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with nearly all the fine chemicals. As a result of allowing these trades to pass so much out of our hands, we are faced with the position that stocks are rapidly diminishing and prices are rising to such an extent as seriously to hamper many of our industries.
The great dyeing industry has been lost to this country because we, as a nation, and our manufacturers in particular have failed to understand the extreme complexity of the scientific basis of organic chemical industry. Science has been neglected in the works, and the chemists trained in organic chemistry necessary to carry on the industry in successful competition with Germany were not to be found in our universities. In 1870, the time when this industry commenced to be transferred to Germany, organic chemistry was not recognised by our older universities, and the newer universities, which since then have done so much for the progress of science, did not exist. Many of our universities, and particularly those of Oxford and Cambridge and those in Scotland, contributed practically nothing to the advancement of organic chemistry in the latter part of last century, and even now their output of research is far less than it should be; while in Germany, as soon as the importance of the subject became apparent, schools especially devoted to the subject were founded by such great teachers as Liebig, Wöhler, Kekulé, and Baeyer. Every effort was made by the establishment of laboratories, aided by the State, to help forward the new movement, and the step which assisted more than anything else was the provision that in every German university, research must be an essential part in the training of every student of chemistry, who, in order to obtain his degree of Ph.D., spends at least one and generally two years in research; whilst in this country, students obtain their B.Sc. honours degree after a course of three years' study, and the majority are under no obligation to do any original research during their university career.
The recognition of the necessity for research forming an essential part of the training of the student in science has been responsible for the large output of original work in Germany as compared with this country. The B.Sc. degree, and certainly the B.Sc. honours, should not be conferred except on those who have undergone a course of research work, and the necessity for a change in this direction is now being recognised, though the proportion of graduates who engage in research in these circumstances is small compared with the number of Germans who qualify for the Ph.D. degree. Had there been a supply of firstrate chemists at the disposal of the manufacturers of this country there can be no doubt that such industries as the aniline dye industry and the coal tar industry would still be in existence and flourishing here.
Germany has recognised the value of the closest possible contact between the industries and universities, and the majority of the professors and privatdocenten keep in touch with the large factories. Appreciation by the manufacturers of the value of science in connection with industry is one of the reasons for the development of the German chemical works. To obtain a share of the wealth and prosperity opened by this vast industry, our manufacturer must so conduct his works that research is going on unceasingly; his laboratories must be properly equipped and staffed by research chemists of ability, with a scientific leader to direct the work; for the first essential for the success of a chemical works is for it to be under chemical control, and every department must be in the hands of an expert. Recognition of the soundness of this principle is one of the main reasons for the success of the works in Germany, where all the principal dye works are under chemical
control; chemists are the heads of departments, and are included in a large proportion on the board of management.
In order to deal with the problem of the shortage of dyes in this country, schemes have been proposed by the Government to ascertain the best means of obtaining sufficient supplies of chemical products. The first scheme recommended by the special committee appointed by the Government was not cordially received, and in explanation of this it should be pointed out that the committee consisted entirely of business men. Had a chemical expert been present, such a scheme would not have been placed before the public. In the memorandum of agreement it is stated that the company has been incorporated for the purpose, amongst other things, of manufacturing and selling dyes, colours, and other chemical substances which, previous to the war, were exclusively or principally manufactured in Germany, and no mention is made of the main object of such a company-namely, the employment of a large staff of research chemists under leaders of ability for the purpose of making discoveries in every possible direction.
It is not merely a question of producing the dyes that are required during the war; the company must be able to compete successfully with the German industries after the war. No greater mistake could be made than to think that in order to manufacture a dye it is only necessary to follow the directions given in the patent, for the patent is so worded that while it satisfies the requirements of the patent laws of the countries in which it is taken out, it gives as little information as possible, and contains no indication of the process used in the actual manufacture. In the first place the methods of manufacture and the utilisation of by-products must be worked out until they have arrived at the same state of efficiency as in Germany. Another point to be borne in mind is that the Germans supply dyes to practically all the other nations, and could well afford to sell dyes at a loss to themselves in this country until the English company had been ruined. And what will happen after the war with regard to using German patents? Will these patents again become the sole property of the Germans and be workable in this country only on the payment of royalties or licenses?
