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bar I wish some were more easily pronounceable When one is about it, it is as easy to write under a seat and comprehensible name, such as 'Sigma 'or 'Beta,' as Terset Denroy,' or Ab-oth-Yate.***

THE MOON.-Cornelius Varley says: "Our side of the moon is 1000 miles nearer than its centre, so needs to move quicker, but cannot, so it falls that little towards the earth, whilst the outer side, being 1000 miles farther than the centre, would move slower, 80 the moon has to drag it along, and thereby gives it some projectile force outwards, and thus the moon becomes somewhat oval; the near side pulling towards the earth, whilst the farther side is pulling outwards, makes it keep one face towards us. But the moon, as an enormous fly-wheel, cannot alter its rate sud

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denly, so it keeps an equal or uniform rotation on its own axis during the very unequal speeds round its orbit almost as 5 to 4 from Perigee to Apogee; and this discrepancy in the two motions is the cause of libration; for when the moon is farthest it passes us very slowly, though its own rotation continues uniform, so it shows us more on one side. Then when the moon is nearest it passes quickly, and shows us more on the other side. Thus, the moon's very uniform rotation on its own axis, and very unequal speed in its orbit, most besutifully shows the two separate motions. But this same action that so slightly elongates the moon is shown with the greatest intensity in the rings of Saturn; for they are so near their primary as to be not only stretched out flat, but have been obliged to separate into several rings by the differing speeds due to their respective distances."

TYPOGRAPHICAL ERROR.-"Ab Initio" writes: -There is a sad error at page 23, under the heading "Interesting Facts." An acre is said to be 1840 yards square. I think it should be 69 yards 1ft. Shin."

THE TRANSIT INSTRUMENT.-"R. E. T." says:- Apropos to the very able and interesting article on the Transit instrument and its use, in this week's number of the ENGLISH MECHANIC, will you allow me to inform your readers that the gentleman who was the originator of cheap telescopes is now engaged in an endeavour to construct a cheap transit instrument for working men, which, while it will not aspire to the accuracy of the most expensive instruments, will enable a person to get correct mean time to within 5 or 10 seconds? When complete, it will be brought under public notice through your journal."

SPLICING LEATHER BELTS.-"R.T.S." says:"The following cement requires only to be tried, and it will come into general use. If properly done, it is quite as strong as the solid leather:-Dissolve Nelson's opaque gelatine in acetic acid by adding as much of the acid, and no more, as will dissolve the gelatine by putting it on a warm place on an oven or boiler. The splices should be made nice and thin, pasted with the cement, put together, and cramped between two pieces of wood, or, if a large number of joints are to be made at one time, lay the belt at full length on the floor, paste each splice separately, and rub it on the top with a piece of thin wood, squeezing as much of the cement from between the joints as possible, and left overnight until properly Bet."

REPLIES TO QUERIES.

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[1611.]-APPARENT PARADOX.-"U.B." is dissatisfied with Quilosa." "Pneuma" has coufused division with multiplication, and U. B." rejects my, explanation because "J. B." says nothing is not equal to nothing. I must remind "J. B." and "U. B." that the base of the operation is the assumption that a does equal b. This should satisfy "U. B."-EXCELSIOR. [1886.]-MEASURING PATTERNS.-The method given by "C. J. B.," for finding the cubic contents of patterns, is evidently correct, but the same method would not always do for finding the cubic contents of the casting from the pattern (which, I presume, is what Green wants). Very often the interior, or any part, has to be taken out by means of a core-a common pipe, for instance; the pattern is generally made solid, and th interior is formed by a core. If the pattern is solid, the way to find the contents of the castings is this: Find the quantity of water displaced by the pattern and the core separately, and subtract the latter from the former, and the remainder will be the cubic contents of the casting. When the casting is large. the pattern is not made solid for obvious reasous; sometimes the mould is built up with bricks and loam. and swept up to the required shape by a few boards, and no pattern is required at all. In all cases, when the eastings are large, the contents must be found by calculation, the rules for which are to be found in any work on mensuration-SCIRE VOLO. (2014.) TRICYCLE. -I apply the motive power on donble 5-in. crank axle direct from the shoulder, without the aid of levers of any kind.-W. P. J. P. [2027.]-INDICATORS FOR ELECTRIC BELLS. R. T." understands the electrical action but not the mechanical. The adjusting weight is so balanced that a current through either magnet attacks the armature, and leaves the same in the attracted position after the contact is broken. The kitchen push, therefore, is tied to throw back the card by making contact.-CELSIOR.

[2033.]-CEANING SLIPPERS. "Inquirer" wants to know how to clean his slippers. Let him dissolve oz. of oxalic acid in half a pint of warm This will fetel: the dirt and grease off, and when nearly water, and when cold, sponge his slippers over with it. dry rub a little olive oil in; this will soften them and improve them, no doubt, to his liking.-UNLEARNED MAN.

[2085.] SOLVENT FOR MARINE GLUE.Mineral naphtha is the proper solvent for this substance.-W. W.

[2085]-SOLVENT FOR MARINE GLUE.-Has our friend J. S." tried heat? Marlue glue is made liquid enough when held in a flame.-IOTA.

[2090] and [21381-HARDENING MILL BILLS.The VIII. and IX. vols. of the ENGLISH MECHANIC contain practical recipes which have been amply tested, and acknowledged to be of great service. difference among millers in handling the mill bill, as It strikes me very forcibly that there is the same seen a stone-dresser cast aside one bill after another, as between one writer in holding the steel pen. I have not fit for use, when the same tools, in the hands of his comrade, dressed the stone properly. Before diamond dressing machines came in, millers were proud of their good work, and in a visit to a mill lately, where, in times gone by, I have dressed many a pair of stones, I was deeply impressed with the dependence placed by the present race of millers on improved machinery. ONE OF THE OLD SCHOOL.

[2091.]-PENDULUM.- A B = y = 41" A x B = 30

ABBA = 88° 30' log. A Blog. sin. 30+ log 41 log. sin. 88° 30' ='3817329

AB = log. 3317329 = 21465"

BREAD MAKING.-"A. B." writes:-" T. Estée asks for a good method of making yeast for home use. He is welcome to the following, which I had from a cook in a first rate family in London, who never used baker's bread:-Take 2oz. of hops as fresh as possible, with 3qts. of water, and boil two hours; let it stand about five minutes after taking off the fire; then pour through a sieve over 1qt. of malt; let stand until only warm-not cold; then put in 1pt. of patent yeast, or some of the same sort previously made, which is far better; let it stand all night to work, then bottle off, and it will keep good for two months. It is best not to let yourself run entirely out of the last brew, as some of it is required to mix with the new yeast to Or if "Pendulum " mean that the angle A y = 30

work it properly; if you have none, a pint of patent yeast from the baker's will do. If T. Estee tries this, I should be glad to hear with what success."

..AB = 6°

...BA A B = 87° ... AB=4-2915", Answer. [2091.]-PENDULUM-The distance, straight, from point to point, is 2-146454in. The distance along the curve traversed by the point of the pendulum is 2-14675497095302in.-MAIDEN NEWTON.

TO MR. HENRY D. BARNES." The Secretary-BLUE RUIN. of the Museum of Fire Arms, Peckham-rye, presents his compliments, through the Editor, to Mr. Barnes, and begs to know if he would have any objection to exiribit a model of his Invention for preventing gun accidents, in this museum, for the benefit of its members, who are all shooting men "?"

ELECTRO-DEPOSITED IRON.-Mr. W. Roberts, the chemist of the Mint, availing himself of Jacobi's process, has achieved something surprising with his specimens of electro-deposited iron. The Bource of the deposit is a solution of sulphate of iron and sulphate of magnesia; the rate of deposit is about the same as with copper, and the iron thus obtained is so hard that it will scratch glass, and has been found eminently useful for cliches and plates for printing purposes. Among Mr. Roberts's specimens, exhibited at the Royal Society, were bank-wote plates, medallions, mouldings, and raised work of various kinds; and one plate had been converted into steel by a process which was not revealed It is easy to foresee that so successful a method of depositing fron of exceeding hardness may be largely employed in giving a surface to rough iron castings.

=

[2094.]-SOLID CONTENT OF CYLINDRICAL FIGURE.- 2', h = 10'. 4πr3

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3

= 31416 x 22 x 10 + =125-664 + 33:5104 Answer = 159 1744 cubic feet.-BLUE RUIN. [2094.]-CONTENTS OF CYLINDER.-I can answer only the last part. The contents of a cylinder are obtained thus:-with hemispherical ends Diam. 3 x 5236 gives cubic contents of the two ends. Then diameter 2 x 7854 x total length, less the diam. = the contents of the cylindrical part, the sum of the two products being the total cubic contents. In the case in point, 4ft. 3 x 5236 31.51 cubic feet; and 4ft. 2 x 7854 x (10-4) = 75.39 cubic feet. Total capacity 108-9 cubic feet.-Q. Q. R.

