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The height being 1ft., the velocity through his pipe will be Sft. per second; therefore when the pipe is 9in. in diameter, area being 63.6in., the discharge per second will be 6107-25 cubic inches.-STREBOR.

[1859.]-MATCH MAKING.-Mr. Ch. Mertens, at Lessines (Belgium), patented three months ago in that country, his lately invented dipping machine for match making.-RAIMOND STAES.

[1865.]-WHITE METAL BEARINGS. When the chair is cast, have it hollowed so that it will hold the metal, fasten the chair in its place, put in the spindle packed up, put some clay round the spindle to keep the metal from running out, pour to the centre of spindle, cut off any projecting metal, lay some strips of cardboard on each side of the spindle, put on the top part of chair clay round the spindle as before, and pour through oil hole. This mode requires neither fitting nor boring. I have seen lead used alone, and wear very well.-MILLY. [1887.]-PUTTY.-Let "Hortus" get about 201b. of whiting, and pound it up fine, then add enough raw linseed oil to make it into a stiff uniform dough. I found it took three pints, and that was not quite enough. Then hammer it well out, as thin as it will go, and work it well till it comes soft enough. I was told that one pint of oil was sufficient for 151b. whiting, but found three pints hardly enough. This is the best and cheapest putty. He had better add the oil as he wants it-not all at once, and warm the putty before

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[MARCH 25, 1870,

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a great profit. A hole is made in the shells, and
they are strung on threads of palm fibre; 40 sheils = 1
string. Many merchants in Lagos occupy eight
cowries weigh 80 or 90lb., the white Indian ones 35 to
or ten girls stringing cowries. 2000 blue African+c)..
40lb.; 2000 about a dollar,-BERNARDIN.

"Notes on

[1896.]-EQUATION.-In the last number of your
paper, page 640, C. H. W. Biggs announces his inten-
tion" in a short time to commence" his
Algebra." Permit me to express a hope that "C. H.
W. Biggs will first master the question before under-
taking to teach others, otherwise those readers of the
"Notes," will be in danger of falling into errors, as,
ENGLISH MECHANIC who put their trust in his
for example, that the square of 5x + 10 is 5x
10; or that

175

4

7175
2

See reply by C. H. W. Biggs to [1896] Equation. page
615. The reply by "Hugo" to same Equation. same
page is quite correct. -SENIOR OP.

Wood's Algebra, he will find in the chapter upon Quad1896.]-EQUATION.-If Mr. Biggs will consult ratic Equation, page 118, the equation fully discussed in its unaltered form: x + 5 + 10 = 8.-H. C. C. stone into twelve oil stones when I was an apprentice, [1910]-TURKEY STONE.-I cut a lump of turkey partly with a sheet of copper, and partly with a sheet of lead, of course fitted to wood frame for convenience, in both cases with sand and water, but I cannot [1889.]-BELGIAN AND FRENCH PERIODIremember which cut it quickest.-JACK PLANE. CALS.-No journal similar to our ENGLISH ME[1913.]-GAS BURNERS to burn common coal gas CHANIC is published in Belgium or France. are not of much use to illuminate dissolving view apone, such variety of instructive matter is to be found. paratus. I have tried several, including a 50-hole ar

a fire.-AUGUSTUS.

In no

effective. My experience led me to adopt the improved
oxyhydrogen burner when I want more light than oil
will give; the apparatus is very simple and quite safe.

a-c

=

c-b

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From (7) and (8) by transposing and dividing,
a2 + b2 - c (a + b) − (b − c) z
a2 + c2 -
whence, by multiplying up and reducing,
b (a + c) (a - b) =
z (a2 + b2 + c2-ab-bc- c a) = a3 + b3 — c — 2 a2
c+ 2 ac2 - 2 b2 c + 2 b c2 - abc
whence, dividing each side by the co-efficient of e, it
will be found that z = a + b - c. I should be glad to
see a neater solution from some abler pen than mine.
-SENIOR OP.

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in several foundries in Glasgow; it is better than
The following is what I have seen used with success
beeswax :-When the pattern comes from the finishing
[1970]-VARNISH FOR IRON PATTERNS.
shop smear it all over with oil rubbed on with a bit
of waste, put it in the drying stove all night, so as the
repeat the dose. I can recommend this, having seen
oil will burn in; if not in a hurry for the pattern
it done and having done it myself pretty often.-N. L.
[1978]-LIQUID GLUE-I have made a strong

as they respectively and for the most relate to some gand, but always found camphorated colza oil more liquid glue by treating Russian glue with a little special branch of science. If my fellow correspondent "Argente" will communicate with me through our MECHANIC What subject he more especially prefers, or what branch of science, mechanics, or technology, he wishes to be informed on, I shall be glad if I can to answer his demand.-RAIMOND STAES.

communicate it to our ENGLISH MECHANIC

-C. WARD.

[1929]-LACQUERING.-In answer to "Inquirer," I beg to send him the following method for lacquering [1894] CHINA GRASS DIVISA.-I have also brass-work. If he is going to proceed on old work he been puzzled by tha: name, and never could get any must first boil the articles in strong soda and water, conclusive information about the plant; the followso as to get off the dirt and old lacquer; then scrub ing article appeared in several French reviews: them with sand and rinse them. The next process is "Dr. Grothe, director of the manufacture of Ram- the dipping, for which he will require an earthenware melsberg, near Berlin, employs with great success, for pan capable of holding the articles, which he must fill making figured stuffs, much in demand for England, 2 pails of clean water and a box of sawdust. If he yarn of China grass, white or dyed in different has any means of keeping the sawdust hot all the with aqua fortis, which he can obtain at any chemist's; colours. He produces the China grass divisa (sic) in a plantation he planted, and which yields 50 per cent. better, and a nice clean brush. Now he will have to dry fibre, and 30 per cent. long and very fine filaments. proceed as follows:-Tie the articles on copper wire, In the mountainous regions where the soil and the dip them in the acid, then rinse in the water and well severe temperature form a serious obstacle to cultiva-rub them in the sawdust till thoroughly dry, and tion of flax, the Urticacea in general, and the China then brush the sawdust off. grass in particular, resist perfectly. (?) The Prussian that want relieving this must be done with a bright If there are any parts Mining Office Los taken into serious consideration a articles are ready for lacquering; but if the articles steel burnisher and a drop of stale beer, then the culture which seems to fui nish an accessory and very have tarnished, to restore their brightness he must precious resource to the miners of the Harz and of dip them again, but he must dilute the acid with ten Hanover." I made several inquiries, but always times its weight of water, rinse and dry as before, failed. I even wrote to Dr. Grothe, but did not receive any answer. If later I learn anything, I will beat them on; a plate of iron with a gas-burner under Now for lacquering them he wl want something to posed also that divisa might be a fault of impression If he wants that red gold tint on his articles, it is best I supit will do; but if he has an oven that will do as well. for dioica, or for diversa, different kind.-BERNARDIN. [1895.]-COWRIE COINS.-The following letter lacquer with it; he must heat the articles so that he to get French gold lacquer and mix a drop of red from Lord Alfred Churchill, to the Secretary of State can just bear the hand on them, and then with a soft for the Colonies, which I extract from the "Technolo- camel-hair brush lay the lacquer lightly on, care being gist, of July, 1865, deals with this subject:-"The taken not to lay it on too thick or to get the articles Council of the African Aid Society have had under too hot. their consideration the recessity and advantage of wants to know, I shall be happy to inform him.If there is anything else that Inquirer" finding some metallic substitute for the cowries, W. SEABROOK. hitherto in use among the natives. A currency ought to be adapted to all the wants and habits of the people for whose use it is intended. Cowries, as a circulating medium, have been for a long time in use in the countries of the Bight of Besin and the Niger territories. Since the annexation of Lagos to the British crown, all the English coins have been introduced there. They are coming into use among the natives, but do not suffice for the general wants of that portion of the community. The lowest English coin in circulation is the farthing. The value of this is 30 cowries, but a great many articles of daily consumption are purchased much below that price. Unless, therefore, some smaller coin be introduced, cowries cannot be abolished or replaced as a circulating medium. In the interests of progress and civilization, of which Lagos is an outpost, it is desirable that the currency should be solely metallic. The Council of the African Aid Society have had an opportunity of seeing the small coins-one mil each-now being struck at Her Majesty's mint in London, for Hong Kong being each one-twentieth of a penny, or one-fifth of a Those coins farthing, would be the value of six cowries. thing worthy of mention can be bought for a lower sum FISH. than six cowries, those coins would respond to all the minor wants of the native Africans, while their being [1964]-CARPENTERS' PRICES.-I have put up perforated, so as to enable them to be strung as cow-fencing of four railings and one stake post: have mor ries are now strung, would render them equally safe tised the post and pointed the railings for 6d. per and convenient as cowries, while they would not be length, but they were 10ft. long, that however is immore than one-seventh of the average weight of the material. The posts and rails had to be put up, but if smallest cowries used in the interior trade. The Coun- put up at per chain it would make a considerable difcil of the African Aid Society beg leave, therefore, to terence; they were laid out on the work ready for use suggest to Her Majesty's Government that it would gratis.- UNLEARNED PLATELAYER. be advisable, and of general advantage, to introduce perforated coins of a similar size and value, in the | 100 for mortising; 1d. per pane of 4 rails for chopping [1964,3-CARPENTERS' PRICES.-Posts, 12s. per

