I have given a description of the apparatus and machinery by means of which the coal-gas is prepared, and the methods employed for distributing and applying it as a substitute for candles and lamps to illuminate houses, streets and manufactories;--I have furnished the data for calculating the expense that must attend the application of this species of light under different circumstances, so as to determine the relative cost or value of gas-lights, when compared with the lights now in use--together with such other practical directions and facts as will enable the reader to form a proper estimate of the gas-light illumination, and to put this art into practice. I have stated the leading objects of public and private utility to which the new system of lighting may be successfully applied, candidly pointing out those in which it cannot be made use of to advantage. I have detailed the most obvious effects which the discovery of lighting with coal-gas must inevitably produce upon the arts and upon domestic economy; its primary advantages--its views--its limits, and the resources it presents to industry and public economy. I have endeavoured to show how far its application is safe, and in what respect it is entitled to public approbation and national encouragement. It may not be improper, before concluding, to inform the reader, that my qualifications for the task I have undertaken are founded upon many years experience, during which time, I possessed peculiar opportunities to witness and verify the most extended series of operations that ever have been made for the purpose of ascertaining the practicability, safety, and general nature of the art of applying coal-gas as a substitute for tallow and oil; and which have, as it were, fixed the fate of this art. The numerous experiments I instituted, upon a large scale, by desire of the Gas-Light Company, for the purpose of adducing them in my evidence before the House of Commons, and House of Lords, on a former occasion, have enabled me to collect such information as could not have been obtained by other means. The substance of these results (which are printed by order of Government,) are incorporated in this Treatise, together with such other facts and observations as have presented themselves in the routine of my profession elsewhere. To generalize the results of my observations, and to make them practically useful to the public, is the aim of the present publication, and I need scarcely add, that their suffrages to the zeal and industry, at least, with which I have endeavoured to attain my object, will be a source of infinite satisfaction. FREDRICK ACCUM Contents. INTRODUCTORY OBSERVATION. Page 1.