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MILBURN AND CO.'S APPARATUS FOR DESICCATING GRAINS -(Described on page 4.)

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6ft. perpendicular height, with a horizontal pipe of 3in. going off near the top with a descent of 3ft. or so, to serve as a heat-trap. But this should be into a kitchen chimney finally, to ensure the continuous carrying off of all vapour, otherwise this would injure the plants. It is requisite also to have an earthenware Vessel on the top of the house, with water always in it, to ensure requisite moisture, or this heat will be found too dry for plants. Great care must also be taken of dust, or the leaves of the plants soon become covered from the cleaning out of the stove.

There is also an item of expense in repair. Though the interior of the stove, lined with fire-brick, will last for years, the sheet-iron piping, the cheapest and easiest heated, will require renewing every three years, at a cost of about 30s. to £2.

Anthracite, or malting coal, should be used, with care not to supply too much air at any one time, or overheating will be the result. This system was used for three years with No. 1708 house, as gas could not be had moderate. Should anyone be desirous personally to inspect and test these particulars of heating by gas, he has only to apply at 21, Park-street, Bath. J. B.

FIG. 3.

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TELESCOPIC.-ANSWERS TO QUERIES. SIR-In accordance with "Leo's" request (page 584), I give him my method of roughly estimating the figure of specula:-Procure an open wooden frame, similar to that of a schoolboy's slate, across which are to be stretched parallel cords of smooth whipcord, or what is better, violin strings, or catgut, in a similar manner to a harp About 6 of these strings will be enough. They should not be more than fin. apart, and must be exactly equidistant from each other. Next stand the mirror, which is to be inspected on any convenient support, with its face opposite a window, and at a distance from it rather more than its radius of curvature, or twice its focal length. Then incline the mirror slightly, until it reflects the image of the observer's head when standing close to the window. In this position then, with the face looking towards the mirror, hold up the test frame between the eye and the mirror, and parallel to it, until the inverted image of the cords is seen reflected on its sur

FIG. 1.

face. If now the mirror be spherical, the cords will appear to converge towards each other as they approach the edge of its disc; but when the mirror is truly parabolic, the cords appear as they really are, perfectly straight, and equidistant from each other. The simplicity of this test speaks for itself; and should the operator have a venetian blind to his window, that alone would be sufficient, without a test frame, to enable him to form a tolerably correct idea of the figure, providing the room is large enough to permit the mirror being placed at a sufficient distance. I should say that to give this test its best trial, the eye should be brought as near to the mirror as distinct vision will permit. Any distortion of the parallel cords will then be exaggerated just in proportion as the lines are magnified; and it preferable, the cords may be only in. apart to bear this amplification. Next in order, I must attend to my "Pupil" (page 590), or else he will think me by this time a forgetful "Pupil" seems to think "the band suspenteacher. sion the best for such as himself, with blanket to rest

on." I should think so too. He will no doubt find it very comfortable, and will do for better to rest on the blanket himself than trust his mirror there. Blankets are very nice things in their place, but I, for one, have no faith in them as supports for specula (unless, perhaps, when they are small). He should try the method explained on page 604; it will answer perfectly for a The plane for a 10in 10in. glass, or even larger. should not be less than 1in.; 2in. is still better. As to the ordinary plate, I have used a flat cut out of this material for solar observation, and it has shown the rice grain stippling very plainly; but I have not yet tried it on the stars, but believe it would work well. I may add that the cone of rays in a Newtonian, although bent or diverted to an angle of 450, suffers no other alteration beyond a slight diminution of light; the object seen is in the same position, and moves across the field in the same direction, with respect to the observer, as in a refractor.

The foregoing replies will no doubt satisfy "G. C.," on the same page. My mirrors are made of lin. glass.

I do not consider myself accomplished in the art of silvering glass, although I have produced some very decent films. No doubt scrupulous attention is required to the directions given by Browning, who, I

HORIZONTAL WINDMILL.

SIR.-In reply to "P. P." and Mr. J. Thrower, I beg to state that I should regulate the machine in the fol

[MARCH 25, 1870.

with which the predictions have been made, from an
assumed theory, so far from being the approbrium of
the" Nautical Almanac," may be its pride.
"F.R.A.S." says, that the use of Damoiseau's tables

may say, has kindly informed me that the tempera-lowing manner:-In the first place, I should weight ought long since to have been discontinued, but he ture of the room has much to do with the success of the cord A (Fig. 1), which would run over the pulley knows that there are none to replace them, and it

it. It should be not less than 70°, and great care must be taken to get the glass perfectly clean. I have found that after cleaning the glass with nitric acid, an alkaline solution is useful before the final washing with

water.

As to the question asked by "Novice," page 606, I am sorry to say I am at a loss to know what he means. I am afraid he is running his head against some imaginary post. Let him read the directions again more carefully. W. PURKISS.

ELECTRIC MACHINES.

FIG. 2

FIC.I

A

D

F

E

-B

surely cannot be an insinuation that the "Nautical Almanac" office ought to have computed others, that should better represent the observed phenomena. It is the duty of computers attached to that establishment to use, and not to form tables. W. E. P.

wheel C-with the
weight B, the lat-
ter being light
enough to allow of
the sail swinging
out in a high wind,
as in A, Fig. 2, and
thus permitting the
excess of wind force
THE RELATION OF POWER TO APERTURES
to pass by.
IN TELESCOPES.-TO "HUGO."
Secondly, I should cause the rod D F, Fig. 1, to pivot
at E, E being above the middle point of D F, and EF the explanation of "F.R.A.S." satisfactory. It is
SIR,-With reference to this subject, I do not think
consequently longer than evident, that if the magnifying power of a telescope,
D E. The effect of this cæteris paribus, be doubled, the image of the object
would be, that when the sail on the retina will then oceupy an area four times as
was at or about B (Fig. 2), E F great, and consequently the intensity of the light must
would swing back and D E be reduced to one-fourth; therefore an object glass of
forward, and the whole sail four times the area would be required, ie, of twice
lie more or less edgeways to the diameter. From this it will be understood, that
the wind, as in Fig. 3. To the power to be used must vary directly as the aper-
prevent this occurring, how-ture, and not as the area of object-glass, as
ever, in any but heavy gales supposes.
Hugo
or strong gusts of wind, I
S. T. PRESTON.
should weight it at GG, and
also perhaps have a cord run-
ning from G to K and M (Fig.
2), with a weight attached to
it as before.

