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[104] SIR,-I find in your paper of July 1stja letter from Mr. Harrison, in which he questions the truth of Mr. Baskerville's theory as regards the link motion. Now I advise Mr. H. before he so emphatically contradicts Mr. B., to carefully examine Mr. B.'s diagram of the link, in your paper of June 17th. The link is there represented in "middle gear," and it is evident that the excentric rods must lose length in the direction of the motion line when they change from position A to position B, the loss being due to their angularity when in position B. Those letters refer to Fig 1.

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Throw of excentric
Advance of excentric
Length of rod

Length of link
Lap of valve
Lead of valve

5

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to the soloist, enabling him, as they do, to produce
those dashing and sparkling effects so charming to the
ear. I know "personally" that the Boehm flute has
them to a great extent-in many passages they are
indispensable to its system; but the Equisonant has
them to a still greater extent, and the tone is much
clearer and purer. I have spoken the truth, but I do
not expect that any manufacturer or professor will
acquiesce in what I have said if it be against his
interests.

The late Mr. John Clinton was a great master, his
magnificent transcription of Meyerbeer's exquisite
cavatina, "Robert, toi que j'aime," and own graceful
and brilliant "Grande valse-Reve d'un Bal," are
enough to establish his fame, to say nothing of a host
of original works of which his reviewers have said.
sufficient. He lived but to see the only prize medal
awarded to his flute "for improvements on the system
of Herr Boehm," his early colleague.

SABLE.

POWERS OF BLOCKS AND STRENGTH OF
ROPES.

LINE

[106] SIR,-I enclose a few diagrams of blocks and tackles which might be of service to many of our readers requiring such mechanical appliances. This subject has already been alluded to in our MECHANIC, p. 67, Oct. 8, 1869, but is there so imperfectly treated that I venture to bring it before you again in fuller detail and form. Fig. 1 is the single pulley, which only changes direction. Fig. 2 is an arrangement which gives power equal to 2 to 1. Fig. 3, the same, but is more convenient for being portable, and gives the first impression that the increase of folds gives the same proportionate increase of power. Fig. 4 having two sheaves in each block gives power equal to 4 to 1. Fig. 5 gives a power of 5 to 1, Fig. 6 a power of 6 to 1, and Fig. 7, a power of 8 to 1; thus showing that the increase of folds is the increase of power, and that the weight suspended in lower block is equally 5" divided over all the suspending folds alike; and the weight required on the fold to suspend a given weight in the blocks is in proportion to the number of folds suspending lower block. Fig. 8 is Weston's patent blocks. The lifting power is given by the difference in diameter of top block sheaves, and the peculiar cross on the chain; motion given to which either adds to, or takes from he length suspending weight.

1

5' 1"
1' 4"

I send for Mr. H.'s instruction a diagram (Fig. 2) of a link motion. If he lays it out in two opposite positions in "mid gear," he will find that the valve, or in other words the middle of the link, will move exactly 24 inches. JAMES F. RYAN.

P.S.-A great many of your readers are anxiously looking for a few good letters on iron girders and bridge work in general. If one of your clever correspondents would give us a few good rules on strains and the proportions of girders, he would confer a favour.

CLINTON'S PRIZE MEDAL EQUISONANT
FLUTE.

I ex

LINE

And further to illustrate the principle of gaining power by blocks, Fig. 9 is a modification of Fig. 6, showing that by suspending 6 cwt. a strain of 1 cwt. will be the result on any part of the line. The figures in the illustration correspond to the balance of power

attained.

To the above it is necessary to subjoin a table of the diameters, circumferences, working strains, and breaking strain of hemp rope for the above purpose. The rule to be observed is the working strain in cwts. on the old, multiplied by the number of folds suspending under block will give the number of cwts. which said block is safe to lift:

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[105] SIR,-Pray suffer me to thank "Justitia," page 376, very cordially for his generous and manly letter, which is a credit to both his head and heart; it is a refreshing contrast to that of "Orion." pected Mr. Leftwich, or some more able champion than myself, would soon enter the lists in veritatis et justitiæ causam. "Orion" did not think much of the fine flute of this distinguished composer and per- 18,, former. A little sober reflection would have saved him 11,, = 48 from writing that letter in which he did himself a One third of this sum in tons is breaking strain. Say greater injustice than he inflicted on Mr. Clinton's a pair of blocks two and three sheaves with 14 in. rope, memory. "Justitia" has left me little to add in what is the working power and breaking strain on blocks favour of the Equisonant. Personally I know this of and fold? On table working strain is 10.2 x 5 = 51 it. Its tone is beautiful if it be fairly elicited; its cwts. working strain on blocks, and divided by 3 is notes are equal in strength, tune, and firmness, and 17 tons, breaking strain on blocks, and this divided its great recommendation to flautists of the Nicholson by 5, the number of folds, gives 3-4 tons as breaking school is, that its scale of fingering is natural, differ-strain on fold. ing so little from the eight-keyed flute that it can be adopted with ease by ordinary players. These are ACCUMULATING AND UTILIZING POWER. advantages not to be overlooked. I need not, I am sure, remind "Orion," whom I strongly suspect to be [107] SIR,-Will you allow me space to make a few in "the profession," of the great value of " harmonics" remarks upon your correspondent's query upon the

J. HOVELL.

above as contained in your journal of the 1st inst. which I have just seen? "River Plater" asks if it is possible to accumulate sufficient power, whether by means of horse or wind, as to be available at some future time. I shall not attempt to answer such, but will state what I heard in the River Plate (Buenos Ayres) in 1857. When locomotives were first introduced on the Western Railway, a native asked me what was the power of each locomotive. I told him so much. His reply was, "How so: I do not see any horses in the machine? where do you put them?" and when the steam was issuing from the funnel, a cry was set up it was "white magic." There are such objections as your correspondent points out, attending the cost of coal, but to wait until the plantations are large enough to supply the fuel consumption is absurd, because colonization increases in a much greater ratio than the fuel (trees) can, being only planted lately.

To invent a machine that shall have a spring (so to speak) capable of being wound up to supply power for even the next day, for such a thing as a Fowler plough, would be attended with considerable difficulties. Now to accumulate the power of horse or wind to such an extent is impossible. Water power is considered the most available from day to day. Under ordinary circumstances we can depend upon it, yet in the River Plate provinces such is not at all to be depended upon. I have crossed the "Somberambom" when my horse could skip across, and in a few months I have ridden fifteen miles through water before coming to the same river. Having spent several years in this country I am enabled to speak from experience.

I should try and introduce the "Aydon Liquid Fuel" as being cheaper, a more ready generator of steam, and far better for transportation.

There are other materials for fuel in the sister empire far better, and less expensive, than coal.

TO MILLERS.

J. G.

[108] SIR,-Perhaps some of your correspondents will give me their opinion respecting fast or moderate grinding-say, whether they prefer six to eight bushels per hour, or from three and a half to four bushels per hour. It is my opinion in fast grinding you lose your colour, also your length. But there may be some one that can tell how to get both. I have heard a great deal about Bovill's cold blast and exhaust; the cold blast I am hard of believing in. But, as I say, perhaps some of your more intelligent correspondents may give me their opinion respecting it. Also, what length should you have a silk for (say) six pairs of stones grinding (say) four bushels per hour. A SUBSCRIBER.

THE SUN'S PARALLAX.

[109] SIR,-Referring to "Hugo's" letter upon the sun's parallax, on page 402 of the ENGLISH MECHANIC of July 15, 1870, before answering that letter, will you be kind enough to allow me to ask "Hugo" to test or verify his figure by actual calculation, as he says "he is confident the parallax thus formed will be that which is generally accepted to be true ?" The mean parallax of the sun is given by some at 8"-91, and by others at 8"-65, &c., &c. "Hugo," I submit, is bound in honour to give by actual calculation what he considers the "true" mean parallax of the sun, because he has said that which has been given by "Veritas" is not "true;" otherwise, how does he know ?

