The ‘Telharmonium’ or ‘Dynamophone’ Thaddeus Cahill, USA 1897

Thaddeus Cahill
Thadeus Cahill
b. Mount Zion,Iowa 1867, d. New York City 1934

In 1897 Thaddeus Cahill patented what was to become the “Telharmonium” or “Dynamophone” which can be considered the first significant electronic musical instrument . The Telharmonium was an immense instrument of about 200 tons in weight and 60 feet in length assuming the proportions and appearance of a power station generator….the quoted cost was $200,000. The monstrous instrument occupied the entire floor of “Telharmonic Hall” on 39th Street and Broadway New York City for 20 years. Despite the Telharmonium’s excessive proportions the sound it produced was both flexible and novel to a degree unmatched by subsequent designers until the 1950′s, and unusually, the instrument was ‘portable’ – taking up thirty railroad carriages when transported from Holyoke, Mass to NYC. The visionary 36-note-per-octave keyboard designed around Cahill’s ideas of just Intonation were far ahead of their time musically but proved unpopular with musicians who had little time to practice on the unusual keyboard this factor eventually added to the demise of the instrument.

Scientific American vol 96 no10  9th March 1907
Scientific American vol 96 no10 9th March 1907

The Telharmonium was a type of additive synthesiser – and Cahill probably coined the phrase ‘Synthesiser’ to describe his instrument – using a electro-mechanical method to generate it’s sound. As the only way to hear the instrument in the era before amplification and loudspeakers, was to send the voltage output over a telephone line, Cahill hit upon the idea of centrally performing music and serve it over the phone network to paying subscribers in hotels, railway stations and private houses; a kind of early Victorian audio internet.


Dr. Thaddeus Cahill’s system of generating music at a central station in the form of electrical oscillations, and of transmitting these oscillations by means of wires to any desired point, where they are rendered audible by means of an ordinary telephone receiver or a speaking arc, is now embodied in a working plant situated in the heart of New York. Although this apparatus constitutes b.ut a portion of a plant that may ultimately assume very remarkable dimensions, and although it has limitations imposed by its size, the results obtained are so promising, that many applications have been made by prospective subscribers for connection with the central station. When a larger number of · generators and keyboards is installed, as they doubtless will be in due time, there is no reason why the telharmonium, as the invention is called, should not give the subscribers all the pleasures of a full symphony orchestra whenever they wish to enjoy them. At present ‘ very beautiful effects are secured on a . less elaborate scale, but in eveI\ly way comparable with those of a good quintet.. And several additional keyboards now in building at Dr. Cahill’s works at Holyoke, Mass., where the New York plant was built, are nearing completion, and will probably be in service at Broadway and Thirty-ninth Street in the course of another month or two.

Perhaps the feature which most astonishes the technically Uninformed man when Dr. Cahill’s invention is first exhibited to him is the fact that music in the ordinary sense of the word, in other words, rhythmic vibrations of the air, is not produced at the central station. The vibrant notes of the flute, mingled with the clarinet or viol-like tones which are heard at the receiving end of the wire, spring from no musical instrument whatever. Nowhere is anything like a telephone transmitter used, although the electrical oscillations which are sent to the receiver and there translated into audible vibrations are quite like those set up in an ordinary telephone circuit, except that they are enormously more powerful.

Briefly summed up, Dr. Cahill’s wonderful invention consists in generating electrical oscillations corresponding in period with the acoustic vibrations of the various elemental tones desired, in synthesizing from th ese electrical vibrations the different notes and chords required, and in rendering the sYnthesized electrical vibrations audible by a translating device.

In the New York plant the electrical vibrations are produced by 144 alternating dynamos of the inductor type, having frequencies that vary from 40 to 4,000 cycles. These alternators are arranged in eight sections or panels, each inductor being mounted on an ll-inch steel shaft. One inductor dynamo is used for each note of the musical scale, each generator producing as many electrical vibrations per second as there are aerial vibrations in that note of the musical scale for which it stands. The fixed or stator part of each dynamo carries both the field and armature windings ; the rotors are carried on shafts geared together, the number of teeth ( pole pieces) on the gear wheels corresponding with the number of frequencies to be ob-. tained. Because the rotors are geared together, the frequencies are fixed and tuning is unnecessary. The alternators are controlled each by a key in a keyboard upon which the musician plays. Each key serves to make and break the main eircuit from seven alternators, not directly, but through the medium of plunger relay magnets wound with layers of enameled wire. Only feeble and harmless currents are needed to control the relay magnets, by which the task of making and breaking the currents from the main circuits is r’eally performed. No appreciable ‘ time elapses between the depression of a key and the closing of a main alternating circuit, so that the keyboard is as responsive and sensitive as that of a piano. The elemental notes generated by the . 144 dynamos cannot alone be used to produce the most pleasing musical effects.

