shining, whether he has north or south declination, he E sun will be vertical to them every six months, and his meridian altitude will never be lower than 66-that is, it will be rather higher in altitude than the meridian sun of June in Our latitude. Those who live in a parallel sphere, as at the poles, (Fig. 2), will lose sight of the stars for six months, not because they go below their horizon, but because the rays of the will prevent them from appearing, and H when they do appear they will go round them in parallel circles, the pole star being in their zenith, and even then they will sun E FIG E This is a question which anyone 'possessed of the aerostation than the combination of great initial velopowers of subtraction and comparison can settle for city with an aero inclined plane, an idea evidently himself. Of course, the method may have been since derived from thefact of a common kite being sustained greatly improved. It may be that these experimental in the air, when held by the line, in such a manner as results do not represent the average error, but there to float in an inclined position. It was also suggested, are no other published results on which we could form that by fixing an aero plane of oiled silk in an inclined an opinion. This, therefore, was not a hasty asser-position to a velocipede, a step forward in the right tion, made in the heat of argument, as "W. R." would direction might be made. However that suggestion imply, but simply an arithmetical fact, as he may con- may turn out in regard to actual flying, it is a good vince himself by examining the paper in which the one for velocipedes, which if moving with sufficient assertion is made in the Journal of the Chemical Society for velocity with the inclined plane attached, would tend 1868, p. 152, and following. Moreover, this expression to rise from the ground, and thus lessen the friction was the result of a critical examination of Frankland's and fatigue of the driver. In this case the action is method, forced upon us by the extraordinary argument somewhat the reverse of the kite, for the carriage proemployed by Dr. Frankland-viz., that as his process duces the wind, while at the same time it holds the and our process, when applied to the same water of inclined plane in the proper position, just as the bellyunknown composition, yield different results, ours is band holds the kite against the natural wind. necessarily wrong, and his right. mentioned. Now a bird flying against a moderate breeze does not move at a much less rate than twenty miles an hour, as may be observed from a train going at that speed. But the velocipede, as now generally constructed, cannot be driven at anything like that rate, for at ten miles an hour only the legs of the driver must make about ninety double strokes per minute, even to attain that speed, an evident impossibility. The "velocifere," however, offers a solution of the difficulty, for it can easily be driven at the rate of twenty or thirty miles an hour, and the oiled silk inclined plane attached, would tend to relieve the driver in some measure from the resistance of the atmosphere, very great at high velocity, by taking off a considerable portion of the weight of the carriage. The suggestion of propellers to act on the air, I believe to be impracticable. HENRY W. REVELEY, Reading. ACCUMULATING AND UTILISING POWER. There are other points in dispute between Messrs. Frankland and Armstrong and ourselves:-First, are nitrates completely decomposed by the treatment recommended by Messrs. Frankland and Armstrong ? We assert that they are not, and they, on the contrary, assert that they are. Second, is ammonia completely retained by sulphureous acid when its aqueous solution is evaporated with that acid? We assert that it is not so retained, and they imply that it is. Lastly, they operate on the residue obtained after the water has been all evaporated away. We maintain that no method of estimating organic matter in water is valid which necessitates this condition, as the organic matter is liable to be greatly changed, and even in some cases totally to disappear during the evaporation. On these points we have collected many experimental data, all of the simplest kind. Any one, even though he be not much of a chemist, can repeat our experiments; and without in any way wishing to pronounce a decision in the matter myself, I think I may request any of your readers who are prepared to go through the labour of making a water analysis by the method of SIR,-In the vast and rapidly progressing countries Messrs. Frankland and Armstrong to devote a few bordering on the River Plate, English settlers find one hours to the study of the paper mentioned above, and great drawback in the scarcity, often absolute want, of to a verification, by experiment, of the results fuel, the cost at any considerable distance from the ports being from £10 to £15 per ton for coal, hence A word or two in conclusion on the actual measure-requisite supply of firewood) cannot be employed as steam (until the plantations now growing, can give the ment of organic matter contained in water. kind of organic matter only existed in water, it would doubtless be desirable to measure it, and would be a very easy thing to do; but the organic matter which exists in water consists of a multitude of different E bodies mixed in proportions which vary probably with every source of water supply. Therefore, the actual measurement of organic matter is without interest. But, on the contrary, we hardly know of a virulent organic poison which does not contain nitrogen; and we do not know of a single germ, or egg, or living creature of any kind, which does not contain nitrogen. Therefore, the amount of the nitrogen forms a kind of limiting value beyond which the defilement of the water does not extend. It may not extend so far, but at this present time we are without any means of distinguishing between one variety of nitrogenous organic matter and another. As our method of analysis deals with the nitrogenous organic matter only, and brings out its nitrogen in the form of ammonia, we have called it the "ammonia" method, and not the permanganate, or alkaline permanganate method, as some of your correspondents have done. These latter terms are apt to lead to its being confounded with an older and now exploded method. FIG. 2 FIG. 3 H only behold half of the stars in the vast concavities of space, but as a compensation for this, they will be blessed with the sun's rays for six months, he appearing to describe a spiral circle round them. All the other inhabitants of the globe live in what is called an oblique sphere, (Fig. 3), the obliquity increasing more and more as we approach the poles. In an oblique sphere in our hemisphere, the polar star is always at such an altitude above the horizon as is equal to the latitude, and the consequence of living in an oblique sphere is, that the length of day and night constantly varies, the least to those nearest the equator, and the greatest to these nearest the poles. Nearly all the inhabitants therefore of the torrid zone will have an opportunity of seeing most of the stars in the course of the year the noted constellation, the Southern Cross, being visible to all of them. By elevating the pole to the latitude of any place, this will be readily apparent. Thus, London will never see stars beyond 384 S. latitude, that is, a few degrees below Formelhaut in the Southern Fish, whereas in Australia, the Great Bear will be below the horizon, and invisible. Thus the whole of the globe is visited with an equal share of the sun's rays in the course of the year, and there is nothing bid from the heat thereof the long days of summer, making up for our loss of him during the winter. F. S. H. P.S. For eclipse read ellipse, in letter 3, p. 278. WATER ANALYSIS. SIR,-My attention has recently been drawn to a series of letters in the ENGLISH MECHANIC, on Water Analysis, signed "George E. Davis," 33 66 W.R.," and Urban," "W. R." is anxious for an impartial opinion as to the relative merits of Frankland and Armstrong's method of water analysis, and Wanklyn, Chapman, and Smith's method. As you will perceive by the signature to this letter, I cannot be supposed to give an impartial opinion. I will, however, place before you the points at issue between Messrs. Frankland and Armstrong and ourselves, I must premise that the modification of Dr. Frankland's process, described by Mr. Davis in your pages, will not yield any reliable result unless a multitude of precautions, not hinted at in the letter, be taken. The volume of gas to be measured is so exceedingly small, that if these precautions be omitted, we are certain to obtain as much stray gas as will absolutely vitiate the result. My remarks apply therefore only to the process as described by its authors. "W. R.," quoting from memory, says that I stated that the experimental errors of Frankland's method exceeded the quantities to be estimated. This state ment was made by my colleagues and myself, and under considerable restrictions-viz., that the errors on the published experimental results of Frankland and Armstrong exceeded the quantities to be estimated. If one ERNEST T. CHAPMAN, 3, Redland-terrace, TEMPERING SMALL DRILLS. SIR,-There have been several queries and answers motive power. From the level character of the Pampas, water power cannot be got, consequently our only available resources are wind and the countless thousands of bullocks and horses which cover the country. Can any of your ingenious readers suggest a method by which the power of a windmill or horseroundabout, working, say