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what he might have vaguely guessed from the aspect of the crepuscular curve. "T. A." founds his views on the admitted difficulties involved in the problems presented by the sky and its varying lights. But these difficulties need not cause us to blind ourselves to clear evidence of another sort. As for "T. A.'s" explanation, I must say it is too wild for serious comment. If, indeed, he could show reasons for believing either-1st, that iron, magnesium, &c., can combine chemically with oxygen apart from the conditions which have hitherto been found necessary for such combination; or-2ndly, that these conditions exist in the upper regions of the air, he will doubtless be listened to gladly by scientific men-always supposing those reasons to be founded either on observation or on experiment.

I do not consider the ordinary employment of the photographer to involve "a series of very delicate investigations concerning the nature and properties of light," so far as the subject "T. A. has in hand is concerned. All photography can teach on that subject is that the light from such and such parts of the sky has at such and such times a greater or less active power. The conclusions to be drawn from this are by no means necessarily such as "T. A." imagines. R. A. PROCTOR.

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FAIRY WHEELS.

SIR, After having read the letter, p. 233, several times, I cannot discover of what kind of stone those discs are made. If they were not so great, I might have taken them for parts of fossil encrinites, but "Subscriber" says none of them were the same size or thickness; they must then have been made by man, cut, &c.; but for what purpose? Two suggestions present themselves. They were intended for throwing with thongs, or lassoes, or for stringing them as a necklace, or wearing as ornament. Very often pierced objects are found in caves, tumuli, &c. Might not these beads, &c., forming part of necklaces, have become, later, objects of exchange -8 primitive money? Might it not be possible to trace by that means the communication ancient tribes had one with another? The note of Subscriber "affords me the occasion of communicating this idea to my brother correspondents. I hope some other, more acquainted with the question, will bring also his stock of information. Meanwhile I quote a few examples, briefly, Mr. Editor, saying all notes should be drawn up as accurately as possible. Pierced objects have been found in many excavations in France, Belgium, &c., among what are called the remains of prehistoric times. A necklace of human teeth was found in Belgium; in North America, in the tumuli of Columbia River, Walla Walla, many beads, dentalium necklaces, &c., were found. One tumulus in Virginia gave 1700 grains or beads; with the Celtic warrior found in England, near Salisbury, were two fragments of fossil encrinite and a bead of pottery; a Celtic necklace, made of shells, was found near Dijon, in France; many Indians, negroes, &c., have their shell necklaces; remark among them the cowries-in many places at the same time a money and an ornament. The Egyptian beads, necklaces, &c., of so many different substances, are well known to all those who have visited the British Museum. The Chinese have yet pierced metal discs for their money; the English Hong-Kong coinage is another specimen of it. I have said a word, in another number, about the whampum of North America, also a necklace and a money.

BERNARDIN.

COLOUR BLINDNESS. SIR,-Concerning the remarks of "An Idipot," in your last impression, I have little to say. I have never met with a person to whom red appeared black, and I therefore thought it undesirable to dwell upon that particular form of the malady, though I know such an abnormal vision is repeatedly to be found described in books on the subject, though it is generally allowed that such an anomalous vision is only occasional, notwithstanding Sir David Brewster attempted to show that red colour blindness is most frequently to be met with, and that a normal eye loses its sensibility to red more readily than to any other colour, and that a defect in the vision of any person will be most strongly marked when examined by red light. Though "An Idipot" makes no mention of the fact, I should suppose that the combination of red with other colours does not produce the same sensation of colour that a normal eye perceives. For instance, in a purple the red is not missing, but it appears black, whence it is to be inferred that purple appears as a very dark blue. I would invite "An Idipot to make some further observations upon his anomalous vision, for it must be admitted that a colour-blind person is better ad apted to form a perfect conception of his defect than a normal-eyed person, and can more readily collect his facts; for let him (the colour-blind) be the inquirer, instead of the witness, and he may collect evidence about colours in every possible shape, from the scientific investigations of the philosopher to the artless remarks of the child. He need not go far for an answer to any question he may choose to put, however abstruse; and as to common facts, almost every one he meets is a competent witness from whom he may gather them.

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OMICRON.

EMIGRATION.-TO "F.R.G.S."

SIR,-I am glad to see "Cotton Clerk's" letter in the MECHANIC for this week. Let me also appeal to "F.R.G.S." Will he kindly tell me if there is any hope for me abroad, and where, and how? Although a clerk, I think I know a spade, a hoe, axe, prong, &c, when I see one. I am fast learning how many beans make 5, and can already see nearly as far through a stone wall as some people. I am a clerk 37 years of age, married, with 3 children, eldest 10, youngest 6 (both boys). We have saved a few pounds, and could realise a few more. For the last 3 years I have lived 4 miles from my work, I therefore know how to walk. I have

had 110 poles of garden allotment and orchard under
my hand alone besides my daily work and law work,
accounts, &c. of an evening, insomuch, that I have
often seen the sun rise before I went to bed. Pigs,
poultry, bees, &c., have also had my attention. I know
French and Latin thoroughly. I may, therefore, be
said to know what work is, both mental and physical.
It is not so much for my own as for the children's sake
I wish to go abroad. I should prefer the trade of
"earth tickling" to any other, being the only one I
know well. Will "F.R.G.S" either pat me on the
back or knock me down at once in the matter of
hope?
RAILWAY CLERK.

THE

THEREFROM.

"Germ

SIR-The great interest attached to the
Theory" in any of its relations is my excuse for asking
your insertion of this letter. It is an acknowledged
fact, that on elevated lands of high altitude, 7000ft.
ing immunity from may diseases, particularly from
to 8030ft. and upwards, the inhabitants enjoy a strik-
phthisis. It appears also to be the case that a sojourn
in such elevated rigions is a sure means of arresting
any further phthisical development which might have
had its origin at tower levels.

represented, I think, on p. 176, last number, is known in For more particulars sec "Die Forst Insectin." von Dr. many places, destroying the trees in the public walks. Ratzeburg. 3 vols., in 4to; " Entomologie Horticol"," by Alph. Dubois, Brussels, 1865, 1 vol., in 8vo, with fine plates; "The Farm Insects," by Curtis, &c., &c. BERNARDIN.

THE EARTH AND ITS FIGURE. SIR,-In discussing any matter with such gentlemen as Mr. Beardsley, it is necessary to adhere to one point persistently, and have it distinctly settled before passing on to another. Arguing for victory, and not with a sole aim at ascertaining the truth, such a writer acts very much like a small quantity of water con"GERM THEORY AND DEDUCTIONS tained in a bladder; grab it as forcibly as you will, it is sure to elude your grasp, and immediately shift its position to some other portion of the receptacle, and into a corn can only be fairly captured when it is driven up tightly Mr. Beardsley, like all men of his when he finds that an argument has been crushed by stamp, never recurs to a shattered argument, nor, it or acknowledge his failure. Thus, with reference a reductio ad absurdum, does he either try to rehabilitate to the explanation of the sun's setting by its getting beyond the focal distance of vision, whatever that means, he declines to answer the question as to how it, according to his crotchets, increases in distance. it is that the sun does not appear to decrease in size as Beardsley's last letter, and to state a fact which will I wish to ask an explanation of a passage in Mr. be something new to that learned astronomer. vessel "the upper masts" and sails are, according to I refer first to a vessel homeward-bound. In the approaching Mr. B., in focus. If so, how comes the hull to be out of focus, for it is as near as the sails (in fact nearer)? Again, how come the upper masts and sails to be believe our eyes," and that the bull and lower sails apparently growing out of the sea if the curvature of the ocean does not intercept the view? Are we "to are under water? Or lastly, are we to believe that the sails have left the hull behind?

These facts I have always thought most interesting,
and well worth of investigation, but although I have
continually been on the lookout for a solution of them,
I have never yet seen a logical, or even plausible
reason propounded. A considerable amount of inves-
tigation and attention to the subject-all the pros
and cons duly considered, but into which I need not
enter-has convinced me very strongly, or I may say
entirely, that the "germ theory" would be found to
account completely for the phenomena.

and consequently of their physiological, pathological,
Cold is a well-known arrester of germ development
and putrefactive effects, but I have never observed it
advanced that a rarefied atmosphere may be so also-
although of course from quite different reasons-
simply from the fact that air of great tenuity will not sus-
pend the germs mechanically and carry them about. If ex-
perimental research proves this hypothisis to be cor-
rect, I think it may be logically inferred that those
diseases which never appear amongst the inhabitants
of high altitudes, or are arrested in others upon going
to reside there, are really due to, and sustained by,
the presence of animalcular life. This is particularly
self-evident I think as regards phthisis, and suggests
the trial of a simple means for arresting and curing
that dreaded disease.

phere thoroughly before inhalation-much in the way
I propose it might be done either by filtering the atmos-
some of Professor Tyndall's experiments suggest-or
otherwise, first heating the animalcular air (to a degree
sufficient to destroy the vitality of the germs, and con-
sequently multiplying their morbid action) and then
cooling previous to using for respiratory purposes.