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SIR,-" Derf Errac," page 657, reminds me of a promise of information as to Carié's improvements in electrical machines on the inductive principle. I have not happened to meet with further particulars than those he gave or referred to, and they are by no means clear and comprehensible; and I have had too much on my hands to make experiments, especially as I feel very doubtful if the matter is of much value. If "D. E." has not the number, he should obtain No. 226, which contains a description of Holtz's machine, on similar principles. I have tried vainly to get a sight of one, but none of the instrument makers appear to think them worth troubling themselves about. In reference to the brown paper machine, I do not think my remark was calculated to raise the querist's hopes unduly, and I quite agree with "D E." in what he says, it would be a very poor investment of the sails at B (Fig. 2) would of course be to have them A better, but more expensive plan for regulating time and labour. I expect a great drawback would made with movable weighbe the hygroscopic nature of the paper, which is not a very good non-conductor in consequence. ted fans, as in the ordinary As to the ebonite disc, I hope "D. E." will get off better than I mills. patent sails" of vertical did. I ordered a 15in. one, and was charged 178. 6d. They would then for it, though weighing barely 2lb., the seller declaring close at A on the open in a high wind at B, he had to get it from Germany. Flat sheet ebonite, side of the sail being presay in. thick, can be got and cut to size without diffi-sented to the wind, and thus culty, and the price is about 38. 6d. per lb., while the cause the cord and weight, cuttings from the square would be valuable for mak- Fig. 1, to come into play." ing up other instruments. For an induction machine a much smaller plate would do; and as there is no strain on it, only sufficient thickness is needed for maintaining its form.

HORIZONTAL WINDMILL.

SIGMA.

SIR, Seeing that the subject of windmills is being ventilated in your paper, I send you drawings of a horizontal windmill which I have designed, and which may perhaps be useful to some of your readers. Fig. 1 is a horizontal view, and Fig. 2 a view of it as seen from above. The letters are the same in both figures. The sails as shown at A, Fig. 1, are fixed loosely on to the levers, so as to permit the upper half to fall forward until horizontal, as shown at A', when the lever itself keeps it from further depression: neither can it go farther back than a perpendicular position. The sails are not fixed on the levers exactly in the middle, but, as shown at A, Fig. 1, the upper half is larger than the lower. fixed on near the end of each of the levers, round B is a pulley which a cord runs which is fastened to the top of the larger halves of each of the opposite sails. Fig. 2

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shows the position and working of the sails when in operation, the wind blowing in the direction indicated by the arrows. At A the wind has the greatest power, the sail being in a vertical position. Soon after passing A2 the last pressure of wind on the sail will cause the upper half to fall backward at the same time by means of the cord fetching up the sail at A4 to a vertical position, the wind itself forcing it up immediately it is raised above a level; the opposite sail or the wind indicated as A being then in the position shown at A3, the wind has no power at all. The levers can be shortened to suit the power of the wind, as the inner part, being hollow, permits the outer to be pushed into them and fastened with a pin at C. I have made one similar to this on a small scale, which works admirably. I think great power could be obtained by this machine. Next week, with your permission, I will send you drawings of another windmill, by which I think still greater power could be obtained, and which would be admirably adapted for working ship's pumps, as on board ship there is generally plenty of wind at man's disposal, but which is seldom made to perform those duties besides propulsion, which would be the saving of trouble and expense to the owner.

A RUSTIC FROM BERKSHIRE Downs.

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have never tested the above plan, nor indeed any
other. My model has no regulator. H. ALGAR.
might be used to catch the sails. The springs should
P.S.-Instead of cords and weights, steel springs
of course be strong enough to
resist an ordinary wind, and
weak enough to yield to a
gale. The sails should be
much larger than I have re-
presented them either in this
or my former letter. If there were four sails, one
cord only would be in tension at or about A, Fig. 2,
at any one time. If there were eight sails, two
weights would be needed, and cords 1, 3, 5, 7 must be
tie i to weight No. 1, the others to weight No. 2.

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I must apologise if I have at all infringed Mr. Vallance's patent, but at present do not understand very exactly how far our plans agree. Would Mr. V kindly send a side view of his mill, with sails and spring ready for action?

I have never made any use of mine except as a motive power to a small model raft fitted with paddle wheels. I thought it possibly might be employed to force a vessel against the wind. Clumsiness of work manship, however, and disproportion between sails and paddle-wheels prevented my arriving at any decided opinion on the subject.

I have known my mill revolve with only one sail up, but fancy it would do so only in a high wind, my model being too small and ill-made to admit of much

momentum.

H. ALGAR.

VIOLIN VARNISH.

ENGLISH MECHANIC, signed "B.," inviting discusSIR,-A week or two ago a letter appeared in the sion on the subject of violin varnish; but although it readers, "B.'s" letter has not at present elicited any and of interest to a considerable number of your appears to me a subject eminently worthy of attention, reply. I venture to write this letter in the hope that the subject may be re-opened by attracting the attention of some of your chemical subscribers or others, although they may not themselves be directly interested in the construction of the violin.