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circle. The inner line of the rail is described parallel to the outer one; this will always give the open space required for the hand. CYMRO.

THE "PHOENIX" VELOCIPEDE.

the back and filling in with lead in order to counter-
balance au overplus of weight in a bar or burs in
the face at the opposite side. Now, as the lead is 5in.
above, and the heavy bur or burs (intended to be counter
balanced) 5in. below the centre of the bar or bale, the cou-
sequence must be that as soon as the stone gets into a

swing, centrifugal force must bring the lead down and
the heavy bur up, just as the balls of a governor have
a tendency to rise to the level of fulcrum on which they
are hung; now, if my dusty brothers who are troubled
with stones being out of standing or running balance,

possible to the nipple of the slow spindles, and pour in
the necessary weight of lead, I do not doubt they will
known millers who prefer the plan to balance boxes,
find the stone cured of its tendency to roam. I have
because it is not possible to get out of order.

disputed against it.
novelties. The French are diferent. They are at one-
enthusiastic, and the bicycle is the machine for them. !
But though John Bull is too slid
is their machine.
conservative to trust himself at once on two wheri
yet he is turning round, so much so that I'm convia
he will in a few years adopt the bicycle as a useful an

That is his plan of welcoming

pleasant mode of conveyance.

When I got a bicycle and began to practice on it me people hereabouts pronounced it as folly. "A great de of hard work," and that it "would have its day" was th usual cry; but twelve months have altered their opini have since become riders.

[111] SIR,-Having been greatly interested in secing the numerous and varied descriptions of veloci. pedes which have been illustrated and described in the pages of your interesting and valuable paper, I wish to offer to your readers a brief ontline of a three-wheeler, will only dig out a hole between the hoops as near as for upwards of two dozen fellows of our small tos the capabilities and qualities of which I have fully tested during the last twelve months. I have named it the "Phoenix," partly on account of several important parts having been used in a somewhat similar machine made by my father over twenty years ago. It is constructed to carry two persons; the front wheel (3ft. diameter) is fitted with a steel axle and cranks; and is mounted in a fork with a steering handle on the top, exactly similar to the front part of an ordinary bicycle. The two hind wheels, each 3ft. 6in. diameter, are firmly fixed on the ends of separate axles; the inner ends of these axles working in one bush fitted in the frame, gives the appearance of being only one axle. On about the middle of each of these axles is fitted a steel ratchet wheel, and loosely over these are cases having each three pawls; these cases have grooves on the outside in which are secured the ends of strong catgut cords, in which passing over the cases go down to levers or treadles provided with india-rubber footsteps; the levers are also

In further answering "N. S. L." I may state that us doubtedly the bicycle is a better machine in every wa knowledge. Let "N. S. L." and all his proselytes le than the three or four wheeler. I speak from my o thoroughly the use of the bicycle-which, it is evident he knows as yet little about-and they will at once dis card the multicycles. It requires less exertion to dris The force applied is direct and in the proper and mis natural and easy direction. It is safer and quicker is this respect I'm behind many of my brother riders. Ex turning-with many other indisputable etceteras. I have never yet gone fifty miles at a stretch, but in I can ride over most hills, although over some the sweat

ing (not so much the labour) is great.

There is still one "moot point" to be settled which " S. James" (page 374) has already laid before you readers. We want an impartial and well grounded medical opinion which must be given in full length, with causes, effects, and reasons, whys and wherefores all annexed. For my part I can say that I have ridden or rupturous effects.

connected together by a catgut cord, which passing over tap, when a pail full of water so heated will register continuously for hours together and never felt any evd

a roller, so the descending lever lifts the other. The
advantages gained by this arrangement of three wheels
are-great facility of steering, especially turning sharp
curves, as each wheel being on a separate axle
they work independently of each other; the ratchet
wheel and lever arrangement for driving the hind
wheels gives a powerful and convenient mode of work
ing for the second rider; and there being no dead
points (as with cranks), in whatever position the levers
are placed at stopping, they are right for starting. In
going down hill he can rest his feet on the steps, as the
wheels can go independently of them. It will be seen
from the description of the front part that the rider
thereon works and steers just the same as on the
ordinary bicycle. For two riders I consider it to be
the best machine I have yet seen or read of, and shall
be glad to learn the opinion of my fellow readers of the
ENGLISH MECHANIC.
W. D. R.

BICYCLE RIDING.

In reading Jas. Baskerville's criticism's on Llah's water heater, which I thought an excellent plan for feeding a boiler with one pump, I trust I shall not be intruding if I describe a water heater which I put up in beam. I pump the cold water directly into the exhaust 1863, and have still at work-the engine, a 10-horse pipe, a few feet from the cylinder, the exhaust pipe going horizontally to the heater or depositing reservoir, as it may be called, as the water is really heated by the exhaust steam, driving it into the heater in the shape of a fine spray, thereby heating it nearly, or quite, to 212 degrees, as can be proved by drawing ont of the suction pipe of the hot water pump through a in the heater instead of carrying it into the boiler. 207 degrees; by this means the water deposits its silex My heater is 7ft. long by 14in. diameter, lying in a line with the exhaust pipe, and I can hear the spray blown overflow pipe at the middle, also one rising to the open to the end at every stroke of the engine. I have an and save fuel. I have seen somewhere that 9 degrees air. I condense many gallons of water by this means, of heat in boiler-feed is equivalent to 1 per cent. of fuel saved, so conclude that I save 18 per cent., besides the advantage of having soft water for the boiler. I am obliged to clean the exhaust pipe once a year from silex, as I once had it form so thick as not to be able to drive one pair of stones with 45lbs. of steam. I also find it necessary to have the heater a little above the hot water pump, or it will not draw.

ONE EYE.

PROFESSOR PRITCHARD'S REVIEW OF

"OTHER WORLDS."

It seems

[114] Sr.-As an old reader, may I be allowed to [112] SIR,-Your correspondent "N. O. Lamborne" enter a word of protest against that practice of indulg. asks for answers to several questions which, as a practi-out in your "Correspondence" column? Although it ing in personalities, which every now and then crops cal bicycle rider having had fifteen months' experience, I may be highly entertaining and gratifying to the taste think can be easily answered. It does not require any of some, I think I may say with truth that it is quite great amount of practice to enable any lad to ride on a otherwise to the majority of your subscribers. smooth road. A week, with an hour each day, would I think Mr. Proctor has shown very bad taste in be amply sufficient. Of course some care must be criticising Professor Pritchard's review of "Other exercised, but nothing extraordinary. If the bicycle is Worlds." In the first place, for answering the critique at all, since if it be an unfair one the merits of the book bad the best of riders could not prevent it wobbling, itself will themselves answer the criticism, and if the but unless the road is an extraordinarily bad one this review did not do it an injustice, why, the less said about would not happen with a good machine. There is no it the better. Then, in the second place, I do not think danger to a practised rider when passing a waggon in a it was exactly the right sort of thing for Mr. Proctor to narrow road, for the bicycle has an advantage over any insert letters upon a review (which appeared in another other vehicle in that it can run in so little space, besides publication) in the ENGLISH MECHANIC, which perhaps being able to run into the grass if that skirts the road, Professor Pritchard does not ordinarily see. or into the gutter if in a town road. I never saw any very much like trying to steal a march upon Professor Pritchard. I am afraid that Mr. Proctor is very thindanger of falling in turning a sharp corner, but cannot skinned. CHARLES BRANDON. say if there would be if going at great speed, which is a dangerous proceeding with any vehicle. Power over the machine is lessened, but never lost with a good rider, and if the front wheel rubs the thigh it is an evidence the rider needs practice. It is possible, but not likely to happen to a good rider, to put his eg through the front wheel any more than the hind one. The comparison between the sitting on a low chair placing the feet 18in. forward, and then trying to rise may perhaps apply to a case where the seat of the bicycle is far back on the spring, but in my machine you are so well forward that one may almost say they sit over the front wheel, which, by the bye, I believe is rather a rarity, although a great benefit to the rider.

