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grew in profusion on the sand banks. It struck me at the time that these rushes might he collected and made into paper. If so, it would be a beneilt to many. It would benefit Cornishmen, who are in rather low water just now on account of many mining operations being abandoned, and tt would benefit the community by introducing into the market a new material, whicn costs nothing in its cultivation, for making paper. I write this somewhat in ignorance of the quality of the fibre required In the material Tor paper. But I know that the Cornish rushes are tough, and I Bhoukl think would he just the thing.

A West Briton.


PULLEYS. - Sir,—Enclosed I beg respectfully to hand you tracing and short description of my patent wedge driving pulley. On reference to the illustrations it will be se*n tflat these pulleys are intended for transmitting power by means of wire ropes, the rope being held firmly between the sides of the palley, and thus preventing a "slip," a ilifficulty hitherto felt by colliery engineers and others whose operations rendered the use of wire rope necessary. These pulleys are extremely simple in construction, and consist of two loose discs, an iuternal wedge-ring, and a boss, or nave, divided in the centre transversely, all the castings being of an ordinary and inexpensive character. Fig. 1 ts a section, and Fig. a a side elevation. The two discs are made with an angular recess on the inner face of each, and the centre holes are cast slightly curved transversely, and made to fit with ease the octagonal bote. The Internal wedge-ring is made with a straight

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point, the periphery being concaved to receive the rope, and. In order to allow for wear upon the latter, the point is also made of less thickness than the diameter of tho rope. The nave or boss Ib provided with a flange cast on each end, which flange is for tho purpose of retaining the disc in position. The nave is faced and bolted together and bored out to fit the driving-shaft, to which it is secured by means of two short keys, driven from each end. The action of the pulley Is brought into operation by means of the pressure of the rope being thrown, on one side of the pulley, upon the internal wedgn-ring, which is thereby forced against the inclined faces of the recess in the discs on the other side of the pulley, the result being that the discs are driven apart on the bottom side and towards each other, so as to compress the rope on the top side.

The practical result of the trial of these pulleys has proved the principle to be a correct one, and, as there are not any parts to get out of order, their use must be attended with considerable economy.

W.m. Kcl&kt. 18, Gannon-street, E.C.


Sir,—Lest the commendation bestowed on this work by Mr. Dineen. p. 91, should induce some of your readers who are interested in these subjects to throw away their money by buying the book, I think it right to say that it is one of the most pretentious pieces of rubbish ever published. Its author is one of those claptrap talkers who pour out streams of high-sounding verbiage without the trace of an Idea; in fact, he is a mesmeric Barnum.

The quotation given, " it will be readily perceived by any one acquainted with electric science,'" &c, is enough proof, for the following statements no such person would endorse; but the Doctor's idea of electricity is the wildest nonsense. He talks about the gold and the chloride of lime in electricity, &c, and describes electricity as the source of matter, and containing in itself all matter, and talks generally with the umul sublime impudence of t lie charlatans who invent systems and Impose them upon others who know just as little as themselves or what they are professing to explain.

As to positive and negative, they are terms only; their value depends on the seDso we put on them. That the human body displays polar actions, like magnets, there is little doubt, and the study of tbis by Reichenbach la a valuable contribution to knowledge, very different from Doa>' assumptions, which are so gross as to destroy the ■value of what he says as to the facts and actions which he describes in common with all other writers on the subject. Finally, J. B. Dods was »o«"the discoverer of electro-biology," but simply a peripatetic lecturer thereon.



Sir,—The readers of the English Mechanic are greatly indebted Mr. Joseph Leicester for his clear description of ^lass-making and staining. I should like to see him give the poor glas*blowers who cannot afford to make new glass a hint or two how to co!onr old metal, say a pot that will hold from half a hundredweight and upwards, a cheap dark ruby from zatiniuin ore and copper, the proportion for a half hundredweight of metal. Also what amount of oxide of chromium would do for a half hundredweight to produce a good colour? Then, is there not a rich colour derived from uranium, lemon yellow? Also s cheap opal from bone ash and carbonate of barytas?

Han Ley. P.S.—I might be able to give him a few colours for glass Inreiuru.



(Continued from page. 00.)


Sir,—The needle is the accompaniment, If not the pioneer, ot civilisation. It is a rare or a make shift thin*: in savage life, and its withdrawal from use would be a sore trial to such tempers as cannot bear the accidental absence of a shirt button. We can purchase a packet of needles for one penny, and seldom think It a marvellous production, or estimate the accumulated skill that has brought this, the lightest and most extensively used tool, to its present perfection.

The majority of the mothers and daughters of England ply their needles at the rate of SO stitches per minute; many, more fortunate, make from 50!) To 2000 stitches per minute by usin at the sewing machine, while others have given up machine sewing in disgust, having selected a bad machine, or having been misled by some vendors who professed the thing could be learnt in an hour or two, and without trouble.

Let the disappointed try again, and be content to proceed slowly, but surely, acquiring first a rudimentary knowledge of the action of the needle, and the shuttle, spool, or looper employed in the formation of the stitch.

Figs. 1, 2, 3, and 4, represent a sewing machine needle


enlarged. A, the eye of tho needle; B, tho front or long groove; C, the back or Bhort groove; D, the fabric uuder the needle: E, the thread, showing the loop formed under the fabric, and the cloth plate or table F.

Most person.-, on first seeing a sewing machine needle feel surprised at the eye A being near the point, and are perplexed to understand how the thread forma its loop a thousand times per minute. Without grooves in the needle the thread would be liable to be broken on entering the fabric, but laying in the grooves B and C, protects it from cutting and fraying. If it were necessary to prevent the formation of a loop the thread would require to be drawn out faster than the needle, it being double the length of the needle through the fabric; it is this extra length which forms the loop in connection with tho pressing of the fabric against the thread and needle, preventing the thread rising with the needle. The front groove B is large euougli to allow the thread to pass up with the needle, while it is

drawn off at the back, as represented at E. Into this loop the point of a shuttle, or the hook of a lockglitch machine, enters, so that tho whole length of tutunder thread Is carried through the loop; Both aides being tightened at the same instant.

The Lock-stitch.