The requirements of a good violin varnish are, that it should afford protection to the wood, but at the same time it must not interfere with the vibration of the instrument. M. Grivel, who professes to have re-discovered the All the ordinary varnishes made since they do not allow the wood to vibrate freely. from gums and resins are quite unsuitable for violins, old Cremona varnish, says that not one of the substances used in ordinary varnish is used in compounding it, and that it is a spirit varnish. If this latter assertion is true, it upsets the generally received opinion that the Cremona makers varnished in oil.

There are many who insist that the sole cause of the superiority of the Cremona instruments is the warnish with which they are covered; but although no one who has studied the subject properly will hold this idea, no one will deny that the varnish is of very great importance; and any hints in the MECHANIC would be highly interesting to many.

In conclusion, I may suggest a method by which the fitness of a varnish for musical purposes could be tested. Two thin slips of the same wood, and of the same dimensions, if made to vibrate in the same mansion-will render the same sound. Now, if one of two ner-that is, made to produce the same nodal dívisuch rods be covered with the varnish under examithe effect of the varnish will be at once apparent. If nation, and then both rods be caused to vibrate again, the varnish be bad, the covered rod will give a lower sound than before; but if a varnish could be found that could be applied to the wood without lowering the sound, or, in other words, without interfering with free vibration, the desired result would be obtained. J. T.

HOW TO MAKE AN ERECT DECLINING
SUNDIAL.

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SIR,-I am not about to repeat in this letter what has been offered in a former one, and for those who wish to know what an erect declining sundial is, I page 460. My object now is to state the method of will refer them to No. 252 of the ENGLISH MECHANIC, constructing such a dial by the terrestrial globe, which way to working it out by trigonometry and logarithms. may be of service to those who prefer doing it this place, may be made upon the principle of a horizontal All sundials, whatever be the declination of the dial, if we only know the latitude and longitude of the place to which the declination of the plane some particular country; and in declining dials, the answers, for all are constructed for the meridian of from our 12 o'clock line is, because the country where reason of the substiler line being at a certain distance it would be a horizontal dial has the time earlier or for instance, we all know that the time in Africa it later, according to the declination of the plane. Thus, the Cape of Good Hope it is 12 o'clock at London; consequently the sun will come to the meridian of any later than in London; that when it is 1hr. 16min. at place in that country sooner than here. Suppose the "F.R.A.S." AND THE NAUTICAL ALMANAC. plane on which we construct our dial decline from the N. towards the E. 63°, we shall find by the globe cerning the tables of Jupiter's satellites, that appear the S. towards the E., and having made a mark on the that such a place corresponds to a place near the S. in the "Nautical Almanac," "F.R.A.S." has employed globe where it touches this point on the wooden SIR, In answer to a query from "Equatoreal," con- point on the wooden horizon, which will be 27° from coast of Africa. We must first count 90° from that language which, I think, is susceptible of misconstruc-horizon, we must bring it to the brazen meridian, and tion, as it may be thought to censure the authorities then we shall find its latitude and longitude. We tbat publish the "National Ephemeris." Almanac," is to accurately deduce certain results from under the brazen meridian. We shall then find the certain tables, and the predictions concerning the latitude to be 35° 40′ S., and the longitude 330 E. The The business of the computers of the "Nautical the latitude 51° 30', and the meridian of Greenwich must remember, however, to have the pole elevated to phenomena of Jupiter's satellites, are in this respect difference of time, therefore, is 2hr. 12min. ; but as it remind "F.R.A.S., that the use of an ephemeris is from our dial, we can arrange the hours for the latinot only to enable astronomers to observe certain phe- tude of London in the following way: Keeping the as accurate as any other part of the work. I will would be very inconvenient to subtract this amount nomena, but to enable them to make comparisons be-globe elevated, we may pass a thin strip of brass tween the assumed theory and the observed fact, and so across it graduated to 180°, or a thin tape would to derive the amount of correction that must be applied answer the purpose-one end of it must be placed on with the observations; and when the elements of declination. Thus, we must bring one end of it to 630 Jupiter's satellites come to be re-discussed, the dis- from the N. towards the E.; we must then pass it to the elements, to bring the theory in accordance the wooden horizon exactly at the degree of the wall's cordances between the predictions and the observa- under the brazen meridian across the zenith, which, vations, will be of the greatest use, and the accuracy as the globe is elevated, will be 383° from the Pole,

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TURNING BUNGS WITH A FOOT LATIE
SIR-I bought a small foot lathe about a month
ago for the sole purpose of turning bungs. The size
of it is 31 centre, with a 2 2 fly wheel. I have
spent a considerable amount of time in trying to find
out a plan by which I could them (the bungs) speedily,
and tried three or four different ways without, I may
say, any success. I have no doubt there is a proper
method, if I only knew of it, by which I could turn
my want of mechanical skill in asking a question
them with great speed, and fear I am only exposing
which I have no doubt is simple enough to the
initiated. I shall be very thankful if you or any of
the readers of your valuable journal can tell me of a
good plan or instrument by which I can accomplish
my object.
P. KENNY.

TURRET CLOCK.

