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The next operation in water analysis is to determine the amount of "skeletons" of sewage, as Frankland calls the nitrates and nitrites :-Take one pint (7000 grains), and evaporate to 4oz., add silver sulphate to precipitate the chlorides, filter and evaporate to a very small bulk; this is placed in the cup of the tube C in the figure, and admitted under the stopcock; concentrated sulphuric acid is then admitted, and the mixture gently agitated, nitric oxide is expelled, which may be ac urately measured, and the amount of nitrates calculated. The nitrates vary much in quantity, sometimes being absent altogether, and at others existing in quantities as much as 20 grains per gallon.

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it into two portions; treat
the first directly with the
bichromate, and the second
portion must be treated
with zinc, and afterwards
with bichromate; the first
will give the amount of
iron as protoxide, and this
amount if subtracted from
the amount of the second,
will give the peroxide.

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have a = - a 1 times a = a, when o is treated as if it were a real number or magnitude. But it would not suit our purpose to follow such a plan, because we should never obtain above one root to an equation, no matter of what degree it might be, whereas it is well-known that what are called the "paradoxical" results, give us roots that answer the conditions of the questions in which the equations are involved. Thus: A number squared with 12 added, is equal to seven times the number; what is the number? Here

Query 2351.-It would be almost impossible to give 2-7 x + 12 = o, divide both sides by x 4, and a test for alcohol in any we have 3 = 0. Hence x = 4, and x = 3 are kind of liquid; the tests the roots of the equation, either of which numbers must often be modified to will answer the conditions of the question. If the suit the liquid. If Al- above equation be tested in the way that a2 - ab = cohol" will give the liquido was treated, we get the same apparent paradox. in which he suspects alco- Thus, let = 4, and x4 = o. Multiply both sides hol, I may perhaps help by x-3-ie., in reality by 1, and we have 2-7x+ 12= 0, divide this by x-4, and we have x-3= o, or x = 3. T. BROWN.

him.

"Rudis," query 2'56, may extract the gold from the sand by boiling it with aqua regia (nitrobydrochloric acid) Chloride of gold is formed, and may be obtained by dissolving in water and crystallising. If, however, metallic gold is wanted, it may be precipitated by adding ferrous sulphate, which threws down the gold as a black powder, which may be fused with borax into a button. GEO. E. DAVIS

LATHES.

There is

SIR,-I am sorry to have been the means of promulgating the grievous error that Mr. Bennett, who invented the die-chuck I sent you two weeks ago, had ever worked in Mr. Evans's shop. I have not seen Mr. Evans since, but am satisfied that Mr. Baker must be better informed than I. Though Mr. Evans is not able to claim the distinction of having been Mr. Bennett's employer, there is no reason why he should not have some credit given him in a matter of much greater consequence, and which he does not seem likely to get. In your number of April 8 you give a picture of Mr. Salt's lathe, which you say was "chiefly made at Saltaire, but was finished by a London maker I happen to know that a great part of the lathe which was made at Saltaire, and which came to Mr. Evans's. 104, Wardour-street, Soho, London, to be "finished," "Basin," query 2192.-1 suppose the quantity of was put on one side, and entirely re-made. ammonia contained in the sulphate is what "Basin " no wonder that it cost a lot of money, as everything requires. that could be was made of steel. The whole of the Place 17grms. of the sulphate in a small distill-slide-rest, for instance, is steel, and the "bright set of ing apparatus, with an excess of potash solution, engine-cut wheels" would have been steel if they and apply heat; conduct the ammonia, which is could have been cut at any reasonable price. They liberated, into 50cbc. of a normal solution of sulwere done in the machine of which a drawing forms phuric acid. When all the ammonia has passed over, the front page of No. 258. The "screw headstock," or colour the normal acid with litmus, and neutralise poppet head, has the "base slide" arrangement, with normal alkali, noting the number of cbc. used; which, it it has not been altered since I last saw it, the number used subtracted from 50 gives the per- has the desirable faculty of going over on the wrong centage of ammonia. If the sulphate is a very impure side-viz., away from the workman, thus turning cones variety, and it is required to know how much sulphate had anything to do with the overhead motion further biggest at the little end. I do not think Mr. Evans it contains, take 66grms., and proceed in the same manner only conduct the liberated ammonia into 100 than making some alterations to order; and I hope cbc. of normal acid; the number of cbc. of acid that his mind is not oppressed with the recollection of actually neutralised represents the percentage of ever having made for such a lathe such a chuck as the face plate with four dogs sticking out of it, which is shown on the floor in the picture.

sulphate of ammonia.

To" Discipulus," query 2197-1. Dissolve 1grm. of the sample of salt-cake in 100cbe, of water; then dissolve 122 grammes of barium chloride in a litre of water, and add to 5 cbc. of the salt cake solution until it occasions no further precipitate. A small filtering tube must be frequently used, as the end of the precipitation may be overstepped. Each cbc. of solution is equal to 0. 96 SO3, or 0.01 grm. S03. 2. He may separate barium from strontium by exactly neutralising the solution, and adding potassium bichromate (K2 Cr2 07); the barium is precipitated as an insoluble chromate of a yellow colour, whilst the strontium lemains in the solution. The barium chromate is decomposed by acids. 3, Dissolve 17 grains nitrate of silver in a litre of water; ench cbc. of this solution indicates 0-00355grm. of chlorine To determine the amount of chlorine in any solution, a few drops of potassium chromate are added, and then the silver nitrate solution, until after well stirring a blood colour is still manifest. The number of cbe used x 0.00355 gives the amount of chlorine. 4. Standen's patent manure, which is a bone phosphate, need only be examined for soluble phosphates and ammonia. Ammonia does not exist in the manure, but is formed by the decomposition of the gelatin. Estimate the phosphoric acid thus:- Dissolve 69 grammes of uranium nitrate (crystallised) in 100cbc. of water, each cbc 0001grm. of PO2. If the P3 Os is required, 9:34 grammes must be dissolved in 100cbc. of water. Bring a known weight of the manure into solution, filter and add a solution of acetate of sodium and acetic acid, then add the uranium solution until a drop taken out produces a brown coloration when placed in contact with ferrocyanide of potassium. The number of cbc. used, multiplied by 0.001. gives the amount of phosphoric acid. To estimate the ammonia, he must add caustic potash, or soda lime in a distilling flask, and lead the ammonia into normal sulphuric acid; 17 grammes of ammonia will neutralise 100cbc of the normal acid.

J. Crompton, query 2271, may purify his acid by distilling it in a glass retort. Of course he cannot cheaply ree over the nitric acid from the nitrates, which result

from the action of the acid on the metal.
"Izgitzar," query 2279, is referred to page 605, Vol.
X., for a method to estimate the amount of organic

matter in water.

"J. N. from the North Country," query 2325, must take 10grms. of iron ore, and dissolve it in hydrochloric, and proceed with the bichromate of potassium solution, as I have stated on page 605. Vol. X., save that he must, after bringing the ore into solution, divide

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J. K. P.

APPARENT PARADOXES IN EQUATIONS. some time ago, and which has elicited several answers, SIR,-The "apparent paradox," given in a query but which appear not to be satisfactory to the proposer is simply one of those difficulties which present themselves to the student when advancing over the first stepping stones to a knowledge of the theory of equations. As it is an important subject to the student of mathematics, and may have been a troublesome one to many of your readers, you will perhaps allow me a little space to endeavour to explain it.

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made of a cigar box placed over its mouth, and In a wide-mouthed glass jar, having a wooden disc pendant from the board, are three copper wires coated with gutta-percha, with their ends turned up, supporting a hollow ring or cylinder of amalgamated zinc of in. thickness, the lower edge resting on the turned up ends of the pendant coated wires, the guttapercha covering of the wires preventing contact of the zinc and copper. The zinc cylinder is connected to a wire of copper or platina passing up through the board disc, and through a binding screw.

Suspended from the centre of the disc of wood and without touching it, is a piece of platinised silver hanging plumb in the centre of the cylinder of zinc, (sheet) rolled up, which is connected with a binding screw on the top of the wooden dise by a piece of its own metal; these two connections and binding screws constitute the two terminals.