Taking for granted that the practical correctness
of my theory is demonstrated, let me by way of illus-
tration, suppose that such a building as the Palace
of Sydenham, for instance, were applied for utilising
it, when hundreds, nay, thousands of invalids could
live comfortably and pleasantly together for some
months, being all the time quite excluded from the-to
them-morbid atmosphere of the outer world, and
that thin air supply was treated, previous to intro-
duction into the building, in either of the ways I have
suggested. I think the same constitutional effects
would be found to be produced-and for similar
reasons-as already by a few months' residence at
high altitudes. A similar arrangement, and for a like
object, might be carried out in hospital practice.
Such experiments as would place the correctness
of my views beyond a doubt are entirely beyond my

power.

your readers is that, perhaps, in the event of their
This being so, my object in bringing the matter before
thinking my ideas worthy of investigation, some of
them will not only experiment themselves, and put
the matter amongst their scientific and medical
the theory to the test, but also, it may be, advocate
friends.

With your permission, Mr. Editor, I beg to ask for
columns of your widely-known journal.
a discussion and opinions of my proposal in the

JM-0.

BORING INSECTS, &c.
SIR,-The notice on "Boring Insects," p. 176 of our
ENGLISH MECHANIC induces me to forward a few
lines on the damage sometimes caused by insects. I
extracted them from several agricultural papers.

In 1832 the Hessian fly, Cecidomyia destructor, destroyed
corn in the State of Maine, Vermont, and in North
America, to a value of five millions of dollars.

Belgium a loss of 92 millions of francs to the wheat
In 1846 another small fly, Cecidomyia tritici, caused in
harvest.
were annihilated by the caterpillar of a phalana,
From 1740 to 49 nearly all the meadows in Sweden
Charcas graminis.

In 1786 the small turnip fly, Hallica nemorum, de-
vastated in Devonshire to the value of £100,000.
It is said that in 1784, the wheels of a mill on the
Severn were stopped by the abundance of cockchafers
in the water, what may be the truth of that assertion,
in our times, in 1866, in the Department of Seine
Infèrieure, France, the premium paid for the destruc-
tion of the larvæ or grubs of the cockchafers was
185 the Department of the Sarthe allowed a premium
18,000f., and the quantity gathered 160,000 kilog. In
of 30 centimes for an hectolitre, and 300 millions of
cockchafers or larvæ were collected. In 1807, 5150
millions were killed in Switzerland.

from 1665 to 1827 incalculable depredations in the
The Bostrychus typographus, or "printer," committed
forests of the Harz, in Germany, and caused the
stopping of the mine works, and nearly the total ruin
of some villages.
destroyed. There are actually more than 50,000 oak
In 1783 alone, 1,500,000 trees were
trees attacked by the scolytus in the Bois de Vin-
cennes. The common elm scolytus, Scolytus destructor

The fact I propose to state is relative to the passage. "The sailor knows by the chart the relative position of one country or island to another." Now that is just structed on the supposition of the earth being globuwhat, but for the invention of a distorted chart, coular, the sailor never could know from a plane chart. Mercator's chart is so constructed that, in order torted to an unlimited extent, so that a new scale of to preserve the relative bearing the distances are dislatitude, and even then it is only an approximation. measurement has to be be used for every degree of bearings all distorted and pointed wide of the true Had the true distances of the places been preserved on the plane surface, the sailor would have found the

mark.

Then, Sir, when Mr. Beardsley has made acquainted plain to us why it is that we cannot draw the surface with the Mercator chart in universal use, he will exof the earth on a plane without monstrously distorting either the bearings on the distances. I may have something further to say on the subject, but certainly not ED. E.M.] [It is better that this controversy should now cease. F. H. N.

before.

EXTRACTS FROM CORRESPONDENCE.

RUSHES. "Bernardin " says: "In reply to 'Camelford,' p. 207, I think he might do better to inquire at a paper mill in his neighbourhood, or to the Editor of the Paper Trade Review, 97, Newgate-street, London, as I am not able to give him the particulars he desires about price, &c. I believe rushes should be bulk possible." cut and dried, and packed, so as to present the less

TIONS.-"Vibrator" writes:-"I was rather surI. W. WOLFE'S "ORIGINAL" CONTRIBUprised on looking over a would-be rival to find my method of trisecting published in No. 264, p. 89 of the ENGLISH MECHANIC, copied and contributed without any acknowledgment by a Mr. Isaac W. Wolfe. If he wished it to appear in that paper he might at least have had the courtesy to acknowledge where he saw it, and not contribute it as the result of his own researches,"

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INDUCTION COIL.-ANSWER TO "SIGMA,”— "M. G. Cunningham" writes:-"Permit me to offer p. 207, I was quite aware of the theory be propounds, my best thanks to Sigma' for replying to my letter, but at the same time not quite satisfied about it, and think I will persevere with it. Experience has proved as my plan only involves a slightly increased bulk I that division of the coil by ebonite discs intensifies covered wire, which is expensive, and far more bulky the current, and the reason is theoretically explained as Sigma puts it. Why, however, if it be so, employ ployed with greater certainty than any silk covering Varnish, paper, tissue or other medium could be emthan plain, the only object being to insulate the layers? and working with four quart Bunsen elements, gives at a tenth of the price. My coil, now at its 12th layer, and I think it will answer well; should it not, howwell-defined improvement as each layer is finished, ever, I will not be so thinskinned as to keep my failure from those whom it may interest."

TESTED RECIPES.-" A. Boughey" writes:-" A Morayshire Man" is quite right in his remarks about ENGLISH MECHANIC for brillantine. The mixture the above. Some time ago a recipe was given in the cost more than what is sold in the shops, and turned out to be a very greasy mixture, with a-certainly not a perfume-which would effectually prevent any one from using it."

Preston "
THE "PHANTOM "
velocipede wheels to your readers as the best I have
BICYCLE. "Donald W.
says: "I can recommend the "Phantom
the advertisement.
have seen, and as fully answering their description in
J. Tydeman's unwarrautable
have them, and can say that his description of the
letter made me hesitate in ordering a pair; but now I

Spider' in the ENGLISH MECHANIC is quite inapplicable to the Phantom' wheel"

READINGS FROM THE GLOBES.-" Ab Initio" writes:-"J. Dyer, p. 235, in attempting to correct T. S. H.' appears to me to confound the words sun and time with each other. Philadelphia, for instance, has its time 5 hours earlier than London, it being only

7 a.m. there when it is noon here."

REPLIES TO QUERIES.

[2528]-MUSICAL BOX.-I must apologise to Harry Bertram for too severely criticising his description, which, however, I said was well repeated as far as the lesson was learnt. He means that the end of the roller has a flange which moves in the notch of right lever. This may be the case in very common boxes that only play two tunes, and I do not think would act for three; and it is bad, as it enables you to shift the barrel while playing, which has a bad effect, or even to shift the barrel when not playing, which is destruction to the box. In good boxes it is done by a wheel of the same number of teeth or rather spokes (and no rim) as the number of tunes to be played, which is fixed between the barrel and the first toothed wheel, only fixed eccentrically near the outside of that wheel, and every time it is carried round by the barrel turning, one of the spokes is caught by a fixed stud, and is held by it till the next spoke comes to the right place to be itself caught by the stud at the next revolution of the barrel. On the boss of this spoked wheel is a short piece of a screw or a camb which keeps pushing the barrel further and farther until the end of the camb is reached, when a spiral spring pushes the barrel back ready for the first tune again. The music is not stopped by the L-shaped lever dropping into the hole in the end of barrel, but when it does drop in, the curved arm shown in the drawing, p. 164, on the opposite side to the hook, catches hold of one fan of the fly and stops the works. It is a fan-fly not a fly-wheel, as it is not a wheel at all.-J. K. P.

[2639-OPINIONS WANTED. Thanks to Mr. Har

conical points, even in the best work. Cylindrical pivots are the easiest to make, and in foreign work a Swiss pivoting tool and burnishers are used. All English pivots are made with a polisher. I have seen a brass centre used, the pivot laying full length on it, but I prefer the point only supported. "J. A. E." uses the right word when he says 'catching" the centre. He must not file away all the broken pivot, but leave the mark where it was; he will find it much easier to catch the centre of that small ring than if he made the surface uniform. If he cannot mark the point exactly at once he must try to draw it afterwards to its proper place.NOBODY.

[3707.]-TWISTING POWER OF SHAFTS.-The relative strength of shafts to resist torsion is as the cubes of their diameters, the description of metal being the same. The relatioe strengths of different metals are as follows:Taking cast iron = 1, then wrought,, = 112 shear steel cast

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1

= 1.75 = 20;

1

and a shaft to be equal in strength to a cast-iron one, must less in diameter, shear steel be, if of wrought iron 25

1

cast steel.