SIR-Will you kindly allow me to ask Sidney Maddison if be will explain the manner in which the hour and quarter trains of his clock are discharged, and also to explain the winding more fully, and how the motion work is worked. Can the

A GOOD INSTRUMENT.
SIR,-"G. C." mentions my name in the ENGLISH
MECHANIC, as the possessor of a 4in. Alvan Clark,
and which he very justly, I think, describes as a fine
instrument. I have only had the instrument some
two or three months, but have used and tested it a good
deal in the time. It seems very perfect in both stellar
and planetary definitions. It will clearly divide e
Arietis. Orionis it appears to separate, but the
smaller and dull coloured star is a little flattened. y
Andromeda is elongated, and also Cancri, slightly
I think; but in this case I am speaking from only
one observation. The following minute, stars I have
seen with this glass:-The 5th and 6th stars in trape-
zium; the 6th about three or four times in the last
two months; the faint companion to A Orionis, as a
steady object, and with all powers; the 15th magni-
tude comes to 52 Arietis on three occasions, steadily,
with 130 power; T. Orionis, with nearly all powers; 15
Monocerotis quadruple. The small stars in Sigma,
Arionis, and the 11th magnitude star, companion to
A Lyra, are not "put out" with a power of 400, al-
though are of course not so well seen as with a much
lower power. I have seen six specks, or craters, on
the floor of Plato. Jupiter and Venus I have seen
beautifully defined. I have an achromatic eye-piece,
giving a power of about 500, and I have seen with this
power Venus defined really wonderfully well.
Jupiter wants more light, and I have generally found
220 high enough. The outline of the disc is sharp,
with any power, but with a high power there is not
sufficient illumination to show the fainter belts. There
is a peculiarity about this O.G. which I never met
crown lens, are worked to the same curve, and either
with before, and that is, that the two surfaces of the
surface seems exactly to fit the concave flint.
trying the telescope I found the O.G. would per-
form wonderfully well with crown lens, turned
either way, and it took me some little time be-
fore I became satisfied which was the best position
for the crown lens. I find with crown lens, placed in
one position, the O. G. will not bear a ring aperture
so well as in the other position, but with the full
aperture, definition is very good, and this is the posi-
tion in which the lenses were placed when I received
the O. G. (second hand). My experience leaves me to
prefer the reversed position of the crown lens. I had
an opportunity of looking through "G. C.'s," tele-
scope, 24in., mentioned in the MECHANIC, and I find
I am an unbeliever in
it gives very small star discs.
size of star discs, varying with aperture alone, irre-
curves of object glass.
spective of the focal length and figure of speculum, or

W. MATTHEWS, Hill House, Gorleston, Yarmouth.

-

BREAD MAKING.
SIR,-I should feel obliged if any of your readers
could give me a good recipe for the making of yeast
or barm. It is sometimes difficult to get it from the
brewers, even in the country-I mean in remote
places, and in London you can't get it all, and if you
wish to bake your own bread, you must put up with
baking powders. For my own part, I don't believe
they are wholesome, and am afraid they leave an in-
jurious deposit on the system, if long used. Besides,

What is wanted is a simple yeast that will act on flour like brewers' barm, and that can be easily made by ordinary person, good bread from powders or German yeast being an impossibility to those who know what bread really is.

SIR, A correspondent in your paper has, through your kindness, asked instructions and dimensions to help him in constructing a cross-bow. I enclose a drawing of one I some years back obtained of an old family in the New Forest, where they were used to shoot deer and rooks until a late period.

A is a piece of iron in which to place the toe of the foot whilst stringing. B B, two iron braces, connecting this toe-rest, the steel bow and stock, as shown in No. 2. CC, the steel bow, 14in. in width at top, graduating, from the bend to each extreme, to in., having a fork to receive the bowstring. D is a groove of smooth horn to facilitate the slide of arrow. a bone sunk in the stock of the bow, on which the trigger acts, to keep it strung. It is of circular form, projecting above the stock of the bow, and is grooved. When the trigger is loosed, this bone turns and propels the arrow, shown at A No. 2. F are strips of

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E is

iron to strengthen the stock and keep the bone to
place, having a transverse pin on which to rest the
instrument, to claw the string back over the bone E.
G, an iron lozenge pin, with two bone pins for sight-
ing. No. 3, the instrument to claw back string HH,
pass each side of stock behind the F transverse in the
drawing of crossbow. II. two claws put to the
string of bow, when the handle J is drawn back, and
brings the string to shooting position. B No. 2 is &
piece of iron similar to the guard of a carving fork,
and keeps the trigger to place. When this is pushed
forward, the bone A passes round, and the string
The bow steel is in.
released, propels the arrow.
thick. The string must be a very strong tendon of an
animal, or bullock twistle. The stock is 2ft. 24in. in
length.
F. B. ARGYLE, Christchurch, Hants.

clock be seen in action; if so, where and at what time?the bread made in this way is not light, neither is it tion of mine for preventing those deplorable accidents

COMPENSATION.

POISONOUS POSTAGE STAMPS.

SIR-I went to see a friend of mine one night last
week, and, much to my surprise, found him suffering
from severe vomiting, as he seemed quite well when I
saw him at noon of the same day. I asked the cause
of his sickness, and he informed me that he had been
despatching a quantity of circulars by post that
evening, and that the gum-or, better, the "glutinous
concoction"-ou the back of the penny stamps had
made him very sick.
Now is not this too bad? It
almost makes one shudder to think what this stuff is
composed of; and we know for certain that some of
it must pass down the throats of stamp users. There
are many "pretty, patent" little devices for wetting
postage stamps, but how many use them? We can
safely say that 99 out of every 10 stamps consumed
in the kingdom are wetted with the mouth. The
higher priced labels are free from this concoction;
so also are the stamps of the Inland Revenue Depart
ment. What excuse has the Postmaster-General for
this?-surely not expense, seeing how small the pro-

