2 BULLETIN" 174, U. S. DEPARTMENT OF AGRICULTURE. 
exceptional, results from their outfits. At the same time, men who 
have not succeeded are not usually inclined or afforded an opportunity 
to make their experiences generally known. It is necessary to con- 
sider carefully the results obtained by all users, whether they have 
succeeded or failed, in order to obtain correct information as to the 
present status of the farm tractor. The data in this bulletin are based 
upon the experience of a large number of users in both classes. It is 
important for everyone interested that a reliable and impartial survey 
be made available. The relative efficiency of various makes of 
tractors is not considered in this bulletin. It is obvious, however, 
that this factor of the efficiency of some particular machine may be a 
most important one to the individual farmer. 
DESIGNATION OF TRACTORS, 
Owing to the numerous terms used to designate tractors in various 
sections, it may be well to state that in this bulletin the term "gas 
tractor" is used to designate those machines which derive their power 
from an internal-combustion engine burning a vaporized fuel (regard- 
less of the kind of oil burned), which are designed for pulling imple- 
ments and for doing stationary work. When the term "gasoline 
tractor" occurs it denotes an outfit of the kind just mentioned in 
which gasoline is regularly used for fuel. Similarly, the term " kero- 
sene tractor" is used to denote a "gas tractor" in which kerosene is 
the ordinary fuel. By a "steam tractor" is meant an outfit deriving 
its power from steam generated in a boiler, heated by means of a fire 
of coal, wood, straw, or similar fuel. 
The smaller machines, designed especially for cultivation, plowing, 
etc., commonly known as "autoplows" and "autocultivators," in 
which the tillage implement and power plant are combined in one 
unit, have not been considered in this bulletin, as these do not prop- 
erly come under the title of tractors. While there are numerous types 
of these small self-propelled plows and cultivators intended particu- 
larly for use on small farms, few of them have been in actual service 
long enough and in sufficient numbers to demonstrate their ability 
to perform the work for which they are intended. 
Nor should the data or remarks contained herein be considered as 
applying to the various types of small tractors designed to pull two 
or three plow bottoms and selling at a comparatively low figure, large 
numbers of which have been placed on the market during the past 
few months. These small, low-priced outfits represent the latest 
phase of the development of the farm tractor and may fairly be con- 
sidered as belonging to a different class than those under discussion 
in this bulletin. While they give promise of proving an economical 
source of power for a great deal of the field and stationary work on 
