Only within the present century has gas superseded in London the dim oil lamps. About forty years ago, oil lamps and lighted candles were used in our churches and chapels; in some places of worship evening services were dispensed with altogether. A humorous anecdote is related of Dr. Johnson: it is said, one evening, from the window of his house in Bolt Court, he observed the parish lamplighter ascend a ladder to light one of the small oil lamps. He had scarcely descended the ladder half-way when the flame expired. Quickly returning he lifted the cover of the lamp partially and thrusting the end of his torch beneath it, the flame instantly communicated to the wick by the thick vapour which issued from it. "Ah!" exclaimed the Doctor, "one of these days the streets of London will be lighted by smoke."--_Notes and Queries_, No. 127. Certain scientific men were incredulous as to the practicability of lighting up the whole of London with gas, and Sir Humphrey Davey asked if it were intended to take the dome of St. Paul's for a gasometer! In 1820 gas meters were patented by John Malan, in 1830 by Samuel Clegg, in 1838 by Nathan Defries and others. Mr. Daniel Pollock, father of the late Chief Baron, was governor of the first "chartered" gas company in 1812. In 1822 St. James' Park was first lighted with gas. In 1825, its safety had not then been established on the part of the Government, a committee of the most eminent scientific men immediately inspected the Gas Works, and reported that the occasional superintendence of all the Works was necessary. However, since then so rapidly has the invention of gas-lighting progressed, that now in the present year of grace, there is neither City nor town in Great Britain of any note but what is illuminated with gas and has works for its manufacture in close proximity to the houses of its inhabitants. Gas supply of London, receipts for the year 1872, £2,133,600, for 1873, £2,544,000. What is coke? Coke is the residual carbon of pit coal after the volatile matters have been expelled by heat, it has a porous texture and a lustre sometimes approaching the metallic. It is a valuable fuel, producing an intense and steady heat and leaving but little residue after combustion. The residual coke in retorts has a quantity of ash, which, besides its earthy base of silicate, usually contains sulphur and other deleterious matter. The breeze can be used in furnaces and in burning bricks. There is a considerable quantity of pure hydrogen produced by the decomposition of water in cooling coke. Attempts have been made to manufacture gas from other substances besides coal--oil, resin, peat, and even water having in their turn commanded capital for a fair trial of their merits of all these; however, coal has alone stood the test of commercial success, those companies formed for other schemes having either been dissolved or become converts to its superior advantages. No doubt it will be considered Utopian--Mr.