During the nineteenth century a number of inventions were developed that used the opportunities afforded when the flow of a motion was momentarily stopped. These included the rotary sewing machine, the Gatling gun, the typewriter, and chronophotographic devices. Various iterations of this principle were also used to capture photographic images in ways that lent themselves to resynthesis including projection. There were a great many variations on this theme of taking and viewing images so that they appear to recreate movement – many of which continued well into the twentieth century. The technological arrangement that currently enjoys most interest (because it used a continuous strip of material, was used to project images and schematically resembled the technology of an institutional mode of reception called cinema during the 20th century) falls under the generally accepted rubric of cinematographe. It is worth being a little pedantic over this because the tendency to conflate quite distinct terms in understanding technology sometimes matters.

This is one of the key issues in Endless Intervals which undoes the entanglement of digital and electronic. Jeffrey West Kirkwood revisits the prehistory of what we now call “the digital” to remind us that the division of a flow to produce a sign did not start somewhere in the mid twentieth century but has a history that precedes even the controlled use of electricity as an energy source and a resonance that extends beyond technology to how the work of the mind has been understood. In this, the book follows Hugo Munsterberg, a prolific writer and strenuous advocate of the public engagement with science who drew a connection between cinematic form and the psyche. More exactly, the way that narrative strategies imported from literature, theatre, and film and moving image technologies were used in the cinema developed conventions that seemed to make explicit some ideas of how human cognition worked. Quite what the causal link was between these conventions – if there was one – is not a primary concern of film criticism at the beginning of the 20th century when Munsterberg was active. What was important however, was how a particular theory of human psychology was made apparent in productions for the cinema at the time.

Endless Intervals makes a considerable effort to link the connection between what it calls early cinema and period psychology with a very well-informed account of the various players and moves in European theories of psychology, in particular the role of instrumental experimental psychology and the struggles at the time in Germany. It is a fascinating and intricately woven story that makes its case within it own terms but is not entirely convincing in that while it pains to use precise language in some areas and in others it less precise as, for example. Film, cinema, and the cinematographe become interchangeable at moments when it matters. Similarly, the invocation of early cinema which may be a reasonable academic and publishing category makes no sense in a context that predates the cinema as an institutional form of reception that developed its own modes of production and film form to maximise profits. Cinema is quite distinct from many other affordances of the technology that were also developing as products including things called, topicals, topographics, instrumental film, educational film, surveillance film, and of course narrow-gauge cinematography. Narrow gauge film became a dominant format for the amateur film maker and the ‘home movie’ industry which persists today and vastly exceeds the ‘footage’ of mainstream cinema in the circuits of the estimated 15 billion mobile phones in use in 2021. Moreover, early cinema was a term that did not exist for people like Munsterberg and only took off in the late 1970s when material that was not widely available was released by the archives and ignited new interest in a form of film making that was unfamiliar and dismissed as primitive. It is estimated that through neglect, fire, and wilful destruction by the studios only about 5% of the films made up until to 1928 survive. Post 1978 the archives became more aware of the significance of their holdings, and as the corpus of material available to inform the history of film and the history of cinema has expanded and access to it has become ubiquitous through computerized digitisation the term cannot really sustain any historical credibility without a precise definition. The reductive analysis of the material available to film historians in the mid twentieth century, while invaluable at the time and a way of periodisation (for example as in the famous ‘cinema of attractions/ narrative integration’ story), has been overtaken by more informed and nuanced accounts. Drawing a parallel between a well-documented discourse on human psychology and such a slender body of evidence as typical becomes something of stretch.

The idea behind Endless Intervals is rich and fascinating. Its great strength is that it offers a rich insight into the politics of the mind in Germany in the late nineteenth and early twentieth century. The assumptions that drive the book are also worth exploring and recovering the work and reputation of Hugo Munsterberg is long overdue – he simply fell from the academic fashion in the academic arm wrestling between nations for the most ideological useful explanation of consciousness. There is fascinating work to be done here and case for the particularity of the arresting of flow as the core of meaning would be more convincing with greater precision. Not least in the discussion of flicker in the projected image which, as much of the period technical literature reveals, was not something that needed to be completely eliminated but actually was subtly retained and combined with other instabilities of the film frame (e.g., weaving) to give the satisfactory appearance of movement in the darkened space of collective viewing that the cinema eventually offered. A quality that in some digital products used in cinemas today, on laptops and phones is either compensated for in the flattening of the image or is coded into the programme to produce it artificially. Endless Intervals sets the panoply of inventions related to film and cinema technology as a paradigmatic fusion of science and art and is a valuable intervention to encourage more studies of film and cinema histories that recognise the impotence of history of film form and film aesthetics as evidence of interdisciplinary collaboration.