The jar is to be filled to or its weight with a mixture of oil of vitriol of 660 by Baumé, 1 part, with 12 parts water, to not quite cover the zinc or platinised silver. The parts of the zinc and platinsed silver exposed above the surface of the acidulated water should be coated with well-boiled coal tar to protect it from the gases freed from the reaction and oxidation.

When not in use the two metals can be lifted out by meaus of the wooden disc to which they are attached, and dipped into water to wash them.

With this battery as powerful a current can be had as is compatible with durability, although more powerful currents can be obtained with bichromate of pottasa batteries, but they are of short duration and varying power.

I would recommend that the cylinder of platinised silver be corrugated to obtain more surface of exposure to the acid in a small compass.

Appended is a sectional drawing of the apparatus, with descriptive reference.

A, amalgamated zinc cylinder; B, platinised silver cylinder, which should be corrugated; C, copper wires coated with gutta-percha, for holding zinc cylinder; D, binding screw terminals: E, wooden disc for supporting the cylinders; F. glass jar; G, the top line or surface of acidulated water.

AMERICAN SUBSCRIBER.

If ab, and both sides be multiplied by a and 2 taken from both sides we have a2 b2ab62, and if the proposer chooses to take ab from both. sides, we have a b2 (a - b) = abb2 (a Divide both sides of these two equations by ab, and we have a + b = b, or ao, and a+b-1b-1 or a= o, or as the proposer put it. 21. which reduces to 1 = 0. Now, this anomalous result, a = o, is exactly what every one conversant with the theory of equations would expect, because it is well known that if any equation, say of three degrees, as 362 x = 0, be produced by the multiplication of three factors. as xb, xb, and x, of which one is the monomial x, then o is one of the roots of tht equation. The equation proposed by "U. B." is simply the equation aabo in a disguised form, of which the two roots are ab as assumed, and a = 0. But this is no answer to the querist. It is required to be shown how the value ao arises in an equation, which was built up with the value ab assumed. Now, since ab, then a-bo, and if both sides be multiplied by a we have a (ab) = o, because o Many attempts have been made to accomplish this taken any number a times is o still feat, but all of them have proved more or less useless. vide both sides by ab, we obtain a = o, because o Now, if we di- The prevailing idea is that of having a valve at one divided by any quantity can never make any more side of the pipe near the top, to be operated upon by the pedal key; but the great objection to this is, that than 0. the same quantity of wind which causes, say, the C Now, this arises from the fact that when we multiply ab by a we treat ab as if it had some real and pipe to speak, will prove too much for it when called definite magnitude, instead of its true value and inag-overblow, or else give a different or uneven quality of upon to sound C sharp, thereby causing it either to nitude, viz, o. Whereas, on the other side we treat o at its real value, o. If we assign to abits real value, than we shall have a times o, or o on the left hand side of the equation, as well as on the right.

If we treat o as same number or magnitude on both sides of the equation, then the paradoxical result vanishes thus: a-bo, multiplying both sides by a. we have a (a - b) = o xa. Divide the first side by a-b, aud the second by its equivalent o, then we

ORGAN BUILDING. in the subject of organ building I take the liberty of SIR,-As many of your subscribers seem interested sending you an idea of my own for making one pedal pipe do duty for two.

sound.

stated, but also to have 2 feet and 2 pallets to each pipe, Now my idea is not only to have the valve as before is it is evident that by so doing the wind for each note could be regulated to a nicety.

lu fixing the pipes, one foot would be placed over ne hole, and the other higher, the action would then be thus: over the one a semitone down, say, the C pedal key, the air would be admitted On pressing

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TRISECTION OF AN ANGLE. SIR,-I beg to forward you herewith two specimens of the trisection of an angle by an original method. I should much like some of our mathematiesl correspondents to try the style of doing it, and (if accurately worked) I have no doubt they would arrive at the exact required result. The same letters apply

to both figures. Let A B C be the angle to be trisected. On AC mark off any three equal distances BI, 1H, and H G. draw the arcs FI, EH, and D G, bisect the angle ABC by the line K B, cutting E Hin L, mark off the distance H L on the are D G from the point G, the points being M N and O, join O B, cutting FI in P from point Don D B, mark off DQ equal to F P,

acquainted with all the top es which may have
interested them. Intercommunication between secre-
taries would also prove useful in matters which could
not be referred to in the pages of the MECHANIC. I
might enlarge on the many advantages to be derived
from such associations, but refrain until my fellow
subscribers have had an opportunity of expressing
D. WILLIAM KEMP, Leith.
their views.

THE ENGLISH VELOCIPEDE ON A NEW
PRINCIPLE, AND OUR ENGLISH ROADS.-II.
(Concluded from page 65.)

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24 DISHED WHEEL

A

X

enjoy from the reading of your MECHANIC, and I wish you every success in your arduous and praiseA THINKER, worthy undertaking.

THE "MACCLESFIELD" VELOCIPEDE. SIR,-Having been inundated with letters requesting measuements and plan of this machine, I purpose answering all the correspondents through the medium of your admirable paper. Let it be taken for granted that it is the least fatiguing velocipede I ever mounted; can turn any corner, climb any hill, and stop instantly anywhere in coming down hill, not easily upset, very strong and firm, also free from danger.

24IN

C

A. Centre pin, holding front axle.

SEAT

B. Front axle, 36in wide outside measurement.

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C. A block of wood to raise the plank 2lin. from the ground, as the front
must be 3in. higher than behind.
E. Steering handle.

F. Hinged fork to hold steering handle in its place when going down hill.
X. Ash plank, 4ft. 3in. long, Sin. broad, 2in. thick.

SIR,-Respecting the proper use of the velocipede, I will just mention the frequently imprudent use of the same by those who are strangers to it. A friend was once using mine for the first time, and not being very strong, he almost killed himself by over exertion; let this be a warning to others. The use of the velocipede requires a training by all, especially those who are not strong. Let the following points be particularly observed at first, viz. :-Avoid trying to go fast, avoid going a long distance, and up steep hills; practice only when the roads are in good order, aim at learning the action and at going slowly; when the muscles are being sensibly developed, relinqish the exercise as soon as possible, so as to avoid being fatigued. Go on in this way for a few weeks and you may then increase both your speed and distance. Going at it recklessly at first is the fruitful eause why some have turned away from the velocipede in disgust, and now hold it in contempt because, they say, it is harder work than walking; whereas, had they observed the above rules, and had some patience, they would undoubtedly have come to the opposite conclusion. I have considered the machine, and also its worker. I now come to the subject of roads. These three parts are included in the velocipede question. Since the railways were made and our high roads have been comparatively deserted, the question arises whether they could not be made of greater use than now? I think so. Let the Legislature be petitioned, and an Act of Parliament obtained to utilise our great high roads. Let them be asphalted, or made waterproof THE FIGURE AND MOTIONS OF THE EARTH. on the suface by some cheap and durable material, in order to avoid mud in wet weather; velocipedes could then be used whether fine or wet; or this plan: let them be divided into three parts-one side of the road for foot passengers, the middle for ordinary traffic, and the other side-say about three yards wide-appropriated exclusively for the use of the velocipede, let this part be asphalted or paved with well-dressed and well-set thick flagstones. Such a road as either of the above would be the solution of the velocipede question; just in like manner as the railroad was the solution of the use of the steam from point Q with centre B, describe are Q R, the dis-engine as a locomotive. But, it may be said, incurLauce L H will then be found exactly to trisect the ring such a large expense in forming the roads as are QR in points S and T, join S B, TB, and the angle above suggested would never pay. In answer, I would is trisected. I wish you success with your new say, let the velocipedes be taxed. I think no one who volume! VIBRATOR. has a velocipede will object to be taxed, provided he could get a perfect road to run upon at all times.

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All velocipedes require good steering, which is only acquired by practice. This machine is constructed upon the principle that the driving wheel shall bear all the weight of the rider, so that the front wheels are only needed to steer by and hold the frame steady. No springs are required, nor is there any jolting. If the front axle is taken away and a small steering wheel put in its place, it would form a first-rate THOS. STANWAY. bicycle, which could not upset, because the levers would catch the ground.

-THE EARTH'S ROTATION.

