Since the invention of the internal-combustion engine, mazut has been introduced directly into the furnaces of great ships. The heating power of this formerly despised product is almost double that of coal: 1 kilogramme of liquid fuel produces the same results as 1.7 kilogrammes of coal. Its use allows of the reduction by five-eighths in bunker space, and by 70 to 80 per cent. of the stokers, since a single man can look after several boilers. The fuelling of a ship is effected cleanly and quietly in a few hours. Hundreds of tons of oil can be pumped into the cisterns in a negligible time, and that even out at sea and in heavy weather. To give an idea of the difference in time and labour required for the loading of coal and oil before the sailing of a mail steamer of the tonnage of the _Olympic_ or the _Lusitania_, I will quote the following figures:-- Coal 5 days 500 men Oil 12 hours 12 men The labour of stoking and clearing the furnaces is done away with; there is no longer either dust or smoke. Parts of the ship which are too restricted or too inconveniently placed for housing coal can be used for oil. It is stored in the double bottom of the boat, and by utilizing the coal bunkers for general cargo the available storage space is increased by 10 per cent. On the latest _Cunard_ and _White Star_ liners the economy of space thus realized has been as much as 33 per cent. And Admiral Lord Fisher drew attention to the fact that on the _Mauretania_--the sister ship to the _Lusitania_--the adoption of oil fuel allowed of the reduction of the crew by three hundred men. The efficiency of a boiler heated by coal is not much more than 60 per cent.; that of one heated by oil reaches 80 per cent. On Japanese steamers of the type of the _Temyo Maru_, of 21,000 tons, with Parsons turbines of 20,000 horse-power, the consumption of oil is only 455 grammes to one effective horse-power, instead of 685 grammes of coal. The flexibility and ease of control are extraordinary.