SCIENTIFIC SOCIETIES. Tisst excursion for and the neighbourhood. of atoms is, as far as chemistry is as yet advanced, arrives at the conclusion that the difference of pres- nature of some other peculiar products formed in a theory. sure needed to produce an explosion capable of addition to alizarine, which render the artificial If, however, the existence of atoms cannot be projecting a prominence to the height of 3 minutes colouring matter different from natural alizarineproved by chemical phenomena, we must remember above the sun's surface is 4,070,000 atmospheres. has been carried out by Mr. Perkin, and especially that the assumption of the atomic theory explains This enormous pressure is attained at a depth of by Dr. Schunck. The Professor next referred to chemical facts, as the undulatory theory gives a 139 geographical miles under the sun's surface, or the process of recovering sulphur from the vat clear view of the phenomena of light; thus, for in- at that of the 1-658th part of the sun's semi-dia- waste. Dr. Mord had now satisfactorily solved the stance, one of the most important facts and rela-meter. In order to produce this gigantic pressure, difficult problem of economically regaining the sultions of modern chemistry, which it appears diffi- the difference in temperature between the enclosed phur by oxidizing the insoluble monosulphide of cult if not impossible to explain without the as- hydrogen and that existing in the solar atmosphere calcium in the lixiviating vat itself to the soluble sumption of atoms, is that of Isomerism. How other amounts to 74,710° C. In a similar way Zollner hyposulphite, and decomposing this by hydrochloric wise than by a different arrangement of the single calculates the approximative absolute temperature acid, when all the sulphur is deposited as a white constituent particles are we to account for several of the sun's atmosphere, which he finds to be powder. He also alluded to Mr. Weldon's process distinct substances in which the proportions of car- 27,700° C.; a temperature about eight times as high of recovering the black oxide of manganese used bon, hydrogen, and oxygen are the same? Why, as that given by Bunsen for the oxyhydrogen flame, for the evolution of chlorine in the manufacture of for instance, should 48 parts, by weight, of carbon, and one at which iron must exist in a permanently bleaching powder. Another process, which may 10 of hydrogen, and 16 of oxygen, united together, gaseous form. possibly still further revolutionize the manufacture be capable of existing as three different chemical of bleaching powder, was that discovered by Mr. substances, unless we presuppose a different statical Deacon for the direct production of chlorine from arrangement of the parts by which these differences hydrochloric acid without the use of manganese. in the deportment of the whole are rendered possible. If, then, it be true that chemistry cannot give us positive information as to whether matter is infinitely divisible and therefore continuous, or consists of atoms and is discontinuous, we are in some degree assisted in this inquiry by deductions from physical phenomena which have been recently pointed out by the genius of Sir William Thomson. He argues from four different classes of physical phenomena, and comes to the conclusion not only that matter is discontinuous, and therefore that atoms and molecules do exist, but he even attempts to form an idea of the size of these molecules, and he states that in any ordinary liquid, transparent or seemingly opaque solid, the mean distance between the centres of contiguous molecules is less than 100 millionth, and greater than the 2,000 millionth of a centimetre. Or, to form a conception of this coarse-grainedness, imagine a raindrop, or globe of glass as large as a pea, to be magnified up to the size of the earth, each constituent molecule being magnified in the same proportion, the magnified structure would be coarser grained than a heap of small shot, but probably less coarse grained than a heap of cricket-balls. There is, however, another class of physical considerations which renders the existence of indivisible particles more than likely. I refer to the mechanical theory of gases, by means of which, thanks to the labours of eminent English and German philosophers, all the physical properties of gases-their equal expansion by heat, the laws of diffusion, the laws of alteration of volume under pressure-can be shown to follow from the simple laws of mechanical motion. This theory, however, presupposes the existence of molecules, and in this direction, again, we find confirmation of the real existence of Dalton's atoms. Indeed, it has been proved that the average velocity with which the particles of oxygen, nitrogen, or common air are continually projected forwards amounts, at the ordinary atmospheric pressure, to 50,000 centimetres per second, whilst the average number of impacts of each of these molecules is 5,000 million per second. No opinion would appear to have been more firmly established than that of the existence of three separate states or conditions of matter, viz., the solid, the liquid, and the gaseous. A body capable of existing in two or more of these states was thought to pass suddenly from one to the other by absorption or emission of heat, or by alterations of the superincumbent pressure. Dr. Andrews, of Belfast, has shown us how false are our views on this fundamental property of matter, for he has proved that a large number of, and probably all, easily condensible gases or vapours possess a critical point of temperature at and above which no increase of pressure can be made to effect a change into what we call the liquid state, the body remaining as a homogeneous fluid. Whilst below this critical temperature certain increase of pressure always effects a separation into two layers of liquid and gaseous matter. As examples of the power which modern methods of research give of grappling with questions which only a few years ago were thought to be insoluble, I may quote the beautiful observations by which Lockyer determined the rate of motion on the sun's surface, together with those of Frankland and Lockyer respecting the probable pressure acting in the different layers of the solar atmosphere; and, astly, the results obtained by Zollner respecting solar physics and especially the probable absonte temperature of the sun's atmosphere, as well as that of the internal mass. Starting from he fact of the eruptive nature of a certain class of solar protuberances, Zöllner thinks that the extraordinary rapidity with which these red flames shoot orth proves that the hydrogen of which they are nainly composed must have burst out from under great pressure; and if so, the