heavy and (no matter what pains you may take in
mixing) it is anything but satisfactory. I have tried
Liebig's method, Borwick's method, hydrochloric
acid, carb. ainm., carb. soda, &c. but they are really
failures, and not equal to bread made with brewers'
yeast. Liebig's mode is the best, but still the bread
is not sufficiently light. Borwick's powders any one
can try, as they are sold at many places, and are
panegyrised from day to day. I have found them in-
effectual, but for those who are not particular the fol-
lowing form is perhaps as good as any, and any per-
son can make it for next to nothing, the cost being
very trifling; Ground rice, 11b.; carbonate of soda,
1b.; tartaric acid (crushed very finely), 6oz. To be
kept in a dry place, in a stoppered bottle, or well
secured from the air. Use it like other baking pow-
ders. A good sort of yeast is made in Hungary from
bran, and I believe the Persians use pease (which are
windy) for the same purpose, but I am ignorant of the
process. Teetotal barm is made of potatoes, flour,
hops, and brown sugar, quickened, I think, with
brewers' yenst. Cobbett recommends a kind of cake,
made in summer time, of rye flour, but the process,
although satisfactory, is inconvenient.

GUN ACCIDENTS. SIR,-As a humane man, you will, I am sure, insert the following description and drawings of an invenresulting from the unintentional discharge of firearms. Such accidents are almost invariably caused by the cocks becoming caught in hedges, bushes, etc., or by the gun being carelessly or ignorantly carried at full cock, when, of course, any accidental touch on the trigger fires the piece, and the result is frequently wounds or death. My invention is simple, strong, and inexpensive; can be attached to any gun-locks, makes guns much safer, prevents wear of locks, and removes the necessity of always bringing the gun to "half cock" before crossing hedges, walls, etc. merely add that having no pecuniary interest whatever in the invention, and not having patented it, all persons are at liberty to use it. A the cock, with the notches BBB cut or filed on its front edge. C is n steel catch, with a square hole through it, into which D, a milled boss or button, the boss or button D'fits. countersunk at the top to receive a small screw and It has a hole drilled through it to admit a washer. stout steel pin, upon which it turns, and which is rivetted to the lock plate. E is a small, short steel peg, also rivetted to the lock plate, to prevent the catch C from going below the lowest notch B in cocking, and to support the cock if the trigger should be

I

[MARCH 25, 1870.

the Füstenwald lignites. The components of the gas at a specific gravity of 0.5451, is said to be as follows:

accidentally pulled. FFF are screws to fasten the cover or cap H to the lock plate. K is an ordinary V spring. The notches on the edge of the cock need not be cut quite across the edge of the cock, but the face of the cock can be left unaltered, so that the notches may be unseen. Of course C and D may be made in one piece, if preferred. H is a cap or cover made of stout sheet-iron, case-hardened, or of thin steel. some locks it will be necessary to place the guard in In the rear instead of the front of the cock. In that case it will only be necessary to invert the guard and cut the notches in the rear of the cock. To set the guard, turn the boss D towards the cock, and to throw it out of gear, turn it from it. invention, and find it never fails. I have severely tested my B is for full cock, another for half cock, and the One of the notches upper one is for securing the cock in case it should be accidentally lifted. I sincerely hope that the Baines safety guard may be of service to my countrymen, and that it may be the means of saving human life.

HENRY D. BAINES.

DRAWING FOR THE MILLION-No. IV.

SIR, -T. 1 to 4.-Continuation of cylinders and cones. Many figures are combinations of cylinders and cones. Draw always first the enveloping prism, the great outlines. Generalise your exercise, put the solid in other positions: p. ex., horizontally instead of vertically, &c.

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in your pages of late. To threw some light on the
controversy, I beg to send an extract from an Ame-
rican paper, which has recently been sent to me by a
friend on the other side of the water.
AN OLD SUBSCRIBER.
ferent ways has been introduced, and doubtless this
"During the last few years heating with gas in dif-
plication on account of its cleanliness and simplicity,
mode of heating would enjoy a far more extensive ap-
the one hand, and the impracticability of generating
were it not for the high price of illuminating gas on
gas on the principle of Sleman's gas generator, on a
small scale, on the other hand. The supply of a cheap
article, seems, therefore, very desirable; and this ob
now building at Fürstenwald, near Berlin. The gas
ject, we learn, is about to be realised by the gas works
is to be generated from lignites at Fürstenwald,
about 22 miles from Berlin, and carried to the
latter city by means of pipes.
there will be erected at Fürstenwald 12 buildings, each
105 by 62ft., with an aggregate of 70 furnaces, each
containing 10 retorts. The furnaces will be provided
with Sieman's regenerator.
condensers, is brought to Berlin through a series of
been freed from tar, water, &c., by passing through
The gas, after having
pipes, 4ft. in diameter, into which it is forced by
cylinder-blasts of 7ft. 73in diameter and 6ft. stroke.
The blasts are propelled by 4 steam engines of 6ft.
stroke, and 360 horse power each, capable, however,
of working up to 500 horse power. The pressure of the

4

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Carbonic oxide

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11.37

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Nitrogen

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Carbonic Acid

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Carburrêtted hydrogen (conden

If this composition of the gas can be regularly maintained throughout, it will answer it purpose perfectly. The experiment shows that 3000 cubic feet of the gas are equal in heating power to one ton of lignite, or one-third ton of hard coal. rated at 12 cents gold per 1000 cubic feet, and the The price at Berlin is equivalent of one ton of hard coal will cost in Berlin 1 dol. 12 cents gold. The capacity of the works are calculated at 9,500,000 cubic feet per annum, or about 10 millions per day, which it is said will cover the demand of about half the city."