[2091.]-PENDULUM.-The swing of a pendulum 41in. in extreme length, for 3 degrees, is found thusვი

x circumference of circle

360° 82in. diameter

inches. (= 2.146 {=2} full. or 715 of an inch for each degree of swing.-Q. Q. R. [2007]-STAINING WOOD.-If F. Drop will put with vinegar, the mixture, after standing some hours some iron or steel filings in a 2oz. bottle and fill up with occasional shaking, will stain wood a jet black if the wood has been previously washed, once or twice, with a strong decoction of logwood chips, which should be boiled and applied warm-SCRUTATOR.

[2097.]-STAINING WOOD.-I may say that a jet black stain for wood is sulphuric acid (oil of vitriol), with which the wood is to be brushed over, and held close to a fire. The acid really carbonises the wood to a slight extent. Experiment will best show whether the acid requires to be diluted or not. It is better not to use it stronger than necessary, and the woodwork should be well washed afterwards, to remove all traces of acid.-Q. Q. R.

think leather washers would probably suit "Scotch [2098]-DISCONNECTING STEAM PIPES.-I

Mechanic "-IOTA.

[2098]-DISCONNECTING STEAM PIPES.- If "Scotch Mechanic" would whiten one side of his india-rubber washer with whiting when making his joints, he might disconnect them many times without breaking them. I have used india-rubber washers for manhole joints on steam boilers for years and by whitening them they have lasted for years, being taken off every few weeks for cleaning.-B. W.

[2101.]-DARK TENT.-An amateur photographie friend of mine has used successfully for several years a dark tent, composed of three or four thicknesses of black and yellow calico, which I understand quite shuts out all hurtful light. Will not this suit G. R. F."? It is light and durable, and when worn out costs but little for renewal.-Q Q. R.

[2106.]-STEAM WHISTLE.-I send a sketch of a section of a steam whistle, which is formed of either brass or bell-metal. A is cast hollow with a flange,

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and bolted on the engine at Cc. F is a cock placed into it working with the liandte K, and a screw M, to keep it tight. The cup G is screwed on to the tem A, and leaving a narrow passage, E E, all round. The piece G is hollow, having holes L L in its sides, and a pillar H standing on its centre, on which is screwed the bell O O, the thin edge of which is brought just over the opening E, and half an inch above it. On opening the cock F, the steam enters the cup N, through the holes L, which causes the shrill screaming sound. Holes M M are made at the top of the bell O, to allow the steam to pass out, and improves the sound. The sounds of the whistle are regulated from shrill to hoarse by the size of the concentric part where the steam escapes, depth of bell, and their distance. -F. B. KNOX.

[2111.]-TESTING MILK.-The lactometer sold in the shops at Is., with directions for use, is the most ready way of ascertaining the quantity of cream present; the hydrometer for determining the density, or relative richness in caseine matter, and dilution with water.-PATER.

tioner," by Cox, Longman, and Co., 88.; Confee[2112]-CONFECTIONERY.-"Practical Confectionery in " Industrial Library," Houlston, 18. 6d. Every description of lozenge, drop, candy, &c., is to be found in Cooley's "Cyclop. of Practical Recipes," published by Longman and Co., price 288.-A LOVER OF BOOKS.

(2114] GUTTA PERCHA STRAPS.-I have used. many straps and bands, for which, when running at high speeds, the best lubricant is cold water. Whenever they became stiff, as they will in cold weather, or when out of use for a time, I soaked them in warm water, and brushed them with a stiff brush.-H. B. M. [2116]-WATER POWER.-200 gallons per min. falling 30ft. produces 11 h. p., but as about one-third of this would be absorbed in overcoming the inertia of the wheel and gearing, the wheel being of good construction, with properly ventilated buckets, there would remain for useful work 7 horse power. But a turbine would be preferable to a whee! under the circumstances stated.-C. S.

[2117.]-CEMENT FOR IRON ROOM.-"T. S. H." should put strips of well tarred felt between the iron sheets, where they overlap, or he may caulk the joints with oakum, and then tar it all well, and throw on sand.-IOTA.

[2121-BOILER TAP.-If the plug of the tap is so made as to be removable by taking out the screw underneath, take it out, and Laving put some oil and flour emery on the part that works in the tap, re-insert it, and turn it about, frequently withdrawing it, until the surface is ground bright, and the plug perfectly fits the tap. Then wipe off carefully all the emery, and smear the plug with tallow. On re-inserting it, it will be found that owing to its diameter being reduced by the grinding, it will go through the tap too far for the washer to get a bearing on the under part of the tap; the square on which this fits must therefore be filed as far up as is found to be Lecessary, as the hole in which the screw works drilled and tapped deeper. If a new tap is wished to be put in, there is no cementing required, but some white lead well worked into a washer of felt, which is put on the screwed end of the tap after it is inserted into the hole, and the screw nut is then tightly screwed down on it. To prevent a tank from leaking, let nothing but rain water be put into the boiler.— W. W.

[224]-EARTH CLOSETS.-If "R. M." can manage to get a drain from the bottom of the vault to carry off the liquid matter, he will find his alteration a successful one. A second pan connected to the drain, when the place is used only as a urinal, will make the ob better still-SCRIBBLER.

2124-EARTH CLOSETS.-I believe the same difficulty was experienced at the gaol at Reading, Berks, and that a remedy was found. If the Governor there were applied to, he might furnish the required information; and if "R. M." by this means, finds what he wants, it would be useful to others, if he would send it for insertion in the ENGLISH MECHANIC. -C. 8.

(2126.)-JOINING WIRE-If “E. H. B." wishes to splice copper wire, he has only to twist the ends together; if strong iron wire, each end should be turned up and laid over one another for a length of about 2in., and then wrapped tightly with copper or good iron wire.-IOTA.

[2128.)-ASSAYING.-The process, as performed at the Royal Mint and Goldsmith's Hall, occupies five closely printed pages in Ure's Dictionary of Arts, Manufactures, and Mines." There are numerous illustrations of the apparatus, and tables, to which it would be better to refer than attempt a clumsy abridgment of so lucid an account.-A LOVER OF BOOKS.

[2131.] PUMPS." Plumber" seems to have got somebody else's work. However, if he has it and has to make the best of it, perhaps this reply may be of service to him. From 40 to 50 (call it 45) gallons of water per minute falling 8ft. will produce a tenth of a horse power, but as the friction of the turbine and gear will absorb about one-third of the power expended, there will remain but the fifteenth part of a horse power for useful work. A turbine might be made to utilise this, but it would be a mere toy machine. Supposing it made, however, it would deliver through the pipe described, and to the height named, 3 gallons of water per minute. This quantity is so small as to be practically useless, and therefore some other means of supply should be advised.-C. S.

[2131.]-PUMPS.-The quantity of water available, say 50 gallons per minute, being so small, and the fall only 8ft, would it not be well to inquire whether, instead of a small turbine, a not prove more efficient, thus dispensing with the mawater ram would chinery of pumps, &c.? I have seen them employed for the purpose of supplying water to houses in the country, where a small fall of water was at hand, one great advantage being that the action is continuous, requiring little or no attention. There are one or more firms in London who pay great attention to this class of water engine.-H. В. M.

[2135.]-WASHING BLUE.-Mix finely-powdered Indigo with starch paste, and make it into cakes of the required size and form.-GUILLAUME.

[2135.]-POWDER BLUE.-" Roasted cobalt ore and carbonate of potassia, of each one part; siliceous sand three parts; fuse together, cool and powder Used for bluing the starch in getting up linen."Cooley.-H. B. M.

[2166]-MAGNET.-One or two pairs of Smee's
elements, quarts, in moderate action, will make your
magnet permanent if you wind plenty of insulated
wire round it.-BRUIN.

[2167.]—LATIN.—A New Subscriber" will find
Beard's Lessons" in the Popular Educator all that
week; but he might possibly obtain one of the pre-
be requires. The numbers are published at 14d. a
vious editions second-hand. If A New Subscriber
knows the rudiments, he might find the Popular Edu-
cator lessons too full at least, that is my opinion,
to get White's Valpy's Delectus" and "Chambers |
Under those circumstances, I would recommend him
Grammar (the best, bar none, at the price).
are to be found on second-hand bo k-stalls; the first
Both
38. 6d.-SAUL RYMEA.
at 6d.; Chambers' Grammar about 1s. 6d. ; full price

D

A

[2169.]-PROBLEM-Draw a line D E parallel to
the base B C of a triangle
A B C, so that D E is equal to
OBD-CE. Solution: Con-
struct interior and exterior
bisectrices, and through their
intersection a parallel to the
base: the isosceles triangles
EO BDCE.
BDO and CEO give DE=
Remark: For two in-
terior bisectrices we have the parallel = the sum
of the segments.-BERNARDIN.

B-
DO

[2170]-UNANSWERED QUERY-Old coins are generally black enough, but if you cover them with fine plumbago powder, heat moderately, and rub briskly, you may make them as black as you like.BRUIN.