hydrogen must have been confined by a zone or layer of liquid from rom which it breaks loose. Assuming the existence of such a layer of incandescent liquid, then apply ng to the problem the principles and methods of he mechanical theory of gases, and placing in his ormule the data of pressure and rate of motion as bserved by Lockyer on the sun's surface, Zollner * See ENGLISH MECHANIC, Vol. XI., p. 577. Passing on to more purely chemical subjects, we find this year signalized by the redetermination of a most important series of chemical constants, viz., that of the heat of chemical combination by Julius Thomsen, of Copenhagen. This conscientious experimentalist asserts that the measurements of the heat evolved by neutralizing acids and bases hitherto considered most correct, viz., those made with a mercury calorimeter by Favre and Silbermann, differ from the truth by 12 per cent.; whilst the determination by these experimenters of the heat of solution of salts is frequently 50 per cent. wrong. As the result of his numerous experiments, Thomsen concludes that when a molecule of acid is neutralized by caustic alkali the heat evolved increases nearly proportionally to the quantity of alkali added until this reaches 1, 1, 1, of a molecule of alkali, according as the acid is mono-, di-, tri, or tetrabasic. A second unexpected conclusion which Thomsen draws from his calorific determinations is, that sulphuretted hydrogen is a monobasic acid, and that its rational formula is therefore HSH. Another important addition made to chemistry is a new, very powerful, and very simple form of galvanic battery, discovered, though not yet described, by Bunsen. In this second Bunsen's battery only one liquid, a mixture of sulphuric and chromic acids, and therefore no porous cells, are employed. The plates of zinc and carbon can all be lowered at once into the liquid and raised again at will. The electromotive force of this battery is to that of Grove (the most powerful of known forms) as 25 to 18; it evolves no fumes in working, and can be used for a very considerable length of time without serious diminution of the strength of the current, so that Bunsen writes me that no one who has once used the new battery will ever think of again employing the old forms. Amongst the marked points of interest and progress in inorganic chemistry, we have to notice the preparation of a missing link amongst the oxysulphur acids by Schützenberger. It is the lowest known, and may be called Hydro-Sulphurous Acid, H2 SO. The sodium salt, Na H SO2, is obtained by the action of zine on the bisulphite. As might be expected, it possesses very powerful reducing properties, and bleaches indigo rapidly. As an illustration of the results of modern organic research, I may quote Baeyer's remarkable investigations on Mellitic Acid. Originally discovered by Klaproth in honeystone or mellite (a substance which yet remains the only source of the acid), mellitic was supposed to be a four-carbon acid. Baeyer has quite recently shown that the acid contains twelve atoms of carbon, or has a molecular weight three times as great as was originally supposed. OSWESTRY NATURALISTS' FIELD CLUB. HE last excursion for the season was made by The members and their friends proceeded to the quarries worked in the outlier of the carboniferous limestone at Hafod-y-Calch. Beautifully preserved remains of the life of that period were found occurring in extraordinary profusion, one bed being an old sea-bed, made up exclusively of coral, molluscous and fish remains, which were speedily transferred to the bags of the geologists as far as their capacity would allow. Among the fossils found here, special mention should be made of an ichthyoduralite, the defensive bone of a large fish which appears to have been the master of those ancient seas. Streptorhyncus crenistria, a beautiful bivalve shell; Phillipsastrea radiata, a rather rare coral, and three good forms of delicate Bryozoon life. A pleasant walk of about a mile along the banks of the Dee brought the party to Cynwyd, where they began to ascend the western side of the Berwyn hills to the Silurian rocks, containing Trilobites and other fossils, described in the paper by Mr. Parrott, "On the Fossiliferous Beds of the West Flank of the Berwyn Range, near Cynwyd, Merionethshire." "During one of my Saturday geological explorations in this delightful part of ancient Siluria, I found my labours rewarded by the discovery of a very productive and rich upper Bala deposit, lying in well-marked zones on the hill sides skirting the north and east of the little valley of the Afon Trystion, which discharges itself into Deva's farfamed waters at the little village of Cynwyd. small stream rises in an amphitheatre of hills, which I have no hesitation in saying may prove of great interest to the geologist. The organic remains are unusually well defined, and the series in each stage or zone are numerous in genera and species. This The Trilobites are well represented, and the list of species at present brought to light outvies even the prolific catalogue of forms found by the Geological Survey at Rhiwlas, near Bala. Minor faults occur here and there in the Trystion valley under consideration, and these, coupled with the effect produced by the great internal dislocation alluded to, have unquestionably rendered extremely difficult a really true demonstration of the disturbed features of this part of Merioneth." To attempt to describe the local features of the strata in the neighbourhood of Cynwyd, or the ground betwixt that place and Corwen, would be a really puzzling task; the intricacies of the lines of bedding, the strong flexures in the dip and strike, The Professor then passed in rapid survey the and the singular contortions we here and there more important discoveries in the field of chemistry, meet with, plainly show that we are on troubled such as the researches of Matthiessen and Wright on ground, no doubt in a great measure the effect of the constitution of the opium alkaloids, during one great and principal fault, which takes the line of which it was found that morphine, treated with the valley of the Dee from Corwen through Bala hydrochloric acid, gives up one molecule of its lake, and onward to the vale of Talyllyn and Towyn, water, and becomes a totally different substance-I mean the great Yale and Bala fault. under the name of apomorphine. An important application of the dehydrating and carbon-condensing power of zinc chloride, long known in its action on alcohol to produce ether, has been made by Kekulé; whilst the discovery of the sedative properties of chloral hydrate by Liebreich marks an era in medical chemistry second only to the dis covery of the anesthetic properties of chloroform. The