Lieut.-Col. Sir John Underwood Bateman-Champain (1835-1887)

Journal of the Society of Telegraph Engineers, Vol. VIII - 1879

The Seventy-Eighth Ordinary General meeting of the Society was held on Wednesday evening, April 23rd, 1879, at the Institution of Civil Engineers – the PRESIDENT, Lieut.-Colonel BATEMAN-CHAMPAIN, in the chair.

The proceedings commenced with the reading of the following paper:-

RECENT IMPROVEMENTS IN PROFESSOR BELL’S TELEPHONE

By ADAM SCOTT.

Ever since Professor Bell introduced to this Society his invention of the Articulating Electric Telephone, the interest felt by the members in that instrument, and in the numerous discoveries that have followed in its wake, has been so strongly shewn that I have felt it not out of place to draw your attention to the recent improvement made by Mr. Frederick Allen Gower in the instrument commonly called the Bell Telephone. I do so all the more readily, as I believe that since Professor Bell lectured in this room, about eighteen months ago, no further communication as to the construction of that telephone has been read to the society, and it might therefore seem to have been stationary all this time.

When I speak of the instruments commonly known as Bell Telephones, it will, no doubt, be understood that I refer to those in which permanent magnets are used. At the same time, it would not be right to forget that the first Telephone he invented was an electro-magnet or Battery Telephone, and that this has been the parent of several forms of instruments introduced by subsequent investigators. As, however, the Professor selected the Permanent Magnet Telephone for circulation, on account of its greater simplicity rendering it more suitable for general use, it is perhaps not to be wondered at that the public have associated it more specially with the inventor’s name.

In America the Bell Telephone has had an almost unparalleled success. The proprietors do not sell any instruments, but simply let them out on hire at an annual rental. Notwithstanding this seemingly disadvantageous practice, I understand that the present number of telephones thus let on hire is in excess of 26,000, which is an enormous number considering the comparatively short time since the invention was introduced. And the business seems to be going on progressively, the further issues being now about 2,000 monthly. In all the large cities of the United States the Bell Telephone Company have established the central office or exchange system, by means of which any one subscriber can, at almost a moment's notice, be put into communication with any other subscriber. In Chicago, for instance, the number of subscribers is over 700, and so much are the facilities for inter-communication appreciated and availed of, that, as I learn by last advices, the "calls" through the telephone upon the central office number over 8,000 daily.

These figures show clearly that our American brethren - perhaps on account of their admitted spirit of enterprise, or go-aheadedness - are much more appreciative than we are of the benefits to be obtained from the telephone. Perhaps, also, it may be that there bas been much better management of the business in America than in this country. Whatever be the cause, the fact remains that the telephone has not yet been adopted in the United Kingdom to any appreciable extent. I do not hesitate to say that there are not anything like as many as 500 telephones in actual daily use, as compared with the 26,000 on the other side of the Atlantic.

This, in some respects, is to be attributed to ignorance on the part of the great majority of the public. Notwithstanding that the telephone and its wonders have perhaps been the subject of more newspaper paragraphs than any other invention, there is no question I have had so frequently put to me by well educated people than “Do you think it will ever be a practical instrument?" or “Will it work more than a few hundred feet?" Yet most people say they have beard or seen the telephone; it seems to me, therefore, that this melancholy state of the public mind is due to the fatal facility with which telephones of a kind can be made. When people first got over their unbelief at the strange Yankee rumours that reached our shores, they eagerly read the descriptions given of the wonderfully simple instrument, and if they did not set to work to construct it for themselves, they purchased it from the numerous pirates that sought to make a profit out of the public curiosity, regardless of the quality of the instruments thus sold. Those who know with what care and exactness in every respect a telephone requires to be made in order to give satisfaction, can easily understand how the public have arrived at the opinion that it is a pretty scientific toy, but little else. The proprietors of the telephone in England are not altogether to be absolved from blame in this matter - the instruments they have supplied to the public, although infinitely superior to those just referred to, were not such as should have been issued. In the hands of non-electricians, the faults of their manufacture led to the instruments becoming frequently silent, and to their requiring such constant attention on the part of skilled persons, that they often became a nuisance instead of a convenience. This suicidal policy has, I regret to say, been continued until lately, with the result that the telephone has, through mismanagement, failed to make that progress in general estimation, and in practical application, that its intrinsic merits entitled it to.