THE BICYCLE.

[115] SIR,-As a votary of the bicycle I ask the liberty of answering N. G. Lamborne's questions on this subject (page 376). The number of his questions must be an excuse for brevity in my answers.

THE FLUTE.

HCSBAND.

correspondent, "T. S. G.," advises "Stiff Fingers" to play tuning slide.

[116] SIR.-In this week's ExGLISH MECHANIC I see that in certain keys and to produce some of the others by the He says "the music being in D flat he

shoul1 by means of his slide tune to the D flat of the
piano." It is quite evident that "T. S. G." has had but
little experience, or he could not have advised such a
course. The smaller a finte is, the nearer the holes and
In a piccolo, for instance, the
keys must be together.
distance between the holes is only half of what it is in
slide, it must play out of tune-particularly in the upper
the concert finte. Is fute is lengthened by the tuning

octave. The tuning slide is only intended to alter the
pitch very slightly, say, or at the most, of a tone.
J. R. RENDELL.

[117]

SWIMMING, A SUMMER PASTIME.

SIR,-I wish to thank T.S. H." for his verificanavigation, and in reply to his call for a few notes on tion of my determination of spherical route of circumswimming, I beg to offer a few from my own experience. I had a wish to learn this art from early life, but my avocations led me generally inland, and to places where practice was impossible, till I had passed the middle At last I came to within a mile of term of human life. convenient water, and although my past limited experi ence. led me to suspect that I was specificially heavier than water, as my efforts to swim were always brought to a termination by the sinking of the whole body, head included, below the water, still I resolved to bring the matter to a test of a whole season's daily practice before considering my suspicion confirmed. For some time this was like to be the case, but at length. in one of my daily trials. I found my head, quite unes pectedly, above water. I was at a loss then to assign satisfactory reason for this result, for I had often stra with both hands and feet precisely, so I thought, in the same way, with a different result. Be this as it may, I never sank after this, and I found myself on each cessive daily trial able to accomplish a few more strokes. till at length I swam on one occasion, fifty minutes with out feeling cold or fatigue, and without touching the continues to be a source of refreshing enjoyment to me bottom. I need hardly say that the practices but although I can swim quite comfortably for a long time, when allowed to do so leisurely, still I find myse a slow swimmer whatever efforts I choose to make. I am at a loss to explain to myself the reason why: but the reason of my early failures, the sinking above m ferred to, I now conceive to be that I unconsciously ke my head in line, or nearly so, with my body, wheres there ought to be en angle somewhere about 135 degre between the axis lines of the body and the head. wished, and here lies the difficulty, in my opinion. experience in learning to swim, a difficulty peculi man as distinguished, by form, from many anima swim with case on the first trial; and hence als desirableness of learning to swim on the side and b in which position the angle at the back of the neck becous 180 degrees, and the position is consequently one of plete rest. Not only is it a position of rest, but the body cular effort in either arms or legs; a very slight effort in the floats without any tendency whatever to sink, with no m muscles of the loins being all that is necessary, so far a I can judge, to preserve the linear position of the hody from head to feet. In this position there is about lis vertical section, of the face that positively will not sink. The effort to throw the head under water results in deeper immersion of the forehead with a greater corre sponding elevation of the month, and thus the position even to wash the feet and body generally with both is a most happy one to rest in for any required time, of hands, for it appears to me generally certain that the floating of the body does not depend, in any sensible degree, on the position of the arms so long as they are kept under water. I conclude generally that to swim swiftly and gracefully is a difficult matter for most men: but that every man's body will float, and that almost any action with feet and hands, all four at once, or any pair at once, will produce progression, more or less swift and gracefully according to the symmetrical action of the whole system.

I shall believe in ruptures when I have some per- that the fusee will touch one's nose in lighting a cigar angle is not quite so easy a matter to ol tain as could be

sonal knowledge of their having resulted from riding. As regards personal injury in jumping, or rather bucking, on to the bicycle there is no necessity to do so with the majority of machines.

Upon coming to a very steep hill you have only to ask yourself which would be the easiest, to work the machine up to it, or get off and walk it up, in which latter case there is no need to dirty oneself. I think I have answered most of the questions, if not all, fairly, but I must say that the space you have granted this letter is wasted, for had " N. O. Lamborne" asked any bicyclist the same questions I have no doubt he would have obtained the same answers. I quite agree with those correspondents who speak of the nonsense so often sent you respecting the new machine. I feel sure that many who write never sat on one for five consecutive minutes, and believe that many who abuse it gave up just when they were getting into the use of it, for I have never met with any one who had ridden a machine for any length of time but who would say with me, "Bless the man who invented them," and rejoice over the many happy hours they have experienced since becoming practised riders.

E. S.

MILLSTONE BALANCING. FEEDING BOILERS.
[113] SIR.-Kindly allow me space in your valuable
paper for a little say on mill-stone balancing.
I often wonder that no one has noticed the fact that
mill-stones are usually balanced by digging a hole in

With an hours daily practice one will learn to ride over a smooth road without falling in a week. The twisting motion on a bad rond would no doubt arise from the inexperience or carelessness of the rider or his desire to avoid all stones so as to save his machine (and India rabber tyres) from getting over them. If the curvilinear motion was in reality to keep the rider from falling he must not have been up to much and ought therefore to be free from all judgment. There is the same danger as that a bicycle rider will run into a carriage; in all such cases take care, trust in Providence. There is no fear, to one up to it little possibility, of falling in turn ing. By the ex-position of the crank in turning mechanical power may be lost, but not such as to cause any inconvenience to an adept. The "power over the machine" is not lost by any ex-position of the crank. In common turning the wheel does not rub against the Bicyles are now provided with leg-guards which do away thigh. It is only in very short turning that it does so. with all thigh-rubbing. There is no more chance or danger of the foot going through the spokes while riding than of one foot catching behind the other when running or walking. No resemblance whatever. The thrust in a bicycle is between a forward and a downward pressure. The force is similar to that required to push the chair backward with the foot resting on a low firm stool. The stepping from a moving train runs a similar danger. same danger above exemplified. A railway guard in He might slip. Very likely. The papers delight in these things. Railway accidents, &c. Place the hand on the spring somewhere behind the saddle and walk alongside. Or, if the hill is very steep, rest the elbow of one arm upon the saddle and guide with the other hand. The saddle is as good as any walking stick. "Lugging" is a word that cannot be used to the bicycle unless it is made on the waggon principle.

Bicycle riding being comparatively speaking something new, is looked upon by John Bull in his usual philosophic style. That wary gentleman accepts nothing in a hurry. Shaking his head, his story is "It may be fies "Novalis's,' statement that to become properly conall right, but I don't know yet." He very well exemplivinced of any fact you must first have disbelieved it and

M. L.

M. DE LESSEPS is reaping the reward of his ingenuity. He has been feted everywhere, and is shortly to be presented with the freedom of the City of London.

EXTRACTS FROM CORRESPONDENCE.

GAS.-J. G." says: "I do not however agree with your correspondent's remark that, Carburetting Gas' is at present not a practical process. The Commissioners of Sewers for the City were so alive to the benefit derived by such process that they ordered 1800 to be fitted to the street lamps according to the principle of Mr.J. Ridd finding a saving of about 30 per cent. by their adoption. Mr. George Glover, the gas meter Tanufacturer, also proved the benefits to be derived by their adoption, the illuminating power caused by their introduction was about 43 per cent. The Midland Railway Company have had them fitted to their pendant Iamps at the new station at St. Pancras, beside which 12umerous private firms have adopted this improved system, thus proving that your correspondent's remarks are not tenable."