Why this should be so becomes apparent from a consideration of some Simple principles in acoustics. If a wire be stretched between two points A and B (see the accompanying diagram) and plucked or struck, it will vibrate above and below the line A, B and give what is known as a fundamental tone. This fundamental tone is without distinctive musical character or timbre, and would sound the same in all instruments, so that one could not distinguish whether it came from a violin or a piano. In addition to its fundamental vibration between its pOints of attachment, the string undergoes a series of sub-vibrations above and below its own normal curve, which it will pass at certain points, nodes, dividi????g it into equal parts. Thus in the accompanying sketch, A, 0, B and A, D, B represent the fundamental Vibrations, and A, E, 0, F, B, the first sub-vibration intersecting the fundamental vibration at the node 0. Again, the string may vibrate in three parts, four parts, five parts, etc. The effect of the sub-vibrations is added to the effect of the fundamental vibration, and their total effect is heard in the distinctive quality or “tone Color,” as it is called, of the particular instrument played. The sub-vibrations are known as the upper partials or overtones, and generally speaking, they are harmonious with one another and with the fundamental tone. That very elusive and uncertain quality called timbre is dependent entirely upon these overtones. By properly controlling the blending of the overtones and the elemental tones, it ought to be possible to. imitate the characteristic timbre of any musical instrument. This Dr. Cahill has in a large measure succeeded in accomplishing.

“Tone mixing,” as this building up of harmonious notes and chords is called, is effected in the telharmonium by superposing the simple or sinusoidal waves of the alternators. By means of bus-bars the oscillations of the ground tones are all brought together in one circuit, those of the first partials in another circuit, those of the second partials in a third circuit, etc. The actual blending is done by passing the various oscillations through a series of transformers. In order to understand how a chord is blended, we must begin at the keyboard. As soon as the performer depresses his keys, the bus-bars electrically superpose the ground tone currents , through the primaries of closed-iron magnetic circuit transformers, the secondaries of which are jained in circuit with impedance rheostats governing the strength of the currents, which rheostats are controlled from the keyboard by means of stops. Similarly the bus-bars superpose the first, second, third, and other desired partials in separate circuits. The composite ground-tone a’nd overtone oscillations thus produced in the secondaries of the transformers are next passed through the primaries of an open-iron magnetic circuit transformer, in the secondary circuit of which a current is produced composed of all the ground tone and overtone frequencies of the particular chord under consideration. This secondary current is in turn passed through the primary of an air-core transformer, and the resultant secondary current is converted by telephone receivers or speaking arcs into the musical chord desired.

In order to listen to this musical chord, the telephone receiver is not held to the ear. It would be bad for the ear if it were, when a loud note is sounded. The current of the receiver is literally thousands, and at times millions of times stronger, measured in watts, than those to which an ordinary telephone receiver responds. Whereas less than six tenmillionths of an ampere are sufficient to produce a response from an ordinary telephone receiver, a current of an ampere is sometimes used in the Cahill system for an instant when loud tones are produced.

The composition or quality of a note or chord is controlled by eight rheostats called stops. By skillful manipulation of the stop rheostats, it is possible to obtain very accurate imitations of the wood-winds and several other orchestral instruments. Imitation, however, is hardly the right word ; for the notes are built up of exactly the same components as the tones which come from the reaJ instruments. Furthermore, beautiful effects are obtained that cannot be produced on any existing instrument. These stop rheostats control merely the timbre or quality of the music produced. Fluctuations in volume are produced by “expression rheostats.” Both stop and expression rheostats are constituted by impedance coils, differing however in mechanical construction. The stop rheostats are manipulated very much like the stops of an organ, and the expression rheostats like the swell. Unlike an organ swell, however, the expression rheostats are used not only for producing captivating crescendos and diminuendos of individual notes and chords, but also in reproducing the peculiar singing tremolo of the violin and ‘cello.

The rather complex system of transformers described serves not merely to blend partials with ground tones, but also to purify the vibrations corresponding with the different sets of partials by purging them of their harsher components. The air core transformers, fur thermore, permit the selection of voltages according to the resistance which the final current will encounter. Inasmuch as each keyboard controls ground-tone and overtone mixing devices, it is possible to produce notes of the same timbre or of different timbres. Excellent orchestral effects can, therefore, be obtained by causing the one keyboard to sound wind instruments, such as oboes, flutes, clarinets, or horns, and the other to sound the tones of the violin or other stringed instruments.