three days, could be accumulated or stored up in a machine, capable of giving the fourth day, for working a set of Fowler's ploughout the whole of the power thus accumulated during ing tackle, pumping water for irrigation, or any other operation requiring more and steadier power than can be got out of the fluctuating action of a windmill, or the equally unsatisfactory work of a horseroundabout, it being in practice impossible to drive the animals so as to obtain anything approaching what their combined power ought to be. I enclose my address. RIVER PLATER. POTATO GROWING. plan of growing potatoes, I am induced to ask for a BANTING. MICROSCOPIC CONDENSER, &c. SIR,-Your correspondent "X. Y. Z." (page 305) seems to be using a very deep Kellner eyepiece as an achromatic condenser. I presume he has removed the cap which covers the eye lens of the eyepiece (that lens being used uppermost). If, when this has been of the substage, I should recommend him to exchange done, the eyepiece still interferes with the movement the Kellner eyepiece for one of somewhat less power and longer focus. An ordinary objective will make a convenient condenser if used with the lower lens next the stage. The objective may be the next lower power THE THAMES. W. II. G. SIR,-To those of your readers who can handle an oar or a pair of sculls, I can recommend a week's picnic on the Thames, starting from Oxford and finishing about Richmond, nor is any great skill or strength necessary. I like my ease, aud being middle-aged, and having a tendency towards a corporation, prefer the steering, and from a lameness in one arm, cannot stand either hard or long-continued work, yet the above excursion is not difficult for me. It will be observed that my proposal is to come down the river. Messrs. Salter of Oxford, and probably the other boat builders, let boats for this voyage, and carry them back by road. The terms are not exorbitant. I paid £2 108. for the first week, and 10s. per week afterwards for a gig with pair oars, pair sculls, and a small lug sail, the latter being, in their light boats only of use when the wind is, as a lady friend expresses it," abaft the funnel." The boat may be left at any convenient point where there is a boat yard, or sometimes in charge of the lock-keepers, and from that time the hiring ceases. This is convenient in case of a promising spell of wet weather. The crew should consist of two, three, or four persons. In the two latter cases, one or two should be ladies (of moderate age), but a single voyager, paddling his own canoe, will find it a most enjoyable trip. I went to Oxford, and to Salter, a perfect stranger, and obtained a boat without difficulty, but it would be better to write beforehand, stating what is required. which, though not exactly of the character you ne Dr. Letheby, the great gas analyst, says (in his lecture upon gas highting) that it can, as follows:"Experiments have been made for the purpose of determining the value of the light for the benzole or naphtha consumed, and the results are that every grain of the vapour taken up by a foot of common twelve-candle gas increases its light ten per cent."* The soundness of the theory being thus established, it only remains to carry it out in a convenient and effi cient manner, and for this hundreds of contrivances have been proposed, patented, and discarded, chiefly owing to the fact that the gas in passing over the naphtha always takes up the lighter portion in vapour and thus the fluid gradually becomes less volatile, and heavy, till at last no more vapour is carried off by the gas at the ordinary temperature, and the illuminating power of the gas is lowered to its former strength, till the vessel is emptied and fresh naphtha added. But the advantages to be obtained have kept the question before the minds of the scientific world, and latterly there have been plans adopted to avoid the Now as to board and lodging. There are plenty of above-stated difficulty. The price, also, of benzole The society provides boating on the river, crick inns along the course of the river-and they are really and other products of coal tar is now so much re-ing, football, quoits, croquet, &c. They have the inns-neither hotels nor public houses. They are how-duced, that the economical carburetting of coal gas can boats, of various sizes, and such other things as E ever, often full, particularly in autumn, and on Satur- now unquestionably be done with great advantage and be wanted, according to the number joining. T days and Sundays at other seasons. When this is the success, resulting in a saving of at least 30 per cent terms of membership are-58. for gentlemen, 2 k case it is a good plan to leave the boat in charge of nett. ladies, for the whole of the five summer months. a lock-keeper, and walk off to some village a mile or In No. 263, for 8th April, page 64, there is a descrip- to September (inclusive), or 1s. per month gentleme two inland. Very primitive accommodation will thus tion and drawing of a very simple and cheap plan for 6d. ladies. During the first month about 250 j in be met with occasionally, which will give zest to the carburetting gas for use in the magic lantern, which and as a result the boats are in constant use during Voyage. It is, however, rather jolly to carry with you will be sufficient to explain the whole process, and hours fixed by the committee-ie, from half-pasts the breakfast machinery, including the means of which can be made up by anyone wishing to try the to ten in the morning, and five to half-past nine in getting hot water, either by a spirit lamp or by a fire experiment himself. Such a bottle apparatus is capa- evening. On an average, there are about 40 to 50 plates of sticks on the bank. Milk can generally be obtained ble of properly carburetting ten or fifteen feet of gas at cricket daily, about 30 to 40 croquet, and the co fresh from the cow, and the other materials may be per hour, and I have used such a rough affair for sports are proportionately well patrouised, and art laid in at any village. A railway rug will often be several years with repeatedly tested results, using the members are added to the list daily; so that up to te found convenient, particularly if you feel inclined to benzole sold at 4s. 6d. per gallon. I found the power present time about 150 daily avail themselves of in disregard the popular prejudice against sleeping at of the light increased in an astonishing manner, as privileges of the society, and there is every prospec night in the open air. given below:of its being self-supporting, and possibly leaving boats and other implements of the society a clear pro fit at the end of the season. In addition to all this is intended to arrange excursions for pleasure, Tilic, geological, and archæological inquiry, to vand places of local or historical interest. At the end of season I think the committee of management will able to congratulate themselves in having promoted a good deal of healthful and innocent recreation azi enjoyment, cultivated a large amount of social an agreeable intercourse among many who otherwis would have remained strangers, kept many away from the public-house and other places of doubtful am ment, and encouraged and fostered a taste for pursuits of a profitable and educational character. There is a map of the course of the Thames from its source, to its mouth, sold by most booksellers, which is almost a necessity to anyone unacquainted with the river. It shows the position of the locks and inns, and supplies much other useful information-price 28. or 3s. If time will allow, a sketch book, a camera, or a fishing rod may be added to the other impedimenta. R. S. CHEAP GAS. SIR," Cheap Gas" (3819 No. 269) asks how to reduce his "Gas Bill," and L. M." (page 260 Vol. XII.) tells him that nearly all the plans for carburetting coal gas have proved failures, or at least have been abandoned on account of the difficulties and the absence of the economy anticipated. Now as the question of cheap gas is a very grave and important one to us all, touching our pockets, our eyes, and our health also, I do not think your readers will wish the subject should be so quietly disposed of in the off-hand manner "L. M." appears to think it ought to be. He certainly is not well informed upon the real facts and principles involved, and it would have been better had he given his opinions, and then invited those of some of the talented chemists who have contributed such valuable articles in the pages of the ENGLISH MECHANIC. I have hitherto refrained from offering any reply, hoping that some one more able to do so would have taken up this important and pressing subject, but as a month has nearly passed, and only one correspondent has written in reply, to tell us a very simple and good plan to regulate the flow of gas to the burners, which is very useful as far as it goes, yet the original question of "Cheap Gas" remains unanswered. I have given some attention to this subject, and have no interested motive, and perhaps a few practical remarks may prove of interest to your readers, and help to ventilate the question more fully, though of course we must be prepared for objections from parties interested in the existing gas companies, whole interests lie in making large gas bills at the least possible outlay in manufacture. Hence there is a constant strife between these interested parties and their customers. On the one hand the gas is kept at the lowest possible illuminating power that the law will permit, and on the other hand bitter complaints come of long bills and high prices. I do not wish to follow