As no

[1931]-LINCOLNSHIRE IRON.-I beg to inform "R. W. M.," that the ironstone of this district contains in its raw state from 30 to 25 per cent. of iron of a very good quality. The average price for the ore in Waggons at the mines is from 4s. 9d. to 5s. 30. per ton, and 5s. 3d. to 58. 9d. per ton delivered at the nearest wharf, Should "R. W. M." require further information, I shall be glad to help him.-BLAST FURNACE ENGINEER, Frodingham.

[1934.] LOGARITHMS. - To
Chambers' "Tables of Logarithms," contains seven
"Y. P. W."
figure tables of logs., log. sines, cosines, &c., and natural
sines and cosines, with a heap of other information;
proper title "Mathematical Tables," gives a few
examples at commencement to explain the tables, has
no treatise. Can be had anywhere for 38.-MATY.
[1954]-CEMENT FOR PARAFFIN LAMP.-Let
it by the fire in a tin cup, to which he may add a small
Noodle
get twopennyworth of shellac, and melt
melted he then may fill the brass socket and stick in
drop of water, to keep the shellac from burning. When
his reservoir; he will find he has a good job.-LING

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lowing, I think he will find one or both [1981]-ENAMEL.-If Mr. Walker will try the folpurpose:-No. 1. Oxide of tin 6, flint 3, borax 1. No. 2. Oxide of zinc 2, Cornish stone 8, whiting 1.—IOTA. [1985.]-SIDE LEVER ENGINE.-I beg to inform Suffold Amateur" that the side lever engine was purposes. I think it was invented by James Watt, but that which used to be almost entirely used for marine I do not know if he patented it. The principle of this engine is similar to a beam engine, only the beams are nected with the piston by means of a cross head and down at the sides (of the engine,) and they are conlevers is connected with the crank. The advantage of connecting rods. The other end of the beams or side this kind of engine is that all the moving parts are the beam to the crank is very long, therefore motion is balanced by each other. The connecting rod from little strain. The heaviest parts of the engine are transmitted to the crank very equally and with very tages are that it occupies a very large space, it is very brought very low down in the boat. The disadvan-H. CHAPMAN. heavy, very costly, and not applicable to screw boats.

counting the number of steps in walking, not much in [1987.]-WHAT IS IT?-It is a pedometer for and is soon ascertained by counting a few mile stones the walking rate is nearly uniform for each individual. use now. Time tells the distance travelled over, for once or twice.-H. W. REVELEY, Reading.

46

[1987]-WHAT IS IT?-I believe the instrument worn in the waistcoat or other pocket, and measures "Querist "has got hold of is a pedometer, which is tion of the weight, which acts in one of the toothed the distance walked. Each step taken causing a vibrawheels.-IOTA,

would stamp the books in gold for a very small charge,
[1989.]-NUMBERING BOOKS. A bookbinder
or the numbers might be painted on the backs in oil
colours, black figures on a white ground.-IOTA.

but blot immediately with blotting paper; a few hours
[1989.]-NUMBERING BOOKS.-Gum the back of
after size with common size or glue water, let this
your paper, write your title numbers, &c., in good ink,
thoroughly dry, and then varnish with pale copal, cut
up, and stick on in the ordinary manner. Of course
when done this may be termed everlasting.-S. T.
we suppose a sheet or a few sheets to be done at the
same time to be worth this amount of trouble, but
complete work on this subject is that by Dr. Percy. It
[1990.]-METALLURGY. -The most recent and
is published by J. Murray, price 218.-BETA.

[1991]- CANVAS CANOE. -I would persuade our friend against making his canoe of canvas on ribs; it is impossible to obtain good lines, or in less boat would consist of straight lines as nearly aptechnical words, no curve can be obtained; the outline proaching the curves necessary as is posible in lessening the distance of the point of attachment to the frame, but the result is in the highest degree unsatisfactory.-S. T.

keel and fixing stem and stern-post, let" S. F." make [1991.]-CANVAS CANOE.-After laying down the

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three or more templets to be placed across the keel at
evals. These templets represent transvere sections
of the boat at their several positions, and to them are
saled temporarily the slips forming the skin or outer
picking. These run longitudinally from stem to
, and may be wide and 11" apart. "S. F." will
and this the best plan, as without the slips the canvas
apt to bag between the ribs. The ribs or timbers
ure steamed to make them pliable by placing them in
wooden box connected by a tube with a common
pot covered with a close lid, or they may be boiled in
water till soft. They must be put in hot, and nailed in
position at once, or they will stiffen. They can be
nailed on the keel with common copper nails, which I
should advise in preference to iron. There should be
arim or gunwale round the boat, as it strengthens
her considerably. I have used canvas myself for a
covering, but find it retards the boat by its friction,
and believe good strong duck would be preferable."Young Wife" may clean them by rubbing them over
After nailing on, give it three or four coats of white
lead. 6ft. is too short for a canoe; 10 or 12ft. is little
enou h, with about 2ft. 6in, beam.-STEERSMAN.
(1995.]-DEFECTIVE PIANOFORTE.-Let a good
joiner let in a piece of hard wood a suitable width
where the crack exists, screwing some good screws
with a sharp deep worm in the joint itself, the worm
or thread of which will hold sufficiently tight to pre-
vent the piece inserted from drawing up by the tensio
of the wires.-S. T.

is done in kiers of wood or iron heated by steam. The 1st requires about 4 to 6cwt. of lime made into thick cream, and freely sprinkled amongst the waste as it is thrown in the kier. The washing requires plenty of water, and is done in ordinary dash wheels. After being washed the waste is steeped in a solution of muriatic acid in water (2 to 3 per cent. of acid), then drained and sweetened by placing under a shower bath, using plenty of clean water. The 2nd bowking is done with soda ash, and takes from 3 to 5cwt. of ash per ton of waste. The drying is generally commenced in an hydro-extractor, and then finished in a stove or the open air, which is preferable. If "NO" desires further information I shall be happy to give it to him.-FEU FOLLET.

[2022]-VENEERING.-Soak your glue until it gelatinises in cold water, carefully boil in proper gluepot, warm your veneer; all the rest depends on three points of detail- cleanliness, close contact of the surfaces, and the expression of all excess of the glue -i.e as small a quantity really between the surfaces o be united as is practicable.-S. T.

