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Great Britain for March, 1867, Dr. J. Bell Pettigrew, is. Irather think it is somewhat scant, and that every-
FRS, the distinguished Curator of the Museum of the one is his own workman; and, of course, in a foreign
Royal College of Surgeons of Edinburgh, announced country, where there are none but Germans, it may be
the startling discovery that all wings-whether those somewhat dull and dreary. But the Anglo-Saxon
of the insect, bat, or bird-were twisted upon them- blood abounds everywhere, and facts you can get for
selves structurally, and that they twisted and untwisted yourself. I believe the safety and security of these
during their action-that in short they formed mobile lands are everything you can desire. The world is
helices or screws. In June of the same year (1867), Dr. growing, through the influence of science and educa-
Pettigrew, following up his admirable researches, tion, somewhat tired of war, and all peoples and all
read an elaborate memoir "On the Mechanism of languages are finding out that riches, well-being, and
Flight," before the Linnean Society of London,* in comfort are to be found in the pursuit of the peaceful
which he conclusively proves, by a large number of arts of manufacture and agriculture, rather than in
dissections and experiments, in which he greatly the barbarous pastime of war.
excels, that not only is the wing a screw structurally
and physiologically, but further that it is a reciproca-
ting screw. He shows, in fact, that the wing, during
its oscillations, describes a figure of 8 track, similar in
some respects to that described by an oar in sculling.
This holds true of the vibrating wing of the insect,
bat, and bird, when the bodies of these animals are
artificially fixed.

When, however, the creatures are liberated, and flying at a high horizontal speed, the figure of 8, as Le points out, is curiously enough converted into a care track, from the wing being carried forward by the body, and from its consequently never being pernatted to complete more than a single curve of the 8. This is an entirely new view of the structure and functions of the wing, and one fraught with the deepest possible interest to the aeronautical world. It promises to solve everything, Dr. Pettigrew's remarkable discovery has received an unlooked for confirmation within the last few months at the bands of Professor Marey, of the College of France, Paris, This gentleman, who has acquired great celebrity for his improvements and dexterity in the use of the phymograph, has succeeded in causing the wing of The insect and bird to register their own movements, and has established by an actual experimentum crucis. the absolute correctness of Dr. Fettigrew's views. Professor Marey's mode of registering displays much ingenuity, and is briefly as follows:-A cylinder revolving at a given speed is enveloped by a sheet of thin paper smeared with lampblack, and to this the tip of the rapidly-vibrating wing of the insect is applied in such a manner as to cause it to brush out its track on the blackened paper, which it readily does. A similar result is obtained in the bird by fixing a registering apparatus to the wing, and causing the bird to fly in a chamber. In this case the register ing apparatus is connected with the cylinder by means of delicate wires, and the registering is effected by means of electricity. In both cases the figure of 8 and wave movements, originally described and figured by Dr. Pettigrew, are faithfully reproduced. It is difficult to forsee what next. The way of a wing in the air has hitherto been regarded as a physiological puzzle of great magnitude; and well it might be, since some insects (the common fly for example) vibrate their wings at the almost inconceivable speed of 300 strokes per second, that is, 18,000 times in a minute!

SCIENCE FOR THE YOUNG. SIR,-The uncourteous tone of Mr. O'Connor's letter, p. 257, ENGLISH MECHANIC, imperatively forbids my taking any notice of its contents. Nothing would induce me to help on, even ever so little, that spirit of incivility between correspondents in the ENGLISH MECHANIC, which has done so much mischief in 'times' now fortunately passed, to the real, the best interests of the journal. Were this obstacle not in the way, it would be easy to show Mr. O'Connor that a better acquaintance with "Science for the Young" would probably more than reconcile him to the divisions of the subject, and would certainly convince him that there was no reason for his letter.

E. KERNAN, Clon gowes.

EMIGRATION.-TO "COTTON CLERK AND
OTHERS.

SIR-Divert your attention for a moment from Canada and the other British colonies, and direct your thoughts also for a moment to other States, whether as regards Republics, or under other Governments-for example, South America. Not countries which lie within the Tropics, but in those broad, healthy climates which lie to the south of, say, Rio de Janeiro. From this point, lying southward, you come first to Santo Paulo, a district where lately, I believe, there has been introduced a railway, through English capital, and gas works, and a region of great beauty and fertility. Then you come to Paranagua and San Francisco; then to San Catherina and Portalagre, all offering some splendid sites for emigrants, but some, of course, preferable to others. Then you come to the Banda Oriental, the Entre Rios (district lying between the two rivers Uruguay and Parana), and lastly the unsettled but magnificent district of Paraguay, which grows everything almost in the world." All these countries are either Republics, enjoying their own privileges, or are under the Brazilian Government. Το these regions resort, every year, hundreds of Germaus, thrifty and wise, who congregate together and make their own peaceful settlements there, become farmers, and make their little fortunes. The exact settlements where these honest Germans live I do not precisely know; but they have this advantage, they have the country to themselves, and live in peace. I should say to this good and industrious "Cotton Clerk," place yourself at once in correspondence with any house you may know at Liverpool who trades with the Brazils-he will give you all information; or, secondly, with any merchant trading with Bucnos Ayres or Monte Video; or, thirdly, if you know any German at Liverpool, Manchester, or London, he could tell you what his countrymen are doing. Recollect, when you go to a British settlement, you must pay for the fancied security. In the other countries on the Southern Main you may get quantities of land all but given to you that is, in some of the above countries. You can ascertain for yourself what population there

This memoir, which is illustrated by nearly 100 original figures, is published in extenso in the 126th volume of the Transactions of the Society.

COTTON SPINNING.

E. W. J.

The

what draught ought there to be between the 1st and 2nd, 2nd and 3rd, and 3rd and 4th rollers?"

On page 183 E. Slater, Burnley, replies thus: "Let Factory Lad,' page 136, divide his 7 by 3, and make the draughts of each line of rollers in the drawing boxes equal, as 2} + 2 + 2} = 7, or 2} + 2} + 2} = 7." On page 231 Mr. Slater corrects himself in the following words: "My meaning was (from front to back), between front and 2nd roller, 25; between 2nd and 3rd, 169; between 3rd and 4th, 167. Or, reversing their order, 167 x 169 × 25 = 705575, or something as near this order as he should find convenient. I was once rarely puzzled by a similar answer, given to me by a very intelligent old man; however, I learnt something from it, and if you think you will do the same."

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Now, I submit that if Mr. Slater will think, he must think that it would tend more to the improvement of our contributors if he would kindly write what he means at once; for I dare be bound he is the only person who reads his two replies who will find the least He says his possible resemblance between them. object in writing is to set us thinking. It certainly will; but it leads me to think he ought to be a little more consistent, "especially when, as in this case, the subject is a very important one." MUTUAL IMPROVEMENT,