SIR,-My object in writing a series of letters on this subject is not to establish any new theory, but to so far combat old ones as I deem (and I trust I shall show) are not founded on fact, but are called in to existence from necessity, as an aid, to some extent, in establishing other theories. I think no one will de ny that any theory not founded on fact is injurious, in so far as it not only takes the place of what is in accordance with fact, but by a cursory examination tends in some measure to confirm or represent error as truth and so far is positively injurious to the best interests of society.

I propose with your consent to alter the form of my succeeding remarks on this subject from what ap peared in the ENGLISH MECHANIC, Vol. X, page 510, and propose to consider the whole matter under the separate heads, Rotation, Revolution, Parallax, and In the meantime, while the above suggestion is Gravity. These subjects are so bound up together by being ventilated, let us consider if the present system the modern system as to be absolutely inseparable one of mending our roads can be improved. I think that from another. And in connection with these subjects it will be admitted by all that rain is the primary I also propose to notice Mr. Proctor's arguments on cause of our roads getting out of order, from the fact each as I proceed, as I deem this plan more precise and that it softens the roads; from this, it will be clear better connected, and of course will be better underthat everything that can be done to obviate the stood by the majority of your readers. I will, theresettling of rain on the roads is essential to their dura-fore, without further prefatory remarks, proceed at hility. I entirely agree with Sir Joseph Whitworth's once to notice the Theory of the Earth's Rotation. remarks, as quoted in the ENGLISH MECHANIC of March 11. The barbarous mode in which our roads are mended is beyond all comprehension. What is the cause of the numerous holes (which are so many lodgments for water) on some of our roads? I was under the impression for some time that it was entirely In the editorial article, "Ourselves and Our Sub- owing to a weakness in the foundation; it may be so scribers," our talented Editor states the fact that the in part, but I believe the cause is also, and more **ENGLISH MECHANIC subscribers may be considered probably, owing to the crossings of the wheel tracks as members of a vast mutual improvement society before the road is set. If a good steam roller were who consider it a duty or a privilege to instruct used immediately after repairs, aud the road set or each other." This is so in accordance with my views hardened, we should not have such holes and uneventhat I am prompted to make one or two suggestiousness as (to our disgrace) is so common in these enwhich I have withheld until the present, but now con- lightened days. sider it a fitting opportunity to bring under the notice of our subscribers, and to hear their opinions.

science, and art, both at home and abroad.

1. That in large towns where there may be from ten to a hundred subscribers, it would be productive of much good if they could be brought together periodically-say monthly, to discuss the many topics which have been under review in the MECHANIC during the preceding month. Then one of their number to communicate to this journal anything which might be considered of sufficient importance, for I have no doubt the Editor would willingly allocate a small portion of his valuable space to report the transactions of "The ENGLISH MECHANIC's Science and Art Societies." Speaking for myself, I have derived so much pleasure and instruction from friendly discussions with the few subscribers I know, that I conceive, if done on the large scale, it would prove highly beneficial.

2. It would be a means of increasing the circulation of the ENGLISH MECHANIC by friends being introduced to the meetings, who would doubtless become interested sooner or later in the proceedings, and would of course take in our jourual.

3. Engineers and others who have occasion to remove to other towns, either to new situations or iu the way of business, would find a "society of friends " who would sympathise with their every thought, and

But, I fancy I hear a road surveyor say, But what of
the expense? Who is to find the money to repair them
in that expensive way? In answer, I would say,
going on with the present system of repairing our
roads is carrying out the old maxim of being penny
wise and pound foolish. I say, repair the roads in
the way suggested, and I believe in a short time it
will, perhaps, not take half the expense to keep them
in good order.

I have adverted to the subject of roads because it is
so intermingled with the subject of velocipedes that
the one cannot be divorced from the other; in fact, the
velocipede question is more a question of road than
one of mechanics, and I trust that very soon wiser
counsels will prevail with those to whom we look for all
progress in this respect, and I anxiously hope that, ere
long, the roads of this kingdom will be in such a
as greatly to enhance and en-
state of excellence
courage the use of that most noble machine, the
velocipede, which, rightly used, tends so greatly to
promote the health of our people, to give vivacity to
society, to add vigour and stability to the State, and,
to bring honour and glory to our country.

I thank you for the vast fund of information which
I from week to week receive, and do from day to day

We are told by modern astronomers that the earth is nearly 8000 miles in diameter, which being multiplied by 31416 gives an equatorial circumference of 25132 miles, which (performing one rotation every 24 hours) gives a surface speed of 17 miles per minute for any object on such surface, but continually decreasing as we approach the poles. Our Arctic voyagers, so far as I am aware, say nothing about perceiving any difference as they approach the Arctic Circle, as it is called. If, therefore, we examine this theory closely and assist the elucidation by a diagra n, we shall find the whole idea to be simply absurd. Let N represent the north, and S the south pole. It is plain that the centrifugal force at the equator A B must be proportionately greater then it is at CD, and would amount to nothing could we esch the poles themselves (N Thus, while or S). body on one part of the earth's surface is rushing through space at the rate of 17 miles per minute, a body on the polar surface would be stationary, or nearly so; a matter it is necessary to prove before we can correctly say that the earth rotates about its axis, as it is said to do.

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miles, and if he remained up one hour, to E, or 1000 miles, and so in proportion to the time he remains suspended in the air.

need bardly say this is not so, and the idea is only tenable on the ground that the atmosphere is inseperably connected with the earth, that the atmosphere moves with the rotating earth at the same speed and in the same direction; but I am not aware that it has yet been proved to do so. How can that which floats on its surface from all points of the compass be said to be a fixture and invariably move with it? But the double motion of the earth, that is its rotation about its axis, and its revolution about the sun upsets this argument entirely, for if the atmosphere is a fixture considered in connection with the earth's rotation, what is to become of its fixity in connection with the revolution of the earth round the sun, at a speed at which I should think even Mr. Proctor stands aghast, and which I shall eventually show is a manifest absurdity-an utter impossibility.

Even the commonest observer must know that much of the strong wind we experience in this country at certain seasons of the year is from the west, that is in the same direction as the earth's rotation, and suppose the day on which we make our observation is a stormy one, he will find the clouds carried past him at the rate of from 50 to 60 miles per hour, or near one mile per minute. But the earth is said to be accompanied in its rotation at a speed 17 times as great as our storm clouds by the air in which these same clouds float; how can this be? If it really is so, the clouds must be travelling at a speed of 18 miles per minute, inasmuch as they rush over the earth's surface at a speed of one mile per minute, while the earth rotates at 17 miles per minute, which together make 18 miles in one minute of time.

Again, if the earth rotates from west to east, and a storm comes from the south at a rate of one mile per minute, and the peaks and valleys of the earth's surface are passing at a speed of 17 miles per minute, what would become of us? The centrifugal force generated by the earth's rotation and the wind would cross each other to such an extent as to derange the whole order of creation: the effect must be precisely the same as of two bodies striking each other at opposite angles.

If the atmosphere is really a fixture in connection with the ea th in its rotation about its axis, and that both proceed from west to east at the speed just named, how shall we explain away the first and most simple principles of motion? A railway train would not be able to proceed at the same speed from east to west as from west to east, because of the current of speed assumed by the earth in its rotation. For instance, if any one will try to alight from a railway train when in motion, he will find he must alight by springing in the direction of the motion of the train, or he will be brought to the ground, which would be a certainty if he had the temerity to leap in the direction of the rear of the train. This principle holds good throughout all nature. If two objects connected in motion in the same direction are not impeded in any shape, one communicates an impulse to the other in the direction of motion; but if they oppose each other, then, as a matter of course, the superior weight and velocity in the one direction will act as an impediment to the full force in the other.

discrepancy between the work performed by the one
stop and the work performed by the four stops; al-
though the grand jeu professes to accomplish as much,
it fails to do so. An attentive examination will show
the cause of failure to be that whilst the "grand
jeu" opens the four valves, it omits at the same time
closing the four little escapement valves. Thus it is
that the wind escapes so fast that the blowing be-
comes hard work to meet demands both of use and
waste. Why, then, are the escapements ineffective?
Because the large valves are not sufficiently de-
pressed to let the escapements fall and set close over
the apertures they should cover. So we arrive at the
cause of the defect-namely, that the poker or sticker
worked by the grand jeu is too short. Insert one
that shall be of suitable length, and it will perform
its work, giving results precisely the same as the
four stops for which it is intended to be a faithful
substitute or deputy.

