Progress of the arts.--Influence of it upon the morals and condition of man.--Beneficial tendency of chemical and mechanical improvements. --State of pre-eminence of people with regard to civilization.--How to be estimated.--Flourishing state of those nations which have shown the greatest activity in cultivating the useful arts, and establishing useful enterprises.--General observations on this subject.--Extra- ordinary discoveries of modern times.--New art of procuring light.-- Object of the treatise. PART I. PRODUCTION OF ARTIFICIAL LIGHT, &c. 8. Production of the flame generated during the combustion of certain bodies.--Characters of flame when perfect.--Most luminous flame, how produced with the least consumption of combustible matter.--Conditions necessary for that purpose.--Importance of this subject, with regard to the production and supply of artificial light.--The flame of bodies may be tinged.--Blue flame, red flame, green flame, &c.--Opinion concerning the origin of light emitted by bodies burning with flame.-- Philosophy of the subject.--Theory of the action of the instruments of illumination.--Rude method of procuring light employed in some countries.--Chemical action of candles, and lamps.--Agency of the tallow, oil, &c.--Office of the wick.--Reason why tallow candles require snuffing, and wax candles snuff themselves--Further observations on the subject. METHOD OF ASCERTAINING THE ILLUMINATING POWER OF CANDLES, LAMPS, AND OTHER LUMINOUS BODIES. 22. Optical principle assumed as law for determining the relative strength of lights of different kinds.--Admeasurement of the intensities of light.--Quantity of wax, tallow, oil, &c. requisite for producing a light of a certain strength.--Method of increasing the light of tallow candles, and to obviate the necessity of snuffing them.--A tallow candle placed in an inclined position gives more light than when placed perpendicularly and snuffed with an instrument.--Explanation of the fact.--Further observations on this subject.--Comparative cost of the light obtained by burning tallow candles of different sorts and sizes. PART II. GAS-LIGHT. 47. Encouragement given by the legislature to the new system of procuring light.--Gas-light company, incorporated by charter, to apply the new art of illumination by way of experiment, on a large scale, to illuminate the streets and houses of the metropolis.--Power and authorities granted to this corporate body.--are very restricted, and do not prevent other individuals from entering into competition with them.--Boundaries of their experiments.--limit of capital employed by them.--Power of His Majesty with regard to the gas-light charter.