suppose we have a regular polygon with a perimeter of 8 and number of sides 4. i'hen 1* is the rad. of inscribed circle, and 1-414213 is found to be the radius of circumscribed circle. Also if we have a regular polygon of 4<WJ sides with the same perimeter, the rad. of inscribed circlets 1*278239, and that of the circumscribed circle Is the same. Thus the circumference of either circle will not differ from the perimeter of the polygon between them by a quantity sogreat as '00001 because the radii do not. So that wo may conclude that the circle whose circumference is 8 has a radius equal to> 1*373239 But

circum. circum.
Jt = or

2 x rad. diam.

[ocr errors][ocr errors]

C : I>:: c : d

D d

or the circumference of :i circle bears an invariable ratio to its diameter, aud of course to Its radius.

The area of a circle ll found by the formula (diameter) *x *7854. Now the circumscribed square is equal to the square of one of its sides, which is equal to the diameter of the circle. Therefore we must multiply areas of squares by the decimal -7S54 to net areas of circles; and not areas of circles to get area oi squares.—J. G. G.

[8717.:—COFPKR AXD SILVER COINS.—The first is a Kreucli coin of Duke of Rohan ; the second an Arabian.—Collector.

[8718.1 -TALL CHIMNEYS.— The great chimney at St. Koltox, Glasgow :—

Total height from foundations...
Depth from foundations

Total height above the surface

Diameter at base

,, surface

,, top

There are used in its construction l,2i0,000 bricks of first quality, weighing 1211b. per cub. ft, the brickwork is 31 bricks at the bottom, aud 1J at top. Tlie peculiar construction Is that of a double cone, the Intern >il flue is200ft. high, and la perfectly vertical.— E. N.

L:1721.]—GRINDING.—In answering the inquiry of "Scrgius," I should Bay that 4 bush, per hour, more or less, was a fair avernge for a 4ft. stone running 120 revolutions per minute; but 200 revolutions for a pair of 3ft. 4in. seems to me too fast. Terapleton gives 150as speed for Win. 6touc.dividiug6 00 by the diameter iu inches; hut it is a bone of contention with millers as to how much a stone ought to do, even wilh plenty of power; some not liking to do more than 3 bush., others will advocate 5, much depending on the stone at d the dryness of wheat: and I should not be surprised if my letter gives rise to more controversy than the balancing business, of which so mnch difference of opinion exists—solely, I believe, because a stone that is in standing balance is generally in running balance, or so near to it as not to be felt when there is a moderale amount of feed uuder: aud I believe there are millers who would boast a life of experience without knowing their stones were out of a running balance, Bimply because they never ruu them empty to try. I have i pairs of 3ft. loin, which will do 4 bush, per hour well. I have also a pair of 4ft. Oin. which will do 10 bush, per hour well, aud work well, hut they have 5im. draft. These said 4lt. (iin. had formerly 2in. draft, aud 1 understand they would ouly do 4 bush, per hour; the alteration was made by running all the furrows into the master furrow; thus making a second furrow of the master furrow. There is a pair of 4ft. 4in. laying beside them, both driven by wind, running the same speed; but they will not do so much by about 3 bush, per hour, although thev had the same alteration made iu the draft and furrows at about the same time—say 40 years ago. Now I have seen these two pairs of stones do nearly a load of wheat iu 2 hours. We find no disadvantage from the extreme draft, but dare not carry much furrow.—One Kye.

ni723.]-GrfAZE Fun I'OTTKRY.-IOO parts white lead, 20 do. Hint, 40 do. Hint, 5 do. whiting. This glaze Is colourless; to make it a brown ghizondd IS parts of oxide of manganese aud 18 parts more white lend; to make a blue glaze, substitute for manganese 9 parts of oxide of cobalt. Shall be happy to afford "X. N." any information he may require upon this subject.—K.

