68 ENGINEERING PROGRESS IN THE U. S. NAVY. 



oil can be kept on hand are as easily established as are bases for coal, and 

 such oil bases would have, in case of danger of capture by an enemy, the addi- 

 tional advantage of being much more readily destroyed, together with their 

 stores of fuel, than are coal bases. 



The second disadvantage, that of excess cost over coal, is more than 

 compensated for by the quoted advantages. 



The third disadvantage, that of danger from fire, is very thoroughly 

 guarded against by storing the oil in compartments remote from the boiler 

 rooms, and situated well below the water-line of the vessel. In addition to 

 these primary precautions, additional safeguards are provided which render 

 the danger from fire fully as remote as the danger from magazine explosions. 



Upon deciding on the adoption of oil as a fuel for the naval service, the 

 Bureau of Steam Engineering examined carefully all the systems for burning 

 oil that now exist and finally decided upon that of mechanical atomization of 

 the oil as the one most suitable for naval use. 



In this system, the oil is pumped through heaters to the burners within 

 which it is given a whirling motion. The small central core of oil, discharg- 

 ing through the tip orifice with this whirling motion, the oil flies off and forms 

 a cone of fine mist. This oil mist mixes thoroughly in the furnace with air 

 which passes into the furnace through a cone register surrounding the burner, 

 the register having adjustable openings and guide vanes so that the amount 

 of air to each burner may be regulated and the direction of flow of this air be 

 slightly oblique to the axis of the cone of oil. 



The success of the system depends almost entirely upon the proper 

 handling of the air. Improper air regulation will produce a series of rapid 

 explosions of oil in the furnaces with consequent destruction of the brick 

 linings of the furnaces. With proper handling, the oil bums almost noise- 

 lessly, and the amount of smoke produced can be held absolutely under 

 control. 



In the first battleships fitted with oil fuel, the oil was only fitted as an 

 auxiliary fuel and was intended to be used as an aid in keeping up steam 

 when the coal should be so low as to be remote from the fire-rooms and so 

 require excessive trimming. The results obtained with this mixed system 

 are not to be rated as good nor were good results expected, as the furnace 

 volumes of coal-burning boilers are too small to permit efficient burning of 

 oil. Furthermore, when burning the oil and coal in combination it is impos- 

 sible to so regulate the air supply that each fuel will obtain the proper 

 amount. This results in excessive production of smoke and no increase in 

 steam production over coal alone. 



To illustrate the value of oil when used as the sole fuel as compared with 