[2023.]-AMALGAM-Kill some mercury with pure tin foil; when it has lost its quickness apply with small quantity only of clean tallow.-S. T.

[2023.]-AMALGAM-Mix your amalgam with as much lard as will make a thick paste and spread it on the cushions with a knife.-GITCHE MANITO. following useful:-Melt together 20z. of tin, 2oz. of zine, and 6oz. of mercury; when cold, powder and mix with 4oz. of lard, and loz of bees-wax.-BETA.

[2023.]-AMALGAM.-"T. O'Connor" will find the

condensers 3in. brass cells is from 14s, to 15s.
[2021.]-MAGIC LANTERN-The price of double
hill, or Pumphrys, of Birmingham, may be relied on
optician will supply them, but Cox, of 25 Ludgate-
for quality and price. I have seen a 4-plate portrait
lens used with good effect, but "Guernsey" writes
from personal experience, therefore with authority on
the subject."The Magic Lantern, and How to Use

make up
his weekly report, and send to the architect,
draw most of the working drawings, and measure up
all extra work; in fact, he is nothing more than the
superintendent of the work in the absence of the ar-
chitect.-DELTA.

1994-FILLS.-" Wry Face" finds it a difficult matter to take pills in the ordinary way. Nothing is better than an oyster; it is a capital thing to carry a pill to the stomach Use it in this way-Slit the thick part of a native oyster and put in the pill, then swallow the whole. Children who are foud of oysters, and who cannot be made to swallow pils, may be thus effectually deceived. Another mode of taking offensive pills, or nauseous medicines, is to prepare the mouth beforehand by seme aromatic substance; for instance, chew a clove or a piece of orange peel or lemon peel, or in lieu of this first put into the mouth a bit of alum.-TAUTAU.

[2043.]-PILLS.-In reply to "Wry Face," there are several plans for rendering pills tasteless. Some of these plans are patented, some not. The principle aimed at in all is to cover the pill with a film which shall resist the action of the saliva during the short time that the pill is in the mouth, but that shall be removed in the stomach. metal, as gold or silver leaf, or a varnish composed of This film may be either balsam of tolu, or some similar substance dissolved in spirit, or a coating composed of mucilage of tragacanth and sugar. I have repeatedly been told that coated pills have passed through the whole length of the intestinal tube, and have been passed unaltered through the system. Under these circumstances I leave your correspondent to judge what good they had done. A plan which I myself have found very efficacious is to screw each pill tightly up in fine tissue paper or cigarette paper, cutting off the superfluous material. A similar plan is adopted with balls for and I am glad to see the quotation from "Montaigne The ENGLISH MECHANIC improves, restored to the head of the Correspondence columns. -ARTHUR W. BLACKLOCK, Newbridge, Hardgate, Aberdeen.

dogs and horses

is mistaken in supposing that it is merely water in the
[2057.)-ZINC PLANT.-"A Late Subscriber, E. S,"
bottles in which zinc trees are made. It is a solution
of acetate (sugar) of lead, in water that is used for
the cork of the bottle long enough to reach to the bot-
that purpose. A piece of copper wire is attached to
of wire across, you finally fasten a small lump of zine
tom, and if you want brauches to your tree put pieces
on to the top part of the wire. take care that it is im-
few days your tree will be complete.-HENRY CHAP-
mersed in the solution, cork up your bottle, and in a
MAN.
rium manufacture consists in having a rabbet for the
[2059.]-AQUARIUM.-The great bugbear in aqua-
glass instead of a groove, the former entailing trouble
and vexation without end. Take, then, a groove, and
make the putty of red lead and copal varnish; in a
few days all is hard, sound, and insoluble
must be used as made, as it sets very quickly.-S. T.
The putty
fish of any kinds in my aquarium for years: it is put
[2059.]-CEMENT FOR AQUARIUM.-I have kept
together with red lead putty, common putty is useless.
Red lead putty is red lead (in powder) worked up well
with white lead (in oil) as stiff as it can be conveni-
PLANE.
ently used; leave it a few days to harden.-JACK

[2063.]-MEASURING TIMBER-Numerous works
generally speaking one work is as good as another.
have been published on "Measuring Timber," but
Of course everyone will recommend his own or the one
Aitkin's tables are as good as anybody's. Cost I think
which he has been most accustomed to use. I have been
48. 6d.-GITCHE MANITO.
for sometime in the timber trade, and find that

should obtain "Hoppus's Measurer," price about 28. It
[2003]-MEASURING TIMBER.-R. Livingstone
may be obtained at a second-hand book shop for con-
siderably less. - JONATHI.

of vibrations per second, of the mean rays of the seve
[2004]-QUESTION ON LIGHT.-The numbers
ral colours of the spectrum are, in millions of millions
indigo 686, violet 725.-ERNEST.
Red 497, orange 528, yellow 529, green 601, blue 618,

[2043] PILLS. First see that your pills are thoroughly dried, then stick each with a pin the head of which is bent down like a pot-hook f; now dip the pills one at a time in a strong solution of gum arabic and hang on a string to dry in a warm place. This will not only render the pills tasteless, but prevent the deliquescence some kinds are subject to.-S. T.be ready for use. [2043.]-PILLS.-If "Wry Face" will apply to any chemist, he will find that his grievance can be remedied without much trouble or expense.-BETA.

[MARCH 25, 1870.

little bit of nit. silv. to replenish waste from kaolin,
I shake it well, and then filter, afterwards adding &
and filter. I have sometimes, especially after using
abore entirely removes it.-Mus.
a lot of paper, seen the bath nearly black, but the

Vicar "adopt the plan of cutting his stencil plates ont
[2070.3-STENCIL PLATES.-Does our friend" The
of thick foil (an alloy of lead and tin) If so, great
freedom may be gained even in the repetition of the
same design by departing from the strict geometrieal
lines. In cutting a fresh stencil plate even from the
be exaggerated to give greater ease. Metschroma-
old pattern, an apparently accidental deviation may
but there is none of the richness of colour obtainable
type has been used for the purpose named in Leipsic,
obtainable at shops in Oxford-street on either side of
by stencil colouring as to decalcomanic transfers are
the Regent-circus; but the writer has never seen any
melting together about equal quantities of common
subject suitable for the purpose named.-S. T.
black pitch and rosin
[2072.] PITCH. Shoemaker's wax is made by
small quantity of a common oil is added, to soften the
compound.
When thoroughly melted, a
of the year, more in cold and less in hot weather.
The quantity of oil depends on the season
make it lighter in colour it is drawn out by the hande
An article called prepared pitch is now sold by the
trade; it merely requires to be melted, and the oir

added.-CRISPIN.

To

have one in daily use that was repaired some months [2073.]-CEMENT FOR PARAFFIN LAMP.—I ago with white lead. The white lead must be goodie., free from baryta, its common adulterant, and the lamp must be laid aside for at least a week or two. -S. T.

posed sweating is a condensation of vapour or atto[2075.]-WATER-PIPE SWEATING. The upspheric moisture on the surface of the pipe from the lower temperature of the water contained therein.