8

9

Q. Q, R. [3714.]-BOILER." One in a Fix," may stop the humming noise made by his boiler by getting two sheet iron plates to fit each ash-pit. and having them drilled with a quantity of holes; the plates may be attached by hinges, or made to lift away when the ashes are got out; if he will try this I am confident it will cure his noise, having tested it frequently myself. Do not put too many holes in at first, but add them afterwards if the draught requires it.-J. B. CROSSLEY. [3786.]-AREA OF SAFETY VALVES.-The difference of the areas of the flat and concave valves may be found as

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rison for his advice about the links and the eccentric. When the lever is in the centre notch the valve spindle end is in precisely the centre of the link, and the eccentrics are properly set, but I think he is wrong when he says the link ought to vibrate on the centre without imparting any motion to either spindle or valve, for I have noticed several since, and they all work the valve a little, but not enough to open the ports, which is caused by the action of the two eccentrics one against the other. If our paper is an International Mutual Then Improvement Society I am surprised that the subject has not been taken up by more of its members.-JOHN W. BEDFORD. [2640] GIRDER PATTERNS.-In "N. L.'s" answer to my query he says that making the pattern bent would not do much good, as the moulder would ram it out of shape. Now suppose the girder to be 40ft. long, section as per sketch (Fig. 1), bottom flange 24in. thick, rib 1fin. thick, how will he ram down the ends, and if he can bend it to suit his requirements is it not just as possible to make the pattern bent, and so save time, and with more surety, for what is to prevent the ends from springing out again, as it would be moulded on its side? Again, a gutter of this section 28ft. long (Fig. 2), thickness at A Ain., and at bottom fin., which would be moulded on a block to At the inside, how would he bend that, and what weight would he require on the middle to keep it down, as it would be

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moulded with the bottom downhill. And again a foundation plate 33ft. section (Fig. 3) thickness of side A B C D fin., and the top 14in., moulded with the top or round side down hill; and lastly one of a smaller pattern, a tile plate bearer for malt kiln floors of the same size (Fig. 4) section, thickness at point of web fin., A at top Bin, and thickness of top flange in. and 4ft. 6in. long, which he might bend in the pattern with a bit of trouble and some weights to keep it there; but which would be safest, his plan or to make the pattern bent? And then he finishes by saying that it is a question whether one

FIG. 3.

ounce of practice is worth a pound of theory, but I think from the manner in which he writes he has not got an ounce of theory with a proportionate less part of practice on that subject. The above examples have all been cast, and the whole went straight except one of the foundations, and then the pattern had to be made a little more round. I hope this will be received, as sent, in a free open spirit.-JOHN W. BEDFORD.

[2675.-POLISHING PIVOTS.-The ridges mentioned by "C. R." are caused by the polisher having the side that

polishes the shoulder too much inclined to the side that polishes the pivot. It ought to be nearly at right angles. Pressing too hard against the shoulders has also a great deal to do with it. The polisher ought to have a side as well as a length motion given to it now and then, to cross the marks as it were. The bow takes long strokes, while the polisher moves very little; and always contrary to the direction the pivot turns. "Cylinder" will do well to attend to the above; and I may add, in answer to his query, the conical pivot he marks B is used only for good and best work, in holes furnished with endstones. Cylindrical pivots with the shoulder bevelled off are for more common work, though I have never seer but once or twice a Geneva cylinder with

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[3743]-SYPHON PIPES.-I think "Calculus" will find that the quantity of water discharged by a syphon will be equal (or thereabouts) to that discharged by a plain pipe of the same bore and length as the syphon, and with a head equal to the difference of level between surface of water in vessel or reservoir, and lowest end of syphon pipe. This ean be found by any of the ordinary rules for that purpose, and perhaps the following (I believe by Hawksley) is as good as

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The dimensions and quantities are here given as in feet, but will, of course, do just as well in inches, or any other unit of measurement.-Q. Q. R.

[3744.]-SILVER COIN.-I think there are errors in the legends; the nearest approach to it is a silver penny of James 1st, which reads on obv. "I.D.G. ROSA. SINE. SPINA." and on rev., "1VEATVR. VNITA. DEVS." If there is no mistake in J. Nash's description, the query must stand, but if otherwise, it had better be put right in your next.-D. T.

BATTY.

[3745.]-STEAM PIPE JOINTS.-I always use loz. of sal ammoniac to every llb. of borings, with just a dash of sulphur to quicken it in hardening.-ANTI-EGYPTIAN.

[3746.]-TESTING BOILER.-It will be of no use of Thos. Edwards testing his boiler without he can see the surface and seams of all his plates. If his boilers are only single rivetted, he cannot work them at more than 15lb. pressure. I had two boilers which I worked at 15lb. pressure. I had my boilers tested to 120lb., indicated by Bourdon's pressure gauge; they stood it better than they could be expected, although they (the engineers) will not allow them to be worked with more than 151b. pressure, being single rivetted

boilers.-ANTI-EGYPTIAN.

[3750.] SILVER COIN.-"A Beginner" will see his coin in Ruding's Appendix, plate 29, No. 12. It is thus described, p. 300:- Obv., BALDRED REX. Head rudely drawn, Rev.,+ETHEL..D MONETA. Double cross with an amulet in the centre. Bodlean Library." I imagine it to be at least scarce, if not very rare.-D. T. BATTY. [3751.]-ASCARIDES.-"A Great Sufferer" should take

half a glass of good port wine (not the cheap (!) advertised poison) every morning, fasting, for three mornings, then stop three mornings, after which repeat the dose. This will cure him in a month, provided he is careful in his diet, avoiding fruit, and especially cake or pudding with currants. Proved.

-F. H.

[8755.]-TURBINE WHEEL.-" Senex" seems to have asked me almost the same question as I have asked him, which was, what quantity of water and height of fall was necessary to drive an one-horse wheel. However, as near as I can get at it, the fall would be 20ft. through a pipe of in. internai diameter. I would also ask what height of fall or pressure of water is termed high pressure, as in some street mains ?-A. B.

[3757.]-A BOOKBINDER'S PLOUGH.-Enclosed is a sketch on the scale of of an inch to an inch, A A is the right hand cheek of the plough, 10in long by 4 high, 1 thick; the left hand cheek is of the same di

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part is 1in. in diameter, at the shoulder of the handle part it is 2in., a groove wide is turned in the plain part, which allows the bolt D to pass through, and act as a sort of garter pin, to cause the two cheeks to recede from or approach each other; the bolt Dis of iron square, and bevelled out to square at the bottom, so as to grip the knife F, which has a square hole, bevelled, to match the bolt. E is a nut, which screws down on a lozenge-shaped piece of iron, so as to grip the knife very tight. C C are two guide rods 13in. long, square, firmly fastened into the cheek A, the handle of the screw is 5in. long, as the knife cuts the handle should be gradually turned, so as to keep the knife to the work.-AB INITIO.

[3765.]-NAVAL ARCHITECTURE.-" G. E. J." should write to C. W. Merrifield, Esq., (Principal of the School of Naval Architecture,) South Kensington Museum, who will give him any information he may ask for as to the evening classes.

R. M.

[3768.J-POISONING BY CANTHARIDES.-I am very sorry to see "M. D." states in page 237, Vol. XI. that the effects of cantharides are only transient, &c. They are not so; in small doses it is an irritant of thebladder; in larger or improper doses it produces serious bleedings often resulting in death. It is administered surreptitiously under the idea that it is provocative of physical love, for which purpose it is absolutely useless. No mar conscious of his moral responsibility would ever administer it, excepting under and in strict accordance with the orders of a well qualified medical practitioner. I believe any person administering it for improper purposes is liable to a criminal prosecution.-E. DEACON.

[8772.]-OLD COINAGE.-Old copper coins may be sent to the Master of the Mint, Tower-hill, London, who will, no doubt, take them at, I believe, their full value.-R. M.

Block" will tell me whether he wants to make a portable [3773.]--PLATE PHOTO CAMERA.-If "Snatch camera, or one for the studio, I will tell him how I made mine. Of course, if the Editor, be agreeable, I could describe both. -plate is not too small to begin with.-MUS.

[3774.]-LOOSE PULLEYS, &c.-The best plan will be to

bore the pulleys about fin. larger than the shaft, and sweat a

brass bush in it, or one composed of the following alloy :(Babbitt's metal) tin 10 parts, copper 1, and antimony 1. I have proved the latter to be a very good wearing metal.STAEM.

turn the shaft end true, then bore out the loose pulley, and let the pulley work on a loose bush, bored and turned to fit the two, with a small collar and set pin at the outer end for fastening on the shaft; this would be a much better job than any composition, and is a very general thing nowadays; cast iron and cast iron would then work together, which is to be desired.-MUTUAL IMPROVEMENT.

[3774]-LOOSE PULLEYS, &c.-Wm. Corlett should

[3774.]-LOOSE PULLEYS, &c.-When worn in, the hole should be bored out sufficiently large enough to allow substance for the bush, which may be good gun metal, and will wear very well; the bush should be pressed in tight, that it may not move in the hole, and when it wears out, which will not be for a long time, if properly oiled it can be knocked out, and a new bush put in without doing anything to the hole in the pulley.-JONATH.