In the United States this error was not committed. It was early seen that for practical purposes the first form of the instrument must be much improved. More than a year ago the wooden hand telephone was abandoned, and greatly superior instruments substituted. For the purpose of comparison I have laid on the table specimens both of the wooden telephones issued in this country, and of the American ones that have been so justly successful.

There is no necessity in a meeting like this to explain the principles and action of the Bell Telephone. It may be useful,[ however, to explain somewhat in detail, what I may fairly call the disadvantages under which it laboured in this country.

The most noticeable drawback to its use has been the comparative faintness of the sounds produced. While the articulation was very distinct, the volume was small. As a consequence, it was simply impossible to use the instrument with beneficial results in places where the utmost quiet did not prevail. As this necessary quietude is not a condition easily attainable in the majority of business offices, it followed that the field for the utilisation of the telephone was thereby much narrowed. Even in places ordinarily quiet, the sound of another person talking in the same room was sufficient to prevent the listener hearing well; and under the most favourable circumstances there was so much strain upon the attention required that communication through the telephone was apt to become somewhat fatiguing.

This want of volume was primarily caused by the smallness of the magnets used, and their extreme weakness. It seems to have been thought that any penny magnet was sufficient for the purpose of generating those currents, whose very weakness was adduced as one of the marvels of the instrument. That no greater mistake could possibly have been made will, I think, be evident later on when I shall have to show that the stronger the magnet the better the result that may be expected from it. The choice of small magnets was perhaps dictated by a desire to produce a telephone of convenient size and weight that could, without much weariness, be held to the ear for some time if necessary. The combination of a fixed telephone, with a powerful magnet and a flexible speaking tube, does not seem to have suggested itself. Such a combination would have got rid of the disadvantage arising from the faintness of the sounds produced, and besides would have done away with the annoyance caused by the use of flexible wire conductor cords, which are a necessity with hand telephones. The wires in these cords, especially where not very tenderly handled, are constantly breaking, and thus interrupting the communication, without there being any external indication of the cause to enlighten the uninitiated. Such broken wires often momentarily come together again, and thus communication will be temporarily restored, to cease perhaps in the middle of a sentence, as the movement of the user causes the broken ends again to separate.

These breakages not only cause annoyance, but they occasion much trouble, as nine times out of ten they necessitate the sending for some one who understands the cause, and the waiting until he can come with new cords to replace the defective ones.

Another complaint against the telephone (I speak of experience in this country only, because it is not the case in America) owesits origin also to the weakness of the magnets. In order that the maximum effect shall be obtained, it is necessary to adjust the diaphragm exceedingly close to the pole of the magnet. The result is, that in I am afraid the majority of instances, any alteration of temperature, or of moisture affecting the wooden cases, causes the diaphragm to touch the magnet. Once touching, it is sure to remain in that position, and, being no longer free to vibrate, fails to produce sufficiently audible sounds. This, however,[is a defect in manufacture that ought not to occur, but it is well to point it out, as it is only by knowing what such defects are and their causes that we can find a remedy.

There is another disadvantage that the telephone hitherto has had to contend against. The sound produced being so faint, it was necessary to draw attention to it by means of separate apparatus. Magneto Bell-Calls are largely used in America, and were introduced into this country, but for our credit I regret to say that in almost every case (and I know of numerous ones) these Magneto Bell-Calls were a signal failure. Why they have been a success in the States, but a failure here, can only be set down to bad manufacture. Battery Bell-Calls, therefore, became a necessary adjunct to the telephone, thus adding a very undesirable complication to what was otherwise so simple, not to speak of the extra cost they entail. Bells and Batteries for a short line cost at least £4, which is large as compared with the actual cost of the telephones themselves. Such calls necessitate many connections, contacts, and switches - all of which increase the chance of something going wrong - and are so complicated and technical in nature, that both in erection and maintenance the intervention of a skilled person is absolutely required, and until such assistance is obtained (very often from a distance) the apparatus in the event of mischance is useless.

