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these results (forming part of a series which I obtained Ly long and laborious calculations) were not obtained by Mr. Lockyer himself-not even inverted commas. But I repeat, as respects this passage and three other far more noteworthy instances, I make no charge against Mr. Lockyer, save of having forgotten to duly indicate the source whence he had derived his inforruation. Had the complete omission of my name from his book been intentional, the matter would have been lifferent. As it is, I should not have referred to it at all but for the angry and discourteous note he appended to a paragraph in which I had paid him a high but not undeserved compliment.

The fact is, that Professor Pritchard and Mr. Lockyer combined their forces to attack me (apparently for no other reason than that, like them, I work in the field of popular astronomical literature). If in self-defence I have faced them, and dealt each a blow" straight from the shoulder," they have themselves only to thank. I am neither quarrelsome nor thin-skinned; but no one shall make unjust and ill-mannered attacks upon me with impunity. Pacem amo, bellum non timeo. RICHD. A. PROCTOR.

WINDMILLS.

averted, if the "agriculturists of England" had exercised their common sense. It is pitiable to find that they do not give a wider meaning to their own proverb of "making hay whilst the sun shines;" if they did so, they would "catch water when it rained," and preserve it in tanks properly protected, which would be sufficient to supply all their wants during the drought. In conclusion, allow me to ask "R. P." upon what authority does he assert that "clouds passing over us, unless drawn down by gunpowder, empty themselves into the German Ocean?" I feel inclined to think this is an original idea, and that your correspondent is

his own author.

LEX.

[205] SIR,-During four years whilst I was at Woolwich, when the sky was very cloudy and overcast, whenever the artillery fired upon the Common rain generally ensued. I am inclined to think that a rapid succession of discharges from field guns would prove more efficacious than a few discharges at intervals from heavy guns.

OLIVER HALDANE STOKES, Captain (late) R.E.

SHOULD BE TAKEN.

this may in part explain its value; but how it acts is still undetermined.

Some people find the oil unpalatable, from the manner in which they take it. Thus, some take it upon ale or porter, others upon milk or water. Can it be wondered at that such patients cannot "master" the oil? I have always found that the oil can be taken better upon some orange wine, or some mixture conThe acid covers taining quinine and sulphuric acid. the taste of the oil, and the quinine acts also as a tonic. Some patients cannot even take the oil when thus mixed with the acid mixture, and for the use of such I recommend the following:-Take of picked gum Tragacanth 4oz., dissolve in 20oz. of boiling water, add sugar according to taste, now pour into this mucilage 10oz. of the best cod-liver oil, shake well; three drops of ess. lemons, and the same quantity of ess. almonds should now be added, and if you wish to keep the mixture for some time add 2oz. of brandy. In this compound the oil combines with the gum and forms an emulsion of a milky-white colour, which few will know from a well-made custard. The dose of this mixture is just double the quantity of the pure oil. The dose of the pure oil is from 1fl. drachm to loz., taken at the time of a meal or immediately after food. It is often advantageously administered able to take his at dinner-time, and so dispense with a pudding.

[203] SIR,-In reply to "Derf Errac," page 450, HOW COD-LIVER OIL IS MADE, AND HOW IT at bed time; and my friend, "A Mechanic," will be letter 152, I should recommend him, before going to work upon models, to procure Smeaton's work on the "Theory and Construction of both Vertical and Horizontal Windmills." Smeaton was the engineer who built the famous lighthouse on the Eddystone rock, near Plymouth.

He should also know that the rustic form of horizontal mill was in use among the Tartar nations before the time of the Crusades. Vallani's plan for the same ob. ject may be frequently seen set up in the gardens of retired sailors, in the form of four full-rigged ships fixed at the extremities of four arms revolving upon a central pivot, a form that has been known ever since vessels at sea were found able to turn a complete circle with the same wind. All these forms are powerless for effectual work, unless constructed of colossal dimensions, and then their speed is so slow that formidable trains of wheels and pinions are required in order to perform any useful work

"Derf Errac" is astounded at the magnitude of the proportions of my horizontal mill, but the arms are only 18ft., whereas in the common vertical they are often 30ft. long. It is true that there is an addition of 12ft. to the radius, for the funnel openings are indispensable for concentration of the wind, without which no useful purpose can be obtained; and it may be observed that there being no movable parts, there

is no wear and tear.

If Derf Errac" would take the trouble to construct

a model of my machine at the expense of a few sticks and some sheet zinc, he will find the immense advantage of concentration still greater on the large scale. A horizontal windmill was to be seen at the beginning of the present century at the south end of Battersea Bridge, but being constructed on erroneous notions, it was soon done away with. It was in the form of a tower 80ft. high., with no provision for concentration, as may be seen in old views of Battersea Bridge. I was in that mill, however, before it was taken down, and found that it was only driving one pair of stones at a very feeble speed. HENRY W. REVELEY.

ARTILLERY DISCHARGES AND RAIN. [204] SIR,-I am not at all surprised that the Editor of the Times thought the letter of "R. P." (page 448) not worth publishing, for had your correspondent been as well informed upon the subject he writes upon as he professes to be, he would have known that the question has often been mooted, but no "right men" have ever thought it worth taking it up. By the way, what does "R. P." mean by "right men"? Does he mean Government officials, who might be induced by some "moonshiny" theory, to squander the public money in vague experiments ? or does he mean private individuals ? If the former, taxpayers would raise a very decided and rational objection. If the latter, I do not think any private individual could be found foolish enough to spend either time or money, for the benefit of a few, in making experiments, the theory of which is pure fiction.

I maintain that rain is not the inevitable result of a concussion of the air, for I have particularly observed the weather after artillery practice on more than one occasion, and as an instance of great concussion of the air which did not result in a fall of rain, I may mention the explosion of the Lotty Sleigh, in the Mersey, a few years ago. This explosion was so territic that the noise was actually heard at Birmingham, a distance of about 60 miles. But, supposing for the sake of argument, that "R. P.'s" theory be correct, I would ask him of what utility would a continuous discharge of artillery, or a gunpowder explosion, be under a cloudless sky? In cloudy weather it would be mere labour in vain, or waste of labour, to cause a concussion of the air for the purpose of forcing rain, inasmuch as a voluntary shower is, in nine cases out of ten, inevitable. Again, allow me to ask "R. P." how many explosions of "Government powder-mills" or continuous discharges of artillery" would be necessary to cause one shower of rain over the whole British area? I am quite at sea as to the relevancy "a stone thrown into a poud" has to an explosion of gunpowder, but perhaps there is some deep philosophy in the allusion beyond my poor comprehension. I think the "mythical millions" that a want of rain has already cost might have been saved, and the "calamity" of a continued drought not only mitigated, but completely

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[206] SIR,-As one of our subscribers has asked some questions about this important oil, I propose, with your permission, to lay before our readers a short account of the oil, and the best manner to administer

it.

As its name denotes, cod-liver oil is made from the liver of the common cod-fish, and other species of Gadus frequenting the seas of Northern Europe and America. The following are the most important species of the oil-yielding fish, in a medical point of view:Gadus morrhua or the common cod-fish; Gadus callarias or the dorse; Gadus molra, or the ling; Gadus carbonarius, or the coal-fish; and the Gadus mulangus, or the whiting. From this list it will be seen that cod-liver oil is the product of many other species of fish besides the com

mon cod.

The oil may be extracted from the livers by three different methods:-By exposing them to the sun to undergo a process of fermentation; by boiling them in water for some time; or by dividing the livers and permitting the oil slowly to drain from them. This method is now employed in the preparation of the best English cod liver oil. The following is the way in which the oil is made at Messrs. Bell & Co.'s establishment:The livers are collected daily, so that no trace of decomposition may have occurred, carefully examined, in order to remove all traces of blood and impurity, and to separate any inferior livers; they are then sliced and exposed to a temperature not exceeding 180° Fahr. till all the oil has drained from them. This is filtered; afterorder to congeal much of the solid fat (margarine), and wards exposed to a temperature of about 50 Fahr., in again filtered and put into bottles well secured from the action of the air.