From this necessarily cursory consideration of the telharmonium, it is evident that the music is initiated as electrical vibrations, distributed in the form of electricity, and finally converted into aerial vibrations at a thousand different places separated hundreds of miles, it may be. No musical instruments in the sense in which we understand the word are used. Not a string, reed, or pipe is anywhere to be found. The vibrations produced by the performers’ playing are wholly electrical, and not until they reach the telephone receiver can they be heard. The telephone reo ceiver acts for us as a kind of electrical ear to hear oscillations to which our own ears are insensitive. When Mark Twain heard the telharmonium, he fancifully suggested that the military parade’ of the future would be a more beautifully rhythmic procession than our present pageants. The usual military bands heading the various regiments and playing marches, not in unison, although the same in time, will give place to musical arcs disposed along the line of march, all crashing out their stntins in perfect time. The soldiers who will march in that future parade win all hear the blare of invisible electrical trumpets and horns at the same moment; they will all raise their left feet at exactly the same instant, just as if they were but one company.

So far as the capabilities of the telharmonium are concerned, it may be stated that the New York installation is able to supply ten thousan-d subscribers, or more, with music of moderate volume at widely remote places. The very remarkable and rapid development of the invention has been thus eloquently set forth by Prof. A. S. McAllister in an article published in the Electrical World :

“From Hero, who first proposed to utilize the motive power of steam, to Watt’s first successful engine, was almost two thousand years. And between the proposal of Hero and the accGmplishment of Watt many inventors in different countries made ineffective attempts to attain the goal desired. From Huyghens’s proposal of an explosive motor to Otto’s successful machine two centuries elapsed, with scores of patents in the different countries of Europe. So from Sir Humphry Davy’s experimental arc to the Brush and Edison arc lighting machines” three-quarters of a century elapsed, during which scores of inventors in different countries endeavored to solve the problem in vain. Similar remarks apply to the progress of most great inventions, electri· cal and mechanical. But the process of producing music from dynamos has been carried from the first conception to the successful working machine by one man-Thaddeus Cahill-in a few years. And when one hears the plant at Thirty-ninth Street and Broadway, with its musical tones already equaling, if not surpassing, the instruments of the orchestra, one wonders what cannot be expected in a few years to come when the inventor will have had time to do his best, and when his work in all its details will be known ·to the world and open to improvement by others, and when musicians will have learned to use the new powers which electricity is placing at their command. Clearly the world has, through the wonderful powers of the electrical forces and the skillful use made of them by Dr. Cahill, a new music, a music which can be produced in many thousand places simultaneously, and which in its very infancy seems destined to surpass in sympathy and responsiveness-in artistic worth-the existing music of pipe and string, the evolution of many centuries.”

From ‘Scientific American’ vol 96 #10 9th March 1907

The reasons for the instruments vast proportions were that it produced sounds using ‘rheotome’ tone wheels; basically a set of  varied shaped rotors which when spun created tones through interrupted contact with wire brushes. Each key had it’s own rotor shaped to produce a set of harmonic overtones. The first version of the Telharmonium required a massive four hundred and eight dynamos, each weighing many tons. (this was reduced in later models where overtones from multiple rotors were ‘overlapped’ and rheotomes were replaced with alternating current dynamos in later models).

A single tone wheel generator
A single tone wheel generator

Essentially there were three version of the instrument. The first fully completed model, built in Washington DC in 1906 and moved to Cahill’s workshop at Holyoke, Massachusetts. The second, smaller (Fourteen feet and 14,000 lbs in weight)  machine was built at the Cabot St Mill in Hollyoke .The final machine, installed at Telharmonic Hall in New York  in 1917, was by then already obsolete, killed off by the far more efficient and cheaper vacuum tube, loudspeaker and radio technology.

The keyboard control of the Telharmonium at Telharmonic Hall 1907
The dual keyboard control of the Telharmonium at Telharmonic Hall 1907


The Telharmonium was essentially a collection of 145 modified dynamos employing a number of specially geared shafts and associated inductors to produce alternating currents of different audio frequencies. These signals were controlled by a multiple set of polyphonic velocity sensitive keyboards ( of seven octaves, 36 notes per octave tunable to frequencies between 40-4000Hz) and associated banks of controls.The resulting sound was audible via acoustic horns built from piano soundboards in the early models, later models were linked directly to the telephone network or to a series of telephone receivers fitted with special acoustic horns – this was the only way to amplify the sound in this pre-amplifier era (Cahill’s invention had pre-dated the invention of amplifiers by 20 years). The Telharmonium supplied 1 amp of power to each telephone receiver on the network this was much more than the telephone itself but was enough to be able to hear the music without lifting the receiver speaker to the ear however this also masked and disrupted any other signal on the line. The instrument was usually played by two musicians (4 hands) and reproduced “respectable” music of the time: Bach, Chopin, Grieg, Rossinni etc.