chemistry of colouring matters has lately received an enormous impetus in the practical working of the brilliant discovery of the production of artificial alizarine, the colouring matter of madder, by Messrs. Graebe and Liebermann. This discovery is of the highest importance, whether we regard its scientific interest or its practical and commercial value, as it has reference to the artificial production of a natural vegetable colouring substance, which has been used as a dye from time immemorial, and which is still employed in enormous quantities for the production of the pink, purple, and black colours seen everywhere on printed calicoes. Much progress has been made in the practical working of the processes by which this colouring matter is obtained from the hydrocarbon anthracene contained in coal-tar, and new and more economical plans for effecting the transformation have been independently proposed by Perkin and Caro and Schorlemmer and Dale. The theoretical investigation of the reaction-and especially of the The author then described the various reefs or zones of fossils which he had marked on a chart of the district, enumerating the species found, which include, amongst numerous others, Calymene brevi capitata, Phacops apiculatus, Ampyx nudus, Lichas laratus, Cybele verrucosa, Illenus Davisi, together with several unnamed or undetermined species. In one zone the author found rare and beautiful specimens of Echinosphærites and Pleurocystites, also very many forms of Brachiopoda, Lamellibranchiata, Cephalopoda, and unique specimens of Murchisonia of several species, all in good condition and easily separated from the matrix. Mr. Parrott then described the lithological character of the beds in which the fossils are found, and thus concluded:-"As the mountain region described in the present paper is but a small part of a large tract in this part of Merionethshire, which has been only just glanced at by the last Government survey, but which really merits further research, I shall feel very glad if my humble explorations in this district may induce my brother geologis ts to take the matter up, and endeavour to clear up a have the truth. But I would submit that neither Prof. constructed a small windmill on this principle and it works admirably. THE FRICTION CLUTCH. R. B. few of the more important points, so feebly and unscientifically hinted at in this description of the new fossil beds of the picturesque valley of the Trystion. More than one veteran geologist has (when shown specimens of the organic remains of this district) been led to exclaim, Truly these are wonderful beds! what a rich field for a palæontologist! what a boon to science!' and the small selection of specimens from my cabinets brought forward this day to illustrate my paper, will bear gress of discovery, still less to assign to each person fore take the liberty of enclosing for the information out the above remarks, coupled with a hope that ere long I shall find helping brethren willing to wield the hammer and guide the chisel in endeavouring to disentomb the hidden remains of an ancient and most interesting world of life." LETTERS TO THE EDITOR. [We do not hold ourselves responsible for the opinions of our correspondents. The EDITOR respectfully requests that all communications should be drawn up as briefly as possible.] All communications should be addressed to the EDITOR of the ENGLISH MECHANIC, 81, Tavistockstreet, Covent Garden, W.C. who has advanced scientific research his proper degree Undoubtedly some one is to blame, and that seriously, All Cheques and Post Office Orders to be made pay-perly) taken the historical facts at second-hand, and able to J. PASSMORE EDWARDS. "I would have every one write what he knows, and as much as he knows, but no more; and that not in this only, but in all other subjects: For such a person may have some particular knowledge and experience of the nature of such a person or such a fountain, that as other things, knows no more than what everybody does, and yet to keep a clutter with this little pittance of his, will undertake to write the whole body of physicks: a vice from whence great inconveniences derive their original."-Montaigne's Essays. In order to facilitate reference, correspondents when speaking of any Letter previously inserted will oblige by mentioning the number of the Letter, as well as the page on which it appears. SCREW POWER. [398] SIR,-In a letter 340, p. 592, on this subject, "J. K. P." makes a statement calculated to frighten young students of mathematics from attacking the differential calculus. He says the differentiation of tan i cot (i + ) takes the whole side of a sheet of letter-paper, some of the steps being too long to be got into the space even when written lengthwise of the sheet. This is amazing. The whole process for determining when tan i cot (i+p) is a maximum, is as follows: Equating the differential coefficient (with respect to i) to zero, we have [402] SIR,-Lull's improved friction clutch (309, P. 596) is a very clever and most ingenious contrivance, but unfortunately comprises too many parts, and too much skilled workmanship. I there. unfortunately from some work in which those facts are [400] SIR,-I may as well point out' with reference to the letter of "J. W. A." on this subject (393, page 617), that the discoveries of the last few years have proved that meteoric bodies come neither from the sun nor moon, that is, all these bodies which we can observe under such conditions as to be able to determine their orbits, have been proved not to come from the sun or moon. So that we do not get out of our difficulties by adopting the explosion theory, since it is certainly not applicable to all meteors. No astronomer, let me add, believes it to be applicable to any. WINDMILL FOR TURNING, PUMPING, ETC. hand an engraving of a novel description of wind-rately turned to fit previous to cutting the interior into the four segments and forming the slots to receive the projections in the periphery of the piston disc. Also to have especial regard to the four links, so that they sin 2 sin & sin (2 i + ) + cos p shall be almost, but not quite in a line, when the sliding tubular piston is sent home to work. This contrivance is not protected by patent right, and, consequently has not, and cannot be taken up by the trade, though I have long since made it known. HENRY W. REVELEY. SPECTRUM ANALYSIS. [399] SIR, Mr. Nugent has done good service (letter 362, page 611), in correcting the statements commonly made respecting Newton's optical researches, &c. It is undoubtedly well that in such matters we should STOCKS AND DIES. [408] SIR,-I send a description of a new invention I have seen at the inventor's (Mr. Leeches, Goat-lane, mill which I remember