The application for shares in the proposed company was unsatisfactory. The Government withdrew the first scheme and substituted an amended proposal which is a proof of a desire to meet in a generous spirit the criticisms raised against the first scheme. The grant of 100,000l. which the Government proposed to make to the company for research purposes would be better employed in subsidising the research laboratories of those universities and colleges willing to specialise in organic chemistry and to train a certain number of students with a view of their entering the service of the company.
The existing dye works in this country compare very unfavourably with those in Germany, where experience has been in favour of building large works and against spreading manufacturing operations over small works situated in different parts of the country. Moreover, in the manufacture of any substance byproducts result, which must either be recovered or used in the manufacture of other saleable products, and in order that these by-products may be used to the best advantage, the dove-tailing operations should be carried out on the same site, and thus save transporting the by-products from one works to another, an operation that must entail loss. The proposal of the Government, therefore, to take over the existing works in this country appears a doubtful policy.
The German works with which the new British
company must compete are enormous organisations controlling almost unlimited resources, and if after the war these organisations continue to work with the same efficiency as before, some years must elapse before we could compete successfully with them. Failure to develop on research lines is scarcely conceivable if the works are in the hands of a highly trained chemical staff; but if the new industries get into the power of the business man who wants an immediate return for his outlay and fails to appreciate the vital importance of scientific control, then no protection by a tariff on the import of German dyes and other organic products can avert disaster.
THE CO-OPERATION OF SCIENCE
Mr. Taylor Peddie, chairman of the Institute, stated that the Institute aimed at embracing within its membership the trade organisations of the country, and that already much progress had been made in this direction and with the formation of a trade bank. Prominent men of science had joined the court of directors of the Institute, and by development of this scheme it was hoped to bring science into intimate contact with industry. Mr. Peddie then opened the discussion by reading a paper upon "The Influence of Science upon Political Economy," in the course of which he demonstrated from comparative statistics the large reductions in the cost of production that had been brought about by the application of science to processes of manufacture.
Sir Philip Magnus stated that the output of research work from the English universities was equal to that of Germany, and that their graduates were as capable and as well trained as those from the German universities; but that, owing to our lack of appreciation of science, we made practically no use of our research work, nor of our trained men. He felt that any movement trying to bring about a more marked sympathy between science and industry was worthy of the greatest support.
The Earl of Portsmouth, in moving a resolution to the effect that the meeting supported the organisation of capital for industrial purposes, and that it agreed that a closer co-operation of science and industry was essential, stated that he was of opinion that in the near future the people now drawing their income from land and property would by force of circumstances be compelled to turn their attention to industrial affairs.
The Hon. F. Mackenzie (Agent-General for New Zealand), in seconding the resolution, expressed the opinion that we were too prosperous in this country to appreciate the need for organisation. He stated that twenty-five years ago agriculture in New Zealand was at a very low ebb, farmers were selling sheep at the rate of 18s. 9d. a gross, butter was 4d. a lb., but now, through careful organisation and the application of science to agriculture, New Zealand was a prosperous country, exporting a considerable amount of produce to England. S. R. I.
THE HE spring meetings of the Institution of Naval Architects opened on Wednesday, March 24. Owing to the war, the meetings were curtailed somewhat; eleven papers were read and discussed at morning and afternoon meetings on Wednesday and Thursday. The Marquis of Bristol was re-elected president for the ensuing year, and in his opening address made reference to Germany's methods of submarine war. He suggested that; in order to obtain reasonable protection from submarine attack, it might be advisable to arm all merchant vessels to an extent which would render them dangerous to submarines.
Prof. J. J. Welch's paper on the watertight subdivision of ships was limited to a discussion of the orderly subdivision of ships, particularly as effected by transverse watertight bulkheads. The paper included a historical sketch leading up to the work of the bulkhead committee of 1912. One of the difficulties which had to be faced by this committee was the question of permeability. The same ship, whilst loaded to the same water-line, might carry cargo of very different density, so that with the same arrangement of bulkheads different standards of safety would obtain on the two voyages. Ultimately the conclusion was reached that a fair average permeability for cargo spaces was 60 per cent. Spaces devoted to passengers are taken at 95 per cent. permeability, and machinery spaces at 80 per cent. The paper goes on to discuss the recommendations of the bulkhead committee's report on oversea passenger vessels, and the author considers that the proposals in the report represent a very decided step forward.