THE WORKING OF GRANITE IN ANCIENT
TIMES.

questionable if it is wrought more beautifully than it
the lathe, and polished by machinery, but it is very
SIR,-Granite is now commonly planed, turned in
of what patient labour can effect, but India, from
whence it is probable Egyptian civilisation was
derived, yet possesses monuments of early human
was by hand in ancient times. Egypt shows examples
skill, which are hardly equalled by any extant
India (probably at least as old as the Egyptian pyra
mids), originally consisted of seven lofty walls, six of
examples of Egyptian art.
The famous temple of Chillambrum, in Southern
them within the external one and each within the
other, surrounding the central quadrangle. These
mids, forming a huge cross, probably by no means the
walls had seven gateways and twenty-eight pyra-
fr. Mutheran, appear to be far more ancient. The
figure, for the crosses discovered in Central India by
earliest example of that most universally distributed
walls of this temple extended over a mile in one
direction, and have never, that I know, been equalled
in magnitude by any modern Christian structure

of chains, depending from pilasters; each of these
The interior of this temple is decorated by festoons
chains was wrought out of a single piece of granite,
sixty feet long, the links, twenty in number, having
been carved, intersecting each other, and highly
polished; indeed they retain their polish to this day.
Each link is thirty-two inches diameter, and I am
told, only one is broken; and much as I dislike the
desecration of ancient monuments, I should like to
see a few links of the broken chain in the British
Museum, for an example to English mechanics. I
cannot help thinking it rather doubtful, if our auto-
matic granite working machinery could do much
better than these people of the same Aryan race as
ourselves did by hand, it is said, without steel tools-
but this I beg leave to doubt-notwithstanding Sir
J. Whitworth does deservedly esteem its powers so
highly.
THE HARMONIOUS BLACKSMITH.

VERY REMARKABLE ANCIENT MUSICAL

INSTRUMENT.

This

SIR,-In an ancient Peruvian huaca, or catacomb, a syrinx, or Pandean pipe, was found, which was carved out of a solid mass of lapis ollaris. This interesting relict of an ancient and extinct civilisation (which may be as old as the representations of harps found by Bruce in the tombs of the kings of Egypt, an engraving of which is in Burney's "History of Music "), is profusely ornamented with representations of what are termed Maltese crosses, a thing not very surprising when it is considered that the cross is perhaps without exception, the most ancient and widely diffused of existing symbols, both in the Old and New worlds, for it is found throughout Europe, Asia, Africa, America, and even the islands of the Pacific, Tonga, Viti, and Easter Island for instance. instrument is also ornamented by other symbols, very similar to those found on Egyptian obelisks, and on some of the monoliths met with in Western Europe. An engraving of this remarkable specimen of Pan's pipe, is in the Trans. Roy. Soc. Edinburgh," Vol. 20, page 121. Query, does not its ornamentation indicate (in common with the almost identity of ancient architectural remains in India, Java, the Pacific Islands, and South America), the intercommunication of the ancient races of mankind, which inhabited the Old and New Worlds, perhaps before the Pacific Ocean was formed, or at least before a large extent of land between Asia and America was submerged? THE HARMONIOUS BLACKSMITH.

LOCK NUT.

U.-Cone cut by two planes passing through the gas in the pipes is intended at 16ft. water, equal to and on the inner plate a small square groove, cut

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the pipes, and seems to offer a lower one in many
tively high pressure allows or a smaller diameter of
about 71b. to the square inch, since this compara
boiler plates, and
ground, to render them at any time easily accessible,
other respects. The pipes are to be made of in.
not buried,
pillars.
but laid above
and supported in an appropriate manner by stone
will deliver 407 cubic feet per second.
Under a pressure of 16ft. water, the pipes
At Berlin the gas will be stored in 12 gasometers,
each 1541t. in diameter and 40ft. high, having,
therefore, a capacity of about 750,000 cubic feet. From
these gasometers the city is to be supplied. From ex-
periments made by Dr. Zuirck, of Berlin, it seems
that a gas of good heating quality can be made from

SIR,-In our valuable paper for February 25, page 575, there is an account and drawings of a patent lock nut for the joints of railway rails. I think it would be too expensive for railway work, and propose a lock nut for joints of rails in this form; the head of the bolt made to fit in an oval hole, so that it will not turn, squares of the nut, but at the back, so that when the across the centre of the hole, aud a cut similar in the and long enough to get hold of it to take it out at any the groove in the plate, there remains a square hole nut is screwed home, any of the squares put opposite for a key to drop in, but not to be made to fit too tight, time, so that when the plates wear, take out the key and you can either give it a quarter or half turn, level, then put in the small iron key, and it will whichever it requires to tighten it, so that the nut is remain firm until wear takes place. If too expensive for main roads, it would prove valuable for points and crossings in yards, especially for junctions. Let some of our brother correspondents give me their opinion of it.

PLATELAYER.

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FIG. 2

FIG. I

FIG. 3

KAPPER'S IMPROVED FIRES.
SIR,-I send you above a rough sketch of Mr. Kapper's
improved fires, which he has introduced into Chat-
Fig. 1
ham Dockyard, with a saving of 50 per cent.
is for welding tabes. The sketch shows the working
of it. When it welded the shaft tubes for the Glatton
the tubes were 13ft long, 4ft. one end, 2ft. 6in. the
other. This fire is well adapted for boiler-makers, for
welding the inner tubes. Fig. 2 is more for beams,
plates, or angle iron. It is a very valuable fire.
easily lighted or easily cleaned out; there is no turn-
ing the work on edge. Fig. 3 is for heating the arms
of beams for bending. We are able to bend an arm in
one heat. I think the sketch needs no explanation;
but if any of the readers wish it, I will be most happy
to give it.