seeing in operation at the Norwich). It consists of patent stocks and dies, also Paris Exhibition, 1867. The construction is exceed-tube-cutter all in one, for screwing and entting iron ingly simple, and your correspondent could easily pipe from in. to 2in., also iron bolts. adapt it to his purpose. I may mention that I have ment takes the place of six different ones now in use, This instru 2. DIE viz., three stock and three pipe cutters. The drawing, I send is a copy of patent stocks; Fig. A showing stocks ready for use, H H are the handles, N N nuts for tightening alms, I I alms to fit on handles, P P pins to fit in the holes S S; Fig. O wrench for nuts, Fig. C tube cutter, Fig. B 2in. dies; when reversed K K are two tap wrenches, Fig. D case for stocks, which is 24in. over. There are three sets of dies, in which there are three tap wrenches, one tube-cutter which cuts all the sizes. The stock complete weighs only 61b., where the old stocks weigh 221b., which answer only for 2in. pipe. They are the best I have seen yet. I myself have worked them, also seen the men cut up dies in them, and thus experienced what they will do, especially on 2in. pipe, both screwing and cutting. The dies are so made that they will work quicker than the ordinary ones, and require only one person or boy to use them, where the old ones take two men to work them, which causes a great deal of labour which might De done away with. G. YOUNGMAN. [404] SIR, "E. O. S." (see 336) is puzzled, as many before him have been, by taking the case of parallel rays from an infinitely distant point, or an astronomical object, and confusing such rays with the case of parallel rays issuing from different points of the same object; and also by not having a clear comprehension of the meaning of the word focus. Focus does not mean the point in which rays coming from different parts of any object happen to cross each other, but it means the point in which several rays issuing from the same point of any object are made to converge. If each different point of a body gives off several rays, then there will be a plane of points where the different rays severally converge. By the above diagram, it will be seen that rays from different points of any object cross each other at almost an infinite number of points; but that rays from the same point converge only in one point: that one point is the focus, and a plane of such points is a focal plane. No distinct image can be formed except in the focal plane. If "E. O. S." will refer to his Fig. 1, p. 591, he will see that if A B C mean rays from different points of a body, then Fis not the focus; but merely one of the many points where several rays happen to cross each other, but if A B C mean parallel rays from the same point of a very distant body, such as the sun, then F, where such rays converge, is the focus. T. M. SIMKISS. READINGS FROM THE GLOBES.-XII. [405] SIR,-In every branch of science there are certain technical terms which, when used, seem to imply a difficulty in that science, which in some cases may discourage from its pursuit, but when they have been explained, the road often becomes easy; and able to find the latitude, longitude &c.-things most important in navigation; for if we make the sun's place in the ecliptic coincide with the rising amplitude, 54° north of east, the elevation of the pole will show the latitude; or we may work it thus: if we thoroughly understand how to measure angles and sides by the globe (see remarks on page 372), we shall see two right angled globular triangles, formed as in Fig. where A B is the latitude, ACD the wooden horizon. As we are supposed to know two things, namely, the sun's longitude and the sun's oblique ascension, we must bring these two points to the horizon, A and we shall see the amplitude and the latitude, the amplitude on the horizon and the latitude in the elevation of the pole; or bring the oblique ascension to the east point of the horizon, and elevate or depress the pole until the other mark, namely the sun's longitude, coincides with the horizon, and we shall find the latitude, &c. By referring to the figure, it will be seen that several most important things are thereby known-namely, the amplitude, coamplitude, the latitude, the colatiude, the declination and the codeclination, and hence the longitude by referring to the chronometer. Thus the globe will show these several things at once, but it will be advisible to verify them by the formulæ in trigonometry, and daily practice renders calculations by this method as familiar to the navigator as the simplest process in arithmetic. In the lower triangle we have two sides, and an angle-namely, A D the ascensional difference, and A C the declination 23°, and we can thereby find the angle A D C, which is the colatitude; angle we have given the two sides, B C the codeclination also the side D C, the amplitude; and in the upper tri66, and A C the coamplitude, the angle at A being the right angle, hence the formula is cos AC: cos BC R: cos AB, which will give 60° 18' as the latitude, and in the lower triangle the formula is sin A D: R:: tan AC: tan D, which gives the colatitude or 30 Then to find the ascensional difference is of greater importance than would be at first supposed, as it is a kind of stem from which several important particulars branch out. The next subject in order is on the climates. The Cheng organ has air-chambers which are veritable pipes in form as well as function, for they are tubes formed of reeds: so it is a reed instrument in both senses; probably it is the father of that branch of the family which has been known in Western Europe for fally half a century. I have read that it was copied and adapted by an organ-builder at St. Petersburg long ago. Very likely it suggested the arrangement of parts patented by Day in 1829, in which each reed is enclosed in a separate rectangular pipe. In my oldest eolophon, constructed under this patent, the reeds are placed on the sound-board in two rows, which affords space for pipes lin. wide, and of any required dimensions from back to front. I may add its steel reeds, of unusually wide scale, are all forged out of thick material, so that they may not jar against their frames. I do not think any one in England combined reeds with pipes in this manner before 1829; but in 1844 Wheatstone carried out the same principle by placing a stopped pipe, with a movable piston for tuning, above the reed, leaving a space of about fin, between them open to the atmosphere. Mr. Hermann Smith, in the introduction to his treatise on the harmonium, gives Debain the credit of the general arrangement of its parts which distinguishes it from the seraphine. Of course the employment of separate air-channels was then by