An interesting paper on the influence of discharging appliances on the design of large ore carriers was read by Mr. John Reid. The shipment of ore on the Lakes Superior and Erie route has reached in one year the enormous total of nearly 50,000,000 tons. The author gives a description of the Hulett unloading machine, an appliance which has enabled a cargo of 10,000 tons of ore to be unloaded on the Great Lakes in less than three hours. Unloading and loading machinery of this description has led to the design of ore-carrying steamers in which the greater part of the length of the vessel is taken up with cargo holds, and practically the whole deck is covered with hatches. The rapid loading of such vessels is apt to produce great strains; a speaker in the discussion instanced a case of one of these vessels acquiring a deflection of 11 in. during loading. The author of the paper directed attention to the backward state of the facilities in Great Britain for handling and transporting ore, and showed how some of the leading features of the Great Lake ore-carriers may be adapted with advantage for ocean-going ore-carriers.
Mr. J. Montgomerie read a paper on the scantlings of light superstructures, by which is meant the light steel deckhouse erections now commonly fitted above the strength deck in passenger steamers. Two alternatives present themselves to the designer :—(1) The structure may be made so flexible that it cannot take any share in the straining action to which the vessel is exposed as a whole; (2) it may be made strong and rigid enough to share that general straining action without damage. The first method of design is impracticable, since the superstructures have to carry heavy weights such as boats, casings, and funnels, and the structure has to be substantial enough to support these when the ship is moving in a seaway. Partial flexibility may be obtained by cutting the superstructure at several places and fitting expansion joints. The whole efficiency of such joints, in respect of the relief from stress which they afford to a long house,
depends on the distance between them, and that in turn states a problem in shipbuilding which has never been solved satisfactorily, viz., the determination of the distribution of stress in way of an abrupt discontinuity, such as a bridge, or other erection. In the absence of any theory to which complete assent can be given, we must turn to the record of experience. The author then proceeds to give descriptions and illustrative sketches showing typical cases of damage to existing ships at places of discontinuity. These examples are of particular value to engineers and others interested in the strength of materials, and will well repay careful study.
An analysis of the damage observed supports certain conclusions which can be drawn from a consideration of the whole question of superstructures :-(1) That in way of a discontinuity in the structure of a ship, stresses outside the erection will be transmitted to the material of the deeper girder much more rapidly than has been thought to be the case; (2) that the fitting of expansion joints, spaced as in the present practice, does not appreciably relieve the superstructures of stress, or obviate damage; (3) the best method of providing against damage in deckhouse superstructures is to dispose the material so as to make these capable of taking part in the straining action of the hull, following as far as possible the general law that all discontinuity of longitudinal material should be minimised. The author then proceeds to take certain typical cases, and gives methods of working out the scantlings required to comply with (3), above noted.
Mr. F. W. Lanchester gave a contribution to the theory of propulsion and the screw propeller. The author made reference to the controversy in which Dr. Froude's work was attacked violently by Prof. Henderson. Without entering, or taking part, in the dispute, Mr. Lanchester reviews the theory from its foundation, in order to make sure of his own ground. In the past there appears to have been insufficient attention to the initial definition of the problem, with corresponding uncertainty as to the ultimate interpretation of results. In discussing Dr. Froude's theory, and speaking academically, Mr. Lanchester says that the weak point of the whole conception is that there is no proof offered that either the work done (i.e. the energy expended), or the momentum communicated, is confined strictly to the column of fluid passing through the actuator, and there is, in fact, nothing to restrict, or confine, the fluid as in the case of the efflux theory, by which the problem is rendered really definite. It is understood that the régime contemplated by Dr. Froude is not capable of exact expression. This, however, is no obstacle to the application of any theory in real hydrodynamics; if it were necessary for the engineer to await the work of the pure mathematician in these matters, the subject would have made scarcely perceptible progress since the time of Noah. In such a case as the present, if the method of treatment contains 80 or 90 per cent. of truth, it may demand acceptance.
Further work at the William Froude National Tank on the resistance of mercantile ship forms was presented by Mr. J. L. Kent, and Mr. Stromeyer contributed an interesting paper on the law of fatigue applied to crankshaft failures.
modern gun, and the high pressure still remaining when the shot reaches the muzzle, make the conditions more serious than they used to be comparatively recently. Not only those who are near the gun when fired, but those also in the neighbourhood of bursting shells, bombs, or explosives, are liable to suffer in a similar way even if they are not otherwise damaged.
