"The trouble with avant garde music is that it has lost its original meaning and now has as many rules and clichés as country or rock & roll. If in 50 years time they will look back at the early 1980s, or whenever, and say that was the new avant garde era, that event must be avoided if we are to remain true" - William Bennett (Whitehouse) 
Mechanical instruments of various sorts date back several centuries. Clockwork musical boxes and hand- cranked barrel organs both date back to the eighteenth century. One inventor of the period, Jacques Vaucanson, even produced a musical box with mechanical figures on it who actually went through the motions of playing real instruments. However, none of these developments lent themselves to the production of creative music.
Industrial music relied to a great extent on the use of electronic instrumentation, as well as on other technological innovations of the twentieth century such as tape recording. By the late seventies, this technology had long since passed from the province of academic composition into use by popular musicians, but with rare exceptions most rock-based artists made little attempt to really explore the technology's potential. For most pop bands, tape and electronic filters allowed them to clean up their sound, present an illusion of space or depth, and generally to ensure that very conventional music was shown in its best light. Where keyboards were used, they were most often employed like pianos or organs. In the eighties, the technology would become essential for most pop and rock music, but in the seventies, only pioneers like the dub producers, German cosmic bands, or Brian Eno, applied the lessons learnt by earlier avant-gardists to more accessible music.
The use of electricity to produce sound can be traced back at least to 1837, when Dr C.G. Page of Massachusetts reported his accidental discovery of "galvanic music", a method of generating a ringing tone using horseshoe magnets and a spiral of copper wire . At this time, however, nobody successfully applied the phenomenon to the production of an actual musical instrument. The first genuine electronic musical instrument is claimed to be Elisha Gray's "musical telegraph", invented in 1874 (a two-octave polyphonic electric organ), and many others followed; William Duddell's "singing arc" in 1899 and Thaddeus Cahill's telharmonium in 1900, for example. This latter instrument was an extremely complex device, weighing 200 tons and 60 feet long. Although the telharmonium was unsuccessful, the mechanical principles it used were later adopted by the Hammond organ (first built in 1929).
Commercial electronic instruments followed the development of the thermionic valve by Lee De Forest, and include the Theremin, the Ondes Martenot, the Sphärophon and the Trautonium, all of which were available in the 1920s. Adventurous composers such as Edgard Varèse, Darius Milhaud and Oliver Messiaen all wrote music for these instruments, seeing them as an opportunity to extend their sound vocabulary, but they amounted to little more than that. In addition, these instruments became quite popular in Variety and music hall performances, where as a source of particular amusement they were at least treated as more than just another orchestral instrument. In 1931, Leon Theremin produced a special keyboard for the American composer Henry Cowell, called the rhythmicon, which could produce repeating series of notes, and was probably the first ever sequencer. Cowell's book, New Musical Resources, had been published the previous year, documenting his search for new piano-based sounds, such as tone clusters, and effects produced by playing directly on the piano strings , and he remains one of the most important figures of the classical avant-garde in this century.
By 1942, John Cage was prophesising the future, writing "Many musicians have dreamed of compact technological boxes, inside which all audible sounds, including noise, would be ready to come forth at the command of the composer."  One of those was Edgard Varèse, who told one interviewer: "I myself would like, for expressing my personal conceptions, a completely new means of expression. A sound machine."  Varèse's historical significance is due to his realisation that music need not just be a series of notes and harmonies, but could consist of any form of "organised sound", and although he considered musique concrète "simple-minded", this was one of the important changes in musical philosophy that forms part of industrial music's prehistory.
It wasn't until shortly after the Second World War that composers really began to explore the potential of these new technologies as anything other than an adjunct to conventional orchestration. The significant event was the invention of the tape recorder.