In reply to question of "J. H." on same page.
Rivets for harmonium tongues are not of English
manufacture; would be obtained only by order from
abroad. They are needless, for a yard of iron wire
will answer for the purpose of amateurs' practice.
Manufacturers find it much cheaper to buy reeds
than to spend time on repairing them.
For tuning harmoniums ("Vibrator," page 69)
there is no royal road. It is tedious and laborious
work. The practised tuner, however, does not open
the instrument to each reed, he ascertains what half
a dozen or more reeds will require, bears in mind
which will want flattening, which sharpening, and
the degree of each, and with the catalogue on his
tablets of memory, he rectifies the lot, at once open-
ing the instrument, and by habit he can so work
with comparatively few discrepancies in results.
The finer touches are given in a final survey of the
whole.

"Feeders," concerning which "W. D.," page 21, makes inquiry, may be placed at bottom of case, that is to say, in horizontal position, that the feet may act directly upon them without intervention of levers for working. In some small instruments the plan is adopted, but it is not a desirable one for larger eizes, as the command over the wind is restricted and not easily managed. By leverage we can modify the extent of throw given to the feeder, and regulate the stroke to the pressure, considerations of importance when a large supply of wind is in requisition.

HERMANN SMITH.

and dejection of spirits, &c., which too frequently arise from the use of implements ill-constructed for their purpose. Communications in these pages of scientific and reliable information respecting sewing machines, from persons having no self-interest in the sale of them, may, while they advert to their comparative merits and defects, direct purchasers to the best system of construction, and so prevent poor people from being imposed upon by the delusive and exaggerated statements of unscrupulous vendors, who represent their own frequently worthless things as superior to all others. Thus, for many reasons it is desirable that the ENGLISH MECHANIC should take up this subject, and furnish in its pages practical and reliable information, which may be referred to as authoritative in the making and using of sewing machines.

This would seem to be a step in the right direction for technical education, and thus many being enabled to avail themselves of the aid and experience of intelligent practical and scientific men, may make successful efforts in improving sewing machines, which may greatly tend to their own and to the public advantage. If some of the workmen who evince decided talent in the construction of these machines could be encouraged to study and to excel in their business-if they would derive their pleasures from instructive books, instead of from demoralising drink-their own mental and physical powers would be improved, and I have no doubt that the sewing machines and other mechanical inplements which they would produce would manifest a corresponding improvement, and so may become more conducive to the pleasure and profit of all who use them. Working men may ask how it is that we cannot keep out foreign manufactured sewing machines We tak from America alone to the value of upwards of £200,000 annually, a sum that would employ 900 men at home in comfort, instead of roughing it in the colonies. We have a position, and the raw material at hand, the most convenient to make sewing machines for all the markets in the world, and ought to employ an additional 10,000 men. Our merchants would do their parts in selling. What is the reason we do not make? If it is simply excessive taxation, let it be discussed elsewhere; but if the misfortune be due to workshop mismanagement, it ought to be debated in these pages, to the ultimate benefit of employer and employed.

Fitting up the case of a single row harmonium, as required by "J. W.," page 21, in order to accommodate two rows of reeds, will be a very troublesome affair, and to carry out the design, securing at the same time the proper working of the mechanism, will be a trial to ingenuity. The size of case must be stated before a definite opinion can be pronounced, and another matter of consideration will be the size of bellows, which it appears are already made, for it will be useless to have two rows of reeds unless there is a provision for wind supply There are many sorts of sewing machines, to proequal to the amount required for their speech under duce stitching of various qualities-some for ornafull play. A sound board for two rows will measurement, some for strength, some for heavy, some for at least ten inches in width with utmost paring light goods. Some machines are very difficult to be down of frame; one made eleven or twelve inches learned and kept in order, although an experienced will give a better character, and more fullness of teacher may prevent much of the trouble from arising. power to the 16ft. tone. The two sets of reeds are In some there is little difficulty to learn without a said to be respectively of 8ft. and 16ft. tone, the teacher, a few lessons from printed instructions being latter being an octave deeper in pitch than the sufficient to enable a person to do common stitching former, and especially desirable for sacred music. in a few hours' practice. Some machines, the most difficult to be learned, amply repay the patience bestowed in acquiring a thorough knowlege of their working, and in the course of a few years confirm the truth of the adage, “A stitch in time saves nine," and that a good machine stitch will save ninety-nine. All the machines in common use make the one-thread stitch or the two-thread stitch. The former works thread from one side of the fabric, the latter from both sides. On the top side the stitching is nearly alike in all the machines. On the under side the onethread machine forms a loop, and in a few machines a half-twist is given to the loop. One class of machines P.S.-Pendulum. I notice a statement by "Cats-interlace the two threads on the lower side. All these eye Diamond," page 45, on the sympathetic vibration chain or loop-stitches will ravel out by pulling the of two pendulums; if the pendulums, however closely thread from one end, but the two-thread stitch is hung, are attached to different supports the same more elastic and durable than the single-thread stitch. manifestation will not arise. Professor Leslie has There are two classes of machines which make the shown that the vibration is conducted between the lock-stitch. One carries its thread from the reel in a points of attachment of the two pendulums, it passes shuttle through the loop of the needle or upper thread. along the fibre of the wood or metal rod, a pheno- The other has its thread wound in a spool, and a mena quite distinct from the sympathetic vibration rotating hook takes hold of the needle thread, and of strings excited by the mediuin of air. carries it around the spool. For strength and beauty, and command of stitch, the shuttle is the best system. The spool machine makes the least noise, and is very rapid, which advantages over the shuttle machine were at one time very great. The spool machine has undergone the least alteration, but the shuttle machine has been improved so much that it scarcely owns its parentage, except in the original movement of needle and shuttle. By reconstruction, the other parts, in some of the modern machines, nearly equal the spool machines in their quiet and speedy action. The quietness of the spool machine is very much due to the use of a curved needle worked by a rocking lever. and more liable to break than the straight needle. The curved needle is more expensive in the first cost, The nature of these sewing instruments (which will vary nothing in principle) having been described, it be subsequently found by a person studying them to will then be requisite to give patient and observant attention to the formation of the various stitches, and each distinct sort of stitch. to the action of the instruments in the execution of This being thoroughly done, the student will the more easily acquire the knowledge of a variety of constructions to be hereafter presented to him in these pages. A PRACTICAL MAN.

SEWING MACHINES.-I.

SIR-The history and development of the sewing
machine are subjects of great interest to the mechanic.
No other machine of recent years has stimulated the
inventive faculty and the application of mechanical
skill to a greater degree. It has employed a large
amount of capital and skilled labour with great and
deserved success, and it is likely to continue to engage
for some time longer.
the attention of inventors, capitalists, and machinists
The failures have been so fre-

quent and numerous, that they are well known to the
trade, which, indeed, often evinces gross and culpable
ignorance of mechanical principles.

If the earth does rotate at this fearful speed, what becomes of the centrifugal force which must be called into existence at the equator (and proportionally as we approach the poles)? This force is a universal principle in the circular motion of all bodies in proportion to the extent of the path traversed and to the speed exercised. This being the case, a tendency in all things to fly from the surface of the globe is manifest, and it is here where gravitative attraction steps in, as it were, and presumes to settle the difficulty by applying a power controlling this centrifugal force by a power 17 times as great as the centrifugal force existing. We shall see when we come to examine the theory of gravity, at what an erroneous conclusion its Some, who are unable to invent or improve, but supporters have arrived. The centrifugal force not deserving inventors and patentees, have offered for who are fraudulently desirous to take the trade from being called in question, except as its being controlled sale worthless imitations, which have occasioned as above, it need only to be further said that indepen great trouble and expense, not only to themselves, but dent of this gravity no living thing could exist, except-also to the users of their useless productions. ing, as I have before shown, near the poles. It is a remarkable ching that some people, who think it criJOHN BEARDSLEY. minal to steal a pound of brass, will not hesitate to take by fraud what is worth more thau a pound of gold-that which was produced by the hard and honest exercise of their neighbour's intellect. But as the terms of some of these patents have expired, examples of the several classes, with descriptions and drawings, will be given in these pages, so that even the amateur mechanic may be enabled to make a sewing machine, and find ample scope to exercise and display his mechanical skill.