I have alluded to the fact that some of the disadvantages I have described as hitherto attaching to the telephone in this country are not common to those used in America. The two kinds of instruments used in the States, and which are laid upon the table, are certainly great improvements upon the original telephone. They are very superior and reliable instruments. As, however, they have been largely in use for more than a year, they are not exactly recent improvements. I will not, therefore, take up time in dwelling upon them.

The particular telephone which I have the pleasure of introducing to the notice of the Society this evening is the result of recent improvements devised by Mr. F. A. Gower. It will be remembered that this gentleman, about a year ago, exhibited his telephonic harp to the Society. He was formerly associated with Professor Bell and the American Telephone Company from the early days of the invention, and is now engaged in the telephone business in France. Mr. Gower has for several months devoted himself exclusively to the study of the various means by which the disadvantages I have described could be obviated, and to the improvement of the instrument in every detail. I am glad to be a testimony to the perseverance and ability with which Mr. Gower has pursued his investigations, and of congratulating him upon his success, of which I hope the Society will be able to judge for themselves.

Mr. Gower has produced a telephone so powerful that I have no doubt music, and even in some degree, spoken words will be audible all over this room. When it is provided with a funnel for collecting sound, as in the case of the instrument on the table which we shall use this evening, conversation can be carried on without speaking or listening closely at the telephone. And so sensitive is it that all sounds made in the room, however large in which it may be, are distinctly audible at the other end of the line. I have no doubt that whatever I may say at as great a distance as I can get from the instrument will be heard by my friend at the other end, and, I hope, so distinctly as to be repeated by him.

Such experiments are no doubt interesting in a lecture room as showing the delicacy and sensitiveness of the telephone, but for practical purposes they count for little. What is wanted is that combination of volume with distinctness that will make the instrument useful and reliable not only in a busy office, but in factories amidst the working of machinery, and on the field in military operations. A telephone that speaks so loudly as to be heard over a room is for most purposes not only not necessary, but has its disadvantages, by depriving the communication of that private nature which is a desideratum, especially as the sender of the message cannot possibly tell to whom and to how many people he might thus be unintentionally talking.

When we come to examine the instrument as shown upon the table, and, also illustrated by the annexed diagrams, the first thing that strikes one is, that after all it is a simple Bell Telephone, composed of a diaphragm and horse-shoe magnet, produced with two soft iron poles on which are insulated wire coils. Wherein, then, it may be asked, lies its peculiar excellence? and the answer is, in the perfection of each part, and in the combination as a whole. When our attention is drawn to the fact we will find that in every detail a different form is used to any which we see in ordinary telephones. Let us therefore proceed to an examination of each part, beginning with the magnet (O). W e see that the ordinary form of the horse-shoe magnet has been abandoned, for one of an entirely novel shape, an arc of a circle, with its chord; the division between the poles being in the centre of the latter. The magnet is made out of a peculiar kind of French steel, very porous in its nature, and has been magnetised in a special manner, which is at present the only secret of the manufacture. The result of the combination is a permanent magnet of great power, capable of lifting at least ten times its own weight. This strength is a most important feature, and has not been arrived at except after much patient investigation and a multitude of experiments. There are very few people here who could by a fair outward pull pluck the armature from the magnet I hold in my hand without very great difficulty, and I need scarcely point out the striking difference between such magnets, and those formerly used in the construction of telephones.

The magnet is provided with soft iron pole pieces, but the usual cylindrical shape has been abandoned, and instead we have poles which present to the diaphragm a narrow oblong surface, as long as the width of the magnet, and about one eighth of an inch in breadth. The coils follow the shape of the poles, and are each of about 60 ohms resistance. This peculiar form allows the poles to be brought much closer together than in other telephones, and they certainly attract the diaphragm more strongly than in ordinary telephones. The coils, as a mass, are also much more within the most powerful part of the magnetic field, an advantage that must be obvious to all.