This application of needle and shuttle to a sewing machine was the Invention of the late Ellas 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 o, laying on sop of the fabric, and the lower or shuttle thread b, laying below the fabric, the threads being interlocked at o c c c with each other in the middle of the fabric between the four t-tltches.

It is the strongest stitch made, and cannot be ravelled. The stitch being alike on both sides, and using the least quantity of thread, it Is in treneral use, without complaint, unless badly made by an inferior machine, or an incompetent operator.

Fig. rt shows a front side, and Fig. 7 an end view of 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 one its stroke at the same instant, so that the shuttle pulls forward, and the needle upward, giving a pull of the two threads in like manner to the shoemaker when stitching the sole of a boot.

R is the shuttle reel. After winding the thread very evenly upon It by the machine, it is placed in the shuttle, and kept in a position by a spring or catch so a* to turn freely. The thrcftd iu working off it is directed from the underneath side to a hole in the bottom edge of the shuttle passing outwards, then by n hole adjoining it returns inward, then to holes in tho front end, and to tho outlet holes in the top edge of the shuttle to the fabric. A spriog in the front end of the shuttle at T, with its screw to regulate the tension or strain on the thread, gives the operator the power, in conjunction with a tension on the needle thread, to interlock the threads in the middle of the fabric; or. If preferred, to pull one thread tighter than the other. according to the requirements of the work in hand

H is a part of the ueedle bar, into which the needle is inserted and fixed by ft screw I. In the return stroke the needle descends through the fabric, the needle hole in the cloth plate, and into a slot In the metal K. against which travels the face of the shuttle. If th<-<: parts arc not truly fitted and well polished, the machine will be very troublesome, although the workmanship of other ports may be very good.

A Practical Man.


Sib,—In my letter on the subject of the SaltalreWardour-st. lathe, you have altered my sense in the -24th lino by inserting the word "cat." The cutting would be the least part of the expense of stool wheelB, as, when onco forged and turned, the cutting would be dono with no more difficulty in steel than in brass, only taking a longer time to accomplish. In the slide rest of that lathe there are several small wheels cut out of the solid steel, besides. ir I recollect right, a rack for one motion, and a segment equivalent to a portion of a large wheel for another. During the past week 1 have had to cut teeth of gin. pitch, £ln. deep, and through tract stsel {in. thick, which tool: M minutes each to do, so the cutting, alone, of ft set of wheels would not come t© verv much money, but I am not prepared to say where the necessary forgings could be got done, up to 9 or 10 inches in diameter, and soft enough to be cut at all. 'J. K. P.


Sir,—The following Information,which X copy from a contemporary, may be acceptable, supplementing as it does that given by "Minnehaha" in your last number, D. »■

"The eTeat drawback which has hitherto prevented the utilisation of this grass lias undoubtedly been the difficulty of extracting the fibre, the manual process being so expensive as almost to amouut tc*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 tho 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 la not only a slow and nasty one, but is attended with much waste of fibre; It also discolours, and, what if* most important of all, weakens the fibre. At the London Exhibition of 18i>2, 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 aboHt £45. AVhat is wanted is a cheap machine of simple construction, by which the fibre can be easily extracted; and we thluk 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 iniormatio* goes, ail the necessary requirements, has already been inverted in India by Mr. Donald Cruikshnnk, representative of the Telegraph Construction and Maintenance Company. No preparation of the leaves 14 required lor this machine; they are taken to it green, just as thsy are cut from the bushes, and in the wonderfully short space of two minutes, the fibre In tho leaves is brought out stripped of vascular matter, and in admirable condition. Tho rotting process not being necessary with this machine, the deteriorations in colour, as well as In tho strength and fineness of the fibre which follow upon the adoption of that process are avoided. A correspondent ol an ludian contemporary asserts that the samples from Mr. Cruikshnnk's machine were "fine, delicate, and even; not one was cut or broken; and the material would readily fetch ,£.~»i> 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 at so simple that it Csm be sold lor 10 rupees (-C1 sterling). We hope shortly to be able to give some further description of this machine, whicb, 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.


Sir,—If I may, I beg to Inform " St. George" (p. 54), that I believe Mr. Armltagc's method of case hardening or complete, hardening is not only uew 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 tho plau 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 plu or a piece of iron of the following dimensions :—IMn. long by 4 in diameter, and lii'W many times the retort would have to be fed with prussiate of potash before the article would be ready for cooling? R. E. T.


SIR,—In reply to "I. N. G.," anyone accustomed to turning knows that a hammer is constantly used for scttisg 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 sotting of the work. In my description of the chuck on p. 41, iMrd line, the word that being omitted before "the reason/'makes me too willing to admit that defective

ilttlnglstbe reason for my likiug my Specimen so 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 -'2nd last year (or Feburary 18th this year, with the addition of a shield for tho hands), which I have been using constantly for 12 years, and cannot suggest any improvement In. The 4-dog-chuck is the king of chucks for everything above lin. diameter, and mine the best for everything under that size. Universal chucks, with right au-l left-handed screw, and 2 dogs only, are very well for amateurs, pos-dbly, but are a delusion and a snare, and, I should thtnk, not an effective snare for a practical man. Clements made three of them, I believe, for his own use, and any one of the three fitting interchangeably oti four different lathes in his shop. I am, as I say above, not a believer in them, any more than I am En Clementa'a driver chuck, which you find put on all high-class lathes, bound, as I must be, to admit thnt Clements was a man of extraordinary talent and, perhaps, the best mechanician of his day. J- K.. P.


Sir,—I have a grave suggestion for Mr. Proctor's consideration, regarding the origin of the dark lines crossiDg the solar spectrum. They are generally supposed to be caused by the absorption of thoso 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 heme, and represent the absorption of those portions of the solar beams by the chemical action established in their passage through our own atmosphere. T. A.

ASTRONOMICAL. Sir,—1. T should be glad of an explanatlou of the reason why, in Dletrtchsen's Almanac, the time given between Che 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 Hereon el states that "the total thickness to be abraded from the edge of a spherical speculum 4Sin. in diameter, and 40ft. focus, to convert it into a paraboloid, is only 1-21333rd part of au inch.' * How is this result obtained?

Frank Fothercill.


