of Phillips and Lee in 1805 he used a large retort of the form of a bucket with a cover on it.  Inside he installed a loose cage of grating to hold the coal.  When carbonization was complete the coke could be removed as a whole by extracting this cage.  This retort had a capacity of fifteen hundred pounds of coal.  He labored with mechanical details, varied the size and shape of the retorts, and experimented with different temperatures, with the result that he laid a solid foundation for coal-gas lighting.  For his achievements he is entitled to an honorable place among the torch-bearers of civilization.

The epochal feature of the development of gas-lighting is that here was a possibility for the first time of providing lighting as a public utility.  In the early years of the nineteenth century the foundation was laid for the great public-utility organizations of the present time.  Furthermore, gas-lighting was an improvement over candles and oil-lamps from the standpoints of convenience, safety, and cost.  The latter points are emphasized by Murdock in his paper presented before the Royal Society in 1808, in which he describes the first industrial installation of gas-lighting.  He used two types of burners, the Argand and the cockspur.  The former resembled the Argand lamp in some respects and the latter was a three-flame burner suggesting a fleur-de-lis.  In this installation there were 271 Argand burners and 636 cockspurs.  Each of the former “gave a light equal to that of four candles; and each of the latter, a light equal to two and a quarter of the same candles; making therefore the total of the gas light a little more than 2500 candles.”  The candle to which he refers was a mold candle “of six in the pound” and its light was considered a standard of luminous intensity when it was consuming tallow at the rate of 0.4 oz. (175 grains) per hour.  Thus the candle became very early a standard light-source and has persisted as such (with certain variations in the specifications) until the present time.  However, during recent years other standard light-sources have been devised.

According to Murdock, the yearly cost of gas-lighting in this initial case was 600 pounds sterling after allowing generously for interest on capital invested and depreciation of the apparatus.  The cost of furnishing the same amount of light by means of candles he computed to be 2000 pounds sterling.  This comparison was on the basis of an average of two hours of artificial lighting per day.  On the basis of three hours of artificial lighting per day, the relative cost of gas-and candle-lighting was about one to five.  Murdock was characteristically modest in discussing his achievements and his following statement should be read with the conditions of the year 1808 in mind: