(which becomes, when reduced to its simplest terms, but when the lever rises again from the faurang
x = 5y), [A]
and,

the larger ratchet wheel is held statiotan aut
The larger wheel is connected with s
wheels and pinions, by means of a pa
under-surface. The centre wheel carts &
hand, which points to figures on the disque.
[4693.)-BICHROMATE BATTERY-2
between the plates should be as little
in.; the copper wire can either be soldes
the carbon or a terminal soldered in to veng
clamped by means of the screw.
done carefully to ensure a good ens. 3.
solder, using plenty of soldering flaid:
good deep hole into the carbon and.

B. E. Loddy means by the first portion a. r, is
it a misprint? The sizes of foreign = re
reckoned by lines and English watches m. g
thus:-8, 10, 12, up to 24, which is the b
general use; No. 8 size is the smallest.—I
scrub them, and then lay them in dissltel
[4701.]-CLEANING COINS.—To clean 06 FTL
copper (a super-saturated solution), for
then brighten with a brush or leather.
be cleaned in the same manner, by an
silver.-C. B.

[4652.]-TONING BATH.-Dissolve 25 to 30 grains of crystallized phosphate of soda in 6oz. distilled water; then stir in 1 drachm of distilled water containing 1 grain of chloride of gold. Immerse the prints, which after the Eastern islands. 1247 is the Mohammedan date. quired speed by the driven wheels for dinded, the

SEPT. 16, 1870.J

affinity of sodium for chlorine is greater than that of zinc; let us express this by figures, which are, it must be understood, purely arbitrary, and used simply to convey the idea. Expressing the attraction of zinc by 40 and that of sodium by 60, we see that the zine cannot break up a molecule of the salt; but, formulating it, Na Clax Zn, we readily conceive that the internal to "H.affinities of the sult are weakened, that the molecule is

J. G." would get "Bee-keeping for the Many," pub-
shed at the office of the Cottage Gardener, he will find
Il the information necessary to an amateur. I forgot
mention that a piece of perforated zinc should be
laced over the hole in the hive to prevent the bees
rom coming out when the bottle is taken off to be re-
illed.-OXFORD.
[4720.]

KALEIDOSCOPE. In answer

K. L." (page 575), I have to state that this pretty opical toy is made thus:-Procure two oblong slips of ooking-glass, length and breadth at pleasure. Join hem together at an angle of 60; the upper side of the riangle is covered with stiff cardboard blackened; the whole is then tied up neatly and put into a tube of tin or brass of corresponding size; one end of this tube is covered with a disc of glass and the other end with a diaphragm, with a small hole in its centre, through which to look at the coloured objects contained in the cell at the other end. This cell is fitted on the tube like the object-glass of a telescope, and made to turn round; it has a disc of ground glass in front; this cell contains the pieces of coloured glass and other objects which are required. Then keep the proper side up and the body of the instrument stationary, and turn round the cell on the end, when the effect will be very striking, in consequence of the endless variety which can be produced. An angle of 60 gives six reflections; one of 90 gives four ditto; one of 45 gives eight; but 60 gives the best results as to brilliancy.-VALVE.

[4723.]-BAROMETER.-In reply to "Geometros," question 1, The degrees on my barometer have nothing to do with the thermometer, and are merely divisions for the reading off of the liquid level; 2, the heat of course affects the height of the liquid, as I have fully explained in recent numbers which I hardly think "Geometros" has seen; 3, as the liquid never stands at the same place for any particular degree of temperature (the level being varied by barometric pressure) it would be quite useless to place the temperature graduations on the tube. Hence the necessity of the index which secures the proper corrections.-CORNUBIA.

[4725.]-SHORT SIGHT.-"Moses" does not state what his daily occupation is, therefore my reply is not 80 comprehensive as it might be, but I recommend him to wear concave spectacles when out of doors, he need not fear any injurious results, I have done so for many vears without experiencing any detriment to my eyesight.-AB INITIO.

"Moses," I [4725.]-SHORT SIGHT.-In reply to should certainly advise him to use glasses, for instead of straining his eyes, they would relieve them; he need only wear them when out, because they would cause confusion in near objects that he could before see well. It is very strange that his eyes should get more convex as they appear to have done from his communication, but he may rest assured that his eyes will improve as he gets older.-B. T. N.

[4725.]-SHORT SIGHT.-The case of "Moses " is a very common one indeed. If there is no organic disease of the eye he is probably suffering from conical cornea, the cornea becoming too convex. This is caused by close application to minute things, as reading, writing, watchmaking, tailoring, the microscope, &c., when the eye is in a weak state. To prevent the eye getting worse cause. (it will probably never get better), reinove the Take to a seafaring or farming life. At all events examine minute things as little as possible, and then not by candlelight, tirelight, or twilight. Strengthen the eye by frequent washings of pure cold water. He may use spectacles with advantage, only the spectacles should suit him. They should be opposite the eyes, the distance between the pupils of his eyes being the same as that between the centres of the glasses. If there is no organic defect, he could easily find a pair of concave spectacles, with which he could see distant objects quite distinctly. He should reject those and take a lower power, one which leaves a certain amount of haziness about the letters on the opposite side of the street. The reason being because the eye tries to accommodate itself to circumstances, and if the spectacles be rather too weak the eye will never feel tired, but in trying to accommodate itself to the spectacles it is at the same time lessening the convexity of the cornea. If the spectacles be too strong the ee becomes more shortsighted in straining itself to sui them. Above all never use an eyeglass, or he will cont nually have to change it for others of a higher power. Through an illness my eyes became weak at fourteen. Reading caused me to gradually shortsigh ed. I can now read distinctly at no more than 7in. Igive" Moses" the benefit of 25 years' bought experience in this matter.-G. P.

become

held together by a residuary, force of 20 only, and is
thus " polarized;" it only requires, therefore, some other
force to complete the rupture. In the manganese battery
this is supplied by the readiness of the extra atom of
oxygen to enter into a new combination, and as a result
of the several actions which take place on the line of
I think Mr. Jarmau is
and chloride of zinc formed.
polarized molecules, the sodium is transferred elsewhere

mistaken as to the iron. I have seen cast-iron long
buried pass into such a state as to become soft and have
great excess of carbon, but ordinary cast-iron contains
only from 3 to 6 per cent. of carbon, either as graphite or
combined.-SIGMA.