Sir —When I think of the many uses of this plant, and of the eve at case with which it is grown, I feel surprised QMt it Is not more largely cultivated. It ought to be, if properly grown, far more productive mau uarirj, as iood for poulLry, who are very lond of sunflower weds, and eat tbem greedily. This climate Is not exactly suitable for the growth of buckwheat, tho 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 suuflower 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 largo heads, full of hundreds and hundreds of seeds, and this too without any trouble whatever, and without any manuring or preparation of the soil.

There are tall and dwarf varieties cf the plant, but the above-mentioned size, equalling in fact the Htliantkus CtUi/ornicus, I can only attribute to some peculiarity in the soil or iu the air. If there be sunshine, it will certainly grow vigorously in damp lands, and it takes up a great deal of moisture, and if planted on an extensive scale there can be no doubt thatU would contribute to the health of a place by assisting in the destruction of the various miasmata which have such deadly and potent effect on human beings. A saline atmosphere is no obstacle to its growth; on the coutrary, it grows well when sown near the sea. There is a considerable quantity of pith in the stalks, which I should thluk might be used to some profitable account, and the stalks themselves, if broken up and well dried, form an excellent urt of firewood. The seed is not perishable, and with proper precautious may be kept a very long time in good condition.

The stalks, when burned, yield potash, in many instances, several heads will appear on one plant, but it Is advisable to destroy all of them while young, except the largest, which will theu Increase iu growth, and furnish an abundance of rich seed. Tautau.


Sir.—Our old friend, the arithmometer, or calculating machine (by which all the rules of arithmetic are worked, and calculations of the greatest intricacy, both for financial and scientific purposes, performed with unerring accuracy and promptitude), is gaining favour in England, as evidenced by its employment anion get tho most eminent engineers and leading actuaries, and also in Government offices; yet its progress here is slow, considering its merits, compared with what it la in France, which, it should bo borne in mind, is the country of its origin. This restriction 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.

In bringing out the arithmometer, M. Thomas de Colmar proposed combining cheapness with simplicity 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

producing an instrument which, in principle only, was similar to the present. The perfecting at the arithmometer, from its primitive form, was still to be accomplished, and it was uot till after many >ears of practical experience that it was brought to a suite of efficiency. Indeed, it is only recently that the latent improvements, or what wc may call the finish! ug touches, have been applied, by whicb its manipulation is rendered as ea*y as child's play.

Although tho inventor's first object was to supply the want of his own peculiar sphere (insurance companies). It miLv be readily conceded that his idea soon took a far wider flight, and suggested its employment In the various branches of commercial enterprise, iu most of which the arithmometer is now employed iu 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.

Tho 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 XL Thomas de Colmar died on the 1st of March last, in the 8-jth year of his age, acting until then as director of the Sun Fire Office.

L. Db Fontainemoreau, 4, South-st., Finsbury.


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 dlvidiug plate. Instead of being: placed, as it generally Is, on the near side of the mandrel (that close to the operator), should be fixed on the side farthest from him; mine has been in the position 1 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 div'sion, 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 comiug 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, uuder 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 Ugh ton them by playing a piece of white paper in such a position as to reflect light on the dividing plate, which canuot well be done on the near side.

Though I almost invariably use the index as 1 have described it, I still retain one in the ordinaryiposition, so that, in case of requiring unusual steadiness iu the work for some special purpose, I can use both the indices at once, in opposite sides of the mandrel. The upper end of each Index is carried round into a curve, and bent buck so as to form a convenient handle to take hold of, as in the accompanying figure.

G. C. C.



Sib,—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 stain used for glass iu England, that is yellow. There are mauy different shades, but they have all one base—namely, illvar. The flux for silver is antimony ; the silver i» melted in a crucible, when melted, it looks like a black deposit, and is put into clean water from tho crucible, theu itis ground as fine as the finest flour-, when required for staining, small portions are mixed with Venetiau red, or common red ochre, which forms a vehicle for the silver. The ochre aud silver are ground to the consistency of very fine flour, and by adding a little gum water, are made to follow the brush just like paint. it is laid or flowed on the glass according to the design required, rather thick; it is theu allowed to dry. ibt-u' placed lu the burning oven; when it has been subjected to a gradual moderate heat for about four hour*, the grating of the oven is pulled out, and when cold, the silver has eaten iu the glass, produced a bright yellow stain, while the ochre washes off with the greatest ease. If a deep yellow is wonted, the proportion of silver is increased, and just as the yellow is to be light or dark, so Ib the amount of silver regulated. "The reddish brown" stain Is produced by using brown enamel; the blue, by using olue enamel,, and the different shades of all colours, except yellow, are produced by using enamel. The enamel is ground very fiue, just like paint; a large slab of glass or iron is used. Tho ground enamel is placed upon it, and a large glass crusher is rubbed upon it by hand until it can be worked just as paint is worked. The flux (glass and red 4eadj is also done the same as the enamel; both are worked to form a substance of tho consistency of paiut, and.whcn painted ou the gloss, as required, the flux leaves the enamel to melt iu the window-glass, aud produces the beautiful cotouts referred to. There is great art in the burning of tho colours in the glass; success is only attained by long practice. The glass itself is so various in Its nature with regard to being bard or soft that only those who by long practice in the business have come to understand these things are fit to become glass stainers. Jos. LEicEsTtR


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 nf aae to some of the readers of the English Mechanic. It is called Hammond's rotary engine. A, Fig. 1, is the outer box, which Is stationary, with the end or side plate

ROTARY ENGINE.—(.See preceding page.)



oil showing tie interior; B the iuncr box, which revolves; V pipe for conveying the steam to the cylinder: G waste steam pipe; F asliding plate through the outer box; En spring to keep the pinto close to the Inner box. While revolving the ateum enters at P and tnake» its exit at R, whereb* a rotary motion is obtained without compressing the steam again in the engine before It can make its escape, which Is the ease in most rotary engines. rniLiP.