no means new. The merit of Debain was in designing a simple and cheap method of forming the separate air-channels; but, like most so-called cheap things, if not exactly nasty, it is not so nice as a separate pipe for each reed. Debain's pan occupies but little room and greatly improves the tone of the reed used à la seraphine; but we can hardly expect an air-channel Jin. or 4in. long to do this to the game extent as a pipe whose length is 3ft. or 4ft. If any of my readers have had the supreme felicity of hearing the sweet sound of a common organ bass beating reed without its pipe, and afterwards heard them together, I think their doubts of the ameliorating influence of the latter-supposing they ever had doubts --would be solved. Now, of course, I am not going to say that the noise and impurity of the sound of the worst of free reeds is anything like the row made by a large beating reed, but it is quite bad enough in all conscience when, like our first parents, it is quite naked. In both cases clothing is a prime necessity for anything approximating to decent effect, but on the same principle that an instrument whose tone is so coarse that it would be unbearable in solo parts, becomes endurable in the orchestra; so also the sound of our naked free reed (perhaps sometimes more free than welcome) when heard in combination with the tone of a pipe, which, according to Hermann Smith, is just what the wind channel of the harmonium is, becomes not merely endurable, but, when that channel is well proportioned, very pleasing. Besides sweetening the harsh sounds of the reed by mixing them with the dulcet tones of the pipe, the reed itself may, by altering the proportions of its length to its width, and yet more by reducing the weight of wind, be made to utter comparatively pleasing sounds. Any one who has an harmonium, seraphine, or concertina may readily demonstrate this latter fact by blowing very gently. Much may also be done by good workmanship, perhaps also by choice of material, although I for one have not a very lively faith in the alleged great influence of material on the timbre of reeds. Mr. Jones complains that all the harmonium class are slow of speech. Now this is sometimes an advantage to ourselves, if not to musical instruments. Had he been rather more so before he condemned the whole class, and then claimed for one member of that class, viz., the so-called reed-organ, freedom from that very fault, it might have been preferable for him. That a free reed is not necessarily slow of speech the quick speaking of the free reeds in the American organs should have convinced him, if further evidence of a fact which has long been notorious was wanting. Νο doubt the old seraphines usually spoke but slowly, but quick or slow, speaking is in the absence of any mechanical means of compelling the reed to vibratesimply a question of the relation of the pressure of the wind to the stiffness of the reed. Weak reeds speak quickly with light wind, and much stiffer reeds than those used in harmoniums of ordinary construction may be made to speak quickly by proportionate increase in the pressure of the wind. It is just the old workshop saying over again, "It's no nse trying to drive tenpenny nails with fourpenny hammers." When we want to succeed in this life we must do as the Prussians are doing now-in their works of charity and mercy on the French, "see how these CHRISTIANS love each other"-in a word, we must use the means appointed if we are to succeed. To some extent the means appointed were used even in the old despised seraphine, yet more in its first cousin (the breed was at its birth greatly improved) the eolophon. I have repeatedly heard the late Mr. Warne play Mozart's overture to "Figaro" on this instrument in less than 3m., not quite fast enough for Costa and the Opera, but not so slow as I have known a good organist, not to mention lady pianists. A much better founded complaint is, that in all ordinary free reed instruments the bass overpowers the melody; the "perfect cure" has, I fear, yet to be found. Perhaps, if the treble reeds were connected with comparatively long pipes, increased in width, and blown by heavier wind, this evil might be much diminished. In the latter case two ranks of keys would be necessary-i.c., a separate rank for the melody-but then no organ (pipe or reed) can be worth much, in the musical sense, with less than two ranks of keys. As we have resorted to duplicating the unisons in the treble of very large organs, there can be little objec- several layers of what I once took the liberty of calling tion to doing the same thing in reed instruments; in-bed-clothes, each layer of which might be gradually deed, the thing is commonly done, and greatly im- lifted by a swell pedal (which would then well de proves the treble in power. serve that title) in succession. I think it will be ad mitted this would be as nearly the perfection of a pedal swell as it has entered into the heart, or rather into the brain, of man to conceive; but I again say that I much prefer to do the "expression business" with the fingers, probably because long practice has rendered it easy to me. THE HARMONIOUS BLACKSMITH. It is the fashion nowadays to sneer down the employment of mechanical means (other than air pressure) to compel the instantaneous vibration of free reeds. De gustibus, dc. I rather like some of the effects of plectra or hammers on reeds; perhaps this may be due to my unrefined taste, or total want of taste. The application of percussion to musical strings, when performing the function of reeds in addition to their ordinary function, was patented by Wheatstone some years ago, and of plectra to free reeds at the same date. Hammers were applied to reeds by Hewett, 1844. (Qy. did Kaufman anticipate this?) Mr. Jones's illustration (which, by the way, throws no light whatever on the relation of reeds to air-chambers) of the violin string stretched over a thick plank of wood is singularly unfortunate; so long as the plank be very thick in proportion to the weight of the string, very little tone can be got (it is the fourpenny hammer driving the tenpenny nail again). Nor will making the thick plank into the top of a box much mend the matter, far less produce an Amati. We must either augment the weight of the string until it is heavy enough to move the plank, which then becomes a sounding-board proper, or reduce the thickness of the plank until an ordinary fiddle-string can move it. As regards the loudness of the sound produced by a sounding-board striking the air, but little difference is observable, whether that sounding-board forms the top of a box, or is exposed to the air on both its sides; the air in this box-i.e., violin-probably does more or less influence the