SIR,-Your correspondent, "B. W. R.," page 230, seems very much disposed to carry out the old adage -viz., to pick a fellah up before he's down "-with respect to my letter on draughts. When will ye have wisdom, and hearken to the voice of reason, O ye cotton lords! Surely "B. W. R." must have penetrated very deep into the mysteries of the fibrous art to find out that a lap will bag if there is no draught between feed and lap rollers. Let me inform him, for bis edification, that we have at the present time about 140 carding engines at work, and if he can find the slightest draught in any one of them, or the least sign of a SIR-Edward Habergham, p. 204, says he is wishful to understand the backing off motion, and the operation of the cam shaft. The term "backing off" is slack lap, I dare forfeit the engine he finds it in. same may be said with respect to the lap rollers of our applied to the reversed motion of mule spindles at the combing machines. It may not be out of place here finish of a "spinning stretch," by which the coil of yarn to remark that I flatter myself with having penetrated that the spinning action has thrown upon the bare so far in the art of cotton spinning to know that if the lap rollers move at the same surface speed as the feed portion of them is unwound down to the point of the is the draught (!) of our engines between lap and feed action must take place at the same time, and correrollers, it is impossible for the lap to bag. The following cop, so that the action of winding may commence on Now, observe, this backing off the body of the cop. rollers:-Diam. feed rollers, 1in.; lap rollers, 6in.;spond in its speed to the downward motion of the a 14 wheel on end of feed roller drives a 48 on end faller; for if the spindles back off quicker than the of lap roller. The result of the above, when well reckoned, will amount to about as much as "B. W. R.'s" faller goes down, the yarn will be thrown off into "snarles;" or, if slower, it will be overstretched, and the penetration does, I want to know what use a draught bottom coils pushed down in a slovenly manner to the cop shoulder. And, moreover, as the cop is continually would be if the lap is delivered just as the feed rollers take it? How can it bag? You just may as well say increasing in length, the backing off must be dimi that the break van at the rear end of a train will get nished in the same proportion. From this, then, it is into the station before the engine that is pulling it. B. W. R." also refers me to a letter of E. Slater, on clear that the two distinct operations, the locking of the faller and the backing off of the yarn, must by is a draught. Certainly E. Slater may have a draught This has been ingeniously accomplished by many dif the same page as my own, to convince me that there some means be made to depend upon each other. in his engines; but if E. Slater has a failing (which it ferent arrangements of levers and cams, &c.; so I will certainly is), it does not follow that it must be crammed now try to explain their action and principle. See the into every person's noddle, whether they agree with it sketch, which, I may observe, is not intended to be a correct representation of any working mule, but to or not. By-the-bye, if all E. Slater's contributions are to be judged from his distribution of "Factory Lad's" illustrate the actions, and help to convey some idea of draughts, and his "penny wise and pound foolish" the cam shaft and backing off motion. 1 is the backing ideas about draw-boxes; if we are to infer that these off dise or cup, to which a retarded motion is given are the truth, and nothing but the truth," then I from the pulley 3 by the wheels 4, 5, 6, 7, and 8, and must say that "B. W. R.'s" "penetration has not this in an opposite direction to that of the pulley 2 The pulley 3 is loose upon the rim shaft, been of much use to himself, or he would never have and rim. referred me to E. Slater to be convinced of my error (?). and connected to the wheel 4 by a long boss. 10 is the "B. W. R." also loses his extraordinary "penetra-ordinary loose pulley. Fast upon the rim shaft is the ting" powers when he states that the draw-box of a friction cone 11. The surface of this corresponds to carding-engine is between the doffer and delivery the inside of the cup 1. Let us now suppose that a rollers. He must mean between the doffer and coiler stretch has been spun, and that there is some kind of rollers, as the draw-box and the delivery rollers are a bracket fixed to the carriage, which comes in contact the same thing-at least they are so called in this with the long lever, and causes it to fall a certain disquarter of the globe. What I said then I say now, tance at the front end. This action of the lever will that there is not any draught between doffer and delicause a corresponding rise of the connecting rod a, very rollers-i. e., tlie draw-box. which in its turn will lift up an escape lever, b, that has been holding against one of the pallets, c, on the end of the cam shaft, A. As soon as this takes place, the cam shaft having power given to it either by a friction bowl, a strap, or other means, turns round until another of the pallets comes in contact with it has, by means of cams that are attached to it, the escape lever. But suppose this first movement of caused the strap to be thrown on to the pulley 3, and the disc 1 to be pressed against the cone 11 by the lever b, it is evident that the disc will not only act as a brake to the rim shaft and spindles, but when it has stopped their motion in one direction it will then turn them in its own, or reverse their first direction, and that this action will go on as long as the cam D presses the disc against the cone, or so long as the cam shaft However, as soon as the rim keeps this condition. begins to move in a backward direction, the catch

33

THE HARMONIOUS COTTON SPINNER.
[Some of our cotton correspondents are somewhat
inclined to "chaff" each other. This is no doubt amusing
to them, but they should remember it occupies valu-
able space which might be better appropriated. They
and all others would oblige by telling us what they
have to say in the fewest number of words, so that
we may be enabled to give the largest amount of infor-
mation for the largest number of readers.-ED. E. M.]

SIR, CONTRIVANCES FOR TESTING THE STRENGTH OF YARNS, &C.-I shall be very much obliged if any of the Cotton Spinning Company will give me some information about the above. The reason of me troubling you is this: I have an idea of making a simple machine by which you can tell comes in contact with the teeth of the ratchet wheel the strength of yarns in lbs. and oz. without the aid of springs, or any complicated mechanism, which is fixed upon the same shaft as the pulley 12, The ratchet then causes the ring at all about it. What I require is this a brief or spindle shaft. explanation (accompanied by diagrams if found to turn round along with the shaft and spindles; and needful) of the most complete and simple contrivances as the chain 13 is attached to this ring, the motion is now in use, that will give the strength of yarns from commnnicated by this means to the "faller sector" 14, SO single, down to 40 12 fold heald yarn. If I find which is pulled down at a speed corresponding to that that there are more simple and correct ones than at which the yarn is being unwound, until the latch mine (which I am not so self confident as to doubt at 15 falls at the end of the sector, and locks the faller. all), then of course I shall not go on with mine; but The falling of the latch 15 allows the lever 16 to fall if I see that mine will have any advantage over the also, and this, through the rod 17, allows the long lever to fall another distance, which in its turn again others in use, then I shall get one finished, and trouble you to give a description of it with a sketch, so that I liberates the cam shaft from the contact of escape can submit it to the penetration of your now numerous lever and pallet. The cam shaft now turns a distance body of cotton spinning subscribers. I shall be glad further, and throws back the disc to its loose position when anybody replies to the above, if they will give upon rim shaft, and, at the same time, by other cams and levers, throws the putting up wheels into gear, the names of the makers, and where I can obtain one. I beg to return my thanks to Joseph B. Crossley (p. and the carriage runs up until the long lever is pressed 254) for his recipe for size for cop bottoms, which I down again at the back end, and the cam again is find to act very well, especially with a bit of fish allowed to complete its revolution, throwing spindles, glue added to it. He is right in saying that the dif- rollers, and carriage into gear all at once for another ference in the make of frames will make the results of experiments very considerably, but I cannot understand (except from that cause) how he can run his frames faster with the bobbins leading than with the flyers leading. Of course there is not much difference when the bobbins are full, and they are leading, and you are making about a 12 bank roving, but when the frames are just starting a fresh set, and the bobbins are empty, and you are making say bank slubbing, then is the time the poor tubes "get it hot." I have not very much spare time at present (and probably you have not much spare room) or I would go into this much-neglected subject more fully. Early informati on on the yarn testing subject will greatly oblige.

THE HARMONIOUS COTTON SPINNER.

SIR-DRAUGHT OF DRAWING FRAME-On page 136" Factory Lad" asks: "Suppose a drawing frame to have 4 lines of rollers, with a total draught of 7,

stretch.

I may observe that the first motion of the cam shaft at the finish of the out stretch of the carriage is often made to throw the rollers and carriage out of gear, whilst the strap is still allowed to drive on the rim

pulley for the purpose of putting extra twist in the yarn. When this is the case, the cam shaft will be held stationary by some such_arrangement as a worm that the less the cops are, the higher is the builder, and bell wheel would give. It is well to observe also,

which causes the latch 15 to be thrown farther back on the surface of the sector 14; and the farther back this is thrown, the longer will the spindles back off before The arrangement of wheels, cams, levers, &c., that the cam shaft is liberated by the falling of the latch. have beer contrived to produce these various conditions and motions to such a degree of perfection as we now find them, has required a great amount of ingenuity; and to understand their working thoroughly will be well worth the trouble Edward Habergham may devote to the purpose. In fact, the self-acting

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E. SLATER, Burnley.

A CLIP FOR HOLDING PAPERS.
SIR,-I beg to send a drawing of a simple
contrivance for holding blotting paper, or letters,

SIMULTANEOUS EQUATIONS.

SIR, I venture to hope I did not in the least way hurt the feelings of my dear brother correspondent

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"C. H. W. B." I beg to assure him this was not at all my intention. Of course, if Mr. Todhunter gives these problems only as exercise of the 2nd degree two solutions are sufficient. I believe that several author give the problems of the form " + p + q = 0, in which the exponent of r in the first term is double of that in the second, and which can be solved by the 2nd degree only to exercise the pupils in algebraical practice. The valuable German treatise of E. Heis, Just lying before me, gives also a collection of them. Several problems of Mr. E. H. have been translated into English in the "1000 Algebraical Tests," by Mr. T. H. Cayzer, London, 1861.

BERNARDIN.

EXTRACTS FROM CORRESPONDENCE.

