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drawn off at the back, as represented at E. Into this loop the point of a shuttle, or the hook of a lockstitch machine, enters, so that the whole length of the under thread is carried through the loop; both sides being tightened at the same instant.

This application of needle and shuttle to a sewing machine was the invention of the late Elias Howe, Jun., of America, whose career as a mechanic is one of the most extraordinary on record. Maturing his invention kept him poor, and then he had to defend his rights at law, finally obtaining royalties from the American sewing machine makers which amounted to a very large yearly income, in addition to the large profits he made in the manufacture of the Howe sewing machine.

Fig. 5 represents the formation of the Howe or shuttle stitch, the upper, or needle thread a, laying on top of the fabric, and the lower or shuttle thread b. laying below the fabric, the threads being interlocked at cece with each other in the middle of the fabric between the four stitches.

It is the strongest stitch made, and cannot be rathe least quantity of thread, it is in general use, with velled. The stitch being alike on both sides, and using out complaint, unless badly made by an inferior machine, or an incompetent operator.

Fig. 6 shows a front side, and Fig. 7 an end view o a shuttle and needle, the arrows showing the direction of their movements when about to pull up a stitch and they are so timed or adjusted as to complete each on its stroke at the same instant, so that the shuttle pull forward, and the needle upward, giving a pull of th two threads in like manner to the shoemaker whe stiiching the sole of a boot.

R is the shuttle reel. After winding the thread ver evenly upon it by the machine, it is placed in th shuttle, and kept in a position by a spring or catch s as to turn freely. The thread in working off it directed from the underneath side to a hole in the bo tom edge of the shuttle passing outwards, then by hole adjoining it returns inward, then to holes in t front end, and to the outlet holes in the top edge the shuttle to the fabric. A spring in the front end the shuttle at T, with its screw to regulate the tensi or strain on the thread, gives the operator the powe in conjunction with a tension on the needle thread, interlock the threads in the middle of the fabric; if preferred, to pull one thread tighter than the oth according to the requirements of the work in hand. H is a part of the needle bar, into which the need is inserted and fixed by a screw I. In the return stro If th the needle descends through the fabric, the nee hole in the cloth plate, and into a slot in the metal parts are not truly fitted and well polished, t against which travels the face of the shuttle.

machine will be very troublesome, although the work-fitting is the reason for my liking my specimen so
manship of other parts may be very good.
A PRACTICAL MAN.

LATHES.

little as I do; whereas I do not, on the whole, think it anything like so good as the one I call mine, figured October 22nd last year (or Feburary 18th this year, with the addition of a shield for the hands), which I have been using constantly for 12 years, and cannot suggest any improvement in. The 4-dog-chuck is the SIR-In my letter on the subject of the Saltaire-king of chucks for everything above lin. diameter, and Wardour-st. lathe, you have altered my sense in the 24th mine the best for everything under that size. Universal line by inserting the word "cut." The cutting would be chucks, with right and left-handed screw, and 2 dogs the least part of the expense of steel wheels, as, when once only, are very well for amateurs, possibly, but are a forged and turned, the cutting would be done with no more difficulty in steel than in brass, only taking a longer delusion and a snare, and, I should think, not an effective snare for a practical man. Clements made time to accomplish. In the slide rest of that lathe there three of them, I believe, for his own use, and any one are several small wheels cut out of the solid steel, besides, of the three fitting interchangeably on four different if I recollect right, a rack for one motion, and a segment lathes in his shop. I am, as I say above, not a believer equivalent to a portion of a large wheel for another. in them, any more than I am in Clements's driver During the past week I have had to cut teeth of fin. pitch, chuck, which you find put on all high-class lathes, in. deep, and through cast steel fin. thick, which took 8 bound, as I must be, to admit that Clements was a minutes each to do, so the cutting, alone, of a set of wheels man of extraordinary talent and, perhaps, the best would not come to very much money, but I am not pre- mechanician of his day. pared to say where the necessary forgings could be got done, up to 9 or 10 inches in diameter, and soft enough J. K. P. to be cut at all.

RHEA GRASS. SIR,-The following information, which I copy from a contemporary, may be acceptable, supplementing as it does that given by "Minnehaha" in your last

number.

D. V.

"The great drawback which has hitherto prevented the utilisation of this grass has undoubtedly been the difficulty of extracting the fibre, the manual process being so expensive as almost to amount to a prohibition of fibre manufacture being carried on. During the last twenty years or so, a number of machines have been brought out for extracting fibre, but none of these have been considered entirely satisfactory. Up to the present time, the common mode of extracting the fibre from such plants as the aloe is by soaking the leaves in water till the vascular matter has become rotten, and then beating off this decayed matter from the fibre with a wooden mallet, or scraping it off with a blunt knife. This process is not only a slow and nasty one, but is attended with much waste of fibre; it also discolours, and, what is most important of all, weakens the fibre. At the London Exhibition of 1862, two American gentlemen, named Sandford and Mallory, exhibited a machine for extracting fibre from aloe, plantain, or pineapple leaves. This machine has been used in America, but would scarcely be found either sufficiently simple or cheap for the ryots of India, its cost being about £45. What is wanted is a cheap machine of simple construction, by which the fibre can be easily extracted; and we think it only due to those of our readers who have contemplated entering the competitive list for the above-mentioned prize to state that a machine, possessing, so far as our present iniormation goes, all the necessary requirements, has already been invented in India by Mr. Donald Cruikshank, representative of the Telegraph Construction and Maintenance Company. No preparation of the leaves is required for this machine; they are taken to it green, just as they are cut from the bushes, and in the wonderfully short space of two minutes, the fibre in the leaves is brought out stripped of vascular matter, and in admirable condition. The rotting process not being necessary with this machine, the deteriorations in colour, as well as in the strength and fineness of the fibre which follow upon the adoption of that process are avoided. A correspondent of an Indian contemporary asserts that the samples from Mr. Cruikshank's machine were "fine, delicate, and even; not one was cut or broken; and the material would readily fetch £50 a ton in the home market." Assuming that the efficiency and simplicity of the machine are equal to anything that is likely to be set up in competition with it for the offered prize, we very much doubt whether it is likely to be surpassed in point of cheapness. It is so easily worked, we are informed, that any native may be taught to use it in an hour's time, and its construction is so simple that it can be sold for 10 rupees (£1 sterling). We hope shortly to be able to give some further description of this machine, which, if equal to the opinion as yet formed of it, from its experimental results, seems calculated to meet a want which is not confined only to the fibre-yielding plants of Eastern

India.

CASE HARDENING.

SIR,-If I may, I beg to inform "St. George" (p. 54), that I believe Mr. Armitage's method of case hardening or complete hardening is not only new but that it is the best for engine and machine gearing. During 24 years' experience at some of the leading engineers, such a process has not been adopted. For two steamboat companies and an eminent firm of engine makers, I have case hardened the gearing of several pairs of vibrating steam engines, but not by the plan of immersion. If the granting of a patent to the gentleman would do him some good I verily believe that it would not do any manufacturer the least harm. By the process in question, would St. George "inform me what quantity of the prussiate of potash would be required to thoroughly harden a crank pin or a piece of iron of the following dimensions:-15in. long by 4 in diameter, and how many times the retort would have to be fed with prussiate of potash before the article would be ready for cooling?