[2172.]—BINDER'S CUTTING PRESS-I should cutting press, but it would only be wasting our Editor's be most happy to give Maschil" a description of a space, for the tools and wood would be more expensive than buying the articles properly made. A new cutting press, plough, and pin can be obtained for 328.; a secondhand apparatus for le-s.-AB INITIO.

[2175.]-LIFTING POWER.-The screw and the wedge are on the same mechanical principle-that of equal and the external force applied equal, they should the inclined plane; and therefore, if the angles are raise the same weight. Which it may be best to use must depend on each particular case.-BRUIN.

common clam shell (Venus mercenaria), the white of
the columella of various shells (Strombus gigas, &c.). A
piece being split off, a hole was drilled in it, and the
form, which was that of the beads known as "bugles,"
inch long, generally disposed in alternate layers of
was produced by friction; they were about half an
white and blue, and valued about two American cents
for three blue beads or six white. A fathom of white
was worth about 2 dollars; they were of less value at
was used in traffic, in treaties, and as a token of friend-
the time of the War of Independence. The wampum
ship or alliance. Wampum belts also constituted re-
Mr. J. K. Lord brought froin Vancouver's Island a
cords of public transactions in the hands of a chief.
Dentalium entalis, L., but described by Nuttall as
belt composed of dentalium shells much resembling
Dentalium pretiosum; Dentalium is
a white cylindrical shell, resem-
bling the shank of a common clay
pipe. What is more curious, the
remains of a Celtic warrior were
found near Salisbury, and among
the ornaments was a necklace of
dentalium shells. Two skeletons
found in Dublin, 1838, had neck-
laces of Nerita littoralis. The
ancient Egyptians had also neck-
laces of enamel beads alternately
blue and white. The Gauls had
beads and pierced discs. Might
not this bead money have been the
origin of the Chinese pierced
coins? Much more could be said
about the different objects used in-
stead of money. I annex a sketch
of a wampum string and belt.—
BERNARDIN.

shortsighted, and can always see better through a
[2221]-SHORT SIGHT.-TO ETHARDO-I am
telescope by keeping my spectacles on.
telescopes specially constructed for myopy.-G. E
There are no

CRICK

[2223.]-ENGRAVING ON SLATE.-I do not know whether there are any special tools for this purpose, but if I wanted to do anything of the kind, 1 vers' tools. should get some of the larger kinds of wood engraThey are to be obtained at any of Buck's shops in London. If the figures on the dial are required of a large size, they should be cut out with a chisel.-SAUL RYMEA.

[2181.]-DERBY CEMENT is a proprietary article,
and its manufacture a secret. Ask how to make a
good cement for mending jet, china, &c., and you willUse the ordinary gravers, of a large size. The work
get lots of good answers.-LUKE THE LABOURER.

[2223.]-ENGRAVING ON SLATE.-To F.R.A.S.
is very pleasant. Sold at Buck's.-G. E. CRICK.
[2225.]-VACUUM IN CYLINDER.-In a high pres
sure non-condensing engine the piston has frequently
to be forced back at a pressure of three or four pounds
above the atmosphere. This is partly owing to friction
in the steam ports, pipes, &c. If the exhaust pipe is
too small, there will of course be a great amount of
back pressure. I once heard of a partial vacuum being
obtained by leading the mouth of the exhaust down
to the surface of a stream, but I cannot say if this was
actually the case.-MACHINATOR.
To "Vacant

Head." You had better buy what you want, at 6d. per
[2226.] - TINCTURE OF IRON.
oz. It will never pay a man to make his own medi-
the stomach has to be acted upon.-G. E. CRICK.
cines. A little knowledge is a dangerous thing where

[2226.] TINCTURE OF IRON is made from the
spirit. No one can make it as cheaply as he may buy
sesquioxide of iron, hydrochloric acid, and rectified
6d, and will make 30 or 40 doses.
it in small quantities. An ounce may be procured for
As to its medical
properties, no human being can condense an account
of them into three or four lines. It is a tonic, and is
used in 20 different diseases at least.-LUKE THE
LABOURER.

[2182]-CONSTRUCTING COIL-If "Nemo" has not already got his wire for the primary coil I would recommend the following dimensions:-Diameter of soft iron core, 1 in.; length, 16 in.; diameter of primary wire, about No. 12; quantity required about 6lbs., cotton covered. There may be a little left, but that can easily be cut off, whereas it would not be so well to join a piece on. This should be laid on in three layers and well coated with shellac varnish and dried before putting on the wire for secondary coil. If he uses No. 16 he will require about 4 or 5 pounds, say 4 lbs. to be safe, laid on and coated as above. With regard to the tinfoil for the condenser, he will lb. to 21b.; let him be very careful to insulate each require about 60 square feet, which will weigh from 14 sheet well. With a proper battery, equal to 6 cells of Grove's with platinums 6" x 3", he ought to get from difference, he might depend on about 4in, with ordi4in. to 5in. spark, but as a trifling error causes a great nary care. batteries, as he would require a larger number, but if I should not advise him to use the bottle rather larger size than that given for Grove's first cost be a drawback would prefer Bunsen's of a to compensate for the slight difference power, Grove's being the best. It has generally been found that there is nothing better than the best white silk and cotton for insulating the wire; the dye gives a [2227.]-LIFE BELT.-The most reliable life-belts little loss but not much; there is are those which are sold by the Royal Humane Society. no special-G. E. CRICK. peculiarity about either the cotton or the silk used except that the quality be good. With 8 coil of the size that "Nemo" mentions, he had tissue with paper soaked in a mixture of guttapercha, better keep to the old method and use guttapercha pure benzole, and solid paraffin, which must be made with careful heat so as not to ignite the benzole. By giving four coats of shellac varnish to each layer of CB: CA. Show that tan. A C D = and CD= wire, using about three thicknesses of tissue, and saya+b (for safety) two thicknesses of the prepared paper, he ought to have a coil which it will be almost impossible to break down. Should there be any other little point which "Nemo " pleased to explain it as far as lies in my power.does not understand, I shall be T. S. C.

in

[2188.].-BICYCLE WHEELS.-As I make bicycles
which drive by the back wheel (see page 506, Vol.
X, I think I can give "Gimcrack" advice as to
sizes of his wheels. If he has the small wheel in front

he can have the seat as low as he likes, and he can
also use with advantage a larger driving wheel than if
it were driven direct on the cranks and placed in front.
Still from what I can tell it is never an advantage to
have higher than 48" (beyond which, also, the machine
would look a monster.) I cannot see how he can make
the back and 30 to 33in. in front. Allow me to men-
the same ironwork do. I should get a 40in. wheel for
tion here that the roller referred to in the description
of my back wheel bicycle is not needed in turning.-

[2231.] ENCKE'S COMET. For an elaborate another page.-ED. E. M. answer to this query see "Omicron's" letter on

right-angled triangle is divided at 8, so that AD: BD [2232.]-PROBLEM.-The hypothenuse A B of a

a+b

a2

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Solution: Let A C=b, CB = a, const. parallel E D.
We have:

ED: a: AD:AB::a: a + b, hence ED=

[2140]-POOR LAD'S QUERY-If he will write to me, I will give him the best advice 1 can.-T. W. WEBB, Hardwick Vicarage, Hay, S. Wales. [It is very kind of the rev. gentleman to answer "A Poor Lad's" query by post. But would not the same or similar information be useful to other inquirers if sent to our columns? We are sure that Mr. Webb would so word his reply as to be interesting to all.-ED. E. M.] [2147.] DIVIDING PLATE.-As to holding the pulley still with a division peg, as usually made, that amounts to an impossibility. You have a long, thin spring, with a peg sticking out some in. at the top, instead of the peg being as short as possible, say in., with a knob that you can lay hold of without impeding your sight, as well as saving your finger nails, and avoiding hurting the fingers in pulling back the strong springs that are sometimes put to make up for the abominable length of the peg. The peg ought to be fixed to a bar that will not bend at all, working on a joint at the lower end, and forced up to its work by a spring of some sort, or a wedge jammed in behind it, against something solid; and this plan would help to preserve the holes. I think a good plan of holding a pulley steady would be to let the edge run close against a firm block of wood, and set it fast after every time of shifting by a loose clip like a car-ing, "Clavis Campanalaria" I am unable to give the penter's bench vice on a small scale.-J. K. P. price or date of; "Campanologia Improved; or, the Art [2165]-THE WORKMAN'S INTERNATIONAL of Ringing Made Easy," 3rd edit., London, 1733, is a EXHIBITION will open at the Agricultural Hall on little book that contains all the terms made use of, July 5th. The last day on which applications for space and may be met with occasionally on a book stall. It will be received is April 25th. I shall be happy to forward every information, and space papers, &c., to anyis now many years since I ceased to be-A COLLEGE YOUTH. one sending a stamped directed envelope, or they can be had on personal application at 150, Strand, or be--was the money of the Indians of N. America (wam[2217.]-THE WAMPOOM-or better, the Wampum tween 7 and 10 p.m. at the St. Mark's Club, 11, Brown- pum is an Iroquois word meaning mussel). It con--TAUTAU. street, Duke-street, Oxford-street, W.-ROBERT BUR- sisted in little tubes made of shells, fastened upon GESS, Local Secretary, 22, George-street, Oxford- belts or strung on deer sinews and worn as necklaces. street, W. The purple beads were made of the clean parts of the