[4729.]-a ARIETIS.-I do not think a Arietis can be
seen with a 3in., unless the observer possesses altogether
If I remember rightly I
exceptional powers of vision.
describe it in my "Half Hours with the Telescope," as a
very difficult object for such a telescope. A sharp-eyed
friend had seen it with such an aperture, or told me so;
and it is to be remembered that seeing minute points of
light depends quite as much on eyesight as on the
telescope. If I did not believe this I should have to
regard some esteemed friends as untruthful, for they see
objects which are not only wholly invisible to me with the
same telescope, but commonly regarded as wholly beyond
the power of such telescopes. The position angle of
a Arietis is about 107°, B of about 10th magnitude and
purple, distance is considerable, and B is triple.
RICHARD A. PROCTOR.

[4731.)-CARBONS.-The process given by me for
protecting carbons and their connections does not at all
affect the conductivities, I carefully tried that point be-
fore publishing the process; of course it will destroy
conductivity at the surface, that is to say, the reception
of the current; though if well rubbed so as to clear off any
film of paraffine current will pass into it from metals to
considerable degree, but of course not from liquids, be-
cause they do not come into real contact with the car-
bon.-SIGMA.

[4782.]-GAS TAR.-I am not acquainted with the
process, and should think a preparation of carbolic acid
likely to be more useful and much pleasanter.-SIGMA.
[4733.]-BRONCHITIS.-"Omega" is surely mistaken
"bronchitis."
when he describes his symptoms as
Bronchitis is an acute inflamination of the membranes
of the bronchise, or breathing-tubes, and if attacked
with it he would not be able to walk about long.
"Omega's " ailment is evidently chronic, and the fact of
the mucus being streaked with blood is an extra reason
why he should seek medical advice at once.-SAUL
RYMEA.

[4738.]-GEOLOGICAL.-The question of "Veritas
is one I believe most unaccountably shelved by our pre-
The only theory I have seen ever
sent geologists.
attempting it was by a Fellow of the Dublin Society;
that in the frequent and tremendous dislocatory earth-
quakes attested by the "faults" or dykes of those early
strata, each of those dislocations or cracks through the
whole earth crust, down to the very lava level, acted as
a mill, grinding and shooting forth upward clouds of its
own pulverised rock, which, diffused through a vast ex-
tent of overlying sea, then settled on its bed, forming
what has, under intense pressure, for thousands of
ages, accompanied in many cases by baking] heat, now
become a thin bed of sandstone, shale, or clay. Phe-
nomena feebly representing this are known even in
some modern earthquakes, as the last great Peruvian
Now the ex-
one, a dark and stifling cloud of dust being suddenly
puffed up from a new crack into the air.
tent of rub or "downthrow" in these dislocations is
Say it is inches-what
rarely perceptible or noticed.
then must have been ground and shot forth by the ninety
fathom fault, the Cleveland, or any of the innumerable
great faults that dislocate our elder strata in all direc-
tions, when the miles of crust thickness were thus
wrenched through in the throes of the earth's infancy.
If coal beds be now preparing about the great tropical
river mouths, that pour down a yearly tribute of forest
spoils, there must be very thick uniform deposits, as
much so as the Nile alluvium, the London clay or chalk.
The old strata, with their countless distinct beds, rarely
yielding a stone a yard thick, and continual changes of
material-a foot of this, two of that, so many
deep red sandstone, one inch pale buff, and then the
deep red again-these indicate a widely different state of
nature from any now known; and I agree with that
Irish geologist that it is utterly inconceivable the bulk
of those ever changing sediments were ever derived,
like the tertiary or alluvium, from the rain and river
wash on ancient lands, as it is now the English fashion

to assume.-E. L. G.

inches

[4725.]-ANSWER TO "MOSES."-My case was exactly like that of "Moses." About the age of 14, my sight got so short that I could see nothing at any distance. I was consequently debarred from every amusement or occupation requiring eyesight. About this time a friend made me a present of a pair of glasses, certainly the most valuable present I have ever received. It as it were opened a new world, or rather re[4740.]-CONTACT BREAKER.-I believe the constored the old one to me again. I, who had been getting was suddenly tact breaker of the Polytechnic coil is a modification of gradually blind, so to speak, for years Foucault's. I am now 34, and A stout glass vessel is perforated at the made to see again as well as ever. bottom, and a large platinum wire inserted, a layer of an have used the same glasses ever since without the slightest inconvenience of any sort. My eyes are certainly no amalgam of platinumn is placed in the vessel and covered worse, though I cannot say they are much better, than for several inches deep with the strongest alcohol. On they were when I began to wear them. I cannot now (nor the top of the vessel is a fitting exactly like the rod of could I then) read print as large as the heading ENGLISH the bichromate cell (in fact, the apparatus is made from MECHANIC at more than lift. distance without my speca bichromate battery), with a spiral spring added to sustain the rod, the extremity of which is armed with a tacles, but with them I can read the smallest print in the above (such as the address, &c.,of the publisher at the large platinum knob. To make contact, the rod is debottom of last page) at more than arm's length from the pressed till the knob touches the amalgam; to break eye. Of course I have a pair of very strong lenses, but contact it is simply released and the spring withdraws the rod, which is, of course, prolonged with ebonite, &c. Moses" need have no fear of the term "very strong I am not quite sure as it only refers to the diverging power of the lens, and to prevent danger to the operator. as far as my experience goes has no injurious effect that this is the final forin the contact breaker has asupon the eye whatever. My glasses were the best peb- sumed, as a good deal of trouble was experienced at first. bles (this I believe is an important thing to notice), and SIGMA. cost originally half a guinea (steel frame) at an optician's in the Strand. Except a new pair of frames I have had no other expense with them, though I have worn them continually out of doors and ever since without an hour intermission, except at night time. If my experience is of any use to " Moses," he is heartily welcome to it.-IVORY.

แ

[4728.]-ZINC AND SODIUM CHLORIDE.-Mr. Jarman overlooks the altered conditions in the two cases. Zinc cannot displace the sodium from common salt, for the reverse action takes place; in the old phrase the

[4744.] — GUN-COTTON.-"Experimentalist" does not state whether it is the explosive or soluble guncotton he wishes to obtain, but I presume it is the former, from his adding no water to his acids; if so, the nitric acid used ought to be of the specific gravity 1-500, this is poured into a vessel and mixed with twice its volume of strong sulphuric acid; then the cotton is immersed in it, and the air bubbles well squeezed out with a glass rod; after it has remained in the acids for about five minutes it is removed and instantly plunged into water; after being washed until it loses all traces of

acid, it is dried and the matted parts pulled out with the fingers or a pin.-P. B.