CURIOUS QUESTIONS.-"J. B." says:-"In reply R. Gould's first question (page 378), there will be no defference because the ball, atmosphere, and all else on the earth's surface partake of the earth's motion," orbital" and rotatory, which consequently in no wise affect the relative motions or positions of such objects and the earth inter se. Secondly, if the word 'space' is intended to mean 'as measured on the earth's surface,' there will be no difference, but if it be taken in any other sense the difference will be so much, plus or minus, as inay be Caused by the earth's motion during the flight of the

ball."

TRADE AND COMMERCE.-"Sigma" concludes a long and elaborate letter on this subject thus: "Last and most crushing of all, we have had five-and-twenty years' experience of the working of free trade and ought now to be in a position to judge of its effects. True what is the total population now and twenty-five years ago, what the total income or even the average income of the nation? If free trade is a losing game, gradually impoverishing us, how were our railways made; where did the shipping come from which covers every sea; whence came the capital sunk in establishing colonies for our extra numbers? In fact has the supposed loss diminished our capital, and how? In London alone each year a new city is built. Walk through its bounds and count how many miles of houses there are requiring large incomes to support. Whence those incomes, whence our increasing national revenue? Take a fair view of the present and twenty-five years ago. Look on this picture and on that, and verily if these results be the inevitable consequence of annual loss and impoverishment, then, but only then, is free trade a failure."

POWER LOOMS.-"J. W." says:-"I hope shortly to be able to furnish you with drawings and description of some valuable and beautiful improvements in power looms which I am now patenting. I have had two of our principal English machine makers here to see them within a few days, including Platts, of Oldham, who appear to attach importance to the invention-and I expect to be in Manchester next week with the view of exhibiting the machines and of arranging some licenses."

REPLIES TO QUERIES.

[2637.]-ELECTRIC LOCOMOTIVE.-There is not I believe as yet discovered any practical mode of obtaining motion from electricity which is capable of being utilized. The reason being that the law of "magnetism" which seems to be the only form in which it can be employed is that the force varies inversely as the square of the distance from the magnet, which obviously reduces its available power to within exceedingly narrow limits and consequently almost forbids its use as a mechanical power.-J. B.

(2642.]-FISHING RODS.-"A Young Tyke " requires hints how to make a fishing rod about five yards long. The very best advice I can give is "don't." Such work is done by skilled workmen so cheaply that it don't "pay" to do it oneself. I have been guilty of that folly in my youthful (? verdant) days; but long ago I became a good boy and "didn't do it no more." If "A Young Tyke" had any idea what it would cost him for the mandrels, or triblets, on which the ferules must be hammer hardened (or their mouths will become anything but musical trumpets), the tools required to bore out the joints, the difficulty of making one joint go straight into the other (unless you do as I did-viz., bore them in a suitable wooden pillow-block, which I had to make for the purpose in the lathe), and the time it takes an amateur, who is seldom so much of an expert at such operations as even my humble self, to do this work he would thankfully receive my good advice, "don't" and not set to work on operations as little worthy his time as grinding specula, or lenses for 0. G.'s and eyepieces, would be worthy to occupy the time of an observer like our " F.R.A.S.", which I suspect might be more nobly and worthily employed in reviewing "The Fuel of the Sun," or viewing that luminary himself. Some advice I tender. Don't make a rod, or have one made-unless it is to be only one of several rods-so short as five yards. Make it seven yards while you are about it, and have two extra short extra butts made to it, one to receive its largest joint, and the other the next joint. You will have, supposing the rod has five joints (never have more), seven yards; six yards, and four and a half yards, quite sufficient variety for all purposes. The best kind of wood is, in my opinion, well-selected South Carolina bamboo cane. A north cane top, with a point of split jungle about a foot long I prefer to any other, but a good hard piece of south, although from its numerous channels ugly, answers very well, and north is difficult to procure sufficiently long and taper to make a first rate top a yard long.-THE HARMONIOUS BLACKSMITH. [2643.]-IRON PRISM.-Original size of prism is 3ft. long by 9in. wide, and deep plate required will be 54in. square by lin. thick.-J. B.

[2643.]-IRON PRISM.-If I understand the question aright a square prism of iron containing 2,916 cubic inches is to be flattened into a square plate of uniform thickness, containing the same number of superficial

inches, required the size of iron plate. Therefore 2016 54 inches side of square plate 1 inch in thick ness.-HARRY G. NEWTON.

[2643.]-IRON PRISM.-How can a superficies which consists of square inches be equal to solidity, which is a cubic measurement. Also what has the shape of the prism to do with the form of the plate that has to be made out of it, which latter we are told is to be square and of uniform thickness ?-J. K. P.

[2652.]-SULPHATE OF ZINC.-Extract. "Sulphate of zine, or white vitrol, ZnO,SO3 + 7HO is prepared by dissolving the metal in dilute sulphuric acid, or more economically by roasting the native sulphuret or blende, which by absorbing oxygen becomes to a great extent converted into the sulphate of oxide; the mineral is then thrown into hot water and the salt is obtained by evaporating the clear solution. This salt closely resembles sulphate of magnesia in appearance, it has an astringent metallic taste, and is sometimes used as an emetic; the crystals are more soluble in cold than in hot water. This salt forms double salts with the sulphates of potash

and ammonia."-HARRY G. NEWTON.

[2668.]-SKETCHING FROM NATURE.-At Johnson & Son's, 18a, Basinghall-street. Acetate of cobalt, 2s.

oz.; muriate, 1s. 6d.-R. SEDGFIELD.

[2677.]-HYDROGEN GAS FOR BALLOON.-Many more details are neediul to enable a truly correct answer to be given to this query. The weight of the ballon, the height of the barometer and the purity of the gas must be first ascertained. But assuming the gas to be pure, its specific gravity is 0.555 as compared with one of at mospheric air, consequently 1,000ft. of gas will support in air 41 3991b., and if your correspondent will calculate on this basis the number of feet of gas which will lift himself and his balloon the weight of which last he must assume or ascertain, the cube root of that quantity divided by 3141 will give him the radius of the spherical balloon which will contain it with sufficient accuracy for his purposes, which I venture to presume are not

practical.-J. B.

(2684.]-ENGINE CHIMNEY.-I am of opinion that a chimney 25 yards high having a flue 3ft. in diameter will do the work required by "A Subscriber."-K. [3716.]-RELACQUERING BRASS WORK.-Brass is dipped by passing it quickly in and out of the nitric acid. If the action does not take place during the first second the leaving the articles in longer only turns them black. The process should be thus to dip articles bright: Scrub them after taking them out of the soda water with sand and a brush, then briskly pass them through the acid, and immediately wash them in a pail of hold them under a pump. clean water or If not quite clean after the first dip scrub the part again, and put through the process a second time, only remember that the oftener they are dipped the more dead the colour will become. A little urine to dip articles into before passing through the acid and after scrubbing has sometimes a very good effect; eventually dry out by stirring articles up in a bin of sawdust. The quicker these processes are gone through the brighter and better the work will become.-WM. HOLMES. [3716.)-RELACQUERING

BRASSWORK.-In the first place, if the brasswork is very dirty, and not come clean enough for the acid to act on, it should be left in the acid for some time, then dipped in fresh acid; but before being dipped in the fresh acid, he must take care that all the dirt is removed before being

dipped again. The reason of the articles turning black is because they are not properly clean before dipping, the old acid will make very good pickle.-W. SEABROOK. [3726.]-CHROME BLACKS.-" For 10lb. of wool or woollen cloth," boil one hour in a solution of 4oz. chrome, 4oz. of bittartrate of potash (cream of tartar); then wash out of this solution, and boil in a solution of 10lb. of logwood for one hour.-R. R., Rochdale.

[3798, 3766.]-BAROMETER TUBES.-Without knowing of what the film is composed it is difficult to say what will remove it. But a strong solution of soda, with or with out heat, would be very likely to do so if well shaken, and some small shot inserted in the tubes at same time might by their friction expedite the process. The tubes may be filled by inserting the mercury by little and little into the siphon end and shaking it so as to allow the air to escape through it, or the air in the tube may be rarefied by heat, and if the lower end be then plunged in mercury, the air as it contracts in cooling will draw it in and this process must be in either case repeated till the tube is quite full, when it should be held upright so as to allow the excess of mercury to run off. For philosophical purposes greater care, and more adjustment and calculation, is needed than can be explained in few words.—J. B.