Three varieties of cod-liver oil occur in commerce, distinguished by their colour-the pale, prepared in England, or elsewhere; besides which are the light brown and dark oil from Norway. The difference in colour in the different oils depends upon the circumstances attending their preparation-as the amount of heat employed, the state of freshness or putridity of the livers, the quantity of decomposed matter present in the oil, and the length of exposure to the atmosphere. The following test is given in Dr. Garrod's "Materia Medica," from which also I have obtained some of the facts as to the preparation, &c., of the oil. When pure cod-liver oil, spread in a thin layer on a plate, has a drop of oil of vitriol added to it, a beautiful lake or crimson colour is produced, rising from the point of contact of the oil and acid, and rapidly spread ing over the surface. This is probably due to the action of the acid on the biliary principles present in the oil. By this simple test the pure oil is at once detected; for when other oils not of hepatic origin are present, the sulphuric acid does not give the lake colour, or this becomes immediately mixed with and obscured by a dark brown substance from the charring of the oil. Such is the case with whale or seal oil, also with olive and other vegetable oils. Some of my readers may wish to know what cod-liver oil is composed of. It contains oleine, margarine, various biliary principles, also phosphoric and sulphuric acid, with salts of lime, magnesia, and iron, and a peculiar substance called gaduin-very insoluble in ordinary menstrua, but soluble in sulphuric acid, and giving a blood red colour to the solution; also traces of iodine and bromine; the proportion of iodine is not more than 0.5 per cent.

Cod-liver oil is a remedy which, at the present time, stands in very high estimation; nor does it appear probably that its reputation will be ephemeral. When taken by patients who have become emaciated from any cause, and whose blood is impoverished, it frequently restores the flesh, and, from Dr. Theophilus Thompson's statements, it appears also to improve the richness of the blood. Under its influence, patients often increase greatly in weight, the inscrease exceeding many times the amount of oil consumed during the period. It has been supposed that the iodine and bromine contained in it might produce the beneficial results, but this idea is not tenable, for the effects of these latter remedies are very different from that of the oil; it would seem probable that it acts simply as an oil, and that it is superior to other oils on account of its being more readily assimilated. If the statement of Winkler, prove correct-namely, that the oleine differs from ordinary oleine in not yielding glycerine

Patients often find that after they have been taking cod-liver oil for some time they turn from it with disgust. Why is this? I have already remarked that of all oils the cod liver oil is the most easily assi milated by the system. But after a time the intestines refuse to absorb it, and that being the case it passes through them, and is found in an unaltered state in the faces; thus, by a wise provision of nature, directly the oil is of no more use, a dislike is felt for its employment. If, then, people find that after they have taken cod-liver oil, say for two weeks, it does not agree with them, they should leave it off for about a week or so, then take it again, and so on. By these means the full benefits of the oil will be derived. I trust that these remarks may be of some use to your readers. C. J. H. W.

CARRIAGE WHEELS-THE PHANTOM AND OTHERS.

[207] SIR,-In the controversy on the relative merits of the spider and phantom wheels, which are but differently proportioned examples of Jones's suspension wheels, modified to render them suitable for light vehicles-modification which may be taken as representing the most modern forms of the principle of suspending the weight to be carried from the top of the wheel by rods or chains, instead of supporting it on legs or struts, which is just what wheel-spokes are-in the common way is carried out.

As it is well known that a very much greater weight can be safely supported by an iron or steel rod when that weight is suspended to it than it can safely bear if employed as a column in constant motion, like a wheel spoke, which must not only be incompressible, but also sufficiently rigid not to become bent in use, it follows that so long as it is not employed to communicate the driving forces from its nave to its periphery-in other words, so long as it is not required to act like a cogged or toothed wheel, or as part of what is termed "frictional gearing," but as a mere trailing wheel, and its axle is kept nearly horizontal-a wheel to carry with safety a given weight may be constructed on the suspension principle far lighter than in the ordinary manner.

Suspension wheels have the further advantage of being somewhat cheaper than those with spokes, for rod iron or steel is less costly than spokes, even when the latter are formed by automatic tools (not to mention costly hand labour), as in the case of artillery and waggon wheels constructed for Her Majesty's military service; but, as ordinarily made, they are very unfit from their want of rigidity, in the direction that the driving force is communicated-to act as driving wheels either for locomotives or velocipedes. A driving wheel requires rigid arms or spokes, just as a cogged wheel does, and the only practical question is how the needful rigidity may best be obtained without needless increase of weight.

The usual method in the case of locomotive wheels is to construct the spokes of rigid iron, so that they may not sensibly bend when transmitting the driving force. When this plan is carried out in a velocipede it adds considerably to the weight of the driving wheels, which is a serious objection when it is considered the rider has to lift his carriage up-hill, which he must do when ascending inclines. The "Phantom " may be sufficiently rigid, especially if of moderate diameter; but, if I rightly understand, it has the same defect as the "Spider," viz., that each pair of suspending rods are attached to its nave in the same plane. Now if the rods be short, as in the case of a 36in. or 42in. wheel, they may, if unnecessarily thick, be rigid enough to perform the function of levers, and transmit the driving force from the axle to the periphery of the wheel, without the weight of the latter being made very great, but it is obvious that if the rods are only strong enough to (safely) suspend the weight of the carriage and its rider, they cannot, when each pair is in the same plane, also be rigid enough to act as levers for transmitting the driving force.

To enable a suspension wheel to become an efficient driving wheel, each pair of rods, instead of being in the same plane, should be attached to its nave at a distance apart equal to the nave's diameter; that is to say, in nautical language, attached fore and aft.

All the suspension wheels I have seen, until the principle was applied to our hobbies, alias velocipedes, have been trailing wheels. All cart, omnibus, cab, and railway carriage wheels-excepting the driving wheels of locomotive engines-come under this category; and for railway carriages whose axes are nearly horizontalexcepting when the wheels are so stupid as to run off the metals-I think suspension wheels are specially suited. I have a very strong opinion that when my respected friend Bridges Adams' notions of the advantage of reducing the dead weight to be hauled have come to be appreciated as they deserve, suspension wheels, with mild steel rods, of a quality resembling steel music wire, will come into use, not only on account of their much smaller weight but also because of the great facility of repairing them. Weight is of comparatively little importance on level railways; for a wheel, even if it were a solid disc of iron supports its own weight, and therefore that weight does not add to the force of traction required to haul it; but when we encounter gradients of one in twenty or more, all the weight of the train has to be lifted to the summit level, and this requires more coal than to make it follow its leader on a horizontal line.

It will be understood that I do not propose to make the driving wheels of a locomotive engine on the suspension principle. In them weight causes "bite," and so long as the wheel and rail have to be pressed together it can little matter whether comparatively light wheels are pressed to the rail by a load on their axles or by the weight of the wheels themselves. On the contrary, the heavier the wheel the greater the "bite," irrespective of the load on its axle; so if the driving wheels of a locomotive engine were solid castings, like a pair of iron-edge runners (which one of my men called cast-iron grindstones on the same principle that our Mary Ann says she "biles" unclean garments in her "iron" copper), it would be attended with the advantages of less wear (from diminished pressure in the axle-brasses) and cheapness of construction, for it costs less to cast a heavy disc than to forge a wrought-iron locomotive wheel.

If you think a suspension wheel on the principle I suggest worth engraving I shall be happy to send a drawing. THE HARMONIOUS BLACKSMITH.

TRICYCLE BY H. CHILDS.

[208] SIR,-According to my promise I send you a photograph of a tricycle I have just completed, and am pleased with. It will be seen that the driving wheel is behind; it is 30in. in diameter, and the two front

wheels 36in. ditto; hind axle 7in. long, with 8in. cranks at opposite points. The connecting rods are only in. diameter. The two front hanging levers and pedals, as well as the centre framing, is of wood. It steers easily with the two handles firmly fixed to the front axle. It needs no brake, as it is under perfect control by the feet. The muscular exertion is not at all fatiguing, as the muscles of the body are as well supported as if sitting in an arm-chair. There is a steel spring across the point-axle which takes off all concussion. I can get up any moderate incline with it, and think it would do ten miles in an hour. The distance from axle to axle is 31in.; ditto, between front wheels, 34in. I beg to congratulate you on the success of your journal. H. CHILDS.

ANSWERS TO QUESTIONS.