The diaphragm, which is 3¾" in diameter, is much thicker than usual, so much so that, notwithstanding the great strength of the magnet, a very close adjustment near to the poles is practicable without any chance of contact, and the closer the adjustment the more sensitive does the instrument become. The diaphragm is very firmly held by a brass ring screwed into the cover of the telephone.

The whole apparatus is enclosed in a metal box, partly for the purpose of strength, partly to avoid the increased vibration and consequent reverberation that accompanies the use of wooden boxes, and partly because there is less alteration from expansion and contraction, and moisture cannot be absorbed. To the cover of the box a flexible speaking tube is attached.

I have now to draw your attention to one of the most important features of the instrument, and one which is entirely the invention of Mr. Gower. The telephone gives its own call, a call sufficient in most cases to obviate the necessity, the expense, and the complication of electric bells and batteries. In the diaphragm a small hole is cut, and to the reverse side of this is soldered a small box or trough (A) containing a metal tongue or reed (T). When the user wishes to call attention at the other end of the line he does exactly as he would do with an ordinary speaking tube, with the use of which everyone is familiar. He blows into the flexible tube, and the air passing through the orifice in the diaphragm vibrates the reed, and then escapes by a vent made in the side of the box. The sound produced is very distinct and pronounced, and the diaphragm is put in intense vibration, due not only to that sound, but to the mechanical communication of the vibration of the reed caused by its being attached to the diaphragm. At the receiving end the call is very satisfactory, and of this the meeting will be able to judge for themselves.

Mr. Gower's telephone is not the only one which contains its own call, though decidedly the simplest and best. Mr. Siemens, of Berlin, uses a reed temporarily held in the mouthpiece of the telephone, by which not only is the sound produced by the vibration used, but it is made to act on a small ball which produces a series of blows upon the diaphragm or disc, the result being an audible signal at the further end of the line. This invention requires the telephone when not in use to be kept in an upright position.

Another method of making the instrument make its own call has been patented by Mr. A. F. St. George, of the India Rubber Company. Outside the coil of the telephone another coil of thick wire is wound, an intermittent current from a battery being passed through this outer primary coil, corresponding currents are induced in the inner coil, which as usual is permanently connected with the line, and cause vibrations of the diaphragm at the distant telephone audible at a considerable distance. The vibrations are rendered intermittent by means of an armature vibrated by an electro-magnet upon contact. The switching in and out of circuit of a bell-call is thus obviated.

In concluding, let me call attention to the great simplicity of the instrument. It consists of a magnet, coils, diaphragm, reed, the containing box, and a speaking tube - no batteries, no bells, no switches. That this simplicity is a very important matter will scarcely be disputed, and when added to it one finds that the telephone has great volume and distinctness, that it is strong and cannot well get out of order, contains its own signal and does away with flexible conducting cords, I am sure that the Society will agree with me that a great advance has been made in the department of magneto- telephones, and an instrument been produced that may safely be issued without fear that any person of ordinary intelligence would not be able to fit it up if furnished with very few and simple directions. In these respects it differs from all other telephones yet brought forward, and, I have no doubt, has a good future before it.

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The President then invited discussion on the paper.

Sir William Henry Preece (1834-1913)

Mr. W. H. PREECE: As, perhaps, I have taken more interest in the telephone than most men, I may be allowed to commence the discussion by a few remarks. I have been extreme1y pleased with the performances to-night, and what astonished me more was that there is so little absolutely new in the apparatus, and yet that little new has produced such excellent results. One or two things strike me, in nearly all experiments with the telephone, that is, that every disc of a telephone has its own peculiar dominant note peculiar to each instrument, and when we heard the duet on the cornets, and when they were played singly, it was evident that certain notes gave out sounds louder than others. Those louder sounds agreeing with the dominant tone of the disc, in order to obtain the greatest effect on the speaking telephone it is a good plan to find out that dominant note and speak on that note; and it is because some men have a voice in ordinary conversation which strikes upon that note, that their voices are louder than others. My assistant, Mr. Wilmot, has a remarkable knack of striking the dominant note of the telephone, and had he been where Mr. Woollaston was, I am certain his voice would have been heard allover the room.