this part of the subject, but only refer to it in order that we may get at the real state of the case, for really cheap gas is good gas, and the question therefore is, how are we to obtain good gas? "L. M." would wish us to believe that the attempts hitherto made to enrich poor coal gas are not found to be economical, and he tells us of two or three patents, but the real fact is that the number of patented apparstus for this object are nearer one hundred, and are probably all equally without real claims to novelty, eing all based upon two well-known facts-viz., that he illuminating power of hydrogen gas entirely detheds upon the amount of carbon present in its flame. N-The great affinity of hydrogen gas for the hydromotin vapour, such as beuzole or naptha. "that coal gas is rich in these vapours as it passes municshe retorts, but the gas companies find it expemust sextract a greater part of these condensable of link is and supply their customers with a very low the valve minating gas move whetce was also lowered in proportion, there but this I e so much to complain of, perhaps, for link will vibreasons, well known to practical chevalve spindle'e have to do with gas as it is, let us centres are in ctention to the best plan left us. which what angles the tore the illuminating element to the eccentrics shoula quantity required to give a certain travel one distancay be reduced, and the nature of opposite directions,om the dirty yellow red to clear the centre of motiomot least) less heat and less carNow let me takeiric acid fumes discharged into viz. 14in. of lap anand hence into our lungs, begives us 34in." which he destruction of all property Eut there he is wrong age great question therefore is more vibration to open 8 With common coal gas (pressure-th.) No. 2 fish 10 tail burner, consuming 3ft. of gas per hour- It is not to be expected that such results could be ob- Having thus given experimental results, I may men- gas. But there are also dangers to be guarded against, as we all know (or should kuow) that naphtha is highly inflammable, and requires to be handled and used with spirits and fluids, therefore in fitting one of these carthe same care as spirits of turpentque, and such other buretters near the meter, it must be placed so as to be filled by daylight, and a cap and padlock fixed to prevent auyone tampering with it. The fluid is not explosive, and is of such strong smell, that the least leak or escape of gas is instantly detected, which is a very important consideration. The insurance offices have of course a voice in this matter, and a proper report must be made of the fitting and nature of the apparatus, but as it will require only to be refilled twice or thrice a year in ordinary cases, and to be always done by qualified persons, there will not be any objections made after due and official inspection has been made. There are other plans for using heavy naphtha, which will require to be heated over each gas burner before it will give off vapour, but these are more adapted for the workshop, factory, or open air, în which they answer very well, but require to be refilled every fortnight or so. In these plans, all dificulty with insurance offices 18 avoided, and where a working man only rents a room or so, and requires one or two good lights, without outlay, or altering the gas fittings of the house, &c., it would be the best plan to adopt. Dr. Bowditch, of Wakefield, is the patentee of one burners in use with common gas is not reduced, when I have used carburetted gas in my house for several C. D. C. BATH FORUM RECREATIONS. *Lecture upon the Chemistry of Gas Lighting, by I If any of your readers would like further informstion as to the working of this society. I shall be pleased to give it them either direct or through the colanas of your valuable magazine. R. P. EDWARDS, Bath I SHORTHAND. there is wisdom, and I trust that "Hermit" aud 20y SIP,-In the multitude of councillors, the wise man said, other recluse anxious to obtain a knowledge of the coveted art will be led into the right path. I fully endorse "W.'s" statement respecting Pitman's pho nography, and would recommend "Hermit" to obtain "The Reporter's Guide," written by Mr. Reed, one of the best shorthand writers in the world, capable of writing 200 words a minute (if necessary) and read them afterwards; he can get it through a bookseller. (at least to me) that Pitman's is the worst system. I am sorry to say Mr. Grierson has said without proof deny it, for I learnt Odell's, or Taylor's Improved, but Pitman's is far superior to it. I am between 40 and 50 years old. I was anxious that a son of mine, desiAbout three years ago I began to teach him Odell's, rous of being a compositor, should learn shorthand. but having heard a great deal of Pitman's, I made inquiries about it, and from the recommendations I received in its favour I was deterioined to master t received a teacher's certificate. I can now follow I practised with my son for about 12 months, and then close upon the heels of an ordinary speaker, whilst my son (16 years of age) can write 130 words a minute, and perhaps more at a pinch. Another young man (19), t whom I gave lessons for 12 months, but who had a paper published here; and I have a report of his of slight knowledge of it before, is now reporter on a the re-opening, last week, of a church by the Bishop of Bath and Wells, which occupies two-and-a-ha should not be judged of by the operations of those columns of the paper (Daily News size). Phonography whose inaptitude would condemn any system, but by that of those who can and do catch and imprison the winged words as they fly. If Mr. G.'s assertion is appropriate) to follow such a system. correct, we must be foolish (I think the noun more him what other system can boast of so many admirers But may I ask as Pitman's, whose devotees are to be reckoned by thousands? What system besides publishes a "Shortpher," and a "Phonographic Student," in shorthand, hand Magazine," a "Cabinet," a weekly Phonograbeides the Bible, Prayer Book, and a host of others? rent systems and to amalgamate them; it is mere "Hermit" will find it unnecessary to purchase diffe mau's), and stick to it. bearing in mind that there is Let him get one (I recommend Pitno royal road to shorthand. The phonographic motto is, Practise and Persevere." That which is easily gained is lightly valued. Phonography can be read at any time, if carefully written; and as it has three positions for writing it (for reporting purposes it is unnecesary, except нOW and then), to insert any vowels, and then generally one is sufficient; whilst half-a-dozen words can be written without taking off the pen. waste of time. T. CRIDLAND, Williton, Taunton. SIR, In the MECHANIC for the 24th instant there is some correspondence on shorthand, in which Pit's therefore, you will permit me to say a few words on system is spoken of in disparaging terms: I hope, the other side of the question. I do so on the ground that "those only who can speak from experience ought to express an opinion on the relative values of various systems; ard I think your correspondent, and read, is sufficient answer to the charge of illegi- In conclusion, allow me to say that the daily Times employs 19 Parliamentary reporters, 16 of whom write Pitman. These, at any rate, do not find it "complex and unsatisfactory," as your correspondent MacD. did. SUTCLIFF ROBINSON. This year, ROCKSALT MINE, NORTHWICH, CHESHIRE. SIR,-Allow me to give to the readers of your very superior periodical a short account of my visit to the Northwich rocksalt mine, during Whit-week. special mine, so opened for inspection, is in the occupation of Mr. Stubbs, who every year has it illuminated by upwards of 1,000 candles at one time, so that for the three days it was illuminated this year 10,750 candles were consumed. The number of visitors, chiefly from Manchester and towns around, this was 1600, This is one of the largest salt mines in the valley of the Weaver, and will well repay a visit. Outside there is nothing to distinguish this from any other salt mine. There are the usual appliances for raising the mineral, which is generally, as here, done by two shafts, serving also for the ventilation of the mine. Down by both these shafts visitors descend in the large kibbles or buckets used for conveying the salt to the surface. These are attached to long, flat ropes wound round a windlass, and worked by a steam engine. The shafts are each about 350ft. deep. The time occupied in the descent is about two minutes. On reaching the bottom the sight is most magnificent. The effect of so many lights, in higher or lower positions on the crystalline walls or massive salt pillars which are left standing to support the roof, is similar to what one might behold in looking down upon a large city when only the thousands of gaslights are seen streaming out into the darkness. The effect is considerably heightened by the many pillars breaking the long line of wails, so that no very great distance can be seen without an interruption, such as would occur from one street crossing another. Thus the long lines of light are everywhere seen in part, now ascending, or else descending, as it the street climbed a hill or descended into a valley. During the time of inspection, not only may refreshments of all sorts be obtained, but amusements also, for a good band is in attendance, which every now and then sends forth strains of martial or dance music, to the inspiritng notes of which many feet soon begin to thread the Inazy dance. For the instruction of those ignorant of mining operetions, a few men are kept