[209] SIR,-When last doing this I forgot to state that "W. T.," who has had very considerable experience in bushing," i.e., lining with cloth the holes in the butts of pianoforte hammers, has partly written an article on this subject, which I expect will let more light in on it than anything I can say, who on such mere practical details can only shine by reflected light, i.e., mere moonshine compared to that of the original luminary. May I request that my fellow enquirers will in future adopt the advice of Di Vernon to F. Osbaldiston, Esq., and ask all merely practical questions at him instead of at me. He has promised to answer all such arrears in one batch, and not only reply to Mr. Moffat, No. 2640, but "correct"a la tutor-I hope not with a birch rod-Mr. Kemble's odd notions concerning the bushing of innoforte

I cannot call to mind where I saw the engraving of the foghorn which "E. A.," No. 3780, desires a copy of, or would have sent it. It is voiced exactly like the reed trumpet pipe of an organ, excepting the proportions of the reed to the pipe, the former being very unusually large in proportion to the length of the latter, and made stiff enough to bear an enormous pressure of wind.

THE HARMONIOUS BLACKSMITH.

THE 100TH PSALM, ARRANGED FOR FOUR VOICES, BY GEO. COOPER, SEN., CONTRIBUTED BY THE "HARMONIOUS BLACKSMITH" FOR THE ESPECIAL BEHOOF OF THE TONIC SOL-FAISTS.

[210] SIR,-Rarely indeed do I fail to fulfil a promise, but mine to send a familiar tune in this notation, has remained so long unfulfilled that I am not surprised at an occasional gentle reminder. May I hope this will be received as reply to all demands.

in

In selecting "All people that on earth do dwell "not even excepting those savage man-murdering races, the French and German, who have not only ceased to cultivate either social or musical harmonious relations with each other, but have also substituted for them that worst of discords, war-for the purpose of illustrating my old friend's system of musical notation, I have been induced to do so because all people know "All people," and because as almost all people possess "All people' our ordinary complex notation, they will therefore be able to compare that with this, and, if wise enough, to admire its beautiful simplicity. If not people, many people the least among my fellow-readers, will also be able compare this with the popular and much vaunted Tonic Sol-Fa system, which, to my crass ignorance, does not appear equally with this to possess beauty of simplicity, however much of that same article some of the

to

all

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the

advocates of the Tonic Sol-Fa system

selves have manimay themfested.

As regards absolute originality, I fear I cannot

justly claim for my old friend much more than most other inventors have exhibited. His notation, when examined by the light of the experience of those who are accustomed to music by handle, is resolved into a copy of the pins and staples of the barrel of that "horgan" made by the said handle to discourse the "sweet music"

which drives Babbage to

distraction, and compels quiet folk to pay for the privilege of silence, which we then-after this inflicton-do indeed recognize, in the words of the Chelsea philosopher, to be golden. This copy of these staples and pins, written on two staves of five lines each, is neither more nor less than

the notation before BASS STAFF the reader.

TREBLE STAFF

The idea of writing the notes or signs of the sounds uttered when the black keys are depressed on the lines, and those uttered when the white keys are struck in the spaces between the lines, for the purpose of avoiding the necessity of using signs for sharps, flats, and naturals in music, written for keyed instruments, with fixed intervals, is no novelty. If I am not much mistaken, it was done in the notation published by a reverend gentleman, whose name I forget-I think construction of apparatus which recorded musical perthe same person who also anticipated Hawkins in the formance on keyed instruments. About forty-five years ago I saw this notation engraved in an early vol. of the Phil. Trans., date about 1680.

Anything simpler or more easily impressed on the mind of the intelligent tyro than that all the notes are of the same form, and the fact that the length of any one note in this system expresses its temporal value, it would be difficult to imagine; but this peculiarity, how

ever valuable, cannot be properly termed an inte -it is rather the observations of an existent fact. A the lengths of the staples in the organ barrel mine the time each of the pallets is kept open, K consequently the durations of the sounds of the so a mere copy of these staples on paper show relative lengths, and must have indicated the t each note to so appreciative a mind as Hawking ba To those of my fellow readers who can sp beautiful harmony I especially recommend this a ment or setting of the "Old Hundredth for t voices, in which the bass voice sings the scale in contrary motion. For the manuscript at gem, which is by Geo. Cooper, sen., late St. Paul's Cathedral and St. Sepulchre's Chand la indebted to the kindness of my friend and fe spondent "W. T.;" and I trust all my mome readers, not excepting Dr. Ussher, from when abe heard but very little of late, to our sor pleased with it.

THE HARMONIOUS BLAC

FRUITLESS LETTERS.

[211] SIR,-Would you have the kinda me through the MECHANIC, or by letter, a can recommend that makes the best se adapted for dress making and general p you will greatly oblige me?

Kearsley, Aug. 2nd, 1870.

[We frequently receive letters like the s we never on principle give the information va We think that a publication devoted to s cation, or, in fact, any other kind of educatio never recommend the goods of any partieni facturer. Weak journals may, and frequdy au things "for a consideration;" but strong should be, like Cæsar's wife, "above suspense all events it is useless for any one to write a = letters as the one above.-ED. E. M.]

MAMMOTH.

[212] SIR,-Only two skeletons of the mammoth or Be phas primigenius, are existing, I think muses the mammoth of the Lena,at St. Petersberz and the mammoth of Lierre, at the Museum of Natura History at Brussels, another specimen was discoveria 166, near Tomsk in Siberia, and a commissa Las been named by the Academy for the purpose of a removal to 8t Petersburg. I saw the magnificent son of the mammoth of Brussels some months ago, and a fr particulars of its discovery may prove interesting.

In the month of May, 1860, when constructing a cam near Lierre (province of Antwerp), the work buried in the sands the skeleton of a gigantiz this skeleton was lying on the right sir, the column very much bent; the head was entre, and a was also a tusk of enormous dimensions; nei ribs of the left side were missing, and several a were broken, or rather discomposed. M. military physician, recognized that it

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of a mammoth. He had all the bones at
they had lost their solidity; the head of
weight, split and separated into numets
some other bones also suffered from the extra and
in the transport.

These ancient remains, deposited in te aan d Brussels, deteriorated every year until the ses direct Dr. Dupont-so well known by his investigates in th Belgian grottoes-undertook to restore them. Hva aided in this difficult task by Mr. Dapann, od= auxiliaries of the museum, who gave proofs under the circumstances of great skill and perseverance. After months of laborious exertions the mammoth of L was entirely restored in the action of walking

The height at the nape is 3m. 60; the height of 2 Indian elephant, of which an adult skeleton is existing at the Museum of Brussels, is only 2m. 6 head weighs 250 kilogrammes, and the tusk mas 2m. 90, following the curve.

The restoration presented great difficulties well as the restoration of the missing bores skull had been reduced into more than 200 fragme nearly a third part of the skeleton was wanting had to be carved in wood; the humerus, for what museum did not possess all the requisites, could on restored by the study of another humerus belong the University of Ghent; one of the tusks is arti one tibia and one rib do not belong to the same a but to an individual of the same species, height.

age.

The manner of putting together the mamm Lierre deserves special attention. In some zooles galleries the bones are perforated, and are attaches gether with iron wire, and so rendered motionless. mammoth of Brussels has not a single bone perfec By means of some adjusting screws every bone cas taken away and examined. The whole of this enor skeleton can be taken to pieces in 20 minutes and up again in less than one hour.

For other particulars on mammoths, especialis that of the Lena, see Intellectual Observer, Febras BERNARDEN. 1867, page 70.

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AUGUST 12, 1870.]

ENGLISH MECHANIC AND MIRROR OF SCIENCE.

a good many communications, and have undertaken to report the doings of the scientific societies-not to It mention reviews and extracts from new books-I cannot help thinking you could well occupy more space. goes against the conscience to buy for 2d. what is honestly worth 3d.; but, commercially, it might be advantageous to enlarge both number of pages and Your present capacity is hardly the price at once. large enough for the journals and their contributors which you have absorbed, not to mention one or two others which may be absorbed. So I cannot help thinking that the sooner you relieve our TENDER consciences from the reproach of receiving more than an equivalent for our twopences the better.