timbre, but its action in the way of increasing the loudness of the sound, is to me inappreciable. Nor can we, on reflection, expect that it should augment loudness, for the back of a fiddle can hardly cause its belly to strike the air more forcibly, which is the one thing needful for increase of loudness. If it be said the back forms a second belly, and thereby duplicates the area of soundboard: I reply, quite true; but as in the violin the back of the upper belly and the top of the bottom belly-i.e., the back-are enclosed by the sides, it follows that any advantage which might result from doubling the area of sound-board must be nearly lost. It would be quite lost but for the existence of the so-called sound holes. From the experiment Mr. Jones suggests, I fancy he has hardly realized the true function of a musical string. Its sounds are not (like those of a gong or bell) due to its striking the air, but rather to its causing the table de harmonie, or soundboard, to do so. Its function, in relation to the soundboard is very analogons to that of the reed mouth of an organ pipe, i.c., it compels the motion of a much larger body than itself, the reed causes the air in the pipe to move and become resonant, the string acts like a drumstick and strikes the soundboard, putting it into vibration, and the soundboard in its turn strikes the air. Very little sound is perceivable when a string is stretched over a metal bar or even over a thick wooden block, and but little sound can be heard if a free reed be vibrated when its frame is fixed on metal which does not act as a soundboard to any sensible extent, and no current of air is passing the aperture it closes; in both instances because the surfaces of the vibrating body are small. [407] SIR,-Reading with interest all that has been written by Mr. Eustace Hinton Jones and other correspondents on the American organ, I find it expedient to notice an instance of misrepresentation of my words, and gently to remonstrate against the evident tendency to misapprehend the bearing which my unreserved exposure of the defects of harmoniums has upon the present controversy. Very possibly readers who are not writers may be similarly influenced, inclined to draw unfavourable conclusions, and to take sides with the reigning rival of the hour, whose beauties are landed by a chorus of admirers-a rival that as yet has had no faithful expositor to lay bare its constitution and dis course of the ills it is heir to. Mr. E. H. Jones in his last letter (381, page 614) has not quite accurately represented my statement, indeed he makes my words bear an interpretation the very reverse of that which my reasoning sought to establish. Quoting from my last chapter he, in parentheses, attributes to me a saying which on reference he will perceive the paragraph does not imply. Here is his excerpt:-"No doubt a smoother bass would be gained and better balance of tone (that is, were reeds employed of such a size as would necessitate a case almost as large an organ), for at present the tenor and bass are shorn of their just proportions, in order to economize space, and hence the roughness and reedi ness preponderates, drowning the treble, nnless great skill is exercised to restrain it within due bounds." My argument was not for larger reeds, but for longer channels, as the natural remedy for a too great preponderance of the strength of the bass reed-the reed of the proportions ordinarily in use. The construction of the harmoniam could of course be changed to admit of a fuller proportion of channel-my purpose has been to describe the harmonium as it is in the average, not to plan new models; but in exposing defects I have always intimated the path in which the true remedy is to be sought, and have expressed my content with and enjoyment of the qualities which are possible to and have been attained in the harmonium, believing in fact that the future scientific development of the capabilities of the instrument will render the harmonium more and more worthy to be accepted as the legitimate representative of the organ. The skill I refer to as requisite to restrain the power of the bass within due bounds relates to the manufac turer not to the player, a skill in preparing the reed properly to consort with the channel, and which it has been my anxiety to impress upon all amateur artists carefully to cultivate as they value quality of tone. I entirely acquit Mr. E. H. Jones of any intentional misrepresentation; it is an inadvertence which might happen to any of us when mentally pre-occupied and engrossed with our wishes. HERMANN SMITH. I have already said that we sweeten the harsh tone of the free reed by mixing it with the pure tone of the pipe. Now it is the common fault of most harmoniums that we have too much reed-tone and too little pipeHARMONIUMS AND HARMONIUM PLAYING. tone. The obvious remedy seems to be to augment the length of the column of air in the wind channel or pipe; [408] SIR,-There is such an amount of truth and and when Mr. H. Smith wrote that the arrangement of good sense in the letter from R. H. Nash (311) that I the parts which cause the sounds of the harmonium feel constrained to endorse it and to add a few remarks. was by no means the best arrangement conceivable, II fully agree with the writer when he says that Mr. E. suspect he had this idea in his mind. Why the pipes H. Jones (239) knows but very little about haror wind channels are not made longer and wider in the moniums, their capabilities, or their use. In the rebass is, I strongly suspect, rather a question of commarks I am about to make I will be as brief as possible, mercial convenience and profit than one of science. In knowing the value of your space. I think, however, a tall case, like that of my eolophon or that of the Ameri- that the subject is one of considerable interest, as well can reed-organ, long air channels or long pipes can be as of practical importance. used, i.e., there is height enough for them (Qy. do the makers of this instrument avail themselves thereof); but we must remember the longer we make the pipes the further we depart from the ordinary proportions of the harmonium, and the nearer we approximate to ranks of organ pipes with reed mouths. most I understand the mechanical swell of the American reed-organ is very good. Well it may be, for it has room for every facility required to obtain a good swell. In reed instruments there are two methods-which may be combined-of obtaining a swell. The ready, and perhaps the most effective, is to increase the pressure of the wind, and this is just what we do with the concertina, with Erard's orgue expressif, and with the harmoninm, when using the expression stop. The other method is that nsed in the seraphines and in organs; we