SLEEP. Sir —In your issue of April S, 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. Souuncr propounds a new theory of sleep-, his idea is , Uiat sleep is simply a result of the dcoxygcnatlon of the system, and ho believes that sleepiness comes on as boon as the oxygen stored in the blood i? exhausted." lu 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 tho subject (sleep) should be thoroughly ventilated—if., come to some conclusion, scientifically, us to what sleep is, and what is the cause of sleep. Personally. I should be much obliged If any one of vonr numerous correspondents could point me to a ^ood work on the subject. Coma.

GEOGRAPHY AND EMIGRATION. Sir,—There are two reasons why I Bhould be very careful wbeu writing anythiug for Insertion in the Em.lilh Mechanic. The lint of these is, that your space is very valuable, aud, therefore, it is desirable to say what we ruean in as few words as possible. Secondly, my time is limited, aud upon this score fancy must never be allowed to roam. 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, aud has been for a long time, a standard topic for conversation and debate throughout the length aud breadth of the country. There are questions—and are very difficult ones to answer— which ariBe upon the first thought of cmigratiou. 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 tho colonies, ii:c., opea to emigrants, their climate, lauua, flora, S:c. Now, Sir, backed up by the splendid library of the above-mentioned society. I tliiuk il your readers who wish for tonic instruction regarding geographical mailers will kindly forward queries to you in 'he ordinary way, embodying in them their special requirements. J shall be enabled to give the iLforma■ it.ii required at an early moment. F.R.G.S.


Si»,—As I see a proposal to have space in the English Mechanic for amateur farming, I would, in the event of such spice being given, say a word on profitable bee-keeping. I learnt my lesson from ths aged apiarian, Mr. Payne, of Bury St. Edmunds. He ,i I ways asserted that i t should be made a paying busln#M; and if. on an outlay in the spring of 10s., one hive will, as Is often the case, produce 101b. of honey, and more, it would go a Ions; way towards paying the rent, .Mr. Payne, although having all the new inventions of his day, yet adhered a* a rule to tho Hat-topped straw hive, with a hole -liu. in diameter on the top, which was plugged up in the winter, but which in honeynuklng time was taken out and a smaller hive of straw/or a bell glass, or an old tea-chest, placed over it. In a " cap," us it is technically called, of the latter kind, I have myself secured, lolb. of honey in a lew 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

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, anything but straw, to keep the wet oil is all that is needed. Besides, these straw roofs are generally fixtures, and then the Impossibility of taking tho honey without killing the beea. All observations, and as much of necessary work as is possible, should be carried on in the yeur. With quietness and self possession, the bees will never sting. I will add no more.

Onck A Beekeeper.


Sir,—Will you kindly allow mo 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. Ertinuud M. T. Tydemau, which appeared lu your last issuo. Pressure of business of other kinds, and the very limited time within whioh 1 uidcrstand vou will go to areas with your next number, prevents me from now dealing with the subjects.

J. A. Mays. Secretary and Manager, Phantom \ cloce aud Carriage Wheel Company.


Sir,—I am glad that an inquiry for Dr. Kitchener's telescopes has been made. 1 hope that some of our many readers who are interested in astronomy will be ablo to answer tne question.

The author of "The Cook's Oracle "had. for his time, one of the finest collections of Instruments In England. No expense was spared by him In the purchasing, and no one know better how to preserve the objectives from injury.

lam therefore inclined to think that wherever they now are there must be some of those tine treble objectglasses made by l'eter Dollond a huudred years age.

1 have beard the work done then was superior to much for some time afterwards, though, I have no doubt, inferior to the productiens 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 Herscliel published his formula; in the " Philosophical Transactions." And he suys 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 tho smallest aperture with which thev can see tho come?* to ltigel? 1 hnvc found Jin. alww'lt well when tke night has been by no means good.

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

I am glad U» name of Mr. Wray has been lately brought forward. 1 have seen some fiuo work done by him. and his prices are extremely moderate—which just now is a great reeomrnendailou. Stella.

PRESENT STATE OE OUR KNOWLEDGE OF METEORITES.—Ilerrr Uanimelaburg. of Berlin, has just given a summary of what is known, from a mineralogical and chemical point of view, of the meteorites, those nie-seugTrs from other heavenly bodies which from time to time reach our earth. Tho essential constituents which are always present in very distinct classes of thpse foreigu bodies aro nickel, iron, phosphorus, sulphides of tho metals, oxides, silicates, freesiliclc acid, and, In rare instances, carbon, or combinations of carbon. The some subject is treated at great length by M. Daubree iu the Journal ties SarpnU for Jan., Feb., aud March.


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 trie* in which " carbons" are used. Bore a hole in the top of the carbon {in. deep, and about Jin . in diameter, scrape it out towards the bottom so that it i- rather larger thau the top; procure a piece of stout copper wire about Sin. long, bend the end,

thus, ) make the end of carbon hot in a clear fire

take itout, 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 tho bntterles. I clean and lap the ends over Jin. and bind them with tome fine copper wire, winch must be clean.

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 amu-cment. It strikes me that the arguments of 'A Thinker'in favour of the front guiding wheels bearing the load arc good, but the principle of his machine seems to me to bo precisely similar to the ' Edinburgh' velocipede, manufactured by Mr. Srown, 6", St. Leonard'sstreet, Edinburgh, the latter having a much lighter appearance ou paper than' A Thinker's.' Tho ' Edinburgh' weighs from 541b. to 601b., but In tho drawing of the ' Edinburgh,' although evident that the guiding apparatus is oueach side, it isnotmndealain what the contrivance is. The driving wheel behind is higher than the two front guiding wheels."


[1875.]—ANGLE IKON HOOPS.—"N. B." can find the length of angle iron for the hoops, by adding six times tho 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 flin., whioh is about six times the greatest thickness, and it gives M-30iu. = oft. <jf|ii. for the length: the other one, 2ft. diam. outside, with flange on the inside, subtract liin. from rollin. = li!) :Win. - 5ft. DJiu. This rule was given to me by a foreman boiler maker.— Scire Volo.

pooo ]—PROBLEM.—In the first number of the present volume, there are solutions to my query, ami the result In each case Is, that " tho difference between P and Q is equal to half the difference between the weights of the arms," which is not tho solution asked for iu the query. As the answerers of tho problem doubted the correct copying of it, I wrote to or three weeks ago, iuforming them of its being correctly taken from "Todhuuter's Mechanics for Beginners," chap. XII., sum 12. As my answer did not appear in your paper, I presume it was overlooked, and I again beg to thank " Frnnck " and others, who solved the problem, and should be glad to know whether the sum or the answer is worded incorrectly in " Todhunter's " book. —Y. P. W.