[3776.]-BOILER SAFETY-VALVE.-"One in Need," has not given quite enough information to enable me to answer his question exactly. Does the weight of valve and lever, as stated by him to be 74lb., give the true pressure exerted by them on the valve when in place? I expect not, and should imagine their effective pressure on the valve to be at least 21lb. Since the area of a 3-inch valve is 7 square inches, this will give 3lb. per square inch. So the weight will have to balance only 571b. per square inch, and will be found thus:

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It

glasses can be easily removed for cleaning, &c. A hot water tank in the bottom heated with a small gas jet underneath will make a tropical stove on a small scale, or a hot water, pipe round the inside, and a small copper boiler underneath will do even better. I have one, and for two years have grown with success the rarest tropical plants, orchids, &c. One year I had orchids only, the next I had caladiums, Egyptian papyrus plant, dwarf palms, tree ferns, &c. Now I have aquatic plants from the Amazons and Borneo, pitcher plants, &c. costs me little or nothing, as the plants always increase in value, and I have no difficulty in exchanging them. So far as treatment goes, he will learn more from the persons he buys his plants from than any one else, as each plant has peculiar habits. The case should have a reasonable amount of ventilation, so there is no need for care in fitting the glasses and woodwork closely; mine is open in. at every corner all the way up, and we burn a large quantity of gas in the room without the slightest effect on the most delicate plants; if

coal at 23s. per ton, for less than 2s. per week. At present we hare four cooking burners and cook for seven people never using the fire for any purpose, and I estimate the cost for cooking to be about 1s. per week; this, of course, includes boiling water for children's baths, washing floors, &c.-A DENTIST. [3793.]-COOKING BY GAS.-I beg to inform "J. M. D." that I cooked by gas for several years for a large school. The flavour of the meat, &c., were not only preserved, but the There should be a pipe on the top of the oven for the escape process was cleaner and cheaper than the usual mode. of the carbonic acid gas, &c., which should pass into a chimney or the open air,-J. DYER.

[3794.]-POLISHING STEEL.-"Cylinder" must be sure this clock is good metal, that his stuff is good, and that his steel was properly hardened before it was tempered, and not empered too much. He must have everything clean, and not dust flying about. The block must be refiled before each attempt, the least quantity of red stuff used, and the polishing they are quite close they get mouldy.-A DENTIST. moved very little during the process. Anything more is diff [3779.1-BOILER-" One in Need," should give the effec-cult to describe, as it is by the feel he will know when he has tive weight of his lever, and the weight of the valve; if he is rubbed enough. It all depends on leaving off at the right unacquainted with any method of finding the same, he may moment.-NOBODY. get it as follows:-Place the lever at the fulcrum on a three

sided file, and fix the short end, at the centre of motion, hang weight sufficient to balance the long end, thus the effective weight is the weight required to balance, and the weight of lever, to which he must add weight of valve.-JONATH.

MENT.

[8779.]-BOILER SAFETY VALVES.-According to "One in Need's" figures, the weight required on end of lever would be 671b. 10oz., but I am afraid the 71b. 14oz. weight of lever and valve does not include the effective weight of lever, in which case he is altogether wrong.-MUTUAL IMPROVE [3779.]-BOILER.-A weight of 58-184lb. placed on the end of the lever will give the required pressure. This weight is not exactly correct, but it is as correct as can be calculated from his description of the valve. If he requires the exact weight, he must give the weight of the valve and lever separately; if the lever be of the same breadth and thickness through out, its effective pressure can easily be calculated, but if tapered he must disconnect it, and try what weight will balance it, making the point in a line with the centre of the valve, the fulcrum.-THOMAS J. O'CONNOR. [3780.]-AREA OF SAFETY-VALVES.-The area of the valves for pressure is not at all affected by the difference of form shown in the two sketches. They are, however, not good forms of valve, as when the steam is blowing off strongly the current is considerably impeded by meeting the flat or concave surface of the valve before escaping. The form of valve ordinarily used on locomotive engines is, perhaps, the best of be simple valves, and is somewhat thus, the seating being a very small mitre, or sometimes a narrow flat ring of bearing surface.-Q. Q. R.

[3786.]-AREA OF SAFETY VALVES.-I think "Flat and Concave Valves" will find on a little consideration that there is no difference between the two, because if there seems to be more surface in the concave, the eolumn of steam is only 4in. dia. in the pipe's neek. Did he ever hear of the man who made a corrugated piston bottom, so as to work the steam on a greater area ?-MUTUAL IMPROVEMENT.

[3793.]-COOKING BY GAS.-If the gas is not under the meat inside the oven, the meat is quite as nice as that done before the fire. We find the best way is to put a Bunsen burner under an iron plate and cover this with a large tin cover, which is cased in flannel to prevent loss of heat. The meat must be supported on a stand in the centre of this, with the gravy tin under it. By this arrangement the meat is cooked as before the fire by hot air, and the most critical person cannot tell how it has been cooked. The same burners

may be used for boiling vegetables, &c., and plates may be warmed by setting them on edge round the oven, or putting them on the top. We have used this plan for 6 years exclusively, and as near as we can tell, it costs about 5d. or 6d. per week to cook for 3 people. During 6 months of the year we have no fires at all,a ndo king cannot be kept with

[3797.]-TELESCOPE STAND-If Mr. Turton will call at Brunswick House, Tanner's-hill, New-cross, he shall see the stand and mounting of my 9in. reflector.-J. DYER. [3798.]-TUBE FOR 9IN. REFLECTOR.-The thickness of the sheet iron of which the tube of my telescope is made, is rather over the 20th of an inch. The tube is 7ft. 5in. long, and the focal length of the speculum is 6ft. 6in.-J. DYER. [3799.]-BRASS COIN-Is a Nurnberg counter. As many of those legends have no meaning, and some of the devices fanciful, it is next to impossible to give further information about them than what has been given. A friend of mine laughingly said to me the other day, "I think the Nurnbergs have been pretty well worked or used up in the ENGLISH MECHANIC." I quite agreed with him, and I am pretty sure, Mr. Editor, that when you see one again you will be able to say in your Answers to Correspondents" what it is without giving us a woodcut.-D. T. BATTY, 9, Fennellstreet, Manchester.

[3801.]-LEVER ESCAPEMENT.-"Gracchus " asks for plain instructions to plant a lever escapement. This implies that all the pieces are ready made, and all he wants to know is how to plant or pitch them off into connection with one another. But as he adds, " proper dimensions," &c., he evidently wants to be shown how to make a suit of clothes to fit anybody, "proper dimensions," of course. I must remind him that a knowledge of the escapements is acquired studiously and with great application by all who wish to know anything of their business. The subject will bear no trifling with, and "Gracchus" must not think to get off less easily. I could do nothing to help him without an accurate plan of what he wants, or at least the half containing the escapement; and then if he knows nothing on the subject, all my explanations will be double Dutch to him.-NOBODY.

[3803.]-CHANGING COLOUR OF PRIMROSES.-I have about half a dozen differing in colour from vellow to a very dark purple. This change was caused by being yearly transplanted into richer soil. They first come an orange colour, then a light red, and eventually purple. The follow ing recipe will show "J, D. M." how to change other flowers:-The colours of flowers may be changed by certain additions to the soil in which they grow. Powdered charcoal deepens and intensifies. The flowers of the dahlia, rose, petunia, &c. Carbonate of soda reddens hyacinths; and superphosphate of soda alters in various ways the hue and bloom of other plants.-W. F. HAIGH.

[3810.]-CYLINDER PATTERN.-Let amateur make his cylinder model similar to sketch, the main feature of which is

CORE PRINT

CORE PRINT

the valve box and thoroughfare cores.

CORE PT

SECTION OF CORE BOX FOR VALVE CHEST

In the first place, put a good core print on valve box, then make a core box to suit the print, and inside this and from bottom side screw on three pieces of wood exactly where the ports want to be, and let them come through the top, and by making the core box for ports long enough to come through the valve box core, it all goes in together and prevents the moulder having to put studs in to carry the cores of the port. By putting a thick print on valve box it gets a good bearing surface for the cores.

-JOHN W. BEDFORD.

[3813.-POROUS CASTINGS.-This short query would admit of a very long answer; but I will try and make it as plain as I can. 1st. The sand is a very important thing; if it contains too much clay it is a great difficulty to make castings free from airholes. Clayey sand is only fit for light castings, where good impressions are of value, likewise avoid everything that will generate gas, such as coaldust, charcoal, and like substances. Ram your mould regular, and vent or pierce it with innumerable airholes; cast or pour it with as hot metal as you can get, not forgetting to run it in the mould as quick as it will go in. The sullage must be kept back with a skimmer during the pouring of the metal in the mould, and the head or git must be made so as it will be kept up or kept full during the casting operation.-N. L.