shut up the sounding body in a box, and, by gradually opening the box, "let out the tone." I much prefer the first method for rendering melody with true vocal expression; but it is a difficult thing to do well with the feet, unless indeed what Mr. H. Smith terms "foot touch" be very highly cultivated, and kept in constant practice. When carried out à la main, I find it, probably from long experience, very much easier; but this method the modern race of harmonium makers, for reasons best known to themselves, fight very shy of: perhaps it don't pay commercially. That kind of swell which is to be got by smothering the t one and gradually letting it out might be obtained in a free reed instrument to perfection. Not to mention the "swell within a swell" advocated so justly by "Adept," the remainder of whose most practical and instructive communications we are all longing for, we might use First as regards the so-called American organ, I have been at the trouble of examining them very thoroughly, and of obtaining one for my own use. There is very little difference between them and a really good English harmonium. I do not now allude to Alexandre's instruments; they are so infinitely inferior to English instruments, as regards tone, that we will only take a passing notice of them, I am utterly astonished that the musical profession persistently adhere to them. One reason why they flood the country is perhaps the enormous discount the manufacturers and their agents allow to the retail sellers (often equal to 30 per cent.) On this account buyers can scarcely expect to get their money's worth for the price they pay. But take a first class instrument by Evans, Ward, Hermann Smith, or Kelley, and its capacities are unlimited. Ward's seem to have as great purity and beauty of tone as any I know, and one of his twenty-five guinea instruments is equal in power to an eighty guinea Hamlin organ. Upon one of these English instruments almost anything can be played. Scarcely any musical instrument cannot be imitated, and with a little taste the most exquisite accompaniments can be played to ordinary psalmody. But it will not do to have the common style of playing on the harmonium. I know a magnificent organ player who plays on the harmonium so badly that he drives the people away from the church where he performs. With your permission I propose to forward a paper or two on harmonium playing, for the benefit of your general readers. I have myself given a recital on a ten-stop Ward's harmonium, which, for two hours continuously, has delighted an attentive audience. A few simple rules and a little tact are all that any sensible person would require. Briefly then to corroborate Mr. Nash's remarks. If Mr. Nash had taken an English harmonium of a good maker, instead of a 13 stop Alexandre, he would have been as sanguine as I am myself. The harmonium is not necessarily reedy. Common instruments undoubtedly are, but their faults may be disguised by good playing. The bass only overpowers the treble when the performers will play chords in the bass, and play from music in which the tenor part is arranged in close proximity to the bass. In harmonium playing the tenor should almost always be played with the right hand, it is sometimes necessary that it should be played higher than written. The intonation of the harmonium is not sluggish, unless the reeds are shamefully bad. I cannot, however, agree with Mr. Nash as to the value of the American organ. The price is enormously out of proportion. This is caused partly by the cost of carriage from America, but also by the difference in the value of gold. One of your correspondents, a short time ago, stated that he was having a very superior instrument made with a large number of stops, I should like to know the maker of the instrument he so much admires. CLEFOR CARDIFF. VINE GROWING. [409] SIR,-I think I can give your correspondent "In Vino Veritas" a simple and easy plan for pruning his old vine. Having had an old vine myself, which a few years ago produced bunches rarely over 3oz. or 4oz. in weight, and being ignorant of the treatment required, I, like him, began to make inquiries, the result is that I now get grapes of an excellent quality, many branches being lb. and some lb. in weight, the vine being an ordinary white grape. The secret is contained in two words-"new wood." The reason "In Vino Veritas" has some fine bunches on his north wall is because his young wood is there. I will venture to say that the other part of his vine consists of old branches. Presuming that his vine consists of the usual main horizontal with perpendicular rods, the way to proceed this subject I would just remark that in the "Lunar be; but still it will be delightful to have pointed out to BICYCLE RIDING. [411] SIR,-Your correspondent Henry W. Reveley his figures of the number of revolutions per minute re- hour, but I think his argument does not hold good as goes MATHEMATICAL INSTRUMENTS. [415] SIR,-In reply to "S. H." (p. 619), the joints of drawing instruments are hard soldered on. This is done by means of spelter or silver solder over a charcoal fire, using powdered borax as a flux, and removing the article from the fire the moment the solder is observed to "run." I should say that an amateur would find it better perhaps to soft solder them together by the usual tinman's solder, using chloride of zinc as a flux. This would be found quite strong enough for all ordinary purposes, and much less trouble to inexperienced hands These instruments are finished by the makers upon a leather wheel like a scissor-grinder's lap, with a little fine emery or pumice-stone and oil. Some makers ing the instrument in the left hand upon a piece of finish their best instruments by hand in the vice, holdcork (a large bung will do) and polishing across, first, with pieces of fine emery paper wrapped round a small smooth file held in the right hand; and, finally, by means of a buff-i.c., a piece of hard wood about sin. long, with a strip of thick buckskin leather glued to one side, and sprinkled with emery, rotten-stone, or brickdust. Further information if required. E. M. TYDEMAN, Practical Optician, Brighton. MICRO-FUNGL in my papers on the microscope I shall take occasion mean time the best season for their collection is passing away. The thought has, under these circumstances, suggested itself that a specimen of micro-fungus in situ would be a great help to a would-be collector, and I will willingly send to any reader who cares to send me a stamped addressed envelope a specimen of some com I can spare from business-are very numerous. [416] SIR,-Some correspondents of mine have expressed their inability to discover these interesting is as follows:-Wherever he has a vigorous young