Warm words for a cool invention

Landing page image: an engineer demonstrates a Thermotank unit. Image: taken from book

'After writing a number of books concerned with the shipbuilding industry on Clydeside, I lamented the fact that virtually nothing appeared to have survived to put on record the achievements of the well-known engineering company, Thermotank Ltd.

'I had a personal connection with the company, as my father had worked there, and I recalled the name Thermotank being mentioned many times when I was a child. However, at this stage in the 21st century, it seemed that the Thermotank Company had simply disappeared without trace.'

These are the words of author Ian Johnston. He had encountered a common phenomenon in maritime, where mergers and acquisitions often lead to the extinguishing of past company names, but he was not going to let this put him off discovering more.

It turned out that Thermotank Ltd was a particularly difficult organisation to research, because its successor companies had not maintained its archives. Yet, as Johnston embarked on his mission of discovery, he did eventually find libraries and former employees who had kept information.

So what exactly was Thermotank? As Johnston finds out, it was nothing less than the first air conditioning system that could deliver both cooling and heating onboard ships. Invented by marine engineer Alexander Stewart around the turn of the 20th century and developed by the company he founded with his two brothers, the device was adopted by major shipping companies such as Cunard and White Star, and was later used in New York skyscrapers.

'In very simple terms,' Johnston explains, 'the Thermotank unit comprised a chamber containing numerous tubes which could either be filled with steam, cold water or brine to heat or cool the air circulating around the tubes in the chamber.

'Air from the atmosphere was drawn into the chamber and thus treated, was then forced into a network of trunks (ducting), using electric fans which delivered the air to whatever compartments were to be heated or cooled.'

If you are thinking that this sounds like a story for marine engineering nerds, then you'd be right, and there's nothing wrong with that. It's fascinating to read about a device and a company that were nearly lost to history, and the author makes a good job of bringing the past to life through potted biographies of key figures and the memories of Thermotank employees.

Illustrations are used very effectively, including a photograph in which Thermotank devices can be spotted next to the funnels of the Lusitania. There are also diagrams showing how the system was installed, and even reproductions of old brochures which a former employee saved from a skip.

Embrace your inner nerd and pick up a copy for your Christmas reading!

Blowing Hot and Cold: Thermotank and the story of air conditioning at sea
By Ian Johnston
Seaforth Publishing, £19.99
ISBN: 978 10361 07697