[2143]-S0FTENING CAST IRON.—" Bine 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 weut to an enormous expense, that is if the timber is English oak, at such a place as Sunderlaud, for wood ship building. I never knew the English oak cut up with the frame, uuless it was pretty straight along the bottom, or was first sided up ou 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 ?—Pll'mb. Sulpfi.

[2323.]—ENGRAVING ON SLATE—I sec two correspondents giving advico on this, but I doubt the querist will be much aided by it. I have out some thousands of letters on slate, and my mode is, draw in the letters with a blacklead pencil, if wanted very accurate,comeoverwltha draw point, taking asquare graver, cut a deep bold Hue up the centres of the letters; this line if done with one cut will be brokeu and jagged at the edges, then take a flat tool (a tool about a quarter of an inch broad, aud sharpeuc4 exactly the same as a joiner's chisel, but mounted in a graver handle), and with the flat side to the slate, cut from tho centre stroke to the outside edgo 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 tho centre and bevelled oil to cither side.—1, N. G.

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

[22S6.]-DIRT Y CEILINGS.—Only cellings.theoutor portions of which nre exposed to the iutlaeuce ol temperature, have the "ribbed" sppearaueo. In da'Up weather the plaster absorbs moisture, the dust and smoke adhere to this d.imp portion; the j olsts keep the plaster dry, hence that portion is less dirty and smoke-stained.—Thk Welsh Shepherd.

[2263.]—AMBER.—Amber Is soluble to a certain extent Iu alcohol, ether, chloroform and turpentine.— Beta.

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78 5 X -00546 X 60 = 25 7 cubic feet discharged per minnte—Anthony.

[KIM.]—NICOTINE. — "Maues" should put two drops of oil of sassafras on his pipe of tobacco, which will entirely prevent vertigo, and all the other disagreeable effects of smoking.—Viator.

:2i'Jl.l—THEOREM.—It seems to be a particular case of the theorem " the circle is greater than any isoperimetrical figure," which is proved in several authors.—A. Blanchet.

[2296.]—DIE.—I think "Cantab" would have a great trouole to cut a good counterpart to his die "with tools. A much bettor plan would be to stamp a copper counterpart with the steel die Itself, provided it Is hard enough. If itis not. he must harden it by one of the many recipes given in these pages. — W. II. Thorpe.

[-•297.]-YIOLET INK.-Boil4oz. of logwood in 1} pint of water to one-half, strain, and aid 0 dr. of gum audljoz. of alum; set aside for 12 hours, and decant for use.—Beta.

[230'J.]-ETCIIING ON GLASS.-To etch on glass with lluor spar, cover the glass with beeswax by melting the wax and running it over the glass, about 1-liith of an Inch thick, then write on It with a needle after which sprinkle some, lluor spar upon tho writing, and pour sulphuric acid on it, let ic stand for 10 or 12 hours, then wash off the superfluous acid, and take oft 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.—Fbactkus.

[23310-PATENT BRYERS.-The mixture is considered a seeret, but the following may be the material chiefly employed :-Proto sulphate ofjiron (green copperas) is put in a clean iron pan upon a clear low lire, 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.

[23321-UNNOTICED QUERY.-The traced patterns for embroidery are printed, when many copies of the same pattern are wanted. If a dozen or two are only required, the patterns are mad* by hand, as follows:—The drawing is made upon paper, lav the drawing upon au even cloth, and perforate all the Hues with a tine needle, close and even. Sow take finely powdered charcoal three parts, resin one part in tine 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 tho holes, and forms the drawing on the material, reniovo the paper drawing, lay blotting paper over the dust pattern, and go over it with a worm flatting iron ; the heat will melt the tesin nnd fix the drawing en the material—Tin Welsh Suepphebd.

L2341.]-can0e—From '• Oversands' " query I suppose he wants a shlpfor cruising, if so, the dimensions given will furnish what he requires :—Length over

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all, 15ft.; greatest beam, 2ft. 2in.; depth, less keel,
Oin.; rise of deck. Sin. This boat may, with the ex-
ception of ribs, carlins, and risings, bo built entirely ot
pine, which should be fresh cut from the balk, as it will
then be easier to bend and iMg liable to split; or if
"Oversands" prefers,
thekeelcan be made of r ' G *•

(uik or American elm,
rind thecurvc-d stem and
stern pieces of oak, Ihe
ribs of chestnut, steamed
or boiled till soft, to ba
fixed hot, as they set
in cooling, and will not
alter in shape when
once in ; keel, allowing
for scnrplis about 13ft.
long, ijin. deep, l*in.
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 scarpnlng
cutwater to keel: T,
places for screws, which
should be brass; Fig.
similar), through a b; Fig- 1, half of main section


3, section of stem (stern is

Jin. to the foot. A board should be cut out and boat
built up to it.—Maty.

[232I.]-GYMNASTICS.-Lot " Gymnastikos " char
the ends of the postB that are let Into the ground, and
they will last a very long time indeed; another plan
is to steep them in creoseteoil a week or so before putt-
ing down.—Mill Sawyer.

— I have seen several Inquiries on this subject, and
had hoped that some nbler pen than mine would have
answered them. For the benefit of canoo builders I
give below the dimensions of the Bob Roy class, as
published by tho club :— Length over all, Hft., beam
outside. 20in.; depth from surface of deck at fore end
of well to top side of keel llin.; keel to project I In.
outside, and to have 1 in. camber or round in its length
The best material for wear is English oak cleaned up
to 5-lGths of nu inch thick, but for lightness, white Mr
or white or yellow pine are used. In nnswer to
"C. D. U."ihekeel should bo of oakor 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
scarphed to the keel. In building, the strakes or
planks are worteed first, and then the timbers are
steamed ana 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 sub-
ject or yacht building to anv who may think of
attempting this pretty art.—Boatbcilder.

gnrd 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
now pass my opinion on these; they arc all good
works, but tlie ground of preference must depend on
the student. If he likes a book that has '• grit " in it
technical and directly, nd rem, and is not afraid of a
hard book, let hlrn buy Jukes's; 1 like it myself,
because conceited enough to undervalue popular works
in the popular style of science. If something easier
nnd more diffuse would Buit. 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
like physical theories, and is Irish in reference to
examples. It would not hurt a student to buy, at
intervals, each of the works named. I could give
advice as to an early course for a student, but to do so
tllVctually I should require to know something of his
previous education, his means, his opportunities, his
locality, Ac. Perhaps I may put together a few hints
on the subji-ct for the English Mechanic, at no
distant period; meaMwhile, I advise the student to
hang on to the skirts of the nearest practical geologist
he can meet with. Publishers: Jukes, Black; Page,
Blackwood; Houghton, Longmans.—F. S., F.G.S.