SAML. JAMES.

a2

a+b

EC:b::DB:AB::b: a + b,

EC =

a+b ED

EC 67

England," 3 vols, 8vo, 158., Parker, 1853.
[2196.]-NAMES OF PUBLISHERS." Annals of in the triangle E CD we have tan. A C D = ---
On Bell Ring-

and C D = √ E D2 + C D2 = √ a1a + ba
-BERNARDIN.
a + b
[2237.]-SALERATUS.-This is much used in the
United States for making cakes. It is a carbonate of
potass, and contains a trifle more carbonic acid than
pearlash may be considered as one and the same thing.
pearlash; but, for domestic purposes, saleratus and

which contains a greater quantity of carbonic acid [2237.)-SALERATUS-Is a carbonate of potash than pearlash, and is used in cookery.-MINNEHAHA

"Pharmaceutical Stu242 –DIGITALIN.– Let dent" take this advice: In all his proceedings in acquiring a thorough knowledge of pharmacy seek for a definition of the articles he uses, and he will scarcely ever fail. Had he turned up the P. B. for acetic acid he would have found the acid ordered in the formula for digitalin clearly defined.-H. E. GODFREY. [2242]-DIGITALIN-From "Pharmaceutical Student's letter (1945) it seems that he not only distilled off the alcohol from bis extract of digitalis, but carried the evaporation to perfect dryness, perhaps even plying the heat afterwards, as he seems to have made the extract so dry that he could powder it. I should suggest this as the probable cause of his failure.-E. K. 2249-NUT SHAPING IN THE LATHE. The nosepieces carrying the nuts are held in place by a small taper steel pin, which, going through the two sides of the hole and the nosepiece, holds the latter firmly in place.-W. H. N.

NOTES AND QUERIES.

[2259.]-TO "FEU FOLLET."-Will "Feu Follet" be pleased to give his process for bleaching wax by chlorine without destroying its burning qualities? -A YOUNG MECHANIC.

ALPHA.

[2260]-PORTABLE CARPENTER'S BENCHWill any reader furnish me with a plan or a few sugap-gestions for making a portable carpenter's bench? [2261.]-PITCH OF PROPELLER. brother reader give me the most correct method for calculating the pitch of a screw propeller? A diagram, showing how the blade should be divided, will greatly oblige.-THOMAS J. O'CONNOR.

(2253]-YACHT BUILDING.-1 think "Notes on Yachts by Edwin Brett, Low and Co., may suit

"Steersman."-G. E. CRICK.

[2254]-DOORS.-Walnut timber requires quite as much seasoning as any other wood, and is not at all adapted for making doors, being now used principally The labour of working it will more than for veneers. amount to the price of oak.-MINNEHAHA.

[256]-CLEANSING CASKS.-First wash the inside of the cask with cold water till it is perfectly clean, then, for an 18-gallon cask, mix two gallons of cold water with half a pint of chloride of lime, which pour into the cask and shake it for about a quarter of an hour. Then turn it out, and again wash the cask A strong smell of lime will with pure cold water. arise for some time, but in two or three hours it will be entirely gone. No fear need be entertained that any taste or smell of lime will be given to the ale.

TAUTAL.

-Will some

"

[2262] RHUMKORF'S COIL.-Will "Sigma have the kindness to explain the manner in which the primary and secondary wires are wound on the bobbin I believe this is the most of the Rhumkorf coil? powerful machine at present known.-THOMAS J.

O'CONNOR.

[2263.]-DISSOLVING AMBER.-Will any brother reader tell me how to dissolve amber?-CATSEYE DIAMOND. [2264.)-PENDULUM.-Having bung two pendulums on a rod and setting one in motion towards the other, the one that was remaining perfectly still, after a few moments, began to move with the other. Will someone describe what caused the other to move?-CATSEYE DIAMOND.

[2265]-SCREW CUTTING.-I want to form a screw 4in. pitch, 4in. diameter, and 12in. long, on a piece of in. wrought tubing, with sheet zinc. What shape will it require to be cut in the sheet, so as to form the screw round the tube? A rule for doing this from some of our correspondents will much oblige.

J. G. W.

[2266.]-WASHING MACHINE.-Will some reader kindly inform me how to make a washing machine for domestic use? Being only an artisan I cannot afford to purchase one of those expensive machines (1) advertised — ARTISAN.

[2258]-EQUATIONS.-I beg to send a solution to the equations in the first number of the present volume. In the 1st equation we have given z-α #-。

+

=0

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44

[2267-WORK ON ELECTRICITY.-Will some reader (perhaps Sigma") kindly recommend me a (2) good moderu work (stating price) on electric science, describing in detail the theory of the induction coil? A work whether in English, French, or German, would suit.-S. T. P.

(3)

(5)

b;

[2268]-POLES OF MAGNETS.-If my question (4) will not be anticipating "Sigma's "intention, I should like to have explained to me why the magnetic poles or points of maximum attraction lie, not at the actual extremities of the magnet, but a distance within, &c. ? The reason of this fact in magnetism has always puzzled me, especially as I find the same fact mentioned, but not explained, by several other emiElectro-magnets, I understaud, Bent electricians. have their poles much nearer their extremities than permanent magnets, thus explaining, according to the law of inverse squares, why the magnetic field in one (1) case is so much greater than in the other; but what I (2) want chiefly to know is, whether there is any theory explaining the point in question.-H.

... by subtracting (2) from (1) (b + k) x − (α — k) y + (a + h) x + (b − h) y = 0; or (a + h) x + (b − h) y = (b + k) x + (α - k) y;

I

a x + h x + by hy = b x + ka + ay

≈ (a + k − b − k) = y (a + k − ・・・ x = y

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k)

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CANDLE-BEARING TREE.-This curious tree is only met with near the river Chagres, in the Isthmus of Panama, and was discovered there by Dr. Siemann. It is the fruit of this tree which so perfectly resembles, in shape and colour, that of unbleached wax candles, which has given rise to its popular name, palo de velas (candle tree); the botanical name is Parmentiera cerifera, and its fruit is eaten by sheep. The fruit known as quamxilotte and eaten by the Mexicans as a delicacy, is produced by the Parmentiera pendulus.

[2269]-FOSSILS.-Will any correspondent inform me in what way slabs of stone containing small fossils are prepared? It appears that acid of some kind is used, which eats away the stone around the fossils, leaving them standing out like basso-relievos from the surface of the stone. If washing with acid be the only preparation, I cannot understand why the fossils, as well as the stone between them, should not be destroyed.-H..

[2270.]-MOTION OF WATER.-What quantity of water will pass through a lin. hole (round) at 381b. per square inch ?-J. CROMPTON.

[2271.]-PURIFYING NITRIC ACID-Will anyone give a method for purifying nitric acid after having used it for dipping brass castings?-J. CROMPTON. [2272.]-GALVANOMETER.-Will "Sigma " or any other electrician kindly give me a description of an indicator or galvanometer for indicating the strength or the induced current from an induction coil?—A. J. HAYWARD.

[2273.]-DR. KITCHENER'S TELESCOPES.-Is it known to any of your readers taking an interest in the telescope what became of Dr. Kitchener's instruments (about 50 in number, I believe) upon his death? Were they sold by auction, and is it known who possesses the Beauclerc object glass?-G.

[2274.]-VARNISH.-Many thanks to "Worcesterfor their prompt replies shire Sauce" and "Gilder In regard to woodcuts and prints, I to my query. suppose the same process will apply to thein as to maps, but will it answer with pencil drawings ?-IN

QUIRER.

-Will [2275.]-SUN GLASS FOR TELESCOPE. any of my brother readers kindly inform me what kind of glass is placed before the eye-piece of telescopes for viewing the sun ?-J. H. WARD.

[2276.]-GRANITE POLISHING.-Will any brother mason kindly inform me the process adopted in polishing granite?-whether putty powder or emery is employed, and how to apply it? Full particulars will greatly oblige.-MARBLE MASON.

[2277.]-GRINDING. How much wheat should millstones 3ft. 4in. and 4ft. respectively, grind în 12 hours on an average, with power in plenty? Would any practical brother reader kindly give the result of his experience ?-SERGIUS.

dents inform me the names of books or pamphlets, [2278.] DRAINAGE.-Can any of your corresponalso prices and the names of publishers, treating on drainage and sewage irrigation ?—IZGITZAR.

[2279.]-WATER.-Can you inform me how to test and analyse water, and how the standard solution of permanganate of potash is made for detecting the presence of organic matter in water ?-IZGITZAR.