Mr. A. Mallock, F.R.S., who has for many years conducted investigations in connection with artillery, has invented an ear defender," the object of which is to protect the drum of the ear from very sudden and violent access of pressure, while still allowing the minute variations produced by ordinary sounds to be received with but little loss. The defender consists of a containing piece made of ebonite and shaped like the pieces used in the game of Halma, and of about the same size. The ball end is very finely milled, and it is made to fit the passage of the ear, there being five sizes, differing very slightly in size in this part, to suit different people. The piece is pierced centrally by a hole 5 mm. in diameter at the small end, and gradually enlarging towards the other end, where it opens into a recess 1 cm. in diameter. Into this are fitted in order a flat ring washer, a disc of fine wire gauze, a very thin, flat ring washer, a delicate diaphragm, a very thin, flat ring washer, a disc of fine wire gauze, and a flat ring washer. When a pair of defenders are placed in the ears, the thin diaphragms, untouched except near their edges,
where they are held, are free to take up aerial vibration and to transmit it to the ear passage, and so the wearer hears ordinary sounds with but little loss; when, however, the violent impact due to gun fire or explosion in the neighbourhood occurs, the diaphragm. is brought up against the wire gauze, by which it is prevented from further movement, thus limiting the increase of pressure in the air passage and defending the ear.
The defenders are neatly packed in a small tin matchbox with a rubber fitting, which prevents them from falling out, but which allows them to be removed at once. A small cleaning tool is similarly held elastically so that it cannot fall out by accident. The price of the set is three shillings, and at the present time there is great scope for its use. The instrument is called the Mallock-Armstrong ear defender, and the address of the proprietors is 86 York Street, Westminster. C. V. B.
SOME SCIENTIFIC ASPECTS OF
HERE are few modern inventions which have not been employed in the present war for the destruction of property and of human life. The pneumatic piano-player is an exception. It is also exceptional in that it possesses but a scanty literature outside the catalogues of the manufacturers. It has never been associated with any inventor of distinction, and the general public knows nothing about its history. The aeroplane, on the other hand, is closely linked in popular thought, not only with such modern names as Wright, Langley, and Blériot, but also with the names of early designers and projectors of flying machines, such as Dante of Perugia and Leonardo da Vinci. Yet, considered merely from an engineering point of view, the modern piano-player is a marvel of human ingenuity.
The feature which distinguishes it from its early predecessors is the element of controllability, which leaves the interpretation of the music largely to the
1 Abridged from a discourse delivered at the Royal Institution on Friday, March 19, by Prof. G. H. Bryan, F.R.S.
choice of the performer. Of recent years, however, personal control has been supplemented by accent devices, automatically operated, the construction of which is essentially an engineering problem. The separation of the scale into two independently controlled halves was certainly to be found in the old mechanical pianotist in 1902, and it may date from still earlier. I consider this last feature unnecessary, and its use open to serious objections.
The object of my experiments has been to apply dynamical and physical principles to the control of what I will call the striking action in piano-players, as it very soon appeared to me probable that by so doing it would be possible to obtain differences of effect that could not be produced by purely mechanical methods.
The ordinary practical man asserts that in striking a note or chord on the piano you can increase or decrease the force of the blow, but that the only effect will be to play the whole chord louder or softer, so that you cannot bring the bass or treble parts into prominence unless you connect the pneumatics with different degrees of vacuum. I have been told that it is mathematically impossible to produce effects without which I now regard no piano-player as worth playing.
But any mathematical physicist will understand that what engineers call the "force of the blow" is in reality a very complex phenomenon. In my piano I find that a fairly soft note is produced in the middle of the scale when the hammer strikes the strings with a velocity of 30 cm. per second, and that the hammers themselves rise through a height of about 5 cm. This means that if the acceleration were uniform the operation of depressing the key and releasing the hammer would occupy one-third of a second. But during the operation the pressure applied to the key may be in-. creased or decreased in an infinite number of ways. It may be made very large at the commencement of the blow, sinking to zero at the end, as when a fingerpianist strikes the note from a height; or it may be very small at first and gradually increased, an action which some describe as a "caressing" touch. These differences would be represented by differences in the shape of the graph connecting the pressure on the key with the time measured from the instant it is first touched to the instant that the note is sounded. We might call them differences in the "shape of the blow." But the check action greatly influences the character of the accelerating force impressed on the hammer when regarded as a function of the time. The operation of playing a note is usually divided into two periods. At the end of the first period a support is withdrawn from the palet which raises the hammer, and the latter becomes disconnected. In the second period either the hammer may fly up freely and strike the note, or the palet may again overtake it and drive it forwards. To produce these different actions the variable forces applied to the key of a piano must evidently be similar in character to the "screw-back" and "following" strokes in billiards. It is, of course, theoretically possible that the hammer may rebound and strike the string a second time. But it is very difficult to test this point.
