Inside the Collection

Utility and beauty through science

Photograph of Level with compass, Tornaghi
Heliostat, Tornaghi, Sydney, Australia, c. 1887 H8086 Collection: Powerhouse Museum .

Do you know what a heliostat is? As with most scientific instruments, I had my educated guesses but didn’t know for sure. Luckily my colleagues are Matthew Connell and Nick Lomb and they can assist me in understanding my curiosities.

It comes up because the other night I was watching Better Homes and Gardens (I know, I’m awesome!) and two trends popped out at me that were very design and technology focused. One of them was a vertical garden, the other the use of heliostats, comprised of one or more mirrored surfaces for directional use of the sun in the shady (not sketchy!) bits of our back yards. I had seen both of these technologies used on a grander scale in Sydney’s Chippendale at the Central Park Mall and Apartment complex, which was also the episode’s inspiration. As it’s not too far from the Museum, I decided to go and have a closer look.

Photograph of Central Park heliostat & vertical garden
Central Park heliostat & vertical garden, George St Broadway. Image: Deborah Turnbull

As my gaze was drawn upward, I couldn’t help but be reminded of the idea of vertical gardens being de-constructed and displayed in the last Sydney Design, but I wondered at the use of heliostats. Traditionally, heliostats are used to track and redirect the sun’s light, for both luminosity and warmth. There is a portable, hand operated heliostat by A. Tornaghi (H8086) housed within the Powerhouse Museum collection used in surveying land rather then tending it. The design of the Tornaghi is descended from mathematician Carl Friedrich Gauss’ heliotrope (c.1817). The difference between the two seems to be that a helio­trope is an earlier model whereby the entire instrument is turned by hand to follow the sun to produce a concentrated beam of light on any desired target. A heliostat utilises a plane mirror to follow the sun’s beam across the sky so that the entire tool doesn’t need to move, only the plane mirror does. This later model featuring more automated functionality was driven by clockwork. This design can be seen on much larger scales as heliostats are most commonly used today in harvesting solar energy and are driven by computers and complex engineering, rather then operated by hand or clockwork.

Detail of a portable, hand operated heliostat
Detail of a portable, hand operated heliostat. H8086 made by A. Tornaghi, Sydney, and Collection: Powerhouse Museum.

Further research disclosed that the Central Park heliostat serves the traditional purpose by providing directional sunlight and warmth for the vertical gardens on the inner sides of the building, and for sunbathers who lay by the shaded pool. It also, of an evening, becomes a programmed artwork called Sea Mirror meant to mimic the waters of SydneyHarbour, by French project artist Yann Kersale.

Where our heliostat and Kersale’s are used for radically different reasons, their purpose, functionality and energy source remain similar. Whether surveying the land, providing sunlight where there is none for gardens and sunbathers, or functioning as a digital artwork, it seems that contemporary urban design is making use of both art and science for beauty and utility.

Written by Assistant curator, Deborah Turnbull

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