[3819.]-CHEAP GAS.-A great saving in the consumption of gas can be effected by regulating the pressure of gas on the burners. When more gas flows to the burners then they can properly combust, the illuminating power of the gas is deteriorated, and, of course, the gas bill is increased. One of the best ways to prevent this waste of gas, is to have a good regulator fixed near to the meter, which would regulate the flow of gas to all the burners. Another plan I have also adopted, that of placing a disc, with a small hole in the centre for the gas to pass through, in the elbow or brass socket in which the burner is screwed. The whole in the disc must be made according to the size of flame required at the burner. I have been able to save 25 to 30 per cent. in the consumption of gas by adopting the above. With regard to

the carburisation of gas by causing it to pass through a vessel filled with some hydrocarbon, this plan has been tried under two or three patents for the last 30 years, but nearly in all cases where it has been adopted, after a long trial it has been abaudoned on account of the difficulties, and the absence of the economy anticipated. A word respecting gas regulators, and regulating burners:-The best regulators for fixing near the meter that I know of (and I have tested several) are those regulating burner. Nearly all the regulating burners offered made by W. Tices, 65, Bartholomew-close, E.C., and by W. Sugg, Vincent-street. Westminster; Sugg has also a good to the public are worthless after they have been in use for a short time,-L. M.

Soldier plant. There is no plant so beautiful and interesting [3820.]-AQUATIC BOTANY.-Stratiodes Alviedes, or as this for the above purpose. Tie it to a stone and sink to the bottom; it will soon send up young plants on long stems reaching to the top of the water like so many juvenile palma trees. After a time the stems decay and the young plant floats free, of a lovely transparent green. They will soon out of doors, in full sunshine, where those not wanted should require thinning out; for this purpose a tank should be kept brown. Returned to the aquarium they will gradually go be placed, when they will get strong and change to a mahogany through all the intermediate shades till they regain their green hue, A constant interchange of tint may thus be kept up. The plant may be grown of any size, according to that of the vessel, and increase abundantly.-AMATEUR.

[3824.] GOVERNORS.-I can recommend Porter's patent governors as being very sensitive and powerful. They revolve very quickly-usually from 300 to 400 revolutions per minute-and when properly proportioned will not allow a variation of more than perhaps 3 per cent; so that a shaft running at 60 revolutions per minute would not vary more than 2 revolutions per minute. These governors are made by the Whitworth Company, in Manchester.-Q. Q. R.

the nitrate of silver stains, pour on solution of potassic iodide, [3827.]-NITRATE OF SILVER STAINS.-To remove then nitric acid twice diluted, and then wash with hyposulphite of soda. I have found this succeed in removing stains from the hands, but care is required.-OMIO. use:-A lute for the joints of iron vessels may be composed of [3829.]-SOLDERING.-Perhaps the following may be of 60 parts of finely sifted iron filings and 2 of sal ammoniac in fine powder, well mixed with 1 part of flowers of sulphur. This powder is made into a paste with water, and immediately applied; in a few seconds it becomes hot, swells, disengages ammonia and hydric sulphide, and soon sets as hard as the iron itself.-OMIO.

[3834.]-DUMB BELLS.-See "Physical Education." by A. Maclaren of the Gymnasium, Oxford. Clarendon Press Series, 5s.-OMIO.

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[3836.]-PITCH OF PROPELLER. The first thing T. J. O'C." must do is to bore out the eye of the propeller in the lathe, and fence np the outside end of the eye for the nut to bear properly that secures the propeller on the shaft; then take it out and lay it down on the ground with that side up that is faced for the nut, and level it up all the four ways of that part that is faced; then put a centre into the eye of the propeller, and from the centre of the eye draw a circle with any radius ou that part of the eye that is faced for the nut, and divide that circle into 12 equal parts, and also divide the blade from the centre of the eye to the point into feet, and draw the lines across the blade with a radius from the centre; then take a straight-edge that will reach from the point of the blade to over the centre, and lay the edge of the straight-edge on the point where one of the divisions cuts the and keeps it in that position by laying a block of iron on it; circumference of the circle and makes it run into the centre, then plume down from the edge of the straight-edge with a centre plummet to the divisions on the blade, and mark them with a centre punch; then measure the distance from the edge of the straight-edge to the plume point on the bladepresume that it is 6in.; then turn the straight-edge to the next divisions, still keep it running into the centre, and iikewise level, and plume down with the plummet again to the blade, and mark it, and then measure the distance down again from the edge of the straight-edge to the plume point-presume it is 20in. Now the difference between 20in. and 6in. is 14in.; then as every inch of the perpendicular distance gives 1-12th of the pitch in feet, therefore 14in. would be a 14ft. pitch to the blade of the propeller; and if the blade is not broad enough to take in a twelfth part, divide the circle into 24 parts and the blade into 6in., and every in. in the perpendicular distance, in the same way, will give a twentyfourth part of the pitch, and so on. The most convenient way to divide the blade is to divide the straight-edge into feet or half-feet, as it is required, and square lines across the edge; then make one of the lines coincide with the centre of the propeller, and the edge with one of the points on the circle, and then plume down from these points to the blade and mark them; then measure the distance down.-G. B. D. Flautist's" inquiries respecting the Boehm flute, I may [3845.] BOEHM FLUTE. - In answer to "Another state that the use of the rings is to stop holes which are beyond the reach of the fingers. On the old flute the holes are altered from their true position from the inability of the fingers to reach them; hence its notes are unequal in power, and are "out of tune." The latter defect is partially lessened by altering the size of the holes, but at the expense of adding to the former. Boehm overcame these difficulties by placing the holes in their natural places, and by making them of equal proportions throughout (the holes being made gradually smaller and smaller through a regular progression upwards), by which means he obtained uniformity of force and tune, and great increase of power in the whole scale of the instrument. But these advantages were met by a great drawback, for he found it necessary to alter the fingering of many notes; and this involved to those who already knew the old flute the unlearning of one system of fingering and the learning of a new. From this cause many, seeing the superiority of the Boehm flute, became dissatisfied with their old flutes; but finding the difficulties of the new fingering too much for their patience, gave up flute-playing entirely. Some few years ago Mr. Clinton, the celebrated flautist, invented a flute called the "equisonant flute," which not only had all the advantages of the Boehm flute, but retained the old fingering, and with increased beauty and brillancy of tone to the instrument itself. The writer of this has had practical experience of all these flutes, and much prefers his "equisonant" to any other. What I have said about flutes will equally apply to B clarionets. It would take too much space to describe flute machinery thoroughly.-H. T. LEFTWICH.

[If Mr. Leftwich desires to treat the subject more fully, space is at his disposal.-ED. E. M.]

of interest to "Another Flautist":"Nickel (Ni 29-57), a [3846.]-NICKEL.-The following extract may perhaps be

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metal of a greyish-white colour, with remarkable magnetic properties, which it loses on being heated to 660°. It is ductile and malleable. A Bavarian coin has been struck in this metal, and the impression of the die is said to be very perfect. The sp. gr. of nickel varies from 8:27 to 8:40 when fused, and after being hammered, from 8:69 to 90, it has a high melting point, and is but little acted on by dilute acids. Native nickel is found in the Erzgebirge in small quantities. Kupfernickel, or copper nickel is an arseniuret, and is also tolerably abundant. The nickel of commerce is obtained chiefly from kupfernickel, nickeliferous pyrites, and from the spiess obtained as a secondary product in the treatment of the nickeliferous ores of cobalt. As there has been a great demand for nickel in the manufacture of German silver, some improved methods of obtaining the metal have been introduced. They are, however, kept secret; but Mr. Phillips, in his Manual of Mineralogy suggests the following as the process likely to be followed:-"The roasted ore or spiess, after being dissolved either in sulphuric or hydrochloric acid, to which either nitric acid or nitrate of soda has been added to peroxidise the metals, is placed in large vessels, in which the insoluble matters are allowed to subside. The clear liquor, after it has cooled, and the copper and lead which have been precipitated by sulphuretted hydrogen, may be decanted off and treated by carbonate of lime in the form of common chalk, by which the iron and traces of cobalt will be precipitated, whilst the greater portion of the cobalt and the whole of the nickel will remain in solution. After the oxide of iron thus precipitated has subsided, and the liquor has been again syphoned off, the cobalt may be thrown down by saturating the solution with chlorine gas, by the addition of hypochlorite of lime, and then adding carbonate of lime. The liquor syphoned from this solution contains the whole of the nickel, which may now be precipitated by ebullition with hydrate of lime, and dried and reduced in the usual manner -HARRY G. NEWTON.

[3850.]-THERMOMETER.-"Thermo" had better place his thermometer against a piece of ice, which will have the effect of causing the mercury to recede towards the bulb; but if the bulb is not broken much, it will soon settle of itself. -SEMPER PARATUS.

8851. HARNESS.-"Equestrian " will find the best way to elean his harness is to well wash it in warm soap and water, (soapsuds would be better), dry it thoroughly, and then rub neat'sfoot oil on it; let it stand till next day, and if it absorbs the oil readily, give it another coat. This treatment is suitable for any kind of harness or leather; but if the bridle is a black one, he will find a great preservative in Harris's harness composition.-SEMPER PARATUS.

[3852. BRASS INSTRUMENTS.-They fill the tubes with melted resin, and twist them about when cold with apparently as much ease as they would use in bending a piece of cord. No doubt a sharp look out is kept for puckers, which they hammer in directly they appear on the inside of a bend of course with a small round-faced hammer. Copper tubes may be filled with lead, but it is dangerous with brass ones, as, to get the lead out, a good heat must be used, which makes brass brittle, and very likely to give way with the weight of the lead. I saw Distin's factory once, and was quite struck with the tube bending, which I had supposed such a delicate operation. I believe it is very difficult to get bruises out of tubes, and that they have a sort of jointed metal mould to put inside a bell which has a bent tube to it, and which has received any injury.-J. K. P.