working in another part of the mine, showing how, with their drills and other implements, they bore and blast the rocksalt, tearing it from its native bed in great rugged masses. It approaches the terrific when their operation for blasting is completed and the match takes hold on the charge of powder. Reverberation follows reverberation, as if the sides and roof were collapsing, or there was a complete ruin. But the visitor is soon reassured again, for perhaps his eye falls on an illuminated V. R., or a ship, or arch over a pool of water, and the reflection therefrom, or a line of streets in candles. The capacity of the mine is such that from 5,000 to 10,000 persons might easily be contained. The floor is mostly even, except where the men are working, or have left a hollow which the little water has filled up. But mostly it is dry. It is in this respect a contrast to the world-renowned Wieliczka, which has a chapel, renning stream, fresh water lake, &c.; but on the whole,it is one of the best sights on the Weaver, if Bot in ali Cheshire. B. W. LINK MOTION, POINT MOVERS, ECCENTRICS. SIR,-When reading over my last letter in No. 273, I perceived an error in that part of it which contains my observations on Mr. Harrison's letter on the link motion. In the fourth paragraph I have said, that in the link there spoken of, 4in. is the minimum mount of vibration which the middle of the link should have when working, and to obtain that the centres of the eccentrics must be shifted round towards each other to a position lin. in advance of the diameter line upon which they stand at present." Instead of in. it should be 1in. I do not know whether it is a printer's error or my own mistake, as I kept no copy of that letter, however, it is of no great consequence, as the example then given was only meant as a sort of general illustration of the necessity there exists for motion at the middle of the link, and also of the impossibility of constructsng that apparatus so that it shall have no motion at that part. "Paul Pry" asks, “Do two prime movers ever work in connection, such as a steam engine and a waterwheel, and if so, how is the coupling arranged so that one cannot over-run the other ?" It is very common for steam engines and waterwheels to work in connection, and they do so very harmoniously, and no special coupling is necessary for connecting them, the common coupling being quite sufficient, as under proper management they have no tendency to over-run or drag each other. Ascertain the least quantity of water which will drive the unloaded water-wheel at the proper speed of the mill, also ascertain the lowest pressure of steam which will work the unloaded engine at the same speed, then all water and all steam over and above these ascertained quantities go to do useful work in driving the mill, and neither over-running nor dragging can take place till either the water or the steam falls below these quantities, neither is a governor to the water-wheel indispensable in procuring harmonious action between the two, for the steam engine governor is quite sufficient for the purpose of governing both. Thus, suppose the water in the pond is slowly rising, more with pass over the sinice into the wheel, and an increase of speed will be the consequence; but the engine governor feels that, and immediately checks it by shutting off some steam. On the contrary, if the level of the water is gradually falling, less will find its way into the wheel, and a reduction of speed will ensue, which is also felt and promptly remedied by the enine-governor admitting more steam to the cylinder. I do not inean to say that a special governor to the water-wheel would not be an improvement, though not indispensable, and no person need be at the expense of putting up one for that purpose, as the steam engine governor can, by proper appliances, be made to regulate the admission of water to the wheel "Paul Pry" also asks, "What is the practical method of setting the eccentrics upon the crank-shaft, so that they shall have the required angular advance of the cranks?" and asks me to select as an example, eccentrics adapted for the link motion?" "Paul" is not the only person, by a good many, who has asked that question in your columns, for I have repeatedly noticed similar enquiries from others for several years past, but I have never met with any replies worth reading, or giving a particle of information of the least use to any person desirous of acquiring a knowledge of that most important branch of practical mechanical engineering. It is a "big" subject to enter upon so as to treat it properly, and a great deal must be said about it to the other readers of the ENGLISH MECHANIC, I am reuder it of any practical utility to "Mr. Paul" and willing to go into it with your permission, Mr. Editor, but I caution you beforehand, that I will call for a good deal of your valuable space, and, not a little of your engraver's time for illustrations. It is one of those subjects which cannot be slurred over in a letter or two, but should be properly and inexhaustively treated, or not entered upona t all. I must further inform you, good Mr. Editor, that I will not be satisfied with very minute llustrations, but will respectfully ask you for the full breadth of the page, or at least, the breadth of two columns for my drawings, such as I see you sometimes grant to impossible projects for the impossible purpose of squaring the circle, and also to showy "pictures" of wonderful velocipedes, in which the grand secret is embodied, whereby the power required to drive them diminishes as speed increases, and going,up a hill is much less difficult than going down one, and which throw the "seven league boots" of the nursery tale entirely in the shade. However, joking apart, please say if you will make room for a few "practical papers and illustrations on setting the eccentrics and valves of steam engines." JAMES BASKERVILLE, Manager, City Foundry, Limerick. EXTRACTS FROM CORRESPONDENCE. THE LATHE.-"X. H." says :-"I am much pleased to see the interest that some of my brother readers are taking in the lathe, and I trust that some of our talented contributors will give us working drawings of a first class amateur's lathe. Several of my friends have told me how pleased they have been with S. Stevens' request, No, 4070, in Notes and Queries of last week, and with which I cordially agree. I also trust in our New York friend (page 307) will give us something to work at; I have great expectations from his commuuications." EMIGRATION.-A Canadian correspondent says: time, to know that skilled mechanical labour is far in "It may be information worth knowing at the present excess of the demand in Canada at present, and members of clever and industrious artisans cannot get em ployment at their trades hore." TO MICROSCOPISTS.-W. P. says:-" I enclose you a reply to one of the queries in the current ENGLISH MECHANIC. As a microscopist of some considerable experience, I may from time to time be able to solve some of the problems which perplex younger workers, and shall be always glad to do what I can. I am glad to see my old friend, Scientific Opinion, is about to amalgamate with you." PHRENOLOGY.—“J. T." says:- I think, Sir, the foot-notes are often intended to draw information and ideas from our correspondents, and not proofs of scepticism, as many may suppose. You, Sir, have asked our correspondent if he were blindfolded, could he tell who was a merchant, statesman, preacher, botanist, engineer, &c. ? but the difficulty being that he could not tell the temperament of each subject he might examine, therefore he could not correctly delineate their character. The temperament is made manifest to the touch as well as to the sight by the fineness and coarseness of the Lair, by the softness and hardness of the flesh, &c. But it also may be said that few men rise to eminence but those who have a good temperament and organisation combined. I have no hesitation in saying that, under the manipulation of a good phrenologist, the characters and qualifications of those men might be made manifest, supposing any do not possess a combination of powers; but each one has special qualities in his individual sphere. whereby area of the aperture of the valve; = distance from fulcrum to centre of valve 34in. P = greatest pressure of steam in the boiler = 601b. per sq. in.; L = length of weight from fulcrum; w = weight of the lever = 71b. 14oz. Here the area of valve 31416 × 1:52 = 70686 sq. in. By substituting these values in the above formula we shall obtain the weight that ought to be applied scale to obtain less pressure, I will let him know the practical at endof lever. Should "One in Need "require to graduate his rule. The above formula appears: "Baker's Steam Engine," P. 35.-A. TOLHAUSEN. [3779.]-BOILER AND SAFETY VALVES.-Our correspondent, Mr. Howell, made a slight mistake in his answer at p. 309. He therein states, first the weight of valve, spindle, and lever, and adds to it the weight of counterpoise weight. Now, I must tell Mr. Howell, that it would not be correct to add the weight of the lever to the counterpoise weight, because the counterpoise weight gives the effective pressure of the lever in a line with the centre of the valve; and, therefore, includes the weight of the lever. Let him read "Jonath's" answer to "O.G.," p. 310., No. 4019, wherein he gives a very beautiful and simple rule, and which will give him all the information he requires.-THOMAS J. O'CONNOR. [3847.]-HANDRAILING.