Miller used to manufacture Airco Welding power sources when Airco was still selling... BOC (British Oxygen Corporation) also made Airco welders too...  AIRCO = Air Reduction Company
In 1904 Oscar Kjellberg in Sweden (Photo Right), the founder of ESAB, invented and patented the covered electrode... This electric welding process made excellent quality, strong welds very fast... ESAB became a world leading enterprise supplying welding equipment, filler materials and welding technology... They purchased AIRCO's electric welding equipment business and in 1989 Linde's (subsequently renamed Praxair) former welding equipment and filler metals  business which had become a separate company, L-TEC... At the same time they purchased the leading US innovator of flux cored wire and low hydrogen stick electrodes, Alloy Rods...

On November 16, 1916, a supplier of industrial gases, the Air Reduction Company (AIRCO) was officially formed and began producing and marketing high-purity oxygen and other industrial gases including acetylene... This company introduced a number of innovations in the welding industry, including MIG Welding... AIRCO sold their welding equipment business to ESAB in the 1980's, retaining the very profitable industrial gas business... The AIRCO gas business was later purchased by the British Oxygen Company and in 2006 that enterprise was purchased by Linde AG the German Company started by Carl von Linde...  At one time, Westinghouse was also manufacturing Airco welding power sources as well as other components too.

Respectfully,
Henry