Now, Mr. Scott in his paper has referred to the very extensive use of the telephone in America, and he said at this moment no fewer than 26,000 were paying annual rents, and he also said he did not think there were more than 500 in daily use in England. I think on the latter point he is wrong. Probably the Telephone Company do not reap the benefit from more than 500, but there are others who have nothing to do with the Company, who are using them to a large extent. It is not to the credit of the persons using them, but my impression is that there are at least 25,000 in use in England. This speaks either badly for the morality of the English nation, or it speaks worse still for our patent laws. No doubt the first thing after a patent has been secured is to see if the thing cannot be done in another way, or if not, to study how to avoid payment of the royalty. The telephone has been used in this country to a large extent, but there does not appear to be the want of it in England that there is in America. One thing which strikes one in America is the enormous extent to which they apply the telegraph and the telephone for their own domestic purposes. In Chicago, where there are from 7,000 to 8,000 calls daily, there is scarcely a house which has not in its hall a call-bell, by which you may despatch a message for a doctor, or a porter, or anything else you want, and the reason they are driven to that is – necessity being the mother of invention - that it acts as a substitute for servants. Here we have no difficulty in getting servants if we pay them, but the difficulty in America is to get "buttons" at any price to run about for you as in England, and the result is the absence of servants has to a certain extent compelled the Americans to adopt this system of telegraphy for their own domestic purposes, and the telephone is to be found in almost every house as the only available substitute for the old system.

Few have worked at the telephone much more than I have. I have one in my office, but more for show I as I do not use it because I do not want it. If I want to send a message to another room, I use a sounder or employ a boy to take it; and I have no doubt that is the case with many others, and that probably is the reason why the telephone has not been more adopted here. The efficiency of the instrument in England has been seriously interfered with by those fearful inductive effects which are not felt to the same extent in America, because they have no long underground lines, and they do not use that fast-speed apparatus which produces such a tremendous roar with us. It is impossible with 60 wires in underground pipes to speak through the telephone, the inductive effects being so great.

The management of the telephone in England has been singularly unfortunate. There has been no policy struck out, there has been no administration to bring the thing before the public in a proper way, and its representatives were not remarkably successful in bringing it before the public, and the result is, it has stopped as much from inefficient management as from inefficient apparatus.

There are one or two things introduced here as new which are not new: for instance, this flexible tube. I have had that in my office for twelve months. The telephorie in my office was supplied with a tube of this kind, but though it aided conversation to a certain extent, it induced mixture of sounds or retardation, which interfered with clear articulation, and I noticed that speaking through a tube was not so clear as through the cone. The cone is not quite new, for when I had the pleasure of bringing before you the beautiful discovery of Professor Hughes - the microphone - I used a cone of this description, and every one in the room was able to hear Professor Hughes speak.

The principal feature in this instrument is, first, the form of the magnet, the way in which the poles are placed, and the particular form of the coil pieces. These are to me new. I have seen a good many forms of telephone, but I have not seen that. I think the effect is due, first, to the form of the magnet, and secondly, to its extreme strength. One must be surprised to .a magnet with such portative power as we see here. I don't know that I have ever seen one which would hold more than four or five times its own weight - and practically we are content with one which holds its own weight - but here we have one which holds ten times its weight, and doubtless to that is due the loudness of the sounds we get.

One thing puzzles me, and that is, why the fixture of this reed in a particular part of this disc does not interfere with the clearness of the articulation. A curious discussion has been going on in the scientific journals upon the theory of this instrument. There are two theories referring to the action of the telephone. The one attributes the emission of sound entirely to the molar motion of the diaphragm - that the vibration backwards and forwards of the mass of the disc produces these sounds. The other theory is that of molecular action - that the sounds are produced by the molecular vibrations of the magnet itself, and these are imparted to the diaphragm. Thus there are two distinct theories - one the molar and the other the molecular. The molar theory has been hitherto accepted in England, and it is by some supposed to be the theory first announced by Professor Bell himself; but when I was in America Professor Bell preferred the molecular theory. The molar theory was first enunciated by myself before the British Association at Plymouth; and I made a great number of experiments to try to satisfy myself that the sound was really produced by the vibration of the disc, and I had no difficulty, when the sounds were loud and by using wind instruments, in feeling the absolute vibration of the disc.