[3781.] PHOTOGRAPHY.-There are various

changing boxes made for the dry process, but they are all rather difficult to explain without several drawings. "P. M.'s" best plan would be to call at some maker's, The vertical developing-bath is and examine one. never used nowadays: it is a wasteful plan. If "P. M." finds a difficulty in getting the developer to flow over the plate, let him add to each pint, from one to two water. It will then flow readily, without streaks and grains of common gelatine dissolved in a little warm markings, which are sometimes difficult to avoid without

the gelatine.-R. S.

[3807.]-PAINTING STONES IN JEWELLERY.-If "T. G." will examine the setting of any coloured stone, he will find that the silver foil placed behind it is lacquered of the same colour as the stone is intended to be. Some stones are capable of having an artificial colour imparted to them by heat.-A. S. C.

[3832.]-BURNISHING PLATE.-The tool he requires is an ordinary steel burnisher, which can be obtained at any tool shop. He must rub the scratches well with it, and he will soon find them disappear.-W. SEABROOK.

[3842.]-STEEL WIRE.-I did not answer" J. R. T."

(3812) for the worst of all possible reasons-i. e. because of mine incompetence to do so. I may as well remind him, if he has not yet become tired of his fad of model church erection (by the way he had much better go to one ready built), that small bells only cost a few pence each, and what he calls wire gongs have a very disagreeable tone.-THE HARMONIOUS BLACKSMITH.

[3844.]-ENTOMOLOGICAL QUERY.-Larva of Cos mia trapezina is of a dirty green colour, with its dorsal, subdorsal, and spiracular lines white and spotted with dark green. Let "E. N." beware of the larva of Scopelosoma satellitia also. It is dark black-brown, with three

white lines on the second segment, and a white spot on the second, third, fourth, fifth, and twelfth segmenta, below the spiracular line.-AUTOMEDON.

[3844.]-ENTOMOLOGICAL QUERY.-I send for "E. N." the description of C. Trapezina (larva), as given in "Stainton's Manual," vol. 1, page 258, "Larva greenish with the dorsal, sub-dorsal, and spiracular lines white; the spots black or dark green. On oak, birch, &c., especially fond of other caterpillars," appears in May and June, abundant everywhere.-A. S. c.

[3849.]-STUFFED CANARY.-"Excelsior" can clean his canary by rubbing it with a piece of clean white wadding. Afterwards he may pound a small piece of chrome yellow and sprinkle upon it and then brush off off again with the wadding, tempering it to the shade with dry whiting.-IGNORANT.

Joseph drills a circle of holes, lin. diameter, with a small [3858.]-HOLE IN EARTHENWARE.-I think if H. Archimedian drill, and knocks the centre out, he can ile it down smooth with a medium file.-H. A. C.

[3358.]-HOLE IN EARTHENWARE JAR.-A hole may be bored by a common blacksmith's drill used lightly, and it had better be not more than in., after which the hole can be enlarged to any size with a half hammer, will quickly penetrate the jar, care being taken round file; or a sharp point, with repeated blows of a light not to strike so hard as to cause a crack, and the point to be kept moving from place to place.-J. B.

[3859.]-FLORENTINE BRONZE.-In answer to H. Joseph, I beg to inform him that to bronze the articles he inquires about, he should boil them in strong soda water, scrub them with sand, and dip them in aqua fortis; then lay them in a weak solution of the same acid, about one part acid to eight of water, into which he must put some pieces of iron wire; he will find them turn a red colour. After leaving them about two hours, take them out, dry them, and lacquer them with red lacquer.-W. SEABROOK.

[S873.]-BOOKBINDERS' GLUE.-The best method of making the above is to break the glue into small pieces; then put it into a glue-pot; cover it with cold water, and put it on the fire; stir it up frequently, and, when melted sufficient, use it hot. It must not be too A little practice will soon put you thin or too thick. right.-J. PLASTANS, 55, Dale End, Birmingham." [3875.]-BLEACHING POWDER.-Bleaching powder is made as follows:-It is a mixture of calcium hypochlorise, or chloride. It is produced by the action of chlorine gas upon moist slaked lime. The gas is passed in rooms, on the floor of which is laid the lime 2in. thick, which absorbs the chlorine, and the powder is formed. "When treated with a small quantity of a dilute acid, hypochlorous acid is liberated, and may be distilled Hereby an aqueous solution is obtained as a colourless liquid, having a peculiar smell and bleaching properties. If a larger quantity of acid be added, the hypochlorous acid itself is decomposed into hydrochloric first dipped into a solution of bleaching powder, and acid and oxygen. Hence, in bleaching, the goods are then passed through a dilute acid, whereby hypochlo rous acid is formed and decomposed, liberating chlorine in the fibre of the cloth. The bleaching effect is therefore only visible after the goods have been 'soured,' or dipped in acid." (See Roscoo's "Chemistry.")— H. A. C.

over.

[3877.)-RETINNING HOLLOW WARE.-Well clean the inside, and lay them in a bath of muriatic acid; then put some muriatic acid and sal ammoniac in and a piece of tin; hold them over a coke fire till the tin melts; then with a piece of tow wipe the tin round the W SEABROOK. inside; leave them till cold, and rince them in water.

(3911.)-MARKING.-The best way to apply printers' ink is as follows:-Get a little cotton wool; tie it up in a little soft leather; put a little ink on it, and dab it on a flat surface, either iron or stone, till it is spread even. Then dab it on the type till it is inked all over; then press the type on the article you want to mark. Writing marking ink is far more durable.-J. PLASTANS.

[3985.]-FLEXIBLE PIPE.-India rubber canvas hose pipes (vulcanized) will stand hot water, and so will leather, but if only a small size is required vulcanized India rubber will be found cheapest.-H. U.

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[3989.]-SCREW ENGINE FOR CANOE.-What does "A Young Subscriber" mean by wanting an engine for a canoe.' Either his boat is not a canoe or he wants to alter it into a steam "launch." What is really the shape of it, and what is the width? He says in his query about 2}ft.-H. U.

39

[3993.)-PASSAGE TO NATAL.-"A Cornishman will find that the "best" way to get to Natal is to take a first-class berth on board the mail steamer; the "cheapest" is to work a passage out. Seriously, there is a regu lar line of traders to Natal leaving London, and he might find a captain willing to take him for his labour and a money consideration.-H.U. [3998.]-BOOKBINDING.-Brass type would be best practice, to use single letters. for" An Amateur; "it requires great care, and a deal of Leather is all prices, from 2s. 6d. to 12s. per skin; calf and morocco are very dear; bookbinders' cloth, from 8d. or 9d. per yard.-J. PLASTANS.

[3999.]-CYLINDER.-If "Ixion" gave the size and weight of his steam carriage he might expect some one to give him the dimensions of cylinders for it. How it is possible to say what size they ought to be without knowing the work required of them I do not comprehend. H. U.

