Hard soldering?
Are those kettles not 'decontructed' Samovars in fact?
Brilliant idea, to enclose the flame on all sides with well conducting metal. Very high efficiency coefficient.
I read somewhere the idea comes from the Nomads roaming the Asiatic plains. Dried goat and sheeps poo was used ( sparingly) to boil water in similar designs.
Just copied this from the Ghillie sight.
The chimney or volcano kettle design was refined by John Ashley Hart of New Zealand who may have been inspired by traditional Mongolian and Chinese hot-pots which had a central chimney. His "Thermette" kettle was first manufactured in 1929 and was standard issue for the New Zealand Army during World War II where it became known as the "Benghazi Boiler".
The George Marris & Co. of Birmingham, England began making iron bedsteads and brass/copper fern pots in the 1800's. Marris began diversifying into other products in about 1906, when the brand name "Sirram" (Marris spelled backwards) appeared first on their picnic sers.
There's a record of a meeting between one of the Marris family members and John Ashley Hart after which the first "Sirram Volcano Kettle" appeared. These early copper models carried an inscribed plate which included "Registered Design No 731794". The records of the British Public Records Office show that this design number was issued in 1928. So that gives us the earliest definitedate for the "Sirram Volcano Kettle". Marris eventually changed the production of the kettles from copper to spun aluminium.
We know that "Sirram Volcano Kettles" were still in production in the late 1960's as the book "Modern Camping 1968", by Jack Cox quotes a UK Consumers Association test of 21 camp stoves which concluded " for boiling water quickly or washing up, there is nothing to beat a Sirram Volcano Kettle, either at home or abroad". Production of the kettles ended around 1970 when the company was sold. Similar versions began to be produced by a number of companies, with some even claiming to be the original design.
I had spoken with Steve at Ghillie kettles before about the above before when I was trying to work out copyrights on the Mkettle when I was doing a group buy years ago