[3798J—GLAZE KOR POT IKIIY.-Ccmsult specification of Patent 3'57, 30lU October, 1*07, at your




¿Barest publie free library, which I think may give "*" Information you require—A. Tolhauben. fa?.».]—VULCANISING RUBBER — The rubber uiy mixed with sulphur for vulcanising, may be obavd from С Macintosh aud Co., Cambridge-street, Manrhcster.andLondon,orDnvid Moseley, Manchester She price will depend on the proportion of sulphur, required, which varies for each special purpose, perb»ps 2s- <xL or 3«. per lb., in quantities. Too moulds abonlil be pure tin or plaster of Paris. Iron combines ■with the sulphur, and destroys the nature of the rubber. Any steara tight chamber may be used for vulcanising In (which will stand the pressnre) Information respecting the time required, and the pressure, may be obtained from the persons who supply the rubber, or you might try a pressure of 50 or 551b. on the In- for!) or4 hour*. When you get it exactly as you want it, adhere strictly to the same timo and pressure, a» the »lightest variation alters the nature of the rabber—A Dentist.

[3725.]—OILED PAl'EU.—Hausol. of Neustadt, recommends petroleum applied to writing or drawing Caper, and properly dried by Molting paper.—A. OLHAOSEN.

[S730.]-PAPER COLLARS AND CUFFS.-A neat machine for the manufacture of collars, cuffs, and other articles of dress made of paper and cloth combined, ■was patented by Mr. Benjamin Browne, in 1868. The material Is first operated upon to represent stitching, ercaecd for folding, the button holes punched, and the ends cut off to the desired shape; the article is then discharged from the machine, and another feed of paper supplied and operated upon as before, and so on <n succession. Finally the article is passed by an endlos« belt between rollers for finishing it (vide specification, A.D., 1808, 10th March, No. 1040).—A.


[57»]—COTTON SPINNING.—J. A. Hulsse,"Die Tichnik der Baumwollspinnerei," Stuttgart and AugsbuTg 1S57 : J. D. Fischer, " Dir praktische Baumwollsplnner," Leipzig. 1865; C. H. Schmidt. "Lehrbuch der Spinnereimechanik," Leipzig, 1867: К. Karmarsch, "Handbuch der raech. Technologie, •• Hannover, 1858 -, Bd. S. 1006—1103—Supplement zu Prccbtl's Tichnolorlseher Encyclopndie, (Karmsrsch), Stuttgart, 1S57. The above books may be had in London. Trubner and Co., Paternoster-row. Benno Niese, " Die Baumwollen Spinnerei in all Ihren Theilen" Voigt in Weimar; Dr. E. Hnrtzlg in Dresden Versuche über den Kraftbedarf der Maschinen in der Flachs und Wergsplnnerel; Schweiz. I'olyt. Zutschrift Vol. XIV, Heft 5. Sute 126,—A. Tolhauben. • [37.Ï9.J—CHLORIDE OF TIN.—Three chlorides of tin are known, corresponding to the oxide", namely SnCls, SnCl«, and SnCU. See Watts'» "Diet, of Chem." voló.page 8(41.—A. Solhausek.

[3739.1—CHLORIDE OF TIN.—If this querist will ask at a manufacturing chemist's for protochloriJt of tin, he will most likely got what he requires —A. T.

[3741.]—TURBINE— In answer to " M.R.C.S.." if he will write to me I will try to assist him to see a turbine, as there arc three in my neighbourhood.— Jon» Wild. Shuttlcworth, nesr Bury, Lancashire.

[3750.1—SILVER COIN—Is a penny of Baldred, King of Kent (the last). Obv. : King« bust to right; Baldred Rex. Rev: Moueyer's name — Edelmod Monet«, small cross, 7 rays Issuing (scarce). Should be glad to communicate with "Beginner."—J. H. D., Stretton-on-Dunamore, Rugby.

[3751.] —ASCARIDES.—A great sufferer from ascarides should take SO drops of tincture of iron In Inf nslon of quassia twice or three times a day for a month, and use an injection of common salt dissolved la water, but not made too strong, occasionally. This generally succeeds, but cases differ, and no case cau be satisfactorily treated by correspondence. Any chemist can make up the above prescription,—M.D.

[3753.]—BOTANY—A "Manual of Bo tany,"by Robert Bentley, Professor to the Pharmaceutical Society, published by Mr. Churchill, las.6d., Is the standard work apon which the students are examined, and is decidedly the best.-F. H . H.

[3753 ] — BOTANY. — Use Babington's " Manual of British Botany," or a similar work by Johns. The latter is more popular, and easier to work with, and costs about 7s. 1 believe.—M. D.