On the other hand the Count du Moncel and many others are violent supporters of the molecular theory. That theory, however, I think, is rather disturbed by what we see here. I should have thought the fixture of this reed would have interfered with its articulation, but I understand Mr. Gower found no difference in the instrument when the reed was taken off it.

The chief merit of this instrument is its simplicity, but I am not sure something has not been lost in endeavouring to get loudness. I do not myself think we want loudness. In an instrument exhibited by Professor Tyndall loudness was carried to excess. The telephone of Edison is based upon the electro-chemical principle, and by the application of that to the disc, sounds were produced loud enough to fill the theatre of the Royal Institution, but the loudness was obtained at the expense of articulation. Though the articulation was good, it was not so clear as from these little telephones with small discs, and I am inclined to think from what I have heard to-night, the loudness of this telephone is obtained at the expense of clear articulation. When you listen closely you hear what Mr. Woollaston says, but when you go to a distance and try to make out what he says you fail to do so. It is like the phonograph. I have not yet seen a phonograph which faithfully repeats the human voice. And some of you will remember at the Royal Society I challenged the whole body to repeat from the phonograph any part of two sentences which I repeated. I spoke them clearly and distinctly, and yet there was not a man who could repeat a single word. It is a defect when we attempt to get loud sounds, but you do not want to get an instrument to shout out. You want sound loud enough to hear yourself. If you want to send a secret message from your office you don't wish everyone to know what is going on. I do not see any practical utility in these loud sounds. I think this endeavour to get loudness is a mistake. What you want is clear articulation. There is no telephone that I know of which produces the letter S; it comes from the instrument as a sort of breath; it fails to transmit the sibilant sounds altogether. Hence in speaking through the telephone absence of clear articulation and want of clearness render repetition so frequent, that those who have used the telephone, regard it more as a scientific toy than as a real practical instrument.

Major-General Charles Edmund Webber (1838-1904)

Major WEBBER:- I think the last speaker has left me the opportunity of congratulating Mr. Scott upon having brought before us a most interesting paper, enabling us to discuss a subject which for upwards of 18 months has not come before the Society, and yet which has in the meantime been making a great noise in the world, and also has set many telegraph engineers here and abroad thinking and inventing. I think, whoever is the inventor of the telephone as a means of communicating articulate speech has conferred a boon on society, which I am sorry to say Mr. Preece does not seem quite to concur in. The statistics we have heard of the telephone in America, and what we know is doing in France and Germany, show that this means of communicating articulate speech, and placing persons who wish to speak to each other face to face, is spreading rapidily (sic), and will soon make an immense revolution in the facilities for carrying on business and producing economy in its operations. I cannot help thinking from the few experiments I have made myself, probably in a short time means of communication by articulate speech will be established, and will be in common use in many places by means of a carbon transmitter and a magnetic receiver. In the carbon transmitter an animal tissue diaphragm is used, by means of which I have been able to speak through 70 miles of line with perfect clearness, although it was in a low tone of voice. But this experiment had a condition which could not be got over if it had not been for this animal tissue diaphragm. This 70 miles of line was on poles carrying a number of other wires, and in one place for some distance passed through an ordinary telegraph underground cable containing some 20 or 30 wires, all of which were at work at the time. The difference between the sound of voice when this transmitter was used and the sound when the ordinary magnetic transmitter was used, was this - that in the one the noise from the induction did not interrupt the voice at all, or only to such a trifling extent as not to interfere with it, whereas when the magnetic transmitter was used the sounds produced through the telephone by induction were such that the voice could scarcely be understood.