-S. T.

send you diagram of Varley's patent coils used in Pest [2079.]-VARLEY'S PATENT COIL.-Herewith I

difference in this coll
Office instruments. It
coil itself. The only
is same size as the

gamate zinc plates, clean thoroughly with diluted muriatic acid; pour the mercury on, and spread it [2066.]-ZINC PLATE FOR BATTERY.-To amalover with a brush; allow them to drip, and they will is the needle and thickness answers the purpose as well as any other the injurious effects kind.-J. E. V., Edinburgh. The best sheet zinc of the requisite the two permanent bar magnets, which stop [2046.]-GYMNASTICS.-The following works are [2066.1-ZINC PLATE FOR BATTERY-Had coil. It works exceedof lightning upon the recommended:-" Gymnastics," by Chiosso, price 1s. 6d., Walton and Maberley: "Course of Gymnastic would have found the practical part of it so easily ac- If" H. R. H." wishes, "G. Deku" put in practice the slight knowledge being well, much quicker Exercises," by Rolland, price 38. Gd., Oliver and Boyd; quired as hardly to need troubling the MECHANIC for I will send him a seems to be in possession of in regard to his query, he than the old system. "Roth's Movements or Exercises," price 18.; "Ling's information upon so simple a matter. Gymnastics," by Koth, price 2s. 6d., Groombridge-commercial sheet zinc will do, procurable from any keys used in these inBETA. The ordinary diagram of contact the acid solution with a piece of rag or a brush, pour manent bar magnets, B metal warehouse. After scouring the plate clean in upon it a little mercury, and by still continuing the needle which has north rubbing "G. Deku" will find the mercury spread itself and south poles as evenly over either side of the plate, making the amal- marked, CC coils, D gamation of the plate, if a matter of question, one of pinion of needle.-W. very little difficulty indeed.-H.

[2049.]-LANTERN LENS.-A single plano-convex lens would do, but the result would not satisfy you. Many cheap lanterns are nearly useless on this account; go to a little more expense to purchase a double condenser, or if you have a good fint planoconvex, get an optician to adjust another to it. Write to Cox, of Ludgate-hill, or any practical optician.C. WARD.

[2049.]-LANTERN LENS.-If "Lime Light wishes to have good results from his magic lantern, I would recommend him to use the double combination 3in. condenser.-J. E. V., Edinburgh.

[2053.)-BEECH.-Expose the wood to the presence of steam in a covered vessel for a few hours, then withdraw it and allow it to dry slowly. It should be under pressure of some degree, even if not more than

1 or 2lb. to the inch.-S. T.

over his plate by adding a little of the pure acid and
[2066.]-TO AMALGAMATE ZINC PLATE FOR
BATTERY.-G. Deku can make the mercury flow
then rubbing itoverwith a piece of tow or waste cotton,
then well washing it in plenty of water.
A. A. A.
If he cannot
get on, will he write to our ENGLISH MECHANIC ?-

this, multiply the square of half the diameter by
[2068.]-CONTENTS OF IRON PANS.- To find
355
and by the height. For instance, the first pan contains:

(2)

2 355
X
113

-ERNEST.

× 58 6in. =

11 x 11 x 355 x 11

2 x 2 x 113 x 2

113

=

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S." will look at my
RUS.-If
recipe for phospho-
[2081.]-PHOSPHO-
"M.
rus paste in No. 257,
page 588 [1760], he will
see that the phospho-
rus does not require
powdering. The proof
spirit will do that
quite sufficiently.-GITCHE MANITO.
-If "M. P. S." intro-
[2081.-PHOSPHORUS.
duces into a florence flask 1pt, phosphorus and 8pts.
of rectified spirit, and heats in hot water until the
phosphorus has melted, and then (inserting a well-
fitting cork) agitates briskly till cold, he will find the
phosphorus, on pouring off the S. V. R., sufficiently
fine for paste." See Beasley, p. 393, for an excellent
unfermenting paste.-A. P. S.

[2054-HYPOCHLORIC ACID.-Such an acid has not yet been discovered. The only oxygen acids of chlorine are:-Hypochlorous acid, HCIO; chlorous acid, HCIO,; chloric acid, acid, HCIO-ERNEST. HCIO; and perchloric [2055.]-COIN.-The piece, as per engraving, is a weight of the double crown of James 1st. There are 522 cub. ft. 118 cub. in. To measure the eubic contents others of various weights according to the denominaof a globe, multiply the cube of the diameter by 0 5236. tion of the gold coin, the unit 228., the crown 5s. 6d., the thistle crown 48. 43d., the half-crown 28. 9d. Isolidity of a sphere or globe multiply the cube of the [2068]-CONTENTS OF IRON PANS.-To find the issued in 1618. The weights were issued by Royal prohave standard weights of all the above, as also those diameter of the sphere by 5236, and the product will employed for the granitic paint is silicate of potash, clamation from the Royal mint, ard the chief officers a sphere.-To three times the square of the radius of it is admixed, and combine them in a durable manner, be the solidity. To find the solidity of the segment of which is supposed to harden the pigment with which in all cities, boroughs, and town corporate of England the base of the segment, add the square of the height, neither of which points are, so far as my experience and Wales were commanded to provide such weights and this sum multiplied by the height and 5236 will and scales as provided by the master of the mint, and all persons were forbidden to have or use any other

weights for the gold coins. Vide Ruding's, Annals of the Coinage," page 374.-D. T. BATTY, 9, Fennellstreet, Manchester.

[2055]-COIN OR COUNTER-In answer to Mr. Smith, the engraving represents a card counter. I have a similar one in my possession, with Vs. VID., instead of XIS. English coins were made of tin and copper, and now are of bronze, but brass ones were never struck.-HENRY W. HENFREY, M.N.S., Markham-house, Brighton,

[2057. ZINC PLANT.-Form a feeble solution of acetate of lead, suspend in it a piece of zinc and some brass wires, the latter represent the branches of the

tree.-ERNEST.

[blocks in formation]

goes, successfully attained.-S. T.

the blue colour he speaks of. If the stain is made
[2097.]-STAINING WOOD.-F. Dropprobably has
not given his work coats enough of stain to overcome
properly, this is the reason of its not being black
enough; he must do it several times, until the blue
colour is overcome. If this does not succeed, I will
give him, through our MECHANIC, a recipe that will
answer on his requiring it.-GILDER.

[2097.]-STAINING WOOD.-Drop a little sul
phuric acid into a small quantity of water, brush over
the wood and hold to the fire; this will produce a
fine black, which will receive a good polish. Or take
pt. of vinegar, 1oz. of dry lamp-black, 6oz. of iron
rust sifted; mix and let it stand for a week. Lay
3 or 4 coats of this on hot, and then rub with linseed
oil, and you will have a very deep black.-MINNEHAHA.
[2097.]-STAINING WOOD.-I think if F. Drop
probably die black.
were to give the wood a strong solution of salts of
leather, and might be so with wood.
tartar before applying the copperas, it would very
worth the trial.-AB INITIO.
This process is effective with
I think it is
[2102.]-VALVE.-I have used the annexed for s

three times the square of the radius C F, add the square FG, and of the depth FG; and this again by 5236, will give the sum multiplied by the depth and the product of the diathe product solidity of the bottom; to the sum of their squares; and this sum being mulmeters A B and C D, added tiplied by the depth E F and [2057.]-ZINC PLANT. again by 2618, will give made by "A Late Subscriber, E. S." by twisting a which, added to the solidity The zinc plant can be the solidity of A B CD, piece of wire round a lump of zinc and inserting one of the bottom, will give the contents of the pan teend in the cork of the bottle; then attach other pieces quired. To find the cubic contents of a globe multiply of wire to the zinc and twist them in any form he may the cube of the diameter by 5236, or the cube of the think proper; some put a little chins doll in between, and beads of various colours, which has a curious circumference by 016887.-J. LINTON. effect; then fill the bottle up with water so as to there is no stated amount of alcohol used for the purcover the zinc, and put a little sugar of lead in, and pose he speaks of-merely a few drops or so; but I [2069.] PHOTOGRAPHY. -In reply to "Lex,' let it stand perfectly still; the tree will begin to should advise him not to use it at all. With some grow. A pennyworth of sugar of lead may be samples of paper I have found that it tends to blister obtained at any chemist's-enough for 3 or 4; it will cause a white cloud, which clears off.-A. A. A. the paper, whilst with others I believe it almost pre[2057.)-ZINC PLANT.-This is easily prepared by lated spirit. That is best out of the operating room vents it. In no case, however, should I advise methysuspending a piece of granulated zinc in a strong so lution of acetate of lead. plates of lead will form upon the zinc, and increase the solution (after sensitising) into the bottle wherein model engine, which is a rough sketch of my own.In a short time beautiful being impure. My method of working is to pour back altogether, either the spirit of wine or the ether, both till the solution becomes exhausted.-BETA. is some kaolin, and the next time that I want to use it J.W.