R. E. T.

BENNETT'S CHUCK. SIR,-In reply to "I. N. G.," anyone accustomed to turning knows that a hammer is constantly used for setting work true in all sorts of chucks; this is no exception, but it is, perhaps, rather a weak point in this one that after you have got your work to run as true as may be with the help of the hammer, the big screw still wants tightening, which must, to some trifling extent, alter the setting of the work. In my description of the chuck on p. 41, 23rd line, the word that being omitted before" the ," makes me too willing to admit that defective

reason,

FRAUNHOFER'S LINES.

J. K. P.

SIR, I have a grave suggestion for Mr. Proctor's consideration, regarding the origin of the dark lines crossing the solar spectrum. They are generally supposed to be caused by the absorption of those rays from the body of the sun by its luminous atmosphere, which that atmosphere itself emits.

I do not like to be continually at variance in my opinions with the rest of the scientific world, but greatly doubt whether these lines have not their origin nearer home, and represent the absorption of those portions of the solar beams by the chemical action established in their passage through our own atmosphere.

ASTRONOMICAL.

T. A.

SIR,-1. I should be glad of an explanation of the
reason why, in Dietrichsen's Almanac, the time given
between the rising and southing of a star is four
minutes less than between its southing and setting. I
do not see what connection there is with the fact that
a star sets four minutes later every day.
2. Will F.R.A.S." kindly tell us how he succeeded
with the object glass he commenced some time ago?
3. Sir John Herschel states that "the total thick-
ness to be abraded from the edge of a spherical spe-
culum 48in. in diameter, and 40ft. focus, to convert it
into a paraboloid, is only 1-21333rd part of an inch.''
How is this result obtained?
FRANK FOTHERGILL.

THE SUNFLOWER.
SIR,-When I think of the many uses of this plant,
and of the great ease with which it is grown, I feel
surprised that it is not more largely cultivated. It
ought to be, if properly grown, far more productive
than barley, as food for poultry, who are very fond
of sunflower seeds, and eat them greedily. This climate
is not exactly suitable for the growth of buckwheat,
the seeds of which are excellent as food for fowls, but
if it were suitable, there can be no doubt that it would
be extensively grown, and since that is impossible, we
may regard the sunflower as a good substitute. It will
do for poultry of every description, and it grows
rapidly and readily, almost anywhere; it gives no
trouble. I have grown it to a gigantie size, 9ft. or
loft. high, at all events, with exceedingly large heads,
full of hundreds and hundreds of seeds, and this too
without any trouble whatever, and without any manur-
ing or preparation of the soil.

producing an instrument which, in principle only. was similar to the present. The perfecting of the arithmometer, from its primitive form, was still to be accomplished, and it was not till after many years of practical experience that it was brought to a state of efficiency. Indeed, it is only recently that the latest improvements, or what we may call the finishing touches, have been applied, by which its manipulation is rendered as easy as child's play.

Although the inventor's first object was to supply the want of his own peculiar sphere (insurance companies), it may be readily conceded that his idea soon took a far wider flight, and suggested its employment in the various branches of commercial enterprise, in most of which the arithmometer is now employed in France, as also by bankers, philosophers, and men of science, by whom it is found to effect a great saving of time. It is coming into use in Russia and America, but there high protective, almost prohibitive, duties are a bar to its rapid development.

The instrument is a marvel of rapidity, and those who feel interested can see its manipulation at my office. Since writing the above, I have heard that M, Thomas de Colmar died on the 1st of March last, in the 85th year of his age, acting until then as director L. DE FONTAINE MOREAU, 4, South-st., Finsbury.

of the Sun Fire Office.

INDEX FOR DIVIDING PLATE.
SIR,-Allow me to suggest a trifling alteration in the
usual arrangement of lathes for ornamental turning,
which, however, I do not in any way claim as an idea
of my own or a novelty. It is that the index, or
spring point for the dividing plate, instead of being
placed, as it generally is, on the near side of the man-
drel (that close to the operator), should be fixed on the
side farthest from him; mine has been in the position
I propose, for many years, and though at first it seemed
a little awkward having to stretch the hands across
the mandrel for every change of division, I got used to
it almost immediately, and soon found the convenience
of the new arrangement. The advantages are, instead
of the head of the index coming between the eye of
the operator and the hole into which the point is to
drop, as it does in the ordinary plan, you look, as it
were, under the spring, and have the division always
in sight; the light falls much better on the divisions,
and, if necessary, it is easy to throw additional light on
them by placing a piece of white paper in such a
position as to reflect light on the dividing plate, which
cannot well be done on the near side.

Though I almost invariably use
the index as I have described it,
I still retain one in the ordi-
nary position, so that, in case of
requiring unusual steadiness in
the work for some special pur-
pose, I can use both the indices at
once, in opposite sides of the
The upper end of
mandrel.
each index is carried round into
a curve, and bent back so as
to form a convenient handle to
take hold of, as in the accompanying figure.

STAINED GLASS.