[4007.)-CURING HERRINGS.-I do not imagine Mr. Baskerville is likely to find a book containing any authentic directions for the process he requires, so I will tell him what I know about the matter. The

method of curing herrings varies with the place of curing, and the state of the herrings. At Yarmouth, off which port the shoal is in prime condition, two methods are pursued, and the fish are known by the names "bloaters" and "high-dried." The bulk of bloaters for the London market are simply taken from the boats and laid in barrels or troughs, with salt between each layer. After remaining in pickle 24 hours, they are hung up to dry in the smoking-houses, but they are not subjected to any large amount of smoke. They are ready for packing in three or four days, and are little more than fresh herrings dried, with just sufficient salt to keep

428

ENGLISH MECHANIC AND MIRROR OF SCIENCE.

them a week or so. The proper bloaters, although they are not kept in salt much longer, are really smoked over fires made of oak saw-dust (at least that is what should be used). They will keep some considerable time. The "high-dried," as their name implies, are kept in pickle till they are thoroughly impregnated with salt, and are then taken to the, smoking-room, and allowed to hang there till they are, so to speak, "tanned," in which con lition they will last a voyage round the world, and then be good. The Scotch herrings, and those caught in St. George's Channel, are made into "kippers" in large quantities, or else are treated to rather too much salt. The reason of this is, that the fish having spawned, the roe would only act as a predisposing cause of putrefaction, although, strictly speaking, this does not apply to Scotch herrings, which are turned into "kippers' for convenience in packing, especially as they are then worth as much commercially as the others, and farmers buy up the "offal" for manure.-SAUL RYMEA.

WORM-EATEN

ORGAN BARRELS.[4012.] "Pupil" will find a solution of corrosive sublimate the best cure for worm-eaten wood. It is a violent poison, and great care should be exercised in using it. The erdinary price is 6d. the oz.-SAUL RYMEA.

[4054.]-MICROSCOPIC INVESTIGATION WITH POLARIZED LIGHT.-Micro-chemical testing differs from ordinary chemical analysis only in the use of the microscope to observe the effect of reagents, and I do not know that I can give " John Barleycorn" any hints which will be of any use to him, as he doubtless is already au fait at so much of chemical analysis as applies to testing for acetic acid. Crystals of acetic acid, like most, if not all crystals, will polarize, but only in the form of crystals. If "John Barleycorn" can.persuade the acetic acid in his liquor to crystallize on his stage plate he may succeed in polarizing, but I suspect that it is usually found in so small a proportion that this will not be possible. For polariscopy objects must be mounted in balsam or in fluid (glycerine answers well for many objects), and the two glasses (that of the slide and cover), should be thin. The polarizer must be fixed in its place beneath the stage, the analyzer also being in its position, light should be thrown fairly into the polarizer by the plane mirror if possible, though the use of the plane mirror is not necessary, and the prism rotated to see if all light be cut off twice in each revolution. This is polariscopy in its simple form. Most of the objects commonly viewed by polarized light are seen by this arrangement in a ghostly kind of light on a dark ground, and if colour be wished the use of a thin film of selenite is needful. These are commonly used of such thickness as will give red and green, blue and orange, yellow and purple, the latter being by far the best. To secure the best effects it is necessary to "set" the analyzer relatively to the axis of the selenite usedthis can be got by experiment, by slightly rotating the analyzer as well as the polarizer, till the best effect be obtained. Some objects require a special "setting" of the prisms, and it is usually advantageous to try all possible positions of both prisms, as much may in this way be learned, which otherwise would have remained unlearned. Of mere beauty I say nothing-polariscopists know what this is.-H. P.

[4127.]-MOUNTING CHARTS.- Any kind of cloth will do, but brown holland is, perhaps, the best. This should be nailed tightly and well strained on a drawing board and pasted. The map or print should be also pasted and damped till it lies quite flat, then place it on the cloth and press out air-bubbles with a cloth, lifting the paper at the edge to let the air escape when needed, and when completed, leave the whole to dry, and when quite dry, cut round the map with ruler and sharp knife, and the map will come off in a perfectly satisfactory state. If to be varnished, do so with mastic varnish, whilst on the board, sizing the paper first with weak isinglass size.-J. B.

[4128.]-SETTING JEWELLED HOLES is an easy matter, practised by many a workman who possesses self-reliance and a steady hand; it ought to be particularly useful to those who live in country towns. Finishers, and English workmen generally, being accustomed to cut hollows in wheels and pinions, and hold the graver in their own hands when using the mandrel, will find it comparatively easy, and certainly not so difficult as learning to cut a clean hollow in a "best" pinion. Of course, it requires a little practice, and more attention to one or two important details. The holes are bought by the gross and half-gross unset for English jewelling ready set in brass. I believe, by sending to the manufacturer's or tool-shop the size of any particular hole or holes, they can be obtained in smaller quantities, or of different sizes assorted. I should recommend the first attempts to be made in odd pieces of brass and steel, till the hand is fairly into it, before attempting to operate on a watch plate; these, if clearly done, will serve some future time in English jewellings. The more precision and accuracy possessed, the better one is likely to suceed. Those who work in an anyhow sort of fashion should certainly leave it, and watchwork altogether, alone. The first and most important requisite is to centre the plate perfectly true to the hole to be jewelled; not that this is anything very difficult, but the accuracy of the work entirely depends upon it-the depth of the pitching is altered if not absolutely true. It must also run true in flat. The plate is chucked up on the platform P P of a tool (like Fig. 2) in wax or shellac, worked with a bow or treadle, or on a Swiss or Eng'i h mandre'. When properly centred, the hole is opened to AA (Fig. 1), leaving enough substance to support the stone; the socket B B is next turned out to receive it. This is also essential to be fitted as closely as possible to keep the jewel properly centred; for if at all loosely fitted, besides being liable to get out of centre and upright, it will give great trouble to secure the stone by rubbing down the setting, and will never make a clean job. The stone is held while being fitted with shellac on the end of a piece of wire. The tool to measure the depth to sink the jewel is shown in Fig. 1. I do not know if this is exactly what professionals make use of, but am persuaded it is something of the sort, and know it will do perfectly well. EE are two legs, of a convenient length to rest on the plate or bottom of the sink cut out for the wheel, and F à screw or round rod, fitting so tightly in the bar as to allow of its being set as a gauge, and adjusted to the hole to be jewelled or replaced. The legs and bar can be filed out of one piece, or a simple bar, if both ends are supported on the surface the plate, with adjust the

difficult part of the whole operation, as it is easily sunk too deep, or the socket made wider, thus spoiling the fitting in the frequent retouches. When it is done, the plate is turned out a little way, flush, or nearly so, with the stone, to allow the groove CC forming the setting to be made. This rim or setting should be just thin enough to be easily rubbed down-if left too thick, the stone is apt to get broken in the effort to set it; on the other hand, it is liable to be cut too thin, or spoiled. The two or three tools required for rubbing down are

N

[blocks in formation]

easily made when their purpose is known, the shape M,
edgeways N, will be found one of the most useful; no
points or cutting edges are required, but rounded off,
and burnished or polished at the acting parts. The
gravers or cutters can also be made, just as finishers
do, to cut any particular kind of hollow. To finish off
the parts D D cut away to the stone without touching
the other side, the plate is turned to the other side, and
polished. The above is for foreign work, where the
any part it rests on, either straight or curved, and
jewels are set directly into the plates; the English
jewels are in separate settings, which are fitted into the
plate, and secured by two screws-G represents one.
They are set in their settings exactly as above described,
piece of round brass fitted into the socket S S, the screw
for which purpose the platform P P is taken off, and a
T will hold it firmly, the point is turned to a conve-
nient shape, and the brass to form the setting waxed on.
The continuation of the tool at R bears simply an
English slide-rest; the platform is adjusted after it is
brought either outside, as represented, or in the socket
S. It will sometimes be found necessary, in foreign
work, where the plate has been spoiled and a jewel can-
not be found large enough, to set one in brass, and that

E. H." could favourably pursue the four times it will be found sufficiently rectified to aller of decantation. Should the supply of oxygenabove process on a small scale, as from experience I find it vields a vinegar admirably suited for domestic and culinary purposes. that is air-be deficient, much aldehyde, is produced, which from its volatility is carried off as a vapour and lost. Any aromatic substance, essential oil, or even wood vinegar contaminated with kreosote, will arrest [4160.]-KILLING MOTHS.-If "J. C. S.," or your the progress of acetification.-WALTER J. NICHOLLS. correspondent, p. 881, will try the following, I feel co vinced they will at once abandon the chloroform, hot water, carbonic acid gas, and benzine methods of killing moths. Procure one ounce of cyanide of potassium, & little plaster of Paris, and a short, wide-mouthed, sy 13in. stoppered bottle, then mix the plaster of Paris with water to the consistence of thick cream, and pour it ove the cyanide to the depth of fin.; when set, cut out two or three discs of thin note paper, somewhat larger the the inside diameter of the bottle, and press them dom on the surface of the plaster of Paris, and your appara in every respect c is complete, compact, and venient for killing moths and butterfles. It will also remain efficient for a couple of years or more, and the moths may, if required, be left in the bottle for weeks' when they will be found in a relaxed state for setting. I have just placed four large flesh flies, Mus carnaria, in my cyanide bottle, all of which were dead in twenty seconds, which is about the time required to kill a large moth. Two of the flies returned to life after reIt is desirable, maining in the bottle ninety seconds. however, to leave moths in the bottle for a couple of hours before they are taken out and set. Entomologists, in their rambles, will find the cyanide bottle a most use ful companion.-CYANIDE.