[3852-BRASS INSTRUMENTS.-The bends of brass instruments are made by first filling them with lead, and then bending them; after that the lead is melted out. The reason they require filling with lead is to keep them from bulging out at the sides. The lead would, however, be inadmissible in the case of zinc tubes, as they would melt when the lead was run out. I am told resin would do instead, but this I have not tried. I should advise "Clutha" to try it, and report progress.-SEMPER PARATUS.

[3860.]-COPPER COIN.-Is of Catherine II., Empress of Russia; no value.-BERNARDIN.

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side to be bored out to make stuffing box, and a small boss opposite side to prevent spindle hole coming through, all bolted together with 3 bolts. These are prevented from turning by three flats filed on edge of moulding on casting as shown on plan, Fig. 3. The valve is cast with two tails for centering in the lathe, and a finishing cut taken with the slide rest to exact diameter of valve case. See Fig. 4. To get it out in case of wanting repair, slack nuts turn, and let a little steam on, then take out bolts, and all comes asunder. You need not cut off the tails from valve if they are not long enough to gain when valve is full open, which it would be by moving 300.-J. K. P.

3863.1-PASTILLES.Take 8drm. of cascarilla bark, 4drm. of gum benzoin, 2drm. of styrax, 2drm. of olibanum, 6oz. of charcoal, 14drm. of nitric, and a sufficient quantity of mucilage of tragacanth. Powder the substances and form into a thick paste with the mucilage, and divide into small cones; dry them until quite hard in a slow oven. -MINNEHAHA. [3863-PASTILLES.-" W. R. C." asks for some recipes for fumigating pastilles; I send the following, copied from a book which I believe can be relied on, but not proven on account of the difficuity of obtaining one or more of the components:-Pastiles á la rose. Essence of roses 1 part, nitre 9 parts, gum 12, tears of obanum 12, tears of storax 12, powder of roses 16, charc al 60; powder the solids very fine, and make a paste with gum tragacanth, 2 parts dissolved in rosewater 35.-Pastilles à la-Vanille: Gum galbanum 25 parts, tears of olibanum 25, tears of storax 25, nitre 25, cloves 25, vanilla 35, charcoal 115-make paste as above.-Orange Flower Pastilles: Neroli 1 part, nitre 9, galibanum 13, tears of olibanum 12, tears of storax 11, pare orange powder 12, charcoal 70, reduce to fine powder, and make paste with gum tragacanth 2, dissolved in orange-flower water 15, and rose water 17 parts.- Lastly, but hardly fit for a sick room, Explosive Pastilles: Make a hole at base of pastille and fill with gunpowder. I am afraid the queer names of these fragrant resins will almost frighten the querist; but I believe all except tears of storax and neroli can be bought in penny worths at the druggist's; if one shop does not keep them, try another. They say that tears of storax have not been in the English market for vears, but I believe the liquid storax will answer the purpose. By the word "tears" is meant the drops of resin in that shape, but of course the lumps will do as well. Orange and rose powder I take to mean powdered orange and rose flowers. Neroli is the essential oil of orange flowers. I will now give a simpler way for fumigating, but which has this objection, that everybody does not like the perfume. Dip brown paper till quite soaked in a strong solution of nitre; then, when perfectly dry, rub over it a varnish made by dissolving either or both gum olibanum (frankincense), and gum benzoin this soon dries and is ready for use; this last I have done myself, and succeeded in getting a strong fumigant-H W. BISHOP. [3871.]-THROTTLE VALVE.-I send for "Grocer's" benefit a full size drawing above of one I put to an engine of 4 cylinder. The same thing reduced to gas barrel which measures say inside and the casting bored to 1" would do for a 1 h.p. engine. The lower section of pipe is screwed and brazed into wrought iron flange and faced off in the lathe being a short length altogether, the upper flange cast iron apped for barrel, which is screwed, in with white lead. The intermediate piece is like a pulley with large hole through, and very deep growith a piece stuck in the pattern at oue

[3866 J-LATHE AND ITS USES.-For the information of G. Flackburn, the universal cutter spindle of which he speaks works or rotates in two internal hardened steel cones, the two ends of the spindle being external. The square bar which fits into the receptacle of slide rest of a 5-in. centre the Holtzapffel's standard is 9 1-6th square and 4 long. Perhaps I might add that I have arranged and now make a far superior instrument for simplicit, effectiveness, and durability than the one represented in Vol. V., p. 202, Fig. 256, and do hope before long to give the ENGLISH MECHANIC a representation and description of it.-EDWIN BAKER. [3867,]-LATHE DIVIDING PLATE.-If " R." requires a ready reckoner to assist in working the above, I shall be happy to make him a present of one for that purpose, if he will let me know his address.-EDWIN BAKER, 13 and 14, Mount-street, Grosvenor-square, W.

[3867]-LATHE DIVIDING PLATE-If you look at P. 12 of present volume, you will see a counting index figured and described in connection with the wheel cutting engine. It is not very troublesome to fit up, and need not be self acting.-J. K. P.

[3868.]-WATERPROOFING CLOTH.-Make a solution of india rubber in naphtha, and apply it to the cloth; this is the article used for waterproof coats; add a little linseed oil to it. If this is not suitable to "A. S. A." I can send a few other recipes. -SEMPER PARATUS.

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closer look at the group on page 63 of "F.R.A.S.'s" maps. He wants a sketch of the Pleiades; I refer him to his own on page 238 of present vol.-H. W. BISHOP.

[3876.]-TOOL FOR TURNING PIVOTS.-The latest tool for turning pivots is the French turnbench, with 8 centres and a small slide rest. They are from 10s. 6d. each and upwards.-S. TANENBERG, Leeds.

[3878.)-DAILY TEN O'CLOCK TIME SIGNAL.-Yes; all wires from 1min. to 10 o'clock to 1min. after 10 are in conection with Greenwich clock, when all working is suspended

for that time.-A TELEGRAPH CLERK.

[8879.]-GINGER BEER.-White sugar 10lb., lemon juice 9oz., honey lb., bruised ginger 11oz., water 9gal. Boil the ginger in legal. of water for half an hour, then add the sugar, juice, and honey, with the remainder of the water, and strain through a cloth. When cold add the white of one egg and oz. of essence of lemon; after standing 4 days bottle. Extracted.)-MINNEHAHA

[3897.1-NAPOLEON,-I beg to inform "H. B.", p. 231 that his coin of the French Republic, 1848, is not worth much more than its weight in gold. If it is, as I suppose, a 2 franc piece, its intrinsic value is 15s. 104d. in our money.HENRY W. HENFREY, M.N.S., &c., &c.

No

[3900.] ASPHALTE FOR ROOFING, &c. - I woul advise" Dublin Printer" to try the following; he will fin it useful in stopping many a crack besides those in his roof:Take 2 parts by weight of common pitch with 1 part of gutt percha, melt together in an iron pot; it forms a homeg eneou fluid much more manageable than gutta percha alone. to repair his gutters, carefully clean out of the cracks a earthy matters, slightly warm the edges with a plumber soldering iron, then pour the cement in a fluid state upon t cracks while hot, finishing np by going over the cement wi a moderately hot iron, so as to make a good connection and smooth joint. The above will repair zinc, lead, or in gutters, and is a good cement for aquariums.-PATIEN AND PERSEVERANCE.

[3869.]-WEIGHT OF WATER. -The reply to "Country-Special subjects:-1st B.A., Latin, Tacitus, "Annal [3907]-UNIVERSITY EXAMINATIONS.-London, 18 man's" query is very simple. By a rule in hydrostatics, any Book I.; Virgil, Eneid," Books VII. and VIII. Engli body immersed in water is pressed by the weight of a column of water the height of a perpendicular drawn from the centre History of English Literature during 17th Century; Bac of gravity of the body to the surface of the liquid, and in Mirabilis," and "Absalon and Achitophel; " French, Engli "Essays;" Shakespeare, "Julius Caesar; " Dryden," Anr breadth equal to the cross section of the body. A rnle to calculate the pressure on the bucket may be stated thus: for past and present. If "Xanthos" will write to me, I w every 7ft. of depth allow 3lb. pressure per square inch-give him any information he may require upon this subje A BOUGHEY.

[3869.]-WEIGHT OF WATER.-It is said that any heavy body 201b. in weight, taken to the top of a mountain 3 miles high, loses but oz. in weight; therefore the difference in weight of a bucket of water at the top and bottom of a well 90ft. deep, must be indeed slight. The apparent difference is, I think, due to the weight of the rope when the bucket is at the bottom.-HARRY G. NEWTON.