G. C. C.

SIR, In answer to Gustavus Knox's question 2233, No. 261, I have been doing all I can to give him the information he desires. The following is the result of my inquiries:-There is only one stala used for glass in England, that is yellow. There are many There are tall and dwarf varieties of the plant, but different shades, but they have all one base-namely, silver. The flux for silver is antimony; the silver is the above-mentioned size, equalling in fact the Heli- melted in a crucible, when melted, it looks like a black anthus Californicus, I can only attribute to some peculiarity in the soil or in the air. If there be sun-deposit, and is put into clean water from the crucible, shine, it will certainly grow vigorously in damp lands, then it is ground as fine as the finest flour; when required and it takes up a great deal of moisture, and if planted for staining, small portions are mixed with Venetian on an extensive scale there can be no doubt that it red, or common red ochre, which forms a vehicle for the silver. The ochre and silver are ground to the would contribute to the health of a place by assisting consistency of very fine flour, and by adding a little in the destruction of the various miasmata which have such deadly and potent effect on human beings. A gum water, are made to follow the brush just like paint. saline atmosphere is no obstacle to its growth; on the It is laid or flowed on the glass according to the design contrary, it grows well when sown near the sea. required, rather thick; it is then allowed to dry, then There is a considerable quantity of pith in the stalks, placed in the burning oven; when it has been subwhich I should think might be used to some profitable jected to a gradual moderate heat for about four hours, account, and the stalks themselves, if broken up and the grating of the oven is pulled out, and when cold, well dried, form an excellent sort of firewood. The the silver has eaten in the glass, produced a bright seed is not perishable, and with proper precautions yellow stain, while the ochre washes off with the greatest ease. If a deep yellow is wanted, the promay be kept a very long time in good condition. The stalks, when burned, yield potash. In many portion of silver is increased, and just as the yellow instances, several heads will appear on one plant, but it is to be light or dark, so is the amount of silver regulated. "The reddish brown" stain is produced by is advisable to destroy all of them while young, except the largest, which will then increase in growth, and using brown enamel; the blue, by using blue enamel, and the different shades of all colours, except yellow, furnish an abundance of rich seed. are produced by using enamel. The enamel is ground very fine, just like paint; a large slab of glass or iron is used. The ground enamel is placed upon it, THE ARITHMOMETER. and a large glass crusher is rubbed upon it by hand SIR.-Our old friend, the arithmometer, or calcu- until it can be worked just as paint is worked. The lating machine (by which all the rules of arithmetic flux (glass and red dead) is also done the same as the are worked, and calculations of the greatest intricacy, enamel; both are worked to form a substance of the both for financial and scientific purposes, performed consistency of paint, and, when painted on the glass, as with unerring accuracy and promptitude), is gaining required, the flux leaves the enamel to melt in the window-glass, and produces the beautiful colours favour in England, as evidenced by its employment referred to. There is great art in the burning of the amongst the most eminent engineers and leading colours in the glass; success is only attained by long actuaries, and also in Government offices; yet its pro- practice. The glass itself is so various in its nature gress here is slow, considering its merits, compared with regard to being hard or soft that only those who with what it is in France, which, it should be borne by long practice in the business have come to underin mind, is the country of its origin. This restric-stand these things are fit to become glass stainers. tion to its usefulness is doubtless in some measure also due to the inventor not being, like many inventors, a needy man, and leaving the instrument to work its own way.

TAUTAU.

In bringing out the arithmometer, M. Thomas de Colmar proposed combining cheapness with simpli city of construction and portability, a problem which, at that time (nearly thirty years since), appeared of doubtful realisation. M. Thomas de Colmar, however, applied himself to the task with the energy of a man determined to conquer all difficulties, not the least being his ignorance of practical mechanics, and by dint of time, labour, and expense, he succeeded in

Jos. LEICESTER.

ROTARY ENGINE.

SIR, I have noticed several specimens of rotary engines in the ENGLISH MECHANIC, and if you think this worthy of your notice, I shall feel obliged to you for its insertion, as it may be of use to some of the It is called readers of the ENGLISH MECHANIC. Hammond's rotary engine. A, Fig. 1, is the outer box, which is stationary, with the end or side plate

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off, showing the interior; B the inner box, which revolves; D pipe for conveying the steam to the cylinder; G waste steam pipe; F a sliding plate through the outer box; E a spring to keep the plate close to the inner box. While revolving, the steam enters at P and makes its exit at R, whereby a rotary motion is obtained without compressing the steam again in the engine before it can make its escape, which is the case in most rotary engines. PHILIP.

SLEEP.

SIR,-In your issue of April 8, I find a scrap of information at the head of the section of your paper designated "Chips," which I should like further information upon. The passage reads as follows:-"M. Sommer propounds a new theory of sleep; his idea is that sleep is simply a result of the deoxygenation of the system, and he believes that sleepiness comes on as soon as the oxygen stored in the blood is exhausted," In the first place, I should like to know who M. Sommer is, and in what particulars his theory differs from the popular theory. The fact is, I very much desire (by your permission and through your invaluable paper) that the subject (sleep) should be thoroughly ventilated-i.e., come to some conclusion, scientifically, as to what sleep is, and what is the cause of sleep. Personally, I should be much obliged if any one of your numerous correspondents could point me to a good work on the subject. COMA.

GEOGRAPHY AND EMIGRATION. SIR,-There are two reasons why I should be very careful when writing anything for insertion in the ENGLILH MECHANIC. The first of these is, that your space is very valuable, aud, therefore, it is desirable to say what we mean in as few words as possible. Secondly, my time is limited, and upon this score fancy must never be allowed to rohm. You have kindly intimated that space is at my disposal to give epitomised accounts of the transactions of the Royal Geographical Society. It has struck me that whilst doing this I can be of much more service to your readers, and supply a vacuum in our periodical literature. Emigration is, and has been for a long time, a standard topic for conversation and debate throughout the length and breadth of the country. There are questions-and are very difficult ones to answer which arise upon the first thought of emigration. When shall I go? What country or colony am I most suited for? To answer these questions it is necessary to be acquainted with the various natural characteristics of the colonies, &c., open to emigrants, their climate, fauna, flora, &c. Now, Sir, backed up by the splendid library of the above-mentioned society, I think if your readers who wish for some instruction regarding geographical matters will kindly forward queries to you in the ordinary way, embodying in them their special requirements. I shall be enabled to give the iLformation required at an early moment.

BEES.

F.R.G.S.

from the weather is very picturesque, but is a great
evil, as it harbours earwigs and a host of enemies to
the bees; an old cracked red basin, or, in fact, any-
thing but straw, to keep the wet off is all that is needed.
Besides, these straw roofs are generally fixtures, and
then the impossibility of taking the honey without
killing the bees. All observations, and as much of
necessary work as is possible, should be carried on in
the year. With quietness and self possession, the bees
will never sting. I will add no more.

ONCE A BEEKEEPER.

THE "PHANTOM" WHEEL.

SIR,-Will you kindly allow me to ask those of your
readers who are not yet our customer to suspend
their judgment for a week, alike upon the claims
and the condemnations put forth in the modest letter
of Mr. Edmund M. T. Tydeman, which appeared
in your last issue. Pressure of business of other
kinds, and the very limited time within which I
understand you will go to press with your next
number, prevents me from now dealing with the
subjects.
J. A. MAYS, Secretary and Manager, Phantom Veloce
and Carriage Wheel Company.

EXTRACTS FROM CORRESPONDENCE.

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A GOOD SUBSTITUTE FOR BINDING SCREWS. -E. C. Murray writes as follows:-" I send the following, thinking that it may be of service to those of your subscribers who have, or are about to construct bat eries in which "carbons" are used. Bore a hole in the top of the carbon in. deep, and about fin. in diameter, scrape it out towards the bottom so that it is rather larger than the top; procure a piece of stoat copper wire about 8in. long, bend the end, thus, make the end of carbon hot in a clear fire

take itont, place the crooked end of the wire in it and fill it in round the wire with some solder (which should be melted in a small ladle). Of course the other wire may be soldered to the zinc. To connect the batteries. I clean and lap the ends over in, and bind them with some fine copper wire, which must be clean.