[2346.]-GEOLOGY.-Ono ol the following works
might Buit:—" Page's Textbook," price 6s„ Black-
wood; "Jukes's Geology," price 12s. 6d., Black and
Co.; "Phillips's Treatise," price 7s., Longmaus. —

r2362.]-COPPER SMELTING.-In answer to "E. V. D. 5." I am not aware of there being any copper smelting establishment in Loudon.—T. RosKf.ll.

[2363.1-SILVERING BBASS.—In answer to " Poor Clock Jobber" respecting silveriug brasswork or clock dials, the following Is the method used for many years to silver the clock rims or inside bezlls :—Od. of pure silver dissolved in half a teacup of nitric acid, the solution ot silver to be carefully washed to free It from the acid; afterwards to be mixed with Id. cream of tartar; when the tartar is mixed add half a brick of common table salt, pounded liue, the whole to bo well stirred together. The articles to be silvered must be dipped clean iu nqun fortis, or scoured with line sand. The part to be silvered must be rubbed with a clean cork dipped in water, then in the silver powder. 'Ike whole to be rinsed iu lukewarm water, and dried in clean box sawdust, and then be varnished with copal varuisli made thin with turpentine. This Is an old method. The modern one is to laquer the work with colourless lacquer.—J. M., Birmingham.

[2371.]-HEATING OF JOURNALS.— If "Relwot" 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 tho wind-shaft was working against wood, but in this case, the wood was strongly bound by an Iron band, to prevent splittirg, as the pressure was very great, and braBs 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 iu a satisfactory manner.—It. N. Smith.

[2371.]-II EATING OF JOURNALS.—" Ralwot" should apply clean soft soap, let the neck revolve in this a few moments, theu pour on common washing liquor, which will fetch out the dirt. Repeat if necessary. Thlsoan be done without stopping the engine, and has often proved effectual.—Mutual ImproveMent.

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perpendicular to tho plan of the liue of intersection of the other two planes. Then, if we draw a line perpendicular to tho line of Intersection, and pnssin" throueh the horizontal trace of the perpendicular lin<? we have the horizontal trace of the third plane, aud a' line drawn through A O will be the plan of the second line of intersection. Tho third line Is drawn from O to B, theu having got the horizontal traces and one of the venical traces, it is an easy matter to get the other two. The inclination of the third plane is got by roaking an elevation on a ground line, perpendicular to its horizontal trace. Draw ? y1 perpendicular to H T', and project the polut O perpendicularly through x';/, then set up the height of the point O' taken from the other ground line (j- y), then a line v t, drawn through this point, and the intersection of the traccwith the y j/ will give the inclination required, which isM-*.—M. Wheatley.

[2371.]-HEATED JOURNTALS.-Heated journals In many cases may be cooled by pouring a mixture of antimony and oil frequently on the in. — Yivis Sperandum.

[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 plaue (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

[2.W).]-MERCURY BREAK FOR COILS.-" R. S." will And a description of a mercury break in the appendixof "Chambers's Kleotriolty," by Dr. Fergason. It c nsi8ts of a vibrating spiral of copper wire. Another form Is given in Du Moncel's work on the induction coil as constructed by Gallfe, which, like the ordinary spring break, derives its motive influence from the core of Iron wires. *It is constructed ; u follows:—A brass pillar with a slot cut iu the top carries a lever ot soft iron some 6in. long, one end of which terminates In a cylinder like that of the spring break; the other end has a wlredependlng 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 is 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 t) accelerate or diminish tho rapidity of the oscillations. The pillar is of such a height that the cylinder end of the lever, when at rest, Is about Jin. or 3- 18th in. above the end of the bundle of wires in the coil. The mercury cup is capable of being adjusted to any required height, so that the platinum wire just touches the amalgam ; over tho amalgam is poured some alcohol, which, being less conductive than air, renders the passage of the extra-curreut spark more difficult. The pillar and the cup are respectively cennected with the coll 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 Bower; as before stated, it renders moro dithcult the passage of the spark of the extra-current, which so rapidly oxidises the platiuluin of the spring-break; moreover, for the 6ame reason, it elongates the spark of the secondary wire. In a coil 1 recently made, the spring-break, Willi S Grove's cells (oin. x Sin. of platinum immersed)gives sparks Oin. long ; the mercury break, with same battery power, gives sparks Tin. The mercury break is, however, not adapted for illuminating vacuum tubes.— J. D. M.

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


[J384.J-WORK ON ELECTRICITY—I should recommend "S. T. P." to purchase either "Noad's Inductorlum," price 3s. «d., or "The induction Coil, How Made, and How Used," by Dyer, price Is.—F. Russell.

[2390J-INDUCTION COIL.-Thomas J. O'Connor may safely use a battery oonslsting ore 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 roll 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 «fi square inches. Such a coil with a condenser of 25 sheets. 0 x i, ought to give Jin. spark at the least—A. K Tucker rj>3t».]-DIE FROM MEDAL.—The best way for ** Medal " to procure a counterpart or die from his medal would Be either to make a mould iu plaster of Paris and cast It, or else, which lit the better way, to reproduce it by means of the electrotype process .—F. Kcmell.

f24W—FLUXES.—In reply to "Dorset." he can obtain floor spar from any of the mining districts of Cornwall. I get mine from Redruth, though one of tbeassayers. It can be bad In powder from almost ail 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 nnme for crude bitartrate of potiusn; cream of tartar is the same, purified; tnrtaric acid is also obtaiued from it. It is chiefly obtained as an incrustation iu wine casks.—


[2404.]—TELESCOPE QUERIES.—I nm unable to answer the query addressed to me by "C. S.," page 6'J, for the following reasons. 1 do not possess an eyepiece of the power he mentions—the highest I hare 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 amoothly 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.