(To be continued.)

HARMONIUM REEDS.-PENDULUMS. SIR,-To several questions on harmonium matters, I have the pleasure of giving replies, A few words will solve J. H. C.'s" difficulty (page 69), and will probably be useful to others, the defect he states being one of common occurrence. The instrument named hus two rows of vibrators, consequently it has four of its stops acting directly to give speech to the vibrators or reeds; these we call register-stops. Every instrument ought to have an ample supply of wind for its requirements under the play of the fullest harmonies. The first point to be decided before testing the grand jeu "is the adequacy of the windpower when all the register-stops are drawn. We will assume this to have been ascertained in the affirmative. The " grand jeu" stop acts by interior mechanism upon the same valves that are acted upon by the exterior apparatus of the several stop-rods and levers; the defect is not in the wind, therefore, it is in the mechanism actuating the valves; there must be some

The sewing machine presents an extensive field of inquiry to the student of mechanical appliances, exhibiting a greater variety of ways to effect a definite object than can be observed in engines, lathes, or other similar structures, which, it is well known, have had longer time and more experience to be brought to perfection. The readers of the ENGLISH MECHANIC Who have the advantage of contributing to its pages may sometimes employ their scientific acquirements in exposing popular errors, and showing the merits or defects of the various species of sewing machines, and thus in some measure contribute to the welfare and pleasure of a numerous and deserving class of their toiling brethren, by rendering their tasks more facile and agreeable, and preventing the irritation of temper

BIG HEADS, BIOLOGY, AND MATRIMONY. SIR,-There is a time in every man's life when he others do not seem to know it nor acknowledge it. acts foolishly; some do so, discover it, and improve, Of the latter there is little hope of improvement, and of these two classes the world appears to be made up. I have been a reader of the ENGLISH MECHANIC for some time, and have been so pleased with the gradual improvement it has made, that I have introduced it to my workpeople.

that one person has influence over another in mesmerWhen your correspondent "Dise" asked how it was ism and electro-biology, seeing that no one replied, I question, and which has not yet been refuted-but a gave what I believed to be the proper answer to his heap of abuse was cast upon me instead. Fifty sumlearner, and not ashamed to acknowledge it. Exmers have passed over my head, and I am yet a perience has taught me that the man who abuses you because you differ from him is not the man that society can look to for improvement. I name this, knowing

that others are prevented from contributing to your journal, believing from the spirit already shown that abuse might follow from those who know little of the subject they oppose. Three letters appeared the week after mine, in reply to it. That of "Suburban" is candid and respectful; those of "Saul Bymea" and "AntiHumbug." do them no credit.

In reply to "Saul Rymea," I beg to say a moment's reflection would have taught him the folly of his argument. If Lord Penzance was a practical phrenologist, it would have made no difference, as his duty is to administer the law, not to alter it. "Saul" further says that all clergymen should be practical phrenologists by Act of Parliament, thus inferring that an Act of Parliament can give a man brains, because, if all clergymen could be made so, a thing impossible, they could not prevent foolish and unequal marriages. A man may preach a good sermon, and yet not have the ability for a good phrenologist.

All progress is slow, whether to good or evil, and those unfortunate people who have to appear before Lord Penzance do not come suddenly to the unfortunate position they are brought to, but are led from bad to worse, from a look to an aet; and it is for "Saul Ryinea" to prove that the attracting and repelling influence referred to in my letter has had nothing to do with bringing them into this unenviable pusition, and causing them to seek associates more congenial to their feelings and passions.

I still believe, whatever may be said to the contrary, that if young people were to follow the advice of a practical phrenologist, much misery would be prevented and fewer would separate. Here we have a married couple; did they live in love and harmony previeus to their coming before Lord Penzance? If they did, why seek a separation? If they did not. let the cause be traced to its origin, and you will find that fifteen out of every twenty were never suited for each other. One thing is certain, where husband and wife live in love and harmony, there is little fear of their disgracing themselves with those crimes that bring people before Lord Penzance.

small brain. If we take size as a measure of power,
then we must submit that in each head the large
organs will have more power than the small ones; and
although two brains may be equal in size, one,
from possessing a finer texture, will have a more
powerful constitution than the other, always keeping
in mind the temperament, which, as "sigma" justly
remarked, is the key to the whole secret. The tem
peraments are distinguished, of course, by the coun-
tenance and general formation of the body. This will
give an index to the natural qualities, and will be a
guide to those who intend to study this interesting
science.

In most cases, a person with a large brain and small
muscle will naturally incline more to mental than
muscular labour, whilst a person with a small brain
and large muscle, if of a bilious or sanguine tem-
perament, will incline to exert himself more in bodily
labour. These remarks of course have reference to
healthy brains, as the brain, like the body, may be
diseased, and yet not lessened in size, but rendered
almost, if not altogether useless,

I make the foregoing remarks respecting large and
small brains that my words in a former letter may
not be misunderstood.
I now conclude, by advising
young men to read "Cobbett's Advice to Young Men,'
especially his "Letter to a Lover." His remarks,
though amusing, are interesting and really useful,
and will be found not far from the mark. My time
being taken up with business matters prevented this
appearing sooner, and as before stated, being written
amidst the noise of machinery, and at intervals, your
readers will have to take it for what it is worth.
T. D., Workington.

EXTRACTS FROM CORRESPONDENCE.

MR. BIGGS ON ALGEBRA.-"Hugo" writes:Mr. Biggs asks me, on page 35, why he used the radical sign? Thave not the faintest idea why he did so; he might just as easily have inserted the actual square root of 175, at least up to a few places of decimals. He has not taken the square root of the expression in question, for that is impossible but he has certainly attempted it. I must still, therefore, beg him to inform the readers of the ENGLISH MECHANIC how he finds that

175

4

175

2

I will not occupy any more of your truly valuable
space further than to express a hope that such state-
ments as this will not find a place in Mr. Biggs' notes
on algebra."

MACHINERY VERSUS STEAM.-"A Clerical
Subscriber "writes:-"Many small engines are now
made to work by clockwork. Why are they not made
on a larger scale? What is done on a small scale
may be done on a large one. The beautiful adjustment
of a modern watch may be introduced into a loco-
motive; greater safety would be obtained, enormous
expense saved, and coals delivered to the poor at
58. a ton; besides, in the case of steamers, they would
always be independent of fuel by the change. It may
seem improbable, but we must remember the derision
with which steam was ushered into existence as loco-
motive power."

an author,' &c. I see with pleasure that a F.R.G.S.' intends to send some accounts of the proceedings of his society. This would be much approved of by many readers, and add to the popularity of the paper. A suggestion was also inade last year-I repeat it now-the number of re ders being much increased it might find more echo; it is that when a new produce comes somewhere on the market, one or other reader might mention it in the paper. He will be sure always to give or to receive information."

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[1836.]-ASPHALTE VARNISH.-This can be made by boiling common coal tar until it shows a disposition to harden on cooling; this can be ascertained by rubbing a little on a piece of metal. Then add about 20 per cent. of lump asphalte, stirring the same with the boiling coal tar while melting therein, until all the lumps are melted, when it can be allowed to cool and kept for use. This makes a very bright varnish for sheet metals, and very cheap and durable. Common coat tar will not dry readily, as it is not properly boiled to expel the volatile hydrocarbous, which prevent its drying. It should be boiled out of doors, as it might take fire and burn the building.-AMERICAN SUB

SCRIBER.

(1970.]-VARNISH FOR IRON PATTERNS.-A good varnish for iron is made as follows:-Take oil of turpentine and drop into it, drop by drop, strong commercial oil of vitriol; the acid will cause a dark syrupy precipitate in the oil of turpentine; keep adding drops of vitriol until the precipitate ceases taking place, then pour out the liquid and wash the syrupy mass with water, and it is ready for use. Heat the iron to be varnished to a gentle heat, and apply the syrupy product and allow it to dry; it will be found, on being dried, that this varnish has become incorporated with the surface of the iron, and therefore very permanent and durable.-AMERICAN SUBSCRIBER.