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THE ENGLISH" VELOCIPEDE.-"Over Sixty says: Living in a country where there are many hills to mount, I am always looking out for a three-wheeler that will really go up hill. I want one for use, and not for mere amusement. It strikes me that the arguments of A Thinker' in favour of the front guiding wheels bearing the load are good, but the principle of his machine seems to me to be précisely similar to the Edinburgh' velocipede, manufactured by Mr. Brown, 57, St. Leonard'sstreet, Edinburgh, the latter having a much lighter appearance on paper than A Thinker's. The Edinburgh' weighs from 54lb. to 60lb., but in the drawing of the Edinburgh,' although evident that the guiding apparatus is on each side, it is not made plain what the contrivance is. The driving wheel behind is higher than the two front guiding wheels."

REPLIES TO QUERIES.

[1875.]-ANGLE IRON HOOPS.-"N. B." can find the length of angle iron for the hoops, by adding six times the greatest thickness of the iron to the circumference of the hoop, which can be found by using the rule given by "Leo I.," p. 510, Vol. X., and for the length of the iron for the hoops, with the flange on the inside, subtract six times greatest thickness from the circumference of the outside diameter. In the two

hoops that he gives, first one, 2ft. diam. inside, with flange on the outside, circumference 2ft. = 75 3in., add 6in., which is about six times the greatest thickness, and it gives 81:39in. 6ft. 9 in. for the length: the subtract 6in. from 75-3in. =69-39in. = 5ft. 9 in. This other one, 2ft. diam. outside, with flange on the inside, rule was given to me by a foreman boiler maker.

SCIRE VOLO.

[2000]-PROBLEM.-In the first number of the present volume, there are solutions to my query, and the result in each case is, that "the difference between P and Q is equal to half the difference between the weights of the arms," which is not the solution asked for in the query. As the answerers of the problem doubted the correct copying of it, I wrote to or three from "Todhunter's Mechanics for Beginners," chap. weeks ago, informing them of its being correctly taken XII., sum 12. As my answer did not appear in your paper, I presume it was overlooked, and I again beg to thank "Franck" and others, who solved the problem, The author of The Cook's Oracle" had, for his and should be glad to know whether the sum or the time, one of the finest collections of instruments in answer is worded incorrectly in "Todhunter's" book. England. No expense was spared by him in the pur-Y. P. W. chasing, and no one knew better how to preserve the objectives from injury.

DR. KITCHENER'S TELESCOPES.
SIR,-I am glad that an inquiry for Dr. Kitchener's
telescopes has been made. I hope that some of our
many readers who are interested in astronomy will be
able to answer the question.

I am therefore inclined to think that wherever they
now are there must be some of those fine treble object-
glasses made by Peter Dollond a hundred years ago.
I have heard the work done then was superior to
much for some time afterwards, though, I have no
doubt, inferior to the productions of our best artists of
the present day

Still, a great interest attaches to these telescopes.
It is well known that some fifty years ago Sir John
Herschel published his formula in the "Philosophical
Transactions." And he says in 1861 that they still are
generally the tables used by our best opticians. But
when Dollond made these triple object-glasses, no
tables practically of any value were in existence. I
suppose he found out the curvatures by successive
trials.

Mr. Webb need not be afraid that we shall be weary of his "Hints." Anything from the author of that delightful book, "Celestial Objects for Common Telescopes "-a book which has made more astronomers than any other in the English language-will always be received with pleasure.

Will any of your readers kindly state the smallest aperture with which they can see the comes to Rigel? I have found 2in. show it well when the night has been by no means good.

I entirely concur with "F.R.A.S." in thinking that 4in. is the very smallest object-glass which will pick up six stars in the trapezium.

I am glad the name of Mr. Wray has been lately brought forward. I have seen some fine work done by him, and his prices are extremely moderate-which just now is a great recommendation.

STELLA.

SIR, As I see a proposal to have space in the ENGLISH MECHANIC for amateur farming, I would, in the event of such space being given, say a word on profitable bee-keeping. I learnt my lesson from ths aged apiarian, Mr. Payne, of Bury St. Edmunds. He always asserted that it should be made a paying businoss; and if. on an outlay in the spring of 10s., one hive will, as is often the case, produce 161b. of honey, and PRESENT STATE OF OUR KNOWLEDGE OF more, it would go a long way towards paying the rent. METEORITES.-Herrr Rammelsberg, of Berlin, has Mr. Payne, although having all the new inventions of just given a summary of what is known, from a his day, yet adhered as a rule to the flat-topped straw mineralogical and chemical point of view, of the hive, with a hole 4in. in diameter on the top, which meteorites, those messengers from other heavenly was plugged up in the winter, but which in honey-bodies which from time to time reach our earth. The making time was taken out and a smaller hive of essential constituents which are always present in straw, or a bell glass, or an old tea-chest, placed over it. In a " cap," as it is technically called, of the latter kind, I have myself secured 161b. of honey in a few weeks. The hive itself should not be fastened on its stand by mortar; we may leave the bees to do that; they will do it effectually. A straw roof to preserve

very distinct classes of these foreign bodies are
nickel, iron, phosphorus, sulphides of the metals,
oxides, silicates, free silicic acid, and, in rare instances,
carbon, or combinations of carbon. The same subject
is treated at great length by M. Daubrée in the
Journal des Sarants for Jan., Feb., and March.

[2143.]-SOFTENING CAST IRON.-" Blue Ruin "

is in error when he states that "G. B. K" cannot soften cast iron. He can do so by heating the metal to a bright red, cooling quickly in water, reheating, and then annealing by cooling slowly in ashes.-J. B.

[2153.]-VERTICAL SAW FRAME.-I doubt very much that " J. T. W." would ever get a frame to cut his oak logs, unless he went to an enormous expense, that is if the timber is English oak, at such a place as Sunderland, for wood ship building. I never knew the English oak cut up with the frame, unless it was pretty straight along the bottom, or was first sided up on two sides.-MILL SAWYER.

[2184.]-SULPHATE

OF LEAD BATTERY.Will "A Good Boy" please say whether he amalgamated the zinc plates to his battery, and will some experienced contributor inform me if it is better without ?-PLUMB. SULPH.

[2223.]-ENGRAVING ON SLATE.-I see two correspondents giving advice on this, but I doubt the querist will be much aided by it. I have cut some thousands of letters on slate, and my mode is, draw in the letters with a blacklead pencil, if wanted very accurate, come over with a draw point, taking a square graver, cut a deep bold line up the centres of the letters; this line if done with one cut will be broken and jagged at the edges, then take a flat tool (a tool about a quarter of an inch broad, and sharpened exactly the same as a joiner's chisel, but mounted in a graver handle), and with the flat side to the slate, cut from the centre stroke to the outside edge of the letter, holding the tool so as to cut the outside of the letter bevelled; it cuts as clean as a bit of cheese, the letter when finished being deep in the centre and bevelled off to either side.-I. N. G.

Leicester among the "Letters to the Editor."-Ed. [2233.]-STAINED GLASS.-See answer by Mr.

E. M.

[2286.]-DIRTY CEILINGS.-Only ceilings, the outer portions of which are exposed to the influence of temperature, have the " ribbed " appearance. In da np weather the plaster absorbs moisture, the dust and smoke adhere to the damp portion; the joists keep the plaster dry, hence that portion is less dirty and smoke-stained.-THE WELSH SHEPHERD. [2263.]-AMBER.-Amber is soluble to a certain extent in alcohol, ether, chloroform and turpentine.BETA.