[2280.]-CHINA GRASS.I should feel obliged if "Ernest" (query 1894) would inform me where to procure seed of the China grass plant or Urtica Nivea, and also the best means of separating the fibre from

the stalk, with the various processes it goes through until fit for the market?-Ross.

[2281.]-AURIFEROUS ORES.-Can any of your numerous readers give me information as to the treatment of auriferous ores, and of ores containing sulphur, arsenic, and other base metals, with the view of utilising each, together with drawings of furnaces, flues, condensing chambers, &c. used to carry out the work, also the best way to separate the gold from the pyrites-commonly called black sand-that is sent from Australia, and whether the sulphur and arsenic is saved; if so, by what process? Would the introduc tion of electricity into the mass while under treatmer t of chlorine be of any advantage, or whether it wid prove dangerous? Would a hot or cold blast be of any service?-Ross.

[2282.]-POWER OF STEAM.-Will any reader inform the writer if steam passing through a tube 32ft. long to a small high-pressure engine would act with Of course as much power as if nearer to the boiler? he is aware of the greater loss by condensation; but, apart from this, will steam act with as much force after passing through 32ft of a tube as if it only passed through five or six feet ?-B.

[2283.)-PAINTING THEATRICAL SCENES.Can any of your readers give me information on the following points:-1. How to paint theatrical scenes on coarse calico with (if possible) water colours? in order to prevent the smell of oil. A full description, including how to prepare the calico for the colour, and obtain the necessary colours? 3. Could any varnish how to mix the colour, is requested. 2. Where to be applied that would not crack on being rolled up, to [2284.]-MEDICAL COIL-TO "SIGMA."-Will protect the colour?-H. N. H. Sigma" oblige by telling me how I am to know the primary or secondary handle of his medical coil as [2285.]-MIXING BRASS.-Will some reader tell me described in Vol. X., p. 5137-J. S. the way to mix common soft brass?-CASTER.

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[2286.]-GENEVA CYLINDER.-Will some horological reader kindly give directions for selecting and turning in a Geneva cylinder, describing how to arrive at the different heights, and stating whether the cylinders when bought from the shops are with or without plugs, or are the plugs to be bought separately? also if the cylinders are ready escaped, or is that left for the workman?-CYLINDER.

[2287.)-DAMAGED LENSES.-Is there any means of making a telescope of service again, the glasses of which have become opaque-having been in a fire? If so, how can I do it?-W. H. P.

[2288.] -CHARCOAL FOR RUBBING DOWN SILVERED CIRCLES.-Can any of your many wellinformed correspondents give me a few hints for making the above? What kind of wood to use? what heat to apply? whether to be burnt alone or mixed with any other substance? Any information would be welcomed.-IOTA.

[2289.]-GLYCERINE.-I find that it does not pay to distil my glycerine. Will any scientific friend inform me how I can make glycerine of a brownish tint perfectly clear, with a small outlay of money, and little loss of material ?-GLYCERINE.

[2290.]-BROAD LEAD PENCILS.-A very useful pencil for drawing foliage, &c. was in use some time ago, invented by an artist, Mr. Galpin. Can anyone tell me where they are to be purchased now?-INQUIRER,

[2291.]-ENGRAVING ON METAL.-Will "Engraver" kindly tell me the use of the scrapers and points which he mentions in his query 2010, and to what temperature the gravers are lowered?-YOUNG

COUNTRY WATCHMAKER.

[2292.]-GEOMETRICAL METAPHYSICS.-What could be the origin of the notions geometers get of regular figures-such as point, line, surface, circle, sphere, cube, &c. ?-F. BOSMANS, Louvain.

[2293.].-STRANGE MECHANICAL MOVEMENT. -Let a top-such as is used for astronomical demonstrations-be put into motion, present to the upper part of its axis the edge of a metallic spiral, the axis of the top will adhere to the metal as if it were a loadstone, enter the spiral and follow its curvation; at the end of the spiral it returns backwards, and repeats again the same motion. The sight of this struck me because it appears against the rules of common mechanics. Could any of your readers favour me with a satisfactory explanation of that curious phenomenon? E. V. V., Louvain.

[2204.]-THEOREM.-Would some of your mechanical correspondents favour me with a demonstration of the following ?-With the same perimeter the area of the circle is greater than the area of an ellipsis.-E. V. V., Louvain.

[2295.]-PROBLEM.-Where ought to be the centre of a circle C for bisecting another C1 in two equivalent parts ?-E. V. V., Louvain.

[2296.]-MONOGRAM DIE.-Can anyone tell me how to set to work to cut a copper counterpart to a steel monogram die? What tools are required ?CANTAB.

[2297.]-VIOLET INK.-Will anyone give me a recipe to make good dark violet ink?-CANTAB.

[2298.1-REMOVING OIL PAINT FROM SILK. -I have a large bit of white silk which has been sized and painted on with ordinary oil colours. Can I get the paint off without injuring the silk ?-CANTAB.

[2299.]-GENERATION OF ELECTRICITY.-TO SIGMA."-I venture to ask "Sigma" to tell me what is the cause of the spindles in our spinning mules that if I touch one with my finger it will make sparks generating electricity when running to such a degree fly off and electrifies the piecers every time they piece a thread. If he could give me any advice how to cure a great favour.this he would be conferring [2300.]-MOULDS.-What material is best for moulds LANCASHIRE LAD. for fancy ornaments? Would gutta percha answer as well as beeswax ?-B. C.

[2301.]-WEIGHT OF WROUGHT IRON GATES. Will some reader inform me of the best method to obtain the weight of wrought iron gates and fencing

y measurement, or where I can get good books on the subject?-W R. SOUTHWELL.

[2302]-POLISHING SCOTCH PEBBLES.-Would some one inform me how to bring the surface of a pebble to an even face, and afterwards how to polish? AMATEUR LAPIDARY,

[2303.]-TEA URN.-I have a tin tea urn which makes the tea a very dark colour, and quite tasteless. Some time ago the tap came out, I had it put in by a common tinman, and since then it has never been right, although before it was an exceedingly good. What is the cause ?-CAUTION.

one.

[2304.]-PALO DE VELAS.-What is it ?-ROBT. J. JOHNSON.

[2305.]-FORMANISING.-This is a process of preserving wood. I wish a few particulars about it from some of our kind brother readers.-CONTRACTOR. [2806]-MORE STEAM WANTED.-The enclosed is a section of a small boiler I have 3ft. 6in. high and 1ft. 8in. diameter, and which I wish to make drive an engine with a 3 in. cylinder at a about 60lb. or 70lb. pressure, but I find I cannot make steam fast enough. I therefore wish to ask some of my fellow readers to kindly inform me if putting in-say, four or five lin. tubes round the smoke flue (which is only 3in. diameter) would make it answer my purpose, or is the only remedy a larger boiler, and if the latter, what sized boiler should I require ?-D. C. W.

[2307.-RIVET MAKING.-How and in what way are rivets made by machines-about fin. diameter ?

RIVET.

I

[2308.]-MELTING CAST STEEL.-I have been trying to melt some old scrap steel in a crucible, and have succeeded, but I find it too hard to work. should feel obliged if "Practical Moulder" would give any information regarding flux.-SCRAP STEEL. [2309.]-ETCHING ON GLASS.-Would any brother reader kindly give me a few hints on etching on glass with fluor spar?-BELLE ISLE.

[2310.]-SPIRIT TAPS.-Wanted a good method of grinding spirit taps.-BELLE ISLE.

[2311.]-NEW WORM FOR VICE BOX.-How can I put new worm to a vice box that has slipped thread? I have seen one or two that have been done, and which are as good as new.-A. E. B.

[2312.]-HISTORY OF IRELAND.-Will any of your numerous Irish readers kindly inform me of a complete, reliable, and moderately-priced history of Ireland?-A YOUNG IRISMMAN.

[2313]-ENAMELLING CAST IRON.-How can I procure a white enamel on cast iron, with full parliculars ?-ARTHUR JONES.

[2814.]-POLISHING FRETWORK.-I should be glad if "Guillaume" or some other correspondent would inform me of the whole modus operandi of polishing whether he uses any size to stop up the little holes and crevices in woods like oak preparatory to applying the polish. The objects I wish to polish are fretwork; also where to buy the proper polish? The stuff I have by me is very thin.-C.

[2315.] TELESCOPE CONSTRUCTION.-Why are astronomical telescopes constructed so long, as I have two of 2ft. and 4ft. focus respectively, and I find that by using an eye-piece (with the small telescope) half the focus of that I use with the large telescope, it equals the large one in every respect, and I cannot see what advantage the large one has over the small one?—

ASTRONOMER.

[2316.]-THE SLIDE VALVE.-Can any of your correspondents recommend a good book on the slide valve and the valve motion, and the name of the publisher, and the price?—A Constant READER.

[2317.]-CURVATURE OF THE EARTH.-Perhaps some professional correspondent will give his "field notes" of practical curvature allowance, so that others may plot and test it. Along a still water line preferred.-THEOdolite.