AN ENGLISH MECHANICS' SOCIETY FOR LONDON.-"G. G. B." writes:-" How is it that the metropolis is behind the provinces in the establishment of a mechanical association? Certainly there must be numbers of suitable men in and about London to form a first-class society. Will a few favourably. disposed gentlemen, with scientific and mechanical inclination and ability, send me their names and addresses, with a view to holding a preliminary meeting? I should like to invite, by their noms de plume, many of your able correspondents, but it would be invidious to do so; besides, unless the desire is mutual and spontaneous, the affair would be weak and insipid. I shall be happy to receive any response to this, either through our MECHANIC or by post, addressed to G. G. B., Ripon Lodge, Grove Park, Camberwell."

VELOCIPEDES.-"Isle of Ely" says:-"I think my brother readers are rather hard on Mr. H. W. Reveley. The 30 miles per hour I cannot believe in. but still he has hit the right nail on the head, for a slow motion of the legs, and a quick motion of the wheels, are just the things required in a veloce. We have another tempting bait in 'Leo's' veloce, now this has been tried, and he states it will run at the rate of 15 miles per hour. If this be true (but I am inclined to doubt it), no crank velocipede can come up to it. He would greatly oblige us by giving a clearer description. Has any other reader seen this machine? I have tried many different kinds of velocipedes, but never one of a swinging motion. It seems to me you cannot get the power with them you can with others. What is the width between the swinging bars of the back wheel bicycle? I cannot see how the steering wheel is kept from coming against them in turning a corner."

CLAIRVOYANCE.-" Solicitor" says:"Perhaps the following case may interest our friends 'Sigma' and Harmonious Blacksmith. Some years ago a relative of mine arrived at home unexpectedly one evening from Buenos Ayres, the door was opened to him by one of his brothers, and almost one of the first questions asked by the absentee was, 'Is your wife living? The reply was in the negative, calling forth the exclamation, Ah, I feared as much, I saw her on board our ship on the evening of -- -(I forget the exact date). I may say the date was the day of the lady's death.""

DISTANCE OF THE SUN, &c.-" Hugo" writes:Allow me to tell Veritas' that angles are not proportional to their tangents, as he seems to think; and, therefore, it is not true that 'the mean distance of the sun is to the mean distance of Venus from the earth as the mean horizontal parallax of Venus is to the mean horizontal parallax of the sun.'

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339

"AB INITIO" CORRECTED.-J. Dyer" says:"I am at a loss to understand Ab Initio. He says, Philadelphia, for instance, has its time 5 hours earlier than London, it being only 7 a.m. there when it is noon here.' If the rotation of the earth was from east to west this would be the case, but as it turns in the opposite direction, looking south, any place west of London, as Philadelphia, must have its time later, or after Loudon time. How noon can be after 7 in the morning of the same day, or how the time of a place with the sun on its meridian can be later than another 75 deg., or 5 hours to the west of it, I know not. If the time of Philadelphia in 5 hours earlier than London time, then the time at London is 2 hours earlier than the time at St. Petersburg, and When Wednesday of the same week is, in point of time, earlier than Tuesday, then will this be, but not before."

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least I never could drive too fast for a good result. Fig. 1 is
a front view; Fig. 2 perspective view; Fig. 3 shows elevation
of a cutter for threads of high pitch ground away to clear
under the cutting edge. Also plan view of a thin and a
thick cutter for 2 different pitches. This tool is more expen-
sive, and not so good as mine.-J. K. P.

[2538.]-INCRUSTATION IN POROUS CELLS.-The
querist asks a means for preventing the incrustation of the
cells of his battery; the following arrangement may, I
believe, suit him. I imagined this battery some weeks ago,
and one is working now since 16 days with the greatest
regularity, serving several clocks, and having nearly no
incrustation at all. I put in the jar ordinary water and a
zinc plate, and in the cell a mixture of water and 1-25th
part of sulphuric acid and a small plate of copper; and am,
as far as yet, quite satisfied with the results.-D. N. OMIAR,
Belgium.

[2558.)-SUN DIAL-I was much struck by the very
simple method described by your correspondent "Anon," in
your impression of May 6, 1870, of obtaining a true meridian
line-viz.. by the "ordnance maps" and "railway time," and
began to doubt the old-fashioned method, which I have
always adopted when I desired to ascertain my meridian, as
determined by equal altitudes on a horizontal plane by a per-
pendicular style in the centre of concentric circles, which
requires neither ordnance maps, railway time, nor setting a
watch by a dial, involving equation of time, &c., but only a
clear, sunshiny day, or intervals of sunshine, at periods of
equal altitudes. This method is so simple, so often quoted.
and is found in so large a number of works rest I should
imagine that every reader of the ENGLISH MECHANIC w
be acquainted with it. When once a true meridian line is
obtained, and permanently marked, it is very useful for a
variety of purposes, setting a sun dial included.
I have one
in my garden consisting of a stretched wire about 10ft. long,
which is attached to a tall stake truly upright, and which
passes to the centre of the south pier of my telescope. When
the shadow of the west edge of the stake coincides with
the shadow of the wire, both being received upon a stone
povement, the sun transits the meridian. I find this exceed-
ingly useful for obtaining apparent time at noon.-W. R.
BIRT, Cynthia Villa Observatory, Walthamstow.

[3675.]-NAVAL ARCHITECTURE-In answer to some
correspondent who asked a question on this subject about
two weeks ago, I am able to state that there are not, and
never have been, any evening classes at South Kensington,
for the purpose of teaching the above. There is in the South
Kensington Museum the "Royal School of Naval Arehitec-
ture and Marine Engineering," in which both these subjects
are taught. Very full information concerning it may be
obtained by writing to the Secretary, Science and Art Depart-
ment, South Kensington Museum.-F. W. G.

[3707.]-TWISTING POWER OF METAL.-Molesworth's "Pocket Book" gives the following table of the "relative powers of metals to resist torsion -Wrought iron, 100: cast do., 90; cast steel, 193-STEERSMAN.

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[3746.]-TESTING BOILER-Having opened the flues so that a thorough inspection of the outside of the boiler may be easily made, run the boiler full of water, and get an ordinary boiler maker's force-pump, which may generally be obtained on hire from any boiler maker or dealer in machinery. Having connected the pump to the boiler by means of the feed-pipe or otherwise, close all other orifices except the one leading to the pressure gauge. When the finger (if a Bourdon) or mercury points to the required pressure, let your man make a careful examination of the whole boiler. It were best that a boiler-maker or engineer should perform this duty, as he would be able to remedy any defect; and if there be no sign of leakage you might work safely under steam to one-fourth the indicated cold pressure. Thus, supposing the boiler so POTATO REFORM.-In a little tract called "Po- found to be in good condition, and you prove it to 1201b. tato Culture," Mr. F. W. Wilkins points out to us a you might work up to 301b. under steam, but do not trust to method of generally increasing our potato yield, which your own idea of its state, as there might be some defect is worthy of the most careful trial; for, if his experi- which would escape your attention, but catch the eye of an ments are correct, he has put us in the way of quad-experienced man at once.-T. S. CONISBEE. rupling the crop of this most useful vegetable. At present, potatoes are planted in rows, about 2ft. apart, and 10 or 12in. from each other, the average prodnce being 240 bushels to the acre, or 6 tons, worth (say, at 38. per bushel) about £36 per acre. By the new method, large whole potatoes are selected, and the eyes, all but one or two, scooped out. They are then planted 4in. deep, in rows 4ft., or, if very large, 51t. apart. The result is, that each plant produces from halt a busbel to one bushel, the potatoes themselves weighing 2lbs., 3lbs., 4lbs., or eveu 6lbs. The yield of the acre therefore is 1360 bushels, instead of 240, and the acre will bring in to the fortunate owner £204 instead of £36, The rationa e of the proceedings seems to be, that we dwarf and stunt our potatoes by overcrowding, like we do our children in towns, and that the proper mode of treatment is to give to each potato sufficirut room to expand, regarding it, in fact, like a young tree. The plants, indeed, grow to such a size that they are obliged to be supported by pea-sticks, to which they must be tied like hops to poles. We most strongly recommend a trial of this new form of potato culture to our gardening readers.