-If "J. B." will consult Langley Bank's work he will find some useful information. I cannot say whether it is the best extant. I have had Newland's, but do not make much of it, owing to the number of lines which are necessary for the working out of rails as laid down in that work. I have seen another-Jeay's, I think, is the England. There is also old Peter Nicholson's work. It is, author. A capital small work it is. I believe it is rare in however, looked upon now as old and out of date with the times. Of course you will not find the square cat Nicholson; but he has some capital ideas. Any other information on this important subject I will gladly give.— WREATH, in (385).]-TO CLEAN SADDLES.-I feel sorry for "Equestriau's" inexpressibles if he has tried the beeswax and turpentine reepie as recommended in No. 272. Let him wash his saddle with soap and water, then sponge all over with old milk, and polish with a soft cloth. If he can apply a little neatsfoot oil where there is no wear it will be all the better; but by a constant application of the milk nothing else will be required.-BANTING. have forgotten that there is 90ft. of rope added to the weigh t [3869.]-WEIGHT OF WATER.-"Countryman" must of the water at the bottom of the well.-JOE S. [3889]-PREPARING CANVAS.-First strain tightly upon frames, then wash with a thin glue; when dry it is painted with a coat of oil colour made of white lead, red lead, linseed oil and turpentine; and afterwards with a second coat, in which the red lead is omitted, and sugar of lead with a little colouring matter substituted.-(Extract from Francis' Dictionary of Recipes.)-JOE S. [3943]-BEES.-"L. W." may safely hive his swarm in the straw hive if the comb is not more than three years old; if above that age he had better cut out the two middle combs, as the cells in those combs are most used for breeding purposes; therefore the cells are much smaller through their having so many cocoons or linings in them. Each year adds from four to six to their number. I cannot quite understand why he has a box under his straw hive. What motive has an "Oxfordshire Farmer "for sprinkling the combs with sugar, &c.-quite an unnecessary operation, both for the bees as well as their owner? Bees have a great dislike to having their wings clogged with sticky liquid. When bees swarm they always leave the hive with a full supply of honey in their honey-bags-enough for them to subsist on for three days. If "L. W." would live his in a common straw hive for convenience, and then towards evening when they are all quiet, knock them out on a board or cloth and gently place the box or hive full of comb over them, they will ascend and take possession, when they may be moved to the position they are intended to occupy. A swarm hived into a hive full of comb will be a fortnight or three weeks earlier or forwarder than one placed in an empty hive. I do not think using chloroform as a means of taking hives a good plan. Driving is a much easier method. Thinking some of our readers may benefit by it, I will describe it. Towards evening, or when the bees are in, get an empty pail and invert the hive to be driven in it. Then place above it an empty hive of the same diameter as the lower one, then tie a cloth round the place where the two hives meet, so that none can escape. Then with two stout sticks beat the bottom hive for about ten minates. The operator will hear by the buzzing sound when most of the bees have ascended. On lifting off the upper hive the bees will be found hanging in a cluster, and there will scarcely be a bee left in the lower hive. The driven bees can be added to any of his weak storks, which will derive great benefit from the addition. Should "S. W." wish to know how to unite the bees to another stock, I will tell him in my next.-RECNEPS. [3940.]-THREE WHEELED VELOCE. "T. T. M." asks for something that I am afraid Andrew Johnson does not supply. Some time ago I was in want of a three-wheeled machine to carry two, aud knowing that it would be next to impossible to turn with the two hind wheels fast, hit upon a plan which works admirably. It is altogether different in the back action to anything that has appeared in our MECHANIC these last two years; and if our Editor will allow space I mean to present in a week or two the readers of the MECHANIC with a photograph and description. I will just say for the present that the back wheels are made with a groove inside the nave, against the nave loop; aud then I have a thumb screw-pin to go through the hoops of the nave, then on the axle is rivetted a small piece of flat iron, which is made to work inside the groove of wheel. When the thumb-screw is in the axle cannot pass it, so drives the wheel round when it is required. For one rider take out the pin, and all the wheels are loose. By this method the second man has great power, and still you may cut a figure of 8 with ease, as the pin on the inside wheel falls back from its work and takes it up when going straight. If "T. T. M." is in a hurry, I will furnish him with all particulars if he will give his whereabouts in your Sixpenny Wanted Column. 1f not, he and others will find a really good and serviceable machine when it is illustrated. The men sit back to back, and the two actions are independent-the first driving, as in the ordinary bicycle, the second by 5in. crank axle.-BANTING. [4025.]-HORSE POWER.-The ordinary rules for nominal horse power may be expressed as follows:-V = mean velocity of piston, in feet per minute. D= Diameter of cylinder in inches. H = D2 3/ S 15.6 D = √156H for high pressure. V = 128 S for condensing engines. V = 128 BS [4026.]-BOILER PRESSURE.-From about 401b. per square inch, upwards.-STAEM. [4028.]-FLOORING.-The flooring of chambers in Nottinghamshire and Derbyshire were of plaster till boards became so cheap. It is prepared in the following manner for floors: The stone or gypsum, or plaster, is got in a clay hill extending from Derby to Newark on the south side of the Trent, and only a few miles from the river, and parallel to it. The stone is burnt until red-hot, and then left to cool, it is then thrashed with a flail, the same as corn, until it will pass through a in. sieve; then mix with water until quite soft, as to carry in a bucket. Laid on reed or lath, sets in 12 hours, rubbed off with a stone or trowel next day. The stone is red, yellow, green, and white; the white is ground same as flour, and boiled in open bath and used for covering over plaster images, and by plasterers for setting ceilings and cornices.-A. DOUBLEDAY. [4033.]-SLIDE REST.-In reply to "J. D. L.," who inquires of me how this is done, the wheel to be cut is bored out, turned upon the edge and placed upon a stud or spindle which is attached to the slide-rest, so that the wheel face may be horizontal, and the middle of the wheel's edge level with the lathe centres. The cutting tool is a grooved steel screw a duplicate of the tangent screw to be used with the wheel. Frequently an ordinary hole or master-trap is used. This is rotated between the lathe centres, and the wheel edge forced against it by the slide screw.-W. H. N. [4037.]-RULE FOR FINDING THE SIZES OF WHEELS.-"R. T." may proceed thns and find the diameter of his small wheel-30 x 3 = 90 x 4 = 360 quarter inches, which divided by 120+ in., the diameter. "R. T." may see at a glance that 30 is of 120, therefore the diameter of the small wheel must be the diameter of the 3.1416 x 3 large one. Then to find the pitch of the wheels 120 07854in. pitch of large wheel, and the pitch of the piuion teeth. When the pitch and No. of 07854 x 120 teeth are given to find the diameter 3:1416 the diameter. -=3in. W. PROUDLOCK. P. S.-"R. T." will find some useful information on wheel gearing in back numbers of the ENGLISH MECHANIC. [4037.)-RULE FOR FINDING SIZE OF WHEELS."R. T."-In all wheels of uniform pitch the diameters are directly proportional to the number of teeth, but the diameter understood is that of the pitch circle, and not the external circle of the wheel. "R. T." will best comprehend the nature of the pitch circie by supposing two cylinders rolling in contact with each other-say of 3in. and 9in. diameter respectively, it is clear that the smaller one would make exactly Now those three revolutions, whilst the other makes one. cylinders are simply wheels in which the teeth are infinitely small, and the lines of contact are the pitch lines of the wheels. But wheels of this class are not calculated to transmit a great amount of power, nor yet would they transmit motion with the precision necessary in the majority of cases, as in clocks. It is, therefore, necessary to form notches or teeth, which may lay hold of each other so that there may be no slipping, and those teeth are formed by increasing the diameter beyond the primary or pitch line for the points of the teeth, to correspond with which, the space must be deepened to a circle below or within the pitch line. Now the great art of wheel making mainly consists in forming and proportioning the teeth properly. Several systems with those objects in view are in use, the details of which would encroach too much on your space. A simple and good rule is to divide the pitch into 15 equal parts, of which the thickness of the tooth would be 7, the space 8, the length of the tooth 12, of which 53 parts are above the pitch line, and 6 below the pitch line. The depth of the tooth may be from 2 to 3 times the pitch; thickness of rim and arms equal thickness of tooth; thickness of eye equal to pitch. Those references to arms and eye, of course, are only applicable to wheels of a large class. Supposing "R. T.'s" wheel of 120 teeth to be 3in. diameter at pitch line, 120 3 30 75, or in. at pitch line for his pinion of 30 teeth; the pitch of those wheels would be about 078, and the diameter of both would be in1 creased by the increment 057, or about in., so that the 1 16 13 16 16 diameters would be 3-in. and -in. respectively. It is very inconvenient to express in figures the pitch of wheels less than in. or in,, and hence they are usually rated so many teeth to each inch in diameter. Thus we have our wheel patterns (invariably engine eut), of 5, 6, 7, 8, 9, 10, 12, 14, 18, teeth to each inch in diameter-a wheel of 8 per in. corresponding nearly to fin. pitch. And trust those remarks may be useful to "R. T." and others.