[2-407.]—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 ■ -hemlrai, but contains a multitude of recipes for <1yeingcottonand silk iu all colours.—Vivis Spexan


[3414.]-ALGEBRAIC EQUATION. —Let x = greater number ,\ x — 2 = less number, Then

x (x - 2) (2x - 2) = 12 or

x (x - 2) (x - 1) = o

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and the less number = x — 2 = 1 Or

+ J - 3 - 2 = (V - 2 - 2)or - (V ~^ 2 + 21 —J. f. P.

[2414.]—ALGEBRAIC EQUATION.-" Pater " will find the following to bo a correct solution of his problem .—Let Sr = the greater number, and r = the less; then <3x* x 4n = 12; or, 12j-> = 1.'; dividing by 12, x»= 1; extracting root, x = 1; therefore, 3.7: = 3 Proof:—,1 -1 = 2, the required differencs ; (3 x 1) x <3 + D = 3 x 4 = 12.—W. Airey.

[2410.1-ADHESIVE MATERIAL.-A thick mixture of dextrine and water possesses great adhesiveness. Dextrine, or British gum, is made by exposing potato starch to a temperature of 400°. It is a cheap article, and largely used as a substitute for gum — Beta

[24200-SPR1XG BOW.-A steel spring bow of given length cannot be weakened except by reducing its substance tn thickness, or otherwise—J. B.

B»23.]-AQUAR1UM.—Why docs not your correspondent use gas piping? I have used It continuously for several years. My lishes lived and got fat, yet I never fed them, but kept the aquarium well stocked with vegetation. I have found no cement to Burpass Portland cement, it hardens under water, and makes a good artificial stone.—Country GnocEF.

[2423. J—AQUARIUM.—Giitta-percbn does not affect water in any respect, neither fisli or any other thin" 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 lormer especially, give off an efflorescence for a time which is poisonous to iish if the water gets imnreenated with it.—J. B. h

[2424.l-MiCROSCOPICAL._The Quekett Club publi.hes 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 uuable to attend the meetings could scarcely demeany advantage beyond the perusal of the journal ; but any subject he might wish to bring under the notice of tho club, with a view to elicit opinions, or otherwise, would receive attention If brought forward »~r".?i 'he "ecretary or any other member. As a re?u ,\r attendant at the meetings of the club, I should iSJSSZ. J?,0' BerTice iu tbj8 w"y to <TMT atTM*" hLT.h i KN«Uo» » K«l«tin« is largely used, and can z.£.TMJ. 1'ev-of almost any grocer. With Cox's I am not acquainted, nor have 1 ever known isinglass to be used for microscopical purposes.—W H G

elSSS&L^gl ST1TM-866 "J- K' n" leUer

.-i!?*43iLr^,t,P^TIN'} LARGE CYLINDER.i .5!*° . had better have wooden caps to fit the ends of bis cylinder, with brass bearings screw tight in trie centre of the caps, and secured by a lack-nut Inside and varnished with sealing wax varnish I Have one that is done the same way, aud it answers well.—J. M.

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

the appendix to the " Nautical Almanac " for 1851.— Henry W. Henfrey, M.N.8., Ac, Ac.

[24.->0.)-FASTKNlNU PIN TO BROOCH. — In answer to "Yorkshire Bite," he must use shellac to fasten the pin or jolut in his brooch; this is what the black ornament makers use in Birmingham. Tbs joint is warmed previously to putting together.—J. M

r2455.]-FREr CUTTING ROLLED BRASS.— "Chip" had better use coarso cut saws to pierce his Jin. brass with, aa the fine ones get hot, and then merely rut, not cut; ho must lubricate with a little suet or wax, and not work his saw too qnick. I hare cut some metal 4 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.

[2450.1-OLD COINS.-The first-mentioned piocos of " Sbahazadab." are merely Nuremberg tokens or counters, and are of no value. He will find many particulars relating to them in the last volume of tho English Mechanic, see pages 309, 537, Ac. The following is a description of the " Vboo Popull " halfpence. Obverse, a laareated head to the right, the neck being bare. Legend; VOCE POPULI. Reverse, a female seated, looking to the left, holding a brunch in the right hand; a spear, pointing backwards, is supported bv the left arm, and behind the figure is a harp'; HI HERN'IA above, aud the date, 1760, below. There are a great many minor varieties, which 1 need not notice here. I extract the following from the "Numismatic Chronicle :"—" For some years prior to 17B0, very little cepper money was struck for Ireland, which caused such a scarcity of small ohango that all aorta 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 preference to tne 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 inscription, VOX POPULI; reverse, Hibernia sitting on a globe, holding a laurel branch In the right band 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. Tbo halfpence 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 ana lodged tn the tholsel. Roche fled from the same." Tho most comprehensive account of these curious pieces is by C. Clay, M.D., published in Part III. of the" Proceedlngsof the Manchester Numismatic Society," 1866. The medals in brass of Admiral Vernon, are very common, not being worth more than Is. I havo two specimens in my cabinet, commemorating the takiug of Porto Bello — Henry W. Henfrky, M.N.S., Ac, Ac, author of .a "Guide to English Coins."

[2456.]— OLD COINS.—The one figured is a Nuremberg token. The words " llaus Krauwlnkel, Nur."are very legible— Bernardin.

[3456.]—OLD COINS—Is a counter or jetton; made by Hanns Krauwinxel, whose name appears on the coin. If " bhaazadah ' will refer to " Snelltng's View of the Origin, Sec, of Jettons or Counters," or even to the English Mechanic, a few weeks back, he will fiudall. or as much other information he may require. The " Voce Popull." or "Pretender's halfpenny." as ir is sometimes called, was struck iu Irelaud iu 1760. It is rather smaller than an ordinary sized balfpenuy of the period. There are conflicting accounts of its appearance as a singular and distinct coinage, and it is singular that its origin Bhould be lost in obscurity, considering its comparatively recent date. The various authorities ou 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, aud another with P uudor 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 collectors will send information.—D. T. Batty, Fennellstrcet, Manchester.