[3755.]-TURBINE WHEEL-" A. B," will by this reply see the rationale) of my request to be supplied with some data. A 1-horse power turbine with a 20ft. head of water would require 35 cubic feet per minute. His in. pipe would supply only 0-304 cubic feet, the loss in friction with such a small feed being enormous and quite useless for any practical purpose. There is no special line of demarcation between that which is a high or low pressure turbine. I should call any turbine with a head of water of from 7 to 14ft. low pressure. The writer knows of a very powerful tarbine working with only 9in. of head, and he has erected several up to 14ft., and one with a head of 260ft., with a supply of only 200 cubic feet per minute, which gave an indicated power of over 60 h. p.-SENEX.

[3786.] AREA OF SAFETY VALVES AND PISTONS'I note a remark by "Mutual Improvement," p. 260, as to corrugated pistons. Perbaps he is not aware that not only has that very thing been done, but it is patented. I once had a het argument with a somewhat eminent engineer who believed in the notion, while I contended, of course, that though the surface was increased, and with it the pressure, still, as the increased pressure was not in the direction of the motion, there was no gain, and the effective work is only due

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[3839.]-COLOURING TRACING PAPER-A little oxgall mixed with the pigments will make them flow readily on the cloth or paper, and "Tracing should paint on the under side of his drawings so as to show through the cloth.SOLICITOR.

[3843.-FLY ROD.-In reply to "Regular Subscriber,' the joints of my rods are all tongue and socket joints, being in my opinion the best. The ferrule is fitted upon the joint for of its length, let in the thickness of the brass. The socket is bored with a slight taper first with a spoon bit, and finished with a taper round file. The tongue is made to fit tight of its length, allowing for slackness, occasioned by wear. The ferrule should not be made fast until the boring and fitting are satisfactorily done, as it has to be taken off now and then to see if the hole is straight and smooth; always keep it ou, however, when boring or fitting the tongue in, else the wood will split. Next, paint the joint with whitelead, drive the ferrule well home, and fasten with two brass pins at right angles to each other, one from the base of brass, and one an inch from the same. The ash I get on my own property-it is better to be cut from a tree, and not more than 9" diameter. The outside is the best, and it must be reedy, and free from gnarls or cross grains, and very well seasoned before using. The hickory, or lancewood, I pick up where I can, generally getting what I waat in a coach factory or scantling yard. I stain my rods with logwood and alum

which gives a dark plum colour; never stain with an acid, as it generally destroys the wood, burning all the juices of the timber right out, and rendering it what is technically called "frush." The lapping is done with strong saddlers' twist silk, well waxed, and the whole varnished with coachmakers' varnish. The butt end of rod may have either a spike attached, or finished off with a piece of horn or brass ferrule. Any further information will be given cheerfully, free, gratis, for nothing. I send a sketch of joint.-VIVIS SPERANDUM.

[3851]-TO CLEAN SADDLES.-Wash with yellow soap, and dress with the smallest possible quantity of neatsfoot oil. When the oil is dried in, use beeswax dissolved in turpentine, apply with a brush, and polish with a soft cloth.-A NEW

SUBSCRIBER.

[3852.]-BRASS INSTRUMENTS.- The bends in brass musical instruments are made by filling the straight tube with lead or pitch, and after the correct curve is obtained the substance is melted out.-SOLICITOR.

The

[3856.]-TRICYCLE.-"W. B." will find 4ft. 6in. wheels worse than useless for any kind of velocipede whatever. Velocipede wheels should never exceed 3ft for ordinary roads. Never forget small wheels and long cranks for ease. following. I think, would be the best tricycle for two on a long journey; although bad to turn round, it will easily turn out of the way. The front wheel just the same as a bicycle front wheel; the two hind wheels, of course, with a two-crank axle; all the cranks one size-say Sin.; all the cranks connected by two ash treadles. Both men would step alike; the treadles would have long eyes on the front cranks, to allow for a little turning out of the way. The foot is not required to press flat on the treadles, but the same as if in a stirrup, so that the foot is always in a straight and easy position. The hind man would require a hand hold on each side, so that he could press well with his feet. Hand levers would not be required. A better velocipede for two on a long journey cannot be made; two hind wheels 26in. apart-not more.ANDREW JOHNSON.

[3864.]-EXTRACT OF DANDELION-"Sable " sends a "Poor Blacksmith" what he asks for from the Pharmacopæia, it is the article of commerce:-Take of fresh dandelion root (bruised) 241b., boiling distilled water 2 galls.; macerate for 24 hours, then boil down to 1 gal..strain while hot, and evaporate to a proper consistence.-SABLE.

[3868.]-WATERPROOFING CLOTH.-"A. S. A." asks for a recipe for waterproofing cloth. Though my answer is probably not quite what he wants, yet it may help others. 1 tried it as an experiment, and found it to be a waterproof, though that was not my design in doing it. I wanted to fasten two thicknesses of black calico together for a photographic tent, so I laid a sheet of thin gutta percha, procurable at any chemist's, between the two pieces of calico, and then ironed it with flat-iron as hot as I dare use. The cohesion was perfect; it was a waterproof and light-proof too, and very easily made.-COUNTRY PARSON.

[3869.]-WATERPROOFING CLOTH.-1b. of sugar of lead, 1lb. of alum, pound separately, and mix in a basin, and then pour 2qts. of boiling water on the mixture; let it stand 6 hours, and then bottle off for use. Apply to the cloth with a sponge or soft brush on a table till well saturated, and then iron it over and hang up to dry.-(From the Field.)-A NEW SUBSCRIBER.

63882.]-STEAM AND WATER.-The two motive powers of steam and water can be applied to the same shaft. As water is the cheapest mode of driving, of course it is used to its fullest extent first, and what is wanted to be gained in speed or power is added by the engine, a competent engineer being always able to tell whether the wheel is driving the engine, or vice versa.

In all cases where a wheel and engine are in connection, they should both be started at one time, the wheel driving and the engine gradually brought up to the required speed by the engineer at the valve.-VIVIS SPERANDUM.

[3883.1-MANUFACTURE OF OXYGEN-See G. E. Davis's letter.

[3886.]-WA1ER ANALYSIS.-See G. E. Davis's letter. [3894.] IRISH RING MONEY. I beg to refer "Daukosen" to a paper read before the Royal Academy by Sir William Betham, M.R.I.A., Ulster, King of Arms, printed at Dublin, in 1836. I would give the quotations, but they are too long. He attributes the date of them to be several centuries before the Christian Era, and used by the Phonicians in barter, to whom he assigns the invention. He says, "Cæsarells us that the Gauls use for money gold and iron

rings, by certain weight." The latter have perished by oxidation, but the two former are found in great abundance in There are the fields and bogs in every part of Ireland." ma ny varieties engraved illustrating the paper above alluded to, but none like the one in the ENGLISH MECHANIC. Perhaps the usual flat or cup terminations may be seen broken off.D. T. BATTY, 9, Fennell-street, Manchester.

[3891.] SLIDE VALVE.-I should not think that "Slide Valve" would succeed with an engine having a cylinder less than 3in. stroke, or 1in bore. The flywheel would require to be about 10in. diameter. I shall be happy to give him any further particulars.-IXION.

[3594]-IRISH RING MONEY-In answer to "Daukosen," I beg to inform him that it was used by the ancient Celtic inhabitants of Ireland. They are usually in the shape of a crescent, sometimes with and sometimes without pointed ends. The weights of some are 53gr., 1dwt. 2gr., and 4dwt. One, in the shape of a horse-shoe, weighed as much as 15dwt. "Daukosen" is mistaken in supposing that they may have formed links of gold chains; they are always alone, and complete in themselves. They must have been current money, and not ornaments, because they exhibit no signs of attrition in places where they could have been worn. They are, I believe, always made of the purest gold. Very little is known of these curious articles, but there is a short paper on them, with three illustratious, in the Numismatic Chronicle, old series, vol. vii. It is by Edward Hoare, Esq., of Cork. From it I quote the following: A friend has suggested to me, and I think with great probability of truth, that it is possible that the crescentic form has been given to these Celtic rings with a religious protective view. The worship of the moon is an idolatry of the most ancient date, and the crescent form may have been adopted to preserve by its sacred character, the circulating medium from spoliation or debasement, in like manner as the ancient Greeks impressed the images of their gods upon their coins, as it is believed by many, in order to vouch for their purity and weight, and to secure them from damage.-HENRY W. HENFREY, M.N. S., &c. [3830.]-THERMOMETER-If "Thermometer "will take Ais instrument by the end furthest from the bulb, and give it a good shake by swinging his arm, he will probably find all the mercury unite.-IXION.