It is

GEO. HUART, Franklin-road, New Brompton.

EXTRACTS FROM CORRESPONDENCE.

and Pharmacy, &c."

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"

HINTS TO CORRES-
PONDENTS. - **Scruta.
tor Bay's" G. Forrest
(p. 636) recommends Scru-
tator to sign himself
'Screw Loose,' or screw
tighter his ideas before he
rushes into print.' The
force and real application
of these remarks will be
seen by reading further on,
where he says-" Gitche
Manito" is quite right in
saying that the machine
used for shoddy manufac-
ture is called a "willey,'
or vulgarly a "devil.'
Now it so happens that
Gitche Manito' did not
say anything of the kind.
The expression vulgarly a
devil was my own! From
this I infer that G. Forrest
did not quite understand
what he was writing about;
I beg, therefore, to include
him with those to whom,
Hints to Correspondents'
are intended to apply.
Gitche Manito,' whose
letters are most fully ap-
preciated by me, will, I am
sure, see the folly of G.
Forrest 'rushing into
print. With regard to G.
Quilosa's more respectful
letter, I beg to remark that
if, after 25 years' experi-
ence in teaching, he will
inform me through the
pages of our MECHANIC
that he is not sufficiently
up' in the subject of Pro-
jection to detect the erro-
neous teaching in the book
he so strongly recommends
('Projection,' by Ellis A.
Davidson), I will, through
the same medium, endea-
vour to enlighten him, al-
though I have no inten-
tion of reviewing the work in question."
CONSUMPTION.-" Hanley" states:-"I am glad
to see you take so much interest in that terrible com-
plaint consumption. Some years ago, a relation of
mine travelled amongst the Portuguese, and the
country-people used the following plan for all lung
diseases, in the first stage.-New milk one quart, then
take a flat bar of clean iron about 1in. thick, make
it a bright red colour in the fire, then stir the milk
with the iron till you have reduced the quantity by a
half a pint; this is taken every morning till the
patient gets better; they very seldom give drugs of
any kind. Perhaps some of your medical correspon-
dent can enlighten us what is the chemical action of
iron and milk on a diseased lung."

ད::

MEDICAL OPINION.-"F.R.C.S." writes" to beg to add a further remark on the question of improvement of your journal, and I venture to do so solely on public grounds, it is to caution correspondents, both those who make and those who answer medical questions at various times. I have noticed inquiries and replies calculated to lead to great mischief; I might particularly indicate some relating to the sight and diseases of the eye. I am myself the chief surgeon to one of the large eye hospitals, giving advice to upwards of 10,000 patients annually, but I would not venture to reply to some of the questions as pounded in your columns."

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REPLIES TO QUERIES.

[1507.]-SEA VOYAGE.-Seeing that no answer appeared to this query, I extract the following from the "Annuaire de la Maison de Melle-lez-Sand," circumnavigation in 1870. The establishing of the steam boat lines between Australia and San Francisco (1866), and between San Francisco and Hong Kong (1867), has completed the circumnavigation by steam. Those two lines present but a little difference as well as to the price of passage as to the duration of the voyage. Prices are the following in first-class (I reduce approximatively in English currency), from Paris to Marseilles £4, from Marseilles to Alexandria £20 128., from Alexandria to Suez £2, from Suez to Aden £40, from Aden to Pointe de Galle (Ceylon), £40. At Pointe On the northern one de Galle the two lines separate. we pay from Ceylon to Hong Kong £30, from Hong Kong to San Francisco £60, from San Francisco to Saint Nazaire, (France), £70, on the Panama Railway On the south£5, and from St. Nazaire to Paris £2. ern line from Point de Galle to Sidney £50, from Sydney to Panama £60, for Panama Railway £5, from Colon or Aspinwall to St. Nazaire £44, and from St. Nazaire to Parls £2. The whole voyage costs:

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By Hong Kong, 1st class, £263 128.
By Australia,
£257 128.
The duration in time is the same.
Days.

Days. 25

Paris to P. de Galle... 25 | Paris to P. de Galle
P. de Galle to Sydney 24 P. de G. to Hong Kong 15
Sydney to St. Nazaire 55 Hong Kong to S. Nazaire 64
Total

Tetal

104

104

By the opening of the Pacific railroad, the Australian line comes in the second rank. The shortest ronte round the world is that of San Francisco; by this line one can go in 39 days from Liverpool to Hong Kong, and the whole tour requires only 80 days.—CAMILLE, D. P.

[1651.]-LOCKS.-There is a book on this subject, "Construction of Door Locks," to be had of Virtue Brothers and Co., 26, Ivy-lane, Paternoster-row.MATY.

[1729.] RINGS OF STEAM.-Any force acting suddenly upon the air from a centre imparts to it a rotary motion, which is not only confined to loco's and baccy pipes. If a big gun, on a still day be fired, without shot, with a well greased muzzle, an enormous and regular smoke ring will be the result.MATY.

[1798.]-VARNISH.- Mr. B. Nicoll's address is Regent-c reus, Piccadilly; and his works, No. 11 Arch, Lachmere-grove, Battersea.-A. M.