THE HARMONIOUS BLACKSMITH. [Though the "Harmonious Blacksmith" is not the

As to

only one who has made a similar suggestion, we think
it right to say that we have no idea whatever of in-
creasing the price of the ENGLISH MECHANIC.
its size we do not know what it may grow to: much,
The method is this: After the wall is covered with
however, will depend on the activity of our constitu-
It is possible to the second cont of mortar-one lime and two fine
ency, of readers and subscribers.
permanently increase it eight pages without any washed sand-the wall is left to dry perfectly. The
Let us have three subscribers colours are ground in pure water only, and applied with
increase of price.
where we have now got two, and it shall be done.no other vehicle than water; the same colours are used
as in fresco, no vegetable colour is admissible; when
ED. E. M.]
painting, the surface is first wetted to displace the air
from the pores, the colours are worked into each other;
when all is finished, the colours are only on the surface
and will not bear to be touched; the whole painting is
now fixed with water-glass solution in a diluted state,
after it is done with the brush.
I
the solution is applied with a syringe for the first time,
The above is only an outline of the method, but if re-
quired, and with permission of our kind Editor, a detailed

the second coat, "intonaco," is floated all over the wall,
about 3-8in. thick, firmly pressed down with the
dry the face of this last coat is rubbed down with sand-
trowel only; it is then left to dry. When perfectly
stone to remove the thin skin which has formed on the
surface; this thin skin removed will leave the wall quite
porous, and now the painting may begin, by first satu-
rating with soft water as much of the surface as can be
painted in a day; it is also well to keep the edges wet for
the next day, when the same is repeated until the whole
In this method the joins are avoided. But painting
wall is finished.
also sometimes called water-glass painting, a method
in fresco is now superseded by stereochromic painting,
which gives the artist perfect control and freedom over
his material. One may work a painting over and over
can master the details at once; besides the work is more
again until the desired effect is produced. An artist who
is used to fresco, to body colour, or distemper painting,
durable than fresco; the two large pictures in the House
of Lords are executed in water-glass medium.

CHEMICAL FLORICULTURE.

[214] SIR,-The three primary colours, red, blue, and yellow, are not to be found pure in any species of We have red and blue in fuchsia, but no flower. yellow; yellow and red in the rose, but no blue; blue and yellow in the heartsease, but no red, and so on. mean, be it understood, decided primary colours, and not secondary. As this seems to be a law of nature

that sets the art of man at defiance, we may expect blue dahlias, yellow geraniums, and scarlet pansies when the circle is squared, but not till then.

DAN ROSEN.

TEMPERATURE OF JULY.

account will follow.

THE WELSH SHEPHERD.

CURIOUS SENTENCE. [219] SIR,-I am attracted to this topic (p. 423, letter 92; and p. 469, letter 164), by my having a The central letter, as I always different reading. Meaning, (sator) the sower (arepo) of [215] SIR,-I send you my record of my 2ft. ther- knew the passage, was not R, but N: Sator arepo tenet mischief (tenet) keeps (opera) his works (rotas) on It was, in old times, the schoolwheels, or a-going. boy tradition among my comrades that Arepo signified of mischief; the same word occurs in the (venerable!) nursery rhyme:

mometer below the surface last year and this:

1870.

1869.

July 1-2

57°

July 15

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On 1st July there was an earthquake at Santorin. Why did the temperature fall on the 3rd (or say the 2nd, these observations being at 8 A.M.) and then rise? C. J. R.

THE SYMBOL #, CONIC SECTIONS, ETC. [216] SIR," Gimel" should have told us he wrote "He knows all "to argue," and not for information. about the matter," he now says. Apparently, however, he does not know that a ratio is but an abstract of course. quantity. Todhunter is quite right, Gimel" might as well say that the symbol 3 does not invariably represent the number three, because it also represents the number of angles in a triangle.

I should regard "the section produced by a plane passing through the vertex of a cone" as either two intersecting right lines, or one right line, or a point (according to the position of the plane), not as a hyperbola. One may, if one so chooses, speak of a circle as an ellipse, whose eccentricity is zero; of two intersecting lines as a hyperbola, whose axis is zero; of a right line (or rather two coincident right lines) as a parabola, whose latus rectum is zero, and so on: but I do not see the sense of RICHARD A. PROCTOR. it myself. P.S.-Todhunter and the Symbol .-Todhunter is right, of course.

MOTIVE POWER FOR VELOCIPEDE.

[217] SIR, I cordially join with Thos. Stanhope in hoping that some of your talented correspondents will be able to design a useful, safe, and moderately priced steam velocipede. I have read with the greatest attention and interest every new description of bicycle and velocipede which has appeared in your journal, each one professing to be the easiest and best ever invented; still I am as much at a loss as ever as to a selection of the most practically useful machine for a man who is too old to care either for the excitement of a little danger, or for too much physical labour, but who would gladly make use of some means of locomotion for his daily journey to business, rather swifter than his own feet, and rather less costly than a quadruped. Is it too much to look forward to the time when every road will be a tramway, and when steam carriages will run on them without any danger or inconvenience ? and can we not "educate" the public in this direction by a "pioneer" steam velocipede ?

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opera rotas.

One-ery, two-ery, six-ery, seven,
Arepo, crackabo, ten and eleven;
Pin, pan, musky-dan,

Twiddledum, twaddledum, twenty-one.
Arepo is probably a bogie word; it is of Syriac cut, and
of eastern origin. The Mohammedans have a grea deal
about Araf, the partition between hell and paradise,
see the Koran, heading of chapter vii.; Araf being
We must not be
much the same as Erebus; thus arepo might possibly
mean deeds of darkness or mischief.
too severe on the classical Latinity of the like; the pas
sage affects to be an iambic trimeter verse, but it is
The best known is:
merely a monkish amusement.
Roma tibi subito motibus ibit amor, i.e., Rome, on
thee suddenly with its emotions shall come love. This is
by Sidonius Apollinaris, a Christian writer, A.D. 482.
A medieval toy of the kind was: Sacrum pingue dabo-
non macrum sacrificabo, which is an hexameter, mean-
ing: I will give a fat victim, I will not offer a lean sacri-
But the same read backwards
fice-alluding to Abel.
by words is Cain's offering: I will sacrifice the lean, I
will not give a fat victim; and this is a pentameter.
Such a quaint conceit was called the Palindrome, or
The latest play of the sort I know is
Sotadic verse.
that Mr. P. G. Hamerton writes capital letters from
GIMEL.
abroad to the Globe newspaper, and signs his name G.
P. Notremah.

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[221] SIR,-I need scarcely say that I have been very much interested in the articles on zymotics which have recently appeared in the ENGLISH MECHANIC, Dr. Vanderweyde introduced the subject by showand, as a further contribution on the same subject, Í send an account of a discussion at a recent meeting of ing and explaining the device, as applied to his own microscope, for conducting the examination. Firstly, the Polytechnic Club of the American Institute. used in microscopic investigations, but set in a perpenthe liquid was placed in a cell, not such as is ordinarily dicular position, so that the light may be passed through it in a horizontal direction; the light from refraction and reflection, direct through the eye-piece the cell is refracted and reflected by means of a prism many annoyances of former venient, and up the tube of the microscope, and then, by another in a horizontal line to the eye. This is very conmethods. Formerly, doctors had little faith in the revelations of the microscope, and scouted the idea that some diseases were originated by animalcula—as the itch and some others.

saves

The researches of Hallier, the great microscopist of Jena, were referred to, and his conclusions with regard to the germs found in the bile of cattle dying of the Texan cattle disease stated at some length. This Texan cattle distemper answers to the yellow fever in the human system. In the bile taken from these cattle were found germs which not only lived, but grew and course of growth in the yeast plant was then traced, increased after the manner of those in yeast. The and the resemblance of the other germs pointed out. illustrated by fine drawings, that their development was very largely influenced by the circumstances in which they were placed, one form being found when In regard to those found in the bile, it was stated, and the growth was in carbonaceous substances, and another very different one when in substances containing Another interesting fact was then stated, nitrogen. showing a very close resemblance between the highest developed form of these plants or germs and those sulting from close study of these germs All animals, during their found in syphilitic diseases. Further developments relight upon the development theory, as well as the dif ferent relations of animals. development, go through the forms of all classes of animals below them-the impression of the parent alone deciding how far this development shall proceed.

may throw

The cell that causes the fever and ague has certain necessities of growth, as stillness of air and certain conditions of soil. This cell, or germ, when taken up with the breath, produces the fever. It does not rise any great distance from the ground, and hence the greater danger of sitting than standing in places where it abounds. The state of the body has much to do with the effect of the germ upon the system. When, after the danger is much less than when the stomach is a full meal and in good health, exposure takes place, empty and the system tired and exhausted. It will probably be proved that all contagious diseases have a common origin.