[8895.]-PARASITES ON CANARIES.-To cleanse the bird, tie a piece of unslaked lime about twice the size of a walnut in a piece of coarse calico exactly as a woman makes a blue-bag, leaving ends to it; dip it in water, and put it on the bottom of the cage. As the birds fly about, the fumes from the lime as it slakes penetrates between the feathers, and cause the lice to drop from the bird. Keep the bag in about a week; it will not hurt the birds. To clear the cages, &c., make a strong solution of alum and water, wash the whole with it; this will kill the lice dead as stones, and is far better than lime-washing. The breeding-hoxes can be dropped inte a pail containing alum solution for a few minutes, and then hung up wet as they are; it will not hurt the birds. Special attention should be paid to the moss, seed, and egg pans, as it is under these that the insects breed in the greatest numbers. This process can be repeated as often as heerssary, and it is better to have a spare cage to put the birds in while cleaning their own, if they are breeding. By paying attention to this the birds can be kept free from the pest.-A NEW SUBSCRIBER.

[3895,]-CANARIES.-The disease with which your canary is afflicted is a troublesome one, and if the cage is infested with vermin it is best not to use it again. Those parts of the bird where the vermin are most likely to lurk should first be syringed with water in which a little quicksilver has been allowed to remain for some hours, or with a weak infusion of tobacco. Some recommend fumigation with this herb, but the inhalation of it by the bird, which can hardly be prevented, must prove prejudicial. Frequent bathing, great attention to cleanliness both as regards the cage and its inmate, and a daily supply of fresh sand, are also necessary to effect the ejectment of these troublesome visitors. A cage of which they have once taken possession is, however, never entirely freed from them; and it is best to get rid of it. If you cannot do this, wash it often, sprinkle the joints and crevices with turpentine or a weak solution of white precipi tate powder, taking care not to put the birds into it for some With this solution also, hours after the operation is done. should the vermin prove obstinate, the body of the bird may be washed at those parts which it cannot reach with its beak. -A LOVER OF BIRDS.

[3895.]-PARASITES ON CANARIES.-Some years ago I found that my birds were infested with these pests, and wasting flesh as though they had some disease. I tried several washes and powders, but found none so good as the following:-Well soak the cages in water to loosen the dirt, then carefully scrub them inside and out, dry them, and drop a little paraffin oil into all the cracks and crevices. If there are any in the bird, hang a white cloth over the cage at night, and they will soon leave the cage for the cloth, when they may be shaken off in the morning.-J. H. P.

[3896.]-LADDER PROBLEM.-I note that "Ignoramus" has not given the height of the man who has to go up the ladder for his head to be level with spout; for a man 5ft. 6in high, it would take a ladder 32ft. long; height where resting against wall, 21ft. from ground. For a man 6ft. high, it would take a ladder 31ft. fin.; height from ground where resting against wall, 20ft. 4in.-J. PARKER, Swindon,

[3909.]-COPPER COIN.-No. 1 is a third brass, of Constantine the Great. The full legend on obv. is VRBS ROMA. The rev. represents the tradition of Romulus and Remus, founders of Rome, suckled by a wolf, the letters T. R. P. in the exergue signifying, I think, Treveris Pecunia. No. 2 is not defined sufficiently for me to make out.-D. T. BATTY, 9, Fennell-street, Manchester.

3911]-GALVANIC CELL-"Hermit's" galvanic cell is the same as Bunsen's, and he should therefore use strong nitric acid for the porous cell, and a mixture of about 12 parts by measure of sulphuric acid to 100 parts water for the outer compartment. As the mixture last mentioned gives out great heat on mingling, it should not be prepared in a glass vessel. The cell will give good intensity but moderate constancy.T. S. CONISBEE.

[3911]-GALVANIC CELL-In answer to "Hermit," two exciting fluids are required-one for the carbon and the other for the zinc. That for the carbon is undiluted nitric acid (aqua fortis), and for the zinc diluted sulphuric acid (1 part by measure of the acid to 7 parts of water.) This battery (Bunsen's carbon) is very effective in use, and involves a current of considerable intensity-ELECTRIC.

(3920.] MEASURING LIVE STOCK. TO "A COUNTRYMAN."-Measure round the animal close behind the shoulder, then along the back from the fore part of the

shoulder blade to the bone at the tail. Multiply the square of the girth by 5 times the length, both expressed in feet; divide the result by 21, and you have the weight of the 4 quarters in stones of 14lb. Thus, if the girth be 6ft., multiply by G. that gives 42ft.; then if the length he 5ft, multiply by 5. making 26 ft.; next multiply the result 42 by 261, and you

1

have 1109-ft.; this divided by 21 gives 52st. 11lb. as nearly 16

as possible.-M. P. C. S.

[3920.]-MEASURING LIVE STOCK-Among a host of memoranda I had the following rule, which may be of service to "A Countryman." Measure the girt close behind the shoulder, and the length from the fore-purt of the shoulderblade along the back to the bone at the tail, which is in a vertical line with the buttock, both in feet. Multiply the square of the girt, expressed in feet, by 5 times the length, and divide the product by 21; the quotient is the weight nearly of the 4 quarters in imperial stones of 141b. avoirdapoise. For example, if the girt be 6ft. and the length 5ft., we shall have 6 x 6 = 421, and 51 × 5 = 26}; then 1

16

4

5

42 × 261 = 1109, and this divided by 21 gives 52stones nearly. It is to be observed, however, that in very fat cattle the 4 quarters will be about 1-20th more, while in those in a very lean state they will be 1-20th less than the weight observed by the rule. The 4 quarters are httle more than one-half the weight of the living animal; the skin weighing about the 18th part, and the tallow about a 12th part of the whole-HARRY G. NEWTON.

["Patience and Perseverance" has sent a similar reply.] [3922.)-REMOVING PAINT.-"House Painter" can obtain at almost any oilman's caustic paste, which is sold for the above purpose, but in my opinion burning off the old paint is the only safe method. If any solution be applied to destroy it, the wood will absorb sufficient to materially affect any coating afterwards laid on, and so render the result anything but satisfactory.-HARRY G. NEWTON, [3927.1-WINDOW-PAINTING.-Let "Sable" take of flux, which is formed thus-Glass of lead 11b., of pearl-ashes 60z., of common salt 2oz. The glass of lead being reduced to a fine powder, and intimately combined with the other ingredients, the whole must be put into a crucible capable of retaining vitrified bodies, and fused. The lower the heat by which the fusion can be accomplished the better; the operation should not, therefore, be hurried. When the mixture has become transparent and free from air-bubbles, it may be poured out upon a clean iron plate. If the composition, when cold, is observed to be very foul, it should be reduced to powder, and re-melted, but if only a few foul specks are The good part may then observed, they may be picked out. be reduced to powder and kept for use. This flux is moderately soft, and has a slight tinge of yellow. The glass of lead is prepared by fusing 2 parts of red lead with 1 part of flints calcined, and finely levigated, or instead of flints the finest white siliceous sand. Take of the above flux 6 parts of gold precipitated by tin 1 part; when these ingredients are The colour thus thoroughly mixed they are ready for use. prepared produces a fine crimson, inclining to purple; its strength may be increased by adding more of the oxide of gold. For the yellow, take of the above flux 6 parts, of calcined silver 2 parts, and of antimony part. Vitrify them, and then levigate them for use. The colour is a deep bright yellow proper for shades; where great transparency is wanted the antimony may be omitted. The silver is prepared by covering thin plates of silver with sulphur, and exposing them to a red heat. If sulphate of iron be dissolved in water and precipitated by pearl-ash, this precipitate, used instead of antimony, will produce a very cool and true yellow, proper forming greens with blue.-D. F. ASHTON.