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THORPE.

[2297]-VIOLET INK-Boil 4oz. of logwood in 14 pint of water to one-half, strain, and ald 6 dr. of gum and 14oz. of alum; set aside for 12 hours, and decant for use.-BETA.

[2309.]-ETCHING ON GLASS.-- To etch on glass with fluor spar, cover the glass with beeswax by melting the wax and running it over the glass, about 1-16th of an inch thick, then write on it with a needle, after which sprinkle some fluor spar upon the writing. and pour sulphuric acid on it, let it stand for 10 or 12 hours, then wash off the superfluous acid, and take off the wax and wash the glass clean, and it will be seen that the fluor spar has eaten away the glass on those parts not protected by the wax.-PRACTICUS.

in. to the foot. A board should be cut out and boat built up to it.-MATY.

"char

of this cone must of course be inclined at 70°, then a tangent to the base of the cone passing through the [2324.]-GYMNASTICS.-Let "Gymnastikos horizontal trace of the line, will be the horizontal the ends of the posts that are let into the ground, and trace of the second plane (H T); the plan of the line of they will last a very long time indeed; another plan intersection of these two planes must pass through the is to steep them in creosete oil a week or so before putt-plane of the apex of the cone, and through the intering down.-MILL SAWYER. section of the horizontral traces of the two planes. It is easily seen that the horizontal trace of each plane is

[2341 AND 2355.]-CANOES AND BOATBUILDING. I have seen several inquiries on this subject, and had hoped that some abler pen than mine would have answered them. For the benefit of canoe builders I give below the dimensions of the Rob Roy class, as published by the club:-Length over all, 14ft., beam outside, 26in.; depth from surface of deck at fore end of well to top side of keel 11in.; keel to project lin. outside, and to have lin. camber or round in its length. The best material for wear is English oak cleaned up or white or yellow pine are used. In answer to to 5-16ths of an inch thick, but for lightness, white fir C. D. R." the keel should be of oak or American elm; the timbers or ribs of the same, or ash; American elm is the best in my opinion. The stem and sternpost are worked of oak grown to about the right curve and planks are worked first, and then the timbers are scarphed to the keel. In building, the strakes or steamed and bent in and fastened while hot. I shall be happy to furnish sketches of any parts required, or to give any information in my power on this subject or yacht building to any who may think of attempting this pretty art.-BOATBUILDER.

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[2331-PATENT DRYERS.-The mixture is considered a secret, but the following may be the material chiefly employed :- Proto sulphate offiron (greeu copperas) is put in a clean iron pan upon a clear low fire, when melting, stir about and evaporate to dryness oaly. This substance, ground in oil, acts as a dryer. Sugar of lead. ground in oil, is the best dryer for delicate tints. Litharge is the most active dryer of all, but can only be used for dark colours, as it discolours light and blue tints. All oxides are dryers, as a general rule.-THE WELSH SHEPHERD. [2332]-UNNOTICED QUERY-The traced pat-like physical theories, and is Irish in reference to perpendicular to the plan of the line of intersec

terns for embroidery are printed, when many copies of the same pattern are wanted. If a dozen or two are only required, the patterns are made by hand, as follows:-The drawing is made upon paper, lay the drawing upon an even cloth, and perforate all the lines with a fine needle, close and even. Now take finely powdered charcoal three parts, resin one part in fine powder, mix and tie it in a piece of porous calico, so that it forms a dusting bag. Lay the perforated drawing upon your material, hold down with one hand, rub the dusting bag over the drawing, the dust falls through the holes, and forms the drawing on the material, remove the paper drawing, lay blotting paper over the dust pattern, and go over it with a worm flatting iron; the heat will melt the resin and fix the drawing on the material.-THE WELSH SHEPPHERD.

(2341.]-CANOE.-From " Oversands'" query I suppose he wants a ship for cruising, if so, the dimensions given will furnish what he requires :-Length over

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8.75

all, 15ft.; greatest beam, 2ft. 2in.; depth, less keel,
Oin.; rise of deck. 3in. This boat may, with the ex-
ception of ribs, carlins, and risings, be built entirely of
pine, which should be fresh cut from the balk, as it will
then be easier to bend and less liable to split; or if
"Oversands" prefers,
the keel can be made of
oak or American elm,
and the curved stem and
stern pieces of oak, the
ribs of chestnut, steamed
or boiled till soft, to be
fixed hot, as they set
in cooling, and will not
alter in shape when
once in; keel, allowing
for scarphs about 13ft.
long, in. deep, 1fin. !
wide, to have a rabbet
worked on each side and
up the curved pieces (as
high as boat is to go),
where the rabbet flat-
tens. Fig. 1, section of
keel midships; Fig. 2,
method of scarphing
cutwater to keel: T
places for screws, which
should be brass; Fig. 3, section of stem (stern is
similar), through a 5; Fig. 4, half of main section,

[2346.]-GEOLOGICAL MANUALS.-Having re-
gard to the limited prices, there are only three
published in England-Jukes's, Houghton's, Page's,
the publishers are knowu to all booksellers. I will
works, but the ground of preterence must depend on
now pass my opinion on these; they are all good
the student. If he likes a book that has "grit" in it,
technical and directly, ad rem, and is not afraid of a
hard book, let him buy Jukes's; I like it myself,
because conceited enough to undervalue popular works
in the popular style of science. If something easier
and more diffuse would suit, why then order Page's
Advanced Text Book;" the other, Houghton's, has
peculiar features of its own; does not so much allude
to English examples; has a good deal to say about dis-
tribution of the organic life on the globe, the orders,
their first appearance, and their extinction; takes a
glance at the" plasma" of the earth's crust, and such
examples. It would not hurt a student to buy, at tion of the other two planes. Then, if we draw a line
intervals, each of the works named. I could give perpendicular to the line of intersection, and passing
advice as to an early course for a student, but to do so through the horizontal trace of the perpendicular line,
effectually I should require to know something of his we have the horizontal trace of the third plane, and a
previous education, his means, his opportunities, his line drawn through AO will be the plan of the second
locality, &c. Perhaps I may put together a few hints line of intersection. The third line is drawn from O
on the subject for the ENGLISH MECHANIC, at no
to B, then having got the horizontal traces and one of
the vertical traces, it is an easy matter to get the other
distant period; meanwhile, I advise the student to
hang on to the skirts of the nearest practical geologist two. The inclination of the third plane is got by
he can meet with. Publishers: Jukes, Black; Page, making an elevation on a ground line, perpendicular
Blackwood; Houghton, Longmans.-F. S., F.G.S.
to its horizontal trace. Draw y' perpendicular to
H T3, and project the point O perpendicularly through
[2346.]-GEOLOGY.-One of the following works, then set up the height of the point O' taken from
might suit:-"Page's Textbook," price 68., Black- the other ground line (r), then a line vt, drawn
wood; "Jukes's Geology," price 128. 6d., Black and through this point, and the intersection of the trace
Co.; Phillips's Treatise," price 78., Longmans.- with the xy' will give the inclination required, which
BETA.
is 468.-M. WHEATLEY.
[2362]-COPPER SMELTING. - In answer to
[2380.]-MERCURY BREAK FÓR COILS.—“ R. S."
"E. V. D. S." I am not aware of there being any will find a description of a mercury break in the appen-
copper smelting establishment in London.-T. Ros-dix of "Chambers's Electricity," by Dr. Ferguson. It

KELL.