With regard to the molar and molecular theories, although we have very little evidence with regard to the latter, I do not think the opinions of such a scientist as the Count du Moncel can be so easily set aside as has been suggested, more particularly as in the telephone invented by M. Ader, who submitted it to the Count before he patented it, such marvellous results were produced. In that telephone the principal feature is this, the core is not magnetic at all, but consists of a piece of iron subjected to torsion, strain, or tension. The diaphragm which is used, the same nearly as the ordinary magnetic telephone, produces the sounds. As soon as the torsion or strain is removed the piece of iron ceases to act. This appears to me to favour the molecular as against the molar theory.

There is one matter of interest to telegraph engineers which I would refer to, that is, that the telephone is useful as a means of helping line men to remove faults on ordinary overhead telegraph lines. I remember on a Parliamentary Committee of the House of Commons on Postal Telegraphs the question was asked why telegraph linemen who failed to remove faults should not be able at any time to communicate with the station at the end of the interrupted wire, and thus be able to ask the office whether the fault continued. The answer of the telegraph engineer who was examined was that it was not an arrangement which was likely to succeed. But at the present moment the line men of the Post Office Service, under my superintendence, of their own accord have made a telephone of their own, which they use in a very ingenious way for the removal of faults. They leave a telephone at the faulty end of the line, and as they proceed they attach other telephones to the wire. In this way they communicate with the clerk in. the office, and by that means a number of faults are removed by the line men, who might otherwise traverse the line without seeing those faults.

Lord LINDSAY: I want to say a word about Mr. Preece not using this instrument, and my own experience with regard to it. Professor Bell sent me two of these telephones, and since that time they have been daily in use in communicating between my house and my laboratory and observatory, a distance of about a quarter of a mile. I have found them of great use. In the old days I had a telegraph, and there was time lost in calling and then signalling. Now I get my messages delivered in a moment. I know who is at the other end by the sound of the voice. And I find it of great value. As to having large and powerful magnets, I agree with that. I used a compound horse-shoe magnet, about a foot long – a very heavy magnet with coils on the end of the poles of about 45 to 50 ohms resistance - but I found I did not get good articulation, although I obtained an immense collecting power of sound. Talking going on in the laboratory 100 feet from the telephone was audible at my house, a quarter of a mile distant, quite distinctly. Without being able to hear the exact words, I could tell who was speaking in the laboratory.

As to the question of induction: going from the laboratory to the observatory I have a cable of 16 or 18 wires, and another cable communicating with my house of 8 wires. On the 16-wire cable I have 5 or 6 circuits which are constantly at work in different parts of the observatory. My telegraph circuit going to the house comes within 6 feet of this cable, and I am able at the house to hear the burr at the end of the current at any time, as it is continually going on from the Meidinger cells. I have not found a means of getting rid of this induction. It is said by passing telephone wires through tubes it can be done.

With reference to the articulation of the plate of the telephone shown us this evening being affected by the reed placed on it, I imagine it would not affect articulation, but it would very much change what is called the fundamental note. If this reed is placed in a different position I imagine the vibration of the plate would not be affected except so far as to change the fundamental note; so that if Mr. Preece finds that the fundamental note is altered when this vibratory tongue is removed, I fancy he would have to pitch his voice in a different key to produce the same effect.

William Edward Ayrton (1847-1908)

Professor AYRTON - Mr. Preece in his remarks has alluded to a very important point in connection with the telephone and phonograph, namely, the difficulty that has been experienced in increasing the volume of the sound without diminishing the clearness of the articulation. This consideration is in reality intimately connected with an important feature that characterises the diaphragm of the telephone and phonograph. It is quite clear that in order that the receiving diaphragm may faithfully reproduce all the vibrations imparted to the sending diaphragm the natural vibrations of each must be unimportant. Now, it is rather interesting that before the invention of the telephone Professor Perry and myself were engaged in the solution of a problem which at first sight might appear to have no connection with telephony, but which really has an important bearing on the subject. We were investigating how to make the best form of seismograph or earthquake recorder. Now a good seismograph must be an instrument which records every vibration, small or great, imparted to it by the trembling of the earth, but which has no preponderating vibrations of its own to interfere with the earthquake record. Although many seismographs had been devised prior to our investigation of the subject in 1877 no one had been invented fulfilling this important condition. Mathematical analysis, however, led us to this solution of the problem of constructing a proper seismograph.* If we wish to have a moving body which shall faithfully record all vibrations imparted to it, then it is necessary that the natural vibrations of the moving parts must be very rapid compared with those which it is required to record, or, if so great a rapidity of natural vibration is practically unobtainable, then the introduction of viscous friction will assist matters in causing the natural vibrations of the recorder to die away quickly so as not to preponderate over those imparted to it, and which it is its province to record.