[3931.]-INDIA RUBBER SOLUTION.-It may be made with various solvents-turpentine, chloroform, benzole, &c.; but the best is, I believe, a mixture of 6 parts alcohol (absolute, not mere spirits of wine) with 100 of sulphate of carbon; the latter is the real solvent, the alcohol has an indirect action. The quantity of solvent required depends on the consistency of solution required; if heat (moderate) is used, and the mixture shaken, the whole dissolves, bat a better solution is obtained for adhesive properties by using a large quantity of solvent, not shaking, but drawing off only the clear glazy liquid.-SIGMA.

[3931]-SILK SOLVENTS.-Several substances dissolve silk, such as the ammoniacal solution of oxide of nickel; that

of copper also dissolves silk as well as cotton: the silk is precipitated by acids.

Chloride of zinc saturated with zinc

oxide also dissolves silk, but in no case can silk thread be tion of course involves the destruction of the mechanical dissolved without the "thread being decomposed," for solu

constitution.-SIGMA.

th: Spanish Catalogue of the Paris Exhibition, the name given to the tree by the Spaniards of Manilla. More part.colars, ride "Seeman's Popular History of the Palms,” and many other works. The coarse chocolate-coloured fibres used for making the brooms for sweeping the streets, tir decks of ships, &c., and also employed for With worth sweeping machines, come from the Piacaba palm, Attalea funiform, sed are imported in England from Bahia; a finer sort coneg from Para is produced by another palm tree. Leghor Piacaba, which I find in an horticultural catalogne, Leopoldina Piacaba vera," the Attalea funijera "beng an known by gardeners as Leopoldisa piacaba. The introd of Pará pracaba into industry was an example mon ame application of a simple observation. a bundle have 2 made up at Pará for a vessel, to let down of the balreis ** "fender," to prevent collision, &c. The ship arming L Liverpool the bundle was thrown upon the quay; aramaker took it and made a few brushes from it; they w found to answer well; a small quantity more was imparted, and the trade began. It was formerly imported as "das nage," but orders having increased, piacaba is now imported from Bahia and Pará on freight. A price current I have before me quotes Bahia fibre 12s., and Pará do. 65s, per cet. The nuts of the Altalen funifera, or "Coquilla pats used for turner's work.-BERNARDIN.

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[8954] SCREWING LATHE. If P. N. Hasluc lives near London he had better get my address from the Editor, and come and see my lathe, from which he may g hint or two worth having. 1. The length and breadshe mentions will do. 2. A screw such as I have just made my

5 lathe-viz. diam.. double V thread, pitch, will set, I have in now a screw of 10 to an Lach, and this is to take i'a place. I should not be inside, as it is sure to get dirte wherever it is, and is much easier to clean if outside, and hence likelier to get kept clean. 3. A nose of Whitworth's 4. Geared lathes are generalig thread will do very well. made 2 pair of wheels or pinions of 3 to 1, giving a reduction of speed to 1-9th; this I think much too great for a smaid lathe, and I have made, or had made, several, and am now making a 5 for my own use, with wheels of 3 to 1 in front of pulley, and 2 to 1 behind the pulley, giving I have by me a set for a reduction to 1-6th of speed. 4in. lathe of 2 to 1, and 2 to 1, or a reduction of 4. Th numbers suitable are 72 and 24 for the front, and and 82 behind, both of the same size of teeth which in my case is to be nearly No. 9 on the Manchester guage, giving the 72 wheel 8 diam. by thick, and the other pair only thick as the strain on them is less. The teeth are to be cut in gun-metal. If you have cast wheels 60 and 20 on the No. 8 guage give distance of centres of mandrels 3in., and a pulley of 71, which you will hardly get into a 4 head, and the 10 guage gives a 6in. pulley, which is too small. Perhaps Lloyd may have gear wheels specially for 4 lathe by him. Mine are 66 and 33 on the 10 guage, and are in Lloyd's hands, 5. I should not advise selfwith liberty to cast from them. acting surfacing, which I do with a band from overhead. I should make the bottom slide project over the rear side of bed 2 or 3in. in addition to the ordinary length The last I made was a fone, and the bottom slide measured 102, and I was sorry I had not made it 12"before I had done it. The top one may The best tool holder swivels round on run 4in. more or less. a centre bolt, and is of square shape supported under two of the corners by a couple of pillars, and has set screws attached tapped down through the other two corners, which are provided with bosses for the purpose. 6. You cannot wish for a better wheel cutter than mine figured in No. 215 of the ENGLISH MECHANIC. If you use a dividing-plate with holes, it should be 4 times the diam. of the wheel to be cut, or more if possible. (See p. 44 of present vol. for some remarks on dividing pegs.)-J. K. P.

[3955.]-SCALE PARAFFIN-I should think the quantity of scale paraffin produced last year (in Scotland) would be about 1500 tons.-REFINER.

3

[3956.]-WEIGHT OF GAS.-See G. E. Davis's letter. [3957]-POWERS OF NUMBERS.-I believe the easiest way is to make use of the formula log. (an) = a log. a; for example, if we have to calculate x=-, I put log. x = log. 10 =

3

3

Б

5

log. 100-60000, and I find that 0.60000 5 is very nearly the logarithms of 0-3982; thus x = 0-3982. BERNARDIN,

[3964]-CAST IRON-Chipping is as much an art, and to be done really well requires practice as much as filing does. Any smith any where will draw you out a chisel and show you rolled for the purpose, or round, flattened on the sides. I keep how to use it. The steel generally used is either octagon an earthenware pan in the garden, and put a casting into the acid water left from last time, and then pour in strong sulphuric acid, till I see the hydrogen come away freely, and leave it for 12 hours. This will bring most of the sand away.

I think the best stuff to make casts of for electrotyping is white wax with a lot of rottenstone melted up with The powder makes the cast hard, prevents it shrinking so much, and makes it heavy enough to sink in water; it blackleads very well too.-J. K. P.

[3937.]-CHEMICAL QUERY.-See "Urban's " letter. [3937]-CHEMICAL QUERY.-As liquid nitrous oxide raised to a gas at 0°C. and 760mm. is just at the normal condition for calculating gases, it is only necessary to divide the 200grms. by the weight of a litre of the gas, which may be calculated it. off hydrogen as follows:-As a litre of H = 0896grms.; therefore a litre of ON, (density 22) = '0896 × 22 200grms. = 101.46 litres, the answer Consequently ·0866 × 22 required.-NIGHT SCHOOLBOY. [3941.]-MARKING INK.-If" Daisy "put the ink on a piece of velvet, and then rubbed it over the types (or to glue it round a roller would be better), I think he would succeed. I have used the ordinary writing-ink that way, and found it

succeed.- PRINTER.

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[3950.]—GOMUTU FIBRE-The Gomutu palm is the sugar palm, Arenga saccharifera, Labill, occurring in great abundance in a wild state throughout the islands of the Indian Archipelago, and cultivated generally by the various people who inhabit this region. The Malays call the tree "anoa," the liquor (toddy) obtained from it "tonak," or "nera" the horsehair-like material covering the base of the petioles "Edju," or "Gomutu;" the Portuguese call the tree" "Saguero," " sago tree,' ," or "Sagwire." The fibrous substance of the base of the petioles-superior in quality and cheapness to coir or cocoa-nut fibre, is used by the natives for every purpose of cordage. The coarsest parts are used as pens by all the natives who write, and also as arrows for their blowpipes. I do not find any mention of these fibres being employed for brooms or brushes. Cabo negro is, according to

[3967.]-MAGNETIC NEEDLE.-In a vertical galvanometer the strong needle would give the greatest deflection; in a horizontal galvanometer there would be a slight difference, as both the forces would diminish alike by the weakened magnetism; the difference really found would be due not to the magnetic difference, but to the relation of the actual deflecting force to the weight of the needle-i. e., its inertia, and to the friction on its support. In my own experiments I have found that with everything the same in other respects, different needles give different deflections, but the same needle weakly or strongly magnetised gives the same.SIGMA.

PAINTING WOODEN PAILS.-The practice of painting the inside of wooden pails, to prevent leakage, is only to be recommended when the paint contains no white lead or baryta, both of which we found in the paint of some pails examined lately. All over the country these pails are used in the kitchen, and although either lead or baryta are not very soluble in water, yet frequently the paint peels off in flakes, and may have sericus consequences when getting into the teakettle, and thus into the food. The paint for such purposes should be either whiting or gypsum, if required white, but the most preferable is ochre, against which the sanitary objection cannot be raised.

NOTES AND QUERIES.