The first magnetic recorder had been patented in 1898 by Danish inventor Valdemar Poulsen . His device used a microphone (itself dating back to Bell's 1876 experiments in telephony) to drive an electromagnet which altered the magnetic pattern on a coil of steel piano wire. Steel-based recorders were superseded in 1935, when plastic tape coated with a magnetic iron oxide was produced in Germany, and as commercial devices appeared after the war, their potential for use in creating new music soon became evident. Musique concrète was introduced to the world in 1948 by French sound engineer, Pierre Schaeffer. His first composition, Etude aux chemins de fer, used recordings of steam locomotives, an interesting thematic link to the obsessions with modern industry of the futurists and perhaps even to the imagery that the words "industrial music" erroneously evoke. This work actually used record players rather than tape, but allowed the collage of separate recordings, changes in speed, repeating grooves, and backwards recording. (Others had already experimented with the use of variable speed record players to create new music rather than just record it, including Edgard Varèse, Darius Milhaud, Paul Hindemith and John Cage). In 1950, collaborating with Pierre Henry, the Symphonie pour un homme seul was finished, again using record players, and representing a much more complex and powerful attempt to combine spoken voice, pre-recorded music, mechanical and natural sounds.
As with the use of electronics to generate sound, the techniques involved encouraged several musical revolutions. Initially, in the hands of trained composers, it provided access to sounds that had previously been unavailable to music. It also allowed these sounds to develop over time in ways unreproduceable by traditional players of instruments. Finally, it laid the seeds for the production of music by the musically untrained; it was no longer necessary to practice an instrument or learn to read music in order to produce worthwhile music. It would be some time however, before musicians outwith the classical avant-garde began to realise the possibilities inherent in tape recording that musique concrète explored.
Meanwhile in Cologne, Herbert Eimert, Robert Beyer and Werner Meyer-Eppler had founded the Studio for Electronic Music at Northwest German Radio. Their instrumentation was primitive, and it was only through the creativity and dedication of Karlheinz Stockhausen, who came to the studio in 1953, that their pure electronic music developed into something significant. Initially, the Cologne musicians concentrated only on electronically generated sound, but by the middle of the decade, the barriers between conventional instrumentation, electronic sounds, and manipulated tape recordings were broken, resulting in such seminal works as Stockhausen's Gesang der Jünglinge (1956) and Varèse's Poeme Electronique (1958).
By the end of the fifties, early synthesizers had been developed, notably the RCA Synthesizer best known through its use by American composer Milton Babbitt (throughout the fifties, the activity in Europe was paralleled by work in America, by composers such as John Cage, Otto Luening, Vladimir Ussachevsky, Gordon Mumma and Robert Ashley). The Moog and Buchla synthesizers of the late sixties continued a trend towards more flexible, more portable, less expensive instruments that allowed musicians outside the classical realm to apply the new technology and techniques to their own forms of music. Although much of the early electronic music had met with indignant and outraged audience reactions, the sixties saw a process of gradual popularisation occurring. Notable milestones along the way included Louis and Bebe Barron's electronic soundtrack to the film Forbidden Planet (1955), Frank Zappa's Freak Out (1966), The Beatles' Revolver (1966) and Sergeant Pepper's Lonely Hearts Club Band (1967), and Walter Carlos's Switched On Bach (1968).
The avant-garde musical tradition is fundamental to industrial music in terms of the techniques and type of music presented. Listening to almost any electronic or concrète composer from the 50s, 60s or 70s alongside industrial music by Zoviet France, the Hafler Trio, P16D4, Cranioclast, Strafe F.R. or Nurse With Wound, is an interesting experience. Not only are the techniques (electronic synthesis and processing, tape manipulation) identical, but the abstract nature of the sounds employed is too.
Luc Ferrari, who has been an active composer or musique concrète since 1958, stands apart from other similar composers in his reluctance to process natural sounds into unrecognisability, allowing the mental associations provoked by the sounds used to create a kind of narrative drama. Works like Petite symphonie pour un paysage de printemps (1973), or Hétérozygote (1964), share unmistakable similarities to the work that the Hafler Trio creates two decades later. Ferrari's earlier Visage V (1959) was notable for sharing the Futurists' taste for industrial (mechanical) sound, material which was also employed by Philippe Carson, in his dissonant Turmac (1962), and Luigi Nono in his political protest piece La fabbrica illuminata (1964). Ferrari's work is particularly interesting, because he showed clear awareness that musique concrète's real radical impact was to open avant-garde music up to the amateur, to the non-musician. "My intention was to pave the way for amateur concrète music, much as people take snapshots during vacations". 