shoot objects. I believe this is entirely owing to their not of sufficient length let him nail it in to take the place to its being kept up for any length of time. He seems knowing what to look for, as these objects themselves of an old branch, which must be cut away (in November), to assume that great power is required to propel the are this year at least sufficiently numerous. Later on no branches being nearer together than 18in. This allows sufficient room for the ripening of both fruit and vehicle, and that there is no down hill on the journey; to speak of Fungi and their collection, but in the young wood. Say he starts pruning in spring-when the laterals are of sufficient length to be pruned-that is, when the young grapes have set-let him pinch off the shoot at the second joint from the bunch; all shoots on the main stem being pinched out except the requisite number for next year's crop, which should be trained up between the bearing branches. The vine will want looking over in about 4 or 5 weeks after the first pruning, when the fruit-bearing branches will have made a leading shoot, which must be pinched off, leaving one joint. Perhaps it may require looking over a third time in the same way; then in November let him cut away the rod which has borne fruit and he will have a set of new rods for next summer's crop. If he follows this plan, called the long rod system, he will never again complain of his old vine being unfruitful. As to his second question, of how to proceed to grow vines for a wall, I cannot recommend a better plan than Saunders' plan of planting vines 2ft. apart and pruning on the spur system. He will also see how to make his border. The work is entitled "A Practical Treatise on the Culture of the Vine," by John Sanders, London: Reeve & Co., 5, Henrietta-street, Coventgarden. Either black or white grapes do well if the proper sorts are planted. Of the white, the Grove End sweetwater is as good as any, and of the black, the Esperone-both produce large bunches, of good flavour. A NEW SUBSCRIBER. LUNAR ATMOSPHERE. [410] SIR,-Could not the vexed question of the moon's atmosphere be settled by means of a welldevised and carefully executed series of observations? We have it in our power to compute the time of sun rising at any particular spot on moon's surface, and we also possess the means of observing, in some instances at least, its exact moment, when, for example, the shadow of an isolated peak (as Pico) is just discernible on, or emerges out of, the darkness covering the plain to the east of it. True it is that the opportunities for such an observation occur but seldom in any particular case, nevertheless, when they do occur, and are seized for the object in view, a number of them may go far to throw some light on this obscure question. It is only at the lunar equinoxes when the moon. = 0 or 180° that the terminators coincide with two of the lunar meridians; at all other times they form greater or less angles with the meridian, varying from 1° 32' 9" in one direction with 90 to the same angle on the other side = 270°, and these angles are equal to the sun's declination, as seen from As the computation of sun rising and setting at any given point of the moon's surface depends on the mean period of rotation of the moon, and the inclination of her axis, the time of observation of sunrise or sunset is of course equivalent to apparent lunar time to be corrected by an interval of precisely a similar nature to our equation of time. If, therefore, both mean and apparent lunar time are rigidly computed, and the times of observation precisely agree with them, the evidence of the absence of an atmosphere is very strong. We know, however, that refraction accelerates sunrising and retards sunsetting, and if there be a sensible difference between the computed and observed times it will go far to establish the existence of an atmosphere. Spots in high latitudes are most suitable for this purpose. In connection with TO MILLERS. I think we could scarcely go that distance in any part for a walk. BICYCLE STEP. [413] SIR,-I should like to add a few more par- JOHN C. FRANK. THE PHANTOM WHEEL. [417] SIR,-I have been surprised to see several important questions on milling remain for some time unanswered; such should not be the case. In answer to the question, what length of reel is required to dress from six pairs of millstones :-A reel, three feet in diameter, and from 24 to 32ft. long, with a suitable cloth would probably answer on dry foreign wheat, while double that length of reels would not give satis faction on English wheat after a damp harvest. After many years of experience, I should not recommend silk in a country mill on English wheat, as you cannot alter the cloth to suit the seasons. Just before harvest I was dressing all my flour through a No. 16 Blackmore cloth, and as it was hardly fine enough, I frequently dressed the flour over a second time. Since the new wheat came in I have dressed all of them through a No. 12,with perfect satisfaction to myself and my customers. With silk, you can neither regulate the feed nor the No. of the cloth to suit the meal you are dressing. If I were now about altering a mill, or building a new one, I would put up four bolters, with a No. 8 cloth on the first reel to remove the coarse offal, and receive the heads into a No. 10 cloth to remove the coarse sharps, on the next reel a No. 12 to remove the fine sharps, and on the last reel whatever cloth was required, from a No. 12 to a No. 17, and I believe the dressing would be as perfect as it is possible to be made in a country mill on English wheat. It would be but little trouble for some of our milling friends to dress a score of meal down on this plan, and state the result in the columns of the ENGLISH MECHANIC. Of course the above remarks are open to criticism. I would also notice another question-a miller has a sixteen feet overshot wheel, and can obtain from 4ft. to 6ft. more fall; I believe it is not possible to utilize it except by putting in a N. N. SMITH. larger wheel. ENGLISH MECHANIC MICROSCOPICAL [118] SI,-Probably something good may be made out of this suggestion if the readers of this journal take it up with a will. I don't think my friend, "A. A. F." wishes to interfere in any way with existing societies. If I understand his suggestion rightly, he wishes to originate a microscopical observing society, similar in many respects to that formed by our astronomical friends, but with this advantage over them, that "A. A. F." proposes to exchange or circulate specimens of the objects observed. If the idea should gain ground and be pronounced feasible, nothing would be of greater pleasure to me than to give it a push with as much power and discretion as possible |