[2167] LATIN. Get Dr. Smith's "Principia Latina," Part I; Murray, price 38. 6d. Carefully learn each vocabulary a day or two before writing out the corresponding exercise. Learn the declensions and conjugations thoroughly. Make a practice of daily declining or conjugating one or more words, and by continued application" Reader" will soon be able to get a fair knowledge of the language.-C. H. W. B.

"Anti Humbug" knows a woman who has a drunken husband, who beats her, and because he does so, he thinks my arguments do not stand good. Pray, what has this to do with the subject? I was not writing about fools and madmen-I can look upon drunkards as no better. I have heard it said that two-thirds of the men who turn drunkards after they are married are made so on account of the unsuitableness of husband and wife. I will not hazard this assertion, although I believe there are many. That the human body contains an attracting and repelling power I have no doubt, call it by what name you like; I call it negative und positive, and in this I am borne out by one of the first authorities of the day, Dr. J. B. Dods, who first discovered electro-biology, or as he calls it, "Electrical Psychology, or the Science of the Soul." The Doctor was twice invited to deliver those lectures before the American Senate. Many years before I knew anything of phrenology or mesmerism, I proved to my own satisfaction that the human body contained au attracting and repelling power, and was astonished when reading the above author to find that he not only bears me out in this, but clearly proves in his lectures that the body does contain negative and positive poles. The work may be had of Tweedie, Straud, London. I give a short extract in the Dr.'s words. In speaking of the Fowlers of New York and George Combe, he says, on page 41:-"They have made a righteous developement of true character in the phrenological examination of thousands of human heads; have directed the anxious parent how to train up the child of his affections; have pointed out to the sighing lover how to choose a congenial spirit of companionship for life; and have poured the light of mental and moral improvement in silvery streams on the graud Empire of Mind, yet such a science as this has been called a humbug." Again, on page 54, the Dr. continues:-" It will be readily perceived by everyone acquainted with electrical science, that if I can find positions may be observed, not only from one day to Versity is a Cantonal, and the school a Federal instituan individual standing in a negative relationship to myself, or by any process render him so, then I, being the positive power, can, by producing electrical impressions from my own mind upon his, control his muscles with the most perfect ease. This is evident, because the positive and negative forces electrically and magnetically blend, are equal in power, and paralyse each other; or, on the contrary, produce motion." Again, on page 190, he refers to the negative and positive forces in man, which is too long to copy here.

Some of your readers may not be aware that it is easy,
SPOTS ON THE SUN.-"G. C. C." writes:-
with any good opera-glass, to see distinctly (though
not, of course, for purposes of scientific observation) the
spots on the sun's surface, bysimply taking out the upper
or lower pair of lenses, and blackening their interior
now visible, and a great change in their relative
surface over the flame of a candle. Several spots are

another, but if looked at at different hours on the
same day."

to

[2180]-ENGINEERING IN GERMANY.-For the benefit of "Y. P. W.," and others, allow me to make an extract from an article by H. E. Roscoe, in Nature. science schools, I may cite the two celebrated schools He says:" As a type of this interesting class of of Carlsruhe and Zurich, beginning with the Carlsruhe school with its 600 students. gramme, the school was declared to consist of one In the original progeneral and seven special departments. The general department, called the Mathematical, furnished instruction in mathematics, in natural science, and in follows:-Duration of complete course-1. Mathemodern languages and literature." This programme has been slightly altered, and now the schools are as matics, 2 years. 2. Civil Engineering, 24 years. 3. Mechanical Engineering, 2 years. 4. Architecture, 4 years. 5. Chemistry, -. 6. Forestry, 3 years. 7, Agriculture, 23 years. In Zurich exist both a University and a Polytechnic School, and although the unition, they are so far allied that they share one magnificent building, and many students of the university are, at the same time, pupils in the school. The most important department of the Polytechnic School is that of mathematics and engineering. the lectures in the Engineering Department of the The following extracts from the prospectus of Zurich school show how much more complete is the scheme of instruction there than has at present been found possible in England. B. Department of Civil Differential and integral caleulus, descriptive geoEngineering (duration of course 3 years). 1st year-metry, principles of construction, practice in construction, drawing, experimental physics, experimental chemistry. 2nd year-Differential equations, technical mechanics, geometry of three dimensions, perspective, technical geology, topography, drawing, descriptive mechanical construction, surveying. 3rd year-Theoretical mechanical construction, astronomy, geodesy,

ments.

THE ILLUMINATED PORTION OF MOON.-Mr. John Beardsley says:-"I had overTHE looked the letter of R. L. J.,' in No. 261, until a friend called my attention to it, and although R. L. J. says my diagram helps to prove "Sigma's" views instead of my own,' he fails to show how it does so. My argument is that if he extends his thread not 33ft. I have for some few years back paid attention to only, but if he could for 33,000,000ft., he would never medical galvanism, and often found, when applying find that the plane of such distance would be truly the battery to different parts of the body, that the parallel to the higher object, simply because, as I said influence which I intended to produce was counter-before, the further he moves from the object the less acted, and when the poles were reversed, the influence will be the angle formed by moving a given distance, was also reversed, thus clearly proving that the body, until such angles would not even be discernible. as well as the battery, contains its negative and positive poles. Another proof that will bear me out, DIGITALIN. -" Pharmaceutical Student" writes:and which I think equally as strong as the last it is "Many thanks to the gentlemen who have replied admitted by scientific men that the atmosphere is Godfrey for pointing out my error: and I thank construction of iron bridges, railways and iron roofs, my query respecting digitalin. I thank Mr. charged with positive electricity, and the earth, as well as the food we consume coming from the earth, E. K." for his kind suggestion. I vaporised every-drawing. In addition to these courses, there are is charged with negative electricity. If you sit in thing that was volatile at 2120 in vacuo, air pump similarly extensive programmes for the other departa current of air, with your back to it, you are almost constantly going, until not another bubble would rise. The expenses are small. At Zurich, any of certain to catch a cold, but if you turn your face to it, No heat was applied afterwards except what it received the regular courses of the distinct departments or there is not so much danger. Again, when out in from the warm acid acetic solution. Amongst our schools, can be attended for the payment of 109 francs, a cold day, we instinctively cover the back part of the readers who take an interest in pharmacy, and who or about £4 43. for the session of nine months.-C. H. neck, and leave the front part bare, there being an have attempted the extraction of the less stable ba-es W. B. attracting force between the back part of the neck and (the isolation of which I believe to be extremely the atmosphere; we feel the cold more keenly in the difficult), will they favour me with their result, as I at neck, whilst the face throws it off, as if containing a present have but operated on the more stable? I had repulsive power. Surely with these proofs so clearly been successful till I was brought to a halt by digibefore us it is too much for any man to say I am talis. In theory I have a universal process for the talking nonsense; if so, the author above referred to extraction of alkaloids. I should be pleased to submit has written a book full of nonsense, but it is such as it to the notice of brother students. Is there any will stand investigation. Your correspondents try to work devoted to the extraction of the vegetable make it appear as if I was led away by big heads, or large beads. If they will kindly refer to my letter, they will find no reference whatever to large heads. I mentioned large brains as taking the lead; I should have qualified it, but when I tell you that my letter was written amidst the noise of machinery, it will, in a measure, account for a slight error, which otherwise would not have occurred. The words, four kingdoms, should be kingdom,

That I may not be misunderstood, permit me to say that I endorse "Sigma's" description of large and

bases ?"

SUGGESTIONS. &c.-"Henry H., Namur, Belgium," says:-"I am happy to see the continued success of our ENGLISH MECHANIC, and must tell you of the several satisfactory letters I have received from my friends to whom I had recommended it. I had the pleasure to procure a good number of subscribers, also some new contributors; all see with the greatest satisfaction the continued improvement of your publication. Recipes should be followed by the words tried,' or 'proved,' or 'extracted from such

[2209.]-OVERLAND ROUTE.-If two letters are posted to India, the one via Southampton would proceed from that port by a ship which would enter the Mediterranean by the Straits of Gibraltar, and land her mails at Alexandria. The other letter, via Marseilles, might be posted in London six days later, and would go by Dover to Calais by packet, then by rail to Marseilles, and thence by ship to Alexandria, and so join the other letter. The extra threepence is well earned by the delay of six days and the extra trouble. -F.R.C.S.