LINK

HARCH 25, 1870.7

09.]-ALUM AND IRON TANKS.-If "AmaDyer" uses his iron tank to boil alum in, he will troy the tank, waste his alum, and spoil anything de immerses in it. Alum acts strongly on iron, and Bould be boiled either in lead-lined vessels or in read by means of a lead steam-pipe. Lead vessels are employed in alum works.-SIGMA.

(2121.-BOILER TAP.-"R. A." should unscrew the screw at the bottom of the plug; take out the plug, and grind it in with emery and oil until he sees it bright in every part: then screw it up again: this may stop the leaking. To get it out, put a lever in the bib, and unscrew. Fix a new tap with lead collars. red lead, and whitelead. -GILDER.

[blocks in formation]

tools required?-H. E. D.

[2147.)-BENNETT'S CHUCK.-I would be much obliged it " J. K. P." would explain Bennett's chuck for the benefit of myself and fellow readers of the ing the mandrel of the lathe still when using the Also if he would mention a way of keepdivision plate and index.-KENNINGTON AMATEUR.

MECHANIC.

[2148.] TALLOW. Will some brother reader
describe the best system of refining ships' grease into
tallow?-YOUNG BEGINNER.
[2149.]-SURVEYING.-Can any reader tell me
what book will give the best help to make surveys and
valuations of dwelling houses and land to be mort-
gaged to a building society ?-READER.

[2150.]-LIGHTING GAS LAMPS BY ELECTRI-
CITY-I have heard that a means has been dis-
covered of lighting street gas-lanips in a town
simultaneously with electricity. Can anyone tell me
if such a system is in operation, now, where and how
[2151.]-HARDENING MILL BILLS.-Will any
reader inform me how mill bills for dressing French
stones are hardened, and what is used for hardening ?-
T. MARSH.

[2152]-PAINT ON BICYCLES.-I wish one of your many subscribers would answer me these questions:How is paint put on bicycles?-is it common oil paint? and what gives it the glazy look? Is it some kind of varnish-A SUBSCRIBER.

-WOOL.-In reply to "J. F. F.," I can explain to him the following German names:-Holzlle, woodwool, is a wood reduced into powder, paper, waldwolle, forest wool, pine wool, or pine and employed as velvet powder for making flock Deedle wool, is a fibre obtained in Prussia, Holland, &c.; by treating the leaves of the Pinus sylvestris, &c., with a solution of carbonate of soda, this fibre is used for stuffing mattresses, making blankets, &c.; an etherous oil, an extract, and a soap are also obtained from this fabrication; flannel impregnated with this essential oil is preconised against rheumatism, &c. Kunstwolle, artificial wool, is the well known shoddy. The name of vegetable wool is also given to several fibres, viz,, the jute (Corchorus capsularis, textilis, &c.) of the linden order, or Tillace; the down of the lanero, corkwood (Ochroma lagopus); the down of the different kinds.of Eriodendrom; these two last belonging to the Sterculia order, &c.-BERNARDIN. [2136.) DIVIDING PLATE.-In answer to "Bier-it is done?-CANADIAN. lala," if your plate is a lathe pulley, and you have room for only, say six rows of holes, you will what I have on mine, viz., 360, 108, 100, 96, 84, 24 (the last for hard usage to save the others), as good numbers as you can have. If you want to do ornamental work by the double counting" of Captain Ash, then you must have 192 instead of 96. If you want large strong holes, and cannot get in 360, then 240, 192, 140, 135, 100, 72, are useful numbers. That was the last I made. Be fore that, I made one for my own use of 300 outside, [2153.]-VERTICAL SAW FRAME.-Would some then 11, 13, 14, 17, 19, all in one row, with 216, 140, 96, fellow reader give me some information on saw 34 inside of that. If your plate is flat from outside to frames? I have some large oak trees 2ft 8in. through, centre, you can get in many more in the diameter you and I intend to put a frame to cut them. Explain mention, and I consider one of 13 rows, that I once the different parts and what strength to make them made, complete enough for most practical purposes.it will have to cut 3ft. logs down to 1ft. 4in.-to take The one of the cutting engine, figured this week, has in any number of saws up to fourteen. Also the best 37 rows containing every number up to 100, and way of fixing the logs while being sawn-the logs are ranging as high as 366. Good gunmetal is much bet-mostly round, and will want good fixings. Give the ter than brass. I get mine at Bowen's, Dorrington: length of stroke. The weight of foundation required. street, Coldbath-square. Ask for best gunmetal. -J.T. W. have serious thoughts of taking the gunmetal pulley off my lathe, and putting on a cast-iron one, as the holes will last better. Division pegs, or "index pegs." are, in my opinion, always made wrong. Go to Wilkinson, by all means, if you want something firstclass, without being ruined. It is a chance if it did not come to him at last, if you took it anywhere else to get it done. Say your outside row is in. from edge, and distance between rows of rows you waut, and direct to me at Pitcairn's, Library, King's College-road, N.W., and I will write out a list for you.-J. K. P.

5

1

and state number 32,

[2137.)-PITCH PINE WOOD.-" Pinaster" had better get some of Stephens' wood stains. The cause of the wood looking opaque when stained is, the staining material has more body than it ought. Very good stains can be made of burnt sienna and Vandyke brown, in certain proportions, but Stephens' are more transparent. I see the "Welsh Shepherd" recommends one coat of oak varnish. Is he aware that it will not stand long out of doors, and some of it is the veriest rubbish possible. Stick to the boiled oil for the outside, two or three coats of it; never mind heating it; if heated look to your brushes, or you may get them burned up by the hot oil. "Pinaster may depend upon this information, as I have had experience for these last 24 years as a house decorator. All wood stains do not get darker in course of time; of that I am quite positive, and do not wish to mislead-GILDER.

[2138]-HARDENING MILL CHISELS.-I advise G. Doubleday to coat his mill chisels with finelypowdered pu siate of potash, make them red hot, and plung them into urine; then brighten and temper.-AS INITIO.

NOTES AND QUERIES.

(2139]-HARMONIUM.-Would some kind reader state how many rows of reeds I could have for an harmonium, the case of which is the size of a fiveoctave Alexandre's make? If some one would state how I could fit it up with two rows I should be much obliged, and, likewise, what kind of reeds, &c. would be required, as I am entirely ignorant how to proceed; but having made the case, bellows, &c., I want to finish it.-J. W.

[214]-POOR LAD'S QUERY.-Will some kind astronomical reader advise me? Having but very limited means, I thought of purchasing one of Wray's 24in. object glasses, price £2, but seeing in our last number that a 5in. specula would cost the same, I am rather in a fix which to have, and should esteem it a favour for a good opinion.-A POOR LAD.

(2141)-SPLITTING QUILLS.-How can I split quills in half-I have tried several means without success? Should the quills be soaked or softened ?— CROWQUILL.

2142-SOFTENING CAST IRON.-Can I soften cast iron before turning? I have a face-plate to turn; being so hard, the tool will not cut it.-G. B. K.