[2318.]-ETHEREAL SOLUTION.-Will "Sigma' kindly inform me where to procure the ethereal solution of gold spoken of in reply to Mr. Sharp (2040), also the means of applying it, and whether the steel requires any preparation? If he will he will greatly oblige.-B. S. BURDEN.

[2319.]-BOILER.-I am about putting down a small steam boiler-the steam to be used for boiling two troughs for bone button making, &c. I should be glad if some of your readers could inform me the best way, and if I can put water in the boiler when steam is up without a pump? steam will not be required very high-JOHN JONES.

[2320.]-CHIMING.-I want to make or alter a clock so as to make it chime the half hours as a ship's bell is struck-thus, at half-past 12 to strike 1, at 1 to strike 2, at half-past 1 to strike 3, with the same pause between the second and third strokes as in an ordinary clock exists between the strokes for the quarter and half hour; this would go on till 4 o'clock, when it should chime 8 in four pairs of beats, and then commence again at half-past 4. The pauses to be between the second and third, the fourth and fifth, and the sixth and seventh beats. Can any brother reader say how this can be done?-AN OLD SALT.

[2321.]-SWAN'S PROCESS.-What is the modus operandi of the autotype or carbon photographic process invented by Mr. Swan? and is it successful upon parchment?-SCRIBO.

[2322]-PRIE DIEU.-Can any reader tell me where I could obtain designs for a prie dieu to be executed in oak wood-not too elaborate-but that necessitates a little carving in the panels, &c.?-GOOD CATHOLIC.

[2323-WATER POWER.-Can a brother reader inform me what power may be obtained to work machinery from a runner of water I have-about 200

WATER LINE

cubic feet per minute (often more) by causing a dam
to be put across the brook, and giving a pressure as
shown on sketch to turbine or other form of wheel?
Will the accumulated water in brook be an aid as force
to the quantity regularly running as named above, a
length, say, of 80 yards, being back water to dam?-
G. P.

[2324.]-GYMNASTICS.-As I am going to construct
a pair of parallel bars, I wish to know the best plan
of having them fixed up. What I have seen were
fixed in the ground, but I fear they would soon get
rotten, being exposed to the weather. In "Modern
Gymnast" a sketch is given of a portable pair fixed to
a frame. Would "Bierlala" or any of your gymnast
correspondents who have had experience in the matter
be so kind as to advise me which is the best plan?
Is there not a process which would render the wood
not so liable to decay?-GYMNASTIKOS.
[2325.]-IRON ORES.-Will G. E. Davis inform me
how to estimate the quantity of protoxide and peroxide
in iron ores ?-J. N., North Country.

[2326.]-VIOLIN.-Can any of your readers tell me
the exact pressure on the belly of a violin strung to
concert pitch ?-CREMONA.

[2827]- READY RECKONER-Can any brother
reader inform me where I could procure a ready
reckoner for calculating tons and cwts., giving the
fractions from 1d. to 58. per ton ?-J. W. M.

[2328.]-DEFECTIVE GUTTER.-I have a double-
roofed building; the gutter is of Glasgow cast iron,
and in wet weather the water oozes through the pores
in small drops and makes the building very wet. Can
any of your readers inform me what is the best thing
to do to make it perfectly waterproof?-SALOP,
[2329.]-MATTING.-Can any reader tell me how
to clean matting ?-MINNEHAHA.
[2330.]-THE BOOMERANG-I possess three speci-
mens of the boomerang, but they totally fail to
achieve what I have read of them. Will someone
suggest the true method of using them?-SALMO

SALAR.

[2331]-PATENT DRYERS. Can any of our readers inform me of what patent dryers (for paint) is composed?-H. BEECH.

[2332.] -- UNNOTICED QUERY.- How are the perforated and traced patterns for embroidery and braiding effected on paper, and on the materials, directly?-STITCH.

[2333]-BRILLANTINE.-Will some kind reader of the ENGLISH MECHANIC inform me how brillantine is made?-PERFUME,

When tallow

tions from the mechanic how to work it
is put in (when there is steam) it is all blown out over
the top of the engine. The fire is kept on in the
engine all night, so that we cannot get any tallow on
the lower end of the lubricator before the end of the
week; also, will you inform me the best way to apply
the needle lubricator to the motion bars-the present
oil-cup is fixed in the centre of the bars? I find the
needle lubricators act first-class on all the bearings of
the engine, and are most invaluable. I would advise
all owners of engines to have them applied, as they
are moderate in price and most simple to fix, and
when filled a quarter of a pint will last a week.-PRO-
GRESSIVE AGE.

[2344.]-CYLINDER.-Perhaps some of my fellow randers will give their opinion upon the following form of cylinder-it occurred to me a day or two back. Possibly it may be useful to some who cannot bore a

A

true cylinder :-A A is a long cylinder sliding steamtight in the outer cylinder-it is made steam-tight by glands, the same as in the piston-rod. Steam being admitted at one end of the outer cylinder, it naturally acts upon the inner one as on the piston of other engines.-W. H. THORPE.

diagram, &c., showing the geological distribution of [2345.)-REPTILES.-Will some reader give me a reptiles throughout the globe? -LYNX.

[2346.]-GEOLOGY. Can some one mention the name of a good manual on geology-price about 108, ?

-PERMIAN.

[2347.]-THE TELESCOPE.-1st. How can I get my telescope set exactly north and south, also east and west? It is fixed with cement into the top of a large drainpipe filled up solid, to which is attached a triangle of iron with legs-one at each angle, one of which, much longer than the other two, is let into a large square of freestone, and fixed with lead. The whole telescope, stand and all, can move round this leg to any distance, and can be raised or lowered by, means of two nuts as much as needful. The two other legs rest on pieces of tin, and can be shifted east or west, as required. 2nd. wishing to look at the sun, I took out my "flat" and removed all the silver and then replaced it, and then found that by using a piece of coloured glass between my eye and the power, I could do so with little or no danger to my eyesight-at least, so I think-am I right or not? 3rd. How can I convert north polar distance into north or south declination ?-H. A. C.

[2348.]-ELECTROTYPES.-I thank "Sigma" for the ready way in which he answered my question. It

is the outer surface that I meant, and not the one in contact with the mould, so I shall have to make my meulds on a different principle, as he says the outer surface is generally rough, and the articles I am coat

that the inner or smooth surface is inside, and is not seen, while that part that is visible is the outer and rough surface. Will he kindly tell me how I should make moulds for this purpose, as it seems to me to be different to making medallions, which I can manage very well?-E. R. H.

[2334.]-POLISHING HORN AND SHELLS.-Willing are small wax figures in the shape of a man, so
some brother reader kind'y tell me the way to polish
buffallo horns and tortoise shells?-W. CROCKER.
[2335.]-CONTACT BREAKER.-Can any of your
readers advise me the best form of contact breaker for
an induction coil to give a 7in. spark? The ordinary
forms are a source of continued expense by the platí-
num points melting away.-A. E. TUCKER.
[2336.-BRONCHITIS.-Can any brother reader in-
form me of a cure for the above complaint, or rather
what it has left behind it? About three years ago I
had a very severe attack of it, and ever since I have
been more or less affected in the chest and windpipe,
with a husky voice; very apt to take cold, with a
cough not very violent, but very distressing. All that
I have taken seems to have no effect on my voice. I
sometimes fear it will end in consumption if no remedy
can be had. My age is 28. Any information will be
a great favour.-A THREE YEARS' SUFFERER.
[2337.)-STEAM INDICATOR.-Will some reader
kindly tell me of any work on the steam indicator?-
MARINE.

[2338.]-SAW TEETH.-Would "Mill Sawyer" be so good as to give a sketch of what he considers to be the best form of circular and deal frame saw teeth? R. T. S.

[2339.]-SIZE OF PULLEY.-I have an Sin. centre screw cutting lathe with overhead motion, and I want to drive it from a shaft that is running at 24 revolutions per minute. Will any brother reader kindly tell me the diameter of pulley I require on this shaft to drive the lathe to speed?-MARINE.

[2340.-WIRE COVERING.-No one seems to have
noticed my query asking what sort of cotton is raost
suitable for covering wire. I have a covering machine,
but cannot get a suitable cotton for my purpose.
Perhaps some one will give me the requisite informa-
tion?-OVER SANDS.

[2341.]-CANOE.-I thank "Maty" for his notice of
my question respecting a canoe, and beg to inform
him I want it of suitable size to carry one person, and
to be similar in shape of those used by the canoe clubs.
Would be glad of any instructions he could give me as
to best material, or anything else.-OVER SANDS.
[2342.]-FACINGS FOR HARMONIUM KEYS.-
My harmonium keys are of worn-out ivory. Can any-
one suggest a method of facing them either by enamel
or otherwise?— PROGRESS.