* "On a Neglected Principle that may be employed in Earthquake Measurements." Trans. Asiatic Society of Japan, 1877, vol.v., part 1, p.181. Reprinted "Phil. Mag.," June, 1879.

Now, natural rapidity of vibration is of course attained by rigidity, so that we advocated the use of very stiff rigid springs in our seismograph, the result being that we obtained in miniature a true record of the earth's tremblings. Exactly for the same reason, but in this case as a result of natural selection, Professor Bell and Mr. Edison have been led to the comparatively rigid, naturally rapidly vibrating, membrane of the telephone and phonograph.

The other solution, however, to which we arrived - the introduction of viscous resistance - although used by Sir Wm. Thomson in his dead-beat galvanometer for cable speaking, &c., does not seem to have been tried for telephones or phonographs. But I am inclined to think that possibly, if large diaphragms of considerable rigidity and with perhaps oil-cells to give them viscosity be employed, loud and at the same time clearly articulating telephones and phonographs may be made.

As regards the two theories of the telephone, to which Mr. Preece has referred, there are on the table some rough forrns of telephones made at the suggestion of Mr. Latimer Clark on the plan proposed by M. Ader. Now although these telephones have been made as closely as possible in accordance with M. Ader's plan, which is clearly and well described in the Telegraphic Journal, I have not succeeded in getting them to work satisfactorily. At the same time, although such rough experiments as I have made rather point to the motion of the diaphragm as a whole producing the sound in the telephone, I should not care to put them forward as in any way overturning any of the fairly complete experiments made by the Comte du Moncel, and which show that the action is a molecular one.

Probably the complete explanation is, that the two actions, the motion of the diaphragm as a whole, as well as the rapid molecular extension and contraction of the steel or iron rod, are both effective in the ordinary receiving telephone in emitting the sound.

Mr. E. A. COWPER: It was stated by Professor Bell that he had a diaphragm ⅜th thick and 3 feet diameter, and spoke very well with it.

Professor AYRTON: If you have a diaphragm of large size, it is necessary to have it of great stiffness, and therefore thickness, in order that the gravest note naturally emitted by it shall be high compared with the highest note it is ever forced to emit, and which, as I have pointed out, is the condition necessary to be fulfilled in order that its natural vibrations shall not produce confusion.

Mr. ADAM SCOTT: I beg to thank you for the attention you have paid to my paper, and I am glad it has been the ground work for the remarks that have been made. I have nothing particular to answer, but when people make experiments with the telephone it is astonishing how different their experience is. Mine differsfrom Mr. Preece's. I do not find that tubes have the effect of making the sounds less clear. I tried an experiment with three yards of tube, and the articulation was better with three yards than it was with one yard. The volume was weaker, but the articulation was more clear. After what Mr. Preece has said about the subject, I shall make more experiments. In testing the articulation of particular letters, I have noticed there is a distinct difference between B and P, and D and T, but I have not noticed the peculiarity which Mr. Preece mentions with regard to the articulation of the letter S.

The PRESIDENT: I feel sure you have all, like myself, been much interested in the paper Mr. Scott has read, and that you will agree with me in returning him a vote of thanks for his kindness; and also in congratulating him on the remarkable success which has attended the experiments he has made to-night.

The vote of thanks having been unanimously accorded to Mr. Scott, the meeting adjourned till the 14th of May.

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