[4160.]-KILLING MOTHS, Erc.-I notice several brethren of the "net and pin persuasion" have given "J. C. S." information on this head, but neither seems to have used liquid ammonis. I find it has the great recommendation of leaving its victims beautifully relaxed for setting after death. My plan is first to stupefy specimens with chloroform and then transfer them for an hour or two into a jar (in separate chip boxes) into which has been previously dropped a piece of filter paper saturated with the liquid. For green insects it will not do, as it bleaches them. Prussic acid and chloroform make specimens too rigid for easy setting.AUTOMEDON.

[4171.]-BEES AND BEEKEEPING.-" Payne's Bee Book" is published at 20, Paternoster-row, price 4d. I don't have any entrance in the side of the cap of the hive. Let the hole in the top of the hive be about 8in. square; place on this a piece of perforated zinc, holes 3-16ths of an inch; no other sized holes in the zine should be used. I use old tea chests for caps 9in. square and 11in: deep; cut a hole in the top about 4in. square; on this place a piece of glass. No difficulty will be found in removing a cap or box of honey, as no brood will be [4178.]-MALLEABLE CAST IRON.-Consult Percy's there. Follow Payne's instructions, page 16.-J. LEE. "Metallurgy," vol. ii., on iron and steel Also the specifications of patents taken out under this head; these may be seen at the Patent Office. To render cast-iron malleable the articles are imbedded in powdered mine time; a reaction between the oxygen of the ore and the (i.e., iron ore) or hammer scale, and heated for a certain dride is formed and escapes. The cast-iron is thus more or carbon present in the cast iron is set up, carbonic anhy dented by a blow from a hammer. Inferior tools, &c, less decarburized, a more or less soft iron is produced; it is not truly malleable, it will not weld, but may be ASSOCIATE OF THE ROYAL SCHOOL OF MINES. [4194.]-PHOTOGRAPHY.-STAINS, &c.-"W.G.C.' made in this way are termed "run steel" articles.-A can remove the stains produced by the silver solution by means of hyposulphite of soda or cyanide of potas sium.-AN ASSOCIATE [4198.]-GAS COOKING.-There is a mistake in the MINES. statement of quantity of gas consumed. It should be for a small fruit pie, from 2ft. to 24ft. for a large pan potatoes, or other vegetables, 2ft.-not 2ft. per lb. weight

[graphic]
[graphic]

OF

as stated.-THOS. FLETCHER.

THE ROYAL SCHOOL 07

as if it were a larger stone. The holes without end-
[4204.]-DRAWING PENS.-In reply to "T. M.," his
stones are set from one side of the plate, and those with
failure in the use of his drawing pen may result from
from the other, or that on which the end-stone is
screwed on. H is the tool for sinking the screw-heads,
I and L the end views, which, I think, can be made to three causes-viz., first, from a bad pen; secondly, fr
beginner, I would advise him to purchase a bottled
ent sufficiently with a slitting-file; it can have a collet the ink being too thin; and thirdly, by allowing
fixed with a screw to sink any depth, or a shoulder much space for the flow of the ink. As he is one
this will save him much time and trouble, it being al
turned on the drill itself. The magnetized balance is
sad job, and I can only confirm what H. Chance has liquid drawing ink, which will cost only one shill
said, with the addition that it must not be placed in a
drawer with any tools, or any other parts of watch work. ready for use when required. Now, as to the use
of the pen is clean and bright (remember, if it is dirty
It is much to be regretted that nothing has as yet been pen. When you are going to work, see that the
discovered that will demagnetize steel so completely as
is required in horology. It would form a fair field of the ink will never flow properly), then open the pen to
research for our electricians. "I cannot understand why very slight extent, and with a pen, or still be
the watch should lose so much. If the hairspring were
infected, two or more coils would adhere together,
which would either make it gain or stop it altogether,
It must be a horizontal watch, and both the wheel and
the cylinder magnetized it very strongly magnetized,
would stop it. If such should be the case, there is no
other resource but to replace the affected parts. - NOBODY.
[4156.]-AQUARIUS.-Try a work by Sir William
Fairbairn on water-wheels. I believe he is the best
authority.

sewed.-J. G.

Messrs. Spon are the publishers, price 4s,

[4156.]-BOOK ON WATERWHEELS.-Fairbairn's
"Mills and Millwork" is perhaps the best.-AN Asso-
CIATE OF THE ROYAL SCHOOL OF MINES.

[4159.]-VINEGAR.-I submit the following method
for the preparation of vinegar to "E. H." (No. 4159,
p. 358), known as the rapid process, now followed on the
Continent to a extent. A mixture
sisting of 1 part of alcohol at 80 patut is made con
water, and 1-1000th part of a ferment, such as vinegar,
honey, or the must of beer. A barrel with holes drilled
in the middle and upper part, is then packed with twigs
or shavings of beech, which have been soaked in strong
vinegar. The mixture above mentioned is then warmed

camel-hair brush, put a small quantity of ink in the pen, then close it till the points just touch, when is ready for use. After a little practice he will difficulty whatsoever in using it. When he comm universal scale, &c., let him, if he can, call on me, wh to study the proportional compass, diagonal s may need.-THOMAS S. O'CONNOR, Wrexham. I shall be most happy to give him all the instructions

[4204.]-DRAWING PEN.-As I understand "T. M required his fault lies in using too much liquid ink, instead of buying it in cakes and rubbing it for himself as

The ink sold in bottles is gummy, and will not make fine his pe continually (using a camel's hair brush for this purpos as the great merit of Indian ink lies in its power of dry. ing quickly.-R. P. T.

"T. M." complains, and many others that he probably [4204.]-DRAWING PEN.-The difficulties of which course of Binn's admirable work on "Orthographic Proknows not of, will be removed by reading the secon and eng neering drawings. Bee advertisement in the columns of

our ENGLISH MECHANIC.-A DRAUGHTSMAN.

[4204.]-DRAWING PEN.-Take care to keep the pen

to 75% or 80°, and made to trickle slowly through the clean, drawing a bit of paper between the points when

The

thus exposing an immense surface to the air.
temperature of the fluid rises rapidly to 95 or 105°, un-
less too small a quantity of air be admitted. When the

there will then be no difficulty.-J. B.

a

it;

[4214.]-SALMON TACKLE.-"Doncastrian "will find

depth. Sinking thej ewel to the exact depth i the most mixture has been passed through the barrel three or very broad streams 21ft, or 22ft, may be requisite; but

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the smaller rod is enough for any average man to manage properly. A reel about 4in. in diameter, with about 80 or 100 yards of eight-plait dressed silk line; a gaff, with a handle 6ft. long, a few different kinds of flies, and a basket into which to put the fish, will complete his equipment. As to his own wearing apparel he should get a pair of waterproof boots with tops to come above the knee. I would not advise him to make his rod: he can buy one cheaper and better, because the wood will be more likely to have been properly seasoned; indeed, I doubt very much whether he can buy the wood in a fit condition. One bit of advice I will give him. When the fish has taken the fly, don't strike till he has really got it, or till he has turned to go off with it; then strike, and strike hard, so as to be sure to drive the hook in

over the barb. 50 per cent. of fish are lost through

neglect of this point.-J. McF., Stobo.

