FARM EXPERIENCE WITH THE TRACTOR. 3 
the average farm, they have not been in actual use under service 
conditions for a sufficient length of time to demonstrate their utility 
conclusively. 
STEAM AND GAS TRACTORS. 
The self-propelled steam thrashing engine was the prototype of the 
modern steam tractor, the latter differing from the former mainly in 
the size of the drivewheels and transmission gears. In other words, 
the steam tractor, generally speaking, was an outfit designed pri- 
marily for stationary use, but it was gradually adapted to the 
heavier work of hauling implements and to other work requiring 
power. A number of years were required for its development, but it 
finally proved its value on the large areas of prairie opened up for 
settlement in the West. 
At its best, however, it had several serious disadvantages. It 
burned bulky fuels, of which it could carry only a limited supply and 
which required considerable time and labor in conveyance. It con- 
sumed a large amount of water, which in a dry country was fre- 
quently a serious handicap. It was heavy and cumbersome and 
required a man of considerable ability to operate it properly. It 
ordinarily employed a crew of three to five men and of two to four 
horses. A delay of half an hour or more was often experienced in 
getting up steam pressure sufficient to commence work, and consid- 
erable fuel was consumed in keeping up steam during stops. In 
many cases the fire would be maintained all night in order to have 
the engine ready for work the next morning. 
These objectionable features were practically overcome by the gas 
tractor. It burned a fuel of less bulk and attained a higher thermal 
efficiency, so that it could easily carry sufficient fuel for a half day's 
run, and in many cases for much longer. One 2-horse load of fuel 
would keep the engine in operation for several days. It used com- 
paratively little water, and, if desired, a low-priced oil could be sub- 
stituted for water in the cooling system. It weighed less per unit 
of power than the steam tractor, was shorter, and could therefore 
turn in less space. While it demanded a thoroughly competent 
operator in order to secure the best results, he could easily attend 
to the entire operation of the engine and would frequently find time 
to operate the plows as well, although the crew usually consisted of 
two men and occasionally of three men and two horses. The motor 
could be started in a moment's time, and no fuel need be consumed 
when the outfit was idle. 
After the steam tractor had been used for plowing for several 
years, an insistent demand developed for a plowing outfit without 
the disadvantages of the steam tractor. The early gas tractors were 
built largely to meet this demand. The gas tractor has therefore 