The 60ft long, 200 ton, $200,000 “Telharmonium III”
The 60ft long, 200 ton, $200,000 “Telharmonium III”

The sound produced from the Telharmonium at Telharmonic Hall was dogged with technical imperfections on behalf of the performers and by cable transmission errors such as sudden drops in volume when extra voices were added and a ‘growling’ effect on the bass notes that was said to make the overall experience ‘highly irritating’. Cahill completed the third and final Telharmonium in march 1911, this machine was even bigger and more expensive than its predecessor. The third Telharmonium had a whole set of redesigned and more powerful alternators, stronger magnets to reduce the bass rumbling and volume controls. The instrument was installed at 535 west 56th street New York City.

Inside the Telharmonium:

Tone Mixers from the Telharmonium III
Tone Mixers from the Telharmonium III
Dynamo tone generators at  Cabot Street Mill.
Dynamo tone generators at Cabot Street Mill.
Dynamos of the Telhamronium III in the basement of the Telharmonic Hall
Dynamos of the Telhamronium III in the basement of the Telharmonic Hall


Tone mixer
Tone mixer
Wiring looms of the Telharmonium III
Wiring looms of the Telharmonium III

Cahill and the ‘New England Electric Music Company’ funded a plan to transmit ‘Telharmony’ using the Telharmonium to hotels, restaurants,theatres and private homes via the telephone network. This visionary quest failed when the capital outlay became prohibitive and it was discovered that the machine interfered seriously with local telephone calls. The venture ground to a halt before the first world war. Rumour has it that a New York businessman, infuriated by the constant network interference, broke into the building where the Telharmonium was housed and destroyed it, throwing pieces of machinery into the Hudson river below. The final Telharmonium (the last of 3 built) was operating until 1916 and having survived the Wall Street crash and World War 1 was finally killed off by the advent of popular radio broadcasting and amplification.

Despite its final demise, the Telharmonium triggered the birth of electronic music- The Italian Composer and intellectual Ferruccio Busoni inspired by the machine at the height of its popularity was moved to write his “Sketch of a New Aesthetic of Music” (1907) which in turn became the clarion call and inspiration for the new generation of electronic composers such as Edgard Varèse and Luigi Rusolo.

No recordings of the Telharmonium/Dynamophone are known to have survived, though Arthur.T. Cahill, brother of Thaddeus, was as recently as 1950 trying to find a home for the prototype instrument, his search proved unsuccessful and the historic machine vanished. The principles underlying the Telharmonium are still used in the Hammond organ designed in the early 1930s.

Mark Twain (Clemens) remembers the Telharmonium:

“I recall two pleasant social events of that winter: one a little party given at the Clemenses’ home on New-Year’s Eve, with charades and storytelling and music. It was the music feature of this party that was distinctive; it was supplied by wire through an invention known as the telharmonium which, it was believed, would revolutionise musical entertainment in such places as hotels, and to some extent in private houses. The music came over the regular telephone wire, and was delivered through a series of horns or megaphones — similar to those used for phonographs — the playing being done, meanwhile, by skilled performers at the central station. Just why the telharmonium has not made good its promises of popularity I do not know. Clemens was filled with enthusiasm over the idea. He made a speech a little before midnight, in which he told how he had generally been enthusiastic about inventions which had turned out more or less well in about equal proportions. He did not dwell on the failures, but he told how he had been the first to use a typewriter for manuscript work; how he had been one of the earliest users of the fountain- pen; how he had installed the first telephone ever used in a private house, and how the audience now would have a demonstration of the first telharmonium music so employed. It was just about the stroke of midnight when he finished, and a moment later the horns began to play chimes and “Auld Lang Syne” and “America”.”Mark Twain: A Biography,Albert Bigelow Paine (New York: Harper & Brothers, 1912), 1364-1365

Patent Documents


MAGIC MUSIC FROM THE TELHARMONIUM Reynold Weidenaar Scarecrow Press 800/642-6420; 301/459-3366
Holmes, Thomas B. Electronic and Experimental Music. New York: Scribner, 1985. pp. 32-41

2 thoughts on “The ‘Telharmonium’ or ‘Dynamophone’ Thaddeus Cahill, USA 1897”

  1. Under Hammond, you say the Tellharmonium was of 1900, but it’s 1897–and on your left menu that makes it hard to find. (I posted a similar note on the Hammond spot, though I assume they all go to your same place.)

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