[3873.] BOOKBINDERS' GLUE.-Bookbinders use the same glue as carpenters and joiners, but break up the cakes into small pieces, and soak them in water for 8 or 10 hours, then thoroughly melt them in an iron or earthenware pot before using in the glue pot; some add treacle when using it for cloth work; some add paste. There is a work called Bibliopegia," I think it is by Arnott. I do not know the publisher, but if "Aristotle" will insert his queries in "our" MECHANIC, they will receive prompt attention from-AB INITIO.

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(3874] CONSTELLATION.-The group "Aristotle" sketched is the Pleiades, as he will at once perceive on a

C. H. W. B.

[3908.]-OLD COPPER COIN.-In answer to Mr. Na p. 239, the inscription on his coin is FAVSTINA AVGVST Faustina Empress). I cannot say without seeing the e whether it was struck by the elder Faustina, wife of Anto nus Pius, born A.D. 105, died A.D. 141, or by the youn Faustina, wife of Marcus Aurelius, died A.D. 175. The bro Coins of both are common, and worth very little.-HENRY HENFREY, M.N.S., &c.

CHINESE VACCINATION.-It may be news some that the Chinese commenced to practise v cination for the small-pox at Canton forty ye ago.

There are now public vaccinators at Pe with regular days and hours for scarifying inf brought to them, just as in London. When t supply of vaccine lymph falls short, it is rene from the English missionary hospital.

1

NOTES AND QUERIES.

[3910.]-CONICAL WINDING DRUMS. - Will some brother reader kindly give some particulars respecting the construction and working of conical or spiral drums, as applied at collieries for drawing coals, and state what conditions are to be observed in order to ensure their safe working ?-W. M., Junr.

[3911.]-GALVANIC CELL-I have a galvanic cell, composed of a stick of what I suppose to be carbon (it is black, about 5in. long, and lin. square) in a porous cylinder surrounded by a zinc cylinder about 3in. in diameter, all in a glass vessel. Will any of your readers kindly inform me what liquid or solution I should use to excite it; also the name of the combination, and whether it is best adapted for strength or constancy ?-HERMIT.

[3912] REVOLVING FRAME FOR SHOP WINDOWS. -I wish to construct a revolving frame to show pictures in a shop window, and find the ordinary meat-jack clumsy it revolves too rapidly at times, and requires winding up during the day; I should like also to avoid the return motion. Can any of your correspondents help me?-PITMAN. [3913.3-TO A. STRINGER-In No. 269 A. Stringer writes on velocipede construction; will he kindly, for my own and the information of others, insert a plan with the details of the three-wheeler he speaks of steered like a boat; will he also say where I can purchase an "English" velocipede?-CON

STANT SUBSCRIBER.

[3914]-WOOD ENGRAVING. I should feel greatly obliged if any brother subscriber can tell me where to obtain the best book of instruction in the above art, and the price? -K. T. Z.

[3915.]-NAIL BAGS.-I have a large quantity of nail bags which are worn out, for what purpose will they serve; will they do for making paper, or must I consign them to the rubbish heap?-W. CATTELL.

[3916.]-PAINTING BOILER.-How can I mix a good green paint to paint the boiler of an engine so as the heat may not effect it ?-A. W. [3917]-ICE CHEST. ICES.-Perhaps some of my fellow subscribers will tell me the best plan for making an ice chest (a few sketches would be a great assistance); also a few instructions for making ices?-BRIGHTON SUB.

brother

[3918.-ENAMEL.-Can any of my numerous readers inform me how to make white English glass, or the tin enamel, as made in France, that given a few weeks back was not white or good; also where I could obtain a brush for painting figures and letters on clock and timpiece dials?ANXIOUS INQUIRER.

[3919]-GALVANIC BAND.-TO "SUFFOLK AMAthe plan of "Suffolk Amateur," p. 11, last vol., I have tested TEUR."-I have very carefully made a galvanic band after it with a small galvanometer, but cannot get the slightest current from it. I have made it as follows:-A strip of copper and one of zinc, 18in. long, lin. broad, and 1-32th in. thick, are united at the ends by small copper rivets, I have lapped over these rivets with thread, and varnished over the thread with shellac in alchohol, the ends are left bare 1in., the copper and zinc are lapped spirally round with a piece of cotton list lin. broad, and covered in a bag of oil skin; I tried all strengths of vinegar, but to no purpose. Would "Suffolk Amateur" kindly say where I have failed?-W. A. [3929.J-MEASURING LIVE STOCK-Will some of your learned correspondents inform me if their is a book published on measuring live stoek, say an ox; or give a rule, through the medium of our MECHANIC, to measure a living fourfooted animal so as to find its weight?-A COUNTRYMAN.

[3921.] BRASS COIN.-I have a brass coin the size of a penny, on the obverse the bust of a man, on the reverse a female in chariot drawn by four elephants with LIE over them, there is an inscription round the bust, but the only letters I can make out are ALT-PAIANC. I should like to know of what coin it is, and of what value ?-TOM C. HOLLO

WAY.

[3922.-REMOVING PAINT.-Although some answers have appeared in reply to inquiries for a good alkali or such method for removing paint, still not one effectual mode has been suggested. If any brother reader could advice a ready and effectual method of softening the old paint on dorrs, &c., when it becomes thick and hard, so as to remove it speedily (without the use of charcoal fire), and enable the operator to clean off mouldings with credit, it would be a very useful enlightenment?-HOUSE PAINTER.

[3923.] GEOMETRICAL DRAWING. A method of drawing the ellipses that represent circles-N.B.-When the dimensions are not reduced to geometrical proportion; if one can also recommend a good cheap work on the above P-CARL

J. H. COTTHESSON.

[3924] SILENT FANS,-Can any of our readers tell me the diameter of the blade of one of Messrs. C. Schiele and Co.'s 50in. Excelsior silent fans, patented 1863 P-ONE WHO WANTS TO KNOW.

nia, as places suitable to make a home in, particularly as to peculiarities of climate, soil, productions, reptiles, insects, &c., if any insects to give much annoyance like the mosquitoes or gallinippers of the Southern States, U.S., which I have suffered considerably from, I reckon. I do not wish to go where it is very hot, but a little milder winter than our own, with its cold dull weather and piercing easterly winds. Perhaps our kind friend "F.R.G.S." would oblige.-TASMANIA.

[3930,]-WINES, JAMS, PICKLES AND PRESERVES.— Can any of your readers inform me if there is any practical work on making wines, and also a book on manufacturing jams and pickles. I have one, but it is of little use for a new beginner.-FRANCES BROWN.

[3981.)-INDIA RUBBER SOLUTION. Will any of your obliging correspondents, "Sigma," for instance, tell me of what the india rubber solution for mending waterproof clothing is composed, and the proportions of each material. Also whether there is any solvent for silk, which on evaporation leaves the thread without decomposition?-ALECIA BROWNING,

[3932.-BICYCLE RUBBER TIERS.-I intend fitting an india rubber tier to the driving wheel of my bicycle, could any brother subscriber kindly assist me in the fixing? I do not want to remove the iron tier; should also like a practical opinion of the merits of the rubber tiers, best shape, depth, &c.?-C. MORTIMER.

[3946.]-SYRUP OF HYPOPHOSPHITE.-If any medical correspondent will inform me of the medical uses and cost of syrup of hypophosphite of iron and quinine, together with the dose for ailments in which it is beneficial, I shall feel greatly obliged ?-G. THICK.

[3947.)-REMELTING HARD WHITE PAINT.How shall I remelt hard white paint, shelled off, composed probably of white lead bolled oil, and litharge.— T. S. U. [3948.]-INDIA-RUBBER TYRES.-If some correspondent, who has had experience with india-rubber tires, on velocipede wheels, would answer a few questions respecting them, they would oblige a aumber of readers who are interested in velocipedes Where they can be obtained, and price? The best way of fastening them on, and should they be used with iron tires? How long they last? How are they astened on the "Phantom" wheels ?-G. K. Guyana? A few particulars will oblige.-JOHN D. [3949.]-GUYANA.-Where is situated the Republic of

[3950.]-GOMUTUB FIBRE.-I find in a Dublin paper that the bristles imported for the purpose of making brooms for sweeping the streets, come from the Arenga or Gomuto palm. Is this not an error?-GoMUTO.

[3951]-BAMBOO NUTS.-I wish to know what kind of nuts are the "Bamboo nuts," I find mentioned in the cir[3933.]-HYPOPHOSPHITE OF IRON AND QUININE.cular of Messrs. Mandy, Horley and Co., last number of our Will any brother reader kindly inform me of the medicinal MECHANIC, and what is the use of those nuts?-GEORGES. properties, doses, and cost of the above preparation of iron [3952.]-LOAM PANS-Having some of these to make and quinine?-MAY. occasionally, and much annoyed with them veining inside, I shall feel obliged if any of our brother readers, having practical experience in moulding the same, will inform me the cause and remedy.-INQUIRER.

[3934.]-ORGAN ACCORDION STAND.-Will any fellow subscriber furnish me with a diagram for the construction of the above, so that it may be played with both hands-the feet, by means of a pedal, giving necessary action to the bellows?-SIGMATAU.