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[2363.-SILVERING BRASS.-In answer to " Poor Clock Jobber" respecting silvering brasswork or clock dials, the following is the method used for many years to silver the clock rims or inside bezils:-6d. of pure silver dissolved in half a teacup of nitric acid, the solution of silver to be carefully washed to free it from the acid; afterwards to be mixed with 1d. cream of tartar; when the tartar is mixed add half a brick of common table salt, pounded fine, the whole to be well stirred together. The articles to be silvered must be dipped clean in aqua fortis, or scoured with fine sand. The part to be silvered must be rubbed with a clean cork dipped in water, then in the silver powder. The whole to be rinsed in lukewarm water, and dried in clean box sawdust, and then be varnished with copal varnish made thin with turpentine. This is an old method. The modern one is to laquer the work with colourless lacquer.-J. M., Birmingham.

consists of a vibrating spiral of copper wire. Another form is given in Du Moncel's work on the induction coil as constructed by Gaiffe, which, like the ordinary spring break, derives its motive influence from the core of iron wires. It is constructed; as follows:-A brass pillar with a slot cut in the top carries a lever of soft iron some 6in. long, one end of which terminates in a cylinder like that of the spring break; the other end has a wire depending from it tipped with platinum, which dips into a cup containing an amalgam of mercury and platinum, or mercury and silver (which is cheaper and more easily made); the iron lever is centered in the slot by means of a pin passing through it, so that it can slightly oscillate in the vertical plane; a spring bent in the form of an arc is fixed to the under part of the lever, which, by means of a rack adjustment, can be made more or less tense, so as to accelerate or diminish the rapidity of the oscillations. The pillar is of such a height that the cylinder end of the fever, when at rest, is about fin. or 3-16th in. above the

[2371.]-HEATING OF JOURNALS. — If "Rel-end of the bundle of wires in the coil. The mercury wot" were to remove the brasses from his heating journals, and replace with hard wood, and state the result in the pages of the ENGLISH MECHANIC, it might benefit others as well as himself. It is best, if possible, for the wood to be endways of the grain. I was in a very large windmill last week, where the lower end of the wind-shaft was working against wood, but in this case, the wood was strongly bound by an iron band, to prevent splitting, as the pressure was very great, and brass had been removed on account of heating; it has been at work thus for many years. The necks of all the stone spindles in the mill, four pairs, are working with wood instead of brass in a satisfactory manner.-R. N. SMITH.

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[2376.]-GEOMETRY.-The following is perhaps the easiest method of solving this rather long problem. First of all determine by its traces (H T and V T) the plane inclined 50°, assuming this plane perpendicular to the vertical plane of projection; next determine by its plan and elevation, a perpendicular line to this plane; then a plane containing this line, no matter in what position, must be perpendicular to the given plane. To determine the position of the second plane (70°), make the point O (where the line intersects the plane), the apex of a right cone, whose slant edge is inclined at 70. All tangent planes to the slant sides

cup is capable of being adjusted to any required height, so that the platinum wire just touches the amalgam; over the amalgam is poured some alcohol, which, being less conductive than air, renders the passage of the extra-current spark more difficult. The pillar and the cup are respectively connected with the coil in the same manner as the two sides of the spring break. This form of contact-breaker is chiefly applicable to the larger class of coils, especially when used with great battery power; as before stated, it renders more difficult the passage of the spark of the extra-current, which so rapidly oxidises the platinium of the spring-break; moreover, for the same reason, it elongates the spark of the secondary wire. In a coil I recently made, the spring-break, with 3 Grove's cells (5in. x 8in. of platinum immersed) gives sparks 6in. long; the mercury break, with same battery power, gives sparks 7in. The mercury break is, however, not adapted for illuminating vacuum tubes.

J. D. M.

[2381.]-FIXING IRON STANDARDS IN STONES.in stones for wire fencing, railings, &c., is composed of The composition generally used for fixing iron standards brimstone (crude sulphur) and washed dry sand in about equal parts, poured into the joint in a molten state.VIVIS SPERANDUM.

should

[2384.]-WORK ON ELECTRICITY.-I recommend S. T. P." to purchase either "Noad's How Made, and How Used," by Dyer, price 18.-F. Inductorium," price 3s. 6d., or "The induction Coil,

RUSSELL.

[2390.]-INDUCTION COIL.-Thomas J. O'Connor may safely use a battery consisting of 6 or 8 Grove's or Bunsen cells (pints), or 3 quart bichromate cells.-F. RUSSELL.

[2390.]-INDUCTION COIL.-T. J. O'Connor asks what battery power would be suitable for his coil

If his coil is well insulated, he can use a bichromate
battery, presenting a total surface of 48 square inches,
or one quart Bunsen's battery, with about 66 square
inches. Such a coil with a condenser of 25 sheets, 6 x
4, ought to give in. spark at the least.-A. E. TUCKER.
[2399.]-DIE FROM MEDAL.-The best way for
"Medal" to procure a counterpart or die from his
medal would be either to make a mould in plaster of
Paris and cast it, or else, which 3 the better way, to
reproduce it by means of the electrotype process.-F.in.

RUSSELL.

[2403-FLUXES.-In reply to "Dorset," he can obtain fluor spar from any of the mining districts of Cornwall. I get mine from Redruth, though one of the assayers. It can be had in powder from almost all drysalters and dealers in chemicals. J. J. Griffin, 22, Garrick-street, Covent-garden, London, supplies it: white argol may also be had at the same place. White argol is the commercial name for crude bitartrate of potassa; cream of tartar is the same, purified; tartaric acid is also obtained from it. It is chiefly obtained as an incrustation in wine casks.T. ROSKELL.

[2404.]-TELESCOPE QUERIES.-I am unable to answer the query addressed to me by "C. S.," page 69, for the following reasons. I do not possess an eyepiece of the power he mentions-the highest I have used is about 300; also my telescope was left behind in Manchester, and I fear that I shall not be able to send for it before the middle of June. One point is worthy of notice, the stand seemed almost perfect on quiet nights, but if not sheltered, the instrument had an unpleasant tendency to come "head to wind," so smoothly and easily did it work. This will be remedied when I get to work again, and I think it will then be the best possible form of stand for an altazimuth.ARTHUR W. BLACKLOCK, Newbridge, Aberdeen.