[2349.]-BILLIARD BOARD-Can any of your readers give me some practical advice on this matter? How to set about making one, and the modus operandi? Where to obrain a slate bed of 8ft. by 4ft., and probable price? Is not also the cloth very expensive if wanted for a larger-sized table? Can you buy the cushions ready made? Guess (excuse the Yankeeism) there be a proper place for each of these things, but where is it, and how do you work the oracle? Any information will be very acceptable. If a billiard table of an average character could be economically made by an amateur, doubtless many of your readers will feel inclined to try it.-CANTAB, London.

[2350] RAISING WATER.-What is the best and cheapest way of raising water from a well 30 yards deep?-W. S. O.

[2351.1-ALCOHOL.-What is the best chemical test to find the presence of alcohol in any kind of liquid? -ALCOHOL.

[2352.]-OVAL-How can I get a correct oval, and whether the width is governed by the length? I can strike them several ways, but they are not correct, as I think an oval should not contain any part of a circle. G. HUNT.

[2353.]-WORK ON THE VALVE.-Does any reader know of a work in which I could find a calculation on the dead weight valve. Sav, suppose I have a 2in. dead weight valve to fix on a boiler, and to be weighted to 80lb. By what rule am I to make my calculation ?-JOHN KERSHAW.

[2354.]-SPRING STEEL.-I wish to temper a large quantity of springs, similar to the bicycle spring upon which the saddle is fixed. As I cannot make these sufficiently elastic by tempering in the smithy fire, I should be very much obliged if some experienced hand will give me the best shape of oven, &c., for this purpose, with description how to go about my work to accomplish this object.-BRITTLE.

[2355.]-CANOE BUILDING.-Will "Steersman " or one of my fellow readers be kind enough to inform me what wood is best for the keel and ribs, also the dimensions for the same for a wooden canoe about.

20ft. in length? I have examined several, and find the keel is curved at the ends to form the bow and sternpost. How is this managed, and how are the ribs bent. to their proper size? A section would assist me very much.-C. D. R.

[2343.)-LUBRICATORS.-I shall deem it a great
favour if me of your numerous correspondents who
are qualified by experience of Roscoe's self-acting
lubricators will advise as to the following:-I am the
owner of a 10-horse traction engine, and have had one
of Roscoe's No. 2 lubricators fixed by a practical [2356.]-GOLD.-I have some gold in a finely-divided
mechanic on the top of the dome-the engine was built state mixed with sand. Will some chemical contribu
by Fowler, of Leeds; my driver received the instructor inform me the easiest way of separating the same-

APRIL 1, 1870.]

quantity of gold is about 10 grains, and of sand abet 200 grains"-RUDIS.

-IRON SECONDARY.-Has any brother wder made an intensity coil, using fine fronwire for the Bondary, if so, will he please state the quantity and reale?-GT. BOURTON.

[2358.-WINTER'S ELECTRICAL MACHINE.— I am about to construct an electrical machine on this principle, but do not exactly understand how the cushions are made and fixed. Will some brother reader who has one be kind enough to describe this part minutely, with drawings?-SAPIENT.

[2359. GALVANIC BANDS.-Will "A Suffolk Amateur" be so good as to give us a drawing of his galvanic band? I do not quite understand the joining of the metals. Why must they be whipped together with thread and varnished?-MINNEHAHA.

USEFUL AND SCIENTIFIC NOTES.

METHOD OF COPYING STATUARY IN VARIED POSITIONS ON ONE PLATE-I can best explain my method by giving my first experience. I had occasion to make some card copies of a small marble stafue of the "Greek Slave," and thinking it would make a much more attractive picture if it could be eopled in a variety of positions on one card, I resolved to attempt it. I took for the background a strip of dark brown cotton velvet, arranging it so that the lower portion covered the top and hung a few inches over the edge of a small stand. Placing the image on the centre of the stand, I got the proper size and focus with the ordinary camera, and made a faint mark around the base on the velvet, then moved the image to the right and left of the first position, being careful that one position should not interfere with the other, and marking around the base each time, that I might know just where to place it in the subsequent operations. I then prepared and exposed my plate, covered the camera, moved the image to the next position, and exposed again as before. On developing my plate, I found I had a remarkably fine negative of one object in three positions. Almost any number of positions may be obtained in this way, but the time of exposure must be lessened as the number of positious Increase, and each position should receive an equal exposure. Whether the idea is now to every one I cannot say, but that it may be a useful one to many is evident. To such I give it. Those who photograph statuary for the stereoscope would do well to try it.-G. W. White, in Phil. Phot.

47

ANSWERS TO CORRESPONDENTS.

at High-street, Birmingham, but has not been there for six

DESILVERING.-In many cases it may be useful to
know a liquid which will dissolve silver without
HOWARD RYLAND, OF BIRMINGHAM.
attacking copper, brass, or German silver, so as to
remove the silver from silvered objects, plated ware,
AMR. HOWARD RYLAND offered last year, through our pages,
to supply for 13 stamps a key label, embossed with name and
with six parts sulphuric, heated in a water-bath to
etc. It is simply a mixture of one part of nitric acid
160° Fahr., at which temperature it operates best. By address of the sender. Advertising at first from Union Cham-
bers, Union Passage, Birmingham, Mr. Howard Ryland after-
this means the old silver attached to plated ware, old
daguerreotype plates, etc., may be removed and saved wards-probably for very good reasons-changed his address
without any necessity for wasting acids in dissolving to 79, High-street, Birmingham. Five correspondents have
written to us, stating that they sent stamps to Mr. Ryland,
a large amount of useless metal.
CURIOUS FACTS IN REGARD TO SOUND.-The but cannot get their labels. Two of them have addressed the
"Borough of Birmingham Police Office, 1st February, 1870.
following curious observations in regard to the trans-police authorities on the subject, and have received the fol-
"SIR,-Sergeant Jenns reports that H. Ryland has an office
mission of sound have been carefully verified by an lowing letters:-
motive is heard 3300 yards through the air; the noise
extended series of experiments: The whistle of a loco-
of a railway train, 280 yards; the report of a musket
and the bark of a dog, 1800 yards; an orchestra or the
roll of a drum, 1600 yards; the human voice reaches to
a distance of 1000 yards; the croaking of frogs, 900
yards; the chirping of crickets, 800 yards. Distinct
speaking is heard in the air from below up to a dis-
tance of 600 yards; from above, it is only understood
to a range of 100 yards downwards. It has been ascer-
tained that an echo is well reflected from the surface
of smooth water only when the voice comes from an
elevation. Other similar phenomena in connection
with the transmission of sound have been observed,
but the results disagree either from inaccuracy in the
observations, or from the varying nature of the cir-
cumstances affecting the numbers obtained.
variations occur to an extent of ten to twenty per
The weather's being cold and
cent., and even more.
dry, or warm and wet, are the chief influencing causes.
In the first case, the sound goes to a greater, and, in
the second, to a lesser distance.

Such

DR. USSHER'S ADVICE.-To be pasted on the fly-
leaf of the ENGLISH MECHANIC and all other books-
"If thou art borrowed by a friend,
Right welcome shall he be
To read, to study, not to lend,
But to return to me.

For oft imparted knowledge doth
Diminish learning's store,

But books, I find, I often lent
Return to me no more.'

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Read slowly, pause frequently, think seriously, keep
cleanly, return duly, with the corners of the leaves
not turned down.

THE MANCHESTER STEAM USERS' ASSOCIATION. We have just received the annual report of this useful association. The report says that during the past year 58 boiler explosions came to the knowledge of the officers of the association, which boilers were By these explosions 86 not under their inspection. INFLUENCE OF SEWING MACHINES ON lives were lost, and 126 persons were injured. There HEALTH-Some prejudice has been excited against can be no doubt that the association does good work, the use of sewing machines on the score of their alleged and not only the steam users, but the country is inAs the result of some debted to It-in the first place, on account of the acin preventing; and injurious effects on health. investigation on the subject, we (British Medical Jour-cidents it is instrumental nal) may avow our conviction that these statements secondly, for the practical information it distributes have been greatly exaggerated. They apply, we be- through the press monthly for the benefit of all. lieve, chiefly to those worked by one foot only; and we are quite unable to discover that there is any kind of objection on the score of health to those in which both feet are employed. In America, where the use of machines is yet more common than with us, the atten-" tion of medical men has been a good deal directed to the subject, and with, we believe, tolerable unanimity Against the double pedal machine in comof result. mon use in England, as far as we can learn from inquiry amongst those who have had them for many years in constant employment, there is not the slight est evidence. Of their sanitary advantages in saving time from a sedentary and very tiresome occupation, and thus favouring relaxation and exercise, it is not necessary that we should speak.