The use of the spectroscope has done much for science in the analysis of liquids. The two absorption lines of blood, in spectrum analysis, give us the means of distinguishing blood from any other substance, and showing the presence of any foreign body in the same, as they are never confounded with any others; no two bodies ever producing the same spectrum. In typhus fever the blood discs appear broken up, sometimes flattened and a disc half gone, as though cut in two. We find some poisons useful in disease, and their action may be attributed to their destroying these cells, or their arresting action, as, for instance, carbolic acid in and internally, it completely breaks up the disease. small-pox, where, properly administered both externally The effects of arsenic eating are possibly due to the destruction of organic growths in the system, rather than its arresting waste.

For small-pox Mr. Nash considered warmth, cat[220] SIR,-I will, with your permission, make a few critical remarks on this subject, also with reference mint tea, and Saratoga water about the best things; Inductorium." First, the tension of society is that people think that two sets of facts canto the ingenious method of construction given by your and Mr. Edwards said that one of the great errors of correspondent the electricity or length of spark depends on the not be true at the same time, when both of them are number of windings of the secondary wires (cæteris true; for example, we are prone to think that either paribus). In my opinion, if tension is required, the the chemical, the electrical, or the germ theory of disBy this method, the number of all be correct. In the fearful epidemics of 1853, he induction coil should be made longer, keeping the ease is the true one, and the others false, yet they may were the ones that escaped. As the disease extended, windings and length of spark would be proportional to found that at first the strong and healthy were attacked, As an in- all were attacked, and finally the negroes, who had the length of wires. To obviate the inconveniences of and those that had been sick, or were just recovering, spools of great length, large coils might be divided into stance of low tension, considering the length of wires always braved malaria, both in Africa and in the South, sections, and combined in a compact form. used (viz., 150 miles), I may cite the coil at the Poly- fell victims to it. Those who recovered always had technic Institution, which with full battery power gives been under such treatment as would keep them from A spark 4in. in length, has been getting out of a perspiration; and it was the old nurses only 25in. sparks. obtained from three miles of secondary wire; therefore, and negresses that understood this treatment, and were if the diameter of such a coil were kept constant, and successful, while the faculty failed. be obtained. The following, I think, proves the cor150 miles of wire used, sparks of 16ft. in length would rectness of the above reasoning. If two coils giving 4in. sparks be combined, and the current of the battery If any of your readers detect a flaw in the above be kept constant, the combination will give 8in. sparks. reasoning, I should be glad to have it pointed out, and also to have their opinion (perhaps I may include "Sigma ") on the subject.

May I ask "Inductorium," whose method of construction I like, if he has tried the effect of 5 or 6 cells on his coil? which, I have no doubt, would give interesting results as to length of spark; also, did he succeed in winding the wire in regular layers in so confined a space as in. between the discs.

S. T. PRESTON.

In the course of the discussion upon the several theories of disease, Mr. Root enunciated his theory of the circulation of the blood and the power of the muscles, which was, briefly, that they acted through shortening them. Dr. Vanderweyde considered that the pressure of the blood within them dilating, and so this was disproved by several well-known facts, as the elasticity of the arteries, which, by their expansion and contraction with the beating of the heart, prevented the transmission of power in this way; also the fact that the blood was only transmitted through the walls of the capillaries by endymosis, and not by pressure.

I enclose the account as it has reached me, believing that it will be interesting to our readers in general, and J. T. W. those interested in microscopical examinations in particular.

GAS.

[222] SIE,-I had no intention of being discourteons to "C. D. C.," but when any one attacks other people, even though they are united in the form of a "Company"-which is too commonly regarded as a legitimate object of plunder and abuse-he must expect to get attacked in return; and when any one picks up a foolish and most unfounded charge, and supports it by instances equally unfounded, I, for one, scarcely think it is discourtesy to warn his readers that his knowledge of the subject is too seant to justify them in accepting his statements, for he invites this by setting forth these unsound remarks. For myself, I have not the least personal interest in the matter, as "C. D. C." supposes, but I do know what is the truth; and I do know, from years of acquaintance with gas engineers and gas directors, that as full a sense of right and as thorough a desire to do justice to their

customers pervades that class as is to be found in any commercial body or individual; and having watched many of the squabbles got up by interested parties, I know that the cry against the companies is pure clap

trap.

As to the manufacturing part of the question, I spent three years, not long ago, in one of the largest London works, with the intention of taking charge of a works; therefore, I am fully able to assure your readers that the notions set forth by "C. D. C." (taken up as they are from people who know remarkably little of the matter, though making much noise) are entirely erroneous. He says (p. 448), I am bound to prove this assertion, and I proceed to meet his desire. The point at issue is the alleged removal of illuminating hydrocarbons from the gas, because the companies "find it expedient"-a phrase which certainly implies that they do so for reasons not covered by the necessities of manufactories. Now it is not even true that the illuminating power is reduced thereby, for the simple fact is, that the gas, as it leaves the retorts, is totally unfit for combustion as a light-giving agent. It burns with a lurid, smoky flame, and is heavily charged with sulphur and ammonia, both of which the companies are bound by law, under heavy penalties, to remove. There is no known process for removing these which does not also remove some of the light-giving materials; therefore, any reduction of the real illuminating power belonging to the gas, after the tar and condensible vapours are allowed to condense (which they must do, or they would choke all the pipes) is imposed on the companies by law to their great loss, for a little common sense will tell any one that it is their interest to keep in the gas all the power possible.

Following down “C. D. C.'s" letter, I do not class Letheby, Frankland, and the others named as gas quacks; " nor do they join in the senseless gabble the real quacks utter. They watch and endeavour to keep down those irregularities of manufacture due to the inferiority of materials and carelessness of men met with in all manufactures, and which the gas managers themselves are as desirous as any one to d minish.

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EXTRACTS FROM CORRESPONDENCE.

says:-"In

BRASS INSTRUMENTS.-J. Samuel
almost every public work in the United Kingdom there
is a brass band, and there are generally some members
who are mechanics, and most of them take in the
ENGLISH MECHANIC. NOW, I think it would be a great
boon to them, as well as me, if some well-learned brother
reader would write a treatise on all the different kinds
of brass instruments and best makers; something
similar to what Mr. Hermann Smith is writing about
the harmonium."

GAS BY A NEW PROCESS (p. 474,1. 185).-"Gimel"
says: "Let me add my earnest trust that this may be
described in a practical way, so that it may be tried.
To say nothing of gas light, I can testify that one of the
most delightful comforts is the gas fire, which you can
have blazing, or low, or out, at pleasure; but it is very
expensive."
SETTING OF VALVES.--" Paul Pry" says:--"Although
the editor has not formally given Mr. Baskerville leave
to contribute a series of papers on the setting of valves,
I hope he (Mr. Baskerville) will do so, nevertheless.
Such a contribution, especially from the pen of Mr.
Baskerville, would greatly enhance the value of the
ENGLISH MECHANIC to a very large section of its
readers. In the mean time, I should be very glad to see
a letter on the subject of the expansion valve as an
auxiliary to the slide valve, explaining its action, and
the method of setting it."

A note offering space was appended by the editor to
Mr. Baskerville's last letter, but was omitted in mistake

by the printer. Mr. Baskerville has since been written
to, and he will in all probability contribute the offered
papers.-ED. E. M.]

SPEED OF CIRCULAR SAWS.--A correspondent of
the Scientific American says:-"It is laid down in me-
chanies that the speed of a circular saw should be about
should run 9,000, or a little over that number of feet
two miles per minute-that is, the periphery of the saw
per minute. Having had much experience in the build-
ing and the running of saw mills. I have found that a
greater speed could be used with safety, of which I will
give an example, a mill that I finished and put in
I was in nowise
operation about eight months ago.
trammelled, and everything was left to iny direction,
which gave me an opportunity of testing a very high
speed, together with a heavy feed on a large saw.
The size of the Building was 34ft. 100ft., and two
stories high. Size of engine, 15ft. 30ft. x 82ft., with 83
revolutions per minute. Three cylinder boilers, 36in.
diameter 30ft. long. Flywheel, 20in. face 12ft. dia-
meter: weight, 8,000lb. From the flywheel, with a 20-in.
belt, is driven a 4iu. counter shaft, with a 4ft. pulley.
A 64ft. pulley on counter shaft, with a 16in. belt to a
ft. pulley on saw mandrel, drives the saw, which is
66in. diameter, running 800 revolutions per minute-
14,0001t, per minute-which is about 5,000ft, per minute
over the standard. With this very high speed the saw
cut Sin. to the revolution, making a 3in. feed, and in
one day of twelve hours, 97 logs, producing over 31,000ft.,
were cut."