[3762.]-PAINTrNG AND DECORATION.—The best work on house decoration and painting that I have seen, is by William Sutherland, Manchester; obtainable from Simpkln, Marshall, and Co., Stationers' Hall-court; Abel Heywood and Son, 5« lad 58, Oldham-street, Manchester.—Pamteb.

[3703.]—THEINE. — I perfectly succeeded in the Isolation #f théine by operating on 31b. of the best

freeu tea as follows :—2gal. of distilled water, where rought 11 the boiling point in a still of 4gal. capacity; I now shoot in the tea, stir up for an Instant, quickly late the head on, connect it to a worm condenser, and ebullition commences. Ity the above arrangement of apparatus you will observe I was able to collect, previous to the Isolation of the thelne, another highly Important compound of tea—viz., the essential oil. Noto also, by having the water at a boil I avoided the risk of charring the leaves, which doubtless would have occurred if the still had been placed over the are with cold water along with the tea. I kept it gently boiling for two hoars. About lipt. of water passed over loaded with the oil. On agitating this water with ether, decanting and evaporating the ether, I obtained the oil in a separate form. This oil appeared to me to be a powerful Intoxicant, for on my warming it and 'applving my nose, it had an effect similar to smelling hydrocyanic acid of high per centago. I now set to work for the thelne emptying the contents of the still on to u brown calico strainer suspended from spike« on a frame furnished with four lege, allowing the Altratc to run into a large tin vessel. I now pour 2gal. more of distilled water into the still, which 1 place over the lire; I collect the leaves off the strainer Into a dish, ami submit them by portions to powerful pressure in a tincture press, allowing the expressed liquid to flow ou to the strainer. The hard cakes of leaves from the press I knock aud break Into

{lieces. crumbling th^m into a loose heap. The water n the still is now boiling, the leaves are shot in again

and stirred; not the bend this time, bnt a lid is put on. It is now left for two hours In brisk ebullition, then strained and expressed as before. A boiling solution of subacetate of lead facétate of lead 5 parts, litharge Si parts, distilled water 16 to 20 parts, boiled for half an hour) is poured In just na it is (without filtering) till it ceases to occasion auy precipitate. I allowed it to stand nil night to settle Early on the following morning I drew off with a syphon as much of the clear supcrnataut fluid ai 1 could; the precipitate 1 submit to pressure. I avoided the disagreeable process of sulphuretted hydrogen by the substitution of oxalic acid. The excess of lead was then thrown down as an insoluble oxalide. 1 added a little ammouia to take up the free acid, drew off the clear liquid, boiled it down to 2pts. or so, poured it Into a Jgnl. bottle, then allowed it to get cold (what beautiful eryatnls fill the liquid as it cools!); when cold I added .ibout 1 fluid oz of chloroform to the coûtent« of the bottle, and after briskly agitating them for 5 or 0 minutes I lot them settle ; the chloroform quickly fell to the bottom colourless and clear, whilst every crystal had vanished out of the liquid. The chloroformlc solution of théine was then taken up by a glass tube, drawn out to a capillary point, and discharged into a flask. The chloroform was then distilled off by a water bath into a Llebig's condenser, and on detaching the flask from the condeuser I found the thelne left dry and whito. It gave me entire satisfaction In the shape of a good sample of thelne. I should be pleased to bo equally successful with digitaline. Surely one of my brothor readers has attempted digitaline with as happy a result as mino as regards to thelne. If there is such a one among our many, may I beg of him to explain the way he proceeded ?—Pharmaceutical Student.

[Я7ПЗ.]—CAFFEINE OR THEINE.—The general method adopted in the preparation from tea or coffee is by pouring on these boiling water, and mixing the infusion with subacetate of lead to precipitate the tannin. Piligot adds subacstate of lead in excess, then am monta. The mixture is boiled for some time, the lead-precipitate carefully washed on a filter with boiling water, the filtrate freed from excess of lead by sulphuretted hydrogeu, and aftera second filtration, evaporated nt a gentle heat. On cooling, It yields an abundant crystallisation of nearly pure tbelne, nnd an additional quantity may be obtained by concentrating the motherliquid, and leaving it to crystallise. Caffeine being volatile, it mnyalso be prepared by sublimation, gradually heating waste useless tea in a sublimation apparatus, l'art of the sublimate I« quite pure ; the rest may be purifled by recrystallisatlon from water. For further details rhle " Watts's Biol of Chemistry," from which the above baa been extracted.