Another important point is that, as the driving force is applied close to the base of the hammer, considerable flexural vibrations are liable to be set up in the shaft. These may probably differ in amplitude and phase, according to how the note is struck. A difference in this respect may affect the tone-quality.
Now the bass and treble hammers differ considerably in weight, and therefore also in inertia, and the intermediate hammers vary continuously from one end of the scale to the other. It follows that a short sharp
blow will produce its greatest effect in the higher parts of the scale, while a longer sustained blow, or an increasing blow, will drive the bass notes forward with increased velocity even after the treble notes have been released.
In the case of a repeated treble note with bass accompaniment the second time it is struck, accentuation is more difficult, and there is considerable danger of the note failing to sound owing to the bridge between the two notes buckling, thus continuously admitting air to the primary valves. The best plan is to keep the tension low until the chord containing the repeated note has passed the tracker board, and then force the notes down hard. On account of the additional difficulty thus incurred in reading the music, I believe that it would be justifiable to cut the troublesome note a little after the accompanying chord.
The apparatus originally used in these experiments was figured and described in NATURE of May 8, 1913 (vol. xci., p. 246), but the principle has now been embodied in a patented device which the Moto Music Company, of 42 Eyre Place, Edinburgh, have undertaken to fit to any make of internal or detachable player, and which in the case of a player-piano does not interfere with the appearance of the instrument or its use when required for hand playing. In addition to the suction bellows which generates the vacuum, all pneumatic players have a large reservoir bellows, which acts as an accumulator or condenser of considerable capacity, but between this and the playing pneumatics two channels of communication usually exist. One is through an accent valve controlled by a lever, the other connection is through a smallish regulating bellows, controlled usually by a spring, and through an air valve which opens or closes with it according to the degree of vacuum. This arrangement is sometimes called a "choker," and its statical action tends to equalise the pressure of the air from the playing pneumatics.
Now it will be found that in playing the regulating bellows is in a continual state of vibration, and that this vibration has a very marked effect upon the tone quality and expression. The character of the variable force applied in projecting the pianoforte hammer is determined very largely by the elasticity of the controlling spring, and the fact that this remains constant is found to account for the dulness and want of variety which is noticed even in the best players when they have been in use for a certain time. In my device the spring is replaced by a weight the leverage of which can be varied, thus enabling the tension on the bellows to be varied from time to time in playing different passages, and introducing, further, a variable element of inertia. It is convenient to describe such changes as " sub-permanent." Further, the bellows can be controlled by a hand lever for the purpose of accentuating individual notes, such changes being describable as temporary." The usual expression marks, FF, F, MF, P, and P P, are indicated.
The experiments lead to the following conclusions:(1) A light sub-permanent tension with fairly strong pedalling will give bright treble effects with light bass. A heavy sub-permanent tension with light pedalling produces a strong bass and a soft treble.
(2) Corresponding to every note of the scale, there is an action which produces the maximum effect, this action varying continuously from one end of the scale
to the other.
(3) The brightest effects are obtained by keeping the accent valve open, or partly so, as in this case the closing of the regulating bellows is affected by the pedalling. The effect of closing the accent valve is very similar to the use of the soft pedal.
(4) In playing solo passages, light and heavy sub
- permanent tensions produce different effects even when ! it is sought to maintain the corresponding degree of loudness by suitable variations in the strength and method of pedalling. This observation leads us to believe in the existence of a relation between tonequality and touch. While it is easy for an inexperienced person to produce the necessary differences of touch with a pneumatic player fitted with this controlling device, I find it very difficult to obtain the same effects by striking the keys of an ordinary piano with my fingers.
(5) There appear to be two different ways of accenting particular parts of chords by hand pressure applied to the control lever. With a slight sub-permanent tension, treble notes are usually best accented by depressing the lever before the note has reached the tracker board, and subsequently allowing it to fly up smartly. With a heavy sub-permanent tension, it is necessary to jerk the lever upwards from below just after the note has reached the tracker board. For a bass note with light tension, the lever is firmly pressed down after the note has reached the tracker. With heavy tension the lever is previously raised, and then allowed to drop down with the note. In either case the action is supplemented by a corresponding action in pedalling.