(4744] GUN COTTON. - Take of cotton 1oz.,
sulphuric acid, 5 fl. oz., nitric acid, 5 fl. oz.; mix the
acids in a porcelain mortar, immerse the cotton in
the mixture, and stir it for three minutes with a
Transfer the
glass rod, until thoroughly wetted.
cotton to a vessel of water, stir well with a glass rod,

decant the liquid, pour more water on the mass, and
repeat the process until the washing ceases to give
a precipitate with chloride of barium.
product on filtering paper and dry in a water bath.-

W. F. L.

Drain the

[4744.]-GUN COTTON.-Mix 4oz. of pure, dry, nitrate of potash with 30 fluid drachms of sulphuric acid (sp. gr. 1845), and stir into this mixture carefully

120 grs. of best carded cotton. As soon as saturation is used), throw the cotton into a large pan of clean rain water, and change the water repeatedly until litmus complete (in about one minute, if proper care has been ceases to show the presence of acid, then squeeze it in a cloth and, after being well pulled out, dry it at a temperature of about 180°. (Ure.) I have not had occasion to make gun cotton for some years, but I am pretty certain that I have tried the above, among many others, acid is sometimes used in place of nitrate of potash, and found it suitable for photographic purposes. Nitric though I think the latter is preferable.-T. W. BOORD.

[4744.]-GUN COTTON.-One part of finely, carded cotton is immersed in 15 parts of a mixture of equal measures of nitric acid, of specific gravity 1.52, and The cotton sulphuric acid of specific gravity 1.845. must be completely immersed in the mixture, otherwise it becomes so hot as to undergo instant decomposition. a large volume of cold water, and then washed so long as the least trace of acid is perceived, when the moist After a few minutes immersion it must be plunged into mass is placed upon litmus paper. It is then to be careprepared for military purposes it is found advisable to fully dried at a temperature below 212° Fahr. When prolong the immersion in acid for forty-eight hours, and to continue the washing for several days. thus prepared gun cotton scarcely differs from unchanged cotton in appearance; it is white and fibrous, and rather harsh to the touch.-OXONIENSIS. [4752.]-DIFFERENTIAL CALCULUS.- By formula $ (x) √(x)

or =

if u

'(x) (x) '(x) (x)

du
dx

d.
1.4(x)
d x

1 ↓ (x) } *

As

[4764.]-BRONZING COPPER URNS.-The surface, thoroughly clean and bright, is covered with a thick coat of rouge and water; when dry, the article is placed in a short time until the rouge has turned to the desired a clear hollow fire (say a chamber of bricks, red hot) for shade of colour. When the article is placed on a suitable stand, and polished with a soft brush and rouge powder and afterwards with soft leather. The tinning and soldering are subsequent operations.-G. F. B.

[4768.]-POLISHING PLASTER OF PARIS.-First make very smooth and free from grit with glass-paper or otherwise; when perfectly dry, oil with linseed oil, or anything similar, and required to be white, maké when hard, French polish in the usual way. If a bust; smooth size with white size, and varnish with white hard varnish.-DERFLA.

[1778.]-MOTION OF THE EARTH.-The "Querist " should read Lardner's "Mechanics," from which the following is extracted: "A body once put in motion would continue for ever to move in the same direction, and with the same speed, unless stopped by some external

Both are 5in. centre lathes. As far as my experience goes I think Holtzapffel's mandrel screw is the best for amateur purposes, its length is barely 11-16in. I am afraid "J. K. P." would favour us with a word on the subject these particulars are but of little use alone, perhaps of mandrel screws.-T. W. BOORD.

[4776.]-LATHE.-The thread of mandrel-nose that I have generally seen on Holtzapffel's 5" ornamental lathes 25 For the same-sized lathe is 9-45 to an inch; deep thread, angle of point of screwtool 45°, and diameter

32 Evans uses the same thread or else 9 to an inch. A inch. My new double-geared 5" is Whitworth's, 1" Sin. lathe may have Whitworth's thread 11 to an diameter, 8 to an inch, and a 54in. double-geared, made last year, was 14 diameter, 7 threads to lin. Whitworth's threads are with a point-angle of screw-tool of 55 throughout. As to the pulleys, I always put in the small lathes, be about 1 in. less than the largest possible biggest pulley the headstock will take in, which will, for face-chuck, and for 5in. to 6in. lathes (say) in. less of the base part of the headstock. The outside row of than the chuck, as you have to allow for the thickness divisions need not be more than 3-16in. from the edge (the larger the better), and 5-32in. between the rows

centre to centre, is sufficient for amateurs' lathes, and affords room for strong holes-i.e., that will take a strong peg. And the holes should be drilled with a taper drill and have a peg that fits accurately. I have not yet schemed my model division peg or "alidade," but shall shortly, and communicate the same. Those in common use are abominable.-J. K. P.

[4779.] HOLTZ' ELECTRICAL MACHINE." A Revenue Officer " (p. 599) will find the Holtz machine explained with detailed wood-cuts, in the ENGLISH MECHANIC, Vol. III., p. 170. In French, description with wood-cuts is to be found in Les Mondes (L'Abbe Moigno's), Vol. XV., p. 499, also in Ganot's "Physique," the last edition, the 18th. Poggendorf's improvement of asing a "full" fired disc with small holes, is mentioned in Les Mondes, Vol. XXII, p. 301. The latest change proposed by Fr. Provenzali, of the Roman College, was announced and explained in a Roman journal of last May.-E. KERNAN.

[4779.]-HOLTZ'S ELECTRICAL MACHINE.-A description is given in No. 226, Vol. IX., p. 391. Several modifications have been made lately, and several essays and papers on the subject published in Germany, but I am not acquainted with the particulars.-SIGMA. [4779.]-HOLTZ'S ELECTRICAL MACHINE.-In reply to " A Revenue Officer," he will find a description of Holtz's electrical machine in Ganot's" Physics," page 616, edited by Atkinson, published by Longman. Also in Brooke's "Physics," page 390, published by Churchill. -B. T. N.

[4781.]-SUSTAINING BATTERY.-I do not know what is the special battery referred to; from the description it may be the sulphate of mercury, as in this mercury does collect; but an ordinary Daniell's or a sulphate of lead battery would do if considerable force of current is needed; or a manganese or mercury cell, if merely signal instruments are to be worked. The period of working would, in any case, depend on the amount of work to be done in any given time; it is quite impossible to name any time without knowing this.-SIGMA.

Our

[4785.] - BINDERS' TOOLS. I cannot inform "L. J. W." where he can obtain a pattern book. Has he applied to Timbury, 104, Fetter-lane, E.C.? I have never given any recipes for staining leather in " MECHANIC, but if he will state in the next number whether it is white calf he wishes to colour, and the particulars, I shall be most happy to give him the desired information.-AB INITIO.

[4786.]-IMPRESSION OF FERN LEAF.-Well oil a piece of paper (say note paper) with linseed oil, hold it over a smoky flame, such as that given by a tallow-candle with a long snuff, moving it about so as to evenly black it all over, place it on a smooth surface and lay the fern leaf on it; over that place a common piece of paper, rub the hand well over the part where the leaf is, remove the paper and place the leaf, the blacked side downwards, on the paper to receive the impression; place over this another piece of paper, rub the hand as before and on removing the paper and fern an accurate impression will be found upon the paper.-P. B.

[4786.]-IMPRESSION OF FERN LEAF.-I have found the following way answer very well. Take a sheet of note or other paper, grease it on one side and then hold it over a lighted candle, so that the smoke blackens the greased paper, when well blacked place the leaf on it, press it well and then transfer to a clean sheet of paper, after pressing it some time it will be found to leave a very good impression.-FRANCESA.

[4786.]—IMPRESSION OF FERN LEAF.-Roll the leaf carefully with a printers' ink roller, lay on a sheet of paper and apply pressure in a screw pre-s.-T. W. BOORD.

[4787.)-SPEAKING TUBES.-Gutta percha is the best of all materials for this purpose.-SIGMA.

QUERIES.

[4788.]-DISSOLVED BONES.-Will some correspondent inform me how to manufacture dissolved bones, and other artificial manures, on a small scale for use in my garden?-J. H. B.

[4795.]—ENAMELLING SLATES.-I shall feel truly obliged if one of your kind readers will be so good as to explain to me the process of enamelling (or japanning) on slates; or inform me of any book on the subject. -Do ME So.

[4796.]-UNIVERSAL SWIVEL GAS-JOINT.-Will
D. Clark be so kind as to inform me what kind of a joint
a universal swivel gas-joint is? Also, what kind a tele-
scope joint is.-ANON.

[4797.)-TUB HOOPING.-I have a great deal of tub-
hooping to do, and I want some one to tell me how to
get the proper level, as I cannot get them to fit properly.
-ANON.
[4798.)-STAINS ON WOOD.-Will some fellow
reader kindly answer me the following, by giving the
reason why some joinery work with which I am con-
nected has, on being stained and varnished, become
covered with black stains, in the form of spots spread
indiscriminately over the surface, but especially over
the panels?-GEOMETROS.

[4799.]-SCIENCE AND ART DEPARTMENT.-Can
any of our technical friends give any information con-
cerning the Queen's medals for subject I.; are students
that have passed in honours eligible for medals?-
L. M. N.
[4800.]-GEOMETRY.-Divide a septagon into nine
equal parts by lines parallel to one edge.-T. STOREY.
[4801.]-GREENHOUSE.-Will some brother sub-
scriber kindly send me a sketch (if our editor will allow
space for it) of a small greenhouse. I want some decora
tive work about it, such as gable boards and carved
top; also, what would be best to heat the same, as I can
have steam conducted to it with little trouble? I want
the house span roof?-BLACK COUNTRY JOE.
[4802.]-WATER POWER WANTED.-Will some
practical person advise a professional man with me-
chanical and farming tendencies? I have two small
farms which could be much benefited by irrigation.
Each has a stream running along the lower boundary.
The stream, though never dried up, is in summer so
diminished that it probably might be conveyed through
a 6in. or 8in. pipe, and then velocity is also very small,
the fall being perhaps 2ft. to 3ft. I want a self-acting
power to convey water, by pipe or otherwise, to the
higher level of 10ft.or 12ft., by means of a pump or other
sufficient lifting arrangement. I have made a rude
model on the principle of a screw within a tube, in-
tended to be caused to revolve by the pressure of water
passing through the tube. The model tube is 19in. loug,
lin. bore; the screw has but one thread, making a coil
of thirty-nine within the length. I am now aware that
the pitch of the screw is not correct, and that a second
or more threads would give more power. Under water
pressure of aft. or 4ft. my model gives a rapid velocity,
but incapable of resisting even very slight obstruction.
D. J.

14803.]-FAURE'S BATTERY.-I have recently pur-
chased one of Fauri's batteries, and shall be greatly ob-
liged if some correspondent will inform me how it
would answer to fill the carbon bottle with a saturated
solution of bichromate of potash instead of nitric acid.

-DEDALUS.

[4801-THE LATE DROUGHT.-Being deeply interested in the progress of meteorological science, I should like to learn whether the late severe drought in the British Isles and in France has also prevailed in remote regions, as in Russia, North America, or elsewhere. As it may have extended more or less over the whole northern hemisphere, I should esteem it a great favour if any brother reader, who may possess notes on the weather or the amount of rainfall during one or more of the past three or four months, or any remarks on the season, from remote stations on the globe, would kindly and briefly inform me through the medium of your columns.-C. F.

[4805.]-HEATING APPARATUS.-Will one of your readers kindly inform me the best way of constructing and heating coil pipes for the warmth of a small office 6ft. long by 4ft. wide? I have in previous winters used the gas-jet, but find it affects my health, without comfort to the feet. I have an idea that a boiler outside the office in an enclosed passage, "now erected," might be heated by gas without being unhealthy, and cause the the place. Advice upon this, or any other method, will steam to pass through the pipes near the floor to warm

(4789.)-MAP.-How can I make my paper map adhere to the linen, as I find the linen absorbs the gum ?-be received with thanks by-A POOR CLERK. BERIRO.

[4790.]-COPYRIGHT.-Qan any reader kindly inform me how I am to proceed in the case of my wanting to enter anything at Stationers' Hall, or any other register of copyright? Whoever will do so will oblige.-Mus. [4791.]-HORIZONTÁL OSCILLATING CYLINDER. -Can any reader refer me to a number of the ENGLISH MECHANIC containing a description of a horizontal oscillating cylinder? If it has not hitherto been described, will some engineering friend kindly explain its mechanism, and assist an amateur trying to make one?-F. A. B. SALT.

[4792.]-PROBLEM.-Will" J. K. P.," or some brother reader kindly solve the following? (a) A force of 100lb. is resolved into two equal forces acting at an angle 602; find magnitude of either component. Aus. 577. (b) A force of 100lb. is resolved into two equal forces acting at an angle of 302, find magnitude of either component. Ans. 517. Please draw figures to illustrate both.ONUS.

[4793.)-IRON SHIP.-Would some of the correspondents of the MECHANIC oblige me with the method of laying down an iron ship (of any size) ?—T. H. ROGAN, Sunderland.

[4794.]-ELECTRICAL.-TO “SIGMA.”—“Sigma" (to whom many thanks), says (No. 281, p. 481), that in cases requiring a large current, as for magnets, &c., the peroxide of manganese battery is "absolutely useless." On the other hand, he states (p. 482) that the sulphate of lead battery "yields a large current," and would therefore, I infer, be very suitable for magnets. Will he kindly inform me whether a 14in. magnet with six convolutions of No. 18 B.W.G. covered wire would, with 3 pint cells of the last named battery, lift Soz. 1-16in., the connections measuring about 10ft., or whether he can suggest any alteration in diameter of wire, number of cells, &c. Also if the battery should be coupled for quantity or intensity. An answer on these points would much oblige, and probably save me needless expense.W. J.

[4806.]-DISCOLOURED IVORY STATUETTES.how to restore the whiteness to ivory statuettes that have Can any of your numerous correspondents inform me become yellow and discoloured ?-WAHSROF.

[4807.)-REFLECTOR STAND.-Would any of your
readers, who has mounted silver or glass reflectors on
stands, inform "a youth" how he could make a stand
(equatorial preferred) for a speculum of about 6in.
diameter? If any friend has got one near Wigan I should
be very glad to see it.-AMATEUR ASTRONOMER.

[4808.]-THE TELESCOPE.-I am a beginner in
astronomy and want a telescope. As I cannot buy "a
good" refractor cheap, I thought I might make a good
reflector for a far less number of pounds than is asked
for a good achromatic. Suppose I had "about" three
pounds that I would lay out to make a good useful
telescope myself, which kind would be the best for
one like me to make if I bought the principal parts ? In
some books I find they are dead against the reflector.
And what size of object glass would be equal to a 6in.
speculum? If Mr. Purkiss, "F.R.A.S.," Mr. Proctor, or any
P.S. I have a small achromatic with a 1g object-glass with
other reader could help me I should be much obliged.
a power of 154 only.-AMATEUR ASTRONOMER.
globe, 16in. in diameter, made by Benjamin Martain,
[1809.]-CELESTIAL GLOBE.-I have a celestial
which getting rather old I had cleaned and varnished,
places; could any of your readers tell me whether I can
but when I came to use it the varnish peeled off in some
get it re-covered, or can I do anything with it myself,
as the paper has also come off in many places. What
would be about the cost ?-AMATEUR ASTRONOMER.

[4810.]-LARD AND SAUSAGES.-I shall be obliged
to any correspondent who will inform me of a simile
apparatus for rendering lard, one that will not require
much attention, and without risk of burning; also the
best way of pressing the "scraps." I should also be
obliged to any one for a good sausage recipe, and in-
structions how to make them.-SHOPKEEPER,

[4811.]-WEIGHT OF WIRE.-Will y correspondent be kind enough to state boys of No. 35 copper wire make a pound; cotton and silk covered?-TOMETUS. [4812.]-VERTICAL SLIDE REST-111* be so kind as to explain a vertical side rezul to fit one up in conjunction with a friend-2 [4813.)-SMALL PLANING MACHINE ago I asked through your valuable jour a small planing machine, and several kindly answered me, but none gave me I desired-viz., how I could make the ter the castings together myself? If one of kind will greatly oblige-ToMETER.

[4814 -WATER SUPPLY.- Will plumber explain to me through our invala be following? I am about laying a pipe frade to our house, a distance of nearly 700 yard calculation. The rise will be 13ft. above th in other words, a pole 13ft. long standing in the the top of it would be on a level with the se Now I should like to know all that is required the pipe. I have seen two taps in the tide ARA similar situation. I want to know what as they ver or if it would do without them. I understa solutely necessary to have a turn-off tap at theve voir, and is it likewise necessary that there d any air pipe; if so, in what part of the pipe show zo The neighbour's one that I have examined cz slower and slower, until it stops altogether, andk ing on one of these taps that I mentioned as beints side of the fountain pipe, and allowing it to racava perhaps seven or eight minutes, when I shr immediately runs faster into the cistern, and contr all right for a week or two, when the same has to be again. Surely there is something wrong. I myse tion there is no air pipe in it, and we are not listed altogether with the plumber's reasons. He says the pipe is holed somewhere, but it is so recently put in I czenot think that is the cause. Perhaps at the same ting you will let me know what the best thing is to gaf a force-pump stuffing-box. Is leather, cut war-clape, any good ?-A.

[4815.]-GOOD REED ORGAN PIPE-Will ABY fellow contributor inform me how to make cred organ pipe? Also the size of pipes required for an st stop, voiced on Adept's" dute principia-A Cus

TRIBUTOR.

R. J.

14818.)-RUBBER VALVE.-How long will vulcanized india-rubber valves staud in the condensing part of a And how DY low pressure steam-engine, usual heat? degrees of heat will they stand without being desto gd, supposing superheated steam were used, and having blow through to obtain a vacuum before starting?— [4819.]-SCIENCE QUESTION.-Will any kind reader inform me how to work the following question occurring in the Science Examination Paper for Honours of las May? Determine the locus of the curve whose equation 2. unit lin.? And which is is (y −2)2 + (r−√2P. the best book for such study ?--X. Y. Z. [4820.]-EBONISING.-Will some one be kind enough to describe the above process for the benefit of CARPAL.

[4821.]-PENDULUM SPRING.-What is the usual method of determining and fixing the isochronism of a pendulum spring, in either English or foreign watches? I have a watch (verge) with the top pivot broker. Will some of our competent brethren kindly tell me the easiest way to put in a new pivot? I have also a watch with fusee arbor square completely off. Is it possible to put in a new square without taking the arbor completely out of the fusee? If so, how am I to do it? If not to be done in that way, can the arbor be taken out of the how are they usually fastened in. I also wish to know fusce and another fixed securely in its place? And if the pinions two and three of watches have their leave turned down to a shoulder with the common graver, and how, in the turns, to form a seat for the fixing of the wheels before riveting on? Al-o what ought to be the relative size of the ferrule to the article turned? Whe you use the bow, how do the faces of wheels in watde receive the smooth surface they generally possess? it turned up with the graver in the turns after the sh is riveted on the pinion, or is it smoothed on the pub ing block? Are there no small lathes in use with wheel and dead centres for turning up watch wheelies pinions? Would they be equal to the bow and is for light work ?-IMPROVER.

[4822.]-LEAD BURNING.-I wish to gather information respecting the art of lead burning. A lescription of the apparatus required, and all messary particulars. Or is there a work to be obtained that will give the necessary information ?-W. C.

[4823.]-STAINS ON STEEL.-I have had some of my polished steel tools damaged by rust, after taking off the rust (by sandpaper and oil) a dark mark remsius. I shall be glad if any of your readers will inform me bow to efface the dark mark,nd restore the original polish. -T. W. U. R.

[4834.]-BATTERIES.-I quite agree with the remarks of John Legg (1. 316, p. 570) in his description of the sulphate of lead battery as regards its constancy, form in which he describes it a patent? Will John Leg As it is the best I have had to deal with, but is not the describe the manganese battery and oblige ?-ROANOKE.

[1825.]-ELLIPTICAL CUTTING FRAME.-Can any of your correspondents tell me how to make an elliptical cutting frame for ornamental turning? I know there has not been anything of the kind described lately, as I have taken in the MECHANIC for some time. Please give with this tool. It is for a 4in. lathe.-J. W. G. tall and complete directions as I totally unacquainted

[4826.]-SCREW CUTTING.-Having a great many screws to make I should be gl1 to hear your correspdents' dodges for getting them done quickly. The

screws are brass and all the same size, with the beads milled so as to turn them with the fingers; about in. long, in. diameter of head, screw. I get them cast in lengths of 12.-J. W. G.

[4827.]-MOTIVE POWER FOR LATHE.-I am in want of a motive power to drive my two lathes, grindstone, drilling machine, &c., &c. Can any one inform me of a cheap plan to drive them (one at a time) as I find treading them very hard work from morning till night? -J. W. G.

[4828.]-SPECULA GRINDING.-TO MR. PURKISS. -Will Mr. Purkiss kindly answer the following questions for me? What should be the diameter and thickness of the brass tools for grinding a perfect spherical curve on a What are the different fineglass disc 4in. diameter ? esses of emery used, and how long ought I to work each kind? How can I tell when the glass is ground fine enough for polishing? Ought the pressure to be light or heavy when using the finest emery? When the tool is covered with a piece of linen rag, and putty-powder is used, how long ought it to take to polish the glass ? Should I press very heavy in polishing? Is it necessary to wash the putty powder as purchased in the shops.

APLANATIC.

[4829.]-TO "INDUCTORIUM."-Will you be so kind as to inform me in what respect is cotton covered fine wire inferior to silk covered wire for induction coils, when both are varnished with shellac or paraffine ?FINE WIRE.

[4830.]-DIAMOND POINTS IN DRILLS.-Will some brother reader tell me how to fix the diamond points in drills? I am told they are soft-soldered in; I have tried it and failed. I could not make the solder take to the diamond.-R. N.

[4831.]-FORCING AIR CURRENT.-I want to force a continuous current of air into a chamber not less than 180° of heat. Any information on the above subject will greatly oblige.-AN ANXIOUS INQUIRER.

[4832.]-PAINTING METAL BATH, TIN, ETC.-Can you, or a brother reader, tell me the best way to paint a hip-bath, so that the paint will not come off very readily with the water? 2nd. What is the process of stoving tin goods? Srd. What paint is best for the purpose?X. Y. Z.

[4833.1-RENDERING CALICO AIR-TIGHT AND WATER-TIGHT.-Could any of your correspondents tell me the best way of rendering calico air-tight and water-tight ?-YELOC CIREDERF.

[4834.]-LINK MOTION.-Would Mr. Baskerville or any other please give a simple rule, showing how to draw in the excentric pulleys for an indirect acting link? -P. B. Mc G.

[4835.]-INDIA-RUBBER.-I find that india-rubber after it has been exposed to the light two or three years loses its toughness. In fact it becomes brittle and use. less. Can any one suggest a mode of preserving the material?-J. P.

[4836.]-ARTISTS' LAY-FIGURES.-Can you or any brother reader inform me how the joints of the patent papier-mâché mannikin or lay-figure used by artists are

put together? Also the best and cheapest method of making a papier-maché suitable for the purpose, and how are they moulded from life ?-G. S. WALSDEN.

A

840 links. The diagonal line from B to C = 1128 links;
the perpendiculars D r 482, A ƒ 210.
N.B. Each person's share of the land to fall perpen-
dicularly upon the side A B, and also the number of links
in length for each person upon the given line AB.-AN

AMATEUR LAND SURVEYOR.

[4813.]-MUSICAL. Would some correspondent kindly tell me where I can procure an old song on tobacco, each verse ending with the refrain "Think of this when you smoke tobacco "?-D. N. E.

[4844.]-NUMISMATICAL. Will onr good friends Mr. Henfrey or Mr. Batty give us some information as to the best practical method of displaying coins in a museum, taking into consideration safety, expense, and educational use, the best mode of affixing names, dates, &c.? If they, or any of our numismatical friends will do so they will much oblige-SAMUEL SMITH.

[4845.]-ELECTROLYSIS.-I have repeatedly tried to effect the decomposition of water by using six Bunsen's cells. quart size, and a common "shocking coil," but have failed. Will "Sigma "be good enough to put me right ?-Work,

[4846.]-LOGARITHMS.-Will any brother reader kindly solve the following in full?-Given log 75014 8751423, log. 7.50158751481, find the number corresponding to logarithm 3-8751462. Ans. 007501467.WORK.

=

[4847.]-NATURAL FORCES.-TO" SIGMA."-I desire to thank Sigma" for his ready, kind, and complete answer to my letter, and if I do not trespass too much on his time I should feel obliged if he would indicate a book or books which show or treat of the relations of the forces of nature. I have only studied electricity for a couple of years, and of course am not quite so clear on the subject as I should like to be; however, I cannot help thinking that it is intimately connected with heat, and am very anxious to read a good authority on the subject. I have read a great number of smaller books; but none of them seem to generalize. I should also feel greatly obliged if "Sigma," or any other reader, could give me a tolerable description of the machine which Professor Jacobi (in 1834) constructed to propel a boat on the Neva.-THINKer.

[4848].-HYDRAULIC APPARATUS. Can you or any of your correspondents inform me what the probable cost would be of furnishing and fixing, ready for use, a hydraulic apparatus of, say, half a horse-power; and secondly, what would be the approximate cost per diem for working this power, the water being supplied by meter. The above is required for working a small printing machine.-SUNDERLAND.

impregnated with the gold and silver. A certain experiment is used to clean the plates. The plates are painted with a solution which is black, and exposed to a certain heat, after which the gold comes off in a thin shale. What is the solution and proper mode of operation to effect the same ?-J. RUSSELL.

[4853.] GEARING FOR BUCKET.-I shall be thankful for a simple rule for striking a pattern or gearing for a bucket, such as used in a drawing lift (or pump), say for a 9in. or 6in. working barrel.-J. RUSSELL.