(3972.]-IRON STAINS.-Could some brother reader tell me what will remove iron stains from linen or calico? The question has been asked before, but never answered.-J. H. P. [3973-A WATER VELOCIPEDE.-Noticing that you have taken great interest in your journal in the velocipede movement, I make free to ask if you can tell me where I can get a water velocipede. I have recently lost my right arm so am debarred from taking part in most outdoor amusements.-J. D.

FLUTE.-Would H. T. [3974.]-BOEHM Leftwich kindly give a detailed working account of the "equisonant fate," also where it can be obtained, and if it is much more expensive than the old flute? Can he or any other reader say where I could obtain keys and fittings for the same and other description of flutes cheap.-ANOTHER FLAUTIST. (3975)-VALUE OF COIN-Can any reader tell me the value of a coin in my possession, of which I send a sketch?

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[3991.]-DARK LINES IN SOLAR SPECTRA-Will "T. A." say how, according to his atmospheric hypothesis, he accounts for the dark lines in the spectra of the fixed stars; they being totally different from the solar spectrum and from each other? If the amount of iron, for instance, necessary to produce the iron lines in the solar spectrum is, as he says, contained in our atmosphere, and continually falling to the earth, is it more than probable that the Bunsen burner would give some indication of it in the same way as it does of sodium ?-STEERSMAN.

[3992.]-SIZES OF ROPES.-Having read with pleasure the article on "Strength of Materials," bearing as it does on my own trade, I should feel obliged if any one could inform me if there is any published tables of the number of threads and strands for given sizes of circumference and diameter of ropes from the smallest to the largest sizes ?-ANXIOUS TO LEARN.

[3994.]-ELECTRIC

[3993 ]-PASSAGE TO NATAL.-Will any one inform me through the MECHANIC the best and cheapest way to get to Natal, South Africa.-A CORNISH MAN. MOTOR FOR SEWING MACHINE-I see from a back number of " All the Year Round" that a Frenchman, Mons. H. Cayal has invented an electric motor for working a sewing machine. I should be much obliged to any one who will give me some particulars about it? J. H. MERIVALE, Ealing.

[3995.]-BOOKWORMS.-Can some reader inform me what will effectually destroy bookworms without injuring

the books?-BOOKWORM.

[3996-BOOKBINDING.-Will any of our numerous subscribers tell me whether brass type or handle letters will be best for me (an amateur bookbinder) for gilding letters on the covers of books, also the price of leather per skin, and cloth for bookbinding per yard?-Q. Yorkshire.

The characters are roughly formed and raised. It is, I believe, occasionally, where a glass rod is made to revolve. I have silver.-HARRY G. NEWTON.

[3976.]-BRITTLE INDIARUBBER-I observe that sheets of vulcanised indiarubber become brittle after some time; what may be the cause of this? Is there any means of preventing it?-CAOUTCHOUC.

[8977.]-BRAZILIAN RAILWAYS.-To what extent are the different railways diverging from Bahia in activity? Are the constructions advancing?-H. Z. Y.

[3978.]-ROUND ZINC WIRE-Is round zinc wire manuactured so small as No, 22, B. W. G. I have tried several wire mills, but cannot get it.-THEORUM.

[3979.]-BRICKS AND POTTERY.-Will any reader tell me of a good practical work on pottery from which I could gain a knowledge of the different operations carried on in the potter's art; or a good book on brickmaking? I have Mr. Dobson's work, published by Virtue, Bros., which is a a capital rudimentary treatise, but I should like something larger, with more detail, if possible.-OLD SUBSCRIBER.

[3980.]-CLINTON'S FLU TE.-I hope Mr. Leftwich wil be so kind as to accept our Editor's offer. I see he recom-1 mends Clinton's flute. Has he ever tried Carte's improved

Boehm flute.-J. H. M.

[3931.]-BOOKS.-Will any reader inform me in your next publication of the ENGLISH MECHANIC if he knows whether there is a book published that gives the weight of different sizes and lengths of iron, viz., rounds, squares, flats, &c., allowing for heating, rolling, and cropping, the name of it, and where it can be bought? Or can you recommend a book to assist a mill manager in his work, one with tables giving the weight of the pile to produce finished bars? An answer through your valuable journal will oblige.-L. M. [3952.]-WORKS ON SOAP MAKING,-Could any of our readers give me the names of the authors and publishers of any good practical books on the above subject? Also, if they could refer me to any periodical or journal where good papers or articles have appeared on the subject?-M. G. MORGAN.

[3983.]-ENGINE INDICATING.-If some one of our excellent correspondents could kindly give me a little instruction on engine indicating I should feel greatly obliged. I have heard of one young man in this neighbourhood who is giving as much as 5s a lesson for instruction on the subjeet. I believe it would be interesting to many of our readers. What I want to know is, how to take a diagram, then how to measure it up so ás to get the power; and how I must get the pressure per square inch? The diagram before me is divided into 40 lines, and every fifth Ene is extended to the margin and marked "Atmospheric 5, 10, 15, 20" upwards, and the same downwards, but the fifteenth line downwards is marked "Vacuum." I should be glad of an explanation, and also wish to hear of a good book on the subject.-VACUUM.

[3984.]-ALUMINIUM BRONZE.-I shall feel obliged if any of your readers can inform me of the proportions used in the mixture of aluminium bronze.-ALUMINIUM. [3985.]-FLEXIBLE PIPE.- Would any reader inform me if there is any flexible pipe that will stand boiling water, or if indiarubber canvas hose pipe would answer the purpose? E. L. V.

[3986.]-CYANIDES. TO "SIGMA."-Would " "Sigma say where I can get the latest information about the manufacture of cyanides from the combustion or heating of char, coal with nitrogen and potash; also if soda-barytes, &c. have as good effect as the potash ?-J. W.

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[3987.)-OIL TESTING MACHINE.-I use a great deal of oil for lubricating purposes, and 1 have observed in your machine Can any of your readers inform me the machines that are now generally approved for that purpose?-WM.

(4011)-PRICKING BARRELS OF BARREL ORGANS. Would "Adept" or any other subscriber kindly describe in detail the process of pricking the tunes on the barrels of mechanical organs? I should be very greatly obliged for such instructions as would enable me to set out tunes and over

tures on the barrels of an organ having a complete scale, and working its own stops.-PUPIL.

[4012.]-WORM-EATEN ORGAN BARRELS.-Can any one inform me what would prevent dry wood from being worm-eaten (weevils I think they are called)? Some of my organ barrels are becoming completely honeycombed by these troublesome creatures, and I should be glad to know if there is any solution which will kill, or prevent them from doing further mischief. -PUPIL.

Also

14013.]-TO N. S. HEINEKEN.-Would N. S. Heineken kindly state the price of " Le Manuel du Facteur d'Orgues," and where in London or Paris it could be obtained? state if it gives practical instruction in organ building?— PUPIL.

[4014.]-MEDICAL ELECTRICITY-Will one of our knowing friends kindly answer one or two questions:-1. I have seen it stated that a current from a secondary is of no use for medical purposes; but only that from the primary wire-Is it so? 2. Will an induced current induce a current I have seen a beautiful little in a coil laid on the second? apparatus made by "Rosenbloom" (I think that is the name) the current of which might be modified in a most simple and beautiful manner. On the baseboard there were a number of brass studs, numbered from 0 to 16, placed in the form of two

arcs.

These communicated under the board with fine wires from the coil. Attached to binding screws were two brass movable arms which, on being placed on corresponding studs, would vary the power of the current. When placed on studs No. 0, it was so gentle that a child could bear it with pleasure; but when moved to the highest number, it would [3997.]-ARTIFICIAL FOUNTAIN.-I wish to make an be sufficient for several adults. A friend of mine who has one artificial fountain, the same as seen in watchmakers windows has been very successful in relieving many obstinate cases of contraction of limbs, rheumatics, &c. Now I think if an the movement of an old watch, and 3 small cog-wheels, but affirmative can be given to both my questions, then an I cannot manage to fix it in any way. Would some kind apparatus with various shades of power can be easily made friend give me a few hints ?-T. P. by coils of various lengths laid on each other, their ends com[3998.]-ORGAN MOVEMENT TO HARMONIUM.-Imunicating with the corresponding studs. I may just say Will have made a harmonium with two rows of reeds. the coil was worked with a single pair of plates C and Z, the C "Lever" or any other tell me how I can put the organ moveabout lin. by 3, the Z in the form of a U, so that each side of the C was used.-O'BEC. ments on. I see on my catalogue that I can get the full Could any one tell me what organ movements for 3s. 6d. they are, and how they are fitted on?-YOUNG AMATEUR. [3999.]-CYLINDER.-Will any reader be kind enough to give me the dimensions of cylinders for small steam carriage? -IXION,

[4000.]-SODA WATER.-Will any brother reader be so kind as to inform me how to test a very small quantity of tartaric acid in a tumbler of water from citric or vice versa. -ONE IN A FIX.