PREVENTING THE CLOGGING OF BOLTING
CLOTHS.--" An Old Miller," writing from one of the
agricultural states of America, says: "A good method
of preventing the clogging of bolting cloths consists in
thoroughly cleaning them, inside and out, as well as the
bolting chest, and then passing the flame of burning
alcohol rapidly under the whole cloth. Extreme care
should be taken to avoid damping the cloth."

་་

REPLIES TO QUERIES.

IN their answers, Correspondents are repe requested to mention in each instance the te number of the query asked.

[2687.]-DUSTING BRASS MOULDS.-1bes 1 mit the following:-For light work, face you with the following: 3 parts new sand, and 1mix it up as you would facing sand and face you with pea-meal. For heavy castings mit SALT sand, 1 part old, and 1 part dried loan your pattern with, and face your monii w meal. For dry-sand work use S parts dry, new sand; and for facing your dry-sand mock te with, use lime; mix it in water the same would black-wash. If Ironfounder" will fo

instructions, he will find that "S. L.," who are

query, is quite wrong. If "N. L.," ha- been asl
casting, he must know that coal dust is adg..
In the first place, bres is d
brass work.
searching nature that it would eat its way to
casting would be what we call struck all
if he used black-wash for his cores and e
brass would fetch it all off and leave it tai
castings, as black-wash cannot withstand's ent
brass on its surface. Lime is the only
withstand the action of brass; and lastly, teat
or blacking are used for brass work. it .
look a nasty black colour, almost the sam
W. J. W.

lameness in horses I take to be no new
[2756.]-LAMENESS IN HORSES.-HesTM »?
during 1868-9 I obtained from some extensive e-
that were making a few miles east of Londo
other things, a quantity of horse shoes, s
solid and heavy, similar to the one figured in
CHANIC of July 29 (which from the depth the
which if used for lameness, then the ene figures...
found at must have lain there several hundr
be an invention, only a revival. I have about tand
of early horse-shoes, all very different from thest
in use; also some old bits and spurs. To any
terested in these things I shall have much pers
in showing them-A CURIOSITY COLLECTOR.

[2756.]-LAMENESS IN HORSES.-"Country Vet

in reply to J. C. Duffryn, advises bleeding in the se
stages of Laminitis (fever in the feet. In the majest
of cases the disease consists of congestion of the entir
venous circulation of the foot, and it may remain in that
state for days without taking on inflammation. My
treatment is to remove the ordinary shoes, and imine-
diately apply the special ones, not seated or bevilled,
but bearing the whole width on the less on the wall.
unless the sole happens from being pared to be thi.
Give a dose of from 3 to 6 drams not onnces as stated
according to size of animal, which must be compell Sty
take exercise on soft or wet ground if available, seve
times daily. Should the case be a very acute one ca
water may be applied during the intervals of cores
and also ten drops of Fleining's tincture of aconte
be given every hour until the animal is relieved
aloes may be repeated in about three days, if
or any lameness remains. The majority of th
are relieved in two or three days. I never be ==
stage of the disease.-T. D. BROAD.

Next, as to the dividends, I must point out how [3766.] - TO CLEAN, AND FILL, "C. D. C." betrays his real unacquaintane with the subject and the source of his supposed facts. The BAROMETERS.-Buy a glass tube closzk 34in. long, small or large bore as requi42* companies are limited to dividends varying from 7 to with a fine rod with rag or the small 10 per cent. Will any one say this is too much for a pipes (tobacco) to be had at any cigar shop. Fo4 2 trading profit when any day some new improvement THE RIGI RAILWAY.-A correspondent of the mercury at any wholesale druggist's, price à LA might even supersede gas and destroy the capital Engineer, writing from Fitznau, thus describes this crown per pound. Make a funnel of clean wine??? invested? Remembering also that for very many novelty in railways:-"Immediately after leaving the and pour the mercury through repeated'sheets 2005 or vessel, until quite clean; then insert a chastit years the companies scarcely had any dividend at all station-yard the ascent is commenced, and in about 100 till improved manufacture-notably the use of claylieve, terminate only at the summit. The rails, which or 150 yards the incline of 1 in 4 begins, and will, I be- paper with a fine hole into the tube, pour in quarter of an inch of the top; take a clear retorts, and common-sense business arrangements are very light, are laid down to what appears the ordi- and stop up with the finger, reverse and keep limiting ruinous competition-were adopted. But nary gauge; in the middle is a wrought-iron rack rail of the air bubble up and down till clear of specie "C. D. C." says, and "the bonus in addition, to avoid about 4in. or 5in. pitch; the rails are laid on transverse then fill up. Buy a boxwood cistern (or better a the letter of the law"-again an imputation of dis- sleepers, and outside the rails, longitudinal beams are yourself), and fit it on the tube before with glue aDE STA honesty. Now the simple fact is, no company can bolted to the sleepers. The locomotive, "Stadt Luzern if too loose, unscrew the end with the sheepsi declare a bonus, and any one can stop their dividend by name, has (when on the incline of 1 in 4) a vertical and fill up, then screw on, and the tube is inad by showing to a court of law that it is in excess; but boiler, the cylinders are 11 in. diameter, and 16in. stroke; looking at the cistern of any mercurial baromete the law permits them if in any years they do not they are outside, and are parallel to the rails. The idea is soon got hold of. Adjust by a good rule, sa make their full dividend in any subsequent year being outside the crank pin. As is very often seen on valve motion is of the straight link kind, the excentrics good barometer of a friend or public institution. 7 work may be made to fancy. A screw at the bott 27 within six to make up that deficiency, and some of the Continent, the machine is supported on four wheels; enable the mercury to rise to the top, so as to be e the companies have been able to do this, not as a their diameter is, I should think, about 2ft. 4in.; they are about without risk. My advice to amateurs is, Ja bonus to evade the law, but openly and legally as loose on their axles, the rack wheels are keyed on in the make many, as the fumes of mercury are very injur arrears given them by the law. middle, and one axle is driven by the engine by spur-far better purchase.--GEORGE MACRAE. gearing, the engine making three revolutions to one of the rack-wheels; the axle which is not worked by the engine has two friction wheels keyed on it for the brakes to press on, and the brake on the only truck I saw was of the same sort." The writer saw a truck containing about 4 tons "pushed" up the incline at the rate of four or five miles an hour.

As to carburetting, I have not the slightest intention of disputing about a matter which scores of patentees have tried at. By all means let any one try it who likes-as I have, and many others. The simple fact remains, as pointed out by another contributor, that after a great flourish of trumpets, and many statistics showing the great profit of the process as used in the city lamps, it was abandoned; and the general public steadily declines to patronize the many patented plans, and giving my opinion simply as my opinion, I consider it does so very wisely.

I find I have omitted one argument, which, as it is based on truth, must not pass. It is quite true that ording to the mode of working a larger quantity may be obtained from the coals but of inferior quality. This is just one of the questions of manufacture and cost-the best way to obtain a gas of the power required by law. If the heat is very high or prolonged, more, but poorer, gas is obtained; and to compensate for this a certain proportion of rich and costly cannel coal must be used. What has this to do with the public, or how are they wronged? The company is bound to give them 12-candle gas, making it how it pleases. As a fact, the companies do supply 13 and 14-candle gas, as Messrs. Letheby and Frankland show by their reports; and this is the way the "public

suffer."

SIGMA.

Filters filled with black oxide of iron are said to be very effectual in removing organic matter from impure water.