In

THE SUN.-Never, surely, says the Athenæum, has the sun been so much looked at as now! Europe and America, in India and at the Cape, in any place where there are telescopes and spectroscopes, and astronomers to use them, there the sun is closely At Kew Observatory photoheliography is watched. a part of the regular daily work of the establishment, and from time to time the results, and the conclusions they warrant, are laid before the Royal Society. Out of all this, it is thought that our knowledge of the sun's constitution must be increased. All possible advantage will be taken of the eclipse of the sun in December next; and under instruction from scientifle committees, parties will be sent to Algiers to make observations, aided by the best of modern aрTHE AMATEUR MECHANICAL SOCIETY.pliances. Meanwhile, Father Secchi, of the ObservaThe first annual dinner of this society took place on Thursday, the 17th inst., at the Freemason's Tavern, Great Queen-street. Among the members present Were Henry Perigal, Esq., F. R.A.S.; Colonel Clarke, Capt. Sandeman, and many others.

tory at Rome, is publishing every day a picture of the
sun, in which all the visible spots and all the promi-
nences, with their changes, are represented. A daily
solar bulletin, though a rough one, may perhaps be

useful.

weeks. ford.

There is no

The last time we heard from him was from HereHis letters are called for by his father. doubt but that they are swindlers.-Yours truly, "G. GLOSSOP, Chf. Supt., J.A., C.C. "Mr.

99

"Borough of Birmingham Police Office, 20th Jan., 1870. "SIR,-In answer to your letter of the 19th instant, I beg to say that our Sergeant Jenns has been to Union Chambers, and finds that a Mr. Ryland did live there about that time, Several persons have been making inquiries for him but has since removed to Hereford, but cannot ascertain since he left, upon the same subject, and no doubt he is a where, "GEO. GLOSSOP, swindler.-Yours obediently, "Per W. MANTON, Detective Inspector.

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ANOTHER TESTIMONY. VELOCIPEDE BRAKE-CHAIN. - When began to advertise, we had no idea of the farreaching power of your journal. By its use we brake-chain have received applications for our from all parts of the Three Kingdoms, and from all sorts and conditions of men; while numerous testimoWe are confident that if we had gone to work in the nials to its utility attest the favour in which it is held. slow and old-fashioned method of introducing it to have elapsed before we had done as much as we have the dealers and leaving it in their hands, years would done in the last few months. Among others, we may mention that the chain has been adopted by His Royal Highness the Prince Imperial of France, who has honoured us by expressing himself most unqualifiedly in its favour, We congratulate you on your enlargement and improved appearance.-DAVID HARCOURT and Co., Crank, Sash, and Shutter Chain Manufaeturers, The Lozells, near Birmingham. TIE following are the initials, &c., of letters to hand up to the first post, Friday, March 25:

66

RECEIVED.-C Fletcher, J. H. Morgan, "J. W. B," Novice,
H. E. Hudson, A. Slade, Trübner and Co., W. Johnson,
"E P. H.
Jun., J. Edmonson, Hobart Lang, "G. S. M.,'
V.," W. Moor, Junr, "A. G," J. Gillingham, Thos. Winter,
Wm. Pearce, "C. H. S. D.," W. Abercrombie, "Capt. D. D.
C.," W. O. Carter, J. Epps, and Co., W. A. Gibbons, Capt.
O. H. Stokes, Barry Close, F. G. J. Coggin, Robert Tongue,
Augustus." W.
'Gower and Son, "Nemo," "Joe Miller,"
R. T.," W. W." S. Taylor, E. H. Gibson, "Pro Bono Pub-
lico," J. Mills, l'. Webster, A Subscriber, J. W. T, Manes, J.
T. Bailey, Thomas J. O'Connor, R. Williams. H. W. Cott-
man, C. Johnson, W. H. I. P., T. Carpenter, D. Wall,
E. G., Capt. Noland, W. R. J., Rev. E. T., S. & M., Alfred
Jones, J. Whitwell, J. J. R., J. W. M., A Bushman, A. S. S.,
A Canadian, W. B. J., Act on the Square, R. Jabobs, J. H.,
John Bull, Amateur, J. G., J. Sargent. jun.; W. B. W.,
R. Gay and Co., Kingsbury and Co., E. D. B., Hy. Arling-
ton, A. Sufferer, J. D. M., John Kyle. Hy. Childs, A.
Spencer, C. J. S., Chuck, Jersey, Milly, W. C. R., Sigismond,
William Hewlett, Vulcanite, T. J. Evans, F. S. B., Aviary,
Wm. Moor, jun.; Look Before You Leap,.Q., A Good Boy,
F. D. C., Jno. Musgrave, Scrutator, T. A., F. E. B. Bomba,
W. J. H.. And So Forth, E. W. P., C. B. A, G. H. Williams,
Rev. R. G. B.

A

and Motion."

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HYDRAULIC PRESSES.-The hydraulic-or, as It has, some persons erroneously term it, the hydrostaticpress was patented by Bramah in 1796. therefore, been known to the world, the Engineer THE SIXPENNY SALE COLUMN is the only part of the paper in which can appear queries sent by John Steward, says, for seventy-four years, and is now applied in a Brightonian. "Claybrooke," "Scribo" (3rd and 4th multitude of operations, which absolutely could not queries), W. B. Harvey, J. Wroe, "Mosac," "Kola Nut," be performed at all without it. Presses exerting a "Fred," "A Youth," E. Williams. Albertus Magnus," If force of 500 tons, and having ranges of 10ft, 12ft., or A. R. T.-We know nothing of the savings bank you allude even 15ft., and being capable of exerting a force we to. Custom, which is sometimes more powerful than gramhave named at any part of the stroke, are by no means We do not stretch a single point when matical rules, has decided the pronunciation of the words uncommon. or levers we say that no arrangement of screws you refer to would supply us with a press of equal ange, power, and speed. It is not that an arrangement of levers could not be planned quite able to exert the strain of which we speak; but such an arrangement would hack all the characteristics which are essential to a mechanical device intended to serve the purposes of menufacturers. For example, had the work done in raising the tubes of the Britannia Bridge been performed by a simple lever, one arm must have been 448,500ft. longer than the other; and to enable a Ib to raise the load through 100ft., the lb. must have passed through In simplicity, in space for a distaner of 81,522 miles cheapness, and in efficiency, the hydraulic press stands totally without a rival. Whether assuming the form of the gigantic apparatus employed in bending armour plates, or that of a little 30 cwt. jack, it is equally compact, inexpensive, and elegant.

NEW DISINFECTING APPARATUS.-Mr. George Fraser, of the firm of John Fraser and Sons, exhibited and explained at a recent meeting of the Medical Officers of Health Association a new apparatus for The object which he has recently obtained a patent. 4s to supply a ready means of disinfecting all clothing, bedding, &c., that may have been used by persons suffering from fever or other infectious disease. such apparatus were erected in all populous districts, it is highly probable that the spread of many diseases would be considerably checked. The apparatus and its working may be thus briefly described:-A brick oven or chamber occupying a space 8ft. square, is erected, in the lower portion of which is a covered furnace and flue capable of raising the internal atmosphere to the required temperature, the front being A closed truck or carenclosed with a sliding door. risge is provided with shelves, racks, and doors, and it is intended to collect the clothing in these carriages from the infected houses, and convey it to the chamber. The front door is then opened and the truck placed inside, the fire lighted, and the process of disinfection takes place, sulphur or other fumes being used. When the process is completed, the truck is again taken to the house and the articles removed. The chief points in this patent are: 1. The whole of the vapours given off during the disinfection are, by a peculiar arrangement of flues, made to pass through the furnace, and are thus consumed. 2. The clothing is not removed from the truck until returned to the owner. 3. The carriage which conveys the clothing and returns the same to the house from which it was taken, is itself disinfected on each occasion, with the clothing, &c. 4. The apparatus is not expensive.

VERMILION -The blackening of vermilion which has given many much trouble, is caused by the decomposing action of light, being analogous to the darkening of the silver salt in photography, and it may be entirely prevented by mixing one-eiglith part of fine flowers of sulphur with the dry vermilion -before adding the oil.

CHIPS.

Herr Redtenbacher, Professor of Chemistry in the
University of Vienna, diel a few days ago, of apo
He had been connected with
plexy, at the age of 60.
the university since 1839.

Dr. Radzizewski, of Louvain, has discovered a new
This wax is
substance of a waxy nature in straw.
a;white, solid body, insoluble in water and the caustic
alkalies, but easily dissolved in alcohol and in ether

YOUNG ONE.-Read recent papers on the "Earth, its Figure SCRIBO-First query inserted, second has been replied to recently; third and fourth we cannot reply to. We do not answer by post. PRINTER.-Fairbairn and Co. (see advertisement). IGNORAMUS. See recent back numbers. CORROSION.-See "Useful Notes." AMATEUR cannot surely have read Mr. Proctor's papers on the earth, concluded in our last. SWIMMER-Sell your gold chips and buy a chain. To use your own words, "it would be cheaper."" GEO, DAVIS.-You are to be applauded for your fidelity to Dr. Bedford, but your letter, which contains insinuations, would lead to no good if inserted.

A FRIEND OF THE INVENTOR writes us a letter in which he says that a poor man whom he knows has invented a wonderful machine, which will save millions of money; and he wants us to give an opinion on the worth of the intion. If the machine is so valuable, it should be protected by patent, and then its value will mainly depend on the demand for it. But all that glitters is not gold, and particularly that which fascinates the imagination of in

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