[2232]-SOLUTION OF PROBLEM.-On p. 44, No. 262, for hypothenuse is divided at "8,'' read at " D."— BERNARDIN.

[2234]-COLOURED OBJECT GLASS. - I can second what your correspondent says respecting the excellence of Solomon's telescope. The red glass seut with it is not sufficiently dark; in fact, I find it impossible to use red glasses, as they are so burning hot

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240 cubic ft. per minute will, by it, give 12 to 14 h.p. Pressure no object.-J. C. SHEWAN.

[2327.)-READY RECKONER.-The best one published is by W. and R. Chambers, called "Commercial Tables," in which he will find everything he requires.

[2328.]-DEFECTIVE GUTTER-If "Salop" were to brush over his cast-iron gutter inside (when perfectly dry, and with the rust scraped off) with hot boiled gas tar or hot pitch, I think that the "weeping" through the metal would be effectually stopped. Q. Q. R.

transmitting all the heat rays. He will find a great im- [2298.)-REMOVING OIL PAINT FROM SILK.
provement if he gets their revolving sun glass, with 4-If "Cantab" will make a strong solution of com-
different colours. Of these, the London smoke," mon soda and hot water, apply hot with a brush
No. 3, will enable him to look at the suu for hours several times over, then rinse well with cold water,
without the trouble of a second glass. But the he will find it answer his purpose.-W. W.
grandest views I have had of it have been with the
[2299.]-GENERATION OF ELECTRICITY-If-W. STEPHENSON.
2 day eyepieces; these give the best idea of its size, "Lancashire Lad" will take a piece of iron tub hoop,
and while showing the penumbra and faculæ, &c., give a
magnificent bird's-eye view of the whole mass. For about 4in. long, bend it in the form of a clamp
these I have had a dark glass of "London Smoke
made by cutting out the brass of the ordinary and force one part between the iron framework and
day evehole, leaving only a narrow rim just sufficient woodwork at the end of the carriage, the other part to
to hold the glass, so that the end of the tube is all rest on the brasses, or, what we call, tops, you can
glass. This answers admirably. Free by post 7N. screw it fast to the spindle box, one end to touch the
The revolving sun-glass, also adapted for Venus and brass, the other to touch the iron work. It has never
the full moon, is 10s. 6d.; both valuable additions to the been found to fail where properly applied. The cause of
telescope; the last will screw on the astro-eyepieces electricity is the high temper of the spindles and speed
only. With this telescope I can discern easily the 3-SELF-ACTING MINDER, Blackburn.
doubles of Orion's belt-a severe test -AMATEUR.
[2270.]-MOTION OF WATER.-J. Crompton does
not state enough in his query to be able to give a very
definite answer. If the hole is through a thin plate in
the side of a cistern or pipe, 5800 gallons per hour
would pass through it, or about 929 cubic feet.-
Q. Q R.

[2270]-MOTION OF WATER.-J. Crompton must particularise, in order to get a correct answer. Is the orifice in the form of the rena contracta, and what thickness is the plate in which the hole is bored; this latter will affect the vena contracta, and consequently the quantity of water discharged. If J. Crompton has 381b. pressure per square inch, his head of water is equal to about 85 5ft., which would be valuable for many purposes, even with a quantity of water sufficient to supply only a pipe lin. in diameter.-SENEX.

[2273]-TELESCOPE. Dr. Kitchener's telescope. known by the name of the "Aubert," was advertised for sale in the Athenæum of Feb 9, 1861, price £130, by the Rev. A. F. Padiey, Lincoln. This is the "Beauclerc Object Glass," mentioned by "G." What became of the Doctor's other telescopes I do not know G. J. W.

12275.]-SUN GLASS FOR TELESCOPE.-J. H. Ward will find the best glass for viewing the sun to be the neutral tint wedge, made for that purpose, and sold by the opticians. Or he can try such combination of common coloured glasses as will give the nearest approach to neutral tint, avoiding deep red, which seems to blot out detail. I find purple, green, and blue, cemented together with old hard Canada balsam (melted, and the glasses made hot), avoiding air bubbles, to answer very well, allowing the mottling of the surface to be well seen. Strips, 2in. by lin., with an extra thickness over half, in case the other should not be sufficient to prevent the light being unpleasant, or combinations with different shades of the same colours, might be desirable.-S. B.

[2275.1-SUN GLASS FOR TELESCOPE.-Any coloured glass, sufficiently dark and clear, may be used to view the sun, or even a piece of smoked glass. More costly eye-pieces for this purpose are made by optician. If no other protection than coloured glass is used, the observer should contract the object-glass to 2in., or he may injure himself very seriously. Throwing the image of the sun on a sheet of white paper, held at a proper distance before the eye-piece, is not a bad plan.

-G. J. W.

[2304.]-PALO DE VELA.-The Spanish word "Palo," means a wooden staff, a mast, and when joined to another word, tree or wood; Palo de tinte, dyewood; Palo de Vela,' candle tree or candlewood; but this candlewood is not the same as the candlewood of Guiana and the Antilles; this latter is so called because it is used by fishermen during the night. The "Palo de Vela" receives that name from its fruit, which is 3ft. long, and candle shaped; a note on that fruit has just been published, p. 45, No. 262, of our ENGLISH MECHANIC, extracted, I believe, from the French review Les Mondes. Botanical name is Parmentiera pendulus; the genus Parmentiera is an undetermined genus of Gesneriacea, near the genera Crescentia and Bellonia. The caudlewood from the Anlilles, &c., comes from Amyris sp. (Toxifera?) Burseracea The name of candlewood is also given in Guiana to the wood of Toulicea Guyanensis, Aubl. of the soap-order or Sapindacea; perhaps it is also used for lighting purposes.-BERNARDIN.

[2306.]-MORE STEAM WANTED-I think the boiler of "D. C. W." large enough for the size of his cylinder, and if he would only be at the trouble to turu the exhaust steam into the chimney, he would find it act as a good steam jet, and would cause a greater draught on the fire, consequently making more steam. -F. W. W.

[2306.]-MORE STEAM WANTED. If "D. C. W." puts (as he suggests) four or five tubes round the smoke flue, he will probably get steam enough, but there is danger of superheating the steam so much as to make it act injuriously on the cylinder, packing, &c., so that I think the best plan would be to put in a few "Field " tubes from the roof of the fire-box. They are very effective, have good circulation, and I believe that all information about them can be obtained from Mr. Lewis Olrick, 27, Leadenhall-street, London.Q. Q. R.

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[2311.]-NEW WORM IN VICE BOX.-" A. E. " B." should bore the old worm out of his vice box, and at the open end insert a cast steel bush, cut with a good thread to fit his screw, and fasten it with a pair of small but strong screws, let in countersunk holes; by doing so, he will, with care and oil, find it better aud easier than a new box and screw. -TANGENT.

[2330.]-BOOMERANG.-The boomerang is a wonderful weapon, but it takes years to bring a man into the knack of proper use, "Et le jeu ne vaut pas la chandelle."—G. E. CRICK.

[2335.]-CONTACT BREAKER.-E. Tucker should make (if a good amateur) or buy one of Rhumkorff's double quicksilver contact breakers, as the only expense connected therewith is the evaporation of it small trifle of spirits of wine. He will not only find a increase the power of his coil, but find it a deal more manageable than the old spring and platinum point breakers. If he requires it, I will send a small drawing and description of it, as it is an instrument that has only come up just lately, and I have not heard of any in England. A col that gave formerly only a spark 9 centimetres long, was increased nearly 60 per cent. with a quicksilver instrument.-TANGENT. [2336.]-BRONCHITIS.-" A Three Years' Sufferer" will only get rid of his affliction by change of air. As to its degenerating into consumption, there is no fear of that, if there are no other concomitant circumnstances, such as hereditary or other predisposition, &c. I cannot refrain from expressing an opinion that it is highly undesirable to open the columus of the ENGLISH MECHANIC to questions of prescribing, as it offers the opportunity to the unioformed to perpetrate an infinite deal of mischief by the recommendation of their nostrums. A remedy which is useful in one case, may be hurtful in an apparently similar one.-F.R.C.S.

[2337]-STEAM INDICATOR.-The work recommended by the Science and Art Department, in their examination, is by Main and Brown; Longman publisher.-W. STEPHENSON.