The

[3815.]-EMERY WHEELS.-The expressed (oil · 1 seed, like several other vegetable oils, but in a ge degree, is capable by exposure of absorbing a amount of oxygen. It is this property of linseed which renders it so valuable for mixing with piger as it is this gradual absorption of oxygen which. the oil, and produces the phenomenon of drying. EYE-LOTIONS.-A correspondent of the Lancet calls paint. For this purpose linseed oil is put through attention to the dangerous practice of would-be philan- process of boiling with litherage and oxide of lead, " thropists giving away eye-water to all applicants without which it absorbs so much oxygen as to promote itreference to the real nature of the particular disease. ing properties. In this condition it is styled "boile He thinks, however, where it is confined to the sulphate seed oil." This peculiar property of linseed oil rend of zine lotion little harm is done. "The old family it very valuable in certain arts, as by continuing the ox recipe for eye-water, if inefficient, is generally very inof- tion by prolonged exposure to the atmosphere it assura fensive; it is strong of the water; and if it does no good it the appearance and character of india rubber, be does no harm to any one, and produces little visible effect. very tenacious and durable, which any one can per It contains neither lead nor belladonna. In ninety-nine in the durable qualities of ordinary wax-cloth. cases out of a hundred it is a very dilute solution of sul- emery wheels are formed of clean emery compon phate of zinc (white vitriol, so calied). Water, alone, with just a sufficient amount of boiled linseed oil, for the eyes is an excellent sanatory appliance, as fre- mixture being agitated for a sufficient period under quently, perhaps, as it is for general purposes of health.posure to a considerable temperature and a free acus But as simple conjunctivitis or catarrhal ophthalmia is of atmospheric air, or some still more powerful ovi the most frequent of eye complaints, a little sulphate of ing agent, can be made to assume the necessary de zinc is thrown in on speculation. It sometimes does of tenacity, and whilst warm, being exposed to hyd lic pressure in a suitable mould, and subsequent dryi good, it is very cheap, and it manifests its presence even We generally use too in a stove, the emery wheel is complete.--MATRIX. in so great a quantity of water. [3851.)-HARNESS.-" Saddler's" reply would hav much water in our collyria. It was a valuable hint to me some time ago, when a distinguished foreigner ob- been valuable some years back. I will give served that our strongest (he was speaking of sulphate advice and experience. If you use a "composit, n of zinc-two grains to the ounce of water) was only the your harness will require constant applications of oil an strength of their weakest lotion. But if one did not dye, and scraping-the former to keep it supple know when to prescribe or to omit sulphate of zine, or black, the latter to take away the cracky appearanc sulphate of atropine, or other common lotions, one could I find Clarke's harness blacking far preferable to an r only be safe by great dilution, and also perhaps by com- ceipt I ever tried, and I am told it contains the righe pr binations of different remedies." portions of oil, dye, and polish.-NOT A SADDLE

[3949.]-GUYANA OR GUIANA.-These are three colonies, belonging to the British, Dutch, and French, of this name. They are situated between longitude 5130 and 61° west, and latitudes 1 to 8 30 north. Venezuela lies between longitude 60° to 73° west, and latitude 2 to 11 north. Your correspondent "Beruardin" in mistaken in saying they are to north of Venezuela, such being impossible, since the Carribean Sea washes the shores of Venezuela on the north. The climate here is very unhealthy for Europeans. Demerara being the capital of British Guiana, the most westerly and adjoining Venezuela.-J. G.

[S952.]-LOAM PANS.-Having been troubled the saine as" Inquirer," I discovered that there was too uch clay in the loam, and after the mould was blackwashed and smoothed over, I came over it all with barm, or very stale beer, put on with a very fine brush; this has the double effect of staying it from veining, and the blackwash from scaling.-N. L.

[3982.]-SOAP-MAKING.-Some valuable information on this subject is to be found in Dr. Ure's" Dictionary of Arts and Manufactures."-BETA.

[3982.1-WORKS ON SOAP-MAKING.-" Campbell Merütt on Soap and Candles," cost about £2: "Ott ou Soap: Taking," cost about 10s. 6d.; "Kurten on Soap-making," Cost unknown. All to be got through Trübner & Co. The two first are the highest authorities on the subject, and zare exhaustive and well illustrated; the last is good and ractical, but the translation (from the German) is aulty, many errors in substances, measures, and weights, which would puzzle a novice, though not diffiult of correction by a practical hand at the trade.-D. G. [4020.]-WOULFFE'S BOTTLE.-Let "M. P. C. S." Chuck a piece of ordinary brass tube in a lathe (say) 2in. or 3in. long, and its external diameter slightly less than the internal diameter of the neck; now, whilst the tube is in rapid motion, press the part requiring to be cut out gently against the end, using emery and oil, or fine sand and water, as a cutting or abraiding medium. It will be found a great advantage if he can manage to apply the pressure through the medium of a piece of india-rubber held against the inside of the bottle; this will cut it out quite clean. The same plan is applicable to cutting the central hole in electric dises, &c. A very neat application of it is to cut openings opposite to the winding centres of shade-covered pine pieces; these openings can be protected by inserting a small brass bush or ilet with a little white lead, a great brass plug being used to keep out dust. Under those circumstances the shade never requires to be lifted, as the winding, &c., can be effected by the application of a suitable key.-MATRIX.

[4022.]-TUNING BELLOWS FOR HARMONIUM. -See "Eleve's" letter, p. 186, ante.-SAUL RYMEA. [4042.]-MAGNET.-Nos. 16 or 18 would answer.

SIGMA.

chief merits are-first, a complete scale; second, a single
sound to each key, whether drawn out or compressed,
thereby dispensing with the the thumb-bellows of
German concertinas. I have heard very difficult music
excellently performed on these instruments by Mr. W.
H. Birch, of Reading, who is, I believe, musical editor
for Boosey & Co., Holles-street.-J. NASH.

[4096.]-SODA WATER.-TO" F. C. S."-Tell me if
two strong-hooped barrels would stand the pressure;
and what material the bottling and corking apparatus
should be made of: and what length of time it would
take to impregnate the water with the gas; and what he
means by a washing vessel between? Any information he
can give will be thankfully received. I tried the un-
slacked lime, and it was quite a failure, which I knew
it would be.-D. W. L.

[4102.]-GALVANISM.-Dr. Althaus's work is, perhaps the best on medical electricity, price 15s., obtainable through any bookseller. My next paper will deal with the galvanometer question.-SIGMA.

[4121.]-BOTTLING FRUIT.-Take any quantity of fruit that is sound and fresh; fill your bottles; fill a copper nearly full with cold water, with a board at the bottom; put the bottles in, up to their necks in the water; put it on the fire, and let the heat get up to 150 degrees; let them stand at that heat for twenty minutes, then take them out, and fill the bottles with boiling water; then bung them, and tie with a bladder, and they will keep any length of time if kept air-tight.-D. W. L.

[4136.]-EGG-HATCHING MACHINE." P. G. M.," who asks for information in detail on this subject, will find an illustration of Pinchen's Incubator on p. 108, Vol. X., of our MECHANIC. It has, I believe, been found successful. According to M. Réaumur, all that is required is a heat of 96 Fahr. Eggs kept at that temperature for the requisite number of days will produce chickens. Mr. Cantelo, however, who some years ago exhibited what he called a hydro-incubator, asserts that the proper temperature is 106 Fahr.; and if this heat is sustained chickens will sometimes appear on the eighteenth or nineteenth day. His machine was capable of hatching from 100 to 600 eggs; and its principle consisted in allowing warm water to flow along plates of glass placed over the eggs. The Egyptian and Chinese systems are much the simplest, as in these the eggs are merely placed in trays of sand or bran, and kept in ovens or on heated iron plates. It is very doubtful whether any system can be made profitable in this country.-SAUL RYMEA.

[4144.]-FIRECLAY BAKING.-The raw fireclay is usually mixed with one-third its weight of burnt fireclay termed "grog," or powder of old glass pots from which all the clinker, &c., has first been carefully removed. Sometimes a certain proportion of sand is added, or clays, other than Stourbridge, according to circumstances and the purposes to which the clay is to be applied. This mixture is moistened, kneaded, and let stand for some time; often a fortnight or three

[4044.]-AIR GUN.-The drawing represents the lock and breech screwed together. A A lock, B spring, C trig-weeks, receiving occasional kneadings in the meantimey ger, D tumbler, E sear, F F push pin, G trigger spring, H sear spring, III seats for the upper plate, removed to show the construction. The trigger and scar work on studs riveted into the plate, and prolonged through the upper plate, screwed down by a single screw, which also serves to check the motion of the sear. J section of breech, K valve, L brass tube. The valve rod within this tube has a spiral spring along its length to keep the valve to its seat; the valve is best made of bullock's hoof. The lock is represented ready to be discharged., The barrel-not shown-is on the other side of the

the longer you can let it stand and the more thoroughl.
it is mixed the better the clay. When the articles are
made they are allowed to dry gradually in a warm
room when they are very thick, three months are
often allowed for this operation; they are then trans-
ferred to an oven and raised to redness. The more
slowly this drying and baking takes place the less the
liability to crack. In some cases fireclay crucibles
are not previously burnt or baked before use. In the
oase of pots used for casting steel it is found that if
the pots are burnt with the mouth downwards they do

from only semi-double flowers, and will forward "Saul Rymea" some if he will give me his address. It was saved from a few single that grew with some 225 une double ones as any one could wish to see having spikes of flowers from 9in. to 12in. long, be-ides a mass of side branches; they are what we in Sussex call the Giant stock.