[2407.]-DYEING.-" Mordant" will get the fullest information about chemical dyeing in "Musprat's Chemistry," but it is a very expensive work. Napier's Handbook on Dyeing" may suit him, it is more mechanical (if I may use the expression) dyeing than chemical, but contains a multitude of recipes for dyeing cotton and silk in all colours.-VIVIS SPERAN

DUM.

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-J. P. P.

Let 2 =

+ √ 2- 2 = (√22) or (2 + 2) [2414.]-ALGEBRAIC EQUATION.-"Pater "will find the following to be a correct solution of his problem :-Let 3r the greater number, and x = the less; then (3.x x 4) = 12; or, 12 = 12; dividing by 12. 21; extracting root, r = 1; therefore, 3x3 Proof:-3-12, the required difference; (3 × 1) × (3 + 1) = 3 x 4 = 12.-W. AIREY.

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half

Put

lemon upon 1lb. of refined sugar, not broken.
3oz. of tartaric acid in 2 gallons of cold water, let it
stand 12 hours or more, put the sugar which has ab-
sorbed the essence of lemon to it, and stir up. When
bottled, add a desert spoonful of carbonate of soda 14
a quart bottle not quite filled.-MINNEHAHA.
[2481.]-GUANO INJURIOUS TO HEALTH.-
Science Gossip, September, 1866, quotes the follow-
in fact from the Gazette de Lausanne:-"A peasant
cutting wood was wounded by a splinter, and having
afterwards worked in guano, this substance entered
the wound and occasioned death by poison af ter three
days' suffering."-X. Y.

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[2492.] BENNETT'S CHUCK.-For reply see J. K.P.'s letter on another page.-ED. E. M. [2499.]-APPARENT ANOMALY.-Edward Haberglam has got fogged by mixing troy and avoirdupois weight together. Penny weights appear in the former only, which has 12oz. to the pound of 5760 grains. It is well worth bearing in mind that though the troy pound is so much smaller than the avoirdupois pound of 7 000gr., yet the troy ounce has 480gr. against the 437 that go to the avoirdupois one, for if you go to a sale and buy plate at per ounce, as a friend of mine did, and get charged by avoirdupois, you will pay about 11 per cent too much. It must also be remembered that the apothecary's drachm is 60gr., and the drachm, as I think it should always be spelt, though we do not find much distinction made in the dictionaries, is about 27 gr., and is what we talk about when we say we put 3dr. of powder into a charge for a small-bore rifle. As regards the weight of water, we commonly see put in books that a gallon is 10lb., also that in a cube-foot there are 6-232 gallons; and should conclude that a cube-foot would weigh 62:321b., whereas we are always told it is 6241b. It would reconcile matters, and be just as easy to remember, if it were called 621b., and would be nearer the mark a good deal.-J. K. P.

the appendix to the "Nautical Almanac" for 1851.-
HENRY W. HENFREY, M.N.S., &c., &c.
[2450.]-FASTENING PIN TO BROOCH. In
answer to "Yorkshire Bite," he must use shellac to
fasten the pin or joint in his brooch; this is what the
black ornament makers use in Birmingham. The joint
is warmed previously to putting together.-J. M
[2455.]-FRET CUTTING ROLLED BRASS.
Chip had better use coarse cut saws to pierce his
brass with, as the fine ones get hot, and then
merely rut, not cut; he must lubricate with a little
suet or wax, and not work his saw too quick. I have
cut some metal thick, for book mounts, and I found
fine cut saws of no use whatever. Perhaps he would
let me know how he succeeds in his next attempts ?-
J. M.
[2456.1-OLD COINS.-The first-mentioned pieces
of" Shahazadah," are merely Nuremberg tokens or
counters, and are of no value. He will find many par-
ticulars relating to them in the last volume of the
ENGLISH MECHANIC. See pages 309, 537, &c. The
following is a description of the "Voce Populi
pence. Obverse, a laureated head to the right, the
neck being bare. Legend; VOCE POPULI. Reverse,
a female seated, looking to the left, holding a branch
in the right hand; a spear. pointing backwards, is
supported by the left arm, and behind the figure is a
harp; HIBERNIA above, and the date, 1760, below;
There are a great many minor varieties, which I need
not notice here. I extract the following from the
1760, very little copper money was struck for Ireland.
Numismatic Chronicle:"-" For some years prior to
which caused such a scarcity of small change that all
sorts of base stuff was cast into pieces that passed for
halfpence and farthings. This gave an opportunity to
a Mr. Roche, of South King-street, Dublin (who struck
metal buttons for the army), to issue copper halfpence
and farthings, which were generally received in pre-
ference to the wretched sort then in circulation. The
first sort he sent out was badly finished, and on one
side a head laureate, looking to the left, and for in-
scription, VOX POPULI; reverse, Hibernia sitting
on a globe, holding a laurel branch in the right hand
and a spear in the left, with HIBERNIA round; in
the exergue the date, 1760 (none of these sort are now
known to exist). The second sort that he issued was
much neater, and better copper, with the inscription
on the head side altered to VOCE POPULI. The half-
pence were a larger size, and done in the same manner.
However, on information being given to the then Lord
Mayor of Dublin, the whole apparatus for striking the
aforesaid coin was seized and lodged in the thōlsel.
Roche fled from the same." The most comprehensive
account of these curious pieces is by C. Clay, M. D.,
published in Part III. of the Proceedings of the Man-
chester Numismatic Society," 1866. The medals in
brass of Admiral Vernon, are very common, not being
worth more than 1s. I have two specimens in my
cabinet, commemorating the taking of Porto Bello.QUERCUS.
HENRY W. HENFREY, M.N.S., &c., &c., author of a
"Guide to English Coins.'

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culty would appear to be that no contact is completed. [2501.]-INDUCTION COIL.-T. J. O'Connor's diffiHe must not expect an iron screw and steel spring to work to any sort of satisfaction. The metals would be immediately oxidised and rendered non-conducting, and no doubt this is the case now at the point of actual contact of screw and spring.-SIGMA.

NOTES AND QUERIES.

[2503.]-TOBACCO FUMES-Cau any reader inform me of the best mode of deodorising a furnished room containing tobaeco fumes ?-R. W.

[2504.]-UNIFORM TEMPERATURE.-How can I keep the temperature of a room, and a tank of water in it, at exactly 50° Fahr., both in winter and summer?

[2505.]-WEIGHT OF WATER. What is the [2456.-OLD COINS.-The one figured is a Nurem-weight of a cubic foot of fresh water and sea water, each at 60° Fahr. ?-QUERCUS. berg token. The words "Hans Krauwinkel, Nur." are very legible.-BERNARDIN.