[3768].—POISONING BY CANTHARIDES.—The effects of cautharldcs are only trausient, and the results attributed (o It by the querist cau only exist in his imagination.— M.D.

[3778.]—LIGHTHOUSES.-The querist will find in "Merveille's dc la Science, par L. Figuier" all the particulars he may d-: sire ; every uumberof that work can be had separately ; lighthouses occupy, I believe, 5 or 6 numbers—BmsABDis.

[37Я2.]—BOILER—I do not know much about small boilers, further than their requiring much bigger fireboxes, in proportion, than large ones, onnecouutof the difficulty of keeping a small tire alight. For sucha boiler as w Hydraullean" figures, possibly a well arranged gas flre'would do I should, for a coal fire, put about 14in. square of Are bars, then elope the wall* of lire-box outwards at about 30° away from the perpendicular for, say, 8in., and then contract the walls again at about 4.1°, till your pot will just fit on. It is of an awkward shape to make a flue round to water level, and I should say seven 2* tubes would be better than one. The brick work might be gradually altered from square at bottom to round at top; and the reason for the form I euggest, is to get a great surface for radiating heat, besides what is conveyed up the tubes. I should put the dead plate on a higher level than the fire bars, eveu If it has to be made moveable for raking out the Are. Somebody who knows better than I. will, perhaps, give you a hint. I was very successful with a cylinder boiler only 4ft long, by 2ft. diameter, which drove an engine i\ diameter, and 8" stroke, for months, and the man In charge said he always had steam, and the fire-door generally open : of course only doing light work.—J. K. P.

pj94.]_P0LISHING STEEL-TO"CYLINDER." —Use your " red stuff" on a bell metal polisher, which can be had at any watchmaker's tool shop, and yon will get the black polish you so much ndniire. The scratches are caused by dust getting into the polishing stuff. The pivol "Cylinder" has marked A is a straight pivot, with the shoulder turned away after it is made. В is a cone pivot, which is proper lor a balance staff. The other is only sn attempt. Л cone pivot is made bv first turning down nearly to size, and then polished with a polisher, the shape made of a stick of straight steel wire. That part held In the band should be draw-filed, to prevent slipping in the fingers, and the other end filed the shape of a crossing file, to suit any shape, and give it a slight rotary motion backwards and forwards, as well as the longitudinal motion. This will prevent rings forming. When finished, turn a groove close to the pivot, to prevent the oil running up the staff, away from the pivot.—Viator.—P.S.—There are several other watchmaking questions asked this week; but the subject only interests the Individuals. I never yet heard of an amateur watchmaker.

[3801.]—WATCH CLEANING.—J. D. Morgan will require for watch cleaning, a pair of tweezers, plyors. cutters, a screw-driver, and a brush. I myself (an amateur; got my tools aud part information from the Watch Tool Warehouse, (.1. Fauenberg's, of Leeds); but perfection will come by practice.—N. T.

[3817.]-STEAMING WOO П.—The apparatus for steaming wood consists of a wooden chest, large enough to contain the work. This is connected with a covered boiler or copper, in which the steam is generated. "W. B." docs not state for wlmrpurpose he requires the stuff steomed, or the size of the »ame. «о that his query cauuot be answered satisfactorily. Large stuff requires

innre steam than thin stuff. An inch oak board wilt take about twenty minutes, and sets in two or three hours. In forming moulds for the hot timber to be shaped to, care should be taken to give a sharper curve than wanted, to allow for a alight reaction.—Boat Builder.

[3821.]—WHEEL CUTTING—In reply to .1. K., England, the teeth I cut were not wheel teeth, but Aoats similar to cabinet-floats, about loin, and 1 -'in. loug, for roughing the metal off the tubes that gun barrels are made of. The side view of them shows them to be like plt-saw-leoth, and skewed on the face of the instrument like the iron of a skew rebate plane. 1 merely wished to point out that the difficulty of having change wheel of steel did not lie so much in the expense of merely cutting the teeth, a» in obtaining the stuff to make large wheels of.—J. K. P.

