Now oil has considerable advantages over coal. Its extraction is remarkably easy compared with that of coal. What is the boring of a well and the installation of some simple machinery on the surface compared with the expensive subterranean workings which are involved in the exploitation of a coal-mine? An oil-boring before the War cost a few hundred thousand francs, while the simplest workings for a colliery always necessitated an expenditure of several millions. The installations once made, oil flows by itself into the reservoirs, whence it is conducted by pipe-lines to the sea-ports and there pumped into the ships. It may be refined before exportation or only on arrival in the country where it is to be consumed. The expenditure upon labour in these various operations is extremely small, especially in undeveloped countries where native labour is employed. Thus, even at the present time, in the Dutch Indies the coolies are paid a florin a day. Now at the end of the War the employés of the Royal Dutch in the Dutch Indies numbered only 1,000 Europeans and 2,906 natives and Chinese for a production of 1,706,675 tons. A native earned only 300 gold francs a year for 80 tons of oil extracted, refined and transported to the coast.
After the Bolshevik revolution wages at Grosny were still only seven roubles a day, which, considering the depreciation of Russian money, represented very little. Generally the expenses of production in Russia did not exceed a few kopecks a pood (50 kopecks for one of the best-known firms, that of Akverdoff).
Thus oil is bound to become in future more and more important as a fuel, because of its peculiarity in necessitating so insignificant a charge for labour—which protects it from the inconveniences resulting from the social crises in the midst of which we live—and because its net cost is so small. For half a century it was used only for lighting purposes, and then it had to compete with gas and electricity. At one time there was talk of limiting production!
Between 1900 and 1910 the invention of the internal-combustion engine and the enormous development of motoring gave it new impetus. Fine oils only had been used up to then. Under pressure of the demand, it became customary to raise and refine poorer and poorer oils, giving from 60 to 75 per cent. of waste products.
There remained the mazut[1] or fuel-oil, which required very high temperatures for combustion and which was very dirty in use.
Then the German, Diesel, invented the internal-combustion engine for heavy oil. The mazut, subjected to high pressure in a cylinder, produces an explosive mixture which, without sparking-plug or magneto, drives the pistons in the manner of a petrol engine. The installation is rather heavy, but no boiler is required, and it takes up much less space than a steam engine of the same power. A vessel fitted with a Diesel engine can sail for fifty-seven days without re-fuelling, while with a steam engine it could only sail for a fortnight. A ship fitted with a Diesel engine and having a speed of 20 knots could sail from France to Suez, India, Australia, New Zealand, and return by Cape Horn without re-fuelling. But, better than any words, the following little table, made out for two boats of the same power, will give an idea of the great advantages of the Diesel engine:—
| Diesel. | Steam. | |
| H.P. | 21,000 | 21,000 |
| Weight of engine and accessories | 1,000 tons | 3,400 tons |
| Space required | 5,300 cu. m. | 10,000 cu. m. |
| Daily consumption | 100 tons | 360 tons |
| (heavy oil) | (coal) | |
| Consumption for a voyage of 15 days | 1,500 tons | 5,400 tons |
| Bunker space for a voyage of 15 days | 1,700 cu. m. | 7,000 cu. m. |
| Total space required for engine and fuel | 7,000 cu. m. | 17,000 cu. m. |
At first oil was used on fishing boats, then on small coasters. To-day the biggest British cargo boats, of the type of the Zeelandia or Sutlandia, are fitted with Diesel engines. All German submarines had them during the War. In 1917 Herr Ballin,[2] the great friend of William II and the head of the Hamburg-Amerika line, just before his suicide decided on the construction of a fleet of enormous ships fitted with internal-combustion engines. Scandinavia, Holland, Italy, all now use the Diesel engine. France alone remains behind in this respect. It has even been used on railways, a little-known fact. Diesel locomotives with four cylinders, built by Sulzer Brothers of Winterthur, have recently been run on the line from Berlin to Mannsfeld.
"The development of our metallurgy," wrote Admiral Degouy in April 1920, "will soon give us the assurance that we also shall be able to manufacture large-bore cylinders and pistons of flawless casting, like those made in Augsburg, Nuremberg, Stockholm, and Christiania, which will support for long periods without change (and consequently without leakage) the temperature of 1,000° C. which is developed by the combustion of mazut in these engines."
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:—