[1799] REVERSING ECCENTRIC.-I cannot do better in this instance than quote Rankine :-" To reverse the direction of rotation of the shaft of a steam engine, the piston must be made to come to rest and then to move the reverse way, before completing a stroke, and the eccentric must assume that position relatively to the crank which is proper for working the slide valve when the rotation of the shaft is reversed. That position (or the position of backward gear) is somewhat less than half a circumference from the position of forward gear, measured round the shaft in the direction of forward rotation. To bring the eccentric, therefore, into backward gear, it is sufficient to cause it first to stand still while the shaft nearly finishes the first halt turn backwards, and then to accompany the shaft in its rotation. In most stationary engines, and many marine engines, those objects are effected by having the eccentric pro-centre of gravity shall be in the axis of the shaft, but loose on the shaft, and so counterpoised, that its prevented from turning completely round by means of two shoulders, one of which holds it in the position of forward gear, and the other in that of backward gear, care being taken that the motion of the loose eccentric round the shaft shall be forwards to go from forward into backward gear, and backwards to go from backward into forward gear. To reverse an engine with a loose eccentric, the gab is to be disengaged from its pin and the slide valve moved by hand if necessary. When the shaft has made part of a turn backwards, a stop on the shaft comes against a shoulder of the eccentric causing it to assume its motion, re-engaging the gab and working the valve as before.-MATY.

STARCH.- H. E. Godfrey observes:-"I was
delighted with the interest taken in the subject
starch. Long live our journal of mutual instruction!
Much good might be done among pharmaceutical
MANGANESE BATTERY.-Mr. W. H. Stone
students by short notes on Materia Medica, Botany, deprecates the imperfect information which has been
given since we inserted his detailed account a short
WATCH CLEANING.-" Ab-oth-Yate "writes:-
time since. He says:-"The strong saline solution,
"To Veritas, Stopt,' and others. The olive oil spoken of in the last number, is best formed of satu-
purified with lead shavings is very good, but if they rated solution of sal-ammoniac. No perforated shelf
will purchase the best almond oil, they will find it
to hold a supply of salts' is needed; at least mine has
much better, as it does not gum nor freeze like the been working untouched for seven months without.
best purified olive oil does. Tried and found good."
A cylinder of amalgamated zinc open at top and
THE USES OF OLD HORSE.-H. E. Godfrey, bottom' is equally needless, as a small flat strip 2in.
referring to a letter under this head in our last number broad answers any purpose, and costs much less.
says: It may be interesting to some of the readers Lastly, there is no need to give 78. or even 58. for
A quart jar costs 6d, a 6in. porous
of the ENGLISH MECHANIC who have a passion for each cell.
ketchup, to be informed that there are establishments, pot 7d., a carbon to match about 18., zinc about 2d.,
in and about London, devoted especially to the pre-sal-ammoniac lb 3d, manganese about 1lb. 2d; total
Of course binding screws and platinum con-
paration of genuine mushroom ketchup from old 28. 8d.
horses' livers, which are allowed to decompose for the nections are expensive, but there are simple means of
purpose."
dispensing with both.

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ON SKETCHING FROM NATURE.-"Mus
A RARE LENS. The largest photographic por-
says:-"May I make a remark or two on the above trait lens ever made in this country is one of 10in.
Japers? At line 7 from the bottom the writer says,diameter, recently completed by Ross, and now in the
Hence it is always,' &c., &c.
He should have possession of Mr. Mayall, of Regent-street. It is an
explained that if an appearance of height is to be achromatic lens of great power, and will take por-
given to a building, in the foreground especially, the
traits of any size, from the smallest miniature up to
perspective must be attended to. For instance, in
very nearly life size. It is made of glass of the whitest
Fig. 1, standing at the foot of a house, the perspective description, and its size admits so large a volume of
causes the line of the roof to slope as in diagram, and. light that photographs covering a space of 10in, by 12in.
as the writer himself states and shows, not only the
may be done in eight seconds. The lens renders in the
proportionate height of the house, but also its posi
Photograph all that is seen in the optical image, and
tion. In the same Fig. we have, on the opposite side
this so truthfully that the coarseness and exaggera-
a smaller house, hence the difference in perspective tion belonging to large photographs taken with
The only method we have of showing the stupendous
inferior lenses are altogether absent. In the open air
height of such towers as St. Peter's at Roine, and
<roups of 15 to 20 persons (each face about the size of
Strasbourg Cathedral is by the perspective. Proof o sovereign, and the whole picture 24in. by 24in.) can
this may be seen in a lithograph of the latter church, be taken with the short exposure of 10 seconds. The
by T. M. Richardson, jun."
cost of manufacturing the lens was upwards of £200.

[1809.]-FEATHERS IN WOOD.-The following which recently appeared in the Builder, will answer

"E. R. S. :-"In the structure of all woods used in

building, there is, firstly, a series of vessels of woody
tissue surrounding the heart of the tree, having a verti
cal growth, and arranged in annual concentric circles;
secondly, there are certain hard woody growths,
called the" medullary rays," radiating from the heart,
and consequently more or less horizontal: these
vertical and horizontal growths are intimately but
regularly plaited and intertwined together, to give
strength to the trunk, and thus far all is regularity.
Now where the branches burst through the stem this
regular arrangement is upset, and the above-mentioned
woody vessels are disarranged, and pushed at different
angles. When the tree is cut down and sawn hori-
zontally across amongst these branches, these dis-
rupted horizontal and vertical vessels (of different
colours, be it remembered) are seen cut at every con-
ceivable angle, and an ornamental feather,' more or
less extensive, is the consequence.
not exist at the base of the tree, because there are no
branches there to disturb the annual growths of the
wood (minute feathers do indeed exist at the very
heart, and these were caused by the growth of leaves
a seedling or little
and twigs when the tree was
cutting). Feathers are not seen in deal, because the
fir is a straight-growing tree, without branches in the
portion of the trunk used in commerce.
are seen most abundantly in pollards,' for the simple
reason that after the top of the tree has been sawn off,
an immense growth of branches is always induced,
disturbing the tissues in every imaginable way; the
adds greatly to
action of the light on the feathers
their beauty after the wood is polished.'-GIPSY.

These feathers do

'Feathers

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