[2456.]-OLD COINS.-Is a counter or jetton; made by Hanns Krauwingel, whose name appears on the coin. If "Shaazadah will refer to "Snelling's View of the Origin, &c., of Jettons or Counters," or even to the ENGLISH MECHANIC, a few weeks back, he will find all, or as much other information he may require. The Voce Populi," or "Pretender's halfpenny," as it is sometimes called, was struck in Ireland in 1760. [2416.]-ADHESIVE MATERIAL.-A thick mix- It is rather smaller than an ordinary sized halfture of dextrine and water possesses great adhesive-penny of the period. There are conflicting accounts of ness. Dextrine, or British gum, is made by exposing its appearance as a singular and distinct coinage, and potato starch to a temperature of 4000. It is a cheap it is singular that its origin should be lost in obscuarticle, and largely used as a substitute for gum. rity, considering its comparatively recent date. The BETA. various authorities on the subject are brought together and printed in the "Proceedings of the Manchester Numismatic Society," Part 3. There is a variety with the letter P in the front of the bust, and another with P under the bust. There is also a farthing size. The Vernon medal was probably struck on the taking of Porto Bello, and I dare say some of our medal col lectors will send information.-D. T. BATTY, Fennell

[2420.]-SPRING BOW-A steel spring bow of given length cannot be weakened except by reducing its substance in thickness, or otherwise.-J. B.

[2423.]-AQUARIUM.-Why does not your correspondent use gas piping? I have used it continuously for several years. My fishes lived and got fat, yet I never fed them, but kept the aquarium well stocked with vegetation. I have found no cement to surpass Portland cement, it hardens under water, and makes a good artificial stone.-COUNTRY GROCEB. [2423.3-AQUARIUM.-Gutta-percha does not affect water in any respect, neither fish or any other thing will be therefore injured by water which has passed along pipes of that material, Roman and Portland cement are suitable for uniting rock work, and can be obiained by any mason; but both of these, and the former especially, give off an efflorescence for a time, which is poisonous to fish if the water gets impreg

nated with it.-J. B.

[2424.]-MICROSCOPICAL. The Quekett Club publishes a quarterly journal, which is supplied to its members free of charge, and which contains reports of the proceedings of the club, and in which the most important of the papers read at the meetings are published in full, with illustrations, when required. A member unable to attend the meetings could scarcely derive any advantage beyond the perusal of the jourDal; but any subject he might wish to bring under the notice of the club, with a view to elicit opinions, or otherwise, would receive attention if brought forward through the secretary or any other member. As a regular attendant at the meetings of the club, I should be glad to be of service in this way to any absent member. Nelson's gelatine is largely used, and can be had, I believe, of almost any grocer. With Cox's I am not acquainted, nor have I ever known isinglass to be used for microscopical purposes.-W. H. G. [2489.]-SLOT CUTTING.-See "J. K. P's" letter elsewhere.-ED. E. M.

[2442.] MOUNTING LARGE CYLINDER. "Woodleigh" had better have wooden caps to fit the ends of bis cylinder, with brass bearings screw tight in the centre of the caps, and secured by a lock-nut inside and varnished with sealing wax varnish. I have one that is done the same way, and it answers well.-J. M.

[2448.)-PLANET NEPTUNE.-Adams's calculations and formula first appeared as an extract from

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[2459.]-BANKAL WOOD.-Bankal wood, of the

[2506,]-CAMPHORATED COLZA OIL.-Will C. Ward kindly state what this is, and how prepared? I have a real argand lamp, the cotton in which is raised and lowered by a rack and pinion; it gives an excellent light with sperm oil, but this is far too dear, and the common colza oil will not suit, as it crusts so rapidly, the tubes in the lamp being very close, and the cotton fine. Possibly the camphorated colza oil mentioned by Mr. C. Ward might suit.-S. J. M., Pege.

[2507.)-RECOVERING GOLD.-I see in last week's ENGLISH MECHANIC a plan to recover the silver off of plated ware without dissolving either copper, brass, or German silver, which I consider very useful. Can you or any reader of the MECHANIC give the same for recove-ing gold off plated ware, and also how to recover the gold afterwards in the metallic state, as have some old spoous that have been gilt pretty thick on the metal that they are made of, which

looks like copper ?-T. E. D.

[2508.] FASTENING STENCIL COLOURS ON PAPER.-Can any brother reader inform me of any method of fastening stencil colours on paper that will size and varnish. I have tried vinegar and alum paint, but they won't stand the size. I have used stiff to fasten the ordinary pigments that are ground for colour ground in oil and well diluted with turpentine, but it is apt to make greasy and unclean work?PAINTER.

I see that it will not do. I would like to know what

[2509.]-PUMPS.-Many thanks to "C. S." for his Philippine Islands, is the wood of Nauclea Glaberrima, private answer to my inquiry about the turbine wheel. a golden or a greenish yellow, is esteemed for its would be the most advisable plan for to send up about of the Peruvian bark order, or Rubiaceae; this wood, of tenacity and durability, is employed by shipbuilders, 4000 gallons of water in the shortest time; driving coopers, &c.; it is abundant in the Philippine Islands. power, 8ft. of a fall, and 50 gallons per minute? In For more particulars on the woods of these islands, reply to "H. B. M." There has been a ram tried see my notes in Some other trees of the Genus Nauclea yield also a good the Technologist, August, 1864. already and found to be insufficient.-PLUMBER. timber:-In Senegal, the Koos, Nauclea Africana; in I should esteem it a favour if our friend who writes [2510.]-PEPPER MOTH.-TO MR. CLIFFORD.Tahiti, the yellow wood of N. rotundifolia, hard, and us those interesting monthly chapters on curious catnata, Roxb., the Bakmee-gaha of the Singalese, light excellent for carpentry purposes; in Ceylon, N. Coadu-terpillars, or some other brother reader, would favour me with an answer. and tough, used for doors, &c. ; N. cadamba, Halamba What colour is the larva of the of the natives, and N. cordifolia, both used for building purposes; in Jaya, N. lanceolata; Angriet, Malay, brown, hard timber, very difficult for working, neveror Tjangtjaratan, light, with rather loose fine fibres, theless employed by wheelwrights; aud N. purpurea, working easily, but having no special use,-BERNAR

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pepper moth (Amphydasis betularia), and what position found in when feeding; also what it feeds on, and what localities are the most suitable to it? What time of the year does it make its appearance ?-PUPA.

inform me of a book treating on the benefit to be de-
[2511.]-BEER.-Would you or some brother reader
rived from the moderate use of intoxicating drinks as
beverages?-A. L. E.

rived from moderate drinking have been written on
[We know of no such work, though the benefits de-
and spoken on again and again. It is, however, our
opinion, grounded on a long experience and much
from the habitual use of alcoholic beverages are very
observation and inquiry, that the benefits derivable
small indeed.
point of view, but as ordinary observers of the habits
We do not say this froin a teetotal
of men. We have known hundreds of men, some of
whom were miners and sailors in Cornwall, spinners
in Manchester, agriculturists in Devonshire, and
printers in London, who have abstained for years
together from all kinds of intoxicating drinks, and
then we have known hundreds of others similarly

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