[2346.]-GEOLOGY.-The works edited by Austed, Jukes, and Haughton, are all good, and are used at the examination as text books.-W. STEPHENSON.

[2346.]-GEOLOGY.-" Permian" will find these two books the very best, "Introductory Text Book of Geology," illustrated, 7th edition, 28.; "Advanced Text Book," 4th edition, 7s. 6d. Both works by David Page, LL.D., &c. Win. Blackwood and Sons, Edinburgh and London. There is also a "Handbook of Geological Terms," 7s. 6d., same author and pub. lishers.-BUSY BEE.

[2350] RAISING WATER. The cheapest, and even best, way, is by the simple suction pump, with not less than three clack-valves in the suction pipe. Any plumber will put such a one in for you.-SEÑEX. [2360.]-ALUM.-The shale is slowly roasted in large he aps, so as to oxidise the pyrites or sulphide of iron it contains, and generate sulphuric acid, which unites The shale is then placed in large pans, sunk usually in with the potash in the shale, and also with the alumiua. the earth, and lined with lead and fitted with steam

[2282.]-POWER OF STEAM.-The 32ft. length of steam pipe will not cause much loss of pressure if the home, make a lute of clay and ashes, and cover the pipes; here it is boiled with sulphuric acid, till as pipe is well covered and protected from condensation. providing that the pipe is not of a very small diameter, as then the friction would be sufficient of itself to reduce the pressure materially.—Q. Q. R.

[2283.]-PAINTING SCENES.-The best way to paint theatrical scenes is, 1st, to sew the calico together, 2nd, melt some glue so that it will be as liquid as possible, then mix the common paint used with oil, with it paint the scene and leave it to dry for about one hour. It won't crack, and no varnish need be used.-H. GARLAND.

[2290.]-BROAD PENCILS.-Winsor and Newton sell the pencils with broad oblong leads.-G. E. CRICK. [2291]-THEOREM.-In answer to "E. W. V.," I

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[2296.]-COPPER DIE.-Take a piece of clean copper, and having heated it to a blood red, place it in a strong iron ring on the anvil, and hold the die over it whilst an assistant strikes a blow with a sledge hammer. The copper will be found to be an exact counter

[2311-NEW WORM FOR VICE BOX-To braze the screw in a vice box, or any inside work. Having twisted your inside thread round the screw, file and fit till it reaches the bottom of the screw box, taking care not to drive it in too hard, and make two marks, to enter it always the same way. Having driven it box with it (the screw part), but not much more than one-cighth thick - the reason of this is to prevent the brass running too soon, and also to protect the boxthen turn out your screw and put in some powdered borax, shaking it well about, then put in about 1 oz., or 14 oz., of brass binding wire in a flat bank, reaching from top to bottom of the box, take it in the tongs by the closed end and secure with a coupler, and having a good fire ready, put in the box, and gently turn it round for the clay lute to harden, occasionally taking it out, then let an assistant urge the fire till the box becomes of a bright cherry red, and turn it round constantly. When the wire runs, a blae fire will come from the mouth of the box; when you see this, uncouple the box and roll it round on the floor, to distribute the braze, till it goes down to a low red. Having prepared your strip for the inside screw, just enter it in the thread of the male screw and pinch both in the vice, tapping it down into its place with the hammer, and turning the screw round occasionally to nip it in a fresh place, till it is all gathered, then proceed as above.-G. E. CRICK.

[2316.]-THE SLIDE VALVE-The writer finds
all necessary information in the "Treatise on Steam,
&c.," by Main and Brown, price 12s. 6d., used by the
certificated teachers under Government, a capital
work.-W. STEPHENSON.

[2321.]-SWAN PROCESS. -I believe that the
"Autotype" Printing Company, 36, Rathbone-place,
Oxford-street, London, (who possess the patent right
of that process), have just issued a manual of autotype
printing, from which "Scribo" will probably be able
to obtain the information he requires.-Q. Q. R.
[2823.]-WATER POWER.-1. Multiply the quantity
of water per minute in lbs., by the height of fall in
feet, and divide by 33000, the "nominal ".p. The per
centage of useful effect will, of course, differ accord-

liquor, at the proper state of concentration, is then much as possible of the alumina is dissolved. The drawn off and mixed with sulphate of potash, which is usually obtained direct by acting on chloride of potassium. Alum is generated, and being far less soluble than the salts it is derived from, precipitates in fine grains, the liquid being well stirred during the cooling. 1 These small crystals are then washed with cold water, and then dissolved at a boiling heat, and run off into vats to crystallise. A very large proportion of alum is made with sulphate of ammonia instead of potash, which is obtained from gas liquor. Ainmonia alum is £2 a ton less value than potash alum, but is seldom so free from iron, and is useless for several of the purposes for which alum is employed, such as the preparation of paper hangings, especially the white

satin papers-SIGMA.

[2360.)-ALUM-The old way of extracting alum from shale, was the following:-The shale was first exposed to the air, when the oxygen of the air, assisted by moisture, effected a wou erful change in it. The original hard stony substance became split up into thin leaves, and became studded over with crystals. When the alum shale thas weathered was digested in water, sulphate of alumina and sulphate of iron were dissolved out; this solution was then treated with chloride of potassium, which decomposed the sulphate of iron, forming sulphate of potash and chloride of iron. When this liquid was evaporated to concentration, and allowed to cool, crystals of alum became separated. The crystals thus obtained were not, however, free from iron, and therefore required to be re-dissolved in water, re-concentrated, and recrystallised. The same operation had to be repeated a third time before the alum was pure. As the weathering of the shale took some years to proceed, a more expeditious method had therefore to be resorted 10. The shale is now broken up into fragments and

part of the die, if this has been carefully and quickly ing as the wheel is more or less perfect. For example:-piled up over brushwood in long ridges, and the brush

done.-CHIP.

[2296.]-MONOGRAM DIE.-" Cantab" will find it the best plan to electrotype his copper counterpart on his steel die By-the-bye, this counterpart has strangely received the misnomer of a "matrix." which term obviously belongs, of right, to the sunk die.-F. R.C.S. [2296.]-MONAGRAM DIE.-The copper matrix is not cut, it is stamped or cast.-IOTA.

[2297.]-VIOLET INK-I forward two recipes for "Cantab's" benefit-1. Boil Soz. of logwood in 3 pints of rain or distilled water to 1 pint; strain, and add 14oz. of clean gum (Arabic), and 2 oz. of alum, in fine powders; agitate frequently until dissolved. 2. Cudbear 1oz., pea lash 1oz., mucilage (gum Arabic), 2oz, soft water to make a pint; pour the water hot on the cudbear and pearlash, allow the mixture to stand for 12 hours, then strain and add the mucilage; 10 of rectified spirit may also be added.-EDWARDUM A.

13

Breast wheel, 60 per cent.
Useful effect Overshot 65 to 70.
Turbine 75 to 80 (with so small a
quantity of water and so small head, I cannot recom-
mend turbine in "G. P.'s" case).

N.B. AS "G. P.'s" is a very elementary one, per-
haps it will be necessary to inform him that one c. ft.
of fresh water, weighs 624lb., hence, in his case,
621bs. 4 × 203 c. ft. x 7ft.
=264 horse power.

33000lb.

2. The volume of water behind the dam, will have no effect so long as the quantity escaping upon the wheel and the height of fail is the same. - SENEX.

[2323.] TURBINE.-If " G. P." can have a dam 7ft. high, he can work my turbine to great advantage, by having the spout fixed in the top part of the dam;

wood being set fire to, the coaly matter of the shale begins to burn, and the whole ridge undergoes the process of roasting; the results of which are the same as the weathering operation. This material is afterwards worked up as above described.-MINNEHAHA.

[2370.]-UNSOLVED PROBLEMS.-No saving of power would result from the use of J. Bannell's invention, however smoothly it may work, since no power is lost through the present mode of obtaining rotatory motion from the reciprocating piston. Many elaborate and ingenious mechanisms have been devised to obviate the use of the crank, from the most erroneous notion that the crank causes a loss of power. But it will be a very difficult mat er to find any more simple or efficient contrivance for the purpose thau the crank, aud I would advise J. Bannell to spend neither time nor money in further developing his invention.-W. H. N.

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