(6) With a heavy sub-permanent tension and the lever supported from below, it is possible to obtain very soft effects in which the treble parts ring out clearly and are not drowned by the bass. With a light sub-permanent tension and the lever pressed down the results are more brilliant. I attribute these differences to the inertia of the controlling weight.
(7) There is a great satisfaction in being able to slam down a vigorous chord, hand and foot working in unison.
(8) In the earlier experiments the connection between the lever and the bellows was made first with strings and tapes, and afterwards with wires passing over pulleys. It was found, however, that the stretching of these connections greatly interfered with the effects and led to the production of harsh results, and the connections frequently broke.
(9) The best accentuation of particular notes in chords is obtainable when the notes reach the openings in the tracker board at exactly the same instant. When they are cut unevenly it is often very difficult to accentuate at will either the upper or lower notes of a chord.
(10) With experience it is possible to learn the exact kind of effort required to accentuate a note in any part of the scale, and thus to obtain marked differences between the treble and bass parts of a comparatively short chord.
(11) Where a note or chord is repeated a number of times in rapid succession it is advantageous to hold the controlling lever firmly. This obviates all the strain on the ankles in pedalling, which under ordinary conditions is considerable.
(12) In every case the exertion of pedalling is greatly reduced, not improbably by about 50 per cent. (13) Some players have separate regulating bellows for the bass and treble parts, but this does not interfere with the working of the device.
(14) A very small effort often produces a considerable difference in the effect. It is possible to emphasise a particular note or chord by a suitable stroke of the pedals alone, but the lightest possible touch of a finger applied to the lever will often produce a conspicuous improvement in the effect.
(15) Experiments with pianos of different makes, both upright and horizontal, operated by either detachable or interior players, lead to practically identical results.
Although I have been trying for a long time past to account theoretically for the observed effects, the results are still far short of finality. It is clear that neither Helmholtz's nor Kaufmann's mathematical investigations fully suffice for the purpose. There are, however, other difficulties. One is that, although it is easy to observe differences of effect which are, as a rule, quite conspicuous, it is not as easy to define exactly in what these differences consist. Again, the success of a piano-player as a musical instrument largely arises from the fact that the manipulation of the various controls, both for tempo and expression, soon becomes intuitive. A great deal evidently depends on the elasticity of the muscles of the hands and feet. It would be very difficult to ascertain precisely the effect of differences in this elasticity on the tension in the playing pneumatics while a note is being sounded. In short, it appears probable that a complete dynamical theory of the observed effects will involve investigations of no small degree of difficulty. The mere engineering of this control device into a form in which it can easily be adapted to any internally fitted player without interfering with its use for hand piaying, has given Mr. Ireland a great deal of trouble. It is now important that the experiments should be repeated by a number of different independent observers, and their experiences compared; until this is done it would be futile to proceed much further in seeking a theoretical explanation.
The average children of player owners will not wish to spend much time in acquiring manual dexterity with scales and five-finger exercises. In place of the present "practising," they will practise exercises in player manipulation, and begin by learning the meaning of the expression marks on the roll. The exercises will be mainly devoted to:
(1) The control of the speed regulator and the acquisition of the subconscious or instinctive faculty of playing every note or chord at the desired instant. Practice in accompanying.
(2) The production of differences of expression and touch, including those described in this lecture, and the acquisition of the power of accenting parts of chords in any part of the scale. The pupil must not be satisfied until he has learned the exact action corresponding to every note on the keyboard. For school practice automatic accent perforations and separation of bass and treble halves must be forbidden. A school prize should be given for the best rendering of some composition.
The pupils will, however, require some familiarity with the structure of music, and musical notation. For this purpose there will be needed a scale to be placed in front of the tracker showing the black and white notes, and in addition special rolls marked in such a way as to illustrate :
(1) The rulings of the treble and bass clef in the ordinary staff notation.
(2) The relative value of semibreves, minims, crotchets, quavers, etc., and the corresponding rests. (3) The distribution of the sharps and flats in different keys.
(4) The meaning of such terms as staccato, legato, arpeggio, trills, etc.
(5) The lengths of the various musical intervals, such as major third and minor fifth.
Finally, in order to acquire practice in reading music, the pupils may learn to cut their own music rolls. Appliances for this purpose are already obtainable, and will doubtless become common in the future. A school class in roll cutting should prove an efficient