12 BULLETIN 3, U. S. DEPAKTMENT OF AGKICULTUBE. 
greater than 8 inches, whereas for the walking, sulky, and gang 
plows, respectively, the percentage plowing at 8 inches de^p is 17, 12, 
and 5. Four horses are used by 58 per cent, fiY&kszaes by 25 per cent, 
and six horses by 10 per cent. Many find it necessary to use more 
than six horses where the same horses work all day or on very heavy 
plowing. In the Central West gang plowing is often done with four 
horses working half days alternately. This inquiry has not sepa- 
rated these from the general averages in the table, since it was not 
feasible to provide space for this practice in the blank on which the 
information was obtained. 
When the gang-plow data were brought together by widths with 
averaged depths and vice versa, it would seem that the users of the 
wider plows had heavier horses and also did not plow so deep. With 
increased power at a given width, the depth increased. In gen- 
eral, the depth decreased as the width increased, while the acreages 
per day and per horse increased, and conversely. The analysis in- 
dicated that each 1,000 pounds of horse is loaded with 29 square 
inches in a cross section of the furrow with four horses, 25 square 
inches with five horses, and 23 square inches with six horses, and that 
these teams plow 0.86, 0.79, and 0.68 acre per day per 1,000 pounds 
of horse, respectively. 
A comparison of the reported acreages per 1,000 pounds of horse 
for sulky and gang plows indicates that the gang plows are somewhat 
more efficient when working at the same widths and depths. The 
fact that a smaller proportion of farmers use 4-horse teams on gang 
plows than use 3-horse teams on sulky plows indicates that four 
horses are much overloaded by a gang plow. This conclusion is also 
borne out by the fact that plowing deep is not so general with gang 
plows, as well as by the general opinion of farmers in regions where 
gang plows are used. The operation of plowing is a severe tax on 
horses, but its magnitude and cost encourage the tendency to load 
them to the limit of their capacity. The greater acreages plowed by 
the gang type are due in part to the more level land, to freedom from 
obstructions in the soil, and to the greater speed required of horses 
in the sections where sulky and gang plows are used. They may also 
be accounted for by the mechanical construction of the sulky frame, 
which makes it possible to hold the plow to its rated or other desired 
width more uniformly than can be done with walking plows when the 
horses are overloaded. In plowing, anything over 25 square inches 
in cross section and 0.65 acre daily per 1,000 pounds of horse appears 
generally to be an overload. 
In Table IV data for gang plows have been compiled in a manner 
similar to that for Tables II and III. The daily duty for any desired 
unit of equipment and depth can be readily ascertained by inspec- 
tion of the fourth and fifth columns. 