243-GLUE TO RESIST WATER.-Could you

sell me of a glue that will resist water, or of any com

Water? There is a firm in London, I think, who make

[2154.]-HARMONIUM-TO "ADEPT."- I am
trying to build a small harmonium with two rows of
reeds to represent four stops, and I should esteem it a
great favour if our good friend "An Adept" will
advise me which are the best reeds
to purchase for a small instrument,
also where I can purchase them, also

if the feeders will act as well on the
bottom board of case; if so, that will
save me much room? I also should
be much obliged if he will favour me
with a sketch of his silent feeder

to make a good paste or cement for clothing iron rollers?-T. SIMMS.

[2162.]-SEAMS OF MACINTOSH.-Can any fellow reader tell me what is used for joining the seams of a macintosh or waterproof coat?-G. W. D.

[2163.]-LEATHER BAG MAKING.-Would some one tell me how to make small leather cases-such cases being made of paper and covered with leather by gluing the leather on the paper cases-such as are now used by ladies and gentlemen ?-T. H. P. [2164.]-PHOTOZINCOGRAPHY.-Will some of your intelligent correspondents be kind enough to favour me with the titles of some of the best books on subject of photozincography and anastatic printing?-I desire to know the ins and outs" of the printing.-W. H.

the

[2165.]-WORKING MEN'S EXHIBITION.-Can exhibit an article of his own invention in the forthany correspondent say if any employer is eligible to coming Working Men's Exhibition, and say to whom to apply for particulars?-MORELIGHT.

[2166.]-MAGNET.-Can I make a magnet by battery power? Will Smee's battery do; how many cells? My magnet is 7in. x lin. x ĝin., horseshoe-shape, tempered steel.-J. GABELL.

[2167.]-LATIN.-Can any brother reader inform me if there is a system for self-teaching Latin; where I could obtain it, and what would be the cost?-A NEW SUBSCRIBER.

[2168.] DIMENSIONS OF MODEL STEAM ENGINE.-Will some brother reader give me the dimensions of fittings for a model steam enginecylinder 3in. stroke, 14in. bore? What size steam pipe should I require, and length of lever for safety valve ?-R. R.

[2169.]-PROBLEM.-Draw a line D E parallel 'to the base B C of a triangle ABC, so that DE is equal to the difference of B D and C E.-P. B. McG.

[2170.]-AN UNANSWERED QUERY.-Will some correspondent tell me how to blacken old copper coins? This query was asked some time since, but has not yet received any answer.-GITCHE MANITO.

[2171.]-BORING MODEL CANNON.-I beg to return my sincere thanks for the instruction furnished on the above subject. Being unable to make the halfround boring bit referred to, will either of my kind instructors be good enongh to inform me where I can obtain the same?-J. S.

1

[2172.] BINDER'S (CUTTING PRESS UNWill anyone oblige by ANSWERED QUERY giving a description of cutting press referred to by J. J. A.," query 1467? I can bind first-rate, but cannot cut with an ordinary knife. It would no doubt confer a boon on many of our readers.-MASCHIL. [2173.]-GAS'WORKS.-Will" Rotherwood" be so kind as give a few more particulars about his economical gas works in Reply 1731, p. 613, as to construction and operation in gas manufacture; also where the E. G. works are to be had?-JOHANNES.

[2174.]-MAGIC LANTERN AND MICROSCOPE.
-I have a magic lantern with 3 in. condensing lenses,
and should be glad to know what would be the cost of
a good microscope to attach to it-suitable for showing
animalculæ in water, &c. Would a powerful lens, to
burn camphorated paraffin, give a disc of light suffi-
an audience? Could the same instrument be so ad-
[2155.]-LACTARME OR MILK ALBUMEN.-justed as to be used in the daytime as a solar micro-
How can I make this in a dry state, so that it wil:
keep similar to the albumen of commerce, that is in
flakes very like shellac ?-LAC.

valve for bellows that was named in
January 14, as my valves make more noise that I like ciently large and clear to show microscopic objects to
to hear.-W. D.

[2156.J-ZINC ASHES.-What are zinc ashes, where can I purchase them, and what is the price per ton? ELDER KIN.

[2157.] AN INSTRUCTOR FOR PLATE-
LAYERS.-Will some of our brother correspondents
inform me where I can get a book that will instruct
me how to set out a raa.us of any dimension-say
from one chain to one mile, and the proper distance
from a pair of points to a crossing of say one in two
upwards? What I mean is the correct radius from
the points to any spread crossing for a permanent way,
I think there is a book as an instructor for plate-
layers?-UNLEARNED PLATELAYER.

[2158] ARTIFICIAL LEG. Will some kind
brother give me the drawings, and inform me how to
make an artificial leg below the knee, and what is the
best material to make it of?-W. R. E.
[2159.]—CLAMS.—Will any reader show me how to
construct a pair of clams for (splicing or jointing
leather-such as those used by roller coverers? A
diagram will greatly oblige.-T. SIMMS.

[2160.]-PRESSURE ON COLUMNS. Will any
brother subscriber tell me how many tons' pressure
four iron columns will bear standing upright as shown,

3

position for fastening wood together, so as to resist in plain figures ?-W, R. E.

[2161.]

3/2

PASTE FOR CLOTHING

SOLID

IRON

scope ?-FRAYER.

[2175.]-LIFTING POWER.-Has the wedge or the screw jack the most power in lifting ?-T. H. H.

[2176.]-BLAST FAN.-I would esteem it a favour if one or more of your readers would give me some information as to the construction and arrangement of a blast fan suitable for a smith's forge fire.-C. T. [2177.]-PROBLEM.-With a point in the perimeter of a given circle for a centre to describe another circle, an arc of which shall divide the given circle into two equal parts.-INDAGATOR.

size of a circular disc to be fixed on its centre in [2178.]-CIRCULAR DISC.-What must be the the boundary of a circular orifice 1ft. in diameter, so that exactly one-half the area of the orifice is covered by the disc ?-INDAGATOR.

[2179.]-GRINDING SPECULA.-Will steel, iron, and metal make a tool to grind and polish glass specula? For the purpose are the grooves cast or cut in the grinding tool? Can a glass speculum be ground, if firm, level and stationary? Is it possible to grind a speculum parabolic without first grinding it spherically?-ANDREW JOHNSON.

[2180.]-ENGINEERING IN GERMANY, &c.-Is there a mechanical or engineering school or college in Germany where pupils are instructed in practical as well as theoretical engineering, and where? Thanks to Mr. Biggs for his answer to query 1934, and may I ask him if he will kindly furnish me with a solution of the following, which appeared in the Science and Art Department examination papers a few years back? If an arc of a circle measure 50ft., while the radius is 18ft., what is the area of a sector whose base is the given arc ?-Y. P. W.

[2181.]-DERBY CEMENT.-Will some one obliga me with a recipe for Derby cement for mending jet, vulcanite, china, or glass ?-G. S. H.

[2182.]-CONSTRUCTING COILS.-I am about to make a coil, and intend to use about six miles of No. 36 copper wire covered with silk for the secondary, I want to know what length of No. 16 cotton-covered copper wire I should use for the primary, also about what number of sheets of tinfoil 1ft. square would go to the pound? I also want to know what length of spark I could get from the coil, also how many of the bichromate of potash bottle-batteries ought I to use? Is wire, covered with composition, better than silk or cotton-covered wire, or would wire, covered with cotton first and then with the composition, be still better? Is there any substitute for gutta percha tissue, and what kind of cotton or silk is used for covering the wire in shops where it is sold covered? These last three queries I have often seen asked, but

Mucks for carpet printers; these blocks have to be put ROLLERS.-Will any reader please to tell me how have never seen them answered. —NEMO.

[2183.] TAXIDERMY. - On application for the work mentioned by your correspondent, I find that it has been out of print for 20 years. Can anyone inform me if there is any other published, and who by?—

SOLD.