Similarly, Bernard Parmegiani, one of the most prolific of concrète composers, shares much in common with abstract industrial musicians; not only did he have no formal musical education (other than childhood piano lessons), but as a result he adopted an intuitive, improvisatory approach to tape music, dispensing with scores and technical details in favour of a hands-on, intuitive approach. His works, such as La table des matières (1979) and De Natura Sonorum (1975), tend to adopt gradual, transformative shifts from one sound texture to another, a form that finds favour amongst such industrial groups as Zoviet France, P.G.R. or John Watermann.
What the composers of electronic music and musique concréte had done was to demolish the primacy of the score in "art" music. As Evan Eisenberg has written, "Suppose one wished to make music as directly as a painter paints. A painter would be outraged if he were asked to create a work by listing the coordinates of dots and the numbers of standard colours, which we could then interpret by connecting the dots and colouring by number. But that is what a composer is asked to do" . As will be shown below, Ferruccio Busoni was one of the first classical composers to dream of a way out of the straitjacket of score-writing, and Edgard Varèse's desire for the same freedom had caused him great frustration until tape music came along. From the beginning of the 1950s, the classical avant garde began to enjoy the freedom to create music like painters, intuitively.
The industrial musicians, although in many cases aware of this avant-garde tradition, owe a more direct debt to the fringes of rock music, notably groups like Tangerine Dream and Kraftwerk, who combined "serious" composers' fascination with new sounds with an interest in accessible rhythms. In Britain, which it's not unfair to name as the main home of industrial music, the only interest that fringe-rockers seemed to show in electronic instruments was as enhancement to a more conventional rock instrumental line-up (Hawkwind and the Beatles are two possible examples) or as a means of replicating the grandeur of classical music (ELP, Yes and far too many others). In the early seventies in Britain, there seemed to be little interest outside the classical community in genuinely seeing what kind of new music the technology would create.
Elsewhere the situation was different. In America, Frank Zappa's knowledge of classical avant-gardism had an enormous impact on his rock-based music, leading to mixtures of electronics and tape manipulation such as The Chrome Plated Megaphone of Destiny . Other psychedelic bands, such as United States of America, also adopted electronic instruments and elements of avant-garde techniques . Similarly, The Residents, from their beginnings in the early 1970s, created music that ignored and assaulted conventional notions of taste and quality, playing with tape technology and (on albums like Third Reich'n'Roll, a classic collage of sixties pop viewed through a very grimy lens) not only predating pop sampling controversy but doing a better job of it as well. In 1968, a New York duo called Silver Apples combined simplistic, machinelike electronic oscillators with psychedelic pop and pre-Can metronomic rhythms that foreshadowed the following decade's music from artists like Devo or Kraftwerk . If you trace a line back from industrial music through Kraftwerk, you'll find that Silver Apples are their oft-ignored true ancestors.
In Germany, artists like Tangerine Dream, Faust, Neu, Cluster, Klaus Schulze and Can (as well as many who never achieved quite such a level of fame) took the new, less expensive electronic instruments as a signal not for rock-based experimentation (which with groups elsewhere like Pink Floyd and Roxy Music was gaining more attention) but to create music that appropriated the ideas of the "serious" composers while stilling aiming at a popular audience. Can's Holger Czukay is one of the most obvious examples of how the technology (and the associated taste for musical experimentation) crossed from the elite to the popular. After studying with Stockhausen, Czukay and Irmin Schmidt took their ideas into the rock world, and Czukay's earlier experiments with tape collage can be heard on the Canaxis album. On their early albums, even bands who later moved towards tonality and clarity, like Tangerine Dream and Cluster, created music that thrived on noise, atonality and confusion.
Faust demonstrated most clearly an attitude of total freedom to explore and experiment, utilising every new technology and quite capable of embracing noise, collage and a rock rhythm within a single album, if not a single track. Although Can, as the most popular of these German groups, are the most often cited by more recent musicians, Faust and the others had the most important influence on industrial music, by demonstrating that experimentation didn't have to be inaccessible, and that the willingness to try things was more important than instrumental proficiency.
