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Dr Katie Cooper, Te Papa's Curator New Zealand Histories and Cultures

As the evenings draw out and the weather gets warmer, many of us start looking forward to long summer days of picnics on the beach, camping trips, walks in the bush and dips in the river. We’ll probably want a cuppa while we’re out adventuring and, luckily, in 1929 a New Zealander named John Ashley Hart (1887-1964) invented just the thing for boiling water on the go.

Hart was an electrical engineer and according to his granddaughter Annalee, he was also something of a ‘mad inventor’. He was awarded 32 patents in his lifetime, although the Thermette, patented in 1931, was by far his most enduring invention. Hart formed a company called HARCO Sales to promote and sell his portable boiler, and in the 1930s he would drive around Auckland with a huge sign on the side of his car.

The more wind the quicker it boils
Vintage car displaying a thermette advertisement
John Hart promoting the Thermette, 1930s. Courtesy of the Hart family

A Thermette is a cone shaped chimney surrounded by a metal cylinder that holds water. The chimney is open at the bottom, so a small fire can be set at the base using any type of fuel – paper, twigs, rubbish, whatever is available. The design of the chimney draws in air, which makes it burn more fiercely and thus boil water more rapidly. Depending on the type of fuel used and the amount of wind, it can boil enough water for 12 cups of tea in between 5 and 8 minutes.

The era of the Benghazi boiler

When World War Two broke out, Hart was asked if he would waive the patent for the Thermette so the New Zealand Army could make their own. Hart, who had served in World War One, agreed, and the boilers were issued to mobile units in North Africa. They were nicknamed ‘Benghazi Boilers’ after the port city in Libya where New Zealanders fought in 1942 and 1943. Apparently, the round scorch marks left in the earth by the boilers became calling cards of the New Zealand Army.

Generations of Kiwis have fond memories of using their Thermettes, particularly during road trips. As historian Jock Phillips points out, the Thermette came into its own at a time when cars were becoming more popular in New Zealand. They were too bulky to carry in a tramping pack, but perfect to stash in the boot of a vehicle. In fact, a 1938 advertisement suggested that ‘a Thermette is indispensable if you wish to obtain the full benefit from your car’.

To this day, you can still buy New Zealand-made Thermettes through camping and outdoor equipment stores. There are at least two regional Thermette societies – in Marlborough and Karamea – where members meet up to share cuppas, yarns, and the joy of being outside.

With thanks to the Hart whānau for reviewing this article and sharing unpublished research notes on their family history.

References

Bridges, Jon, and David Downs, No 8 Wire: The Best of Kiwi Ingenuity, Hodder Moa Beckett Publishers Ltd, Auckland, 2000, p. 32-33.

Hart, Annalee, interviewed by Jock Phillips, National Treasures television show, Season 1, Episode 1, 8 minutes, 55 seconds, https://www.tvnz.co.nz/shows/national-treasures/episodes/s1-e1, accessed 1 November 2024.

Macbeth, Hamish, ‘Winter School Thermette Society’, Karamea Community website, https://karamea.nz/web/articles/winter_school_thermette_society, accessed 7 November 2024.

McEwan, Bill, interviewed by Jesse Mulligan, Radio New Zealand Afternoons, https://www.rnz.co.nz/national/programmes/afternoons/audio/2018815290/the-marlborough-thermette-society-on-their-gatherings, accessed 7 November 2024.

Phillips, Jock, A History of New Zealand in 100 Objects, Penguin, Auckland, 2022, p. 263-266.

Riley, Bob, Kiwi Ingenuity: A Book of New Zealand Ideas and Inventions, AIT Press, Auckland, 1995, p. 47.

Smythe, Michael, 'Industrial design - Teaching industrial design', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/en/zoomify/41838/thermette, accessed 31 October 2024.

Te Papa, ‘Thermette’ Collections Online, https://collections.tepapa.govt.nz/object/1653294, accessed 1 November 2024.

White, Tina, ‘The invention that launched a million cups of tea’, Manawatu Standard, https://www.stuff.co.nz/manawatu-standard/lifestyle/104910335/the-invention-that-launched-a-million-cups-of-tea, accessed 1 November 2024.