[2184.)-SULPHATE OF LEAD BATTERY.-I will feel obliged to any of your readers who will be so good as describe how these batteries are made. I understand Moseley's patent battery consists of copper cups tinned, and fixed on a central wire. Is it actually necessary to have the cups so tinned? and is a porous cell requisite? Would a solution of sulphate of lead not do to charge Smee's cells with? "Sigma" has promised a description of all batteries now known or used, but it may be some time before his papers bring him on to that part of the subject, and in the meantime many of your readers as well as myself may be at a standstill for want of the information.-FRONTI

NULLA FIDES.

to

[2185]-MILDEW ON ENGRAVINGS. I shall feel much obliged if one of your correspondents will inform me how to remove mildew from picture prints, and how to prevent it.-CONSTANT READER. [2186.] - BAROMETER TUBES. Thanks "Jonath" for his information on the safety valve. I have some barometer tubes (new ones), and in laying by they have got covered with a film inside that makes the mercury look muddy when it is put in. Can anyone tell me the best way to clean them?-COMPENSA

TION.

[2187.]-NAPHTHA AND GAS TAR.-Would any brother subscriber give instructions for making naphtha and anything else that can be made from gas tar, with a description of vessels, &c., required for the same? About 80 gallons of tar is as much as I intend to use for that purpose weekly, which will, perhaps, give an idea of the sizes of what will be required.J. H. M.

[2188.]-ORNAMENTAL WOOD AND METAL CUTTING MACHINE

AND VELOCIPEDE. Having for some time seen advertised in our paper Cunningham's fret-saw, drilling apparatus, and kinograph, I should like to have the opinions of a few of our subscribers who may have tried them as to whether they are useful machines, well made, of good metal, worth their price, and, in short, all they profess to be. I should also like the opinion of some of our velocipedists if in every case a driving-wheel above 36in. ceases to be an advantage. I have an ordinary 36in. and 33in. bicycle, but I want to get nearer the ground, and I think of reversing it, so bringing the small wheel to the front and making it the guiding wheel, and putting the wheels farther apart and driving it by a crank working in a bearing between the wheels, and communicating with the driving wheel (the hind wheel) by a connecting rod as outside a locomotive; or with a pedal working like the elbow joint of a bell-pull and connected as before: shall I use my old wheels, or have the driving-wheel larger-say eft., and, perhaps, the front wheel smaller -say 2ft., and which driving-gear shall I use?—GIM

CRACK.

[2189.]-CIRCULAR RAIL.-Can any reader inform me how to make a circular rail for a model locomotive? It must be constructed on a framing of some sort, so that I can lay it on the floor of a room without injuring the curpet, &c.-F. G. C.

[2190.]-THE ORGAN.-Can any brother reader tell me the way in which an octave coupler is made? also how a composition pedal is connected to the stops? A drawing of each will oblige.-ORGANINE.

[2191.]-TURRET CLOCK.-Would Mr. Maddison kindly inform me what advantage he gets in the use of cast iron wheels in his clock instead of brass-most generally used? I never saw one erected successfully with iron wheels. I should think that an iron wheel working it a pinion of iron or steel would work harshly together, and also be liable to stop through rust collecting between wheel and pinion.-TINTAC.

[2192]-SULPHATE OF AMMONIA.-Would Mr. G. Davis, or some other among your talented correspondents, inform me of the most improved and simplest way for finding the degree of strength of sulphate of ammonia ?-Basin.

power

[2193.]-FINE CHARCOAL.-Can any subscriber inform me where I may obtain fine prepared charcoal for rubbing down silvered circles, &c. ?-it is generally in short square sticks.-TERMUS. [2194]-INTENSITY COIL.-Can any fellow reader inform me how to make a small intensity coil ful enough to fire gunpowder?-COIL. [2195.]-SMOKELESS LAMPS.-Would Henry W. Reveley, Reading, who sends a sectional drawing of smokeless lamps without a chimney, in your journal of Jan. 21, 1870, kindly furnish particulars as to construction, length of cone and hollow globe, and how the wick is raised or lowered?-PRACTICAL.

[2196.]-NAMES OF PUBLISHERS.-Is there a book published entitled "Annals of the Wars of England?" and if so, please name the publisher and price? if not, I should like to know the name of the publisher and the price of the " Annals of the Wars of Europe." What would be the most simple work on bell-ringing, the publisher, and price?-H. G. REDDITCH.

[2197.]-TO GEORGE E. DAVIS-I wish, through the medium of the ENGLISH MECHANIC, to thank G. E. Davis for the information he has so freely given, and to request him to give me further information on the following points:-1. How to estimate sulphuric acid in salt cake? 2. How to separate barium from strontium? 3. How to estimate chlorine by volumetric analysis? 4. How to analyse roughly a sample of patent manure-such as Standen's? 5. How to estimate the ammonia in a sample of manure ?DISCIPULUS.

[2198.]-BORATE OF BARYTAS.-Could any correspondent give me a simple plan how to make borate of barytas ?-HANLEY.

[2199]-TELESCOPES.-Will "A. R. T.," p. 614, or any other of your correspondents answer me any or all the following questions:-1. What is the probate reason that I cannot get a good view of the sun's spots with one of Solomon's £5 telescopes? 2. What

will be the probable cost of putting a rack on the focussing s'ide of the above telescope? 3. What will be the best and cheapest way of mounting one of Solomon's £5 telescopes on a stand, the legs to be made shorter when not in use? Perhaps "Pollux," on p. 604, will be able to give some information about a suitable stand for a working man's telescope, as he seems to know what they have to put up with when they cannot afford the more elaborate and costly workmanship of an Equatoreal stand, viz., the primitive and uncomplicated mechanism of a brick wall, and the elevation, depression, and sideral motion of the instru ment as to be performed by muscular power?-H. F. Will any of our friends, having experience in such matters, kindly inform me what style and size of engine and boiler is best calculated for driving a launch 36ft. long by 9ft. broad, with number of blades, pitch of screw, and probable cost ?-SOLICITOR. [2201]-STEAM ROARER-Will some kind reader inform me how to make a cheap and simple steam roarer to act in place of a bell for a mill? I should also like to know if it is obliged to be made of brass? There was a plan of a steam whistle in the ENGLISH MECHANIC a short time back, but the drawing was

[2200.]-ENGINE AND BOILER FOR LAUNCH.

very small. I failed in making one off it that would act, so I wish to have the plan and dimensions of one of those sort called a roarer, which are so much used now for works.-YOUNG ENGINEER.

(2202.]-WHEEL SKATES.-Will some brother reader kindly inform me the best plan for making wheel skates?-C. FRANCIS.

[2203]-FLOUR DRESSING MACHINE.-I am trying to fit up a small machine so that I can run down a few sacks of seconds flour whenever my other machine is broken down, and occasionally a few grists. I have made a 12in. cylinder which will take three sheets of flour wire and one of sharp wire? What number of wire ought I to use, and how many brushes, and what fall ought the cylinder to have ?-A COUNTRY MILLER.

[2204.-PROBLEM.-The diameter of the plate of placed upon it; what will be the height of water in the a hydrostatic bellows is 12in., a weight of 250lb. is pipe?-W. B. S.

[2205.]-PROBLEM.-What is the atmospheric pressure when the barometer stands at 30in. ?-W. B. 'S. [2206.]-CERAMIC MANUFACTURE.-Thanks to "Beta" and H. B. Miller for their information. On inquiring, however, at Barth's and Quariteh's, I find that instead of 208., 289., &c., Brongniart's book is 568. Are there different editions at different prices? It is not needful that the works sought should be in French a good practical English or French book at a moderate charge, especially if treating on the preparation of colours for painting, and printing, is what I require.-IOTA.

[2207.)-CRICKET BATS.-How are cricket bats made? I have tried my hand at one several times and failed?-A SUBSCRIBER IN CANADA.

[2208.)-REFINING BEESWAX-Some time ago "Feu Follet," in reply to "Pulp Maker," offered to detail the process of refining with chlorine: would he please do so, as I wish to try my hand at it?-A COLOURMAN.