- MATRIX. [4037.)-RULE FOR FINDING SIZES OF WHEELS."R. T." may obtain the relative sizes of wheels by the following rule:-The sum of the number of teeth in the two wheels is to the distance between their centres as the number of teeths in either wheel is to its radius.-STAEM. [4039.]-BAROMETER TUBES.-In answer to this, I think if he were to fill his tube, and should there be any large air bubbles bring them out by what the French call Lacement (that is, pass a large bubble up and down until the rest have been collected by it), then heat the mercury and whilst it is boiling seal the tube close to the end.-J. W. LISTER. [4040.]-WHEEL-GEARING.-Properly, bevel wheels are made in pairs, and if the teeth were diminished ad infinitum they become simply a pair of cones, the two apeces meeting at a point where the axis would intersect, as at A, Fig. 1, the wheels B and C being properly adapted to each other. If it were desired to adapt a larger wheel D to B with the view of changing the velocity, the former must be made of the same angle as the original, this is shown in Fig. 2, where it will be seen the apex of D would reach beyond the intersection of the two axes. Practically, in connection with wheels of small pitch, and where it is often desirable to make considerable changes conveniently, it is quite usual to have what may be called a master bevel and a considerable number of change pinions, and to show what can be done in such a case by a careful manipulation, I will just instance one set in my possession, which answer admirably-viz., a wheel of 60 teeth (7 teeth per inch), for which I have pinions of 20, 22, 24, &c., up to 44 teeth. I may state that the angle of the master wheel was originally made to match the pinion of 32 teeth, which renders the divergence as small as possible. Since those were made I have also made a second master wheel of 50 teeth to match the same set of change pinions, so that nearly 30 different combinations can be got by means of those two wheels. To obtain so large a scope in this way, requires the teeth to be formed with great care, and the principle could not be applied beyond certain narrow limits in connection with wheels of a wide pitch.-MATRIX. [4040.]-WHEEL GEARING.-If "Kirby" will inspect the enclosed sketch he will be able to satisfy himself that he cannot gear a larger pinion with his bevel wheel. To construct the wheel a and pinion b first produce the axis of wheel a, and on a line at right angles to it, set off the diameter, which is 30in; next set off the radius of the pinion whose diameter is 10in., then from this point produce the axis of the pinion, which will cut the axis of the wheel at o; now this point must be the common apex of both cones, so that the outer and inner pitch circles shall be proportionate to each other, but to increase the pinion from to the size of the 10" a wheel we would have the inner diameter of the new pinion about 1 in. too large.-W. PROUDLOCK. [4041.]-BICYCLE QUERY.-I think that "Lerk's" benzoline lantern will not be of any service without he could with some contrivance suspend on springs, for it is the vibration that causes it to die out; nothing beats the proper composition candle lamp, with spiral spring and rocket. "Lerk" wishes to know which part of the foot is best to use on the treadle. It is a question I have long wished to have proved. I have been a bicycle rider now twelve months (witb never such plensure experienced before), and have tried both with the heel close to the treadle, and with the tread of the foot upon. For my part I ride and prefer the tread upon the treadle; and find less vibration, more use for the calves and ankles, and also reach a larger throw much easier. I am acquainted with a very fanciful rider who always rides with the tread; but he is the only one that ever I saw. I should much like another opinion (if proved) upon the matter.-VELOCE. [4043.]-CORNISH DOUBLE BEAT VALVE.-In answer to "F, P.," I send drawing of a 43in. valve from a Cornish engine at the East London Waterworks, at Old Ford. The valve itself is like a flat hat, with a hole in the top, and h two seatings, or "beats" as they are called, one round the brim and the other round the inside of the hole in the top. It is prevented rising too high by the plate at top of the guide piece in the middle, which is held on by screw bolts, and is likewise guided by being bored inside and fitted to the v tical edges of the 8 webs, of which 4 are shown. The top a cast open like a wheel with a large hole in the nave, so the when the valve goes up the water comes out, not only unde the lower edge, but also out through the holes in the tap These valves are very good where the lift is high, as the pres sure on them acts downwards only on the area of the alference between the outside diameter of the lower beat and the inside of the upper one, and as they are very heary P.S.-In reading "F. P.'s" query over again, I see he asks for an equilibrium valve, and as there is a steam valve of that name in a Cornish engine, I will describe that also. A Cornish engine is single acting only, and in piston only, when the piston gets say of the distance down the cylinder, the steam is cut off and acts expansively for the remainder of the distance. That is called the "indoor stroke," because the half of the beam next the steam is indoors, while the other end, at least in Cornwall, goes through a hole in the wall, and is consequently out-of-doors. Now the top and bottom of the cylinder are connected by a pipe closed at top by the equilibrium valve, and as soon as the indeor stroke is completed, the equilibrium valve is opened and a free passage given to the steam from the top to underneath the piston, and the outdoor stroke is made by the descent of a great load attached to the top of the plunger of the pump in waterworks engines, or in deep mines by the weight of the pump rods, which usually weigh several tons, and are sometimes partly balanced at intervals down the pit by great beams like steam engine; beams, which work in an excavation made in the side of the pit, and having a great box filled with old metal at the reverse end, and that pulls the piston up again. Direct action or " Bull" engines stand partly over the pit mouth, and the piston rod is attached direct on to the pump rods. Of course in them the steam acts under the piston. The construction of the equili brium valve is just the same as the pump valve, only has a rod to lift it. I have drawing of cataracts at "F. P.'s" service.-J. K. P. [4045.] SPECTACLES.-In answer to "J. R. W.." allow enough, or else there is some other defect in his eyes, for if me to say that he has not got his concave spectacles concave his spectacles were properly chosen he ought to be able to recognise a person 30 yards off, and not 3 yards only. Let him buy a more concave pair of spectacles. As to things looking smaller through concave or shortsighted spectacles, this he he must expect, for the fault of shortsighted people's eyes is that they make things look too large, or bring the rays of light to a focus before they reach the retina or back part of the eye. Concave spectacles diminish the apparent size of things, or in other words throw back the focus of the eye to the retina. This apparent smallness of objects seen through concave spectacles will wear off in time, and he will get to take no notice of it. enough, he had better see to getting a pair that are wide As to his spectacles not being wide enough, as he will have to get another pair more concave to silver soldered on to the ends of the sides of the new specsuit his short sight; further let him have some bits of wire tacles so that he can bend them to fit the backs of his ears, this is much better than jointed sides to turn behind the ears as the joints wear loo se and soon become of no use; I have had mine so made, and they answer better than any other plan I have tried, especially for "J. R. W." who is so short-worts, bringing them down far enough to prevent secondary sighted as to have to wear spectacles constantly. He then can jump and run, and lay down without the spectacles falling off his nose, and, lastly, there would be very little advantage in having plauo-concave instead of double-concave glasses, so small as not to counteract other disadvantages.-H. W. A S. [4015.]-SPECTACLES.-The object of spectacles is to restore the eye as nearly as possible to its original power. "J. R. W.'s" eyes magnify too much he requires a concave spectacle to counteract this defect. He says the spectacles he has make objects appear seven-eighths their real size; it is evident they are too concave. Spectacles a little less powerful would remedy this and make his eyes ache.-OPTICS. [4053.J-DRYING GLUE.