[4229.]-WASTING MACHINE.-I herewith send you a sketch of the most simple washing machine I have seen. I think perhaps it may be the kind of thing your correspondent J. W." wants. I shall be happy to give any further information on the subject that may be required. The cost if made by a carpenter would be about £2 10s.

DESCRIPTION.-Fig. 1 is a section through the middle of machine. Fig. 2 is a side view. In each case the dotted lines represent the beater. Figs. 3 and 4 are front and side views of beater. The bearings are cast in gun metal, and the beater is made of ash.

FIG. I

MODE OF USE.-Place the beater in its place and put the clothes in each side with enough soap-water to half fill the machine, then work the beater backwards and forwards.-F. M.

[4231.]-HAND PLANING MACHINE.-I send engraving cut out of Cook's catalogue. It is described thus: "To plane 12in. long, 8in. wide, and 6in. deep, self-acting cross slide; screw clamps; screw keys; and six tools; mounted on a cast iron base for handwork, only £38 10s. Without self-acting cross slide, less £7 108. Parallel vice with circular plate £7 10s. Ditto with out circular plate, £5."-J. K. P.

[4233.]-BICYCLE BREAK.-The ordinary form of It does not break is the proper one for rubber tires. appear to wear or injure the rubber in the slightest degree.-THOS. FLETCHER.

[4234.]-SEWING MACHINE IRONWORK.-Reduce with the file any very rough parts (such as what I would call the "seam" of the casting), and give it two or three coats of coach-painters' varnish. Price, 1s. 6d. per pint. Proved.-AQUILLUS.

[4237.1-VINEGAR.-Let "Grocer" do nothing so simple as to try to turn wine into malt vinegar: one advertisement in your columns would secure him sufficient orders to dispose of a large quantity of his genuine white wine vinegar.-W. H. C.

HAND PLANING MACHINE.

[4238.]-KANSAS.-The fare from London to Liver-
pool is 12s. 6d.; from Liverpool to New York, by steamer,
£6 68.-by sailing vessel, £4. Passengers can also be
booked from London at the same rates. Railway fare
from New York to Kansas City is £3 16s. 6d. While on
this subject, I would say the society mentioned in my
letter, the "Working Mens' Co-operative Emigration
Company," whose office is at the Mission Hall, Darling-
place, Mile End-gate, will be sending out a party about
the middle of August.-J. D. ROGERS, Hon. Sec.
[4241.]-OIL OF BRICK.-This is obtained by soaking
common bricks in oil, and afterwards distilling the oil
from them at a red heat in an iron alembic.-HARRY G.
NEWTON.

[4244.]-EQUISONANT FLUTE.-If "S." can call at
35, Percy-street, Tottenham Court-road, he will obtain
the information he seeks; or he can write to Jno.
Clinton, Esq., at the above address. If he is an advanced
player, and aims at proficiency, no matter what flute he
selects, I strongly recommend the daily practice of
Boehm's "Twelve Grand Studies."-SABLE.

[4248.]-SILKWORMS.-The length of filament
usually produced by a cocoon is about 300 yards, although
in somewhat rare cases this has been doubled. For one
pound of silk eleven or twelve pounds of cocoons are re-
quired, about 250 of which go to a pound, therefore an
ounce of silk would require about 180 cocoons. The other
information may be obtained at Covent Garden Market.
-HARRY G. NEWTON.
FIC.2

FIG.3

FIG. 4

14248.]-SPARK FROM INDUCTION COIL.-The only way to find the length of spark it will give is by experiment.-THOS. FLETCHER.

read such a subject as the calculus without assistance -R. P. T.

[4250.]-MUSHROOM CULTURE.-After the horse manure (or droppings) has been kept in a heap for about a week or ten days, and heated to a certain extent, have it spread out in the open air to sweeten and drive off the ammonia. If there is a hot sun and nice drying then put it together to make your bed, treading the wind, three or four hours will be sufficient. You may manure thoroughly all the time (you cannot make it too solid), until you get a depth of 18in. to 2ft.; upon this place your spawn. Cover this spawn with good damp mould to the extent of about 2in. Again tread this, and make it tolerably solid. By this simple method on a bed 7ft. by 3ft. in an ordinary stable or outhouse at a temperature of 550 to 60°, I can produce and cut mushrooms of the finest quality.-T. PEARSON.

[4253.]-TODHUNTER.-Todhunter says (page 10) "If r denote the circular measure of four right angles, the circumference is 2 r.. the circular measure of 2 that is 2." Hence we see that four right angles is

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the circular measure of two right angles is, that is 3-14159265 &c. &c. The symbol is used to express the ratio of the circumference to the diameter, because the value of cannot be stated exactly. It will now be seen right-angles, and that Todhunter is perfectly consistent. that 314159 &c. (or ), is the circular measure of two -J. R. RENDALL.

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[4253.]-TODHUNTER.-"The constant ratio of the circumference of a circle to its diameter is usually denoted by the symbol ; hence the ratio of the semi-circumference to the radius will also be denoted by , and the ratio of the quadrantal arc to the radius by -Hymer's Trig., p. 4. Note: The semi-circumference is 180°, or the measure of two right angles.-ANON. [4256.]-NEW VELOCIPEDE SADDLE SPRING."T. L." in your last issue speaks of a bicycle he has seen with the saddle spring carried beyond the guide socket, about 6in. over the front of the guiding wheel, the hind wheel being very small. I beg to inform him that it is not patented. The makers are Orme Brothers, Wolverhampton. The advantages are that the rider can sit directly over the crank, and so obtain very high speed with less exertion than when the saddle is further back, the small hind wheel dispensing with the drag which larger ones have for fast riding. I believe it to be the best principle of construction yet adopted. - THOS. SMITH.

[4264.]-MATHEMATICAL.-Multiply together the height, the breadth, and the mean depth, which in this case is half the height. Multiply again by 62 (the number of lbs. in 1 cubic foot) and divide by 2240 to reduce to tons, thus:

=

111078
2240

=1

18 x 11 x 9 × 62}
49 tons.
2240
What is called the "centre of pressure" is at the
depth, or 6ft. from the bottom; and is where you should
apply a beam across a sluice to support it in the purely
theoretical case of having that beam and nothing else
for a support, and it is actually the place where some
sluice gates are hung on horizontal pivots, so as to turn
over of their own accord when the depth increases be-

[4250.]-ALGEBRA.-I will endeavour to give A.
Davies as little work as possible; but he must under-
stand that he will now and then come across passages,
which he must omit through not understanding the
principles to which they refer. This will not often beyond a certain point.-J. K. P.
the case however, and if I knew the edition of Tod-
hunter's differential calculus which he intends to use, I
could easily point out anything which would be better
passed over on a first encounter. It is only necessary to
know algebra as far as quadratic equations, with a fair
knowledge of the theory of indices. The student must also
be able to use the binomial theories, though he need

not trouble himself with the proof of it. He must also
read the chapter on exponential and logarithmic series
In trigonometry, he may omit the chapter on the pro-
portional parts, and chap. xvii., &c., to the end of the
book. Conic sections he ought to be well acquainted
with. I mean analytical conics of course: geometric
conics will not help him at all. As almost all the ap-
plied examples of the calculus are taken from conic sec-
tions, he will find it almost impossible to proceed with-
out a good knowledge of this branch of mathematics. I
must warn him that he will find it exceedingly difficult to

[4271.]-TRIGONOMETRICAL DIFFICULTY.

3 (31og. 3-1) +

- 9 log. 3-3 +

=

8 5

5

(4 log. 3-2)

(2 log.) + 13

5

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= (9+16-5)

60 +32 + 25

log.

117

2

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