[2209.]-OVERLAND ROUTE. Will "Selwyn" explain why, if the Overland route ria Marseilles is also via Southampton, the Postal Guide" makes the distinction of the routes for letters, thus-India ria Marseilles 18., via Southampton 9d.? How do the 9d. cnes go?-IOTA.

[2210.]-BAR MICROMETER-Might I ask Mr. Proctor or some obliging correspondent to be kind enough to favour myself and your innumerable astronomical readers with a drawing or description of a bar micrometer and its field of view, and explain its uses? What is the difference in use between it and a ring micrometer ?—IOTA.

[2211.]—OBJECT GLASSES.- Referring to Mr. Purkiss's letter on t's subject in the ENGLISH MECHANIC for Marcl. 4th. might I ask him to be kind enough to say in what year he knows y Andromeda to have been divided by Mr. Buckingham's instrument with a power 2? and also if he can inform me how many seconds apart they then were, and how many at the present time?-IOTA.

[2212]-SPIRAL SPRING.-Is the spiral spring reliable as used for steam pressure gauges? I presume that steel springs are only useful within narrow limits-say a range of 40lb. or 50lb. What I want is an extremely accurate means of registering pressure, extremes I have stated. I suppose this might be done increasing by a pound at a time, between the two by communicating the pressure to a hand travelling round a well-divided dial, but my difficulty is in what yard would seem the best way of applying the weight way to communicate it? The principle of the steelfor the division of the dial. Can anyone suggest a better?-F. Q. Q.

[2213.]-STANWAY'S VELOCIPEDE.-I hope Mr. Stanway will answer a few questions respecting his velocipede-a description of which is given in the MECHANIC for March 4th. Does he propel his velocipede by means of his feet as well as his hands? and how does he manage to steer it, as the handle appears to be fixed between the levers, in consequence, there would not be room to get it round a sharp curve? Is it steered with the feet or hands? What is the distance between the front wheels? Please to describe the method of steering, &c.; also what is the price of such a velocipede, and the name and residence of the maker? If he will describe how it is constructed in front as well he will much oblige.-AN ADMIRER OF

THE VELOCIPEDE.

[2214.]-CANOE.-I am about to build a canoe. Would some reader kindly let me know where I can obtain a book containing practical information on the subject ?-C. D. RICHARDSON.

[2215.]-STAMPING SHEET BRASS.-Can any reader tell me how to give brass the appearance of bronze, and where I can get dies made for stamping sheet brass ?-TYNO.

[2216.]-CARRIAGE PAINTING.-Would someone kindly inform me how the paint for carriage work

is mixed? and also how to mix the paint for striping? -YOUNG PAINTER.

[2217.]-WHAMPOOM MONEY. - Our ENGLISH MECHANIC has spoken several times of Cowrie money or shell money. I should feel obliged for some information on the Whampooms of North America PIONEER.

[2218]-GEOMETRY. Is there any geometrical means for proving the following theorem ?-Having three circles on a plane, and drawing tangents common to two, those common tangents have their intersections on the same straight line.-X. X.

[2219.]-SILICIOUS GALENA.-Could some reader give me a few details on the modern methods of reducing silicious galena, also on the substitutes for nitro-glycerine (blasting purposes)?-FEU FOLLET. [2220.]-SOLDERING.-I want to solder a 2in. cast

iron pipe to a 2in. lead pipe. I find a difficulty in tinning the cast iron pipe. Can any friend inform

me how I can do it ?-G. D.

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[2223.]-ENGRAVING ON SLATE.-What kind of knife or graver is employed to engrave the lines and figures on a slate sun dial?-F.R.A.S.

[2224.]—BOILER-Thanks to "Vivas Sperandum ” for his kind answer to my query, but will be be kind enough to give me a few more particulars? 1. Could I not put in the feed cistern at once without pipe and funuel as shown? 2. What would be the quantity for 50-horse power boiler per week (754 hours); pressure, 45lb.? The water is very much impregnated with lime; scale very hard-like porcelain almost. 3. Has my brother reader ever tried carraqun in a boiler much incrusted, for my boiler is very intricate ?-UNE IN A FIX.

(2225.]—VACUUM IN CYLINDER. — Will' some on leaving the cylinder of a high-pressure engine brother reader kindly inform me if the exhaust steam causes a partial vacuum, or has the piston to be forced against the full atmospheric pressure, or 15lb. on the square inch ?-VACANT HEAD.

[2226.]-TINCTURE OF IRON.-How is the tincture of iron used in medicine made, and what complaints is it supposed to cure?-VACANT HEAD.

[2227.]-LIFE BELT.-Where can I get or how could I make a life belt for boating purposes?—AVA

LONENSIS.

[2228]-ADDRESSES WANTED.-Will any kind English brother reader give the full addresses of some of the most important coal mines in Great Britain?-A FOREIGN CORRESPONDENT.

[2229-WORKS ON CHINA GRASS.-I want some good works on China grass-either English, French, or German, &c. If a brother correspondent will answer my query, stating purchaser and price, he will much oblige.-A MELLIST.

[2230.1-REMOVING FLY SPOTS.-I have a very fine old engraving, but, unhappily, quite covered with fly spots. How can I remove them? I have tried several ways, but failed.-PERA Y NO PERRA.

[2231]-ENCKE'S COMET.-Will you please be good enough to ask "Omicron" to explain what is meant by solving an equation by the method of least squares-an expression that occurs in his account of Encke's comet ?-T. WAGHORN.

[2232.]-PROBLEM.-Can any reader favour me with a solution of the following problem from Todhunter's "Smaller Trigonometry," chapter X. :-The hypothenuse A B of a right-angled triangle is divided at D, so that A D is to BD as CB is to CA. Show that tan ACD — CD= 22

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-J. M. SMALL. [2233.] STAINED GLASS. Will Mr. Josepb Leicester or some other able correspondent inform me how ornamental church windows are painted and stained, as I have a little knowledge of some part, except ingredients that are used? I know there is a reddish brown colour painted on the glass for opaque and shading purposes called flux-it is mixed with turpentine. I want to know what it is composed of; when it is burnt in a kiln it is very hard, and cannot be scraped off. I want also to know what ingredients are used to stain plain glass in parts where wauted, such as yellow, blue, &c. For windows, as above, I have seen glass when taken out of the kiln with a red colour or deposit on them, and when cleaned off leave a beantiful clear yellow stain on the glass-according to the design painted on.-GUSTAVO KNOX.

[2234.]—TO “JUPITER."—Will "Jupiter" kindly tell me where he procured his 3in. refracting telescope of which he writes in evident praise in the last issue of the ENGLISH MECHANIC, and what he gave for it? Will he give me his idea of the apparent diameter of Jupiter as seen by him with a power of 75? I have this moment completed some observations with a Gregorian of 4in. aperture, and a power of about 10. Jupiter certainly did not appear to me to be more than in. in diameter, nor could I detect more than a mere suspicion of the " belts," but then it was not a good night. Will "Jupiter" kindly tell me the highest power his object glass will advantageously bear, and the apparent diameter of the planet "Jupiter" has seen with highest power? This will supply me with a point of departure from which I may deduce for myself other measurements.-FUIMUS. [2235.]-HOSIERY YARN.-How can I double and twist two threads of hosiery yarn from one to four per inch ?-TINKER.

[2236.]-DIRTY CEILING.-Can anyone tell mo why the joists show through dirty ceilings, ie, whereever a joist is the ceiling is much cleaner than the space between them, which gives it a ribbed appearance ?-MINNEHAHA (GITCHE MANITO.)

[2237.-SALERATUS.-What is it ?-A. P. S. [2238.]-FORMULA FOR CALCULATING POWER OF SPIRAL SPRINGS.-Would any reader kin y

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