Kraftwerk's growing taste for a music that not only used the new technology but also stylistically mirrored their perception of that technology had resulted in two classic albums by the time Throbbing Gristle made their first recording; Radio-Activity and Trans Europe Express, both of which fashioned a clarity and beauty out of the sterile, repetitive sounds that electronic oscillators most readily produced. Having established a suitable aesthetic mirror for the developments that (at the time) had the greatest long-term impact on society, budding industrial musicians saw rhythmic electronic music as one of the essential elements in their own creations. Like Kraftwerk, they wanted to mirror their environment, but unlike Kraftwerk they were motivated by a comprehensively critical revulsion against that environment.
Surprisingly, throughout the seventies in Germany, there was little evidence that the avant-rock groups and the avant-garde composers could work on common territory. There are isolated examples of serious composers who gained more popular acceptance, such as Asmus Tietchens. He had started producing serious electronic music in 1965 , but it wasn't until 1980, when he briefly ventured into more accessible synthesizer-based realms, that he received any public recognition. Since then, he has collaborated with such industrial musicians as Merzbow and Arcane Device, without compromising his atonal concrète music. Tietchens' position is significant, as it shows how meaningless the distinction between "serious" composers and enthusiastic amateurs has become in the field of abstract electronic and tape-based composition. Perhaps industrial music's lasting significance will be recognised as its demolition of this outdated distinction.
In Britain, perhaps the most important artist to have any real influence on industrial music was one whose aesthetic was quite opposed to it; Brian Eno. Eno's time as an art student had introduced him to avant-garde music by the likes of LaMonte Young and Philip Glass, and he happily applied these influences to rock music, first as a member of Roxy Music and then on his own. (The album No Pussyfooting, recorded with Robert Fripp, is basically a guitar-based reworking of Pauline Oliveros' electronic composition I of IV, for example). Most importantly to the budding industrial musicians, his concentration on the use of the studio, and his insistence that he was a "non-musician" inspired many who had no formal musical training to try it for themselves.
Also important was the existence of the B.B.C. Radiophonic Workshop, Britain's equivalent of other institutionally-sponsored electronic studios such as the Northwest German Radio studio that Stockhausen used, or the Columbia-Princeton Electronic Music Center. Unlike earlier studios, which provided facilities for the abstract explorations of avant-garde composers, the Radiophonic Workshop had a more prosaic role producing soundtrack music and special effects for radio and television, and as a result its electronic works were heard by a much wider public . Like earlier associations between electronic music and science fiction entertainment, the public found it difficult to disentangle electronics and imagery of outer space, but the Radiophonic Workshop ensured that potential future industrial musicians were well aware of the potential of electronic sounds.
These threads don't just lead to industrial music of course. Bruce Gilbert and Graham Lewis (of rock band Wire) showed how the same musical influences as the industrial musicians weren't enough; they lacked the same drive to transgress and consequently their work as Dome (and under other names) is of more musical than cultural interest. Similarly, lacking any transgressive instinct whatsoever, there has been a very large number of artists who would take not just the technique of Eno, but also his limpid, passive style, combined in varying proportions with the spaced out attitude of the mostly-electronic "cosmic" musicians.
It's also important to point out that several bands who were categorised as "industrial" drew influences from much more popular music than others. Funk and disco, via artists like Defunkt, Donna Summer & Giorgio Moroder, Chic and James Brown, all fed into the anti-soul dance music of Cabaret Voltaire, ClockDVA, 23 Skidoo, Hula and others. With hindsight, it's easy to feel disappointed that the loose-limbed, less uptight dance music that inspired such early industrial groups was replaced by a funkless rigidity in later industrial dance outfits.
It took three decades for the technological revolution in music to truly make itself felt, as the new technology progressed first from the hands of the "establishment", and then from the hands of more conventional musicians, such as the rock virtuosos. Punk, when it came, was arguably less revolutionary; jazz, reggae and other genres had already introduced the independence that punk ideologues trumpeted so loudly, and for all punk's claim that it allowed people with no training or experience to pick up a guitar and get themselves heard, it still relied on an ability to learn basic chords; tape-recording and electronics have had a far more radical influence.