[4854.]-SWIMMING PADDLE.-Some time ago I constructed a swimming paddle, which for some reason or other does not answer the expectations I formed of it. My original intention was to work it entirely under water, and I thought to avoid the drag of reflex action by placing the blades at right angles to each other, and feathering at each stroke. I soon found this plan would not answer, since it necessitated a change in the position of the hands, which weakened the pull. On the next trial the blades were made to correspond in position, being lifted out of the water alternately, but even then candour compels me to admit that it is quite as much a hindrance as a help. Will any reader kindly tell me what they think to be the cause of failure, or whether in their opinion longer practice with the paddle might render it really serviceable as a means of progression in the water ?-PERCY JOHNSTONE.

[4855.]-BATTERY CONNECTIONS.-I have twentyfour Grove's batteries, and am puzzled as to making the connections. I have tried slips of copper, bent tight on I do not to the platinum, but this tears and wastes it. wish to incur the expense of purchasing binding screws, and unfortunately I had the platinum cat too short to allow of its being bent over against the next zinc. If any brother reader could inform me of some simple method I should be greatly obliged.-R. T. BELL.

[4856.]-WENHAM'S PARABOLICAL REFLECTOR. -Would Mr. Pocklington say if Wenham's "paraboloid reflector" can be used with low as well as with high powers? The idea mentioned by your correspondent A. A. F." of organizing an "English Mechanic Microscopical Society "is, I should think, a good one, and will, I do not doubt, be acceptable to many of your subscribers.-A. L. B.

[4857.]-MODEL WINDMILL.-"John James" (see 4605) will oblige if he will say where his model windmill can be seen, or give a sketch in your paper; also cost for a boat 25ft. long and 5ft. 5in. beam-İNQUIRER.

[4858.]-THAUMATROPE.-Will some one tell me how to make a thaumatrope ?-J. M.

[4859.]-LOCOMOTIVE DRIVING.-What is the cause of a train progressing by a series of jerks? Is it due to bad driving or bad management of the firing ?STEAM RIDER.

[4860.]-REGULATION OF COMPASS.-Will any one tell me how the compass is tested and regulated in iron ships? Is it absolutely necessary to put the ship with her head to the north ?-NAUTIS.

[4861.]-INCLINE.-What degree of inclination would

stop a locomotive drawing four times its own weight?—

Can

S. B.
[4862.]-LEAD POISONING.
any of your
readers furnish me with an antidote against white
sugar of lead poisoning ?-W. E.
[4883.]-GLASS ANALYSIS.-I shall feel obliged if
Mr. G. E. Davis will give me plain directions for
analyzing glass.-J. M.

[4864.]-MANGANESE BATTERY FOR IGNITION OF POWDER.-Will" Sigma" or Mr. Jarman kindly inform me whether they consider that six quart-cells of this battery would suffice for the purpose of iquiting gunpowder? In that case would a piece of platinum wire passing through the powder effect the explosion, when the circuit was closed? I also wish to know whether constantly shifting batteries about, taking out of their boxes, &c., in any way effects their electrical condition ?-C. H. B.

[4849.]-MEDICAL.-Would any brother reader give [4837.] FOREIGN WOODS.— Being desirous of a simple test to find whether medicine in a liquid or obtaining information concerning many foreign woods other form contains mercury ?-PATIENT. which are available for the uses of the ship-builder, [4850.) THE TELESCOPE.-I wish to thank Mr. carpenter, and cabinet-maker, I should be much obliged Purkiss for his very kind and complete reply to me with if my fellow readers could direct me where I can find respect to the size of the flat. Mr. Purkiss has in his printed descriptions of the properties of any or all the letter supplied valuable and plain information that will following woods--some of which were in the International be useful to many of our readers, and which has never Exhibition, or any other woods especially suited for been so supplied before. I had before writing to him cabinet work, with which they may be acquainted, or adopted a fifth, but I believe a sixth is generally used. by their assisting me in my endeavours to acquire I had a wish to know his own plan, but as he justly obknowledge by describing their properties in the pages serves, a fifth or fourth gives a little play. I now wish to of the ENGLISH MECHANIC, Should you, Mr. Editor, think draw his kind attention to another matter. I have tested a the subject, which is really an important one, worth the 10in. mirror of my own make with his bar test. I used space. Blue mahogany of Jamaica, bay, beet, beef, a power as high as 640, which the mirror stood perfectly bergamot pear, cainphor, canary, cocus, lilac, iron woods well, both before silvering and after, and on the brightest (very various), purple wood, red sanders, sandal, sassafras, stars, and yet I cannot get a good definition. I have satin, sabicu, zebra. American woods: Elm, black oak, tried the test over and over again, and with good air white wood, mangrove of Trinidad. African woods: Oak, (for I had my refractor out the same time) and each mahogany, green ebony, Australian woods: Blue gum, night trying it on the stars and Saturn, and it will not cedars, mahogany, red wood, iron bark, stringy bark.—give a star disc nor show the division of the planet's ring. I invite Mr. Purkiss' opinion as to whether bad flat would not allow a good mirror to show the test-bar straight and parallel, and what effect imperfect centering would have? There was one thing I particularly-STICK-IN-THE-MUD. noticed, the edges of the bar was not seen sharp and well defined like a sharp and distinct shadow, it looked

LIGNUM VITE.

[4838.]-PEDESTRIAN TOURS.-Will" Scholasticus or any other of your readers give me some suggestions as to the best direction in which to walk under the following circumstances:-A friend and myself intend making a five days' tour at the close of the present month; my friend takes considerable interest in architecture, especially that of the cathedral type, while I on the other hand take more pleasure in the attractions of scenery. We wish to select a walk (of not more than 25 miles a day) which will give satisfaction to the tastes of both, without making more than a very limited use of the railway or other means of conveyance. London is to be our starting-point. "Scholasticus" has kindly offered information as to "good and cheap houses for sleeping, &c.," and I think any such hints would be of great service.-F. P. P.

