Before there was sound in movies there was smell. In 1906, a Pennsylvania movie theater soaked a wad of cotton wool in rose oil and placed it in front of a fan. When a newsreel about the Rose Bowl played, they turned on the fan and the smell of roses wafted over the theater. Audience complaints, technical difficulties, and the tendency of odors to linger on fabrics limited the success of such multisensory movie experiences, relegating Smell-O-Vision to the land of gimmicky failed technologies, an old fashioned vision of the future.

Looking through Hans Laube's patents for Smell-O-Vision and more recent technologies for delivering odors as part of an immersive multimedia experience, I was struck by the simple weirdness of smell as media. We're used to media that are transmitted through sight and sound, but smells are not just waves and photons, they are volatile molecules, chemicals in the air that are "broadcast" to the nose, transmitted very differently from the images and sound of the movie. Storing, emitting, targeting, and synchronizing smells with precise timepoints in a film requires vials, heaters, motors, fans, and maybe even masks, and the behavior of smells in a large space and how they reach the audience's noses is much harder to control than the pictures on the screen.

Shortly after the first (and last) release of a Smell-O-Vision movie, Scent of Mystery, where the murderer was revealed by the smell of his pipe tobacco, other engineers experimented with more individualized immersive media experiences. The Sensorama was Morton Heilig's vision of the "cinema of the future," showing a film of a ride on a motorbike with a vibrating and tilting seat, fans blowing wind in the viewer's face, and the aroma of flowers or baking pizza as the rider passes a garden or an Italian restaurant. However, like Smell-O-Vision before it, Sensorama failed to attract funding and is now merely a mechanical curiosity in the early history of virtual reality.

Smell was rarely part of virtual reality apparatuses, but a 1997 patent shows how fragrances could be incorporated into "virtual reality shows" or computer games to create a more fully realized and embodied sensory experience.

A later patent citing the virtual reality system imagines digital release of smells in an immersive device for therapeutic purposes:

These virtual reality systems require encoding scents as digital information, bits that must be converted to the atoms of odor molecules that will travel through the helmet's tubes. Digitally sensing, encoding, and "compressing" chemical data, from the millions that could be present in the air, to the thousands that we can smell, to the few that are the primary factors that influence a scent is an extremely difficult problem. Technologies that allow computers to sense and interpret smells have primarily focused on their application in industrial food production, medicine, and environmental sensing, but some researchers are using these methods to develop tools for digitally transmitting odor information, to make a "Smell-O-Internet".

The "resolution" of smell information in these these multi-sensory media experiences has gone from the single smell of rose oil in 1906 to about a dozen smells in 1960's analog Smell-O-Vision, to approximately 100 "primary" smells that engineers hope can be mixed to make many more complex scents in digital products like iSmell from the early 2000's.

Even as the technology improves the weirdness of smell remains, and the social reality of odors keeps the technology at the fringes. It might be nice to smell a scene of baking cookies or a photograph of a strawberry, but do we really want to smell the internet?