HEAVY-OIL ENGINES FOR MARINE PROPULSION. 241 
at full power and a loss at the greatly reduced power of cruising speeds. 
To enter fully into the question would be to take up a very warm present- 
day discussion which has nothing to do with internal combustion engines. 
Therefore, it is preferred to make the comparison on the basis of coal burning 
boilers and reciprocating steam engines as opposed to the internal combustion 
heavy oil engines. After all, the comparison boils itself down to steam 
versus oil engines. 
The principal data of the Paul Jones are as follows: 
LLGGERS.S eC Ae OCS cen eae ee ea 250 ft. 
1B4SGidat SN Gc care Pa RS Ey Oe ee De Mit, (6) soo 
JOANNE (GoaVee TCT) We Be IE NR ony area a Re ro Talis 
Displacement (sea-going trim)................ 470 tons 
WocshiClent Ol MUCHeSS. 84 4.24 See bh a sie ORS O.41 
There are four Thornycroft water tube boilers designed for a working 
pressure of 300 pounds per square inch, each boiler capable of developing 
2,000 horse-power. 
There are two engines of the four-cylinder vertical triple expansion type 
each of which will develop about 4,000 horse-power. 
The usual auxiliaries are of modern approved types and are excellent 
im every respect. 
With this steam equipment the Paul Jones gave most satisfactory 
service on her official trials, and has continued to do so in regular service. 
The most serious criticism which may be made of this type is its inability 
in times of emergency to make prolonged runs at maximum speed. Granting 
an engineer’s force efficient enough to maintain the machinery in proper 
condition for such a severe test, the complement allowed is so limited that 
the use of the total fuel supply at full speed is practically impossible. As 
a matter of fact not one coal burning destroyer of this type, has, during the 
past seven or eight years, the period of their existence, ever made a pro- 
longed run at full power, consuming its total fuel supply. In cruising the 
economical speed of these vessels has been found to be at or below 10 knots, 
due to the economy of the engines at low speeds. Occasionally one of these 
vessels will make a prolonged run at a little over 20 knots, but even then 
they are running with only a fraction of their maximum power. 
With a complete knowledge of what high powered vessels of this type 
will do under practical conditions, it is interesting to try to discover what 
they would probably do if their entire steam plant were removed, and 
replaced by internal combustion oil engines. 
