Brilliant_ The Evolution of Artificial Light - Jane Brox [25]
Murdoch lit his own cottage for his initial experiment, and then in 1802 he built a larger system for Boulton and Watt's forge in their Soho, Birmingham, factory. Its success led him to expand the system to include the workshops in Soho. In 1805 he began construction of a gaslight system for the Phillips & Lee cotton mill in Manchester, which he completed several years later:
It was estimated that more than 900 burners produced light equivalent to 2500 tallow candles burning on average for 2 hours on each working day. The factory contained eleven gasometers, six retorts, and more than two miles of pipes. Total expenditure on the plant was in excess of £5000, the cost of gas was about £600, allowing for depreciation of the equipment and the sale of the coke manufactured as a by-product.... The equivalent light produced by tallow candles would have cost an estimated £2000 a year.
These very first gaslight systems probably didn't significantly improve the quality of light in the workrooms. Most observers of the time claimed that one gas burner gave a light three to six times brighter than a common oil lamp, but they had no accurate way of measuring the difference, only a comparison of shadows, which at the time was explained this way:
Suppose it were required to know how many candles, of a given size, were equal to a patent [Argand] lamp:—place the lamp at one end of the mantle-piece [sic], and the candles at the other; hold up the snuffer-tray, a book, or any other object of which the shadow can be received on a sheet of white paper against the opposite wall; the object must be held in a line with the middle of the mantelpiece: the lamp will produce one shadow and the candles another; when the shadows are equally dark the lights are equal; the darkest shadow will be produced by the strongest light.
To its advantage, a gas flame could be larger than an oil lamp's because it wasn't restricted by the size of the wick, and under ideal circumstances coal gas's combustion was almost complete: it burned with a whiter, clearer flame (in contrast to the reddish orange glow of most simple oil lamps and candles). Yet in the beginning, gaslight was far from perfect. There were few filters for the coal gas, which contained both hydrogen sulfide and carbonic acid, so a foul smell accompanied the light. (Although Murdoch's system for Phillips & Lee filtered the gas through lime, which absorbed the hydrogen sulfide and carbonic acid, this did not entirely purify it.) The gas itself was of uneven quality, its delivery was unreliable, and the equipment was crude. As William O'Dea notes, "The burners were simply iron tubes with holes pierced in them; and apart from the variable and often poor illuminating quality of [the] gas produced ... the burners quickly corroded and, even when new, over-cooled the flame." Still, the jets didn't require individual attention, and there was nothing to spill or tip. And although gas left a sooty residue, it was cleaner, too.
If gaslight was cleaner, the grime of getting the coal to produce it rivaled that of the hunt for whale oil, as a descent into any British coal mine in the early 1800s would attest. According to a writer of the time,
Clean and orderly [the miners] coolley [sic] precipitate themselves into a black, smoking, and bottomless-looking crater, where you would think it almost impossible human lungs could play, or blood dance through the heart. At nearly the same moment you see others coming up, as jetty as the object of the search, drenched and tired. I have stood in a dark night, near the mouth of a pit, lighted by a suspended grate, filled with flaring coals ... the pit emitting a smoke as dense as the chimney of a steam-engine; the men, with their sooty and grimy faces ... their sparkling eyes.
Except for that suspended grate