[3935. DISSOLVING SHEEP'S HORNS.-Could any of your numerous readers inform me how, or in what way, I could dissolve sheep's horns to make them into glue, size, &c., or for any manufacturing purposes ?-VERY OLD SUB[3936.-FAST COLOUR FOR SHEEPSKINS.-Will one of your readers kindly inform me how to dye the wool of sheepskins (fast colour) without injury to the pelts?W. C. S.

SCRIBER.

[3937.] CHEMICAL QUERY.-200grms of liquid nitrous oxide are gradually warmed to a temperature of 0°C., the barometer standing at 760mm. What volume will the gas occupy? Will E. G. Davis, "Urban," or some other friend kindly answer the above, and also show the way in which the answer is got?-ZETA.

[3938.]-AMERICAN CLOTH BAG.-Having to use in American cloth (being light and cheap) I find it answer when the course of my business a large light tight bag, made of the weather is warm, but when cold the enamel chips or peels off, and is soon useless, will any reader tell me how I can prevent this?-PETERBORO.

[3939.]-ELECTROTYPING.-Will any one please inform me how to take electrotype impressions in brass or in any other inexpensive metal harder than copper?-HERBERT. [3940]-THREE-WHEELED VELOCE.-I am making a three-wheeled veloce for two to ride, and to drive off the front wheel as in bicycles, and of hind axle with levers. I am at a loss to know how to make the hind wheels loose on the axle in turning a corner, as I am afraid if both fast on one axle it would be very bad to turn. Will any reader give an opinion on the following method, or suggest a better one? a if the back end of the nave, b is the axle, a section of, c is

a

a projection on that axle, d is a projection on the end of the nave, so that the projection on the axle will drive the wheel by it on going round a corner. I think d on the outside wheel would leave c on the axle going at the speed of the inside wheel. It is on the principle of a lathe driver.T. T. M.

[3941. MARKING INK.-Can any one tell me how best to use printers' type and press with marking ink, for marking [3925.] POSITION OF MAGNETIC POLE Can linen, clothes, &c. My difficulty is how to get the marking any of our readers inform me whether, as the de- ink on the type neither too much nor too little.-DAISY. clination of a needle is the angle made by the magnetic and [3942.]-MAKING BUTTER.-Will "Scorpio," or some geographical meridians of any place, and the magnetic meri- other reader be good enough to explain more fully the method dian passes through the magnetic poles, when the declination on p. 213. Does it not involve the digging of a pit, then be attended to. What materials are the sacks made of?OMIO.

[3953.]-COIL.-As I am afraid I have annoyed Mr. A. E. Tucker more than I ought, perhaps Sigma" would kindly answer me one or two queries. I quite forgot to state formerly that I intended making my coil in four sections. What would be the best way to connect them at the discs. I can almost fancy from "Sigma's" note in the last number of the MECHANIC that there is a possibility of doing without so much gutta percha paper, as I see recommended by everyone. I only hope he may show me how to begin, I'll be a willing pupil. I have taken Mr. Tucker's advice, and intend putting 81b. No. 36 wire instead of 4lb; will "Sigma" also say if I should get the new double mercury break instead of Mr. Ladd's spring core inbreak. I may state here that my old coil had a stead of in., as put in my note. (This is in reference to Mr. E. Tucker's reply to my last query, which I have to thank him for.)-D. FORBES. [3954.] SCREW AND WHEEL CUTTING LATHE-Would "J. K. P." or any of your numerous corwheel-cutting lathe made expressly for me, and I want it to respondents kindly give me their opinion on the following:I am going to have a 4in. back-geared self-acting screw and be as near to perfection as possible without being too complicated. 1. Would a 3ft. 6in. bed 4in. across be the size (please give all the other dimensions)? I should like it that length. 2. What size and rate should the screw be which goes inside the bed? it must be inside. 3. What size should the mandrel be, and what length; is a thread the right size to be as strong as necessary? 4. What size and number of teeth should the back gear wheels and pinions be? 5. The slide rest must have self-acting surfacing motion, what length should the bottom slide be, what length the top one, and what is the best form of tool holder for the slide rest: 6. What is the best wheel-cutting apparatus to fit in the slide rest to cut wheels up to 34in. in diameter? The most approved plan, I believe, for dividing the head is a tangent wheel fixed to the mandrel, and the screw which turns it to have a hand and dial; or is the rows of holes the best after all.-P. N. HASLUCK.

[3955.]-SCALE PARAFFIN.-Can any of your readers inform me how many tons of scale paraffin are produced in Scotland in one year?-S. P.

[3956.]-CHEMICAL.-Will Mr. G. E. Davis be so kind as to show how I could calculate the weight in grammes of 1 litre of methyl gas at 20°C. and 760mm. pressure; and also how to prepare acetic acid from the following: Cн ̧Ï‚ н ̧Ó, CaO, H2SO4, K2CгO1, Na2CO2?—R. TERSET,

[3957.]-POWERS OF NUMBERS.-Will Mr. Biggs, or some other contributor to our valuable paper, be kind enough to inform me how numbers are raised to their 36th and to their 17th powers. Take No. 10 for instance, to the 36th power = 3982. how is it done?-ECONOMY.

[3958.]-NAMES OF PARTS OF BELLOWS.-Would any maker of Reverte's bellows and hearths, be kind enough to give me the names, separately, of all parts of bellows, such as is used in a ship building yard ?-E. FoWLER

[3959.]-THE "EDINBURGH" VELOCIPEDE.-Will any brother subscriber give the address of the maker of the "Edinburgh" velocípede ?-C. T.

[3960.]-THE BLOOD.-I beg to ask through your valuable journal, if some kind reader would give me a recipe (cheap) for purifying the blood?-J. G. JACKSON.

[3961.]-BISULPHIDE OF CARBON PRISM.-Will any brother reader state what cement will resist the action of

bisulphide of carbon? I have made a prism, but the bisul

alters does the position of the magnet pole change with it ? filling and then re-digging? Has any condition of ground to Phide dissolves all the cements I have tried P-E. C. MURRAY.

VIBRATOR.

[3926.]-FORCING WATER-An engine forces water through a 9in. pipe, perpendicular, to a height of 30ft., will it require the same power to force it to the same height through a 9in. pipe, but such height being 180ft. away, with a gradual ascent of 1ft. in 6ft. ?-B. S. M. G. H.

[3927]-WINDOW PAINTING.-I shall be very grateful to any of your readers who will tell me of a rich transparent permanent crimson; also a pure bright yellow? Crimson Jake is such a varnishing colour it will not bear continued exposure to daylight, the colours are to be used with oil and varnish for glass painting. Amongst all the varied and valuable information contained in your journal, I have never noticed any on the old aet of window painting, I do not rican the modern process of staining, I have been a painter of dissolving views for years, but I should be most thankful if you could assist me in the former matter.-SABLE. [3928-RE-MANUFACTURING INDIA RUBBER-Will some reader kindly tell me if india rubber of first-class quality, in sheets of in. thick and under, could be re-manufactured, and what it would be worth per pound ?-J. T. [3929-EMIGRATION.-I should be pleased to get all the information I could respecting New Zealand and Tasma

[3943.]-BEES.-I have a hive of comb in which a swarm died last winter. Can any of your readers tell me is I may safely hive a coming swarm into it this summer, I may mention the hive is a common straw one with a wooden box under it quite full of comb, and is 3 years old. I feel doubtful in consequence of the comb being apparently dirty; it appears on the outside quite black, though I see no appear ance of mould. Would it do to remove any of the comb to make room for the new swarm, as it is quite full. Some hints on the general management of bees by a practical bee keeper might prove interesting to many of your readers, as they would to me.-S. W.

[3914.] ARITHMETICAL QUESTION-Will Mr. J. Sharp, who answered query No. 3710, p. 213, kindly show how it can be proved that a circle is equal to a parallelogram whose length is equal to half the circumference, and breadth equal to half the diameter. If he can prove it by geometry, will he kindly do so?-T. J. O. C.

[3945. PAINT FOR BOATS.-Would any reader inform me how to mix a bronze or copper-coloured paint for the bottom of a small model boat P-A MODEL BOAT MAKER.

[3962]-WHITE LEAD.-I bought some stuff for "white lead genuine," but find it has all dried up. like old putty, although at first it looked like ordinary white lead, and has been kept covered up in water; how is this?-H.

[3963.]-OAK, WALNUT, AND MAHOGANY STAINS. -Would some reader supply me with recipes for making oak, walnut, and mahogany stains?-ZEMBLA.

much obliged to "J. K. P." if he would give me a [3964) CAST IRON FOR TURNING.-I should be few hints about preparing cast iron for turning and former, I should like to know the shape of chisel, and If the filing, whether by chipping or pickling it. mode of using. If pickling be the better way, I wish to know the strength of acid, and time of duration of using it. I should also be much obliged by advice as to rebronzing a medal. It is one of a case of Napoleon medals, and the colour has been taken off by my attempting a cast in wax for electrotyping, leaving it a dull leaden colour. I should like to know how to get a cast from it for electrotyping, as wax sticks to the metal and breaks. Plaster of Paris makes a pretty good one, but I do not know how to make it conduct ing, as the plumbago will not adhere.-FABER.

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