[3822.]—FORCE РГМР.—It seems to me that "Guernsey Amateur" is sufficiently exigeant in wanting a drawing first made exactly to his requirements, and then to expect the Editor of the English Mechanic to go to the expense of having it cut and printed; particularly as he does not »eem apt at making an ordinary working drawing out Aud yot he can give a description of the action of a chuck that hcjhas'never seen. I hope he will not think I am pouring the vial of my wrath on him for the abuse I have received from an amateur in another of the Channel Islands. I think the best way of supplying u small boiler is to have a hand pump that will throw at least half a cubic inch of water at a stroke; and to supply the boiler that way, where you see by the water gauce that it wants it. Small pumps are extremely troublesome; at least, I have found them 'so. as you have ti> stop the engine directly the pnmp ceaees to act—viz., about once every half miuute or so. You cau pat а dummy, for the sake of appearance, to your model— J. K. P.

[3823]-SLOT CUTTING—Here is another Instance of amateurs not understanding a drawing, even with a description. The tool figured was meaut to be put in a drill chuck or else in a driller like mine, figured Nov. 12th, last year, and cither it or the work travelled backwards and forwards between two stops to regulate length of slot, and fed Inwards for metal

il about —in. or less during each trip. 1" In 5 minutes

103 is not bad work for a i drill to do, but I do not think the twist form of tool would keep on long at that speed. Mine was meant for wood, and shown with edges too keen for ordinary metal. I cannot glvo any time to this subject just now.—J. K. P.

[S833.]-FROM " BOAT BUILDER."—J. F. O'Brien does not say whether he wants a drawing of the whole canoe, or any particular parts. If the former, at lin. to the foot scale, it would bo too large for onr Mechanic, but If he will publish his address I will poit It to him. —boat Builder.

Г!835.]—CLEANING COINS.—I find the following effectually clean old coins so as to read the inscription. First lay them in vinegar, and then rub them with silvcrsand and water—Том С. Hollowav.

[3835.]-CLEANI.\GCOlNS.-J Nash will spoil his coin» if he cleans them. To decipher an obscur« inscription take a cast of the coin with wax, and я copy of that impression with plaster of Paris. This will show the letters much more clearly than the coin. When a coin or medal is completely worn smooth. If they aro heated red hot, say on an iron bar, the original Inscription will be generally quite easy to rend, although the metal of the cola iteelf is quite flat,—i>. YOKXE.


[3S38.]-PRINTERS- FURNITURE.— Would any reader inform me what plane they use in making printers' furniture, eepeoially regleta, and how they are held while planing them?—A Carpenter.

[3839.]—TRACING CLOTH.—Can any reader inferm me of a mean» of colouring оя tracing cloth (suchas used by engineers and architects), without injuring the cloth? Also, if there is any substance I could mix with the Indian ink, so as to make the cloth tnke on the ink more readily ?—Tracing.

[3840.]—MUSHET'S STEEL.—Will anv reader inform me, through the medium of your valuable paper, how to manage Mushet'a special steel, and what shape is the best for roughing tools: a small sketch will oblige. I have tried it many times, aud I find it too soft ?-J. M.

[3.841.] —GRINDING DRUG SEEDS —Will any klnd reader inform mo of a cheap and easy method of grinding drug seeds, fenugreek, se, on a small scale? —F. И. H.

[3842.]—STEEL WIRE.—Would the "Harmonious Blacksmith " kindly inform a musical mechanic, where to get some steel wire of different gouges, such as Is used for gongs in American clocks, or the gongs ready made would suit as well? The querist wishes to make a set of chimes, to bo put In a model church, and bells are too dear?—J. K. Y.

[3843]—FLY ROD.—Would "Vivís Sperandum" kindly say how he fitted the eud joints on hi» fly rod, and also where to get wood and all other material» suitable for ваше, as I have long been wishing to make one. I hope this will not pass his notice, as 1 thlrk it will interest more than ono of us.—Recular Subscriber.

[3S44 J-ENTOMOLOGICAL QUERY.—I would feel much obliged to any of your entomological readers, who would describe the larva of Cosmia Iraptzinti; it is said to eat its neighbours if placed in the same box with them, which 1 would avoid if I knew it?—K. N.

[3SI5.]-BOEHM FLUTE-Can any fellow reader oxplnin the mechanism of the Bochm flute, also what are the riug holes ou clarionets ?—Another FlauTist.

(384S.]-NICKEL, OR GT.RM.\N SILVER-Can u iy leader tell tnc what is the composition el (Jetman

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