20 BULLETIN 111, U. S. DEPARTMENT OF AGRICULTURE. 
FUEL SUPPLY. 
The showing made by the kerosene tractors in comparison with 
those burning gasoline is of special interest in view of the compara- 
tively recent introduction and development of the kerosene tractor. 
A few years ago the supply of gasoline could not be increased 
rapidly enough with the distilling systems then in use to meet the 
requirements of the thousands of gasoline engines of all kinds being 
manufactured. As a consequence, the price of gasoline gradually 
increased. 
The engine manufacturers, therefore, fearing that the rise in the 
price of gasoline would hurt the sale of their product, devoted their 
efforts to developing an engine which would burn the heavier and 
cheaper oils. At the same time the oil refiners bent their efforts 
toward developing a process which would produce a larger quantity 
of the lighter fuels from the crude oils. Both have apparently 
accomplished their purpose. Engines are now on the market which 
apparently handle the heavier fuels with even better results in some 
respects than are obtained from the engines burning gasoline, while 
the oil refiners can now vary the quality of petroleum products 
at will. 
On account of a misunderstanding which seems to be quite general 
as to the present status of the fuel resources of this country, a short 
discussion of the subject will be of interest. 
There seems to be a rather prevalent opinion that the supply of 
fuel oil is rapidly nearing exhaustion, that the percentage of the 
lighter fuels, especially gasoline, which can be obtained from the 
crude oil, is growing less, and that the price of gasoline will there- 
fore soon increase to such an extent as to prohibit its use in farm 
engines. Statements to this effect are quite common and frequently 
appear in print. While appearances may have indicated such a con- 
dition a few years ago, recent developments in the petroleum indus- 
try prove that such statements have no foundation in fact at the 
present time. 
In the opinion of Dr. David T. Day, of the United States Geological 
Survey, the known oil supply of this country will in all probability 
be sufficient for the next 100 years. Dr. Day has been in charge of 
the petroleum investigations of the Geological Survey for a number 
of years and is qualified to speak with authority on this subject. As 
to the percentage of gasoline that can be obtained from the crude 
oils, Dr. Day, in a recent address before the Franklin Institute, spoke 
as follows: 
This consideration naturally suggests the vital question of an adequate gasoline 
supply. Even if we produce 25,000,000 barrels of gasoline in the next year this' 
would probably be too little for a year or two of further automobile progress. 