[2457.]-TEA CHESTS. -I would state that it is my opinion that the chests which come from China and Assam are made from the wood commonly called here Indian teak. The country round Assam, south of China, abounds in forests of this tree.—W. StephenSon.

[3«9]-BANKAL WOOD.-Bankal wood, of the Philippine Islands, is theiwood of Nauclea Glaberrima, of the Peruvian bark order, or Jlnbiacea ; this wood, of a golden or a greeniBh yellow, is esteemed for Its tenacity and durability, is employed by shipbuilders, coopers, Ac.; it is abundant iu the Philippine Islands. For more particulars on the woods of these islands, see my notes in the Technologist, August, 1864. Some other trees of the Genus Nauclea yield also a good timber:—In Senegal, the Koos, Nnuclea Africana; In Tahiti, the yellow wood of N. rotundrfolia, hard, and excellent for carpentry purposes; in Ceylon, A. Coadunata, Boxb.. tho Bakmee-gahaof tho Cingalese, light aud tough, used for doors, Ac.; N. cadamba, Halamba of the natives, and A", cordi/olia, both used for building purposes; In Java, A', lanceolata; Angriet, Malay, brown, hard timber, very difficult for working, nevertheless employed by wheelwrights ; aud N. purpurea, or Tjangtjaratan, light, with rather loose fine fibres, working easily, but having no special use,—BeritarDin.

[2461.]-INHALATION OF IRON DUST.-Perhaps " A Turner "had better suspend a horshoe magnet over his lathe. The magnet attracts the small particles of steel that fly off, and prevent much mlschier to the workman.—J. M.

[2104]-TAR\ISHED SILVER LEAF.-Perhaps you " clear sized" your Bllver before you covered It with "mastic varnish," in which case it must tarnish. Silver again with fresh silver leaf, and varnish directly with best pale copal or body varnish. Mastic varnish is a spirit of turpentine varnish, aud does sometimes become dead and opaque—The Welsh Shepherd.

[2471.J-SUMMER BEVERAGE.—The following is a good recipe for lemonade: Pour J.oz. of essence of

lemon upon Ijlb. of refined sugar, not broken. Put 3oz. of tartaric acid in 2 gallons of cold water, lee u stand 12 hours or mire, put the sugar which has absorbed the essence of lemon to It, and stir up. When bottled, add a desert spoonful of carbonate of soda iu a quart bottle not quite filled.—Minnehaha.

[24S1.]-GUAN0 INJURIOUS TO HEALTDSciencc Gossip, September, 1866, quotes the following fact from tho Gazette dc 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.

[21«2.] - BENNETT'S CHUCK.-For reoly sec "J. K.M'.'s " letter on another page.—Ed. E. M.-

[54y9.]-APPARENTAN0MALY.-EdwardHabergham has got fogged by mixing troy and avoirdupois weight together. Pennyweights appear in the former only, which has 12oz. to the pound of 5760 grains. It is well worth bearing in mind that thou<*h the troy pound is so much smaller than the avoirdupois pound uf 7 uougr., yet the troy ounce has 480gr. against the 4.17$ thai go to the avoirdupois one, for If you go to a sale and buy plate at per ounce, aa 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 aOgr., ond the drachm, as I think it should always be spelt, though wo do not find much distinction made In the dictionaries, is about 27jgr., and Is what we talk about when wo 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 101b., also that In a cube-foot there are 6 232 gallons; and should conclude that a cube-foot would weigh 62:i2lb., whereas we are always told it is 624.1b. It would reconcile matters, and be Just as easy to remember, if it were called 62jlb., and would be nearer the mark a good deal.—J. K. P.

[2501.J-INDUCTION OOIL.-T. J. O'Connor's difficulty would appear to be that uo oontact is completed. Ho must not expect an Iron screw and steel spring to work to any sort of satisfaction. The metals would be immediately oxidlscd|and rendered non-conducting, and no doubt tbis is the case now at the point of actual contact of screw and spring.—Sigma.


ri*13.1-TOBACCO FUMES-Cau any reader inform mo of the best mode of deodorising a furnished room containing tobacco fumes ?—B. W.

[2504]-UNIFORM TEMPERATURE.—How can I keep the temperature of a room, and a tank of water in it, at exactly SU" r'nhr., both iu winter and summer .' —Quercus.

[2505.]-WEIGHT OF WATER.-What is the weight of a cubic foot of fresh water and sea water, each at 60° Fahr. ?—Quercus.

[250fl,]-CAMPHOKATED COLZA OIL.-Will C. '.Vard kindly state what this is, aud 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 tho camphorated colza oil mentioned by Mr. C. Ward might suit.—S. J. M., Pejge.

[2507] -RECOVERING GOLD.-I see in lost week's English Mxciianic a plan to recover the silver off of plated ware without dissolving either copper, brass, or German silver, '*hicb I consider very useful. Can you or any reader of the Mechanic give the same for recove-ing gold off plated ware, nnd also how to recover the gold afterwards in tho metallic state, as I have some old spoons that have been gilt pretty thick on the metal that 'hey are made of, which looks like copper ?—T. R. D.

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

[2301).]—PUMPS—Many thanks to " C. S." for his

Frivate answer to my inquiry about the turbioe wheel, see that it will not do. I would like to know what would be the most advisable plan for to send up about 4000 gallons of water in the shortest time ; driving power, 8ft. of a fall, and 50 gallons per minute? In reply to "II. B. M." There has been a ram tried already and found to be insufficient.—Plumber.

[2510.1-PEPPER MOTH—TO MR. CLIFFORD.— I should esteem It a favour if our friend who writes us those iuterestiDg monthly chapters on ourious catlerpillars, or some other brother reader, would favour me with an answer. What colour is the larva of the pepper moth (Amphijdasia betularia), an d what position found In when feeding; also what it feeds on, nnd what localities are;tlie most suitable to it? What lime of the year does It make its appearance ?—Pupa.

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

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

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