[4001]-ATMOSPHERIC INFLUENCE ON ELECTRIC CLOCKS-Has the atmosphere any influence on electric elocks?-ELECTRIC.

[4002.]-MUSLIN DRESS.-I have a muslin dress, Will originally a bright violet, but now very much faded. any of your numerous correspondents kindly inform me either how to extract the colour entirely, or to restore it?-BETA. [4003.]-WATERING GARDEN.-Will anyone kindly inform me of the easiest and cheapest plan for raising water and watering a garden, say 20yd. long? The river runs close to the garden, but is about 8ft. lower than the level of the ground. Something of the force-pump style, but less expensive?-F. H. JONES.

[4004.]-SPECTROSCOPE.-Will "F.R.A.S." kindly give us another paper describing "some rude and makeshift apparatus by means of which rudimentary spectroscopic observations might be made," as it would be very acceptable to many of his readers. Also will he say whether solutions of sodium, lamp and slit of the spectroscope; if so, will he tell us which salts, &c., will give absorbtion bands if placed between the solutions will give us the most striking results as experiments? I hope he will do what he intended in relation to Sirius, as I am sure the Editor will not deny him as much space as he likes for what is interesting to so many of his readers.-H. W. BISHOP.

[4005.]-GUN BARRELS.-I should feel much obliged if anyone will tell me how to clean the inside of gun barrels in the lathe, so as to make them look like the gunsmiths do ?A NEW SUBSCRIBER.

[4006.]-DRESSING STONE.-Can any reader inform me whether there is in operation any machinery for working or of Lancashire and Yorkshire.-STONEMASON.

dressing the hard grit stone such as is used in the buildings

[4007.)-CURING HERRINGS.-Will you kindly allow me to ask if any of your readers will tell me the way to cure herrings, or name any book giving such information.-J. BASKERVILLE,

[4008]-GRAINING STUFF.-What is the colour made of that grainers use for oak grain, not the ground colour, but that over it.-J. BASKERVILLE.

[4009.]-HEATING BOILERS WITH GAS.-Will some brother reader give some information respecting heating steam boilers with gas. I believe they require very little attention, and can be kept in readiness for work by turning on sufficient gas to keep the water boiling. I think also that insurance companies do not charge extra premium where these boilers are erected. These are certainly very great recommendations if there are no corresponding drawbacks. I had thought an ordinary vertical boiler would answer if the furnace bars were removed, and gas pipes put in. I should think the flues ought to be smaller. Possibly one tube bent

[4015.]-ARTS EXAMINATION, ROYAL COLLEGE OF SURGEONS.-Will some brother reader who has passed the above kindly inform me what is the minimum number of marks, and how soon one is informed if he has passed?GADDHA.

[4016.]-ARMY COMMISSIONS.-Will anyone inform me through the MECHANIC what is the limit of age for purchasing commissions in the line regiments? On referring to the Army Regulations I find 17 to be the earliest age at which a commission can be held, but it gives no other limit. For men it is 18 to 45, what is it for officers?-LINESMAN.

[4017.]-CRICKET BATS.-Would some of my brother readers versed in the manufacture of cricket bats kindly give some information as to what kinds of wood are used for the also how made; the respective merits peculiar to purpose; each kind of wood; in short, any information that will guide a lover of cricket in making his own bats?-STUMP.

[4018.]-ISOMETRICAL DRAWING.-The sense of my query (3923) was lost last week by the substitution of the word "geometrical" for "isometrical." Readers who intend to favour me with a reply will kindly notice this correction.C. J. H. COTTHESON.

[4019.]-SAFETY VALVE.-I want to have 20lb. pressure on the square inch of a boiler, the length of which 18 11in. long by 6in. broad, and 4in. high. Would "Jonath" kindly give me the rule for finding the size of safety valve, length of lever, &c ?-O. G.

[4020.]-WOULFFE'S BOTTLE.-I have a 3-necked Woulfe's bottle, but in two of the necks the glass has not been taken out in the inside so it is of no use. How can I take the glass out without injuring the other part of the bottle? Would a common diamond do to scratch it, and could the glass be then knocked out?-M P.C.S.

[4021]-COINS.-Will some brother reader inform me what the following coins are, and their relative value? A coin (silver) slightly larger than a sixpence. Obv: female bust Anno. Dei. Gratia. Rev: 1777 Mag, Bri. Fret. Hib. Reg. with large cross. Another the same in circumference, but thinner than a shilling. Obv: (I take it) CAROLVS. VI. D. G. ROM. IMP. SEMP. AVG. with double-headed griffin with mace and a sword, 1.H.L. in small capitals. Rev. Castle with wreath around, and below a circle with

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inside. Around margin, Hamburger. Current 1725.-VELOCE.

[4022.]-TUNING BELLOWS FOR HARMONIUM REEDS, &c.-If our talented correspondent "Eleve" will answer the following questions I should feel grateful:-1st. Which way must I set about to make a pair of tuning bellows that will answer for tuning any size reeds, or where could I purchase one similar to those used in large establishments? 2nd, What sort of "holders" to hold the reeds (any size) during vibration? 3rd. What construction of bellows to keep a continual vibration at pleasure without breaking off the wird? Would a couple of bellows answer, one to go up while the other is going down? Details with diagrams would oblige. -REED TUNER.

[4023.]-ORGAN STOPS.-Will the "Harmonious Blacksmith" or "Adept " please give an opinion on the following? I am about to build myself a small organ with about 4 stops, which stops would suit best? I have thought of open diapason, stopped, principal, aud fifteenth, or would a flute in

journal some time since an advertisement of an oil testing into a spiral form running from bottom to top would give good place of fitteenth answer better -Jos. B. CROSSLEY.

JOHNS.

[3988.]-STUFFED BIRDS.-I have 37 Australian birds which I want set up in case with glass front. The case is 4ft. by 34ft. and 13" deep. The birds vary in size from magpie to humming bird. I should like to construct an artificial tree, but don't know how to proceed. If any kind friend would give me sketch of tree and instructions how to make it through your valuable paper, he would extremely oblige ONE IN A FIX.

[3989.]-SCREW ENGINE FOR CANOE.-How large a serew engine with double cylinders ought one to have to drive a canoe 15ft. long and about 24ft. wide; also size and shpe of boiler; also about what price if I buy them?-A YOUNG SUBSCRIBER.

[3990.]-YELLOW DYE-Will any reader tell me how to make a deep yellow dye that will stand the air?-A COUNTRY MAN.

heating surface, and be sufficient to carry off the products of combustion. I should like to know also whether there is any objection to feeding a boiler with boiling water; it seems to me it must require a deal less fire in the furnace to raise the same amount of steam.-CORN FACTOR.

[4010.]-MELTING AND CASTING METAL-Would some experienced reader be kind enough to assist me in the melting and casting of a metal si ilar to printers type metal, sharp cast of designs I have, the moulds of which are of iron but much harder when cast. I want to get a nice clean and brass, and will make a cast about in. square and about in. thick, I have tried zinc, tin, and other metals, but without success. I should like to know the exact proportions of metals to mix to get what I want, and whether it should be melted in a ladle or crucible, and how to tell when hot enough, and if anything should be put on the mould to assist the sharpness of the cast; in fact anything that would be neces sary for anyone ignorant of the process to know would be most thankfully received.-A BRISTOL AMATEUR.

[4024.]-GALVANISING CAST IRON-Would any of your readers kindly explain the process of galvanising cast iron. Mr, Meredith in one of your "replies" says the process is the same as for wrought iron; but not knowing the process I am compelled to trouble you again?-B. WEBB.

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