A Wells light was a large paraffin-fuelled (kerosene) blowlamp used for engineering work, particularly for illumination, in Victorian times. At a time before widespread electrical lighting, they were the most common form of high-powered portable illumination used for construction work, particularly railways, civil engineering, shipyards and ironworks.
The Wells light was a typical blowlamp in principle, consisting of a floor-standing fuel tank with the burner on a tall post above it. It was distinguished by its large size, the more common plumber's blow lamp being a hand-held tool of about a pint in capacity. Wells lights were made in a number of sizes, the smallest Nº1 being of 800 candlepower with a 15 inch flame. Weighing 75 pounds (34 kg) when filled, it was advertised as "can be carried by a boy". The largest Nº3 produced 2,000 candlepower, weighed 240 lbs, and was available with barrow wheels for portability.
The burner of the Wells light used a vaporiser that heated the oil before it escaped the nozzle, so vaporising immediately. As the lamp was intended for use with heavy, sooty oils as well, this vaporiser was constructed of a square frame of straight tubes. Each tube was closed with a screwed plug that could be removed for cleaning. For initial lighting, the vaporiser would be preheating by burning a little oil in a tray beneath the burner. The burners were mounted horizontally, although some models were produced with a flexible hose to the burner that allowed it to be rotated vertically.
Pressure was provided by a hand-worked stirrup pump on the tank. Once pressurised, a large lamp could burn for some hours before the pressure fell enough to require more pumping. A particular feature of the Wells design was that the tank could be refilled whilst the lamp was still burning (i.e. without releasing the pressure in the tank) by using this same pressurisation pump as a fuel pump to suck in oil from another container.
The major use of the Wells light was for the illumination of outdoor construction work. They were portable and simple to operate. Their fuel was cheap and commonly available, especially as the Wells' pressure burner could burn a much lower and cheaper grade of oil than the lamp paraffin that was pure enough to not clog a wick lamp. Oil fuels were still more expensive than coal gas though, so fixed lighting, such as in factories, remained on town mains gas.