[4839.]-CANNON-How can I alter a muzzle-loading Will some kind reader

cannon to a breech-loader ? oblige?-GUNNER.

like the shadow of an object (say a penholder) when held nearer to a lamp than to the white blind on which I projected its shadow. I expected to see the shadow of the test-bar sharp and distinct as when the penholder is held near to the white blind. When I looked at Jupiter, there seemed to be a round shadow of the planet on one side; this shadow was not seen only when the planet was a little out of focus (inside the focus). I have sometimes seen the same appearance with the stars. Now this would seem to prove that my mounting was not good, and that the mirror gave a double image, which from the pains I took in mounting the mirror I am not willing to admit. The flat I have used is only a piece of ordinary plate glass, not select pieces. How does Mr. Purkiss succeed in silvering after failing a few times? First, I was [4840.]-GUNPOWDER.-In Mangnall's" Questions on History"itis stated that gunpowder was invented by one induced to depart a little from Browning's directions, and Schwartz, A.D. 1310. have always siace succeeded in getting excellent films, I have always understood that it was known and used in China and other eastern countries but they are always slightly transparent. I think this should not be the case as there must be some loss of long before that date. As Margnall (who is considered light. Would it not be advisable to strengthen the silver an authority) states this with any reservation or solution a little, and so get thicker films? Lastly, can qualification, I shall be glad i ny of your learned Mr. Purkiss, or any other of our able correspoudents, tell readers can throw any light on this subject.-STUDENT. me whether a truly parabolical mirror will converge [4841.]-SPONGES.-Can any one tell me how to rays to one identical focal point from objects at any preserve sponges? I use one daily in a sponge bath, distance, as well from an object at 50 or 60 yards, as and find that in about a year's time it falls to pieces.D. N. E.

[4812]-LAND QUESTION. I have a small parcel of land (which 300258 square links) to be equally divided between four persous, but as the sides of the piece of land are very irregular I find it somewhat difficult to who will be able to solve the problem for me. I give an divide. Perhaps there are some readers of this journal illustration of the piece of land.

=

AB 1033 links, A C = 241, C C 630, and B D =

=

from the stars?-G. C.

[4851.]-AEROSTATICS.-To what space a quart or
gallon of common air can be compressed, and what ex-
Also whether there is
panding power that would be?
any gas (gases) or fluid more compressible, and with
a greater expanding power ?-J. R. L.

used in connection with our gold-crushing machines,
[4852.]-GOLD CRUSHING.-Copper plate being
the copper is coated with quicksilver to retain the gold
as it flows over the same with the water and crushed
material. After several months' use the plates become

[4865.]-LACQUERING BRASS WORK.-Can you tel me how to lacquer small brass work so as to improve and brighten the metal? I find the lacquer dulls and spoil the work, rather than do it good. I made the metal warm and applied the solution with a camel-hair brush, but the surface comes out so dull that I must be wrong somewhere. I used what is called best gold lacquer; if this be the right stuff, please tell me how best to use it?

[4866.]-WATERPROOFING TIMBER ROOFS.-I should feel obliged if any of your readers can inform me how to render a wood roof of shed 40ft. long waterproof. I have tried tar and sand, and after bags nailed on and tarred. I want something cheaper than felt.H. SEYMOUR.

the

[4867.] AUSTRALIAN NUGGET. - Being possessor of a small nugget sent to me by a very dear friend in Australia, with the request that I would have a hoop made of it and wear it for his sake, and being anxious that the hoop should be made from that particular piece of gold (without the slightest doubt) I wish, if possible to make it myself. My object in troubling you is to inquire if any of the readers of your invaluable paper will oblige me with a description of the process required to accomplish the object I have in

view.-A NEW SUBSCRIBER.

[4388.)-TRUMPET STOP.- Will any harmonium correspondent kindly inform me whether a trumpet stop (worthy of the name) has yet been introduced on the harmonium; and if so, by whom, or on what maker's instruments to be found?-RARA AVIS. [4869.]-LENGTH OF PENDULUM.-I have the movements of a clock, the escape wheel of which has 45 teeth, and it revolves once per minute, making in that time 90 beats, each beat, therefore, recording to my calculation, being two-thirds of a second; now I wish to know what length the pendulum should be? I purpose making the bob of a brass cylinder, about 2in. in diameter and 4in. long, filled with lead, and the rod of seasoned deal, well varnished. I understand that "the root of its length," but not being up in mathematics I time of vibration of a pendulum varies as the square cannot find the length for myself, and will thank any of my fellow readers for the information.-ELECTRO-MAGNET, No. 1.

All communications should be addressed to the EDITOR of the ENGLISH MECHANIC, 31, Tavistockstreet, Covent Garden, W.C.

The following are the initials, &c., of letters to hand up to Tuesday morning, September 6, and unacknowledged, elsewhere:

W. and T. P., R. F., R. R., J. H., P. C. V., J. O'Connell,
Edward B. Fennesey, H. Pocklington, J. R. Allen, Ed.
James, T. W. B., Rev. E. Kernan, James Williamson,
T. C., W. Kimmis, J. B. Primas, H. P., A Young Man,
George, Welby, R., Unit, Argent Sable, J. J. B., F. B.
White, Zeta, Espérance, Alpha, Scraper, S. Dixon, G., A
Student, Totnesian, Deri Errac, Cuthbert, T. B, A
New Subscriber, A. S. C., G. W. A., F. J. Walker, R.
N., Harry G. Newton, A. E., E. W. A., M. W. G., Pater-
familias, Ivory, Vulpecula, H. P., G. Valentine, Cabinet
Maker, C. H.Wynn, Mechanician, T. L. H., J. Á. M., Au-
gustine, Thos. Fletcher, Argus, Farmer, A Mere Novice,
A Runaway, Z., G. J. W., T. A., A. Childs, Scio, Idea
Cather, W. Pocklinton, H. H., H. W. Henfrey, J. A. H.,
J. Andrews, Student, Rupert, John Hewitt, G. L., H,
W. Reveley, R. D., A Morayshire Man, Mr. Batty, Epps,
A. P., W. E. D., G. Prew, J. E. Y., E. Cooper, Atomic,
Chemicus, Quill Pen, R. A. M., T. M. Simkiss, North
Pole, Graham, F. S. H., Sigma, J. K. P.

HENRY W. HENFREY, of Brighton, says :-"I think that
with such improved printing, engraving, and paper,
the ENGLISH MECHANIC ought soon to double its cir-
culation."

THE PHANTOM WHEEL.-Additional letters confirming
the views of preceding correspondents, from
"Bicycleist,"
," James Thompson, and J. R." They all
repeat the same story, that the "Harmonious Black
smith" spoke from insufficient experience.

W. S. OWEN.-Advertisements for Sale Column must be
prepaid.

MR. BROWMIDGE.-We don't answer queries through the post.

T. H. SOMERVILLE.-Next week,

T. O'CONNOR.-All received from you has been inserted. J. H. N.-Thanks. We have had to many series of articles of late, and cannot promise to insert yours at present.

Les Mondes of somnambulism being perfectly cured by T. W. BOORD thanks "Urban" for pointing out the