NORMA.

WHALEBONE.-The blades [4273.]-SPLITTING previous to cutting are softened by boiling for a couple of hours in a long copper. They are then fastened edge upwards in an ordinary wooden bench vice, and planed by the subjoined tool. A B are two handles, CD is an iron plate, with a guide-notch E; F is a semicircular knife, screwed firmly at each end to the iron plate C D, having its cutting edge adjusted in a plane so much lower than the bottom of the notch E as the thickness

F

A

of the whalebone is intended to be; for different thicknesses the knife may be set by the screws at different levels. The workman holding the tool by the handles applies the notch E at the end of the whalebone blade furthest from him, and pulls it gently along so as to shave off a slice in the direction of the fibres, care being taken not to cut across any of them. These slips are afterwards dried, and planed level, and are polished with ground pumice, felt, and water. I do not know where "Enquirer" can obtain whalebone; but it is brought from Greenland in pieces containing ten or twelve blades. The blades are sometimes separated and cleaned by the sailors of the whaling ships. The price varies from £50 to £150 per ton.-H. U.

[4279.]-GAS METERS.-As a maker both of wet and dry meters, I, with all due deference to Mr. H. Newton, prefer the former for exactitude and durability. Not to extend unnecessarily my letter, I will quote Clegg's work, (no meau authority):-"The opinions of gas engineers continue to be divided as to the relative merits of dry and wet meters; but for accuracy of registration, when the water is at the proper level, the wet meter is not surpassed, if it be equaled, by any other."-E. WELLARD, Bordeaux.

[4314.]-RULE WANTED.-1lb. of cast iron contains 384 cubic inches; hence the cubic contents of any cast body in inches, divided by 381, will give its weight. Elucidation of example:-60 x 381 = 230-40 cubic inches in the block and 9 x 145 1305; hence the cubic contents 230-40-130-5= 1-76551+ inches thick. -W. DRISCOLL.

[4316.]-A DIFFCULT QUESTION.-I do not see that there can be any doubt about there being first the inside tube 12" diameter, gripped by a second tube, hoop, or ring, 18" diameter, and this second one gripped, in its turn by a third, with an eight ton grip.-UNIT.

[4322.]-SEWING MACHINES.-It is rather difficult to say exactly what the cause of "H. W.'s trouble is, as the effect he describes may be caused in one or two ways. There may not be sufficient tension on the top thread or the little brush is not properly adjusted against the hook.-UNIT.

[4856.]-SOFTENING SKINS.-If flowers of sulphur be mixed in a little milk, and after standing an hour or

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plate A A; it is of brass, carefully bored and polished. In constructing an air cane, be sure the reservoir is sufficiently stout, and made of copper, that the brass collar into which the breech screws fits accurately, and is well soldered. The butt end should be brassed up, not tinned. Further details if requested.-T. A.

[4072.] HARMONIUM QUERY.-As "Eleve" is doubtless too busy to answer queries just yet, I am sure he will pardon me for treading on his ground, especially as I shall merely tell Valve" what I have been told by "Eleve." The reed holes for 8ft. tone should be 14in. by 5-16in. at base; and 9-16in. by 3-16in. at treble. The pallet holes should be lin. by fin. at base, and in. by 3-16in. at treble, of course graduated as regards length all the way; and the pallet holes should be in. wide to all but the top octave-i.e., thirteen notes.-SAVI RYMEA.

[4076.]-NATURAL SELECTION.-This doctrine, which is gaining general acceptance among the leading minds, is that the many varied species of plants and animals are gradually developed from a few simpler forms by natural processes; that the surrounding conditions of good climate, &c., produce modifications and those are perpetuated which suit the varied conditions. The idea really is that nature does just what man does when he produces new varieties. How far the process is to be considered to extend is doubtful; some people are terribly afraid of the doctrine, under the idea that it does away with creative action; whereas, it really means that the creative power is everywhere present, always active now and for ever, instead of acting once for all. When fully developed and rightly understood, it will be found to teach as the Great Teacher taught, that the sparrow falls not to the ground unheeded by its Father and ours; that each springing seed, each blade of waving grass, and the humblest insect, whose life is but a summer day, is part of a great whole pervaded by the universal life, of which these different forms are the actions and development.-SIGMA.

[4002.]-THE ENGLISH CONCERTINA.-Since no one else replies to "Lost," allow me to say that the English concertina is really a good instrument. Its

not crack, but if with the mouth upwards, they do
The "grog "or burnt fireclay is added to form a sort of
skeleton, as it were, and thus prevent the tendency to
crack.-AN ASSOCIATE OF THE ROYAL SCHOOL OF MINES.

[4206.] CHROMATIC FAIRY FOUNTAIN. —
"Q. Q. R." evidently does not understand Prof. Tyndall's
experiment. When a ray of light, passing from water
into air, strikes the surface at an angle greater than
what is called the "limiting angle of refraction "-viz.,
about 43 27, it is totally reflected:", but this does
not occur when the angle of incidence is less. In the
falling stream the ray is continually reflected in this
manner along the stream, thus (see Fig. 1); but, in the

FIC.I.

FIG. 2.

个个

arrangement proposed by "Q. Q. R.," the ray would evi-
dently very soon strike the surface at a much less angle,
or, indeed, perpendicularly, and would accordingly pass
through into the air without reflection: the falling
water could not, therefore, be illumined.-IGNORANT
IRISHMAN.

[4226.]-DOUBLE STOCKS.-In my humble opinion
(although only an amateur) the best plan to get seed
for double stocks is to pick off from the single ones
every flower that has only four petals, saving only those
with five and six petals, on what a florist would call semi-
double, which will produce seed that will come nearly all
double. I have now got some seed nearly ripe, saved

two the milk (without disturbing the sulphur) berubbed into the skin it will keep it soft. Care should be taken not to prepare it too long before using, as the milk is apt to become putrefied. Perhaps the above mixture may not answer" Country Vet.'s" purpose, as it is used to soften the skin (human) and improve the complexion. Yet he can give it a trial if he chooses, as its cost will be very small.-KANSAS.

[4359.)-AMBER BEADS.-Amber beads may be repolished with whitening and water, or rottenstone and oil, finishing in either case with friction alone. Amber may be known from mellite (honey-stone) and copal, both of which are sometimes substituted for it, by the agreeable odour it emits when burning, and by the greater electrical power it possesses after friction; mellite is infusible by heat.-T. W. BOORD.

OF

THE

[4361.]-METHYLATED SPIRIT.-"T. L. H." is in error when he says turpentine is added to spirit, to form methylated spirit.-AN ASSOCIATE ROYAL SCHOOL OF MINES. [4361.]-METHYLATED SPIRIT.-This is a mixture of 90 parts of spirit of wine (S.G. 830), duty free, and 10 parts of wood spirit (methyl, alcohol, or carbinol). It cannot be used for medicinal purposes or beverages on account of its repulsive taste and odour; but for many of the purposes for which pure spirit of wine was formerly used, such as the preparation of varnishes, polishes, chemicals, the preservation of museum speciinens, &c., it forms an efficient and cheap substitute.BETA.

[4363.] -LIMEWASH ON MASONRY. "Agent" should use a weak mixture of spirits of salts, or muri

atic acid, and water.-BETA.

[4364.]-DRYING SMALL WHEELS.-A small room or cupboard heated by a gas stove would be the most economical, though I should imagine that any quick process would be apt to cause them to twist.-T. W. BOORD.

[4365.]-INDICATOR DIAGRAMS.-"Fireman." in order to calculate indicator diagrams, must divide them into at least ten equal parts by lines drawn at right

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