-J. S." must understand that the mere putting of the air in motion will not dry his gle. It is a fact that air of any given temperature, although saturated with moisture (and in that condition, as a matter of course, useless for drying purposes), becomes capable of absorbing additional moisture in proportion as its temperature is raised, so that "J. S." if he wishes to go scientifically to work must have some means of securing a constant influx of air from a comparatively cool medium, heating it on its passage inwards, as much as practicable, then exhaust it, or allow it to escape as near as possible at the opposite extremity of his room. This can either be done by means of a small fan, or by means of an ordinary fire with a good high opening at the chimney-even two or three windows open at the top-or, still better, ventilators, might answer the purpose, assuming that the temperature has been raised considerably before passing into the room. No good will be done without an in and out current of air.-MATRIX. [1054)-MICROSCOPIC INVESTIGATION WITH PO LARISED LIGHT.-I do not think that polarised light wil be of any service to "John Barleycorn" in his investigation into the development of the Torua cerevisiae or yeast fungus. All that he will require for that purpose will be a good or in. and A or B eyepieces with or without a "condenser." Examination of acetic acid is more the work of the chemist than the microscopist, but it is convenient to call the aid of the microscope into requisition sometimes that reactions in minde quantities may be observed. For general polariscopic investigation no apparatus can better answer the purpose than "Nichol" prism below the object as a polariser, and a second prism used above the objective as an analyser. This latter prism may be conveniently made so as to be capable of use in this position or above the eyepiece. But in work I find the former position the preferable one. Want of time prevents my going into detail, but if "John Barleycorn" wishes and the Editor will allow, I will give a few general hints in a week or two.-H. P. [4061.]-ASSOCIATE OF ARTS DEGREEE. - Every candidate for the title of A. A. must be under 18 years of age on the day of examination. He must pass a preliminary examination in (1) grammar and analysis; (2) English composition; (3) arithmetic, including fractions; (4) geography; (5) the outlines of English history. Failure in any one of these five subjects is absolutely fatal, however high a candidate may stand in the examination I now describe. The other part of the examination is divided into four sections:A English, B languages, C mathematics, and D science. Every candidate, in addition to the preliminary, must pass in two of the divisions, A, B, C, and D. Each of these divisions is divided into sections, and superior answering in one of these sections, will pass a candidate in the division. Division A is divided into four sections:-(1) English history-a certain period given beforehand. (2) Political Economy; (3) English Literature-certain authors; (4) Geography. Division B: (1) Latin; (2) Greek; (3) French; (4) German. The minimum for division C is four books of Euclid and algebra to quadratic equation inclusive; D (1) Natural Philosophy; (2) Chemistry; (3) Botany; (4) Geology and Mineralogy. Nearly all candidates take division A English, as they are obliged to take history and geography in the preliminary. So that in additiou to this, one language, or chemistry; or the minimum of mathematics will pass a candidate. I passed in honours in two divisions. The examination is conducted by the University of Oxford, at various local centres in the country, such as Leeds, Manchester, &c. The fees which I paid amounted to £2.-J. HARRISON, A. A., Bradford. [4064]-TURBINE. PATTERN MAKER."-A turbine wheel giving out 1 h.p., will require some 35 cubic feet per minute under a head of 20ft. To determine size of pipe, it will be requisite to know the pressure acting upon such column, after which a large per centage must be allowed for friction. A turbine will be more economical and efficient than a steam engine and boiler. Try the North Moor Foundry Company, Oldham, they supply small machines to utilise a town's water. I have just put in Messrs. Spon's (the publishers) hands a thoroughly practical work upon turbines, for the use of all who wish information respecting them. J. GILLAIRD, action or fermentation. Is the whole brewery thoroughly clean and sweet, if not, wash out and lime at once. These are a few very imperfect jottings and thrown together in a very hurried manner; yet "Brewer" may get some good from them, and I shall be glad to assist him or any other; only to do so with anything like a prospect of success, 1 must have more particulars. Every brewer will understand this. -IzOKS, Edinburgh. [4067.]-MUSICAL BOX.-The cause of the musical box making the jarring noise he complains of is probably that some of the fine springs underneath the notes are broken off. I have had one or two lately brought me to repair with the same complaint and shall be happy to undertake" Salopian's" if he thinks proper.-E. BARNARD. [4068.]-PRESERVING FLOWERS.-If "G. O. F." wishes to dry flowers so as to make them resemble everlasting, as in the beautiful bouquets sent over from our German friends, the process is somewhat as follows: Procure an apparatus which may be made of zinc, and cylindrical in shape, open at both ends, and with a perforated diaphragm (as shown in sketch in section), a cover or lid is also provided for each end. Suppose the box to measure 10in. in length by 4in. diameter. Sufficient very fine silver sand, thoroughly cleaned from dust by frequent washings in water, dried, and well shaken up, whilst in a heated condition with a small quantity of spermaceti, which is held in readiness. The cut as flowers are now dropped gently into the box by the end B so to rest upon the diaphragm C, the box being inverted. When filled the lid is replaced at B, and the apparatus turned up, as represented in sketch. After removing the cover A, the cool sand is caused to percolate through the perforations until the whole insterstices between the flowers, and also the space above the diaphragm are completely filled. After replacing the lid the apparatus may be placed in an hausted oven overnight, being careful to have the lid B placed loosely on the top. The sand supports the flowers and preserves the integrity of cation, and the spermaceti is evidently intended to prevent the petals during the process of dessithe sand from adhering to them through the influence of the lid A is removed and the sand allowed to escape which is When the dessication is completed of course available for future ope rations.-MATRIX. [4071.]-DRAUGHT IN BOILER. "Jonath" says the flue of the chimney has been repeatedly swept, but I feel quite sure it does not get thoroughly cleaned. Let "Jonath" mind and see the sweep's machine through the chimney top; in fact he must be sure to see that the flues throughout, from the fire to the chimney top, be thoroughly cleaned with a really good stiff whalebone brush; the inside of tubes or flues makes nothing but what a stiff brush will scrub out; the incrustation inside the boiler has nothing whatever to do with the draught of the flues. I believe some part of the chimney or flues are almost blocked up with soot; let the bottom of the old flue or chimney be bricked up.-ANDREW JOHNSON. [4078.)-RAILWAY GUARDS' WATCH. From long practical experience I do not hesitate in stating my belief that pocket chronometers are a mistake. "Railway Guard" would find, if he had one, were it ever so good, that if he ran the distance of the length of a train with a chronometer in his pocket that the shaking would cause it to vary seconds, and that it would be some time before it would recover and get back to its rate again. My opinion is that a thoroughly good English lever with about ten holes jewelled and a chronometer balance costing in silver cases £8 to £10 is as good a pocket timekeeper as could be desired. If necessary, I could tion-masters, cler6s and others who carry these identical give "Railway Guard" names and addresses of railway stawatches and from long use have proved them to be thoroughly reliable.-CHRONO. B the heat and moisture. ex [4082.]-FLUTE-If Mr. O'Brien will take my advice, he will keep his flate as it is. The difference in pitch is surely not a fault, and can only be inconvenient if he wants to play with another instrument of the present concert pitch. Nevertheless, if he persists in having it altered, he should apply at Rudall's, Chiaring-cross. They will tell him whether they can do it, and will give him honest advice in the matter. Further, they will not charge more than some of those needy houses who are ever ready to alter ins truments to order, without caring whether they improve or spoil them.-SAU RYMEA. Richard L. for his French kingdom of Poitou. It bears on the obverse, a cross patée and RICARDVS REX (Richard, King). Reverse, the hame PICTAVIENSIS (Poitou) in three lines. This coin is common, and worth ab3s. if in fine preservation. The series, to which this b ugs, of coins struck by English princes in France, is tern the AngloGallic; and it includes pieces of Aquitaine, vitou, Bourdeaux, Calais, Paris, Caen, Tours, Limoges, Ants rp, Bruges, Ghent, Ypres, Tournay, etc., embracing also almost every part of France.-HENRY W. HENFREY, M.N.S., &c., &c. [4095.]-SILVER COINS.-The largest silver coin is a penny of Richard I. There are no English coins of this king, this coin was coined in Poictou, (Pictairensis on the reverse). They were formerly very rare, but not so now. as hordes have been found. The small coin of no interest Should be glad if " A Beginner" would correspond with me, that I may have his address.-W. NELSON LAST, Bury St. Edmunds. [4095.] SILVER COINS.