With respect to the use of the fuel oil direct under pressure, this system generally involves the heating of the fuel oil, as well as its filtration, the fuel being supplied under pressure by means of pumps. The system is extensively employed at the present time on marine boilers operating with forced or induced draught, and, in this connection, the Wallsend system stands pre-eminent. Since writing the first edition of this little volume considerable advance has been made in connection with the use of oil fuel for general power-raising purposes, and much of this expansion has been consequent upon the introduction of a new burner--the “Scarab”--which is here illustrated. It is the invention of Lieut.-Col. Macdonald, and is the outcome of the war. When the Lieut.-Colonel was on service in Mesopotamia, he recognized the possibilities of oil fuel, for while wood and coal were being transported from India at great cost, oil was running to waste on the neighbouring fields of the Anglo Persian Oil Company. The Lieut.-Colonel therefore introduced a method of cooking by oil fuel, and immediately on his return to England he carried out experiments which led to the introduction of the “Scarab” burner. It is a simple contrivance, and is practically fool-proof, since there are really no parts to get out of order. The oil fuel flows through a tube by gravity, while another tube carries air compressed to about 10 lbs. pressure. The oil and air meet some inches distant from the mouth of the burner, and the combustion of the fuel, which is turned into a finely atomised spray, is complete. Experiments have been made with the burner for domestic purposes, and it has been adopted already in several London hotels for cooking purposes, though its general application is practically unlimited. CHAPTER VII PETROLEUM AS A LIGHTING AND COOKING AGENT From times immemorial, petroleum has been utilized as a lighting agent. Fifteen hundred years ago we have records of its use in the Far Eastern countries, and in the seventh century one of the Emperors of Japan ordered that his temples should be illuminated by the sacred oil light. And from that long distant date to the present times, petroleum has played a not insignificant part in the provision of artificial light throughout the world. For centuries, petroleum, as a means of artificial light, had the field to itself, and, though the Ancients consumed large quantities for lighting purposes, the apparatus used for burning the oil were of a most primitive type, giving results which to-day would be considered far from satisfactory.