-No. 1 is of a Doge of Venice (Leonard Loredano?); the name is just where the letters are not given: on one side the Saviour and " LAUS TIBISOLI," "praise to Thee alone." Reverse, S. Mark and the Doge." "Dux. S.M.V." Doge, S. Mark, Venice. No. 2 I read "KAROLUS REX FR."; rev. PICTAVIENSIS, and think it is of Charles II. King of France, and struck at Poictiers.-BERNARDIN [4097.J-A VELOCIPEDE FOR SPORTSMEN.-See reply amongst the letters. [4100].-SWAGING SCREWS.-If " Amateur Blacksmith " does not want an oliver to forge his set screws and bolts he could easily make some swaging tools. If he wishes to make hexagon heads to his bolts he will require an extra set of tools; but they are inexpensive if he goes the right way about it.-J. M. [4105.]-HALL MARKS.-The best book on the hall marks is Hall Marks on Gold and Sliver Plate," by W. Chaffers, F.S.A., 3rd edition, price 3s. 6d., published by J. Davy and Sons, 137, Long Acre, London. It is a most useful book, and gives tables of the date, letters, and marks of every assay office in the United Kingdom, from the earliest period of their use to the present day, with fac-similies, and a mass of valuable informarion.-HENRY W. HENFREY, M.N.S.; &c. [4106.]-GOLD COIN OF EDWARD I1I.-In asking the value of a quarter-noble of Edward III, I presume that Casteye Diamond "means one of his fourth issue, in the 21st and following years of his reign, which bears, obverse, a tressure (or border) of eight arches pointed with trefoils, containing the royal arms in a beaded shield. EDWARD. DEI. GRA. REX ANGL. (more or less abbreviated). Reverse, a tessure of eight arehes with fleur-de-lis and lions alternately in the angles, containing a cross fleurée. Sometimes E in the grains troy. centre. EXAL TABITUR IN GLORIA. Full weight, 30 This coin is common; worth 12s. to 15s. Other quarter-nob les of preceding issues are rare, and weigh several should be much obliged if he would kindly send me a sealgrains more. If "C. D.'s" coin weighs more than 30 grs. ing-wax impression by post. HENRY W. HENFREY, Markham House, Brighton. [4108.]-COIN OR TOKEN.-Is a halfcrown of what is termed "Gun Money," and was coined on account of the exigencies of James the 2nd when in Ireland; crowns, shillings, and sixpences were also struck in the same metal, and bear dates 1689 and 1690. They were coined from old brass guns. For particulars, see "Simon's Essay on Irish Coins." They form a very interesting collection, as they were struck with the name of the month on them, this was struck in August, 1689.-D. T. BATTY, 9, Fennell-street, Manchester. [4108.]-WHAT COIN IS THIS?-It is a gun money half crown of James II. The following extract is from my "Guide to English Colns," part ii, p. 112:-" When James landed in Ireland in March, 1689, to attempt the recovery of his dominions, he resorted to several expedients to remedy the scarcity of money in that kingdom. First of all, the value of the guinea, as being of easier carriage than the silver money, was raised one-fifth, or 20 per cent., whilst the silver coins were raised no more than one-twelfth, or 83 per cent., and other foreign gold and silver in proportion, that what money he could obtain might go a greater way. However, as all these expedients failed to proeure a sufficient supply of money, he coined brass and copper sixpences, which were made current by a proclamation dated June 18th, 1689. Half-crown's and shillings were soon after added; made current by proclamation 27th June. Crown pieces of white metal were ordered to be and brass previousy issued, were called in in June, 690, recurrent on the 21st April, 1690. The half-crowns of copper stamped with the die of the crown, and issued at the value of stop to these base coinages, which derived their name of "gunfive shillings. The battle of the Boyne, on July 1st, put a kitchen utensils, &c." XXX. signifies thirty pence, the value, money" from being made of brass cannon, brass and copper and "Aug.' the month when it was coined. The shilling and sixpence are exactly like your correspondent's half-crown, of all three, 6d. to 1s. each. -HENRY W. HENFREY. except that they have "XII." or "VI." for the value. Value question of our friend "Algebra " is just one of those which [4118.]-PROBLEM-THE FOLLY OF ALGEBRA.-The problem is, "A gentleman having mortgaged an estate for may well prove how unnecessary is his science itself. His knowing in what time he shall discharge the said debt and £2000 at 5 per cent. compound interest, he is now desirous of interest by paying the mortgagee of £187 yearly." Here is "Algebra's" usual flaw. There need not be any compound interest! Compound interest pertains only to such a case as when perhaps à reversion is purchased in advance; or again when nothing is to be paid till a reversion or life-policy becomes available. In such a transaction, no money is paid year by year; there is a lump sum, either at the beginning or at the end. But here the mortgagee gets £187 yearly. The 5 per cent. on £2000 would be only £100. Therefore, any bookkeeper, any solicitor, any accountant, any actuary, would 5 per cent. annual interest. I am well aware that our friend simply take £100 out of the £187, as (regularly) paying the Algebra" wants the "£2000 at 5 per cent. compound inteto go on accumulating, in order that there may be a more tortuously big total to be met by the £187. But, there need not be any such accumulation. There never would be in plain fact, in the very case supposed. The intended complication is only a riddle for riddle sake; it is mere x, mere algebra, mere gratuitous muddle, mere needless self-mystifidischarge the said interest?" My reply is, the interest shall cation. So, to one half of his query, "in what time shall he be discharged annually, out of the £187. Then, as to the second question, we see there would remain £87 per annum; this would be a sinking fund paid to the mortgages, and this accordingly ought to fructify at compound interest, say 5 per a "Beginner" is a silver denier or penny, struck by our Kingcent. Thus the awful problem of "Algebra," when popped about ten inches long and three-quarters of an inch in To be placed in a glass phial sealed.-GIMEL. diameter, nearly filling the phial, which is to be hermetically [4066.]-BREWERY.-" Brewer's" temperature is not too low. I pitch my mild ales at 56 °, and, as a rule, succeed in getting them quite bright. It is very difficult for one who knows nothing about the position or arrangement of his brewery to give a proper explanation, as there are so many 4086.]-FITZROY STORM GLASSES.-These are to be different systems in use, and therefore a great many points had so cheap that they are hardly worth the trouble of makat which a wort could be affected. I will not presume to pointing, and as weather guides they are perfectly useless. I have out to "Brewer" the cause of his ales not clearing (unless tried several. I have had one undisturbed in my summer I was intimately acquainted with all details concerning his house for two years, but its indications are so wild and place, and the system he works on). But the mode of pro- contradictory that there is not the slightest dependence upon cedure I follow, when troubled in any way as he is, may it, and I only retain it for the barometer attached.-AMATEUR. assist him in getting to the bottom of his difficulty, and [4086.]-FITZROY STORM GLASS.-The composition is perhaps discover to him where the evil lies. I examine the water and see if there is anything in it deleterious, then the sium, half a drachm of chlorate of ammonium, dissolved in two drachms of camphor, half a drachm of nitrate of potasmalt, as to its being thoroughly dry and free from mould, about two ounces of absolute alcohol mixed with two also see that it is properly crushed, not too fine. I am also ounces of distilled water. very careful in washing, using the liquor of a proper heat. say 170° to 1689, taking care always to have the goods fal ng into the mash tun abou 150°; this gives me a tap heat of 144° to 148, according to the age of the malt (I like it two months old at least). I watch the copper well, and amis quite right in his correction. The fact is it ought to be [4089.3-READINGS FROM THE GLOBES.-" Gimel " careful in not raising it to the boil too quick, then a steady 9 instead of 94, which will bring out 43 miles nearly. and regular boil of 14 to 24 hours, according to the hardness of the brewing water and the gravity of the worts, then the most accurate way is by trigonometry and logarithms, as blow off the steam on the coolers till about 180 or 1900, stated.-T. S. H and do not use too much water in refrigerating, but run regular and not too strong; see to yeast, its freshness, quality, and freedom from all taint or smell; use 1lb. or 1lb. per barrel for mild; use the tuns or gyles clean and sweet, and free from all mixtures of metal or anything likely to cause the least galvanic action or electric current, then great care is requisite in the working off of the gyle tun, which a long practice can only bring to perfection; taking care not to check too quick or yet raise by any artificial means the heat of gyle, and above all watch the proper attenuating of the But It is of no [4094.]-COPPER COIN.-The coin of "N. T. M." is one of the common Nuremburg tokens, of which accounts have been given so often in the ENGLISH MECHANIC. value.-HENRY W. HENFREY, M.N.S., &c., &c. [4094]-COPPER COIN.-Is a counter or abbey piece, struck probably, as Snelling thinks, between 1272 and 1500. "N. T.M." must look into back numbers, where he will find authorities given.-D. T. BATTY. [4095.]-SILVER COINS.-The second and largest coin of rest |